Part picking for 250g or less fixed wing

[Boatmans]

Hello I am getting back into RC planes and apparently I've missed a lot. I used to fly the big gas powered RC planes with 27 MHz transmitters and no autopilot features.

I want to build a flying wing fpv under 250 g. I would like it to have a long flight time. I need efficient motors but they have been hard to find. I'm hoping to do a 2s or 1s to save on weight. But I'm having trouble finding parts. So I guess my first question is can anyone point me in the direction of a 1-2 s electronic setup for a flying wing? Or store that would have what I'm looking for? 40 location where I can find more information on efficient motors? A lot of the motors I look at don't have any thrust data. Are there any brands that are known for having very efficient motors? I found a couple that have a 10g/w rating at 1-2 s but I'm sure there has to be more. And those motors are designed for quadcopters not planes. But they should be fine?

Hoping to have a receiver plus ESC
I found some efficient motors that run at 11500KV but haven't found any esc's that can push that speed.

I would like the ESC to use field orientated control but not all producers are publishing control scheme information. Might just make my own... It can't be that hard.

Is wing warping a good idea? I was going to reinforce the wings with a carbon fiber rod so I could just apply a torque to that and that should warp the wing. Would definitely help reduce drag does. anyone tried this approach before?

I would like to power it with lithium ion batteries that are flat and normally used in laptops. Should be able to tuck them into the wings pretty nicely. They should offer double the energy density of lipo. The only issue is maximum current draw with them be limited to roughly 5 amps. But from my calculations that should be pretty easy to achieve. I will say I'm not the best with Reynolds numbers and drag coefficients.

I also have the idea in my head that I'm going to 3D print the body of the plane. I have some pla plus which offers just enough rigidity and flexibility. And I have been able to print spars and ribs into the solid model. That was not really a question I'm just looking for opinions.

There's also the question of fpv which I have not started researching yet.

It also be really cool if it had a pix hawk for autonomous missions. but I haven't been able to find any ones that are lightweight enough. I guess I would also need a gps

Sorry if this is in the wrong spot. First post. I have a million more questions so

 

[flyingkelpie]

For a wing, you could try the FT Mini Arrow which is around 175g. Nowadays you can just chuck the FT power pack A or F into it and off you go! For a battery, I would use the same specs but get a more reliable brand. Some would disagree with this but I prefer Zippy, Turnigy or Rhino batteries. If you run the right Power pack in the right FT plane then you will have fine performance. As for wing warping, I would stay away from it because it would cause the foam to lose its strength over time. Also 3d printing planes is really cool. Here's a FT video on a 3d printed flying wing:

FPV is kind of expensive if you want quality. Especially for the goggles. However, I've just found a good one for cheap because its discounted: Quanum Cyclops. As for the camera then maybe this one here will work. As for the mounting and all the other electronics I really don't know. Hope this helps!

 

[Matthewdupreez]

man I wish I could afford that fpv goggle

 

[JasonK]

I want to build a flying wing fpv under 250 g.

sounds like fun, the FT dart and FT arrow both work well for this, the picture from my PFP is sub 250g and i get ~10 min of FPV flight with a 3s 650mAh lipo

I would like it to have a long flight time. I need efficient motors but they have been hard to find. I'm hoping to do a 2s or 1s to save on weight.

how long is a 'long flight time' to you? do you want it to have a greater then 1:1 thrust ratio potential?

I think your making a mistake here, for a given energy capacity, the mass is fairly similar for a given battery tech. for example a 2s 400mAh and a 1s 800mAh lipo will both have the same amount of 'juice' in them, and weigh basically the same. however the 2s will give that same juice at 1/2 the current, meaning less voltage sage (power loss due to internal resistances).

And those motors are designed for quadcopters not planes. But they should be fine?

the only thing I see about a quad motor that would be different, is being designed to be better at changing speed quickly, as that is needed for the flight stabilization.

I would like to power it with lithium ion batteries that are flat and normally used in laptops.

again, here is where a higher s, lower mAh batter pack can help, as you can get the same power output for lower current draw by having a higher voltage

I also have the idea in my head that I'm going to 3D print the body of the plane. I have some pla plus which offers just enough rigidity and flexibility. And I have been able to print spars and ribs into the solid model. That was not really a question I'm just looking for opinions.

3D printing is going to be more massive then foam, if your goal is sub 250g, I would avoid it for the wing/etc, but it may be useful for control horns/etc (but might still be heavier then hobby plywood and the thermal aspects can make it a poor motor mount if your motor gets hot)

There's also the question of fpv which I have not started researching yet.

if your in the US, your going to need a HAM license for 99% of the video TXes out there (and the ones that you don't are really low power - ie almost 0 range)... I am not sure if the DJI stuff requires a license or not, but it is one of the most expensive options and one of the heaviest on board options.

It also be really cool if it had a pix hawk for autonomous missions. but I haven't been able to find any ones that are lightweight enough. I guess I would also need a gps

get something like a F411-WSE which weights only 8.5g

 

[flyingkelpie]

man I wish I could afford that fpv goggle

Same! I would like to get into fpv but...you know how it is.

 

[Monte.C]

Hey @Boatmans!
I was asking similar questions recently. You might want to read through this thread:
https://forum.flitetest.com/index.p...stion-for-quad-people-tiny-motors-escs.65542/

I wound up with a good set of electronics. My next build will utilize all of it. I have two 1106 quad motors so I can run on one or two motors. Two little speed controllers, I think 16A, really small servos. I can check exactly what I have when I get home tonight if you want.

I think sub-250g is harder than it looks. I don't care about the weight, but I've been downsizing my builds just by preference. Dollar General sells a tri-fold display board only 3mm thick, and I think the Dollar Tree FB is 5mm. This next plane will be small & delicate.

 

[Boatmans]

This is all very helpful thank you everyone! Lots of good ideas. I may forgo the fpv then if it's going to be expensive for the time being. Maybe once I get the plane operational I'll look into it.

Some clarifications:
I live in Canada. And the law here is as long as the drone is under 250g then you can essentially fly it wherever as long as you don't put people or property in danger. Oh and needs to be line of sight. And for my first forte into the new RC world I figured 250g is a good benchmark.

The idea is I want to be able to soar around the local park and adjacent neighborhood and just taking the sites for as long as possible. But maybe I could just return and swap batteries and keep flying. But that is a very good point about the power density with 1s and 2s batteries. They all have mAh when they should have Wh

 

[quorneng]

Boatmans
It may sound obvious but building sub 250g requires a good understanding (experience!) in both the strength of materials and structural design and we are not talking steel or aluminium but light materials like balsa and foam. By comparison the 'electronics' are less of a problem as they can be found very light already.
Following this philosophy I have built several sub 250 g planes primarily just to see if I could and how well they might fly.
This is the latest. A powered RC conversion of a simple foam chuck glider.

Bigger than it might look with a span of 1340 mm (52.6"). It has 3 servos (ailerons and elevator) and weighs just 198 g with a 950 mAh 2s on board so well under the limit.
It is all foam (no wood or carbon reinforcing) although its new centre section is a built up hollow structure using a denser foam.
The big disadvantage of such a plane is it flies so slowly that suitable calm days are few but in the right conditions it can do so for well over 1/2 a hour at a time.
Perhaps a bit more practical is this 1100 mm (40") span Super Cub with its weight write large on the wing!

This time all built up from thin (2 mm) sheet foam it uses a 1000 mAh 2s and with four servos to include the rudder.
Obviously more to it than a glider but it manages an easy 15 minutes and is aerobatic.
Still needs pretty gentle conditions but get it into a thermal and you have to be careful not to loose it.
Long live 250 g

 

[Monte.C]

Boatmans
It may sound obvious but building sub 250g requires a good understanding (experience!) in both the strength of materials and structural design and we are not talking steel or aluminium but light materials like balsa and foam. By comparison the 'electronics' are less of a problem as they can be found very light already.
Following this philosophy I have built several sub 250 g planes primarily just to see if I could and how well they might fly.
This is the latest. A powered RC conversion of a simple foam chuck glider.
View attachment 186552
Bigger than it might look with a span of 1340 mm (52.6"). It has 3 servos (ailerons and elevator) and weighs just 198 g with a 950 mAh 2s on board so well under the limit.
It is all foam (no wood or carbon reinforcing) although its new centre section is a built up hollow structure using a denser foam.
The big disadvantage of such a plane is it flies so slowly that suitable calm days are few but in the right conditions it can do so for well over 1/2 a hour at a time.
Perhaps a bit more practical is this 1100 mm (40") span Super Cub with its weight write large on the wing!
View attachment 186553
This time all built up from thin (2 mm) sheet foam it uses a 1000 mAh 2s and with four servos to include the rudder.
Obviously more to it than a glider but it manages an easy 15 minutes and is aerobatic.
Still need pretty gentle conditions but get it into a thermal and you have to be careful not to loose it.
Long live 250 g

"242g"
Brilliant! I'm really impressed. Whether it serves any practical purpose or not, you have a "bite me" sense of humor.

 

[Boatmans]

@quorneng those are some nice planes. But more importantly you are right about the body being a big source of weight.
I have been doing some wing area, drag, lift calcs and I think I need more wing area.
To lighten the load I am going to try and print the wing ribs and spars. And then put tape over them to act as the skin. And put a carbon rod through it for more strength. This should half the weight. I will post an update later.

Also I found a promising motor. Thoughts? Can anyone best the efficiency for that weight, is know if a better brand? https://sunnyskyusa.com/collections/x-v3-motors/products/sunnysky-x2302

 

[sprzout]

While it's not you BUILDING it, this will fit exactly what you want:

https://www.readymaderc.com/products/details/strix-nano-goblin-high-performance-fpv-plank-pnp

230g WITH battery; if you use the recommended 2S1P 3200mah Lithium Ion battery pack, you can fly it for approx. 25-30 min. I take it up and will put two 10 minute flights on it, then check the battery life and typically find I've got 40-50% of the battery life left if i'm not flying it hard. The guys at my field can't get over how long a flight I can get out of it, and how fast and responsive it is when i have it in the high rates.

in addition, you can set up FPV for it later if you decide to go that route; I've got an FPV setup for it but haven't actually gotten it hooked up yet (laziness on my part).

You might be able to build the FT Goblin to similar specs, but that's a larger plane and may not be in the sub-250g category you're looking for.

 

[Monte.C]

@quorneng...found a promising motor.

Hey I'm impressed. I can't completely juggle all the numbers - Kv, A, etc, but I'll take 2 please. That very low Kv figure means it'll spin a lot slower, right? Then larger props... It sounds more like what I think I'm trying to do right now with small floaty planes. Pretty soon I'll be running a very small & light plane on an 1106-4500 drone motor. I think I understand this'll spin much faster, and it's spec'd for a 3" prop. Anyone confirm or comment?

I do have plans to build a jet a little later down the line to run on twin 1106s & 3" props. It seems this 1106 setup is more suited to the little jet. I think.

 

[mastermalpass]

My only home-design to come in sub-250 kinda did so by accident. I generally wanted a lightweight plane so it can not only fly slowly but also dive slowly (high drag / inertia ratio, effectively flying with the airbrakes on the whole time).

It was powered by an 800mAh 3S and the weight was around 280g or so. So I bought it a 500mAh 2S and saw what that came down to... 253g

One the next iteration (plane in my profile pic) I used much less hot glue, opting for epoxy instead and also used a smaller ESC. Actively aiming for sub-250 like that brought the weight right down to around 220g when carrying the 2S. When being repeatedly crashed by the beginner I'm teaching, it was revealed that the tape was better at holding its weak points together than hot glue. The following two models that had the wing changed for a delta config, one of which includes a KF2 airfoil the other using the bigger ESC, have also come in sub-250 with the 2S. Using beads of hot glue mainly to help form the fuselage pieces while tape was the primary joining method to stick the fuselage pieces to the wing plate and to each other..

I will note however that these models are small - 500mm wing span and 500mm nose-to-tail.

 

[flyingkelpie]

That plane looks great! Could you make plans for it?

 

[mastermalpass]

That plane looks great! Could you make plans for it?

Cheers Flyingkelpie! The plans are coming. The reason this plane has been made so many times over is to perfect the plans for other people to use. The one pictured above is awaiting nice maiden weather for examination. Then, hopefully on Christmas day, my Dad will fly it and I can examine its beginner-friendliness. After that, I will make final adjustments to the plan. I did want to get more of the promotional material done before the release, but Mackiver's eager to try it out and I figured it would be silly to delay the release in favour of promoting it when I already have interested flyers on this site.

 

[flyingkelpie]

I'll need to try it once they come out! Just was working on building the tiny scout.

 

[mastermalpass]

I'll need to try it once they come out! Just was working on building the tiny scout.

You may be glad to know that the prototype and three of the iterations used all the parts from a crashed mini scout!

 

[flyingkelpie]

You may be glad to know that the prototype and three of the iterations used all the parts from a crashed mini scout!

Cool! Maybe once my mini scout DIES enough I can use it for one of those!

 

[Boatmans]

Thanks,this is all really helpful. I have decided on for going a 3D printed skin as it's just too heavy for this category of model

 

[Boatmans]

after a couple iterations is what I came up with. Essentially I have two models overlapping in cure. One model is the actual wing design which I set to have no skin so that it only prints the interior support structure. I set the support structure with an offset angle so that it lines up perfectly with the force axes on the wing. I.E. long Spurs and reinforcing ribs. Then there is a second model. This model is just the outer frame around the wing section. I essentially slice the wing four times and then stitch it back together in fusion 360. With this overlaid on the original and print both of them flat I am able to get be interior structure of the wing and then a solid outer frame. My original plan was just to cover this in packing tape. But though it is quite easy to do it's not very strong. I'm hoping I can dig up some of my old wing covering material and heat shrink that onto it. Should be quite strong and light. Overall I was able to get that wing section from 8 G with a 3D printed skin down to 4 G with the tape skin.

I finished printing out the entire wing section now I'm just modifying the original design to have a motor mount.

Despite my and other people's cautions about when warping period do the size of the plane looks like I'll only be able to mount the servos in the center of the body which means I'm going to have carbon fiber rods traveling the length of the wing and twisting at the ends. I have done torque measurements and it does appear to be within operational limits of the servo. I am currently unaware of the where this will have on the servos. And if the swing more will be controllable. If the wing were being does not work I will investigate traditional control services.

My current weight estimations allow me to have POV and ardu pilot hardware installed on the plane and still achieve my half hour flight time with the lithium ion batteries. My current restriction is that the lithium batteries weigh 100 g. Any smaller and they wouldn't have the current output necessary to drive the plane. If the looking batteries turn out to be too cumbersome I am investigating switching to a small 300 milliamp hour lipo 2s system. Hopefully the reduction in weight will recoup the losses in electrical capacity. All of the battery may need to be split apart in order to fit in the wing section.

Overall this scratch bultd is progressing quite nicely. I will post more updates as I progress on the plane. Most of the parts won't get here until February so might be a week or two before I have any updates.