Flying wing design

Most flying wing designs are surprisingly stable and relatively easy to fly one an RC pilot has mastered his basic trainer aircraft. Electric flying wings like the Great Planes Slinger/ Mini Slinger, the Thunder Tiger Velocity EP, or the Parkzone Stryker are very popular as second aircraft because they look cool, can fly fast, and aren't too difficult to control so long as one remembers to turn down the throttle once in a while.

The Zagi family of aircraft from Trick R/C is another very popular family of flying wing. Some models like the Tazz w/ brushless outrunner motor can be very high performance, however, and are better as a "next step up" after a pilot has flown something more tame and wants another challenge. Several of the "brushed" motor Zagis are available that are good choices for the budding pilot, however, and the EPP wing cores used in the Zagi models have a reputation for being very hard to damage.

Part of what makes these planes easy to fly is the lack of dihedral. They fly as well upside down as they do right side up. Spinning them around quickly and getting comfortable with inverted flight help newer pilots acclimate to faster manuevers that will be commmonplace as they learn to fly scale IMAC aerobatic planes and/or 3D models.

If you've mastered your basic 4-channel aileron trainer and you want to move up to something faster that looks cool but is still easy to fly, one of these electric flying wings is a terrific choice.

Ed P. a.k.a. bigedmustafa

| Most flying wing designs are surprisingly stable and relatively easy | to fly

I'm going to have to disagree with you.

I've flown several, powered and unpowered, from various manufacturers.

They generally are not stable and have significant bad habits (such as a tendancy to tip stall.) They're also very sensitive to the correct CoG location -- off by a fraction of an inch and you can go from a plane that can barely keep it's nose up to one that's almost unflyable.

However, they're generally resiliant, and that is what makes it work

-- you can crash them repeatedly and they'll probably survive.

I'm not saying they're bad, but they're generally not so easy to fly. There are some exceptions, but for the most part they're hard to fly.

| Part of what makes these planes easy to fly is the lack of dihedral. They | fly as well upside down as they do right side up.

Only if they have a symmetrical airfoil, which most do not, and the CoG is set just right so the elevons aren't going up to keep the nose up.

Most will fly inverted, but performance tends to be significantly degraded.

| If you've mastered your basic 4-channel aileron trainer and you want to move | up to something faster that looks cool but is still easy to fly, one of | these electric flying wings is a terrific choice.

And while I disagree with most of this post, this part I agree with.

That Stryker 27C, the brushless one, hauls serious ass. It really requires that somebody stay on top of it, but it flies really well, especially for a RTF.

Doug is talking about EPP foam wings here. There are balsa built up flying wings that don't crash as well. :).

Doug, again what is that zagi copy that you like with the X in the name? mk

The three that I mentioned initially - the GP Slinger/Mini Slinger, the TT Velocity, and the F-27 Stryker - are ARFs with very specific battery compartments designed to make balancing on the CG almost automatic if you use the recommended battery pack that the plane was designed for.

The Zagi XT, the only one I've personally gotten to see close up for any period of time, also had a similar compartment and was bundled with a NiMH flight pack for near-foolproof balancing so long as the instructions were followed.

I have no doubt there are plenty of poorly designed flying wings available, just as I'm sure that even a good flying wing without such exacting design for battery weight and placement would be challenging for a novice to balance and trim correctly.

With regard to the GP Slinger in particular however, I've seen pilots who could barely fly their glow trainers by themselves have no problem flying the Slinger around and actually look good while doing it. Sure, they can be tip stalled or put into the flying wing "death spiral," but these planes do generally bounce pretty well.

I can only relay what I've seen, and I've seen several pilots who weren't particularly proficient with other aircraft fly Slingers and Strykers like they were expert pilots.

Ed P

| The three that I mentioned initially - the GP Slinger/Mini Slinger, the TT | Velocity, and the F-27 Stryker

I have a Slinger (along with my 10 or so other various flying wings)

-- it does not come with a battery, and the battery compartment is large enough to let you move the battery around a lot.

(It's also made with really crappy foam, I might add -- not very stiff, and even adding bunches of CF wouldn't fix mine adequately.)

| The Zagi XT, the only one I've personally gotten to see close up for any | period of time, also had a similar compartment and was bundled with a NiMH | flight pack for near-foolproof balancing so long as the instructions were | followed.

With that cavaet (all instructions were followed), all the flying wings will be perfectly balanced all the time!

| I have no doubt there are plenty of poorly designed flying wings available

They're not `poorly designed', they just require that you follow the instructions and be careful about the CoG, and you put the battery in the right place every time, because the margin for error is much smaller than with typical planes.

| With regard to the GP Slinger in particular however, I've seen pilots who | could barely fly their glow trainers by themselves have no problem flying | the Slinger around and actually look good while doing it. Sure, they can be | tip stalled or put into the flying wing "death spiral,"

They're prone to it, and have no banking stability. This makes them, all else being equal, harder to fly than planes with dihedral and your typical `plane' shape. And since the CoG is so much more critical, it's that much more likely that sombody will get it wrong (even with an RTF, after a few repairs, modifications or battery changes.)

| but these planes do generally bounce pretty well.

Yes, but I was pointing out that they're harder to fly. Not impossible, but harder.

| I can only relay what I've seen, and I've seen several pilots who weren't | particularly proficient with other aircraft fly Slingers and Strykers like | they were expert pilots.

Then they were better pilots than you gave them credit for. In any event, people can and do learn to fly on planes that are hard to fly.

OK Doug, I will recommend that folks avoid these finicky death-spiraling disasters henceforth. Thank you for showing me the error of my ways.

| OK Doug, I will recommend that folks avoid these f `Do we still carry those flying wings?' `You mean the widow makers?'

I've had alot of experience with rc flying wings, so maybe some of this info can help you. I have a foam covered with balsa swept wing called a Javelin, it has a symetrical airfoil and no wash-out ( wing twist). It is very fast but has a terrible tip stall and really no low speed handling at all. Swept wings of this type depend on a slight reflex at the rear of the airfoil for stablity, this creates a slight down-force at the back sort of like a tail. It helps, but doesn't seem to get the job done by itself. I also have a couple of Klingberg wings which are actually models based on the Horten 3 sailplane. They use an actual Horten airfoil with several degrees of wash-out. I've never measured the wash-out but it is probably about 6 degrees. These planes fly great both slow and fast, but there is a noticable drag penalty for having the washout. Most full size swept flying wings used the wash-out method: Northrop used a symetrical airfoil and 4 degrees wash-out. The Hortens always used semi-symetrical and and at least that much wash-out. I recently built a scale model of the Horten 229 v1 using all the best plan data ( A.L. Bentley) and it flys best of any I've built. This one uses semi-symerical with some reflex toward the root, transitioning to symetrical at the tip. This minimizes the amount of twist needed, which was 4 degrees. It is also true that Flying Wings are sensitive to C.G. location. It should be forward of 25% of the Mean Aerodynamic Chord. Basically, start nose-heavy.

| Doug, again what is that zagi copy that you like with the X in the name?

XE2 probably.

Though there's really a ton of clones out there and most of them are pretty similar. Zagi may have really made these sorts of planes popular, but then other vendors started putting out stuff that was significantly better than what Zagi was doing. I haven't really kept up with them in the past few years so I don't know if Zagi has caught up, but upon looking at their current offerings, I'm guessing not.

Things that make these sorts of planes better --

-- good airfoil (alas, `good' depends a lot on how the plane is meant to fly, but in general flat bottom airfoils are not very good.) -- stiff, light foam -- foam that is CA and goop safe. ( See

for an example of what can happen. ) -- CF spars as needed to stiffen things -- no canopy, things buried in the wing -- cooling for the battery and motor if there is one -- padding in front of any electronics or battery to protect it in an accident. Also, it's nice to put the battery in front of the RX rather than in back, so it doesn't crush the RX in a crash. -- pushrods buried in the wing rather than exposed. -- covered with ultracote rather than packing tape Some of these have to be done by the manufacturer of the kit, and some can be done by the end user.

| I have a foam covered with balsa swept wing called a Javelin, it has a | symetrical airfoil and no wash-out ( wing twist). It is very fast but | has a terrible tip stall and really no low speed handling at all.

Good point, I forgot about that ...

Flying wings do tend to have wash-out to help reduce the tendency to tip stall. The problem with that is that in inverted flight, wash-out becomes wash-in, and so the plane becomes even more prone to tip stall.

In general, most flying wings fly inverted poorly (though from what Daniel described, his Javelin should fly as well inverted as right side up, thanks to no washout and the symmetrical airfoil -- but this sort of setup is rather rare.)

"Daniel Krier" wrote

For the Gremlin RC Combat wing, I seem to recall the CG is something more like

15% to 17%. 25% would be at the most rearward range of CG, I would think.

I'm part of a small team of ME university students that just finished competing in a DBF competition with a flying wing. The wing we used in competiton was our first prototype. Due to the design requirement of a fairly large payload bay, it ended up being a tractor with 20 degrees sweep, reflexed and 4 degrees washout. Had the CG set for 10% in front of the AC. It flew very well, very stable. Handled 45 degree turns with ease, even in very windy conditions. Looked way cool too. There were many that said our design would not work and tried to scare us into thinking we were going to have our hands full, but they couldn't have been further from the truth. Not sure if its because we performed good design analysis or were very lucky. It was a fantastic experience. Robert

On Thu, 17 Apr 2008 16:13:08 -0700, Robert Dorsey wrote in :

Congratulations!

Have you got a website about your team & design?

An article about the competiton?

Marty

Hi sound interesting can send some pictures so ee'll all enjoy??

Hi Marty, I have some static pictures with me. I'm supposed to get the flying video this monday from my teammate. Where is a good place to put them? We currently don't have them on a website, but may do that in the near future to share our experience with future teams. It was the SAE West Aero Design competiton. Teamrcpilot.com is supposed to be puting some pictures up on their website soon.

Both of us are pilots, but never flown RC (yet). I have built a couple of full size planes, and the feeling one gets from flying in an airplane you built is really close to the feeling you get seeing your design take flight the first try. I think the biggest compliment we recieved was from the gentleman that flew it for us. He has 22 years of RC experience and said if flew great and wouldn't mind adding it to his collection.

:

On Fri, 18 Apr 2008 16:50:36 -0700, Robert Dorsey wrote in :

Picasa is great for photos.

You Tube for videos.

Great!

Well done!

Thanks for sharing the story with us.

Looking forward to seeing the photos & vids ...

Marty

I bought a Goldberg Tiger 2 ARF that another guy build and never flew, and I'm now going over it to get it ready to fly. There is still a lot to do, but I ran into something I haven't seen before. The control rod for the throttle arm comes out of the firewall high on the left side of the airplane which is directly opposite the location of most throttle arm assemblies. Its obvious that the guy had a motor mounted on the airplane at one time, and I'm wondering if any motors are produced and shipped with the carb assembly having the throttle arm on the right side. Or is there something else I'm not thinking of? It could not be that an engine was initially mounted in the inverted position. The engine compartment would not accommodate this.

Can anyone clarify for this neophyte.

Harlan

Some four strokes have the throttle arm on the other side.

Also, most engines allow the carb to be installed both ways. The fuel nipple would point in the wrong direction, but it would probably still work. On some engines (Super Tigre) you can even adjust the fuel nipple. Maybe he flipped the carb to get the servo installation easier, or maybe he just installed the carb incorrectly?

On Sat, 19 Apr 2008 12:44:29 +0200, Robert Roland wrote in :

I like that theory a lot.

I like your analysis here, too.

It **seems** to me that I almost half misremember playing with reversing carbs on one engine or another once upon a time. I don't remember having success with it. Some carbs are definitely one-way only, I think--I think I remember them being notched to make room for a drawbar that holds them in place.

Others look as if they could easily be rotated, because there is no machining on the part that seats in the crankcase.

On the whole, H, my recommendation would be to relocate the throttle servo and the pushrod to suit your engine the way it comes from the factory. If you do decide to play with the carb, make sure that you reseat it well so that no air gets drawn into it around the seal between it and the crankcase. The same goes for tinkering with the needle-valve and fuel nipple. We can do a lot of damage to our engines by running them lean, and one way to do that is to allow air leaks.

Good luck with your project. Let us know what you learn!

Marty