The Gull Wing platform: Design and variants

[GreenAce92]

Gull Wing Flying Wing
Beauty in Natural Design
[Have to be honest this blog fell apart after moving images on Photobucket]

My "ideal gull wing"






Model failed to fly despite a nice take off


View this video on YouTube




Brief summary of tested models and variation

View this video on YouTube






Structural testing


View this video on YouTube


Crashed models being found
GT-15

View this video on YouTube

GT-14

View this video on YouTube

Crashing

View this video on YouTube

[GreenAce92]

OK yes, lots of reading, I apologize.

The next model is tough because I have to find aluminum paste / zinc solder and zinc flux in order to solder 6 cells in 6 different locations together to form a 4400 mAh pack.

So if anyone is interested in this model, it would either be a kit (foam only, outline of where parts go) or a built and sealed model (as in everything works, all you have to do is install fpv gear).

I will upload my other videos and such (primarily for my purposes) at a later date but the last model will be all FPV and aerial surveying. I will get probably one close up of the air frame but that'll be it.

I flew the farthest and highest with the GT-06 model and it wasn't even fiber glassed! Plus it was weak as hell too.

I achieved my dream of flying over a breaker wall approximately 0.7miles out, yes not far but my fpv radio gear sucks. (I focus on the plane you see?)
But the thrill of flying over fishermen and skimming that breaker wall was phenomenal. It has long flight times too but I kept flying on full throttle for the most part.

Unfortunately I did not get the wonderful fpv footage (the lake was a mirror, ending credits of the film above) the dvr had died so all I got was a message "file failed" where the recorded footage was supposed to be.

[GreenAce92]

Polyhedral Gull Wing

One of the things I tried with the 07 was to cut slits into the outer panels and add some polyhedral.

Despite thinking that it would make the plane more stable somehow, the aircraft actually became worse. Not sure if this was because the elevon which was now going in two directions was still moving as one piece or if the addition of another dihedral source is just a bad idea.


This is the difference between the standard design and the polyhedral model.

Standard



Polyhedral





Perhaps if I had trimmed the elevons to the point where the outer wing tip dihedral began, maybe that would have worked.

[Vitamin J]

Sweet man, I like the flaps. And nice job flying out over 1km. Was that FPV footage recorded on the ground or onboard the plane? It was really clean, nice job!

[GreenAce92]

Yeah that was recorded from the ground, using the DVR from you.

Yeah man it was great to finally start flying fpv again, I just work on the plane a lot that's my thing.

Anyway, I know that the film you see does not support my documentation, I just really got screwed over by superficial friendship.

Anyway, it is a fantastic intermediate and above plane. I'll have more in two weeks.

GT-07 is stiff and sleek as hell. But it is also broken so on to the second to final model.

[GreenAce92]

You know what FPV misses? Real thrill... I mean sure you get scared that you are flying something that you can't see anymore by your naked eye but... There is no risk...

Financially or legally maybe but I think FPV will never be like the real thing, unless you can miniturize yourself.

[GreenAce92]

GT-01 [S] Blended center panel extension variant

View this video on YouTube

Construction of GT-01 [S]

[ compilation video goes here ]

Bloopers


View this video on YouTube

Flights


View this video on YouTube

Personal Notes

The GT-01 [S] had problems in two areas: Vibration and Stability.

I have witnessed this air frame drift in front of my eyes [ video ] and that is not good.

I think that this was a result of the odd mounting of what would be the central panels on a standard gull wing model which where then mounted to the extended / blended center section.


This may not have achieved the correct angle. I did note in the past that adding a large body to the central panels of the GT-01 would disrupt airflow over the central panels and as a result violent loss of stability / abrupt aerial front flips.

The vibration was another problem and this was because of the weak structure. Also it was because of the odd airfoils, I didn't study the flow of air over them or anything so when I made this cambered center section, it was a bad idea.

At first I thought increasing the center panel solved the problem of vibrations but really all it was doing was slowing down the air frame thus preventing it from gaining speed and then vibrating to pieces.

The GT-01 [S] is technically GT-05.

I decided to put the project on hold so that I could pursue a more faster / smaller model.

Also I noted that the outer wing tip controls acted more like air brakes rather than ailerons banking the aircraft. It is evident in the video above that the model does have turning problems.

I would imagine that improving the control system to what the GT-06 has would help the GT-01 [S] become a better platform.

Ideally I would design this to carry a big AVCHD camcorder. Sort of like a flying eye.

<<< Landed in Atlanta Georgia. Hello Sentry!!!! >>> Posted from a window out looking some terminals

[GreenAce92]

GT-06 built from left overs of GT-01 [S]

View this video on YouTube

The GT-06 used a BP Hobbies 1500kv brushless motor powered by a shorted 2200mAh pack.
By shorted I mean I had accidentally touched the ends together when the battery was at full charge



The GT-07 airframe weighed 23oz and had a wingloading of about 12oz / sq ft. So it wasn't a heavy plane really.

The model even used a tiny trimmed GWS DD 8x4 propeller (trimmed to about 6x4)

It had very little power, so the flaps definitely helped on take off and if you watch, the plane climbs away like a real plane with flaps down for take off.

FPV flying

[ fpv only video here ]

The air frame was aerodynamically stable. No yaw or any unwanted "conditions". The GT-06 was longitudinally stable and was a joy to fly.

Flight time was 20mins with the bad 2200mAh pack powering both video system and the aircraft itself.

The barrel rolls were quick and crisp. Take offs were linear and landing approaches were predictable.



GT-06 Flying over the lake
Funny conversation with a stranger


View this video on YouTube

[GreenAce92]

GT-07 Hotliner

This model was a step up from the GT-06

Using what I learned from the 06, primarily the new control system, I went ahead and decided to build a faster, stronger and more impressive model.

Shoulder mounting

Aside from being fiber glassed, the main difference was the central joint.The 07 now used a shoulder mount central joint system which meant a definite platform attached to the model, not just hot glued to the surface of the central panels.

Power plant upgrade

The 07 used an AXI 2808/16 motor which when paired with a 6x6 propeller is considered a hotliner. With a pitch speed of ~115 mph, the AXI is a perfect match for this new robust airframe.

I also bought a new 3S battery, a Venom pack which had a constant C rating of 50 and a maximum of 100!!

So now I was able to push the model up to 60 even 70mph (I admit it is slow) but this was only 3 cells.

Flaps and multiple flight modes

The nice thing about the 06 and 07 was the new control system. With the 07 being heavier and faster, the flaps were very nice.

It felt like flying two models when switching between no camber (slight reflex) to landing mode (80% deflection).

The model did not have any problems turning when the flaps were down as long as you kept power constant. Perhaps a little pulsing was required for turning but overall it was like flying a bullet, then a butterfly. Not to be taken literally but landings and takeoffs were smooth and linear.

Problems noted in flight

One thing I noticed was since the model did not have over 1:1 thrust to weight, when approaching the point of fail "can't climb anymore" the model started to lose stability (yaw).

The 07 had a construction flaw, one of the joints was not correct, therefore the stability was unlike that of the 06, which flew rock solid, no yaw what so ever despite the fact that the 06 flew on a slow 1500kv BP Hobbies motor.

So I had this model which was fast and eager to roll, not a pleasant airplane to fly. The roll rates were insane! I had to dial it down to 75% DR for easy rolls but not uncontrollable. When properly built, these airplanes become more stable the faster they fly.

Another problem I noted was the weak new joints that I made! They were weak because of the material I used. I picked up these 5 gallon paint sticks from Home Depot and while they are nicely cut to 1/4 of an inch, they are very weak when having a small surface area.

So when approaching 70mph (light dive), the model would start to vibrate and at one point even failed! The wooden central spar snapped.

The end of GT-07

The first crash was a product of a bad decision on my part.

I once broke my trainer switch on my Hitec Eclipse 7 (I dropped it down a flight of stairs). So I replaced the switch with a standard switch (non-spring loaded)

So as I was flying my beautiful shiny GT-07 which even had my signature twin stripes on the right wing, I decided to bring it in for a landing.

On my approach I started a shallow bank at about 10' off the ground, I was going to power up and come around again, however instead of applying the flaps, I instead flip the trainer switch.

Full power, left bank and no control. I watched my model smash into the ground.

Not bad I think to myself. I fix it up only to find that one of the four central gull joints broke (paint stick). Damn.

I then put it back together this time without the shoulder mounting. I decided to mount it classic style like the GT-06.

This time I had problems with the angles of the wings, thrust angle of the motor and also structural weakness from the first crash.

[Insert fail launch video here]

I didn't have any tools / materials to fix this airplane. I was at my friends house who does not fly model airplanes. So I was forced to borrow his mother's glue gun for her "crafts" and also use some bread ties to put the gull wing together.

This was not turning out so well. Then I found some duct tape! Ahh good old duct tape.

Now I had the 07 flying again. This time with another 2200mAh pack on board (embedded in the wings) which didn't help at all as I couldn't solder the aluminum tabs.

Despite being heavier the plane flew well although being way faster and requiring a longer takeoff run (no running on my part).

Basically I just gutted the plane, the outer panels are in great condition, it is the central left panel which took the crash.

[Vitamin J]

Man that puller version was sweet! It just flew out of your hands so gracefully.