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HelicopterBeginners Corner › Cannot gain any pitch after over reving..
09-04-2003 08:07 PM  14 years agoPost 1
kabegalphish

rrNovice

Spokane, Washington

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I have dialed my Hawk Sport in pretty well. I had my LHS guy look and he tweaked a few things. It is a rock solid hovering machine. I basically have two questions/comments.

1. I finnaly found some cahones and rotated the tail around 360 degrees. WOW!! I was so paralized, I did it again 3 more times. (with a break between each to let my sphincter (sp?) unpucker.) I thought that it would rotate around alot faster that it did. It was fairly slow, I thought.
Could it be the heading hold causing it to rotate slower? I wouldn't think so, but I don't know. Or is this a 30 size characteristic?

2. I set up my "stunt" flight mode switch to have a 40, 50, 100 throttle curve, a -3, 5.5, 9 pitch curve. As I am just starting forward flight and nose-in, this is what works for me now. When in "stunt" mode, it flies great with a smooth transition for "normal" mode. But when I land and give it negative pitch, the rotor speed gets insane and wont pull positive pitch. I fix this by switching to "normal" mode and dropping the stick to throttle down. Then everything is fine.

When it over-revs, is there too much centrifical (sp) force to gain pitch? Is JR 537 not good enough for what I am trying to do. These are just things that I have though of. And there is no binding or bent items in the rotor head.

Sorry for the extra long post. And thank you all once again.

Any and all comments welcome!!

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09-04-2003 08:33 PM  14 years agoPost 2
Rick_H

rrKey Veteran

Boulder City, Nevada

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Sounds like you may have dual rates setup on your tail. I fly a raptor 30 with a tt39 in it and I can get it to spin pretty fast.

As for stunt flight mode, I have my Idle up 1 set to -9, -6, 0, +6, 10 pitch curve and V throttle curve of 100, 63, 39, 63, 100 (I am going to increase the 39 today) Anyway that gives me a head speed of about 1740 rpm at hover. I am using JR 537 also and I have had no problems with pitch. I can push some negitive G on the ground and then jump off with pretty good speed for a 30 size heli. My head speed is droping a little at 0 pitch though That is why I am going to increase the 39 today to bring up the head speed. This should give me a little more jumping power.

I would check your servo's and make sure they are not going bad on you.

Rick

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09-04-2003 09:06 PM  14 years agoPost 3
kabegalphish

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Spokane, Washington

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Thanks for the reply Rick_H! I have had a couple of slightly hard encounters with the earth. I shall look into getting some new servos.

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09-04-2003 09:32 PM  14 years agoPost 4
TroyE

rrApprentice

Orlando, FL.

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check your pitch and th curve for your stunt mode.

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09-04-2003 10:00 PM  14 years agoPost 5
kabegalphish

rrNovice

Spokane, Washington

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I set up my "stunt" flight mode switch to have a 40, 50, 100 throttle curve, a -3, 5.5, 9 pitch curve.
Those are my settings-Do I need to adjust?

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09-04-2003 10:05 PM  14 years agoPost 6
daggit

rrElite Veteran

Claremont, MN

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If it's a stock Hawk Sport then you are correct about the centrifical force. The Hawk Sport has no thrust bearings so at high speed the pitch will lock (or move very slowly)

Rick_H has a Raptor (with thrust bearings) so he won't hve the same problem

you will be able to control the pitch at lower head speeds

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09-04-2003 10:22 PM  14 years agoPost 7
James Yeram

rrVeteran

Oceanside, CA

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if you want you heli to spin like a bat out of hell change your atvs to the max with out binding. if you cant make it do it like that put a bigger servo wheel on it.

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09-04-2003 11:17 PM  14 years agoPost 8
shawgl

rrKey Veteran

Murrieta, CA

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What kind of gyro are you using? What servo? The gyro setup can definately have something to do with your tail rotating slowly by way of the setup. When you set it up it needs to have the limits set as far as they can go with right rudder and then tame the piroette rate by bringing your ATV's down or by using your D/R. When I moved my 401 over to my Voyager 50 I was rushing and omitted this step and just made sure I wasn't binding the linkage and had enough travel to counter the M/R torque by just guessing at it. Well all worked well and then I was messing around doing stall turns I just couldn't get the turn rate very fast so when I double checked the instructions I went back and did the Limits and boy did it ever make a difference! Spins like a top! Just something to check. I have worked with the CSM540,560, Gy401 and the 5000T and all have this setup step.

Greg

In God we trust, everyone else we monitor.

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09-05-2003 11:04 AM  14 years agoPost 9
kabegalphish

rrNovice

Spokane, Washington

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I have a JR 460 T gyro, a tail mounted, JR ds 8411sa servo w/ carbon push rod. The atv's are set so nothing binds or breaks. My JR XP 662 radio does not seem to have d/r or exponential for the rudder channel, only elevator and aileron. So that is out of the question. Do I need 3D fins? Or a whole new electronic/ bird setup? I know that this Hawk can perform very well. I am not a 3D'r by any means. I just expected the tail would rotate faster than it did.

As for the headspeed... I DONT want it spinning like a raped ape.
I need to find a fix.

Thanx all for your help

The only bad thing about Nitro is...
... there can never be enough!!

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09-05-2003 06:27 PM  14 years agoPost 10
oldfart

rrProfessor

Vancouver, Canada

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Thrust bearings

daggit,

You have been GRAVELY misinformed. If the pitch on a Hawk "locks up" at increased rotor speed it is ONLY because the two washers on the outside of the feathering shaft (between the outer bearings and the locknut) have been installed improperly. They are to be installed with the smaller one to the inside and the larger one to the outside.

A rotor head that uses 550mm blades (these weigh in anywhere from 85 grams to 115 grams depending on the brand) will not cause a rotor head with two radial bearings to lock up. Even at rotor speeds in excess of 2000 !!!

I have even tested this using 600mm blades that weighed in at 140 grams and could not get them to do so.

Phil Noel

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09-05-2003 06:36 PM  14 years agoPost 11
oldfart

rrProfessor

Vancouver, Canada

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Tail rotor pirouette rate

Your Hawk tail rotor has the power to pirouette your heli and a speed so fast that it would blur. That is unless the t/r is assembled with the tail rotor gears in the t/r transmisiion assembled in reverse. The Larger gear goes on the input shaft and the smaller gear on the output shaft (they are very clear about this in the detailed instruction manual - Step 27/page 20 and step 29/page 21)

The piro rate of any heli is set with the gains and endpoint adjustment on the gyros and the ATV settings of the radio TX.

A GREAT scource for help with your Hawk set-up etc. is the CENTURY forum right here on RunRyder. Accessible from the menu on the right of the mainpage.

Phil Noel

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09-05-2003 07:49 PM  14 years agoPost 12
kabegalphish

rrNovice

Spokane, Washington

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I will check this bird for the potential problems you guys have stated.
I gues I am confused on the rudder/gyro setup. It says to set the servo travel at 150% and have no binding. There would definately be linkage binding at 150%. I guess I have lots to learn and all you guys to hold my hand!!! just Kidding

thank you all

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09-05-2003 08:26 PM  14 years agoPost 13
Cayuse

rrNovice

Music City, USA

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Quote:
I set up my "stunt" flight mode switch to have a 40, 50, 100 throttle curve, a -3, 5.5, 9 pitch curve.
--------------------------------------------------------------------------------

Brian,

It appears that your throttle curve has about 45% throttle at zero pitch. I think this is what is causing your overspeed condition. This is the major disadvantage of having only 3 throttle curve points.

Your two curves match up something like this...

-3 -2 -1 0 +1 +2 +3 +4 +5 +6 +7 +8 +9
40--------------- 45--------- 50 60 70 80 90 100

So, you can see that, if you have 1740 rpm with 5.5 degrees of pitch, you are going to have a whole bunch more head speed with no load and only a 5-7% throttle reduction. Somehow, you need to lower the throttle curve at the point that you have no pitch. This is hard to do with just three points to work with. You will probably have to slide verything up so that you are at near 0 pitch at mid stick and hover at 3/4 stick.

HTH.

Steve (8C>

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