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HelicopterMain Discussion › Dreaded Raptor 50 Tuck
05-06-2005 06:52 AM  12 years agoPost 1
Santiago P

rrProfessor

South West, Ohio

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I have read a few threads on the subject, and is still unclear to me why the $!@$*%# R50 does the tuck from hell once in a while. Last time it found terra firma.
First time it happened I was using the light KSJ paddles with slightly rounded leading edges, and stock TT carbon blades. Gone are the KSJs.
Second time was with the stock TT paddles and Mavricks blades while in FF and with headspeed of 2050. It took all the aft cyclic stick and then me pumping the collective from pos. to neg, to pos. to bail out of the tuck-and-dive. I switced to drilled TT paddles with good results. Faster than the stock, no as pitchy as the thin paddles.
Four gallons later, it did it again coming out of doing consecutive rolls (RPM ~1900) into FF and tucked, all the way to the ground.
All along, I've been paying attention to paddle alignment, and all the linkages are practillay new, with no slop. CG is neutral with fuel.

One more incident; before I bought my R50, I got to fly a friend's R50, which at the time just received a MP2. I punch the collective to see an very impresive climbout and then pushed to FF. I carried a pretty high RPM and then, you guest it; it tucked and held this dive from hell til I almost bend the TX stick. Once recovered I landed in a hurry and gave it to the friend with my heart on throat saying, "dude, I just got radio hit and lived". I guess now it was not the radio.

Any help or comments will be appreciated.

$pit

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05-06-2005 07:34 AM  12 years agoPost 2
Billy Zimmerman

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Rainier Oregon

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Check that your canopy isnt coming unlatched and jamming your swash, the v2 canopys have had this problem. Put a screw through the bottom latch into the landing gear to fix this.

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05-06-2005 12:22 PM  12 years agoPost 3
JuanRodriguez

rrProfessor

The Villages, Florida

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Never heard of such a thing..... there are LOTS of Raptors flying in our area....

I would look for some mechanical or electrical problem as what you describe is definitely not common....

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05-06-2005 01:33 PM  12 years agoPost 4
armageddon

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N. Y.

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Billy Zimmerman
Check that your canopy isnt coming unlatched and jamming your swash, the v2 canopys have had this problem. Put a screw through the bottom latch into the landing gear to fix this.
I second that..

I had the same thing and this was the reason.. After screwing in the canopy, it has been perfect.. Now I crash for different reasons..

.

WHAT SIGNATURE?

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05-06-2005 01:36 PM  12 years agoPost 5
Phranque

rrApprentice

Wherever you go, there you are.

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Some info here on RR about it. Put your heli on a table, hold it down with the head, and then lift up on the nose of the canopy. If it moves up fairly easily into the swash, then this could be your problem. What I did was to put the canopy on the heli, and drill a pilot hole through the clip & the landing strut (for alignment). Screw an M3 (or similar) bolt into the strut, and drill out the pilot hole in the canopy clip big enough to fit over the bolt head. Works like a charm.

Flying a heli is like seeing the Matrix, it is a mind bending experience.

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05-06-2005 02:04 PM  12 years agoPost 6
midwestpilot

rrElite Veteran

Crystal Lake, IL

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yes...this is not the tuck people are talking about

when the heli tucks it is a small nose down movement that tends to screw up your flight path and make you pull back slightly on the cyclic to keep the intended path...I don't think the "tuck" described by others would take a heli into the dirt unless they were going FFF inches off the ground.

You have someother issue...the canopy as stated above is a likely canidate.

In life there is no spacebar!

Rich Erikson AMA 6175

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05-06-2005 03:01 PM  12 years agoPost 7
AndyH

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Rockledge, FL

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The infamous Raptor Death Dive!!! I've seen it happen a few times!!

You can either secure the canopy with a screw or simply move the canopy clip back about and 1/8th of an inch back (redrill the holes) This changes the geometry of the canopy mounting and will keep it from coming up and fouling the Elevetor arm.

Sorry!

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05-06-2005 06:14 PM  12 years agoPost 8
drdot

rrElite Veteran

So. California, Orange County.

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My two cents..

Do a search, there's a much better way to prevent this...All it takes is a 1/4'' dowel and about 5 minutes, no canopy mods at all...

John.

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05-06-2005 06:59 PM  12 years agoPost 9
clearsky

rrApprentice

connecticut

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what what what

What the hell is a tuck ?

Keep'um in sight

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05-06-2005 07:10 PM  12 years agoPost 10
Billy Zimmerman

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Rainier Oregon

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the canopy will come up and jam the swash usually tilting the swash forward sending your raptor into a death dive straight into the ground.

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05-06-2005 07:29 PM  12 years agoPost 11
YSRRider

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usa

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who comes up with these words??????


reminds me off that commercial, forget what car, think it might be a ford, and that dorky homo keeps calling the car "clutch" and the broad selling him the car says "no sir, its an automatic" and he says "ya, its "CLUTCH"!

what the **** does clutch mean???????

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05-06-2005 08:01 PM  12 years agoPost 12
rcnuts

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Millersville, Penna

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Very interesting stuff! I too never heard of this "tuck" thing. I HAVE heard however, of canopys coming lose in the front and jamming the swash. If thats what happened, that sucks! I use a hex drive sheet metal screw and a washer on the front clip on my Rappy 50. The screw threads right into the landing gear strut. Takes seconds to remove, and no way for the canopy to come lose in flight.
Harris,

Hooligan, at large

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05-06-2005 08:54 PM  12 years agoPost 13
Dave-Yost

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San Diego, Ca USA

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What servo's are you running? I am new to this heli stuff, but am 16 year RC Planker with a heavy Aerospace/Flying backround. I had the same problem with my Raptor 30. I changed CG, checked and re-checked the rigging/ flybar paddles and the canopy but no change. When ever I came out of an agressive vertical manuver the heli would Tuck over, which would lead to an over-reaction on the stick input, PIO's and so on. I was at my whits end with it. This was a used Raptor 30 with STANDARD JR servo's all around. I finally moved up to a Raptor 50 SE (Hyper), and went with all high end, much higher torque servos and the problem all but went away. I have only noticed it once in some 40 flights on my SE, and it happended while I was recovering from a huge big sky loop and adding colective at the same time. I am convinced that it is caused by a combo of high Aero/G loads over powering the pitch servo. I don't know alot about Heli aerodynamics, but I do know that retreating blade stall is caused overspeeding( or exceeding VNE limitations) on full scale helis. Not sure how it relates to models, but it could be that the retreating blade is experiencing a loss of lift at high speed, and the force is acting on the pitch axis due to gyroscopic affect. I also found that the Raptor likes to track slightly nose low in forward flight, causing me to want to add back cyclic. Go with a higher torque servo on the pitch, add about 20% expo in Idle up 1 and relax your pitch inputs on recovery and the problem will go way.

Well almost!

Raptor 30
Raptor 50 SE
Fury Extreme under construction
To many planks to list.
EMB120, B737, Predator Programs.

Raptor 50, OS Hyper, MP2, TT Carbons, Ex pilot ATP B737, EMB120, Predator UAV Programs, Parrot head

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05-07-2005 03:54 AM  12 years agoPost 14
ErichF

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Sutton, NH

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Retreating blade stall isn't much an issue with RC helis due to the blade speeds we run. We'd have to be flying REAL fast to encounter a true blade stall relatec to retreating blade. Also, retreating blade stall results in a rolling moment into the stalled side of the disc.

There is something Aerodynamic with Raptors in very fast forward flight. During drag races, my R60 would want to tuck to the belly during the entire run (full collective, 15 degrees positive). I had to maintain about 1/4 stick BACK to keep it from biting the dirt. Made it interesting when it's screaming along the deck at 75mph, still in ground effect

I would agree that in this situation, the swash jamming theory is correct.


Erich

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05-07-2005 07:01 AM  12 years agoPost 15
alvinrc

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Mobile, AL, USA

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I did not know it was called the "Tuck", but have encountered it before.

My Raptor does have a tendency to nose down in FFF.
More so than in other type/brand choppers I have flown.
Keeps me on my toes during fast straffing runs.

I read in another RR topic that some mod to head to reduce the "Hiller" (flybar) input to the "Bell Hiller Mix" ratio would go a long way towards fixing this flight problem.

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05-07-2005 03:39 PM  12 years agoPost 16
Santiago P

rrProfessor

South West, Ohio

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EURETRA!

To answer some of the questions: the canopy remined latch during the dive, I could see it well; I an running 83oz/in servos (plenty for an R50); no blade stalled occured, in fact, you would not believe how SMOOTH is sounded as it was going in. When it occured previously and recovered, the canopy remained latched.
And why I called it tuck? It was the first simple word that came to mind to describe the pitch down moment followed by a steady dive. Actually the steady dive is a product of the pilot pulling aft to recover, but in my case that was only enough to neutralize the fwd rotation. Thanks Billi Z and the others for helping me explained what we thought hapened. God forbid I use a sport term analogy again to describe a crash.


I think I found the problem:
Too much play from the flybar craddle attachment to the main hub.
The bearings were the craddle pivots are moving around, not only causing lead-lag but twisting of the whole flybar assy under load.
When it does, it tends to lag and twist to were it favors the pitch down moment, and you no longer have total control of the flybar. My previous experience with XCells spoiled me since when they created lead-lag slop in the flybar the effect on the rotor response was negligible. Apples and oranges I suppose.

Solution: new main hub, preferely an Alum. one.
I will be latching the new canopy as you guys recommended, no taking chances there;
and for those slow ones, I misspelled eureka on purpose.


Thanks to everyone for your comments!

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05-08-2005 06:17 PM  12 years agoPost 17
drdot

rrElite Veteran

So. California, Orange County.

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My two cents..

Been playing with Raptors for a while, and this sounds like one of those tricky problems...Because the Raptor head is a 1/1 flybar ratio, any input to the flybar translates to a similar input to the blades...If the linkages to the head, and the head links are not symmetrical, it's possible to get a condition which allows blade tracking in a static condition, i.e. hover, and yet introduces instability in a dynamic condition..Imagine one link from the swash two turns longer than the other, with a corresponding shortening of the blade grip link to compensate..while this system will track and hover, any flying condition will show instability in the head...Look at the swashplate after tracking and trimming in a hover..If it is noticeably out of level, I'd suspect this is an issue. (unless you are trimming the heli in a gale!)

John.

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05-11-2005 04:27 AM  12 years agoPost 18
Santiago P

rrProfessor

South West, Ohio

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canopy mod? so many...

Thanks drdot,
The Raptor is back and the air, and after 5 tanks I found that the problem with the excessive play in the fly bar was not premature wear, or damage from hitting the ground twice now (ouch) it was operator error. Embarrassing enough, 2 of the screws on the assembly were backing out, and I did not catch it thinking that I did checked everything bout 2 gallons ago. After tightening the entire assembly, it is now responding very predictable. I even put the fearsome KSJ paddles like Furious Raptor pointed out, (now I know the aft setting is called "suicide hole") did a few full bore low passes without any porpusing or pitchyness.

So now I am ruling out that the crash was the flybar fault, and convinced fully it was the canopy. I am bullsh**ing myself if I say again "I saw the canopy was still on". After checking how little tilting up it takes to jam the swashplate, I know I could not tell from 100' if the canopy became unlatched.
I wish I've known about this problem before. I fly among a bunch of people who own raptors, but only one (Phranque) flies regulary. I wish I listen to him when he moded his canopy, better than when I told him tail blades longer than 85mm= eventual tail rotor departure.
Now, if I had good set of blades to fly with. I hate the curent TT carbons It has now.

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05-11-2005 02:16 PM  12 years agoPost 19
rob10000

rrKey Veteran

Western Massachusettes

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Thanks for coming back and wrapping up this topic. Not everyone would be man enough to admit a problem was their fault.

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HelicopterMain Discussion › Dreaded Raptor 50 Tuck
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