How do I prevent death spirals?

[Craig Mckinley]

I have been flying my first wing for about 4 months and I love it. My Elle Bee flies very well. The cg is near perfect. However I have noticed that my wing does have a tendency to get into a death spiral if I am too severe on the turns. I have gained experience and dialed in some expo, this has helped a lot. I don’t get into spirals that much any more. I am aware that I need to be careful when rolling and banking, more so than conventional planes. Do you think anymore can be done to settle the wing down, or is it just a wing thing?

[minifly]

not sure if the ele-bee already has this, but maybe cutting winglets that droop a bit below the bottom of the wing?

[stone_axe]

Flying wings lack yaw stability and there isn't a lot you can do about it.

Just avoid 'banking and yanking' near the ground.

Winglets and wash-out will help a little.

[Craig Mckinley]

Thanks. I do not fly too low because of possible spiraling. The Elle Bee has winglets that are only above the wing. There is no winglet below the wing. Also the winglets are held on by velcro only, they are sloppy in flight.

[lee292a]

Unfortunately, tip stalling and its associated death spiral is a characteristic of a tapered, swept wing. Washout helps, as does placing the winglet so it sticks a bit below the wingtip. Don't fly too slowly, and don't jerk it around.

[RANSWrench]

I set the rates down on the elevator and keep my weights down. My zagi 400x changed from a tip staller to a no staller by going to lighter battery. I use gp1100X8 packs now. These are also my favorites for 36" wings.

[Craig Mckinley]

Thats interesting, spiralling is really a severe tip stall? I might have a look at some more efficient winglets. I know the Overlord flys beautifully. I wonder what type of winglet it uses? I think we agree that tip stalling is a wing thing.

Thanks for your help.

[THUREN]

Yep.... set the dual rates if you have it... My Devastator can be in a full speed dive, and I can pull all the way up FAST, with no more death spiral... This is what has allowed me to run a full charge with the left stick stuck all the way forward... :p :D

edit: Is this more of a high speed occurrence with your Bee? Low speed?

[Craig Mckinley]

Thanks. I have a Hitec Flash 5. I have setup full rates but with -40% expo on the turn. Seems ok. Please dont get me wrong, the bird flys well, its just coming from coventional planes its something I have to watch out for.
Do you think I need to secure those winglets a bit they do wobble on there velcro when in flight?

Sorry. I thinks its more a slow speed problem.

[dst]

Thats interesting, spiralling is really a severe tip stall? I might have a look at some more efficient winglets. I know the Overlord flys beautifully. I wonder what type of winglet it uses? I think we agree that tip stalling is a wing thing.

Thanks for your help.

My OverLord has 2mm coroplast winglets and about 40% of the winglets is below the wing. The OverLord is thick which gives it more lift going slow and I think that improves its low speed performance.

dt

[asmokindeal]

Try adding a little nose weight. anywhere from 1/4 - 1 oz. Start small and work your way up. That is more than likely your problem.

If this isn't your problem, with experience you will find you have this problem less and less.

One other solution if nose weight doesn't help is throttle control. When you are flying it around slow and you notice it start to tip stall, hit the throttle for a second and stabalize youself....one quick up down. You will gain hardly any speed and it will save the wing.

Also having a good brushless setup makes a difference. You get the power you need when you need it.

I never have tip stalling problems any more and I think it is because:
1. My CG is correct
2. I have enough power to pull it out before it becomes a problem.
3. Throttle management.
4. Experience, I know what it will and won't do at low speeds.

With time you will learn what your wing will do and what it won't. You should be able to get your wing to fly so that your not always worried that it is going to flail out on you.

Rich

[RANSWrench]

Globing a lot of weight on the nose is ok if you have unlimited power like assmoker does. If you have a light wing with modest power, you want efficiency. My wings all have very little reflex in level flight and a far aft cg. I make up for this with low rates on the elevator, but i keep high rates on aileron. Lots of reflex make stability but is paid for with power.

[THUREN]

Thanks. I have a Hitec Flash 5.


Cool.... Me too..... Anyway, I did use EXPO, and it worked well to remove the twitchy feel but the dual rates REALLY fixed my handling problem. With dual rates programed into the elevator function, you are limiting them, to what I would guess to be about 1/2" total travel. This also helped my slope glider a TON as the elevator function was working as a brake, slowing it down even more causing the ol' tip stall... On your flash 5 the little switch on the upper left will turns the dual rates off/on but have fun programming it... :p You will still have full aleron function... :)

[Craig Mckinley]

I started of with a lower epa and then progressed to full but with expo.
As I say, the wing flys well just a bit more experience needed. Placing more nose weight will make it nose heavey but a lot of the guys seem to fly their wings that way. The tip stalling is more an observation than a problem. However I might have a good look at the OverLords winglets.

Thanks

[chainick]

Craig, do not move CG forward.

While it does improve stability it also degrades flying performance. Stall in a steep turn is a "normal" thing. Every plane has its stall speed, right? That stall speed changes with the amount of angle of bank. I fly full-scale gliders and stall and snap those into spins doing steep turns once in a while. The cure is simple - either fly faster for desired amount of bank or reduce angle of bank.

I experiment quite a bit with that subject and curve for bank\stall speed looks like this:

at 33knts I can only fly straight and level (barely)

at 42 knts I can bank glider 30 degrees

at 50 knts I can do 50-60 degrees of bank

and so on.

If you eliminate tip stall with increase of washout or toying with winglets then at some point the whole wing will stall if plane is too slow for the steepness of turn.

[Craig Mckinley]

Chainick. Thanks for the input, very interesting data. I realise its just a wing thing. Asmokindeal indicated that experience is going to help the problem. It catches me out sometimes, but I shall just keep the speed up and not fly too low.

By the way, if I do get into a bad spiral whats the best way to recover?

[lee292a]

Craig, the best way to recover from a spiral is to neutralize the controls, let the plane stop rotating and go into a dive. Then, pull out.

[mando]

I feel that close attention paid to the final setup will all but eliminate tip stalling . I run low and high power setups and have found that dialing them in is more important than power , but no doubt that high power makes it easier .
Installing winglets with 25-30% below that wing is a big help , and I've got to agree with Rich that gradually adding small amounts of weight to the nose can and will be the biggest factor for improvment . The best I have seen with the written word with CG placement , is that it will get you in the ball game for the final set up of getting it "Dialed-In" .

Mando......

[marjamar]

Why prevent them??? Just use them for added fun like this...

"Hey! Watch this..." (http://speedwing.net/assets/multimedia/flying_saucer.wmv)

-Rodger

[flyingflipper]

Craig:

The Ele Bee can be flown with up to 1/3 of the winglet mounted below the wing which will help with the tip stalling but it won't eliminate it.

Check out the directions on Atlanta Hobby's web site. It's an Adobe Acrobat file. I fly my Ele Bee with 2 sets of winglets: 1/5 below the wing and flush with the wing. With the "1/5 below" winglet, I can fly "low and slow" with minimal tip stalling.

By the way, the velcro arrangement is "sloppy" but effective in keeping the winglet on. I'm working on a more secure arrangement that will reduce the amount of flex. I tried rare earth magnets but a winglet sheared off on a high speed dive!

Cliff at Atlanta also sells combat winglets but I don't have any experience with them.

[chainick]

I agree with marjamar, spins are fun. Although on some models its hard to induce spins, for they are so stable and spin-resistant.

Oh, almost forgot, you can intall fenses on wings parallel to airflow, somewhere 2\3 of half-span. Something like those ones you can see on MiG 15 or Sabre, these fenses prevent developing span-wise airflow that is usually happen a moment before spin starts. You can also see the same things on SB-13 flying wing - they are there for the same reason, to improve spin resistance.

[RogWarTheOAP]

Hi Guys, I've just come across this thread.
Have the models in questions got elevons by any chance?
If so then you may have proverse yaw.
I had this on a delta. No rudder so sharp turns were bank and yank. A sharp turn would cause the nose to point straight down. A change to seperate ailerons and elevator cured all.
Thinking about it I came to the conclusion it was proverse yaw.
Put in 'aileron' for a LH bank. The LH elevon goes up and the RH one goes down. Pull up 'elevator' and, if you've got a lot of throw, the LH elevon goes up more and the RH elevon goes back to neutral. Result bags of drag on the LH side and zero on the RH side. The nose pivots to straight down and you get a twisting motion because the 'aileron' is causing a vertical roll downwards.

Don't know if this has anything to do with your problems 'cos I don't know the models.

HTH

[Flyin Hawaiian]

tipstall...what's that? I fly my unicorns daily and none of them display behavior such as is being described here and I bank them 90 degrees

[FoamCrusher]

tipstall...what's that? I fly my unicorns daily and none of them display behavior such as is being described here and I bank them 90 degreesLono:
Cut your 'Corn down to 42" or less and you can discover the wonder for yourself. LOL

Roger:
What are you doing with the sticks to break out of that flat spin?

FC

[marjamar]

I've not flown the minitwin 250 much, but since this flat spin is forced using thrust vectoring, all that "needs" to be done is to stop using thrust vectoring and it will come out.

-Rodger

[FoamCrusher]

Roger:

I didn't realize that was a twin.

I have a Stryker with a Mega 16/15/4 on it that I can put into a flat spin by yanking hard on it with high rates on so the control surfaces get lots of deflection. Once into a flat spin I can't figure how to get out of it. It just keeps on spinning and slowing falling until it hits the ground - not hard, but I would like to be able to pull out and keep flying :D

FC

[Craig Mckinley]

I Think the general feeling here is that while there are some ways of preventing tip stalling, wings by creation do have a propensity to tip stall a little. The answer seems to be a good set-up, preventative flying and experience. It has been a very interesting post. It seems like most of us have had to deal with the problem in some way.

[memyselfandI]

Why prevent them??? Just use them for added fun like this...

"Hey! Watch this..." (http://speedwing.net/assets/multimedia/flying_saucer.wmv)

-Rodger
WHAT The...

[memyselfandI]

I agree with marjamar, spins are fun. Although on some models its hard to induce spins, for they are so stable and spin-resistant.

Oh, almost forgot, you can intall fenses on wings parallel to airflow, somewhere 2\3 of half-span. Something like those ones you can see on MiG 15 or Sabre, these fenses prevent developing span-wise airflow that is usually happen a moment before spin starts. You can also see the same things on SB-13 flying wing - they are there for the same reason, to improve spin resistance.
Is that... could that be... you, in that glorious-looking craft.

[watersharer]

while completely offtopic, I was laughing too hard not to post this...

On the front page, all I could see was "How to prevent death..."

I cannot tell you how disappointed I was when I read the thread.

:)

[chainick]

memyselfandI - what a name! CAnIborroW it sometimes? Answering your question - no, thats not me. I wish..

FoamCrasher - I spin stryker too. Mine recovers by itself once stick is neutralised. You may want to power it out of spin. Or if its "condition" rather then "situation" then try applying elerons in the direction of spin. Or down elevator. If you have lots of deflection then there should be no problem.

[Tr0gTX]

I own an elebee and apparently this is a common problem with these wings. I have an old cut down Zagi 400x, a Great Planes Slinger, and a 60" homebrew Zagnutz, and none of them tip-stall and death spiral like the elebee does in turns.

I installed drooped winglets and decreased the elevon throws - the elevon deflection on this model with the full-size servos is so great that it acts like airbrakes. It improves but does not eliminate the problem - you still have to be on the look-out for it and carry enough ( a lot of ) speed into tight turns. I have also tweaked the CG ad nauseum.

So far I am kinda disappointed in its handling - its much more twitchy and touchy than any other wing I have flown. So far, I cant really recommend it to anyone over so many other excellent wing kits out there

[Craig Mckinley]

Thanks Trogtx I have been hoping that some ElleBee pilots might chime in. Yes, I wouldnt be surprised if there are better wings out there.

[Lee]

All of my wings will stop spinning if I just let go of the stick even hard loops stay in control. If yours will not maybe you have one or all of the following:

Heavy wing loading
Wing too light to penitrate
CG too far back
CG too far forward requiring too much up elevater for level flight.
Too much movement in control surface
Poor airfoil design
Poor motor alignment
Under powered
Trying to fly too slow
Wing is warped or both wings are warped.
Unequal servo throw due to flexing rods elevon design servo mounting problems

Some wings just don't fly well. Try a different wing and see if you have the same problems.

Lee

[Craig Mckinley]

Lee: My wing will self correct when I let the controls go. Had a try today. I guess the problem is that I have tried to correct the problem myself instead of just letting the wing do it.

[Lee]

Evey plane I have ever owned takes some trimming in to get the maximum performance. I will play with weight, CG, elevon shapes and throws, motors and batteries and everything else I can think of until I get the plane to fly the way I like. Tinkering is a part of the hobby to me and I don't give up quickly. Even when a plane flys well I will still try new things to see if I can make it fly better.

I'll throw a plane away, or even worse I'll sell it, if it doesn't fly the way I want.

Don't be easily satisfied and don't be afraid to play with the design and balance of the plane. Don't assume that because a plane is kitted that it will fly well out of the box. It will still need to be tinkered with to get the maximum performance.

Lee

[wingman2004]

I have been flying my first wing for about 4 months and I love it. My Elle Bee flies very well. The cg is near perfect. However I have noticed that my wing does have a tendency to get into a death spiral if I am too severe on the turns. I have gained experience and dialed in some expo, this has helped a lot. I don’t get into spirals that much any more. I am aware that I need to be careful when rolling and banking, more so than conventional planes. Do you think anymore can be done to settle the wing down, or is it just a wing thing?

Craig, Are you sure the cg is perfect? I had a similar problem and discovered that this could be a result of cg too far forward. I removed a little nose ballast and the tendancy to dive in a spiral out of steep turns disappeared. Check out this link http://www.acesim.com/rc/construct9.html.

[Craig Mckinley]

Wingman2004: I will have a look at the cg again. I did spend a lot of time on it. Thanks for the link.

[Rajesh L G]

I maidened my first delta yesterday. It has a very nice glide and quite stable, no twitchiness. Only problem was motor thrust angle, it climbs at a good angle under power. About 15mins into the second flight, I got into a spiral. I had read this thread before, so tried punching the throttle a couple of times, but it didn't make any difference at all. Then tried ailerons, again no difference. By this time I had just about 15ft altitude left so I gave up and left the sticks It continued slowly spiralling to ground. It was a slow fall, so not much damage.

Only thing I didn't do was apply down elevator. Since the plane was already pointing about 70 degrees down, I didn't think down was needed, was I wrong ?

I don't want to stop this spinning, it looks cool :rolleyes: Just want to be able to get out when I want :D

[minifly]

What i think is happening is your rudder is being 'blanketed' by turbulent air coming off your fuselage.

is your delta a pusher? if so it would probably help to go to a puller and add power when you want to escape the spin. this will make smooth air flow over the rudder,making it more effective.

else, i would suggest adding some rudder below the wing, in increasing amounts.
increasing the rudder will make it harder to get into the spin, and easier to get out, so its up to you to get the amount of stability/maneuverability you want.

you could also move your rudder behind the trailing edge of your wing, eg on a carbon fiber rod, but this won't work on a pusher.

[Rajesh L G]

You guessed right, it is a pusher. I don't quite understand what you meant, are you talking about using the rudder to stop the spin ? But this model does'nt have a rudder, just elevon controls. I have twin vstabs midway on either side of the wing on top. I'll post a pic of the plane later.

I did consider putting winglets drooping below the wing, but since I had already moved the battery as forward as possible to get it to balance, I could not afford the weight of winglets at the back. Actually it is not too bad, I made a few slow passes, they were fine. The problem occurred only when I tried to turn when I was too slow I guess.

-- Rajesh