RC India

Hello guys,
I am Karthick Ashwath. I want to build a solar aeroplane.I am now doing the background research for it. It is based on the Tern which is a flying wing designed by Holski77. Here is the link to it http://flitetest.com/articles/the-tern-60-flying-wing (http://flitetest.com/articles/the-tern-60-flying-wing) . I have finished the solar theoretical part of it (i have just completed the research, not built it) I want to find an electric motor which provides 700-900g of thrust at 3S and consumes LESS THAN 10A. Don,t mind about the kv or size, it is not important for the calculations. Could you please help me to find such a motor that costs less than or equal to Rs.2000, preferably from Indian sellers? If you want to calculate and find out the specs, you could try this link: http://ecalc.ch/motorcalc.php?ecalc&lang=en (http://ecalc.ch/motorcalc.php?ecalc&lang=en)

Thanks in advance,
Karthick Ashwath.

@karthick ashwath,

Notes made during some testing last year show that my DT750s delivered 700gms static thrust using an 11x5.5 EMP prop, drawing 9amps/110watts on a 3s. May meet your requirements. Available online from Indian hobby shops for Rs1300-1500.

I presume your wing area is about 4sqft, and all up weight including 3s 2200mah lipo (but excluding solar panels) will be 500-600gms. That should give you a payload capacity of 500-700gms (depending on whether lipo retained or not) for the solar panels.

Curious about the area and weight of solar panels to provide say 8-10amps at 12-15volts.
Regards

Hello,
Thank you KK Iyer for your recommendations. But could you please recommend a motor with more thrust? This kind of just makes it.Also, it would be great if you could find a 5010 360kv motor that fits this specifications. This motor may or may not fit the specifications, but it was what RCTESTFLIGHT used in his solar plane prototype video, where he mentions that it pulled 7.3A. Here are more details about my solar setup:
Seperate cell details:
Area 6x6"
Amperage:8A
Voltage:0.5
Total no. of cells:20
20 cells in series gives me 10v. I have refined my calculations , just to find that every thing was wrong.I will get back to you with the right details.

@karthick ashwath,
1. What's the weight of the solar panels?
2. Are you planning to use the solar cells to power the motor directly, or via lipo?
3. How did you arrive at your thrust requirement? You may like to look at this:
http://www.rcindia.org/electric-planes/iyer's-tech-talk-how-much-power/
Regards

Edit:
Many of the RCI members apparently think that the (static) thrust must equal or exceed the weight. This is true only for helicopters!

Oh, thank you very much Mr.Iyer then definitely this DT750 is the motor for me. AS you said,I had thought that the static thrust must exceed the weight. Now I get it. It need not.
Ijust figured that my selection of the airframe is very bad and that the area is not enough to fit 40 cells. So now I am looking for a new airframe whose wing area(preferably flat) is greater than or equal to 1440 square inches.And also your motor tips are very good!
Since I am looking for a new airframe, I would have to do the theoretical part again.
I planned to use 40 cells which would give me 160watts(minimum) and I don't know the weight but it is very light and fragile.
I am going to use solar as main power supply and 4400mah 3S lipo as backup(2 2200s in parallel)
Thanks,
Karthick.

@karthick ashwath,
Are you planning to use solar power as a primary source, or as a charger for the battery?
2x2200 3s will weigh close to 400gms!
Regards.

Edit
Are you tracking Solar Impulse?

I was planning one such plane months ago and here are my suggestions,

>You can place a small 1000mah Lipo( Tiger power from rcsportz is lighter enough than most other brands and provide a backup for most applications and power the plane directly from solar panel(primary source)
>though your calculation are correct you do not need 1:1 power ratio and hence you can fly a plane with well below power ratio.
>i believe you are looking at this solar panel: http://www.ebay.in/itm/Flexible-Solar-Cell-High-Efficiency-10-Pieces-/111769715570?hash=item1a05fe8372
If not please do. they have better efficiency i have seen so far, do refer me a better one if you have on in mind.
>motor selection will depend on the AUW and hence is not a question now.
> i choose a flying wing instead of conventional plane. there are lot of flying wing plans in outerzone.co.uk and here is my selection: Windfreak-RCM-11-78
 this one has lot of surface to place enough panels and balsa construction make it lighter enough and a flying wing is simple to build in balsa than a conventional plane and this is a simpler design with few good advantages.
>the extended nose on the front enables you to balance cg with minimum lead weight without a hefty battery.
>can be used in both tractor/pusher config with the same motor and prop config, no limitation of prop size by elevons however a pusher config needs a bit of modification.
>i prefer a tractor config and foldable prop for better efficiency, towline launch since the power should be just enough to fly the plane and not for a immediate takeoff.

these are my observation/study/research so far. i believe this is enough to get your project to jump start. let me know if you need any info.

@kk iyer
Yes, I like the Solar Impulse and I update myself about it on Facebook. Yes, I am planning to use 2 2200mah lipos only if they can be fit in the new airframe I am searching for. If not, I will settle for 1. Yes, I do plan to use solar as my primary power source.
Thank you sir,
Karthick Ashwath.

@v2eagle
I am actually looking at 6x6 inch square solar cell which actually perform better than these. It has a better area to wattage ratio. I am planning to use 40 of them.
Thanks,
Karthick Ashwath.

@karthick ashwath,
40 of 6x6 is going to need a wing of 10' span and 1' chord!
That's huge...

So, is it not possible to build an airframe like that that weighs <= 1400g using foam?
Or, we can half the no. of cells and reduce the area required and also reduce the size and power of the motor?
Eg.20 of 6x6 will give us 12 v at 7A and will have a power of 80W. So can we get a good motor that pulls <= 7A and have it power an airframe whose wing area is 720sq. inch? Can that motor power that airframe without stalling?
Thanks,
Karthick.

Difficult, but possible.
One important piece of data i don't have.
How much does each 6x6 cell weigh?
(I presume 12v, 300ma per cell, correct? And depreciated by the cosine of the angle of the sun away from vertical... ;D)

What about a land vehicle?
Can't remember where it is, but about 20 years ago, a visiting American had presented my son a kit for a solar vehicle, with a 1cm x 2cm cell, and wheels about 4cm dia.
Today's paper says solar autorickshaws being introduced...

That apart, do tell me the weight of each cell, so that we can proceed with planning your aerial project.
Regards.

I tend to think along conventional/sailplane lines because that is my area of interest.

New projects, however, need out of the box thinking.

Take a look at something called 'Nutball' on flitetest site.
Not exactly a good aerodynamic solution, but a 4' span will give you enough surface for 40 cells.
(If they are not too heavy  ;D)

May i ask you a question that i sometimes ask members of this forum:
What, Sir, is your objective?
Suitability of suggestions depends entirely on the answer...
Regards.

I dont have any data or calculations to share. But from what i read you are suggesting a plane similar to the impulse on a smaller scale that can fly all day and have enough juice stored in the batteries to fly all night and basically relative to pilot endurance on the ground flies forever. ???
first thing to consider is that it will cost a lot to build such a plane, secondly the building techniques have to be very refined and the design has to be very aerodynamic.
Why not try something similar to this: http://flitetest.com/articles/our-solarplane-dreamship-surprise

Even getting 2-3 hrs of flight with solar panels would be impressive. Long endurance planes and "UAV"s are easy to see in your head and on paper as a concept but making it work in the real world will require a lot of testing and refining with the materials and resources you have available.

All the best for this project :thumbsup:

@rcneil21
First of al, I would like to make a few things clear.
1.My plane is going to be capable of flying 11 hrs per day(as long as the sun shines), not all day long.
2.The purpose of the battery is to provide a backup to return/land safely, not to fly for 14 hrs.
3.My battery will probably be a 2200mah 3S lipo, which can sustain the motor at full throttle for 24minutes.
4.And till date , it has not seemed too costly to acquire 40 cells.

Thanks in advance,
Karthick Ashwath.

@kkiyer
Sir could you please stop calling me sir? I am just 13 years old.The weight  of each solar cell is about 6 grams. So 40 cells means about 240 grams. Also sir, could you please explain wing loading(your favourite subject)? I don't think I quite understand it. And 40 cells looks a bit overkill for this project.20 cells would be enough. As each cell gives about 0.6 volts at 8A, if we connect them all together in series, we would get 12v at 8A.  I am building this plane, I would gladly elaborate:
1.No limit to the extent to which I can fly
2. No limit for the amount of time I can fly(every fpv pilot's dream)(I have loved the feeling of infinity since I was very small. Eg. I have played with toy planes in my dream world imagining that they have infinite fuel, infinite...)
3.(this reason is one of the minor reasons)Giving the world a correct and complete tutorial on how to make a solar plane
4.This has been my dream for a very long time.

@kkiyer
Sir are you sure that the DT750 consume only 9A?Could you give me the prop using which it pulled only 9A and gave 700g of static thrust?It is absolutely unbelievable!Also, does it pull 9A at optimal conditions or is this at full throttle?
Thanks,
Karthick Ashwath.

Data from my notes of last year:

Motor DT750, prop EMP 11x5.5, battery 3s 2200mah turnigy & Haiyin from kinetic hobbies.

Amps Watts Thrust gms
 3.2     40      300
 4.5     56      500
 7.5     92      600
 9.0    110     700
11.0   132     800
13.6   161     900
14.4   168     950

Useful?

@karthick ashwath,

The purpose of putting the @ is to ensure that the recepient gets an email notification of a new post.
For that the recepient's handle has to be correctly stated.
@kkiyer gives me no notification.
Try @k k iyer
Anyway, since your project interests me, i check RCI every day. So don't worry about wrong tag!
Regards

@karthick ashwath,
13 eh?
Not much difference. (Only about 50 years ;D)
You are at the right age to dream of the future. Do continue.
At 13, I built my first model truck, with a reverse feature, that enabled me to get the Junior Science Talent Scholarship. At 16 I built my first wind tunnel, that helped me get the Senior Science Talent Scholarship.

But you have to be careful about your data.
You said each solar cell gives 8 amps at 0.6v!
Is this right? (see edit below)

And,
Remember my query about objectives?
1. Getting solar cells to power a motor adequately is one project
2. Building an airplane model that can fly reliably, is an altogether different project
3. Combining the two above is the third project...

Best wishes. Don't let a few obstacles stop you.
See this.
https://en.m.wikipedia.org/wiki/The_Spirit_of_Butts%27_Farm

Edit: 8amps could be correct from 6"x6".
The 3"x3" panels on the Solar Dreamship (flitetest) apparently give 2amps (@0.6v).

Sir, according to my calculations, using the formula P=VI, I found that:
Motor requirement 120W(9A+1A extra x 12V)
Solar cells required = 20(gives 12 v at 8A when in series)
120/8 = 15(total watts required/no. of amps produced)=no. of volts required
15-12=3
3/0.6=5
So if we have 25 cells in series we will get 15v at 8A(120W)
So if we use a simple DC-DC step down circuit, we can get around 115W with ease(approximate)
I chose this method of putting 25 cells in series and stepping it down as it is easier and lighter to add 5 cells instead of a greater number that would have been required.

According to RCTESTFLIGHT, who is building a solar airplane and is in his fifth attempt,
Power produced by solar cells is inversely proportional to temperature.
So, if we apply that here, we find out that when the plane is cruising, cool air will be rushing over it. The extra efficiency of cells will be balanced by the loss of efficiency due to the angle at which it is to wards the sun. So we can expect realllllly good results(I suppose so)

And, can anyone suggest a good airframe with at least 900 square inch wing area?And could I use a DT700 instead of a DT750? Many say that the DT750 vibrates a lot which may damage the solar cells. But the thing with the DT700 is that it gives lesser thrust at the same weight. So if anyone has any motor thrust test data for the DT700, please post it here. It will be very useful for me.Also, can anyone say who is the manufacturer of this motor? I do not know which manufacturer to select when I am using a thrust calculator.

Thanks in advance,
Karthick Ashwath.

All the calculations are good. One question is this your first RC plane build?
The manufacturer of DT700,DT750,DT900 and DT1000 is Hextronik a subsidiary of HobbyKing i think.

So with a 90" span and 10" chord and i am assuming a rectangle shaped wing and model weight of 1.5kg your looking at a wing loading of 26gm/sq.dm.
Which is a pretty good loading. If you get it to around 1kg AUW which is very hard for this size plane with the solar panels and battery it will be even better.
Also For stable flight characteristics you will have to use a polyhedral shape wing which will reduce the amount of wing area at optimal angle and also give less efficiency but you wont have to fight the plane and it will make your plane more easier to fly. There is a lot of planning to do Karthick, your very lucky to have Iyer sirs guidance something that rctestflight and another guy who attempted making a solar plane, mygeekshow didnt have.
So your success rate is definitely higher than either if you can execute everything well and Follow the guidance,advice,modifications and instructions of Iyer sir to a T :thumbsup:

Wow.
Undeserved praise! Made me blush at the thought of Gusty sir and other old hands laughing.  :giggle:
Remember that i'm only a self taught amateur, not a pro!

A few thought experiments to start with:

1. If 24 6x6 cells could be placed in a 2x12 grid on the wing, the minimum wing size is 1'x6'. But this will be possible only of the cells are flexible enough to go around the top of the airfoil.

2. If not, they will have to be placed on the rear 2/3rd or so of the chord in a 1x24 grid. This will need a wingspan of 12'! And chord of about 9". Aerodynamically good (with aspect ratio over 13), but not so easy to construct both strong enough and light.

So the first question is "are the cells flexible?"

No sir they are not flexible. But sir, I thought of building the solar panel array on a normal rectangular piece of foam and connect it to the motor, which I plan to leave out in the sun all day and find if the motor keeps running. Is it advisable to do such a thing?And I also plan to take periodic amp,volts and thrust values(record them/note them down). So, if this is successful, I think we could continue with this project.

Sir, I heard some people say that the DT750 sounds like a coffee grinder and they recommended to use a DT700. So what motor should I use? Or should we broaden our scope and look at DT 900 and 1000s?

And sir, don't you think it would be better if we use flying wings as our airframes?Also , it happens to be 25 cells, not 24.

Thanks in advance,
Karthick Ashwath.

 

@rcneil21
No sir, it is my second rc airplane build.(ironic)Thank you very much for your wishes!
Thanks in advance,
Karthick Ashwath.

 I have found that even a Kfm-2 based flying wing with 96" wing span is not enough. So we must look at huge planes or find a different motor that consumes mush lesser current. Hope that you could help me.
Thanks in advance,
Karthick Ashwath.

Karthick

I think you should have a look at the current multirotor motors with kv in the range of 300-400. They would use big props (15-17 inches) and consume low amps. But these motors cost some bucks and won't be in 1300-1500 Rs range.

If you can spend some bucks have a look at motors like T-Motors Anti Gravity 4006 380 kV. If you believe the manufacturers data, it produces 380 Watts of power and weighs mere 66 grams. These are the lightest motors I have come across till now. However they cost 150 USD for a pair.

Oh no, sir , but that is way out of my range. Sorry. I will see if I can somehow obtain those motors.
Thanks in advance,
Karthick Ashwath.

@karthick ashwath,
RIGHT!
Exactly what i've been considering.
Tell me, do you have the cells with you or yet to get?
Do you have ANY motor for testing? (Don't buy a motor yet. Wait. You can use a 12v car headlight bulb of 50/55w as load)
Do you have a wattmeter that can display amps and volts simultaneously?
I agree that the first test has to be with some or all cells mounted on a flat plate, to check output at different angles of sunlight.
And for the present, put 10+hours etc on the backburner.
Just now we need to establish how much power we can get for say half an hour around noon.
(Flying wing or conventional etc we'll discuss a bit later.
And what is the weight of each cell? 6gms?)
BTW, I'm free till 9. So we can exchange msgs back and forth.

Sir, though I do possess a motor for testing, it consumes 3000W, which is way too mush. I can build the constant current load setup which will pull 10A at all times, or as you said, I can simply use some car headlights. Yes sir, the weight of the cell is 6gms. I will ask my acquaintances if they have a watt meter which they can lend. I will somehow acquire one, or I will simply resort to multiplying amps and volts. But no sir, I have not bought the solar cells yet. This is just research. I will acquire them as soon as possible.

Thank you very much for your excitement,
Karthick Ashwath.

@k k iyer
Sir thank you very much for your excitement and interest. Thank you sir!

3000w?
4hp?
Probably not meant for model airplanes ;D

Sir I made a terrible mistake. Sorry. It has 366W at 3s and has 3000kv. Sorry sir.
Thanks,
Karthick Ashwath.

Regarding 24-25 cells.
I think with solar cells, when sunlight reduces, it is the current capacity that reduces, and the voltage remains the same. Pl check if this is correct.
So instead of 0.6x25=15v, 0.5+ x24=12v-13v should be ok.
I've not yet checked the internal resistance of solar cells, so i don't know how much the voltage will drop under load. With lipos it often goes below 11v at full throttle...

But sir, I am not sure of what happens at such times. I will try enquiring about it.

@karthick ashwath,
This project needs to be broken into 4 parts:
1. Capability of power source (solar)
2. Power required
3. Aerodynamic issues / payload capacity
4. Structural issues.

The last three are interconnected.

Let's tackle no 1 first.
The one thing we know is the per cell voltage (0.5-0.6v)
To emulate a 3s lipo, we need 24 cells.
To emulate a 2s lipo, we need 16 cells.

The questions before us therefore are:
1. How much current can they produce?
2. How much do they cost?
3. Should we get 16 or 24 or 25?
4. When will they be at hand?

You can answer 2 & 4.

Meanwhile i'll try to evaluate the amps and thrust with larger props at 2s voltage with some of my motors (DT700 or 750, not sure, DT850, CF2822 1200kv, 2836 1000kv etc)
May take me some time as my 2s lipos have jst connectors, and ESCs have XT60s. And i don't have jst's to make up jst to xt converters.

If you would like to tackle some more issues, i'll put them in my next post  ;D

Sir, that reply is very good. Anyway, I will try my best to answer all the questions.
Question No. 1
 Ans 8A at maximum(reptitive, sorry)

Question No. 2
Ans. They cost almost Rs.4500 for 30 cells but this is on ebay.com and since this includes shipping this is costly. I will speak with a dealer whom I know and ask about this to him.

Question No. 3
Ans. If we are using 2S at around 80W so we will need 20 cells(I have taken 80W instead of 78 and have also taken per cell wattage as 4W)

Question No. 4
Ans. Probably by the end of this month(maybe) but this will become true only if our research becomes conclusive and we settle on a single setup. My parents will allow it only if we have conclusive evidence(my mom has a physics background, she will check all my calculations) ;D

Thanks in advance,
Karthick Ashwath.

Ok sir, I am thinking of getting a single cell and examining its characteristics to find the amps , watts and the volts at different times of the day(i am going to place it there at different times, not leave it there as it will increase the temperature of the cell which will definitely reduce the no. of amps produced). This will prove to be priceless for future calculations.

Let it heat!
Not going to use an umbrella on the plane!

No sir, not that we are going to use an umbrella for my plane, its that while flying, the wind will cool the cells.

Sir, I just saw a Five piece solar cell pack being relisted in ebay.in. Shall I buy it for testing? According to it, it cost Rs.170 per cell.Not bad. I just came across it. Here is the link<link>http://www.ebay.in/itm/Educational-Solar-Cell-High-Efficiency-4-33W-5-pieces-/111798896253?</link>. Sir it is a very hot item so it may go out of stock in a couple of days. please inform me about the thrust test, if you have completed it. Could you tell me what soldering iron you use?I also want to know what setup you use for long range FPV.

I have a multistar 4010-375kv motor invade you need it.

JK

@karthick ashwath,
You may be confusing yourself by tackling too many different issues at the same time.
1. To check out solar cells, you have to get some. Whether it is worth it it is something only you and your budget can decide.
2. What soldering iron i'm using has no connection with this project.
3. FPV? What's that?

Have you even flown an RC plane yet?
Let your imagination fly, but don't let it ignore reality.
Get your feet firmly on the ground.

To make a solar airplane you need to know two things
1. How much power is available?
2. Is it enough to fly my plane?

If it was simple, others would have done it already, no?

Um sir, to be frank I have not but I have flown one in my simulator with a real Mode 1 remote. Yes sir, what soldering iron you use has no connection to the project , it is because I am thinking of buying one but don't know which one to get. Sir, FPV stands for First Person View(by placing a camera on the plane, transmitting the video and receiving it on the ground, mostly using 5.8 ghz due to its free use in India)

And your philosophy is good, which is what I often keep reminding myself about. Sir it is not simple, but it looks like a bit of the starting of the forum when you say:
Sir please confirm whether it would be correct to get those cells.

Sir I feel that it would make things a bit (just a bit, not a lot ;D) if we use an existing glider airframe as they are large and they are designed in such a way that they fly for a long time as it would be perfect for our project. Gliders can be used because we do not require a lot of speed(just 2.5-3 times the stall speed  ;D)

Sir could you please tell me a time when we can come online together so that we can discuss things a lot more efficiently? We could decide on some time form 6.00 to 8.00 pm(when I am allowed to do my research)

@karthick ashwath,
You answered my FPV question, without even realising that it was a rhetorical question!
Obviously you thought i dont know what FPV is...

You appear to have gained enough knowledge to not require any further assistance.

So goodbye and goodluck.

Sorry sir that was not what I intended. No sir, I cannot accept that I have gained enough knowledge on this topic. Maybe I had been rude, too overconfident, my bad, please don't take any offense. Sorry again. I am just a newbie.  :'( :'( :'( :'(
 :'( :o :'( ??? :'( :'( :'( :'(

Sorry again. Hope that this doesn't happen in the future. My bad,I accept.

Sir, I like this particular plane for our project. It is a Allegro Lite 2m balsa glider. Many people recommend this glider. Here is the link to its plans:http://www.charlesriverrc.org/articles/allegrolite2m/Allegro_E_Lite.pdf (http://www.charlesriverrc.org/articles/allegrolite2m/Allegro_E_Lite.pdf)

A DT700 running on 2s would be more than enough for this plane.ccording to the winf=g area of the plane, we can fit 13 cells (actually 14, but some area is curved, so 13) which will give us 7.8V at optimal conditions.

I have purchased the solar cells. It will arrive on October 28. But my exam ends only on Nov 5. So you could expect the test results by 7 Nov.(exam is yet to start)

But I have 0 experience with balsa so a foam glider with about 2M wingspan would be good.(I am unable to find one.)

Though I cannot find a good foam glider with 2M wingspan, I would like to know whether this glider would be enough>It is the photon, has 60" wingspan 5" root chord. I do not know the other details, which is why I am unable to calculate the wing area.

Link to video(by Experimental airlines): https://www.youtube.com/watch?v=ZfqGrzCKauw (https://www.youtube.com/watch?v=ZfqGrzCKauw)

Link to a preliminary pdf plan: https://docs.google.com/file/d/0ByhtTaHuhLwvb3luRDJhMjdkTEU/edit (https://docs.google.com/file/d/0ByhtTaHuhLwvb3luRDJhMjdkTEU/edit)

Or would using the FT Simple Soarer be a better idea? Link: http://flitetest.com/articles/ft-simple-soarer-build (http://flitetest.com/articles/ft-simple-soarer-build)

I have come to the conclusion that using the FT Simple Soarer would be better because:

• It has a part of the wing which is totally flat(perfect for solar cells)
• It is a tried and tested model and its tutorial is better

But, as of now, I am undecided over what scaling to use. :help:
 It has a wingspan of 44"
 Root chord 5.5"
 Flat chord(part of the wing which is flat ;D) 4"

If I use 150% scale, I will get:
 66" Wingspan
 6" flat chord(perfect for a 6x6" solar cell)
 Can place about 10 cells(part of the wing is curved)

Link to the plans:[link]http://www.stonekap.net/ftplans/FT-SS-plans.pdf[/link]

If we place 10 cells, we get 40W.(only at 6V)
So we must use a DC-DC voltage boost circuit and step it up to 8V. So we will have at least 6A.
The DT 700 consumes 4.5A at 2S while running a 11x4.7 prop. So there is enough room for loss due to angle at which it is facing the sun, power for the receiver and clouds.

Are there any mistakes in this calculation?Is the scaling up correct?Would it provide this 40W?Will the airframe be able bear it?

 :help: :help:

Can anyone help me to scale up the plans? I don't know how to do it. And could somebody please give me the prop test data for a DT700 on 2S? It would be wonderful.

Update: I have decided to use NCR18650B as they weigh only half as much as lipos but have the same mah rating. More info here: [link]https://www.youtube.com/watch?v=adfydRg8PYU[/link]

Can anybody tell me what kind of landing gear I must use?

But be aware . Only and only use genuine panasonic ncr18650b cells and remove their safety ckt  and make sure to leave extra leads for charging terminals . Just take care while working with them

I just burnt my rc tank(cardboard) due to mis handling those are no less dangerous than lipos .
Btw which solar panels you will be using i would recommend the vega robokit panels. . Quality stuff

But sir, vega robokit takes long time to ship. For more info on what solar cells I have used pls check the other pages of this thread sir .Thank you for your advice sir.

Please Dont call me sir i am just 17
and about vega . They are india based

Oh i forgot to see previous pages . Go for the flexible ones their effieciency is nice  and go . And regarding the airframe a flying wing could be a better option .

Your ideas and suggestions are good sir. But I have gone through these topics in my head, but I found that though flexible solar cells are less fragile, their watt to area ratio is not vey good though they claim thei efficiency to be high. And they are mush costlier and large.

The reason for me selecting motor gliders/electric sailplanes is that they are designed to be light, give a lot of thrust and have a large wingspan. As we can glide, we can use the time when the throttle is chopped to charge batteries.

At first I too thought of flying wings, but later switched to motor gliders.

We share the same way of thinking ;D.

Thanks,
Karthick Ashwath.

The DT700/750 was only suggested as an answer to your above query.
May not necessarily be the best solution to your project. So don't get fixated on it.

Let us look at the data we have:
1. 6x6" cells of 0.5-0.6v and 8amps max, or say 4watts
2. For a 2s lipo emulation we need 16 cells, say 64watts
3. 16 cells laid out in a line would need an 8' wingspan
4. Assuming that the flat portion of the chord would be about 2/3rds (since the cells are not flexible), about 9" chord would be needed.
5. That means an 8'x9" wing, or say 6sqft
6. Assuming that you could build a 6sqft wing down to a 6oz/sqft loading, it would weigh 36oz or 2.25lbs, or 1kg.
7. 64 watts would give a power loading of under 30watts/lb, or just about enough for level flight without any reserve for climbing.
8. The all up target weight of 36oz (for a 6oz/sqft loading) includes the payload.
9. The payload would be say 100gms for the cells, 80gms for a DT, 50gms for servos and esc, 80gms for a 2s 1000mah lipo. Say 300gms or 10oz.
10. That leaves some 26oz for a model of 6sqft wing area, or 4-5oz/sqft.
11. Not easy for a model of this size, but possible with some CF tubes and depron or balsa.

So while waiting for the cells, you could experiment with some depron to see how much a model of 8' span and 9"chord will weigh. Assume horizonal tail are of 25% to start with.
Then we can consider whether an Emax CF2822 turning a large prop on 2s is better...
(Thought you are not available till 2nd week of Nov...)
Regards.

Sir, that seems very reasonable. But sir please take a look at this(I may be wrong,please bear with me ;D)
Wingspan of FT simple soarer = 54"
Wingspan of 150% simple soarer = 81"

Flat chord = 5"
150% flat chord = 7.5"

Area available for solar cells = 81*7.5 = 607.5sq. inch  (let us take as 600 sq.inch)
No. of solar cells that can be fit = 600/36 = 16.6666666666 = 16

Exactly the no. of cells we need for a 2S! Yay!

Total weight of the airframe = 150% of 320 = 480gms

Weight of the solar cells = 6x16 = 96gms = 100gms

Weight of all the other electronics(thanks for calculating the weight of the electronics) =  250gms

Total weight of the aeroplane comes at about 850gms sir. Would 50% thrust be required or should we choose 35% thrust(according to your guide to motor selection sir ;D)

Yes sir, I do agree that the DT700/750 is the best motor which fits all the categories. sorry for getting fixated about that.

And sir, thank you for putting up such a good summary of all the data we have! ;D

Thank you for simplifying everything sir. Was eagerly waiting for your reply sir!

Sir, what do you think of using genuine Panasonic NCR18650B batteries instead of traditional lipos?

Sir, what type of spar configuration do you think we need sir?

You surely can use the panasonic cells but you there is a catch. According to what I know about ncr cells have a c rating of about 2/3 which when multiplied by the current which is 3.4 is something between 6.8 and 10.2, donxt you think you'd be pushing it to it's limits which may be harmful for the cells. I am not sure though.

@karthick ashwath,
No idea about the Panasonic battery.

When you double a linear dimension, the area increases by a factor of 4, and volume by a factor of 8.
So does the weight.
A 1.5 size airframe will weigh 1.5x1.5x1.5 times, or 3.375 times the original.
If the original is 320gms (without payload), the 1.5 times one will be 1080gms! (Without payload)
Please check if 320gms is all up weight, or only bare airframe.

I presume the solar cells cannot be cut to 1.5"x6".
So a 7.5" width can take only one cell.
And 81" span can take only 13 cells!

Yes sir I totally forgot about the doubling.
No sir, it is the weight of the bare airframe without any electronics. Accurate weight of airframe is 311 gms.

Yes sir i totally forgot about that factor. So we can get a maximum of only 52 W. Must start looking for a new airframe.

Maybe should we go back to square one and start a search for a different airframe(maybe we even have to start looking for a new motor)

Hope that someone,you,or me is able to find a good foam electric motorglider which fits all our requirements (at least most of it) 

We now have two choices:
Either to use an existing design or
Design one ourselves! This may or may not be possible, taking in account my experience with rc.

Hope that we could come to a conclusive decision.I would really appreciate any help.
 

@karthick ashwath,
Remember my saying that
1. Getting solar cells to power a motor adequately is one project
2. Building an airplane model that can fly reliably, is an altogether different project
3. Combining the two above is the third project...?

I'll add one more.
4. Learning to fly an RC model is an entirely different project in itself.

Do NOT combine these 4 in a single attempt!

I had also suggested that you look at the flitetest Nutball.
Please do so now.
It is not so great aerodynamically, but it can take 25 cells in less than 4' wingspan!

Questions:
1. What do you calculate as the minimum span required to accomodate 25cells? Or 16 cells?
2. What equipment do you already have?
3. Have you made a list of items you need and their cost? Please share the list.
4. Have you considered the cost of replacing items that can get damaged (eg, props, motor) or because they were the wrong choice (eg, motor, props, esc, batteries, charger)? Will your budget cover these?

Several times I've lent, on a returnable basis, stuff required by newbies, to help them avoid wasted expenditure. But i guess you can manage on your own  ;D.

Please do answer the above questions specifically, so that i can share the next steps i have in mind.

But if you have exams, turn off internet, and do not post on RCI till they are over.
Sms me when free.

1.Sir I go with 16 cells and I take the maximum wingspan for conventional airframes as 17*6 = 102", this is when the width of the aeroplane can only support one cell.

2. I already have:
1 366W motor
1 60A ESC
1 Orange Rx receiver
1 Orange transmitter
1 Skyzone 5.8ghz Tx Rx set
1 Camera
5 sets of XT60s
1 Orange transmitter
4 landing wheels
1 set of Circular polarized antennas for 5.8ghz
2 turnigy 2200mah 3s lipos
1 Turnigy Accucell 6 smart balance charger
1 10A SMPS (to power the charger)
2 APC style 7x5 prop
3 HXT 900 servos
1 multimeter
1 Soldering iron

3. No sir, I have not made up a list of the things I will need. Will make one soon.

4. No sir, I have not considered buying any extra props(I will buy 2) as I have a prop protection fan casing which I use to protect my props. As for the motor, I do not know what to do sir.
And yes sir, my budget will cover the cost

And sir, could you please say what you mean by

 

Sir, what do you think of using this glider:www.charlesriverrc.org/articles/aegea2m/markdrela_aegea2m.htm (http://www.charlesriverrc.org/articles/aegea2m/markdrela_aegea2m.htm)

I could build this glider by using depron instead of balsa except for the fuselage where I will use Dollartree foamboard. I could use Carbon fibre spars.

@karthick ashwath,

Good. You have nearly everything required. You'll need a hot glue gun, and props, pushrods, control horns, wire for undercarriage etc.

Well, you can build the Aegea if you like, though not a suitable choice in my opinion.

My recommendation is that you built a Nutball scaled up to say 44-45" dia. The reasons are:
1. Simplest configuration to accomodate 5x5 or 4x4 cells
2. Easiest construction. Can be built in a few hours.
3. Cheap
4. Easy to repair/replace
5. You can use your existing motor, esc, lipo
6. With this model you can teach yourself to fly, even if you don't have access to an instructor.
7. Fly it without the solar cells first. This will ensure you have a safe platform before you risk the cells.

Go ahead. Best of luck.

Sir but the op has a 366w motor with 60a esc. I don't think that would work.

Thank you sir. I will definitely get a new hotglue gun and, the benefits of the nutball seem almost endless. I will learn by using this plane. Safe to fly without an instructor? amazing!

You can expect this plane to be built by 7 Nov. By that time I will also have my solar cell test results ready.But sir, I came to know that it becomes very difficult to build large nutballs due to its requirement for light wing loading. I don't know what to select sir.

Sir what type of foam do you recommend for the nutball?

Thanks,
Karthick Ashwath.

Also there is one more thing to consider, the lift produced by the wings. I don't think it can fly with 64 watts on a 8v and 8A setup weighing around 700-900 grams. I don't think that's enough power for a giant nutball which has very less lift. It can't even increase it's altitude. You need a glider.
Experts correct me please

@rcrcnitesh,
@karthick ashwath,

Karthick has been looking at various alternatives.

Please suggest a suitable model that:
1. Has enough flat surface to fit 25 solar cells of 6"x6" each
2. Can fly on 100 watts
3. Can be built and flown by a newbie building his first model and with no prior flying experience
4. Will not cause too much heartbreak if it crashes!

Let me condense my reasons for recommending a scaled up Nutball:

It is the simplest and cheapest way to find out experimentally, the minimum power required to fly the smallest model capable of carrying 25 cells, especially for a newcomer. As opposed to an expensive, large, lightweight, multimotor model that could be built by an expert using carbon fibre

Why don't I try both the options and which one suits me the best? Sir, why don't we make a smaller Nutball, with lesser wing area, lesser weight and which requires lesser power? That would make things a lot easier. Nutballs get difficult only when you go crazy on the size. So let me try different diameters, experiment with them in my thoughts and by calculations, and find out what type of scale is best. I will keep my eyes wide open for even simpler airframes which are large enough.

Sir, I have a few calculations, according to which I need to build a Nutball with 60" diameter (approx) to fit 20 cells. I will love any tips and advice on the following:

1.How to build a large nutball with minimum weight with a Kfm-4 aerofoil and spar configuration(for 60" wingspan)
Any existing builds (if any) with a similar configuration can also be put up.
2. How to balance a brushless motor

Though I have looked at various pieces of information on how to balance a brushless motor, none of them are detailed. Any links/advice is very good.

I will post my calculations as soon as possible.

I have given up on finding any gliders with a flat surface as such a glider simply doesn't exist. Anyway, building gliders is not for the beginner.

Here are my calculations:
Required flat area not affected by control surface = 20x36 = 720 sq. inch.
Usable flat area = 8x12 = 96 sq. inch

Therefore, scaling up required = 720/96 = 7.5
If scaling up for area is 7.5, then scaling up for side is sq. root of 7.5 = 2.8(actually 2.73)

Scaled up length = 3(instead of 2.8)x12 = 36"
Scaled up width = 3x8 = 24"
Scaled up diameter = 3x19.3 = 57.9~58"

It is possible to fit 4 solar cells side by side along the breadth
It is possible to fit 6 solar cells length wise.(I will fit 5x4 )

Extra space is for battery,esc, etc.

I have referred to the plans by Flitetest which I have scaled up.

Please check and verify my calculations.

For balancing motors youtube/google/rcgroups is your friend.

My piece of advice would be to first build a avispad and learn flying on it with the electronics you have and learn flying on it once you are able to fly it properly then you build/buy the plane which you will use for the solar plane and fly it properly, then you can add the solar panels and test it. Till then you need not sit idle, you can do all the calculations and make your plans theorotically successful ;-)

25 cells in a 5x5 grid need 30"x30"
Diagonal is sqrt((30x30)+(30x30)), or sqrt 1800, or 42.426"
A 44" dia will leave 7" each left/right and fore/aft
Enough for bent up wingtips
Enough for elevator (more than enough)
Motor, ESC and battery go in the power pod / fuselage. Dont need any space on wing.

The whole point of suggesting this configuration is to:
1. Get a flyable model with your existing equipment, and initially without solar cells
2. Learn to fly
3. Find out experimentally the minimum throttle required for level flight
4. Use the same throttle position to check volts/amps/watts with wattmeter
5. Find a real answer to whether it can fly level on 100 watts or less. If not, we need an alternative, probably more high tech, using carbon fibre frames etc. if it flies at 100w or less, then the question is whether the solar cells can provide adequate power
6. If your tests of the solar cells show that 25 of them can give 8amps at say 12.5 volts, you can remove the 2200 lipo (about 180-200gms) and replace it with 25 cells (about 150gms)

I think it's time to move from theory to practical.
Tell me when you are ready.
Then we can discuss the materials required, the expected wing loading etc...
Regards.

Edit:
As well as your motor kv, potential prop sizes etc

Sir, I will start with a DT 700. Could you please tell me an Indian seller which sells this motor? I can't find one.
I will order the motor as soon as possible. But, please beware that around half of the parts that I have listed will be with me only from December. So I will have to wait till the winter holidays.

Sir, is a bent tip required? Or could I put ailerons there?Or shall I have a bent tip with ailerons?Please tell me what foam to use and where to get them.

I will be ready from 5 Nov. I will start building on the 6 Nov. and probably finish the airframe within the day(the whole day is a free day for me)

The all up weight is 700g. With the motor giving 900g of thrust on an APC 11x5.4 prop on 3S, it will be enough.

Warm regards.

I based my recommendations on what you said you have, so that you don't have to buy anything new.

Now i don't know what you have.
If you are yet to buy everything, please consider alternative designs.

Try not to open too many fronts at the same time. There is no end to possibilities. The point is to make a start. And move from theory to experiment.

Once you finalise your plans, contact me for any assistance you need.
Good luck.

Incidentally, it seems to me from theoretical considerations, that it may not be possible to build a functional solar powered aircraft model without recourse to a carbon fibre based structure of fairly large span.

A Nutball (which provides the maximum flat surface area for a given span) seems the cheapest, smallest and easiest way of finding out whether a model is able to fly on the power produced by the cells it is able to carry. Or whether a battery would be essential, and the solarcells would only be able to supplement it to extend the duration.

Meanwhile Karthick's experiments should reveal the output of solar cells under real conditions...

Sir I have already bought the parts it is just that it is waiting in my relatives' home in singapore. They are coming to India on Dec when they will bring it with them
 I did this to evade a hiccup from customs.

@ karthick ashwath,
See this.
http://webosolar.com/blog/wp-content/uploads/2013/03/I-V-Curve.png
Max power may be only ~70% of the rating.
Earlier estimates may need significant upward revision!
Practical tests with a few cells essential before proceeding.

OK sir, as mentioned earlier I will put up the test results only on Nov 6. The solar cells are yet to arrive. Anyway, we had planned the model with lots of surplus.

and I found a grave mistake in the specifications. It says that it can produce 4.2~4.3 w at 0.6V. so maximum current produced can only be 7A NOT 8A!

Anyway the motor produces enough thrust on 3S. Lots of extra power. No need to worry.

And sir, when I add the solar cells, I will have both the solar cells and the lipo for safety reasons. And when the solar cells produce more than that is required, it can be used to charge the lipo.

@rcrcnitesh
@ K K Iyer

I would like to make a few things clear. I have already tried all those and gave up. I simply couldn't find a guide to balancing brushless motors that is as good as K K Iyer sir's motor selection guide. Which means that I couldn't understand either. Sorry, but I am just a newbie. ;D

Sir please answer the following questions:
1. Where to get the DT700 motor in India online? I can't find any seller that sells these motors.
2. What type of foam do I use?
3. What configuration of landing gear do I use?
4. What spar configuration should I use?
5. Shall I take a watt, volt and amp reading every 20 minutes for 8hours for the solar cells?

As soon as you answer these questions (sorry, I don't know what to do without the answers for those questions) ;D, I will execute the following plan:


1. Make a test setup for each of the five solar cells
2. Evaluate all the results
3. Post all the results in the form of a graph
4. Build the airframe for a Nutball with 44" diameter
5. Test the motor as soon as it arrives and collect as many details about it as possible
6. Mount all the electronics on the Nutball
7. Acquire 20 solar cells(if nothing breaks)
8. Get a few hours of RC flying under my hood
9. Keep flying till I stop crashing
10. Mount FPV on the nutball

At the same time, I will be doing the following :
1. Mount all the solar cells in series on a piece of foamboard
2. Test the cells as a whole
3. Make it run the DT 700 reliably for quite a long while
4. Test the solar cells running a DT 700 at 80% throttle for 8 hours straight

Final step in making the solar plane:
Mount the panels on the plane and fly it! :thumbsup:

Future modifications:
1. Build a blunt nose flying wing whose blunt nose is a square of side 30" using EPO foam
2. Attach the solar cells to it
3. Complete the solar plane project Ver. 2.0! ;)

I will post more info on this Ver. 2 as soon as possible.

Again, I tell you that the test results for solar cells will be available only on 7 Nov.

Warm regards.

 

hey,
the nutball is a high alpha kind of aircraft which does not fly properly straight. i.e broken stalls ( The tail and nose are in not a straight line while flying!)
So when you are coming toward you, the plane will obviously face you with its nose up. Obviously you'll face away from the sun at all times. so, a moment will come sometime when the solar cells lose sunlight just because the plane is coming towards the sun!
Either you consider attaching a lipo or choose another plane(ft delta would do)

Here is a DT 750 not a 700
http://www.vibranthobbies.com/planes-parts/electric-motors/hextronik-dt750-brushless-outrunner-750kv.html

@prabal276
Thank you, but I don't know of any other aircraft that is as simple as this. Maybe I will make a small one as a trainer and then make that blunt nose flying wing. But I don't know anything for sure, so I will confirm this in a future post.
Thank you very much for finding the motor prabal!

Iyer sir pl. comment on reply #84
Wont the plane lose control for some time even if the plane loses sunlight for a sec.

I figure that what you say is right. But it won't lose control as it has a 2200 mah 3S 20C lipo from Turnigy. I planned on putting a lipo in there for safety. ;D

allright. Then its okay.

Re reply #84,
I said many times that the Nutball is not a great choice aerodynamically.
but it is the smallest airframe that can accomodate 25 cells of 6x6".

If you look at the link in reply 81, you'll see that the max power is well below max voltage times max amps. If you consider that most of the time during flight the sunlight won't be perpendicular, and that the brightness may also vary, perhaps we should not expect more than 50% of the Vmax x Amax!

So the power would probably be quite inadequate for flight on solar power alone.

However, the first objective of this project has to be to simply establish the power available from the cells under practical conditions, and compare it with the actual power requirements. And whether the solar cells will be able to charge the lipo when it is in use.

Meanwhile you could make an estimate of the weight of
the airframe+motor+prop+ESC+rx+lipo+Servos/pushrods+undercarriage and wheels,
assuming 5mm or 8mm depron as the material,
and 2 spars of carbon fibre tubes, say 3mm OD x 30" each.

Sundaram or sandy sir is selling dt700 motors if you are interested , contact him or refer to the second last page of his giant sale thread

To get you started,
My 38x25=950sqin 5mm depron sheet weighs 204gms...

Oh thank you very much sir. Do you still feel that we ought to go ahead with the nutball?
And sir, the weight of the airframe + electronics = 384 + 350 = 744gms ~ 750gms
The AUW when dollartree foam is used is 720gms.

Or shall I start drawing diagrams of my custom built blunt nose flying wing for the solar part of the project? And shall I have my first plane as the flitetest nutball? I have decided to buy a DT750 from Vibrant hobbies as soon as possible.

Do not forget heat shrinks and bullet connectors.
go ahead. Vibrant is a very good shop.

.

I am yet to purchase any heatshrink or bullet connectors. The solar cells have just arrived. Only one cell is broken. I have filed a guarantee claim on ebay. If anyone of you wants to get those cells, then hurry! Only one solar cell set is left! I will post the test details. I had promised a video of the unboxing, but the video is not good at all which is why I dropped the idea.

Could anyone please tell me where to get epo and depron online from Indian sellers?Not a single shop in this city(as far as I know) sells such kinds of foam. This is very important and would be highly useful for me. 

I think I mistyped that one in Reply #83. This sentence is supposed to mean that I couldn't understand the brushless motor balancing video, not the motor selection guide.
As far as I have understood, it is simply trial and error and trying the best to find the light side by using some tape. Then we must take the opposite side of the motor as the light side and subtract a little bit from it by using a Dremel/motor tool.

Am I right?

@v2eagle
I have done a little bit of research and I found that:
1. The Solar Impulse uses Maxeon cells (v2eagle recommended it to me in reply#6)
2. We are planning to use 6x6 solar cells
3. The maxeon is stronger and more durable.
4. though the Maxeon cells are said to have the best efficiency, it has a worse efficiency than these cells

All these are based on the data posted on the internet, not actual data collected by me experimentally.

And please don't even imagine buying those cells on ebay. They are costlier than their actual price. Here is the right place to buy them: RC Hyderabad

Has anyone bought from this store earlier? Has there been any problems?

My claim on ebay has been resolved. I will continue with the aforementioned plan only after testing the solar cells.

Can we please start looking for airframes again? I will buy the DT750 only after completion of testing.

And whoever you are, v2eagle, your selection is very good. sorry, but I checked that plane out just now. But the wing is not flat, which means I can't put my cells there.

I don't know the pros and cons of maxeon cells. The comparison between traditional cells and maxeon cells is in RC Hyderabad.

Note: I am not posting the link because for some reason or the other whenever I put the link and preview it , I get some other website. When I click it, it says that the website does not exist. It displays this: sp4mm3r.com. Why is this happening?

My exams have ended! I will start testing the solar cells soon.

which class are you in??

I am 12 years old and I am in class 8. This hobby is a way of keeping my thinking power concentrated on one thing.

i am in 9th.
i am going through FA3. last on monday!
after that will repair my avispad.
I entered the hobby when i was in 7th.

You guys are lucky that your parents supported your expensive hobby.

Well, that is true, but I chose the best bang for the busk parts. I only chose something else when there was no other way.

my father is happy to expend when i am upto something educational.
He knows my love with aviation and we are planning the best way for me to become an commercial or a iaf pilot 5 years later.
And BTW for my 1st plane, i saved the money my self.

Thats a great great dad . And it means you get pocket money.
Lucky one

Thats a great great dad . And it means you get pocket money.
Lucky one

Thats a great great dad . And it means you get pocket money.
Lucky one

Thats a great great dad . And it means you get pocket money.
Lucky one

Allright.
lets get back to kartick 's topic.
why post 4 times?

My wap connection . Admin help

The solar cells are working fine. Don't expect the test results any time soon. It is a bit cloudy here, so we have to wait till the clouds clear.

Hello guys,
It is still cloudy and rainy in Madurai, which means that I did not have a chance to test the solar cells. I will not be purchasing the motor because I have not come to a firm decision on which airframe to use. I will properly test the solar cells soon. I have also found this nice setup made just to test solar cells. It is feasible and easy for me as I need not buy anything more. I have a background in electronics(one of my hobbies) and I am familiar with the Arduino which is used in this setup. You can check it out here:http://www.engineersgarage.com/contribution/solar-panel-parameters-monitoring-using-arduino (http://www.engineersgarage.com/contribution/solar-panel-parameters-monitoring-using-arduino). I will be modifying this setup to include a fan and an SD card shield to record data every 20 minutes.

 I am yet to purchase:
20 cells(for 3S) / 11 cells(for2S)
Heat shrinks
Bullet connectors
Hot glue gun

There are some important and essential components which are waiting for me in Singapore. I will be in posession of them in the 3rd week of December.

My future plan:
1. Test the solar cells
2. Get loads of practice on the Nutball

To continue any further in this project, we will have to decide on the airframe. I don't know whether to continue with a large Nutball or to design a Kfm-4 based flying made especially for this project.

For 2S:
Diameter of the Nutball will be : 34"
Wingspan of the flying wing will be: 50"

I have planned to use a DT750 for both the setups.

But all this is not for sure as we do not know the true performance of the solar cells. Please give me some answers. I am confused  ???.Also, please tell me whether to use these 6x6 cells or maxeon cells (refer reply #98 )

Regards,
Karthick Ashwath.

Can you build this:
http://www.rcgroups.com/forums/showthread.php?t=2055551
It is damn slow and has a wing with no curved surfaces on top.
You can see the images.
It uses the same motor as yours.
 
wing- 60"x20"
I think i would suit your needs.

https://www.youtube.com/watch?v=mGLj43y-VUM

just read the build thread and clear all doubts before going on to build/Experiment!

Yes It is a good idea. I will make one (it is very simple) but I don't know where to get DollarTree foam board(that type). I can only get Elmer's acid free foam board which is a lot heavier but much stronger. It is not much of a problem as the DT750 has lots of extra thrust and a bit of strength is not bad. But I don't know whether I will be able to fit 25 cells. I can fit only 20 cells in a 60" by 12" rectangle. Where do I fit the other 5 cells? I also don't know what prop to use. The build process is perfect for a beginner.If we increase the fuselage width to 6" from 5", we can fit the other 5 cells. Thanks.
Regards,
Karthick Ashwath.

you can use depron.
I used Depron for my old fogey.
Just increase the wing length from 60 to 66.
I figure out that u have cells of 6"x6".
so 180 sq. inch of space is reqd. further.
so, increasing wing length to 76inch shoul do.

OR you may scale up the plans

yup, you can increase the fuse length if you want but for that, compensate by adding few inches to the wing length.
Prop can be decided later on according to A.U.W.
This plane would be excellent!

If I increase the wingspan to 72" and the fuse width to 6" I will be able to fit 25 cells if not more.The other option is to leave the measurements exactly as they are but ise 6x6 cells in the 12" part pf the wing and cover the 5" and 3" parts with 3x6 solar cells.

What do you mean by:
" I will be able to fit 25 cells if not more."

I will post clarifications in a second.

I have gone for a change of plans. I am not going to change any measurements to accommodate more cells. Instead, I will be putting 3x6 solar cells in the 3" and 5" parts of the wing and 6x6 cells in the 12" part of the wing. This means that I will be able to fit

12/6*60/6 = 2* 10 = 20 6x6 solar cells
3" part of the wing one set of 3x6 solar cells (10 cells)
5" part of the wing one more set of 3x6 solar cells (10 more cells)

So in total we will be able to fit 20 6x6 solar cells and 20 3x6 solar cells.

So at any given time, we will be producing :
3.5W per 6x6 cell(actually 4.3 W, but it will not produce this power on less sunny days)

1 W per 3x6 cell(actually 1.8)

So at any given time, we will be producing at least 20*1 + 3.5*20 = 20*4.5 = 90W

So there will be enough and more power to power the motor at full throttle and also charge the battery.(power of the motor on 10V on a 10*5 APC prop is 86W)

excellent going.
So whats the next step?

read the posts;
may help- http://www.rcuniverse.com/forum/e-flight-power-sources-126/10594707-can-i-charge-use-lipo-battery-same-time-urgent.html
i have compleated a 360 degreee in my no. of posts ;D ;D ;D ;D

If we supply 9.8V it puts out over 600gms of thrust on a 10*5 prop, it pulls 9A at 87W. Which is a bit more than 50% 1100gms(approximate) (minimum for an intermediate, not trainer plane is 550gms) Since it gives a bit over 617 gms, it is not a problem at all. Lots of extra thrust to expand. My source for all these details is this site http://www.flybrushless.com/motor/view/600 (http://www.flybrushless.com/motor/view/600)

I use this site as the DT750 is a copy of the DAT750 and it has similar specifications.

Congrats on completing 360 posts! As we won't be charging while discharging, we will not face this problem. When our solar cells produce more than that consumed by the motor, only then will we activate the charging part of the circuit. I am going to place an Arduino to control all these activities. oNly when our solar cells produce very low power will we use the battery.

its a good idea.
But first learn to fly on a sim before taking on a rc plane.
but you will be able to handle the old fogey ;)
So what is the next step that you are planning to do?
Building the air frame?

I already have a simulator and have atleast 50 hours of practice in a simulator on different planes, racers and trainers alike. And I exactly understand what you mean by

No, building the airframe is not the next step. I will have to contact a solar cell factory regarding the 3x6 solar cells which I have to test. Maybe get about 5 pieces.

I will build this airframe after testing. I must acquire quite a long piece of foamboard(I seem to know a source in my city) If you know any online foam sellers, please do tell me.

And, we have decided to use 5mm depron, haven't we? Or do I continue with foam board?

I may build the airframe during the winter holidays in december. Hope that your FA3 exam is over. Have you started to repair your avispad? I also have to wait for the other parts to arrive and I also have to order the motor, heatshrinks and bullet connector(first timer)

Is it necessary to use spars?

Foam sellers are mostlty not online. U have to search the city thourougly.
go on trade india, yellowpages kind of websites and see if there are any foamboard sellers.
Also ask the members of RCI from madurai (there are many) that where do they get depron from.
Click the members button which is in the header just below the RCI  logo.
Excellent planning friend.
Use depron. Its light and easier to use.
Spars have a great importance.  They prevent  :

1) the tail shakes on a fuselage
2)maintain wing rigidity on a plane and dont allow the wing to fold.
(My ft flyer wing folded once. One side of my ft old fogey wing folded once. All because i did not put an extra not-on-plans spar.)
My avispad is fine and repaired. Just waiting for some parts to arrive. I will maiden tomm.
Regards

I checked out everything you said. But there are very few plane lovers in madurai who have never posted even a single post. The few are interested only in selling. I have not seen instances of them clearing doubts before. I found an online supplier of depron foam. Check this out: http://www.kwalityproducts.in/107_Depron-Foam-Big-Size-6-MM.html (http://www.kwalityproducts.in/107_Depron-Foam-Big-Size-6-MM.html) If we purchase 2 of these, then it will be ebough. I somehow found an online seller of depron

I had not noticed that the wingtips are curved. So I will have to post a detailed arrangement diagram soon.

the wingtip is not curved friend!
They are just given an polyhedral

but the depron is toooo expensive!!!
We get one 40" by 30" sheet of 5mmm for 400 rs. here in delhi.

Do you know somebody in Mumbai? I know a close relative who often travels to mumbai for business reasons. Maybe he can get it for me. If you give me the address, my relative can get it.

Shriram Stationary Mart,
Shop 16, Radha Krishna Niwas,
Vachnalaya Marg, Dadar (W)
Mumbai - 400028
Ph. no - 022 24305982

call and try here
Regards

@k k iyer

Please do take a look at this:

Here, an EMP 11x5.5 prop is being used.

If we use the motor at the throttle level at which it consumes 7.5A and provides 600 gms of thrust, it would be very good. It would be enough if we fill just the rectangular part of the wing with cells. Maybe some more cells could be put just to make sure that we generate enough power.

Hello KK Iyer sir, been a long time since we saw activity form your side sir. Could you please provide the percentage of throttle at which it generates 600 gms of thrust and pulls 7.5A on 3S?

Prabal, hope your Avispad re maiden went well. I also hope that no major crashes took place. I look towards getting the depron from mumbai.

I will contact the solar cell seller I know and talk about acquiring those cells. It is still really cold, rainy and cloudy here, so I will test the solar cells a bit later. We can't be sure of anything till I complete the testing.

It went well! No major crashes or anything.
sanjay sir just recommended me some mods.

Seems good! Same here with my solar project! Would be enough if I fit solar cells just on the rectangular part of the wing.
I will put some cells on the dihedral part of the wing too just to make sure I generate enough power.

ok!
Seems like you are going for the old fogey.

Yes. Like it very much. It is slow , which makes it easy to handle for a first timer like me.

@karthick ashwath,
Earlier data was from my own test, but i didn't make a note of the throttle position.

Here is some more data (from 'Mortimer' on RCGroups) for DT700&750

Sir, that was very useful.I have used the data and selected to use a DT750 running an APC 12x3.8 at 60% throttle so that I could be sure that it gives about 600gms of thrust.

Can anybody tell me the pros and cons of using depron when compared to foam board?

Foam is heavier. Depron is lighter
Foam is harder to obtain in thin sheets.(a hot wire must be used. which, if you build costs approx. 1000) depron is available.
Foam crack is stressed. Depron gets cracks on it's surface and if paper/tape covering is there; it just weakens at that stressed point.
depron is easier to make complex structures with.Carving foam is hard.
Foam is better if you use it to make airfoiled wings out of with a hot wire cutter.

OK so we are now going to use Depron. That is for sure. Can anyone refer to some good tutorials or information about lamination? It is essential as we need to cover our solar cells to protect them. Can anyone help me in this topic?

Can anyone please recommend a good soldering iron for me? Something that would be of high quality and last a long time? I already have one, but it is not powerful enough.

Could you also recommend a wattmeter for testing my solar cells?

is that depron supplier in mumbai responding??

I have not tried calling this shop. I will get back whenever I do so. I will definitely do so.

Hello,
Been a long time since anyone saw any activity here. Sorry but I have been a bit busy at QC work at school.

There is a small change in plans. Instead of using the arduino, taking the risk of frying it, experimenting with saving data in an SD card, I have decided to take readings/measurements every 30 minutes for 10 hours
So 20 readings.

I am also having second thoughts about our power pod.I feel that either the speed or the thrust must be increased.But thrust is essential for takeoff, so better to have more thrust and use an APC 13x4 prop with our DT 750 motor.

But the recommended prop for this motor is 11x3.8.

Which prop family is best? APC or Master Airscrew or Normal props?

What should I do?Should I stay with this power pod?Should I use a different one?

Also can someone please recommend a good:
Wattmeter
Soldering iron
Hotglue gun

Thanks and regards.

Do you really need a recommendation for even a soldering iron?
I wonder why you ask. Asking is an easy way out. Why not find out for yourself?
Can't build an entire project on hearsay.
Put in some effort please.
Still have not heard how much power the solar cells put out.
We (at least I) await the results of your experiments.
Regards from a well wisher.

Sorry but seems like I will just find out for myself. By the end of december, I will have all my equipment and solar cells test results as I have a long holiday. Sorry, but I have tried my best. I have enquired in electronic shops already, but the best soldering iron they have to offer is a 25W soldron soldering iron. Don't know whether 25W will be enough.

I have already bought a hotglue gun but it didn't work.This is why I am asking a recommendation. (i bought a Crown brand glue gun)

As for the watt meter, I think I will buy it locally instead of going online.

Will put in more effort from now.

Thanks for the wishes.Happy to hear that someone is waiting on me for such things.

get simple SIRON or OSWAL brand iron and a few smd tips for future . costs <150  rs nice to work with. for hot glue gun go for rcbazaar or Indian hobby shop eBay ones preferably a 40 Watt .

check main lead  for your crown .

Solder, flux, iron, hot gun, multimeter etc available at this site which seems quite professional and has reasonable prices. A 25w iron should be enough for your needs.
http://store.vervetechnologies.in/tools
Regards.

Thank you for your recommendations. Any idea on whether to use a different power pod configuration or not? 
The problem with my Crown is that it does become hot, really hot, but no glue comes out of it.

@prabal276
@K K Iyer
Sorry for taking so long. Since you say that 25W is enough, I guess I will use my 25W soldron.

Prabal, I have contacted the shop and they say that one sheet of 5mm depron which is 24" by 39" costs 150Rs. sounds really cheap to me. 4 of these should be enough for my build.They also have mountboard and foam board with tmem.

I have watched some videos on how to tab and solder solar cells and they look pretty easy to me. I will get a tabbing kit soon and I will solder the 4 cells together.

You could expect the test results by next month.

My dream is to create a solar flight which will fly for 24 hours. Now when I was thinking about how to fly throughout the night, I got this idea:
The solar plane will charge the batteries and gain as much altitude as it can during the day. at night, the throttle will be decreased to 30% so that it will consume just 3A. By alternating between gliding and flying, we can get through the night i.e. by cutting the throttle and gliding for 30 minutes then going back to 30% throttle to regain altitude and then doing this over and over again. If this works, we will be able to fly with a total battery capacity of just 17ah (5 NCR18650B batteries) (700g)This is the battery pack with the highest energy density as far as I know.

Maybe the plane won't be able to take off due to the extra weight. If it is so , we will have to do something to solve this problem.

These are just plans for the future.This will take some time to become true.

@K K Iyer
@prabal276

I have found a huge mistake in the calculations!

According to K K Iyer sir's motor selection guide, our plane will not fly! Here's why:

Given:
Weight of plane (AUW) = 1200gms = 42.3oz

Area of plane = (30x20)+(2x5x20)+(pi x 10x10) = 600 + 200 + 315 = 1115 sq. inch (rounded of the circle's area)
= 7.74 sq. ft.

The values correspond to the :
1.Main rectangle at the centre
2.2 Edge rectangles
3.2 Edge semicircles (1 circle)

As the diameter of the circle is 20" , the radius must be 10". There fore the breadth of the edge rectangle is 15-10 = 5"

So we have found the area. Let's calculate the wing loading.

Wing loading = Wing area / weight = 42.23/7.74 = 5.45 oz/sq.ft.

So the stall speed is:
4-5 times the square root of the wing loading = 5 x 2.33 = 11.6 mph = 19 kmph

So the cruise speed has to be :
2.5 - 3 times the stall speed = 3 x 11.6 = 35 mph
35 mph = 56 kmph

So we now know the minimum speed. It is 56 kmph.

Using data by Mortimer from RCGroups, we know that the DT750 motor spins 4080 times per minute at 50% throttle with an APC 12x3.8 prop as load. Therefore, the maximum speed produced by the DT750 at 50% throttle is:
3.8 x 2.54 x 4080 x 60 / 100000 =  23 kmph.
Pitch x 2.54(to convert to centimetres) x RPM @ 50% throttle x 60(to convert minutes to hours) / 100000 (to convert to kilometres)

At 100% throttle , the RPM is 6180, so the speed is 35kmph.

We are going to run the motor at 50% throttle in the solar plane as it fits under the current produced by the solar cells.

19 < 23 < 56
Stall speed < Actual speed < Cruise speed

Conclusion: The plane doesn't fly.

Are these calculations right? Will the plane fly? If my calculations are right , how did the plane fly when it was built by balsa or carbon on RCGroups? ???

The details I posted in the previous post are wrong as I didn't keep in mind a variable ;D. Now in the corrected one, I have found that the solar plane can't fly for more than 13 hrs continously.

I have attached the plan of the wing of the old fogey.

Please do correct me if I am wrong.







 

@karthick ashwath,
Good that you have got into critical thinking instead of fanciful thinking.
Remember that there are several different issues:
1. Is the selected model flyable? Thousands of choices.
2. Will you be able fly itwithout prior experience? Choice narrows to a dozen or less.
3. Does it have enough flat area to accomodate the number of solar cells required to produce the reqd voltage and current? Choice reduced to 1, for smallest airplane with reqd area (unless you are prepared to build a Solar Impulse type with huge wings)
4. Don't get fixated on DT700/750. Look at alternatives like emax cf2822.

The first thing you need to do is to find out how much area of solar cells gives how many volts and amps.
You can do this before your other stuff arrives from Singapore in Dec!
Eagerly await results.
Regards

Thank you sir.
Are my calculations right? Will the plane fly? If not, then how did it work earlier?

 I am looking at a few kits to solder the solar cells together. Will order one soon.Maybe I could try soldering it next sunday.

I feel that the DT750 is a very good motor. I have checked that motor, but its maximum thrust is just 22oz whereas the weight of our model 43oz. So it is not sufficient. Maybe I will also try looking at different motors. Hope to release the test results as soon as possible.

Feeing frustrated.Can't find a good motor. But this keeps puzzling me : the speed of the plane seems to be lesser than 40kmph but it still flew for balsa and carbon.
Please help me with the motor.

@karthick ashwath,
This thread already has 159 posts without a single step of progress.
And lots of discussion unrelated to the objective.

The first step for a solar flight is what size of cell produces how many volts and amps in actual tests.

Till then, in my opinion, discussion is just social talk!

@prabal276

I have some good news and some bad news.Let me start with the good one, move one to the neutral one, then the bad one.
Good news:
No need to buy depron in Mumbai! I found a seller of depron. I am not sure whether it is depron or some other foam, so I will post some pictures of it when I visit that shop on saturday. Thanks to your advice, I found a seller here!
Please confirm whether it is depron or not after my next post.

Neutral news:
Our school is a part of the Microsoft create to inspire programme. One of its topics is environment. My QC Project on Global Warming has already been nominated. My solar plane has also been nominated. You can learn more about the programme here: http://www.microsoft.com/en-in/mobile/about-us/people-and-planet-page/create-to-inspire/program/ (http://www.microsoft.com/en-in/mobile/about-us/people-and-planet-page/create-to-inspire/program/)

Bad news:
I just visited the solar shop which I mentioned before to get the cells soldered together.(I took this step only because I was not able to find tabbing wire of a bit short length on ebay. The only one I found had a 200ft roll of it, which is way more than what I need. ) The person in the shop told me that they don't solder cells to make panels or anything, they just sell solar products. Even though it ended in vain, I was able to find people who make solar cells and people who make solar panels.

Seems like I should just use some single core wire instead of tabbing wire and worry about the tabbing wire later when I make the whole plane.

I have received all the equipment which I have bought. Tested them out. Works fine, except for the FPV. Before I go into the glitch/overlook, I will give you the list of equipment which I presently have.
All components:
Battery:
Turnigy 3S 2200mah 20C Li-Po pack x 2

ESC:
Hobbyking 60A 2s-4s ESc with 4A BEC

Receiver:
OrangeRx R61x DSm2 compatible 6 channel receiver

Transmitter:
OrangeRx T6 Mode 1 transmitter with 3 Position flap switch

Motor:
NTM 28-36 3000kv 2S-4S 366W brushless outrunner

Connectors:
Hobbyking XT60 connectors

Servos:
Hextronic HXT 900 9g 1.2kg torque servos x 3

Charger:
Turnigy Accucell 6 80w 2S-6S smart balance charger

Power supply:
12V 10A SMPS

FPV
Tx and Rx:
Skyzone FPV 5.8 ghz AV tx and Rx set

Camera:
Mini CMOS FPV Camera with 120deg. FOV (NTSC)

So, the problem is that I ordered a NTSC camera which doesn't work with PAL TVs used in India. What do I do?

Could I use an AV to USB converter and view it on my Laptop? Would that solve the problem?

Will post the solar cell test results in a few days.

Today I am going to solder the cells. Practiced soldering for the first time yesterday on the broken solar cell. What should I use as a load to test it?

Charge your batteries or run a 50w halogen bulb or run your motor.

@rcrcnitesh
Sorry for the delay. I soldered the cells yesterday. But I can't use what you mentioned as a load because the test setup of solar cells gives only 2.5V.

Some good news and a lot of bad news.
Good news:
Solar cells soldered and tested! Yes!

Solar cells' voltage is underrated. It gives more than that is expected.

I used four 1.2 ohm 5 watt resistors in parallel to have a current consumption of 20W.

V = I R

2 = 8 * x

x = 0.25

Four 1 ohm resistors in parallel = 0.25ohms.

I used the closest match as a load.


Neutral news:
Solar cell test results

Time Volts Amps Watts

7.00  2.14  0.42   0.89   Diffused sunlight readings
7.30  2.22  0.61   1.35
8.00  2.23  0.69   1.53
8.00  2.34  1.3     3.0    Direct sunlight readings
8.30  2.41  1.75    4.2

End of results

Bad news:

When I was measuring the current at 9.00, due to the wind, the solar cells were blown way. 3 out of four of the cells broke. I now own 1 good cell and the seller will send me a replacement cell for the one broken cell which I received.


Now I really do not know what to do.

Stats:
I soldered 4 of the cells together in series and checked the joints with a multimeter.

I soldered the four load resistors in parallel and checked the joints with a multimeter.

Results:
Though the sun was still rising, it gave more voltage than expected. Yay!

The solar cell didn't reach full power even at 9.00, when the solar cells crashed. I believe that this is because it was not under fully direct sunlight, which would take some time(the sun was still rising).


Question:

What am I to do now?

@karthick ashwath,
This is NOT a failure.
It is a STEP TOWARDS SUCCESS!
How many trials did Edison do before he got the light bulb to work?

What I understand from your test is that each cell can give 0.6v and nearly 2amps.
Is that correct?

So for 12-15 volts you need 20-25 cells in series.
And for 8amps, you need 4 such strips in parallel.
Or 80-100 cells.

What is the size of each cell?
How much did each cell cost?
What did you use for the tab wires?

Carry on. Do not give up!

OK sir.My parents too said a similar thing.
But I want to be more clear in presenting my findings.
1. I used monocrystalline 6x6 solar cells
2. I used multicore wire as the tabbing wire.
3. Actually, the cells would have produced even more volts and amps if they had survived till 12 o clock, when the sun is directly above the cells.
4.So, as of now, we do not know the actual capabilities of a single solar cell.

Anyways, it definitely is a step towards success as I gained experience in soldering. I also learnt from my mistakes.

Hoping to post the complete test results after the second testing soon.

Sir what can I do about the FPV setup? I have a NTSC camera but Indian PAL TV's don't support it. What can I do?

Would the problem be solved using an USB to AV converter and viewing it on my laptop? Or is there some other way?

I am in the process of acquiring new solar cells. Hope to post the test results in a month.

Hello everybody!

Some general info for everybody:
The website Vibrant hobbies no longer exists. It has been moved to rchyper.com (http://rchyper.com). I will buy my DT750, heat shrink and bullet connectors there.

I will also purchase an USB to AV converter to try fixing my FPV setup.

I will also purchase the solar cells required.

I will do all these things on Friday if the propeller issue is solved.
The problem is that:

I need to use a 12x3.8 prop. But I have searched some Indian online RC stores but I can only find a 12x4.5 prop. What shall I do sir?

Won't it(12x4.5 on DT750) consume more current? Can anybody test a DT 750 running a 12x4.5 prop before I buy one? It will be really useful to me.

v2eagle, I was wrong! The maxeon cells are the most efficient. I will test those too.
 
All the best everybody for the 6^th RC India sweepstakes.

Hoping to hear form you soon.

at the risk of inviting a flurry of calculations and internet data .....

use the props.

if you are worried about current ... use less throttle.

The simplest valuable advice you could get.
Karthick, check out the person who posted this advice.
You'll be immensely benefitted!

Thank you sir for your response. Thank you @saikat sir.

I also had another idea. What if we strap bottles containing hydrogen to the plane? It would give us extra thrust and we will need to spend lesser current.(just asking ;D)

The hydrogen can be produced from water through electrolysis.

I will go ahead with my plans.

@saikat sir, please check Reply no.169. Any solutions sir?

hydrogen and helium.
Both are bad.
Hydrogen- It is light and that's what makes it volatile. Can be use to create a mini Hindenburg disaster just by just using some static electricity.(the flames are not visible :o) (actually, Hindenburg was also filled with the same gas but yours would be a small tank.)
Helium- @ Words: Hard to find;Expensive.

So depron filled wings work well :p

 >:D

Well then, let's drop it. I'll continue using depron filled wings. ;D

Try using chemicaly expanding foam. Make a mould . And that would yield excellent foamy plane with lesser joints , weight and weaknesses.

But that would end up costing too much I guess.

But the expectations are also high . So a highly capable platform is needed.
What seems a bargain in plane's control and wing area . Is a quicky 300. That consist of 2 sets of wing .

http://upload.wikimedia.org/wikipedia/commons/a/a6/TriQ-200.jpg

Just increase the wing chords suitably.

 What do you want me to learn from that plane sir? Use the same design maybe?

Leave the foam expanding stuff.
just go with the depron filling route >:D  >:D

I mean u wil get 2 wings and more area for panels .

Yes, now I do understand. The Rutan quickie, the plane which Mathur sir recommended, is one of the most efficient planes in the whole world. It has 2 sets of wings, one low wing and another high wing.The low wing also has the landing gear fixed to it. I am very excited.

Maybe it is the perfect airframe for the purpose. Maybe it is.

But without scaled down plans, building it is not going to be easy. We will have to scale it down by ourselves.Let's try.

Try to obtain 3 view drawings and make up your own plans in sketchup.
There are tutorials on utube.

Hey ,
What are the flying charactersticks of that plane?
Be sure that when you build it,
 It does not become a aerobatic model.
You know; the cessna 150 is a trainer originally but as you convert is to rc ; it becomes a sport model .
This is because:
Suppose the real plane requires x density of air to fly as a trainer. If you scale it down; then the air density also has to be scaled down. But we fly rc planes in that same density air. This is (almost) the reason for real trainers to become rc sport planes.
First ensure that the plane you are building will be suitable for a beginner.
I am sorry if i have said anything wrong.
Regards

Karthik ,i am jus 18.
Back to question, just make 2 same wings. Make a nice fuse. Add rudder to it . Thats it.
Prabal my friend . I fear for what dual rates, end points and expo is meant for .

If thing really go bad , use a 401b gyro. 
always remember calm winds never make a great pilot.

i was thinkin' you guys were planning to scale down that same plane

Yeah i am talking bout the same plane 'rutan quickie '
its the building techniques.
I think depron shall be the right material for the plane. Though it shall need wing reinforcements. Experts correct me if wrong.

I presume that members offering suggestions have personal experience to validate whatever they are suggesting...

Uh oh i had already  made this plane but not rc it was meant to be a chuck glider  . What i made was a not perfect but did glided well.
Just one problem with this design is its cg position .

However this plane suits this project . But for sure not a first timer's cup of tea . In fact it took me 50+ chucks to perfect the cg.

So it is a difficult plane to build. Though it has high efficiency, its chord is small. If Burt Rutan has done something, it would have a purpose. I think that if we change it we won't be able to get that same efficiency. Maybe we can use this in the later stages.

Good news:
I have found an Indian online seller of depron. Its Rc Bazaar! Even the 12x3.8 prop is available there! Yay!

Bad bews:
I was not able to order the maxeon cells because they were out of stock. Maybe they'll be back in a few days.

So for now, let's settle for a simpler airframe.

@ karthick
are you still considering the big old foggy plane?
Check out the ft simple soarer. plenty of wing area. even though the wing has one break in it;
the plane is still considerable

I have mentioned the simple soarer long back. I think we need to scale up the plans for that. But anyway, lets try. First of all , let us consider the pros cons of everything and come to a final decision. I will post a tabular column of all the pros and cons tomorrow.

I am leaving old school as I am moving to Chennai. I like my old school very much and the people at my school also like me a lot. I have been saying things about my aeroplane for a very long time. So i wanted to do a live demo.

I have this Kfm - 4 aerofoil based flying wing which I built. I have planned the show on 24th of this month, which is a bit close. So I am in a hurry to get things done.

So I am going to make this flying wing my first plane. I have no other go.
The weight of the airframe and the electronics and the DT 750 is 950 grams

So I have selected the 9x4.7 prop which gives around 750 grams of thrust at 9.5A.I found that propeller and 3.5mm connectors on ebay for around Rs450 ( 2 gemfan props(genuine) and  12 3.5 mm connectors with heatshrink)

please advise me on my next step.

The problem with rcbazaar is that the 3.5mm connector is out of stock. All other connectors are out of stock. At RCB one prop costs 95Rs.

Solder them or check for ' rca female ' pin at local shops.

Have you tried rc hyper?

http://www.rchyper.com/4mm-easy-solder-gold-connectors-10-pairs.html

just .5 mm extra BUT the Shop is really good and so are its owners.
One of the best in india

@admin

Sir, will you please change the title of this thread from "Selection of motor for tern" to "Building a solar plane"

Thanks in advance,
Karthick Ashwath.

Here is the video of my solar cell test(6"x6" polycrystalline)
https://www.youtube.com/watch?v=bsWHNYtmAsU (https://www.youtube.com/watch?v=bsWHNYtmAsU)
Test results:
The setup is just the solar cell wired to a multimeter.
The voltage reading is fine. - open voltage is 0.6V
Short circuit current = 12A

All this meets the manufacturer's data.

So the actual power with a proper load will almost certainly be 4W.

More updates coming soon!

I have decided to change course and build a stock FT flyer with my electronics(DT750,2200mah 3s lipo,60A esc)
I will use depron instead of the super heavy foam I used before.
It is highly realistic and the expected AUW is 550g
I will be posting more updates soon.

Friend, it's not feasible.
A 2200 is heavy, dt750 is a overkill.
Go for a ft explorer.

I am going for the simplest plane. Wing loading is under 16oz/sq.ft.
Its running a 8x6 APC SF prop.

My avispad has a loading of 13 oz /sq.ft.
It will be a brick, friend.

Aerobatic planes have a loading of above 15 oz/sq.ft.
Why don't you go for maxeon panels?
Light, cheap and efficient.

Just tested the maxeon cells I received.
Volts- 0.624
Temperature- 32⁰
Amps- 0.6??
At first place, thought something wrong with my multimeter. Checked with various power sources, the amp reading is accurate.
The cells which should produce around 5-6 amps are producing just 600mA.
Looks like a defective batch. Has anyone worked with these before. :headscratch:

I have,
They work just as specified.
I used them on my solar plane.
It flew magnificently.
My batch was quite okay....
Further, I see that you have not connected the three sub-cells of the single panel in parallel together.

When I measured one, it was low.
Wire up all of them together, you will get 6 amps.

Did you connect them in series?

The three tabs of the cell are internally connected. I checked them with a continuity tester.

Just connect them even though that.
It just works that way. Don't ask me how.

Ok. I'll check it again ,connecting them.

Ok. Connecting the tabs together did not play any role in increasing the current. However after connecting 2 cells in series the output was around 1.6A. Maybe, this is happening due to the internal impedence of the multimeter. Looks like the meter is not able to calculate the current for a small voltage.

I connected 8 together.
Then was I able to get enough current

Yes I am planning to use maxeon cells I just wanted to test my own cell that I had.
Thanks for your data kiran sir.

How did you avispad fly?What happened to your solar project?What wing loading are you recommending?

Avispad (VT-SHR) is finished.
Two planes; a Pilatus pc6 turbo Porter and Stevenson's windy are being constructed.
My solar plane was completed ages ago. Won the second prize.
Wing loading is recommended to be below 11 oz/ sq.ft.
I am not so confident with my Pilatus. The wing loading is coming out 15 oz/sq.ft. That scares me.

Hai .... friend's any one tell me the difference between pull and thrust rating in brusless motor
..it make me confused

@prabal276,
Prabal, this is Karthick's thread.
Where is your own? Bump it.
Want to know fate of your Pilatus. Will post a pic of mine  ;D