Hi Experts,

I have plans to make a cardboard based airplane. The expected weight of the final assembled device will be around 400-600 grams.
The airplane will fly only straight and in a circular path(tied with a cord to a center point i.e. NO radio control and servos and ESCs).

I looked around to get an idea of a powerful motor which can generate enough thrust for this device for a good flight. I got this link http://rcbazaar.com/products/159-odin-3800kv-brushless-motor-for-450-size-helis.aspx which talks about a powerful motor.
This motor is said to be capable of generating a power of upto 380 Watts. The motor weighs around 65 grams. The motor is supposed to be used in a 450 type helicopter. The reason I am interested in this motor is its cost?

Could you please clarify the below for me:
1) Can I use this motor in my airplane(which is not a helicopter)? If yes then what propeller and battery should I be using considering the final weight of the assembly?
2) What should be the wingspan of my airplane keeping in view the weight of the total device and motor power?
3) Apart from battery and motor, what else I might need for making my airplane work?
4) Any other inputs will be appreciated.

Thanks,
Nadia.

Cardboard i'm not sure, foam or coro will better. The motor you have pointed to is not suitable for three reasons 1)its a very high kv motor not suitable for direct drive 2) you'll need an esc to run it 3) very expensive for what you are trying to do.
A speed 400 brushed motor should be good enough and aim for weight less than 300 grams.
Also read this for some ideas:
http://www.rcgroups.com/forums/showthread.php?t=229024

Welcome to RcIndia, do read through "Beginners... Start Here" link at the top.

why don't you try to setup electric power on control line model? in fact i also started working on airplane "without RADIO" and so i choose control line before more than an year(pity-not giving dedication)...I'm trying something like bluebird (24" span), yet not complted  

Thanks for the reply.
Where do I buy speed 400 motor from? Any online store/link..

do you mean your batteries are not on-board?
What material have you used for making the plane's body?

@nadia
its soft balsa wing with hard balsa fuselase... as you said, "plan" for battery is not on-bord, but yet not finished

can i see a pic of it?

You can use this motor with a 3s lipo.
http://robokits.co.in/shop/index.php?main_page=product_info&cPath=2&products_id=208&zenid=ea772bafa630081cb6e28216c52c99f5
If you want to be able to switch the motor on/off while flying then you'll have to connect a relay between the motor and lipo. keep the lipo on the plane and power supply for relay in your hand. I think robokits.co.in have relays also.
Or you can have a cutoff circuit between the motor and lipo which will switch your motor off when the voltage is below 10v and you can land your plane.

[Admin Note] Unwanted "Quote" removed... use "Reply" instead... See usage guidelines : http://www.rcindia.org/rc-india-forum/forum-usage-tips/

Any idea about the weight of the motor?
I am planning to go for this battery
http://robokits.co.in/shop/index.php?main_page=product_info&cPath=13&products_id=68&zenid=ea772bafa630081cb6e28216c52c99f5
Would this battery be ok?

70 - 80 grams may be but i'm just guessing, better contact the vendor about it.
Have no idea about lion batteries so cant comment on that. Any ways it says 1C discharge which is too low for running a motor. you should get a 3s lipo, 350 or 500 mAh.

Thanks for the inputs.

I am a little confused about the battery. The battery and charger pair is one component which is somewhat expensive.

I will surely be trying more powerful motor in the future. Keeping this in mind, which battery should I go for so that I dont have to buy a battery pack again when I replace the motor?

Thanks,
Nadia.

 

I got a reply from the vendor about the motor:

1) The motor is an in-runner 12V DC and does not come with a propeller adapter. I need to buy a propeller and an adapter for that. I have never bought one before. Could you guys give me some link where I can order the propeller, adapter and related stuff? The spec of the motor says that the shaft has a diameter of about 2.3 - 2.5mm.

2) I saw a few posts on this forum and noticed that an in-runner motor may need a gearbox!! Will I need a gearbox too(for auw of 300 gms)? If so then which one should I buy? Link please if possible 

Thanks.
Nadia.

Thanks for the inputs experts.

I have ordered  this motor http://robokits.co.in/shop/index.php?main_page=product_info&cPath=2&products_id=208&zenid=ea772bafa630081cb6e28216c52c99f5.

1)I spoke to the vendor who said that I will need to buy propeller adapter for this. Could you guys advise which one should I go for?
2)Which propeller should I go for if the expected auw of my plane is 300-350 gms.
3) Will I need gearbox as well? If yes then which one?

Thanks.
Nadia.

Moderator note: Merged with your existing thread, please keep all discussion related to this project in the same thread for the sake of continuity.

The diagram on your motors page clearly states the shaft size is 2.3mm so that's the adapter you need. Get a 5x4 prop and you wont need a gearbox. There are lots of hobby shops you can buy these stuff from including lipo and charger. For the list of shops check the "Mega list of all RC outlets in India" thread.
ps: here is a suitable adapter
http://www.rcbazaar.com/products/247-23mm-jj-prop-adapter.aspx

I'm confused on few things since original post called for No RC
1) without Rx how will the esc power up the motor?
2) how does the material, being cardboard, provide shock absorbing capabilities to cushion the lipo and motor in a not-so-perfect contact with the ground?

Pankaj, its a control line model, no Rx and no esc. Check out the link in posted in reply #1.

Pankaj,

My fuselage will be made of light cardboard. I will surely place a supporting foam around the battery and motor so that nothings breaks(hopefully) in case of crash landing.

Anyways, I chose cardboard just because this is my first project and I want it to be as cost effective as possible. The first of mine is going to be a TEST ONLY model(understanding of concepts).  If the test flight goes somewhat ok, the next project will be to prepare a new model with esc, motor, servos and radio control.

But for me the first big thing is to see this light-cardboard plane flying using control-line. 

Cheers.

@SLS, didn't know that we could connect motor directly to the battery hence the question about Rx and ESC (still don't know about speed 400 though)

missed on this topic as it read, cardboard plane.....

regarding the c/l (control line) plane the motor you are suggesting is a 3 TREMINAL motor (3phase  AC), all brushless motor are the same, and the batteries we get to power the motor are 2 terminal (DC), hence we need the ESC to convert it as well as to control the speed. ( same as the throttle servo on a glow plane)

getting into C/L will be highly appreciated by me.. any help will be supported to u as best as i can from my side.

classically CL has to have a engine with specific amt of fuel in the tank which will decide the flight time. and you will have no throttle control.

but since your idea is of electric. you can go ahead with it also.  all you will need now is a DC motor/ brushed motor which will act as ur engine  and a small capacity battery which will act as your tank. keep the battery capacity less or you will end up turning whole day.

and for the control of a control line :
CL has only one axis controllable i.e pitch, as it circles you it has no turning (roll or pitch)
you will need two lines in your hand one for up throw and one for down ( understand form the drw below) which will be connected to your handle . pulling one line will make the nose pitch up and other pitch down.

whn you pull line1 the elevator pitches up, and line 2 pitches down (connect pushrod to a control horn to the bottom side of the elevator..!) pic of handle also enclosed.)
hope u can understand the pic.... any quries are most welcomed .. ( my ph no is  in my signature)

Please read the complete thread, the motor we are talking about now is a 12v DC brushed motor.

sorry missed on that... any ways for rest all it looks good.!

I have looked on rcbazaar and robokits but still not able to find a suitable li-po battery for my motor.
could you guys provide some online link where I can order this battery? I am looking for a lightweight battery.

this can be used..!
http://www.hobbyking.com/hobbyking/store/__7292__Rhino_750mAh_3S_11_1v_20C_Lipoly_Pack.html

I received the motor yesterday through courier. To my surprise the weight of the motor is nowhere near to what the vendor claimed.

The actual weight is around 125-140 grams. A big challenge now for me is to keep the auw of my plane to a minimum.

If the motor and battery assembly itself weighs more than 200 grams then its difficult to keep the auw to be less than 400gm(this is the min I am assuming). I have no prior knowledge of aerodynamics. Can experts please advise me about:
1) How much the wingspan & wing-area should be
2) What should be the length of the fuselage?


Thanks for the help guys.

Hi,

At the moment my project is a control line-one but I would like to promote it to wireless radio once it is working.

1)I would like to go for the cheapest radio controller and recievers. Could you guys please guide me about this?

2)Also, I am a total newbie to flying. How can I get access to a simulator to learn flying?


Thanks.

Yesterday I received propellers, adapter from rcbazaar.

Please see the attached pic for propeller adapter. I ordered on 2.3 mm adapter. I belive rcbazaar has missed sending me the screw to tighten the adapter shaft on the motor shaft. There is one hole on the adapter shaft(as marked by arrow in pic) but there is NO SCREW!!!

I am in search of a tiny screw at home which can fit there. Is there any other way of installing the adapter on the motor shaft?

Thanks.

Yesterday I received propellers, adapter from rcbazaar.

Please see the attached pic for propeller adapter. I ordered on 2.3 mm adapter. I belive rcbazaar has missed sending me the screw to tighten the adapter shaft on the motor shaft. There is one hole on the adapter shaft(as marked by arrow in pic) but there is NO SCREW!!!

I am in search of a tiny screw at home which can fit there. Is there any other way of installing the adapter on the motor shaft?

Thanks.

nadia, it is called grub SCREW look carefully, what you think is a hole could be a SCREW , it is a SCREW without a NUT (Very rare but true)

Thanks for the reply augustinev.

I think you are spot on. There is a hole on the adapter shaft but I cant look across it because its black from inside. Because of this the motor shaft is not going in. Could you please tell me in detail how to install the motor shaft into this adapter? Which screw-driver should I use?

Thanks.

Dear nadia, i would first prefer to look at the hole carefully. U may also use a torch, and you will get to know what type of screwdriver you need to loosen it.

Secondly, if you havent started your build, ill prefer you to change the material.. I have used several materials for planes(Free Flight when i was unaware of this forum), cardboard was one of the worst material i found. Reasons:
1.It was very difficult to join using any material. Even good joints break as it is made up of fibres, which are not very strongly bonded to each other.
2.Cardboard cracks,loosing its stiffness if you want to bend it in curves.(I failed during making of airfoil)
3.Its much heavier than other cheaper alternatives available.
4.Finally, repair to cardboard planes is much difficult, and you will feel like giving up soon.

 

You need right tool for the right screw, do you have a  Hex Screw driver, have you heard of Alan Key ? very small one will fit in it, get it form a hardware shop. happy screwing

Thanks a lot augustinev

It was indeed a grub screw and its hex shaped head was too small to be noticed from naked eye.

I have now fixed the adapter shaft onto the motor shaft. But a few older posts in this forum suggest that the motor shaft chould be flattened a bit(using a tool) for better grip. is that true?

I have ordered 3s lipo from HK but will take 2 weeks to arrive. Is there any way I can test the motor attaching with cellphone batteries, 12V DC adapter? I am curious to know how much thrust my motor can generate.

cheers.

Wrong "thread"!

Where can I find depron and foam dealers in delhi.

Is it sold at stationary shops?

depron goes by the name of BioFoam in Delhi, you get it in Pahargunj area - look for Gokal Chand in some of my earlier posts for exact address

Hi,

After a little research I have got hold of 2 24"x24" coro sheets. I was trying to get 36"x24" but coro sheets are available generally in 2x2 only.

As this is my very first airplane I have tried keeping things very simple. I have come up with a simple plan with the help of which I can cut the coro sheet to give it a shape of an airplane. Please see the attached image for details(The measurement are just indicative, not accurate).

Details:

Wing span        = 24 in
Wing chord               =  8 in
Length of fuselage   = 20 in
tail                  = 10 in x 3 in (approx)
vertical tail              = ??(not decided yet)
planned AUW      = 300-350 grams

The motor I am going to use is a brushed speed 400 motor with 3s 11.V 20C Lipo.

I have read a few other posts for understanding of basic aerodynamics . The problem I see with this plan is that the angle of attack  is going to be zero as the fuse and the wings are going to be in the same surface. Is this really going to be a problem? The motor I am going to be a brushed one and is not expected to produce much power. Experts, please let me know your opinion?

Thanks.

Nadia! Keep the angle of attack as stated in the plan.As the angle of attack is increased, your plane will keep going up continuously, and also increase drag, ie; more thrust required to achieve desired speed. I mean your plane wouldn't be able to fly level. Continuous pitch inputs will be required then. However in RC planes, it is desired to have or not have angle of attack more than zero.
Keep the wings level with respect to the fuselage(As you shown in drawing). Don't worry.

I request senior members to correct me if I am wrong.

Thanks.

350 grams AUW on a 24" wingspan?  Have you calculated wing loading?  Seems ot me to be on the high side which means you want this to fly like a warbird, not floating in  gently or slow flying? 

The specs of my airplane(to be) are (all are approximate):
Wing span = 40"
Wing chord = 8"
length of the fuselage = 24" without adding tail section
horizontal tail =  The area should be around 70 sq inch
vertical tail = I have not started this yet and need expert advice for this. My coro boards are over. I may have buy new one for this.

When I started on the build I thought it will be easy to keep the weight under 350 grams. But I now fear that I have crossed this limit especially after the introduction of cycle spokes(4 for dihedral and 2 for landing gear). I have not weighed the overall assembly but my gut feeling is that it will be a little less than 500 grams. I am using a speed 400 brushed motor with 11V Lipo. I used a 7x5 SF propeller from HK. The motor and propeller combination is generating about 280-300 grams of thrust.

NOTE: I intend my model to be either a free flight on or a control-line one. I dont have any wireless things at the moment. So I am saving weight there.


****************************
Build log:
****************************



I have started the build and have finished a few things. Attached are the pictures of what I have tried building so far:

I have not followed any plans but have tried copying others on the forum. My airplane is a pretty simple and basic design.


PIC1) In order to add a little dihedral to the 2 wings I have used 2 light weight cycle spokes(1 made by welding 2). length of each will be 24". As the platform I used a lightweight hard cardboard ruler. I used epoxy to fix the cycle spoke between 2 plates of cardboard ruler pieces having straight grooves. As a result the wing now is a separate unit and is completely removable.

PIC2) I made wings in a hurry. Each wing is profiled by three pieces of dense thermocol each 7" long. I made the profile curve on the thermocol piece by sanding it. To join the wings and thermocol I have used strong double sided tape. There is visible difference in the profile of wings. But I cant help it anymore.

PIC3 and PIC4) This is how I intend to make my airplane look like. The wings would be removable and could be fixed with the help of rubber bands.

PIC5, PIC6 and PIC7) This is a lightweight landing gear. I made this by hammering 2 light cycle spokes into a soft wood block and then applied a little fevicol and fixed it. I made a groove on the wood block so that the cycle spoke does not move in either direction. I have employed wire insulation and electric tape so the wheel rotates smoothly and straight.

PIC8) i tried giving the tail a little profile by folding the corner part onto the centre. Experts, please advise
   -(i) Do I need more tail area?
   -(ii)Should it have a profile at all?

PIC9) This is my motor mount which is screwed on a piece of cardboard ruler and then onto the base of fuselage. I have used a lightweight aluminium holder which has 2 screw points.(In the picture I have a dead weight attached in there at the moment for flight tests. Please ignore that.)

pics continued...

pics continued...

Consider the RC option.  Going free flight is kind of risky considering all the work you've put in it.  At least try 2 servos (rudder and elevator). and the Hobbyking TX/RX.  Vineet may have one for you.

If my airplane has 280 grams of thrust and 500 grams of weight, will my model fly? Wing span = 40, chord = 8.
An earlier post says we need 60% to 70% of thrust(relative to the weight of the model)  to fly.

If not then can the experts please pass on suggestion about reducing weight of the airplane?

Thanks.