RC India

Hello everyone, I chose Solar Airplane as my B.tech final year project. Started working on it from January and have time until may 1st week. Basically I'm from mechanical background with utmost interest in airplanes. So i have joined a team(sept 2015) which make planes for SAE Competitions abroad. Absolutely loved working and learning new things and learned as much as i can from designing to flying(less than 2 hrs flying experience). With this 1.5 years of experience in light weight rc planes and some research on solar cells i came to a conclusion that solar airplane is not an easy task.
            
      So instead of making a model and trying to fit solar cells on it I'thought designing a plane to fit solar cells would be a better choice. I have gone through this entire forum and found only 4 topics related to solar plane among which "new college project from PVA MODELS by Pradeep" and "coro flying wing by sbajare" found to be more informative :hatsoff:.  So with help of some rc experts like "K K Iyer Sir, Sbajare Sir, Anwar Sir, Pradeep Sir".......      i can make this project even more successful.  :help: I want to make sure that I'm going in the correct way.

Thanks in advance,
Aneesh.

I would like to help you in this project please let me know how I can help.

Aneesh.p,
Welcome to the forum.

Take a look at the thread 'selection of motor for tern'
It is long, 9 pages, 203 posts, most of which are not directly related to a solar power plane.
But there are a few posts containing factual data and/or raising important issues involved.
You may find them of some use.

Best of luck.

Thanks for the respose!
  That's indeed the first topic i have gone through in this forum :). I have selected the motor Emax Mt 3510 for this project using a 12X10 prop(is it ok to use small dia ,high pitch) and have done a thrust test .Regarding solar cells i have bought 30 sunpower C60 semi flexible solar cells (5000rs around) kept 26 untouched while done some testing and experiments on 4 of them, readings seems quiet reliable for small quantity but not sure about 24 put together. Chose an airfoil with minimum camber and sized the wing accordingly to accommodate 24 cells. thinking to finish this project in less than 30,000(team of three). Started manufacturing and its going good. Im not sure about how to connect solar cells to battery and motor ,and how to charge battery in flight :help:

@aneesh.p
If you are open to comments, here are some observations.


More observations/comments only if desired!
Regards.

Sir thanks for the reply! I came to know about this forum recently so i was left alone while designing the plane initially. I have made lot of assumptions while designing (don't know anyone to ask). I will try to answer from last question, please correct me if there is any mistake

why not 30 cells?
getting required type of cells in a short span of time puzzled me initially. After finding a dealer in hyderabad i initially got 30 pieces and thought to order more if required(don't want to waste) and those were very delicate and not conventional as others.so started testing to see voltage(0.55), current(5.1amp) with transparent sheeting , to know its extreme conditions of failure wasted 3 of them and kept one(slightly damaged) for further testing. Hence was left with 26 perfect cells. If i use 26 cells that would be without any spare, if some thing happens in between i cant get new ones(cells went out of stock  :-\) so kept 2 as spare and designed for 24cells(enough to charge 3s battery).
   I'm using 3s battery (for takeoff ) and calculated the cells to get 12v
   so 24X.55v=13.2v @5.1amp  (Testing were done in mid-feb, can expect more in april-may)
   Can accommodate more if necessary

Chose an airfoil with minimum camber (why?)
 each cell is 12.5cmx12.5cm sized (Considering 13cm with soldering gap), to fit 24 cells i need 24X13cm=312cm span with 15cm chord- manufacturing problem.
   So tried placing two cells chord wise ie two cells in a column giving 12 cells in a row so 12X13cm=156cm with 30cm chord. so gone for considerable minimum cambered foils to place two cells chord wise without flexing much(this is only one criteria in airfoil selection)
Added extra tapered sections to accommodate control surface,polyhedral and to improve performance

thrust test readings
since MT3510 is a multirotor motor its dynamic thrust has relatively less importance. After simulating (REAL FLIGHT 7 Simulator) a similar spec motor with different propellers i came to know that higher pitch propeller has relatively more dynamic thrust and was able to achieve a level flight at minimum watts. Hence decided to go for an higher pitch props and ordered 14x7,13x6.5,12x10
    14x7 -max 1158grms thrust -172W-14.4amp
   13x6.5-      930grms           -152W -12.7amp
    12x10-      1065grms          -169W-14A(found to be satisfactory)
    12x10-      500grms            -63.6W-5.1A(solar cells alone assuming)
    12x10-      400grms            -48.2  -3.9A
thrust test done with 2200mah3s,30amp esc and in pusher configuration,left at full throttle for a min and motor is slightly heated since it doesn't have any airflow
 I'm designing this plane for good level flight performance where it will be charging the battery and powering the motor simultaneously, battery is used as a backup(takeoff,sudden clouds etc)
 
Is there anything wrong or did i miss any thing in my calculations?

maximum plane weight 2kg trying hard to get it to 1.5kg
have done cfd analysis for this model stall speed(4.1m/s expected)
at 8meters/sec(level flight)  lift=1.8kg   and drag=.120kg (not sure in real though).

Thanks in advance,
Aneesh.
  

      
  

@aneesh.p,
Hi,
I don't know the basis on which you made your initial choices, but prima facie it looks like these are very good starting points, giving your project a favourable chance of success.
Before i mention why i think so, can we have an estimate of the payload?
102 g motor
  25 g prop est
  50 g Esc est
  68 g 4x17g servos
  30 g extension cables est
200 g 3s 2200mah lipo
Total 475 gms so far.
How much does each solar cell weigh? Total for 26-30 cells?
How much will the connections between the cells weigh (as they will carry 5-15amps)?

Hence estimated total weight of payload (ie, excl bare airframe)?
Regards.

Just a noob question , which is a better choice a flying wing or a conventional plane ?

conventional.
Flying wings. unforgiving for beginners

@Tanmay.mathur
Well flying wing will obviously be a good choice due to its performance and lack of integration but stability is kind of a problem(i dont want any crashes)
since i have 1.5 years experience in conventional i went for it  :)

@prabal276
exactly said ! ;)

The answer lies in the answer to these two questions:

1. What percentage of full size and model airplanes are flying wings?
2. Why does the Solar Impulse 2 have a conventional tail?

Unless one is thinking of foot launched sailplanes, most of which seem to be tailless.

Also on what one means by 'better'.
For some specialised applications, a flying wing may be better, but perhaps not in general.

Lack of integration?  :headscratch:
Sorry i couldn't understand that  :banghead:

@ K K Iyer Sir
motor+ xmount +prop+spinner+bullet connectors-close to 150 grms
esc-30 grms
using 6gram servo-rudder-t=1.2kg/cm
        9gm           -elevator-1.6kg/cm
        17gm         -ailerons-2.5kg/cm
control rods+linkage stoppers+screws=10 grms est
2200mah 3s-210grms
am using a separate circuit for rx and servos(in case some thing happens to main battery or ciruit)
1100 3s lipo-100grms
bec-15grms
reciever-10grms
extension wires-70 grms :'((need to find a way to get light duty wires)
solar cells 8g each so 24x8=192grms
tabbing wire 30grms(not sure about ratings but thats the same wire used in 100watt solar pannels so should work)
voltage regulator-40grms
sheeting-200 grms est
wings,tail manufacturing done-500grms around
fuse will finish by 3rd-less than 100 grms est
thats a total of 1.7kg est trying to get it to 1.5kg (a smaller battery ,ext wires,fuse)

will fly without cells first to see the throttle for level flight then with solar cells
Only problem so far is electronics circuit -how to manage charging while running motor simultaneously  ??? :help:

 

     

lack of integrations- i meant fuse-wing,fuse tail integrations ,attaching servo leads etc  :)

Do you mean you shall use a 3s lipo for rx and a bec too ?
Why not a 1s lipo + power bank circuit (step up regulator) to make 3.7v to 5v.

Would you use flaperons? Landing gear or belly land?
Curius bug.

@Tanmay.mathur
i dont have any 1s /2s and dont want to buy one just for one flight test  ;)
there will be 2 batteries one for propulsion and other for control

Its hand launched and belly landing, flaperons will give a try theres an option in my teams 6-ch transmitter ;D

I too was a curious bug thats what make us experiment things :thumbsup:

@aneesh.p,
Everything looks about right so far!

Wing size. Big enough to accomodate cells, but not so big as to be difficult to construct.
Aspect ratio. Fairly good for efficiency, but not so high as to be difficult to construct.
AUW. 17-1800gms, or 60-63oz. Excellent target that i thought would be hard to achieve. But looks like you will achieve it.
Wing loading. 7oz/sqft. Excellent. (Just have to be careful in strong/gusty wind). Hence stall fairly slow at ~4m/s. You can consider a slightly higher cruise speed than 8m/s (30kmph) to cope with wind)
Airfoil. What airfoil have you used?
I estimate that cruise will be at CL of ~0.7, which seems a reasonable initial estimate.
Reynolds number. Probably around 150,000 (much better than sub50k i often work in!)

Only 3 things remain.
1. I suggest a stress test of say +-3g for the wing.
2. Reconsideration of prop size, espcially pitch. 8m/s or 320"/sec with 10" pitch needs 32 rps, or under 2000 rpm. Please check if you get power/weight ratio of at least 1:3, or 1:2 for safer launch/climbout. High pitch prop will provide slower initial acceleration...
3. Solar cell maxWatts may be only 70% of maxVolts x maxAmps, or only 50% in less sunlight.

Would like to see your airfoil section and wing construction.
And i assume you have provided adequate tail volume coefficients and static margin in CG position  ;)

Excellent project. Solar issues can ba tackled after flight test on lipo.
Best of luck.

I could give a 1000 mah 1s or 2s if you need. U shall need a power bank circuit.
It could be very good setup (1s+step up)

Thanks tanmay
 meanwhile i will look around in my collage for smaller batteries
 thought its not must for initial flight test since i dont need to keep solar i will use only one battery

Ok let me know if you plan . Material for fuse and wings ?

@Tanmay.mathur
balsa and carbon fire entirely
ply for integrations :)

Balsa honeycomb ?
Is it expensive ?
Total airframe cost ?

@ K K Iyer sir
The data u mentioned is correct :thumbsup: :hatsoff:
cl-.69
reynolds num 143k at root and 95k at tip(i designed in such away that its near 1lakh)
included a -4 degree twist in end sections to improve efficiency and to increase stall angle(better stall characteristics)
Airfoil is we3.55(which u may not find in internet  -only mentioned in 2 journals so far-  its almost similar to s9000(9%) )
Tail volume coeff is .62+(considered losses in efficiency,manufac so kept a little high
Static margin is around 20%+(kept highly stable to compensate for gusts at low crusing speed)
Cg position can be changed have a lot of room in fuselage so thst sm could be brought to 10% if desired :)

about solar im not sure but im pretty confident on my design so it will be either solely solar powered or will charge the battery in glid(its a good glider) ;D

seems we think a bit alike have done stress test in last week for 3kg point load and 3.3 kg uniformly distributed
Tail weighs 109grms
entire wing weighs 370

Check out this youtube channel : https://www.youtube.com/user/rctestflight

point load (just want to see  :))

uniform load 3.3kg

added spars between foils to add stiffness and glued 1mm balsa sheets to make them uniform

this weighs 370 gms only-i didnt expect that ;D ;)

@sooraj.palakkad
I have downloaded that video in jan 
that video series gave me confidence and boost :thumbsup:

@Tanmay.mathur
its basic stuff nothing high-tech but proper planning
so far i hve used
3 3mm sheets
1 5mm
2 6mm
6 1mm
cf rods are expensive though around 2k+
50x50cm ply

regards,
aneesh

im thinking about fuselage
need to design
since im using a multirotor motor theres no space to attach spinner thats spoiling the shape of fuse
any ideas?

Diy foam spinner .
I make my own spinner by using my bldc as a lathe. Though not reliable so make  10 pcs and they cost ... Nothing.

Excellent idea will give it a try :thumbsup:

Thanks

Thankj

Will this work?

any idea in making of wingtips(easy kind)?

@aneesh.p
Hoerner if you are so inclined.
But initially, you can forget about spinner, wingtips etc, and other such cosmetics like paint scheme, wheels, LED lights etc, till test flights of airframe under lipo power, and then under solar power.
Whether you have a steerable nosewheel, or tailwheel or no undercarriage is irrelevant to the project, no?

 K K Iyer Sir
 Since this is costing me 30k around i will not fly the plane with solar cells connected. Basically i will fly with lipo to see how it performs and will note the throttle req for level flight and battery level after 10-30 min flight . After attaching the solar cells will leave this plane on ground with the same throttle level from 9am-3pm and will check the battey level-this will show that plane can fly wilth solar cells alone or can extend flight time when gliding
 projects aim is to extend flight time, so in any case my projects done.
But i have been plannig to make one from my second year so trying hard to make this fly with solar power alone-self satisfaction :)

meanwhile i made my fuselage today

Have a look at this link some very good details are talked about using Solar cells for a plane.

https://www.youtube.com/watch?v=JXpNnZUKnD4
https://www.youtube.com/watch?v=mS2UvS0Jb_8

regds
Saurabh

@rastsaurabh
Thanks for the links, i started my design after going through them. those were very good starting points ;)

finally the structures completed
weighs 530grms ;D ;D

super

good use of energy.

hello every one,
Got busy with clg reviews
mean while finished most of the plane
So far AUW with solar cells came up to 1650 grms(est)
structure weight is 650grms
Gona maiden this saturday

Best of luck,
Looking forward, for successful flight

How much trust is required for leveled flight?
Will T/W ratio of 0.3 work?

T/W ratio of 0.3 could work if you could generate enough initial velocity. Typically aircrafts with such low T/W do ground take-off. Hand Chuck is quite skeptical.

The best T/W I've personally achieved is a payload plane with an under-cambered aerofoil setup with a 1.4kg thrust electeonics and capable of lifting in excess of 1.5kg. But since it was a hand Chuck, payload had to be limited to 1.3kg

Sad news :my clg management didnt allow me to fly the plane seeing its size   >:(
 But because i prepared everything perfectly, i dont want to return back thinking how it would have flown or whether the cg and stability is good
So made a glide test
Will try to get permissions nxt time

Glide test video ;D

https://www.youtube.com/watch?v=_t9pdgBwn90

excellent video.
But why is it slow?

Video is slow because of slow motion feature in my cam -(kept that mode to analyze if something goes wrong :))
The plane is slow because it doesnt have propeller -the only force is the push i gave

@Aneesh.p,
Congratulations on successful test launch.  {:)}
What was the distance, real time duration, estimated speed?
Regards.

What about solar propulsion?

@k k Iyer sir
   Plane weighs 1330grms
   it flew about 92 feet(28m)
   airborne time is 9 sec

 

@sanjayrai55 sir
I hve used 2 batteries one for rx(1250mah 3s-90grms) and other for motor(2600mah 3s-210grms) so with these included my plane weighs 1330 grms
So instead of 2600mah battery i can use solar cells(230grms) which can give a static thrust  of 500 grms around

Which is more than necessary for leveled flight i guess :)
but might be a problem when clouded so using extra battery as safe side

From your video it seems it was just a powerful hand launch; no propulsion  :headscratch: ???

@sanjayrai55 Sir
Yes its just a hand launch
didnt connect the 2600mah 3s to esc but its inside the fuse

3m/s?
Remember your original estimate?
Looks like you didn't mount the solar cells.
So you are probably under 5oz/sqft.
Which is why you were able to save it so easily after the nose high launch,
And why she flies so slow!

Usually on test hand launch, we launch with the nose slightly DOWN, at close to the projected/estimated airspeed.

Would you like to do another test hand launch like this, to get some more data on airspeed and l/d?

https://m.youtube.com/watch?v=ie2thgI193A&feature=youtube_gdata_player

Caution: not a direct comparison. Mine was 48" span, 192 sqin area, 200gms (YES), AG03 at root, AG11 at tip (as accurately as i could carve them  ;D). 60m from sub2m launch, in 10-12seconds. Ie, 5-6m/s.

All in all, an excellent effort.
Do not stop. Just find a larger field. Chances of success are really good.
Regards.

@K K Iyer Sir
Really glad that you are guiding and correcting me in every step, Thanks for that :bow: :hatsoff:

I was afraid to include more weight because i dont have any practice in chucking and moreover it doest have propulsion to correct if any (Infact im only used to flying -this is the first time i chucked ;D)

Im not sure about Designed cg so made it a very little nose heavy and to counter that i have included a trim in tail-(thinking of the worse) coz i wont be having my hands on elevator initially
This made it climb hard up while chucking due to the more initial velocity i guess

Im not sure exactly how to know The whole Wing's Max Lift Coefficient correctly :help:
For now i used xflr software and max cl was found to be 3.4(dont know why so high)(Included a -4 degrees washout)
Wing loading for todays flight=5.916oz/sqft
With max cl of 3.4 Stall speed is 10.5kmph=2.91m/s(is it correct?)
Currently working on permission to fly and this will not be the final flight test :thumbsup:

Regards
Aneesh

@Aneesh.p,
CL 3.4 eh?

Yes, 1330gms on an 8sqft wing area at 3m/s does need CL of 3.4 for level flight

The test flight profile is clearly not in level flight regime.

I suspect that angle of attack is on an average in excess of perhaps +20deg, i.e., way past the stall.

For an S9000 type airfoil to be at the bottom of its drag bucket, the angle of attack has to be not more than about +5deg at the most. This should give you near level flight at about 6m/s.

I think what happened is probably this:
1. Based on tail volume, you have probably calculated the neutral point correctly, and then placed the CG to give a 10-20% static margin. So far so good.
2. Then, maybe fearing that it is nose heavy, you put in some UP trim in the elevator.
3. The launch was significantly nose high.
4. Launch speed was perhaps too high (Compare pre launch run in your video with mine)
5. Points 2, 3, and 4 together led to a deep stall
6. It didn't crash because you gave corrective down elevator in time, and because you have more than enough TV coeff and static margin.

A few suggestions for your consideration:
1. Check the decalage. More than 1-2deg may not be needed.
2. Hold the model lightly at the CG, in level attitude, i.e., not nose up. Walk/run into wind to get airspeed of around 6m/s. Do not release. See what it wants to do. If it wants to nose up, decalage probably too much. If it tries to lift out of your hand, without nosing up, trim is probably correct.
3. At this stage you try a hand launch. With nose pointing slightly below the horizon. Launch with a push if you are standing still, or walking one or two paces. If you are running, do not push hard, release with a gentle push.
4. Assuming a guess of L/D of 20, the flight path will be about -3deg to the horizon. If the model's attitude is level, the decalage of 1-2deg will give you an AOA of 4-5deg.

Wish I was there to participate in your tests  ;D
Best of luck.

thanks for that sir, I will surely follow those steps  :)

@Aneesh.P your hard work is really inspirational sir :)
:hatsoff: Iyer sir too

@a3ruz
 Thanks for that.  No 'sir' please i'm still studying ;D

A good news and bad news

Good news-
Got permission to fly but on a different field(no grass-only sand and concrete :()
included extra 300 grams to compensate for solar cells and circuit-AUW 1610
Initail battery level(2600 3s)-98% and 12.58v
Flew for 290 sec(5min around)
Its kind of windy today
because of the high pitch prop(12x10) my entire flight was in less than half throttle range ;D
throttle range for level flight is one point less than half on my tranmitter(JR XG6)

Bad news
landing would have been good if it would have been a grass fields
there was a sudden change in the wind direction while landing but managed to land the plane due to sand it bounced and slided into stairs of stadium :(, impact points are right aileron(servo gear damaged) and motor mount came off-every thing else is fine

After flight battery level is found to be 88% and 12.18v
which means only 260mah used(less than 40W) ;D

initial thrust test reading shown a thrust of 350 grms at 40watts will do it again to confirm
Will upload video by tonight its 780mb ;D

Regards
Aneesh

@Aneesh.p,
I presume that your emax 3510 is a 600kv motor,
That goes about 6000rpm on full throttle on 3s lipo, or say 3000rpm on part throttle.
Or 50rps.
So the pitch speed of a 10"/25cm prop is about 12.5m/s at 3000rpm.
Or more than twice your reqmt!

Would you care to try a prop of 5-6" pitch? (12-15"dia)

Regards.

Edit:
And if you are really flying at ~3m/s, Re is under 60k...

@K K Iyer Sir
I will do a thrust test with 12x6 next time and will surely share the readings

Frankly i dont know much about these propellers
i have gone for 12X10 because i have simulated in Real Flight7.5 software with different props and found that 12x12 and 12x10 takes the least power for a leveled flight

Is it good to go with 12x6 instead ?  Can you explain this part -im confused

@Aneesh.p,
Do not take others views (incl mine) as gospel truth.
Compare with your own experience.

Your first test revealed 3m/s.
I have explained probable reasons why it was so low compared to your original (theoretical) expectation of 6-7m/s (which i feel was a correct estimate)

What's the difficulty in matching the prop's pitch speed with your desired airspeed?
6m/s is about 20fps or 240" per second
If your motor is running about 3000rpm, or 50rps, how much pitch is reqd?
Ans: 5-6"

Right?

https://www.youtube.com/watch?v=tX-FT8_4SNk

Watch at 360p minimum to get clarity

@Aneesh.p,
Just saw your video.
EXCELLENT!

Looks like trim issues are sorted out.

Next you can try 30sec full power, then cut power to zero, and time the glide...

Here's a sample of what can be done with 20-22 seconds of power...

Will attach video in a minute...

Edit:
https://m.youtube.com/watch?v=C96oiT0ndgE

@ k k iyer Sir i got what u r trying to say

Reasons i got stuck with this configuration is
I have started this design based solar cells followed by motor ,props
So to prove the feasibility of a design i was forced to get motor and propellers even before i started designing(evenbefore knowing my wing dimensions)
and the recomended propellers were out of stock mostly except a  pair of cf1555 multirotor props which costs around 2k(same as my motor(2.5k))
and in the available props i got 12X10,13X6.5,14x7 based on simulator (i already have 12X6)
Didnt use 12x6 because i thought it may not give a static thrust of 1kg(thinking of my plane weight as 2kg -handlaunched)
and then used other 3 props for testing and i hve posted the reading in page 1

and one of the other reason i went for higher pitch is for its climb rate
Initially -one of my method to charge battery is to gain a maximum altitude within minimum time and gliding down to charge battery

But now since i have achieved the limits which i thought was difficult to get ,A better set of electronics can be found but money is a problem 
(in my initial calculations my weight is 1.8 -2kg) all my motor config is arranged for a 2kg plane

Im not a good pilot
Flew first time last feb and have got not more than 2hrs flying experience
The pilot who we used to fly with is in states now(will be coming back after 3months)
and dont know any good pilots nearby

So since i designed it i thought to fly it by myself
Landing damaged my fuse-it slided and hit the pillor  :( but happy that i got the video to prove my design :)
Fixing it will take some time and fixing solar cells and testing will take a whole week

My final review is on 11th may
so i will be having a week in between to contact as many faculties and companies out side to fund my project(this is costing me around 30k)
 
so only time i have is till this sat to do any more flight tests if necessary-My clg wont allow me to fly in good grass fields-and i cant afford any damage to my wings  :(

So this might be the last flight test unless if its necessary to do so
 

Looks as if you are going to stop, having achieved your MINIMUM target.
Are you just doing a college project, or attempting something not achieved earlier?

Come on, come on.
So far your attempt is the best combination of theory and practice i've seen on RCI in 3 years.

I will try repairing my fuse and will give the thrust test readings by tomorrow  
and seems like i need to start freshly on props :)


For best climb rate, esp at takeoff, fine (ie, low) pitch is used not high pitch
--I was initially thinking about maximum dynamic thrust while climbing at cruise speed-(less inclined fast climb)

Gaining max alt in min time means max use of battery
--max amp draw was 14 amps for 12x10 and for highest dynamic pull at least amp i chose 12x10 to gain altitude using minimum amp possible and thought i can charge the battery at 5amps rating while gliding-which can increase flight time-My projects aim

what limits? What difficulty?
I have never designed a plane of this size and a similar sized plane in my clg was weighing around 3kg+, so thought building a whole plane all by myself weighing half as the similar sized one is difficult to achieve
entire designing and manufacturing is done in my room with the help of my teammates
more over i started this project with a max budget of  :Rs:30,000 and to finish it as least as possible

Since there's a lot of work and money kept into it i was afraid to fly it (high chances that i may crash it) :(

All in all
Hope i should have joined this forum way ahead :) and will definitely consider on testing new props

Last flight test damage


Done repairing, this time it will be stronger i guess

Before flight

All that is reqd is some 1/16" or 1.5mm balsa sheeting on the fuselage...

like on 3 sides ?

will try that tonight
thanks

Any suggestions on how much throw to keep?

@Aneesh.p,
Elevator needs very little throw (assuming not grossly nose heavy), ~10deg each way.
Rudder needs more (as no ailerons), ~30deg each way.

@K K Iyer sir
After a lot of searching
I got only 12x6,12x3.8,13x6

i will do a thrust test tomorrow
Should i leave 12x3.8 ?

I used to practice flying on Real flight 7(software)
recently i have started designing planes in simulator and have tested my solar plane with different configurations whiled initial designing

After my 2nd flight test i tried simulating my flight test in software
with 125% turbulence and 7kmph winds i felt the same as flying in real

and since i have already had the battery reading of my 2nd flight test, thought to compare it with the software
Flew the plane same way and for the same duration :ie 5min

To my surprise its almost accurate
it flew with the same throttle level as in real
amount of battery left after real flight test is 2288 and in software its 2297 :o
and the watts for constant level flight is 35watt arounnd

have any one done this before?

real flight simulator
just edited the physics not visuals

After the 3rd flight test--flew wonderfully--and good landing too :thumbsup:

will start working on solar from tonight

will upload video by tonight

https://www.youtube.com/watch?v=or0v2NAvfFM

Excellent  {:)}

A few final suggestions:
1. Reduce aileron throw, as your ailerons are quite large
2. Add aileron differential
3. Mix 10% rudder with aileron

You'll be surprised at the improvement in handling.

Next project (before solar):
One minute climb at 80-100% power. Then see how many minutes of glide you can manage!

sir, thats something new i have never tried ,will definitely try  that

because we gona have our sem exams the labs will be closed by next week so for now we are concentrating on solar cells integrations and testing

any suggestions for testing?

 {:)} {:)} {:)} {:)} {:)} {:)} {:)} {:)} {:)} {:)}

Beautiful Aneesh. 
love the flight. it glides very well.

Thanks everyone :) :)

@aneesh.p,
Looks like you didn't see this
http://www.rcindia.org/rc-general-topics/solar-impulse-2-history-being-made/msg253177/#msg253177

I'm on it sir :)

working all day-solar cells attached ;D

Hope this gives the expected results

so any idea to attach solar cells to battery and to charge battery in level flight? :help:

@aneesh.p
Looks great!
12v x 8a = 96w
So should easily give 40-45w for take off / climb.
If your proposed ground test to estimate thrust is successful, try a short test flight without battery.
That will save you 200gms.
Tomorrow is Sunday, the scheduled day for all test flight...

(Learnt something new. That a hostel bed is a good workbench ;D)

From my 1960-70 knowledge of electronics, i expect that
1. You will need a diode to prevent the battery from trying to charge the solar panel
2. Your 24 cells (hope they are in series ;D) will probably not have the potential difference to charge your lipo to 12.6v

Come on all you electronics hotshot members of RCI, tell us what to do!

Meanwhile consider a test flight without the battery.

sir each cell is 3.33 watt @0.57 volt=13.68v max
i'm expecting 5 amps est around with this sheeting

i hve bought one10amp diode,a buckbooster
the circuit im thinking
cells-buck booster-diode-battery-esc-motor
battery will be connected in parallel with esc and solar cells


but dont know how to stop charging once battery is full
will this setup work? :help:

In my clg, ground will be full on weekends so flight test will only be possible on weekdays
moreover testing the solarcells might take 2days and ground testing for other 2days,permission for testings atleast a day :-\
so next flight test might take a week

solar charge controller should work best but a diode o-ring will be okay and will not charge the battery. Bench or ground test your setup before flight.

Sahil

Edit: and a lipo cell balancer circuit between the MPPT and battery.

rctestflight solar plane v2 is using http://genasun.com/all-products/solar-charge-controllers/for-lithium/gvb-8a-li-lithium-solar-boost-controller/

have seen solar charge controller(mppt) but the one that suits my project(genasun mppt) costs 10k so im going for some other alternative
any suggestions ?
i'm trying to finish this project as low as possible

This one of the most interesting projects I have seen on RCI! Congratulations on a successful flight and all the best for a successful solar-powered flight as well  :thumbsup: {:)}.

I can't comment on anything to do with the aerodynamics of the plane, being a multirotor guy myself, but I had a couple of questions/ ideas about the electronics. What exactly is the role of the buck/ boost converter is here? Is it to maintain a steady voltage from the cells? Another thing to consider is that the diode will drop your voltage by 0.6-0.7V. Since LiPo charging is pretty tricky, involving both a constant current and a constant voltage phase, I would advise against attempting to charge your LiPo in-flight, unless you are using proper charging circuitry. One idea that came to my mind is to use the LiPo as a backup power source and use a relay to switch between the solar cells and the battery. You can use a receiver control switch (Shameless plug - like the one I posted on my blog (http://www.fluxfpv.com/diy-receiver-controlled-switch/)) to turn on the relay. The LiPo will be connected to the NC pin and the solar cells to NO, allowing you to switch between them easily.

so what spec are you looking at?

yes the diode(rectifier diode) i have consumes 0.3watt .3v@1amp  -bought schotty diode (need to test)
i hve used buckbooster for two reasons
1-to get a steady voltage
2-to convert power either into a 2s or 4s

i did consider that charging a battery at 12v @2c charging rate would require-5.2amps -at less than 5amps my charging rates will be less than that

relay switch i hve heard from my electronics faculty-need to try one

@sahilkit

i hve some schotty diodes,
LTC3780 -buck booster

40 watt is my avg consumption for leveled flight
my pannels(if every thing works well) will give atleast 60watt(max 79watt)
so my battery would be charged at 20 watt --ie 12v @1.6 amps

if im running the plane for 6 hrs -i hope my current config will charge the battery with in 1hr but then i dont know how to stop charging

im looking for something similar to thermostat(im from mechnial) where it charges the battery when less than 12v and stops charging when above 12 v automatically

LTC3780 looks good as it allows VIN (solar panels) above, below or equal to VOUT, assume 12.6v or 12 v is used. Configure your solar cell to a Vmax of below or equal to 33volts with 3volt buffer (Wide VIN range: 4V to 36V Operation).

Assuming you have solved charging and cutoff please consider a cell balance charger circuit for safety and battery health.

Sahil

i will post some layout later.

thanks  :)

FYI http://www.linear.com/solutions/5195

tested solar cells-(between -11-12.30pm)
12..8-13.1v
3.8-4.2 amp

The cells are heating fast and due to that my sheeting got attached to cells and due to the extreme heat it started to shrink too
all these happened in a span of 10-20 mins

so decided to test only with some cooling(table fan maybe)

any suggestions?

have been testing solar cells past three day from morning 8am-5pm
greater than 40 watt for more than 6 hrs
peak 67 watt with just the wing
peak 47 watt with motor running


 

@aneesh.p,
Excellent.
Forget the lipo and fly on solar.
Try a 5 minute test flight.
It may turn out to be a flight of 2-3 hours!
I'm a believer...

Sir, i did run my plane today from 9am to 3 pm at 45 watt rating. Its a success  ;D

well done Aneesh.

https://www.youtube.com/watch?v=6eh7wBBfwbI

solar power alone

@manojswizera
  Thanks ;D

Wow ! Supreb sir ! :hatsoff:

@aneesh.p,
Waiting eagerly for test flight on solar power alone.
You can consider a small lipo and BEC to power the rx and servos, while the motor is on solar.
Regards.

@k k iyer
Sir, im searching for for good fields nearby to fly but so far i didnt find any. Moreover its my review time, so im too busy with documentation, signs etc etc.
Yes sir im using bec for rx and servos, u can see that in the last video i hve posted.
i will update once my review is done

Regards
aneesh.p

cant help but notice the solar panels on the roof on post 113 photo. is that your inspiration? anyways seems like the success is like a meter away and havent seen anyone from india going this far.. Good luck !!

Thanks ! ;)
those panels are used to power our dean's room-and no thats not my inspiration
i felt its more of a challenge to test my experience and knowledge gained over past 2 years in my team ;D
and definitely Solar Impulse 2 added a bit to it  :)

Regards
Aneesh.P


 

@aneesh.p,
Can you contact karthick ashwath via PM?

He thought of this project before you, but he is only 12 years old, and has no access to materials.

Your experience will be of great benefit to him.
Please help him if you can.
Regards.

Sir
   I have contacted him over facebook even before i started this topic here ,but no reply yet
   will try here

@Aneesh.P

Sorry for the long period of inactivity. I have replied on fb.

Hello everybody,
Please take a look at the two videos below. They are videos of a solar plane made by college students in Pakistan. Not to discourage anybody, but I am just saying that there are other countries in the fray too.
https://www.youtube.com/watch?v=tvQWnO7oDJ4 (https://www.youtube.com/watch?v=tvQWnO7oDJ4)
https://www.youtube.com/watch?v=Wizx5KHO0Xc (https://www.youtube.com/watch?v=Wizx5KHO0Xc)

They are also in a similar stage as Aneesh. We may be just be able to beat them.
All the best of luck Aneesh.
#teamindigo
#teamvimaanas

What about you? Your project?

Sent from my GT-S7562L using Tapatalk

Hmm i have seen that video
i think they used a 15x5.5 inch cf prop with a motor of 380-600 kv
with the kind of solar cells they used its tough to get a curved airfoil-so their airfoil must be flat
and im assuming the thrust they got is less as it was not able to move the standstill plane-did anyone thinks the same
and it seems that their wing construction is of high density foam( -wire cut -airfoil) with some cf rods or ply for strengthening --that should be really heavy for that long wingspan
Some of the solar cells are cut -(i have done this experiment)this reduces the efficiency a lot

if all my assumptions are correct and i doubt that this plane can fly with solar energy alone
But thats a great effort -soldering and placing those brittle solar cells is so hard
any other views?

It's not even sunny in the flight video... Foggy indeed....

https://www.youtube.com/watch?v=jZxzdWBuyyc
All in one version of my Project
Regards
Aneesh.P

Well done!  {:)}

wheres the final solar flight?
Regards
Good editing BTW

the ground in my clg is circular and small, with my experience in flying i cant turn this plane with out banking and if it banks more its loose power. so will try flying it only on good grounds.
more over im applying for competitions till then i thought not to take any chances -so no flight tests till sept mostly.

regards
aneesh

Great going Aneesh ....
Eagerly looking forward to the Solar powered Maiden ...All the very best ...
Regards

Sent from my Le X507 using Tapatalk

Here is another video of a team who have done a similar project. They have built a 100% solar flying wing that has flown for 6hrs straight. They have also charged their batteries during flight.
https://www.youtube.com/watch?v=rMkPjBf6dNQ (https://www.youtube.com/watch?v=rMkPjBf6dNQ)
https://www.youtube.com/watch?v=KHV-RjvTb1c (https://www.youtube.com/watch?v=KHV-RjvTb1c)

Congrats to that team!
All the best Aneesh!

I will also complete my solar project soon. Most of my hurdles(lack of availability of materials) have been broken!

Waiting eagerly for the solar maiden.

Warm regards,
Karthick Ashwath.

Hey; where did you get the cells from?
Regards

Sent from my GT-S7562L using Tapatalk

Prabal,

rchyderbad stocks them.

Ok. Cheers.thanks btw

Sent from my GT-N7100 using Tapatalk

Hi aneesh,
It is a good idea to mount solar panels on the plane. I have experienced some event which I would like to share with u regarding solar pannels. I had done some research on solar pannels and cell, my father brought a single solar cell which was 10cm*10cm. It was very thin, this was a single cell for which we had to solder wires. the cell suddenly slipped from my hand and fell down and shattered into pieces. All I want to tell u is that these cells are we're delicate. U get laminated stuf too but there generate less power due to the an extra layer. I could suggest u an another idea. U could put a brushed mother with a small propeller to it which provides less frictional force on both sides of the wings. This could be much more efficient on a glider.

Is there any update Aneesh P.?

Hope it help.... I have found that XXD's A2212 1000kv size motor is providing a 750gms of thrust with a 1045 size propeller.... Ya you can experiment it with prop having more pitch.... And one thing which is very important is that..... They are rated 15amps at load..... I checked with my 17amps power supply is motor is rotating at full throttle taking only 1.5 amps of current with 1045 prop.... You can use two motor.... Since you have plenty of power @5amps....good luck.... Im also a mech engineer hope i can help you...... Can you please tell from where you have got that Solar Panel?... I want same i have also another project.
Thank you.

Friend, look at the pages before.
Aneesh has ALREADY completed his project.
If you do care to read the above posts, you get a source for the panels too.
Brushed motors are too incapable.
I have also completed a solar plane and have won second.
I have talked to aneesh, his project is done.
Regards

Actually im viewing this page on moble device.... And who said i refered him to go with BLDC motors.... Nice if you have won 2nd... and who said brushed motor is insufficient?..... i have many highly efficient  Brushed motors(due to brush it is not as sufficient as a BLDC motor is))   which can do this job...

I never even referred to BLDC motors anywhere.
Yes, there are * efficient * brushed motors out there.
They are not in production so often now.
I mean you hardly find any brushed motor that can pull an 700 gms worth of airframe.
Better to go to brush less motor route.
Regards

@Aanishp
exactly solar cells are very brittle, in fact i broke 2 cells initially while testing. The cells i got are semi flexible (can bend upto 30 deg) and i kind of laminated them onto the wing(used transparent sheeting) which made them very durable-even though if the cell breaks, due to lamination it holds together maintaining the circuits inside giving an output.
   regarding a bldc motor- its a good idea, but with a gear setup. generally many bldc motors produce less thrust and may not be suitable for large planes particularly hand launched and for high climb rate  At the time of my project i was in a hurry and was looking in local shops for the best propulsion setup ( i have started with solarcells-propulsion-design-testing(in 3 months span)) so got on with what was there in the market. Moreover using motors on both wing might make the construction a little complex particularly with solar cells

@abhishek01
https://www.youtube.com/watch?v=D-eBnXrWJYw
this is a thrust test video of the motor you have mentioned
it takes around 10 amps to give 700grm thrust and at 2 amps it only gives around 200grms
it is sufficient to be used in my plane but using 2 motors (46+46grms) i can get 1400 grms at 20amps-which is almost the same i'm getting now(100grm motor-1.2kg@15amps) more over using two motors is complex as mentioned above (weights of extra mount,prop,esc ) and efficiency also goes down which might make a single motor setup a better choice

regards
Aneesh.P
   

Any update ?

hi.. I have successfully flown my plane. it flies very well during shiny days. check this out: https://www.youtube.com/watch?v=UWjAGPd4sRs

Well done. But do you have battery backup?

Specifications are appreciated.

to drive servo motors, some time cell voltage drops to 2.5V which is not sufficient for Reciever or servo.

i have explained specs and design in this video please have a view:
https://www.youtube.com/watch?v=tELccm2PIfc

 {:)}
Excellent achievement.

Interested to see its performance if the small battery is removed, so that it is purely solar powered...

Awesome !!!!

@ K K Iyer

Sir, I think he has used the battery to just to power the servos and receiver. Thrust is being produced by pure solar power.

Wow, Excellent. Good design.

Good Design!And Plane Fly really Well!!

Best Regards!

hello sir, My panels give around 4 volts which sometimes drops to 2.5V while turning. at that time receiver do not work properly so that I have used it just to control servo.

 {:)} excellent Built .

Jordar banayu che patel saheb

please let us know of any updates.