I'm new to RC. Looking about the web brought up a question
perhaps someone more knowledgeable can answer. What would
happen if you built a flying wing with a small amount of
dihedral? Would it be more forgiving for beginners?
Wouldn't inverted flight be unstable? TIA.
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.
| 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
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
Most will fly inverted, but performance tends to be significantly
| 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.
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
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.
| 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
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, but that's not what I said ...
`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
| Doug, again what is that zagi copy that you like with the X in the name?
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.
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.)
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.
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
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.
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