cap snapping
 

Would non-sealed hinge gaps play into this as well??? I don't think I sealed my hinge gaps on mine

cap snapping
 

Which Cap are you referring to?

Jerry

cap snapping
 

Reduce your throw on the elevator to about 3/8" for low rates, that will turn most Caps into a docile bird. Get an Edge or and Extra and eleminate the problem! Pete

cap snapping
 

Check your elevator throw and your CG. To much elevator on a Cap on low rates is not good.

cap snapping
 

Definately not a problem with elevator throw... on low rates with expo, I'm only getting about 3/8" of throw, and it still snaps. I'm thinking that it's a combo of the hinge gaps and the CG being a little off.... It's the Matt Chapman cap 232, Moki 1.8 combo that I have. Sooooo.. do the non-sealed hinge gaps play into this as well possibly??

cap snapping
 

also balance the wing!!

cap snapping
 

Non-sealed gap can play a role in flutter and control surface effectiveness, but IMO will not promote elevator induced snaps.

A reaward CG WILL do it, though.

cap snapping
 

A CG to far aft will cause it to snap ( as already posted). A wing that has a + incidence will do this as well especialy if it's just at the tip (warped wing). Don't ask me how I know! Check your plane over carefully. My GP Cap 231EX (.46 size) was just this way, nothing I could do about it.

cap snapping
 

Tip stalling can sometimes be alleviated by "reflexing" the ailerons. RAISING (that's right) both ailerons 1 or 1.5 turns on the clevis will in effect reduce the wing tips' angle of attack, thereby improving stall characteristics.

If you have a computer radio, you can set this to work only on landing which would preserve the "snappyness" for tumbling maneuvers.

There's a reason the old Cap 21 was called "Snap 21"

cap snapping
 

This is what I had to do on my GP 231EX, it helped some, but the plane just could be a real pain!

cap snapping
 

Do you happen to have dual elevator servos? I have an Extra that was "snapping"... or so I thought. I had one elevator that would move a small amount more than the other. This was causing the problem.

Mike

cap snapping
 

One servo on the elevator with a VERY well supported rod. Had to do this because of flutter. The GP Cap 231EX has a very short wing (LE to TE) which enhances the snapability of the plane.

cap snapping
 

DO NOT REDUCE THE ELEVATOR THROW!
Put an incidence meter on the wing panels (root and tip) and get rid of the warp! Turn the radio on and check the ailerons too, they may be warped. You can add a little washout if you like.
Mike's right, check that the elevators have equal travel at all stick positions, not just full up and full down. I used an MK ball bearing bellcrank to run mine but there are several ways to improve the "Y"'d pushrod.
Raising the ailerons a turn or two can help but make sure that they're straight first.
Additionally, the Cap has a high thrust line and low center of drag, it requires 1-2 degrees of up thrust on the motor. At 0 or negative the plane will balloon when you chop the throttle.
I'm on my 4th and have set up several others with ST 2300, Moki 1.35, 1.8's and 2.10's. All balanced at 25-35% of the MAC, ran +/- 45 deg. (2.5 inches) on the elevator and as much aileron and rudder as we could get. None of the above airplanes had a snap habit once the warps were straightened out. My latest even had - 1.5 deg in the left panel and + 2 deg. in the right. After I fixed it the wing rocking in high alpha stopped.

Chris

cap snapping
 

However, it is the same wing as their Extra which does not have a snapping problem. There is clearly another aspect of the design which contributes to snapping.

cap snapping
 

The one I'm talking about is the ARF version not the kit. I have never seen a 64" wing that had such a short wing cord.

cap snapping
 

Yeah but giders don't have a problem and they have very high aspect ratios.

cap snapping
 

Good point, but their wing loading is much less, that is unless I'm missing something. I don't fly gliders so I'm not up on them.

cap snapping
 

Yeah, the GP Cap 231ex has insuficient wing area, and they fly good if you keep the airspeed up. The arf is not the same wing as the extra.

cap snapping
 

Hey Chriss300s,
What do you mean 1 or 2 degrees on the engine?
And what is ballooning?
I'm getting a CAP and I need to know! :)

cap snapping
 

Paul,

Most Cap's pitch up when you reduce throttle on landing, or balloon, due to the high thrust line and low center of drag. To correct this you add 1-2 degrees of up thrust on the motor mount. The 1/4 scale Cap fly's great with 1 degree of up. Using a meter check that the wing is at 0 degrees, the stab is at 0 degrees and the motor is +1, 1 set of washers under mount on the bottom usually works.
The biggest problem people have with the Caps is the enormously powerful rudder and elevator, it's also its greatest virtue. The design isn't any more prone to "snapping" than an Extra, in fact they have virtually the same wing and the Cap has dihedral to boot! What it does have is an elevator and rudder powerfull enough to stall the wing at any time in any condition, regardless of speed.
Consider a stall being when the wing exceeds the critical angle of attack and stops producing lift. You can do it with pitch or with yaw. Example: During full throttle level pass, apply full rudder and the plane will tuck under in a violent snap roll. During a hard "bank and yank" turn, you apply too much elevator and it'll snap out.
The movement of CG effects the force required to induce these pitching and yawing movements. Like moving the fulcrum point on a lever.

If you keep the Cap light and make sure that it's straight as an arrow it'll be the most impressive flying plane you've ever flown. Most guys that fly them get hooked, you'll love it. Just ask Mike, we've both got the Cap virus bad.

Chris

Lanier CAP
 

I'm currently tuning a CAP 232 Lanier ARF that I bought used. I believe I have once and for all proven that it doesn't save any time to buy a used plane. I could have gotten the kit built and ready to go in this much time - and lighter too.

Anyway, these are all good suggestions. With so little elevator throw, doesn't it take almost all the elevator throw to get the thing leveled for landing? Right now I actually have too much up-thrust, so it dives for the ground at idle. Tough to land that way.

I also have a snap problem - seems to happen to the same direction almost every time. Gotta true this thing up. I already checked elevators - but will re-check. I gotta do the lateral balance as well.

Also, I had a friend suggest using turbulators on the outer wings to help tame the snap. I'm gonna give this a try as well. I'll report the results.

cap snapping
 

John,

The turbulators work well. I have a friend that adds them to everything and amazes people with how docile some of his planes become.
I'd definitely meter the wings and check for warps first. Laterally balancing the wings makes a big difference too.
My friend will try out turbulators by taping some triangle stock or even square stock to the leading edge at the tip.

Chris

cap snapping
 

I also have the GP cap231ex. It is my second. Im just wondering how to add washout to the wing tips on this plane.

thanks

cap snapping
 

The easiest way to add washout is to flex the tip and use a heat gun to take out the wrinkles (it takes about 1/2 hour and two people)
Put a meter on the wing and get a baseline first. Flex the tip - trailing edge up, leading edge down and shrink out the wrinkles in the covering. Continue flexing the tip until the covering cools. Now repeat on the bottom of the wing. Each time you do it you'll find that the wing has "given" a little in the right direction. It usually takes 5 or 6 times on each side.
1/2 - 1 degree of washout is plently. Just matching the incidence between the two tips will probably make a noticeble difference.

Chris

cap snapping
 

JohnG,

I also just bought the Lanier Arf used. The first three flights were perfect but on the fourth it snapped out at the bottom of a loop. I guess to much elevator not enough power. I saved it with very little room to spare and only because I had snapped the simulator enough times to know what to do.

I am moving the CG forward to the factory recomendation untill I get to know it better, changing the rudder to pull-pull so as not to have to add weight.

Other than it scaring the heck out of me I like it so far, especially with the brison3.2.

Richard

no more
 

THe Cap for me was snapping always in one direction, to the right . It wasn't bad either - it usually rolled less than 90 deg. I'm not even sure it was a snap, since it wasn't instantaneous, and I could counter it with aileron.

I had taken all the steps mentioned here, incidence check, lateral balance, small elevator throw, turbulators. However - I started slowly increasing elevator because throw was so low I wasn't comfortable landing it. Pull too much in a left turn, no big deal. Pull too much in a right turn, it'd go over on it's back.

I was getting a handle on nice landings, doing touch & goes when the engine quit on takeoff at 45 deg nose up. Round over the top and pull back hard - no luck. It didn't snap anyways, but it did pancake, hard. One of the wing panels busted in half and flew up in the air. Broke the spark plug off at the base of the ceramic.

It would be reparable if I was interested in trying to true it up - but this plane had too much "personality" plus it was built way tail heavy. I had to put a pound of lead in the nose, along with my Brison 3.2 to get it to balance. I'd rather start over with a kit I can build light & straight from the beginning. I went to Aerowork's site to look at their 29% Edge - and they don't make it anymore :mad:

Anybody in the Central Florida area want a project? Needs a new wing panel, cockpit canopy, and cowl - available from Lanier. Otherwise, needs a few things on the fuselage tighened up and some scrape - repair. You can have it for free....

cap snapping
 

Sorry to hear about your pancake but dont feel to bad Ive got a H9 Edge with the same problems and a Friends got a WM Extra doing it to.
Both are in the shop for repairs.!!!

cap snapping
 

ALL of the " snapping problems " I have seen on these designs --is caused by one thing.
The durn model is just too friggn heavy.
Snappin Caps -originated with the first GP Caps from years back -- they were also WAAY too heavy.
Caps setup at 25% of chord balance- with reasonable wing loadings are super flyers.
I have built kits in various sizes as well as designed them from .40 cu in engine size to 150 cc size
The full scale Cap has had long and short wing setups (Cap 21 -- CAP 232)- all will snap if heavily loaded.
the scale stab setups are both forward and relatively small.
Anyway - the majority of the BARFS I have seen --are overweight -and all of the hinge line sealing etc ., will not solve that problem.
Speed and careful control inputs will keep the abrupt snap from starting --

cap snapping
 

The WM Extra I mentioned is only running an OS 1.6 and single batt pack I fail to see how you could run it any lighter without some serious design changes and theres not much to the WM Extra.
The GP Extra is heavier and I have seen it on gas just sit there and float. When it stalls it just mushes over.
The Edge will float in if you let it and thats not when it snaps.
i see what your saying but I cant believe that the case in all instances.
I have a Giant Stinger that is a porker and it has none of those bad habits doesnt matter how you fly it so some of it is wing design.

cap snapping
 

start with correct cg then lateral balance then make sure your tail pulls up equally on the stabs and follow conservative settings on the up until you know the plane then give bigger throws etc. the problem is, is that we want to 3d these planes to fast.

cap snapping
 

Edge has much more tail moment --better stability -
Stinger has much more chord - effective lower aspect ratio -
different ball games --

cap snapping
 

Dick thats a bit of a sweeping statement



ALL of the " snapping problems " I have seen on these designs --is caused by one thing.
The durn model is just too friggn heavy.

The lightest of the ones I mentioned is the worst snapper.
NOT the heaviest.

cap snapping
 

well - I don't know what weight ranges are on each of the models you have - .
The problems on all of the kits I have seen are directly related to high wing loading.
Loading is -on the ARFS - typically at the max for flying most aerobatic stuff.
On a Cap - it is easy to get the loading too high.
On a " Stinger type "- the loading can be a bit higher.
I see -typically - 1000 sq in ARF models --with wing loadings in the 30's -
tho these will fly --and can be coaxed into large open maneuvers -- the wing loading on a GOOD 1000 sq in aerobat is much better around 22-25 oz ft.
These setups can stand much more yanking around --
I stand by my comment- most are simply too heavy --and many of the heavy ones are tail heavy -
and most of these are ARFS

cap snapping
 

Dick,

1000 sq.in. wing with 74" wing span and 25 oz per sq. ft. loading would be about 11lbs. right?

What model and engine are you talking about?

RD

cap snapping
 

Hey Chriss,
What are turbulators?
And is giving the engine a couple of degrees up always necessary?
And if not how will I know? Will I be able to fly it?
I know a guy who has the same Cap I'm getting and has the same setup
I will,, His plane only weighs 7lbs,, is that too heavy?
The plane I will be getting is the Kangke Cap 232 60 size 62" wing. ARF

cap snapping
 

Paul,

Tubulators are actually devices that create vorticies on the wing that keep the boundry layer attatched. This helps to improve the efficiency of the wing, especially at low speeds (high AOA). Some full sized planes even have them on the prop!
The correct term for what we're talking about is a cuff, or slat. Generally speaking we're sticking something on the leading edge of the wing to increase the chord at the tip. This is to (hopefully) keep the tip flying when the root stalls. We can do this by decreasing the angle of attack on the tip (washout), or increasing the tip chord. Additionally, the large scale guys figured out that a blunt leading edge stalls "softer" than a sharp leading edge. For your airplane you could take a 12" piece of 1/2" square stock and just tape it on the leading edge at the tip. It works, but I don't use them, I'll usually try to get rid of weight first.
Not all Caps need the up thrust, the 1/4 scale just happens to. You'll know if yours does if the CG is within the normal range but the plane climbs while inverted or pitches up with the power off.
From what I've heard the Kange Cap is a great flying plane, I wouldn't expect any problems, just keep it light. Don't put a heavy engine, big fuel tank, dual servo's or lead on it. Just fly it, leave the leading edge cuffs for another time when you're bored.

Chris

cap snapping
 

pattern designs fall into the 25 oz ft region-
I design/scratch most of my planes -so I do the IMAC stuff in the same wing loadings -- huge difference as compared to the heavy stuff.
Look for better wing loadings as the BARF importers get their crappola together.

cap snapping
 

not worth the comment.

cap snapping
 

Dick, when is the 100" Dalotel going to be out? Your small version looks quite light for its size and if its as good as you say it is, I can't wait to see how you like the larger version!

RE: cap snapping
 

I have just finished building a Kange Cap, I really don't even know if kangke has the right denomination for this plane, since they claim it is a Cap 232 while the color scheme and everything is related to the 231 EX. Anyway before buying the related items for the plane I read several posts on the plane and I thing I did good doing this first. Apparently this plane was found by everyone tail heavy so a lot of weight was to be added if you used the recommended engine sizes. The plane can take (apparently) a .90 engine, but if you do a little searching you can see that many people are installing bigger engines to avoid adding weight. I personally installed a TT 120 Pro with pump and pitts muffler. Although I have this big engine up front, and I have less weight on the tail because I used a dubro pull-pull on the rudder, I am still tail heavy, not much but I still have to put the battery pack, a 6V 2000Mah, forward of the CG by at least 2!QUOT!. No added weight other than that but this plane is tail heavy, A LOT. I haven't tried it yet since I am waiting for some hi- torque servos for the rudder and the elevator. I think it is a really nice plane, and by the way the total weight of it is about 8.8 lb so I am a bit heavy but I can't seem to understand how could I have less weight respecting the CG.