aaindthu

Hi !

I have started building a flying wing design. It has 2 meter span and a pusher propeller. The wing is made of High density foam of 2 centimeter thickness.

I made the airfoil myself - the shape of which is shown in the picture below.


Here is the picture of the wing itself


Here is the motor mount.


Hopefully, this time I will have success.

Panther

Good luck mate. I think I have about 12 or 15 wings. Lost count....

It would be interesting to know the span and motor size etc.

aaindthu

12 or 15 wings? THAT'S A LOT OF WINGS!! I am building my first.

It has 2 meter wing span and the motor size is 2212 - 1400 kv and 8 inch prop.

I just glued in the motor to the wings and made rooms for the battery, ESC and the receiver.

solentlife

I would suggest you balance not only forward - back but also across the span.

My Wings - I glue a U clip into the CoG point on centre line. I can then hang the wing and balance her in all directions.

Easiest way to balance spanwise is to push in nails to the wing tip ..

Nigel

aaindthu

This is a very valuable info, something which I was going to neglect, because I have seen (in Youtube) many FPV flying wings with camera Transmitter mounted on one side of the wing and nobody explains about balancing the wing spanwise.

Thank you for bringing it up.

solentlife

Its actually worthwhile on ALL planes especially those you want to aerobat or perform clean manoeuvres ... but very important for flying wings ... they have very little physical side to compensate ...

Its also worth having side force generator plates at wing ends ... (vertical fins) ... to help steady the wing.

Nigel

aaindthu

Thank you. I will be adding winglets / vertical fins finally.

soarrich

Looks good! Good luck.

quorneng

aaindthu
That is impressive bit of work!
Have you flown it yet?
Be aware that such a flying wing is much more sensitive to the CofG position than a conventional plane that has it 'stabilising' tail surface a relatively a long way back.
With a flying wing its longitudinal stability has to be created by the wing itself.

Your wing section with its raised trailing edge will help and the modest sweep back will make things just a little less sensitive.

Do let us know how you get on.

aaindthu

Thank you

aaindthu

Quorneng,

I did chuck the wing to see how it glides. It was fluttering couple of times. But after correcting the CoG, it flies pretty good. My wings are also flexing a little and that could have also caused the flutter. So I am going to add more sticks and make it very stiff from tip to tip. Probably that will solve the problem. Thank you. Will keep you posted on my progress.

solentlife

Flutter - that is typical of poorly balanced wing. As Q said- CoG on a wing is critical as it has no long moments to it. Its why the combat and extreme guys like them.

I would be inclined to not add more rods ... at some point it just adds weight instead of improving ...

Fly it without being extreme - see what it does - THEN decide if you want to add more 'sticks' ...

Dare I risk saying ? You seem to be moving quickly on from the initial trainer to more demanding flyers ? Do you intend to learn to fly more with the trainer or is that now in the past ?


Nigel

aaindthu

Nigel,

I think combat wings have very short wingspan whereas my wings are 2meters long.
And I agree that combat wings are very demanding as they seem to be flying very fast. I want my wings to fly slow like that 'Opterra' flying wing.

I love my trainer plane. I am Glad that you asked. But it's difficult to carry it out to the field. I never felt that I would need a car but now I wish I had one. But flying wing design is a lot easier to carry and a better airframe for FPV flying!!! Yes I am thinking about converting my wings into an FPV platform after some time. Too ambitious perhaps?? For a beginner??

solentlife

They say that moving forward and developing is based on having a goal that is more than present capability ...

You are most likely learning more about design and how these things work than most who fly for years 'ARF out of the box' ...

If your wing is designed to be a slow flyer - then that means even more so - do not add weight.

Ok - this model is not 2m ... but is just under 1m ...



There are no wood or CF spars in that at all. The flying wires are cosmetic as are the interplane struts. The wings have 6mm square FOAM spars running spanwise to create a curved top surface. Bottom of wing is 6mm and top 3mm Depron.



That model has flown into the deck ... hit a rock ! ... ploughed into snow and farm field ... and still survived. If I open the throttle - I can see the wings flex ... but fly her slow as she should ... she's a floating dream.

Nigel

aaindthu

That's one cool looking SE.5.a !! That's definitely on my list of planes that I'd love to build and fly (someday). Thank you for the tip. I will come up with some alternative to these 'sticks'.

quorneng

As Solentlife says for slow gentle flight much of the required light weight comes down to using the construction materials effectively to give the greatest strength for the lightest weight.
Obviously a working knowledge of structural design helps but much comes down to the intelligent use of simple trial and error!

This is my most recent "all foam" scale creation the Handley Page HP 115.

The original was built in 1961 to test the low speed performance of a very slender delta.
So an EDF with a span of 0.75 m and 1.75m long. It is made entirely (no reinforcing of any type anywhere) using Depron foam sheet that is just 2mm thick.

Do all designs work every time? Of course not! but as long as you learn from the failures then it is all valuable experience.

Just keep experimenting!

aaindthu

WOW!!! I can't believe my eyes. It looks like factory made.

Thanks for the tips I will keep the weight of my wings down.

Stick Dude

If you wish to rattle can paint it, I saw a cool method for use. Try Modge-podge foam covering liquid, it can be found at a local hobby or ebay. You can actually spray paint after the modge podge dries. Use a styro cup before you use it on your airplane though....

aaindthu

My flying wing did not fly as expected.

It was too heavy (650 grams) and it was too thin. (Just 2cm)

So, I am building a second one with three layers of the same foam sheet and I am going to cut it using hot wire technique.

The thickness of the wings will gradually reduce from the root to the tip.

Here are the three airfoil shapes that I am going to use it as "stencil" for my second flying wing.

This wing is going to be strong and should not require any additional reinforcement (saves a lot of weight) as it has 3 times the thickness.

aaindthu

Stick Dude,

Hi, I just checked if Modge-podge is available in India and it is available !!

It looks great. I will definitely check that out. Thanks a lot!!!

aaindthu

Cut the core wings and glued them together with epoxy

quorneng

aaindthu
That looks good.
I suspect the epoxy will be much stronger than the foam it is stuck to.
If you are concerned at the wing's strength this is a simple load test.
With the motor, battery and ESC (the heavy bits) placed on the wing at its centre can you then lift the wing up with your hands under each tip?
Not exactly scientific but it does impart a bending load at the wing root equivalent to pulling 4g or put another way it will be strong enough to safely do a loop!

aaindthu

Quorneng,

The wings are pretty strong with all the batteries and motor. Only the wing-tips flex a little when shaken.

In order to avoid tail heaviness, I have mounted the motor very forward - closer to the nose, with the propeller spinning through the wing like shown in the pictures.


I have connected the ESC, battery and propeller and checked it for any voilent vibrations while the prop rotates. I gave it upto 80% throttle and it was fine. Just the thrust was reduced a little, that's all.

Here is the picture of the whole wing.

aaindthu

Update on my flying wing :- Thrust is reduced a lot. Only at 40-50% throttle, I am feeling the thrust against my hand and a lot of noise

Should I be concerned ??

quorneng

'Slot in wing' props are less efficient but I would not expect as much as 50%. It is just a feeling or have you actually measured it?
it will make much more noise. After all such a layout is the basis of a siren!

There could be an advantage in having the motor in the wing rather than a bit above as the thrust will be exactly in line with the wing drag and will not alter the trim of the plane.

All you can do is try it and see!