Electric flight in a 27" Wingspan Plane?

[Ladders]

HHHi everyone!, having a few problems posting at the moment!!

Edited By Dave Ladkin on 08/11/2011 21:31:40

[Ladders]

Sorry, couldn't type in the topic box properly!

 

I've got a 3/4" to 1'0" scale, 27" wingspan balsa Mustang I'm currently building. It's pretty small and in the past you would only hope to power it with an elastic band or Cox Pee Wee. What I'm wondering is with how things have moved on, is it possible to build with electric power?

 

I'm half way through, and would like to know if this is possible before I finish it?

 

I was thinking motor, and possibly rudder and elevators as well? I'm interested in doing it as a project so don't mind if it's going to be a hasstle.

 

What sort of size and power engine will I need? What servo's etc?

 

Thanks for any help!

 

Dave

[Dave Bran]

Yes, it's perfectly possible. Keep it light. What weight do you expect to finish out at?

[Ladders]

Hi Dave. I'm not sure really? If I get all the bits together and weigh them will that give a good enough idea?

[Simon Chaddock]

Ladders

Yes a description of what you have got and its weight can give a good idea of the likely finished weight but you do need to keep it light, very light.

Small planes react quickly enough as it is so the lighter it is the slower it flies and the more time you get to sort things out.

Try to avoid entering the weight/power loop - more power to handle the weight but the extra power also increases the weight.

With rudder and elevator you would be well advised to increase the dihedral.

 

My own choice would be elevator and ailerons "bank and yank" with scale(ish) dihedral but with no rudder its is difficult to keep straight on a ground take off.

[Ladders]

Thanks Simon. I've built it with extra dihedral as I wanted to do this from the start. I was going to cover it in traditional tissue and dope, but without painting, but would I be better to plastic cover it? I wanted to display it as well, hence the tissue route.

 

I suppose you can't recommend any kit yet until you know the weight!?

[Erfolg]

There was a thread on a conversion of a very small Spitfire, to electric.

 

From what I remember, it supposedly flew (I have no reason to doubt that it did not).

 

I have seen a number of sucessful small models and as been suggested, they need to be light, if moderate speed is sought. Surprisingly the best ones are those pre made foam jobs. As to conversions, they do seem to be a problem, as designed, the envisaged flying speeds were low, hence landing/crash speed was also slow. Stick RC gear in and suddenly the wing loading has gone sufficiently to require a highish speed to keep them airborne. So the RC gear benefits from the actuator type systems, that is extremely light. Although the wing loading may seem low, due to scale effects, it can be quite high relatively when compared to a larger model of the same loading. There is a formula which links flying speed to model/bird size (unfortunately I cannot remember it).

 

Yes doable, requires the right kit and careful building.

[Ladders]

Thanks Erflog, I'll have a search for the Spitfire thread

[Ladders]

I've just found this thread

 

http://www.modelflying.co.uk/forums/postings.asp?th=50664

 

I suppose it would have helped if I said it was a Guillows kit etc! Anyway, I'll have a watch of the vid and see what I can pick up!

[Ladders]

Ok, put the bits on the kitchen scales and I'd say it roughly weighs 100grams

[Simon Chaddock]

Ladders

Tissue and dope is probably still the lightest stiffest covering. The plastic films are heavier but much more rip and puncture resistant but their very flexibility means the basic structure has to be a bit stiffer to start with.

 

Will your Mustang have and undercarriage?

Small planes require a really smooth surface for take off with scale size wheels. There is a lot to be said for hand launch/belly land with no undercarriage.

 

Any pictures of it so far?

[Ladders]

I was going to have an undercarriage?

Just trying to add some, do I need to upload to a picture hosting site and do a link?

[Ladders]

 

Still quite a bit left to do! I've been waiting for ages to find out what I could do and decide which way to go, so it's been at this stage for ages.

 

 

 

I thought using paper would be stronger than tissue, but weigh less than balsa.

 

 

I've fitted the struts so I can use some sort of under carriage.

 

 

 

I was going to use paper on the fuselage as well to strengthen, and then use elastic bands to hold the wings on?

 

[Simon Chaddock]

Ladders

Very nice work with the tissue but a Mustang? Surely its a Curtiss P40!

With that amount of balsa in the fuselage I would stick to a tissue covering. Paper is a lot heavier.

Which brings on the next problem of how to actually install the radio control gear and battery. There doesn't seem to be any access to the inside the fuselage.

 

At this point I would just complete it as a Guillows 'show' kit and build/buy a much simpler RC plane for your first electric RC.

[Ladders]

opps! I stand corrected!

 

That was part of the challenge for me, to see if I could convert it.

 

Any suggestions for what motor etc I'll need.

 

What would be a good kit for a proper RC plane? Nothing to big though.

[Stephen Jones]

Hi Ladders ,

 

I also converted a Guillows P51 to Rc control and i used Brown paper and Poly C to cover mine here is the tread and video Link to How i Used Poly C Hope this Helps .

I made my under carriage for static display purposes so made them detachable .

 

Edited By Stephen Jones on 11/11/2011 14:32:28

[Ladders]

Brilliant! Thanks Stephen. I had a look at your video from when I did a search, I'll have a look at you thread in a bit. Amazing how manoeuvrable it is in flight!

[Stephen Jones]

Yes loops and Rolls no problem ,but as i did not fit a working rudder no stall turns or spins .

 

But still an interesting Hack . which can be used as a static displayed model .

[Ladders]

Did you not have enough room for the rudder?

[Stephen Jones]

No i was worried about the weight and as i had used two 9grm servos i thought it best to leave it on just elevator and Ailerons .

 

I could have used 5grm servos instead for all control surfaces but all i could get at the time was the 9grm ones .

 

[Stephen Jones]

Hi ,

 

Just to let you know Rc flight is also possible in a 24" model.

 

As this one i made .

[Ladders]

Is this the type of motor you used Stephen?

 

http://www.rcmodelcentre.co.uk/KMS-Quantum-2212/12/prod_203.html 

 

What receiver and batteries etc did you use?

Edited By Ladders on 11/11/2011 16:51:27

[Stephen Jones]

Hi ,

 

I`ll take some photos later as the motor , i think is no longer made there is a similar one on big fish a 2208/12 but the picture they use is also wrong .

 

I used , Motor 2208/12 , 12amp Esc , 7 x 4 Folding Prop ,

Two 9grm servo and a small 35Mhz receiver .

 

[Stephen Jones]

Hi ,

 

Shame on me its taken so long to get a picture

 

Here is a picture of the motor and mount also i forgot to mention that i set the motor with 3 degrees of right and down thrust

the motor is a bl 2208/12 driving a 7x4 folding prop on a 800ma 2s battery gives me 50 Watts .

Just for comparison the motor on the bench is a 1510/22 which is for the 24" model which gives me 30 Watts of power on a 5x3 prop and a 350ma 2s battery .

 

[Stephen Jones]

Here are some more picture of wing servo driving the ailerons .

On the one above i have used wire and bell crank to drive the elevator and a snake to drive the ailerons .

this one show the servo arm sticking out the side of the fuselage for the elevator .

 

Good luck with your build keep us posted