Guys,

With all the new Super Awesome EPP Foam Blocks that we got in stock at Vortex-RC ( http://www.vortex-rc.com/product-category/building-materials/epp-foam-blocks-sheets-india/ ) , I wanted to build some Flying Wings that we could build, fly, and once tested put them up for on our site for everyone to enjoy,

Hopefully over the course of next few weeks, I shall update this thread on what all goes into the process of thinking, planning, prototyping, improving upon and finally bringing some planes to production to be made available on our website

EPP Foam is great because :
A. Its strong yet flexible. So it doesn't shatter and break easily. Can make very resilient planes that can take a beating
B. Its pretty light, and cuts with a Hot wire very neatly.
C. Its CA Friendly ! Yes ! Makes the builds very fast and light.

My Idea is to build 3 or 4 sizes of wings :

A. Micro Size : ~ 600mm Wingspan
Probably Under 250gm weight     yeah , clear from all the DGCA hassle, For fun flying , light and small , maybe do some FPV too. I haven't yet built such a small model yet but pretty inclined to do so now ! This would probably take one of those small Drone racer motors and use ~ 700-1000mah Lipo.

B. Standard Size: ~ 1000mm Wingspan
This would be probably be the "standard" RC plane that will probably take the  28XX Motor, 2200mah Lipo and some FPV gear.

C. Large Size : ~ 1400-1500mm Wingspan .
For long endurance FPV, Aerial Photomapping, lots of space for RC electronics, cameras, autopilots, pizzas, and all .

Have always hated to import these planes from abroad. Exorbitant shipping fee, Customs hassles and all. Would be awesome to get these planes right here in India. Plus going to be so much fun in designing and building these wings !

Here's whats I am thinking :



Step 1 : Designing.
Though I have an extensive experience of designing and building Flying wings, whenever scratchbuilding, I start off with drawing the panels, and usually cross reference against one of the proven planes. In this case, I checked my layouts against:
– Vortex-RC Speedster and Speedster Pro ( our very own models  which are super to fly)
- Ritewing Zephyr 2 and Zephyr 3 ( which I happen own and have extensively flown ) ,
– Ritewing Drak and its Mini ( Got killer looks and seems like the best option for Long endurance aerial Photomapping )
– Multiplex Funjet ( An extremely fast, small and fun plane to fly )

Wouldn't it be awesome to get something similar Made, right here in India ! Super exciting.

The more I look, the more I am tempted to experiment, build and test fly all of these.
Of course when designing I have to also take in consideration that i have 50MM blocks, and I need to optimise for, and also their size 1000x1200mm to avoid any wastage when we go into production.

For a flying wing, there are 4 Very important Parameters :
1. Wingspan .
2. Root Chord.
3. Tip Chord.
4. Sweep


All of these affect the characteristics of the plane . 

Will continue more with pictures and updates.

  to Gaurav.

Though there are several factors that are important in the design of a Flying wing, the #1 most important thing to get it right is :
Center of Gravity (CG)

Flying wings are very touchy with CG.They usually offer very tight acceptable tolerances, and fly very poorly, if the CG is even a few MM outside the recommended position. A great tool to calculate the starting point of the CG is : http://fwcg.3dzone.dk/
This tool takes in the Wingspan/Root Chord/Tip Chord and the sweep and gives a good approximation of where the CG should be.

The airfoil is the other important aspect. Though in my opinion a bit over hyped. On many forums, people have gone at length to state that you need a reflexed airfoil for a flying wing to fly properly. The problem with reflexed airfoils, is that usually they are too thin, specially at the trailing edge, and though it may be possible to make models from balsa accurately, the same is not really possible with foam. Plus with swept wing airplanes you do not need the reflexed airfoils, you can probably do with any airfoil, just a little up Elevator gives the necessary reflex.

I am going to continue my flying wing design thoughts and experiments at my blog :
http://www.vortex-rc.com/2017/11/21/designing-building-epp-flying-wings/

and more frequent updates ( photos and videos ) are being posted on my Facebook page :
https://www.facebook.com/VortexRC/

Its just very convenient to share media there directly from the phone, than to being it here on the forum.

Just did few test planes :

1. 600MM Micro FPV plane.


http://www.vortex-rc.com/2017/11/22/600mm-epp-flying-wing/

Built this and ended up tail heavy. Had to move the battery too far forward to balance, Gave up and added a blunt edge that protruded ahead of the nose.  Dont like that sticking out, so probably will be increasing the sweep to get the CG a bit behind, and also getting the motor a few MM forward, I can use a lighter motor, but prefer to use the quad racer motors which are pretty popular these days.  AUW of this plane is coming to less than 200Gms, which is cool.

My next attempt at this would be change the design slightly so as to get the CG without the blunt edge sticking out from the nose.
I did some FPV on this with a the 3-in-1 All in one camera. .Seems to be a fun plane. Very light. Very small , and a good deal of fun.
The EPP material just makes it too cool.

2. Been playing around with the 1200mm size design.

Designing this around 3700mah 4S or 5000mah 3S Lipo, fully enclosed/covered battery and electronics bay, with enough space inside to put all the electronics including autopilot ( Pixhawk / inav etc etc  ) , Forward Live view FPV cam and HD Cam, and also have space for a downward facing Camera for aerial photomapping.

Check out the intro here :


And the maiden here :


The maiden was super. Had gone in with a light setup. Used a smaller 2200mah 4S lipo, and no autopilot etc.
Next step would be to start adding in the gear and take it up one step at a time.

3. Also a 36 inch FPVWRA FPV Wing Racing Association Spec Flying wing.  
This is per the standard spec, that meets the FPV Wing racing guidelines.



Flew superbly, did the maiden today, infact went on FPV right after launch on the maiden itself.
Tracked as if on rails, and extremely smooth and very very fast. Just loved it.

EPP material makes it very strong and light, and i would say this is one of the most fun and exciting FPV plane i have flown. Very fast, very smooth, and just brilliant..

I have several gigabytes of videos and pictures, trying to sort them all out so i can organise and post them here.

Really Really eager to bring out share these planes with all of you guys.

Before i can offer the kits on my website, there are certain things that i need to do :
1. Stock up on the CF spars.. Need the strips for the reinforcement

2. Find out on a good source for Balsa aileron stock . I am using the EPP ailerons/elevons now, but want to offer Balsa elevons as an upgrade. From what i have searched around i haven't found a good supplier yet. Maybe someone can help me here.

Lots of things still to do. But very excited !
Will update here as we move on with this project.

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to stay updated...

Loved the video. It's so stable. Anyone can fly this easily.

A bit more on the FPVWRA Racing Wing



Got bits of some DVR live footage in here, waiting to get a Mobius, so we can get the action in HD.

I am thinking of offering this as-is with an option of a blunt edge. The Blunt edge would be against the racing spec, but would offer space to add in HD camera and more fancy electronics like OSD and all .

Also we are not yet laminating our EPP yet. We have a bunch of laminates , I am reviewing which one works best for EPP and can give that in the kit too.

When laminated the EPP wings would be extremely durable..

Update on the Micro FPV Flying wing 600mm wingspan.

Getting this one right was probably the hardest, because got very tight tolerance on the CG, and with small size there was little room for moving the equipment around.  Selection of airfoil was also an issue as for this size becomes thin quite fast.

The first plane we made came out too heavy. I thought ill get it flying with a 3S Lipo, but after building and flying that one figured that 2S would be enough. That one weighed 300gms. 

Then made another one on a thinner airfoil. This came in slightly tail heavy, To get the CG right, had to put in a blunt nose that extended forward past the panels. I sort of didnt like the nose jutting out in front, made it vulnerable to break . Had also used a thin reflexed airfoil (Peter Wick PW-75 )  on this one. 

In the 3rd version, that we completed just yesterday, I got in a bit more sweep to push the CG back, tweaked the airfoil so i can get the thickness and yet the reflex, and finally got the CG in right place !! The AUW of this comes to 211 gms. Thats with the 2S 1000mah Lipo and the micro FPV gear.



I used 9Gm TowerPro SG90 servos. I could have saved 10 gms more had i used 5Gm servos, which would have been enough, but i didnt have 'em.
Also, i used the Quad racer Emax motor. This seems to be slightly on the heavier side. Could have saved 10 more gms using a lighter ~12gm motor. ( again didnt have one to try ) .

So far quite happy. Flew very well. Shall upload a video shortly.
Its so small, portable, and doesn't need a lot of space to fly, and awesome to fly.

Getting the Pixhawk into the 1200mm Mapping wing.
Got ample amount of space inside. Enough to fit in a Downward facing GoPro as well.

The EPP Elevons are holding well so far. However, with all the gear and cameras i would prefer having balsa elevons.
Since I am having a hard time getting these elevons here in India, I may opt for built-up elevons.

They would be lighter, though will need some build amount of building, and might be a great option. Will have to build one to try.

Meanwhile, Using XFLR5 to simulate and test the airfoils, and also tweak the sweep, root chord, tip chord and the placement of equipment.

Getting the CG spot on is the most crucial thing. Its tough to design a flying wing that can work with a variety of batteries, cameras, and gear !

Designing a decent performing Flying wing is no easy task. Selection of the right airfoil amidst thousands available, the right sweep, and taper, getting the right CG, with the correct amount of washout , needless to say the winglet design, shape  with each in itself a subject of research.

As with any chevron styled ( swept back ) flying wing, its easy to induce tip stalls, specially as the wing loading goes up.  The chinese FPV planes are notorious at doing that . They stalls sting like a bee putting the planes in a tailspin, hard to recover from ( because of the lack of a tail ) .

Getting all of the parameters correct is a work of research with endless prototyping and trials.

I am  trying to get the wing loading in the range of 13 oz/sq-ft. Right now facing some tip stalls with our new design, optimising the foils a bit and on with our fourth prototype. Failures don't disappoint, they will teach ways on how not to do things.