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HelicopterThunder TigerOther › Need advice on reducing head speed.
03-12-2003 05:17 AM  14 years agoPost 1
Rick_H

rrKey Veteran

Boulder City, Nevada

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I am stumped, I have a Raptor 30 V1 and have recently installed a TT39 engine in it. I have just read Ray's Authoritative Helicopter Manual and setup all my linkage following Ray's recommendtion 90 degree angles. I have setup the ATV's following his advise. I am running 3/4 stick hover at 50% throttle open. My problem is I can't get the head speed down. It is running between 2000 and 2200 RPM, I have tried lowering the throttle curve and increasing the pitch curve and I can get it down to 1800 RPM but it is at 38% throttle curve and +8 degrees of pitch. It hovers but is hard to control, at 2000 RPM it flys great but sounds like the blades are going to fly off. I have tried to richen high end carb setting but then again the engine runs sluggesh. I have tried adjusting the low end carb settings also. I am thinking it is a combination of both the high and low carb settings. I need some advise, what can I do to get the head speed down?

My current settings.
Pitch in normal mode
L = 20.5% = -4 pitch
1 = INH
2 = 46.55 = 0 pitch
3 = 67% = 6 pitch
4 = 100% = 10 pitch

Thro Curve
L = 15.5
1 = 27%
2 = 35%
3 = 48.5%
H = 100%

TRVL ADJ. ATV's
THRO H 64% :: L 64%
AILE L 100% :: R 100%
ELEV D 100% :: U 100%
RUDD L 100% :: R 100%
PIT H 150% :: L 150%

Thanks for any advice

Rick

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03-12-2003 05:39 AM  14 years agoPost 2
psawya

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Woodinville, WA

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What does your throttle curve look like? Also, try to get a better mechanical setup on the throttle to make your throttle ATV's near or at 100%. That will give much better resolution on the throttle channel.


Pete

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03-12-2003 05:44 AM  14 years agoPost 3
Airman98

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Southern Illinois

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I ran my raptor 39 at 50% throttle and 5 degrees pitch for 1800 RPM. Dont use mixture to set RPM, set the engine so that it runs good then adjust pitch or throttle to get the RPM setting you want.
Tim

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03-12-2003 05:56 AM  14 years agoPost 4
Rick_H

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Boulder City, Nevada

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Pete

I was following Rays Manual and he recommends setting the throttle ATV levels between the throttle between 55% and 70% so the throttle leads the collective. I will try going back to 100% to see if it helps.

Rick

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03-12-2003 06:02 AM  14 years agoPost 5
Rick_H

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Boulder City, Nevada

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Airman98

What did your throttle curves look like, to get 1800 RPM my curve is around 38% at 3/4 throttle at +6 pitch then jumps to 100% that leaves 64% the last 1/4 of throttle.

Rick

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03-12-2003 06:21 AM  14 years agoPost 6
psawya

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Woodinville, WA

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Here's some good info on throttle setup:

http://www.ronlund.com/throttle.htm

Pete

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03-12-2003 06:48 AM  14 years agoPost 7
Rick_H

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Boulder City, Nevada

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Pete

Thanks, I will give it a try.

Rick

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03-12-2003 09:52 AM  14 years agoPost 8
Al Magaloff

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12,199 Posts- Enough Time Wasted. See Ya!

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Rick, Pete is right on. Adjust your servo arm length so you can maintain the ATV's at 100%. There is no longer any need to lead the throttle ahead of the pitch. When you run ATV's down to near 50%, you have effectively cut the resolution in half. This is one area of Ray's manual that needs some work.

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03-12-2003 12:51 PM  14 years agoPost 9
KenJ

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Ohio, USA

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Best Fix

If you have some extra cash laying around just buy a GV-1 and put it in!

I have started using them on EVERYTHING, including my drag race machines.

It really makes things safer and easier.

Heck, even my car has cruise control?

Ken

Team Horizon

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03-12-2003 12:59 PM  14 years agoPost 10
z11355

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New England

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increase the ATVs like others have said.
64% isn't enough. Adjust the servo
arm length as required. Make sure
you have a parallelogram setup.

bring down the topmost throttle point. The current 100% setting is WAY too much. Just a quick quess... 70-80%

You dont need +10 top pitch.

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03-12-2003 01:49 PM  14 years agoPost 11
Raymond

rrApprentice

Northern Ireland

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I can get it down to 1800 RPM but it is at 38% throttle curve and +8 degrees of pitch. It hovers but is hard to control
Do you mean the heli is unstable or the throttle is hard to manage ?
Just a quick thought, are you sure your tacho is accurate ?

Raymond

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03-12-2003 01:54 PM  14 years agoPost 12
Airman98

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Southern Illinois

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My throttle curve was fairly straight. I think around +9 or 10 at full and +5 at half. I hover at mid stick.
Tim

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03-12-2003 03:40 PM  14 years agoPost 13
Rick_H

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Boulder City, Nevada

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Good, Lots of advice and things to try. I have been learning a lot the past month on how to setup and tune the raptor. I am also finding out some things don’t work.

I have the bicycle tach and have tested it against a helicopter Optical Tach and it was dead on.

Raymond, It was unstable as sluggish it felt like I was all over the place I had trouble keeping it level. It definitely was not too touchy.

I will change my ATV to L100 H100 and re-set the linkage.

Z11355, I don’t quite understand why the topmost throttle point at 100% is to much? Why wouldn’t you want full power at max pitch for clime out? Wouldn’t you risk a flame out at 70-80% at max pitch?

Thanks for all the help

Rick

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03-12-2003 03:44 PM  14 years agoPost 14
Obsessive

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41.73N 71.41W

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If you've got +10degrees pitch and it's still at 2,000 RPM, you simply must reduce the top end throttle curve point until you've "peaked" at around 1800 RPM (or whatever your target is).

BTW, what pitch gauge are you using? Are you sure it's accurate? Most people don't have the "trouble" you're having...not saying you're not having the trouble you say you're having, just unusual.

Also, what blades? Are they at least 550mm?

I've got a V2 with TT39, I run -10 to +10 pitch. Can't say what my throttle is actually running at, since I'm using a governor. I run 1550, 1700, and 1850 rpm in three flight modes.

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03-12-2003 04:00 PM  14 years agoPost 15
z11355

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New England

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you want constant headspeed.

I have a Rap w/ TT39 (well, I did as
it is in for warranty service (threw a
bearing)).

The throttle curve in Normal maxes out
at about 88 (0 pitch point is 55).

If the engine is too strong (ie. not
enough load from the rotor system),
you'll simply overspeed the head and
all that nastyness.

You have a huge increase in throttle
between hover and full throttle and,
IMO, too much pitch (usually only need
around 5ish) and low resolution on
the servo due to a bad choice of servo
arms. It's not suprising that the
machine is very touchy and a bear to
manage.

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03-12-2003 05:41 PM  14 years agoPost 16
Rick_H

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Boulder City, Nevada

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Well from what everyone is saying I made a bad choice following the recomendations in Ray's manual for Throttle ATV's.

I am using the Thunder Tiger Pitch Gauge, and 550 Symmetrical Fiberglass Blades.

Z11355 when you say
IMO, too much pitch (usually only need around 5ish)
I assume you mean at hover? not top end pitch.

As for a bad choice of servo arms, I had to change the servo arm to obtain the 55% to 70% that Ray's manual recommended. I will have to change the arm to get back to 100%.

Thanks for all your help, I will let you know how it all works after I make the changes.

Rick

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03-17-2003 01:47 AM  14 years agoPost 17
Rick_H

rrKey Veteran

Boulder City, Nevada

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Well, I reset my ATV's though I could only get H80 L80 using the stock throttle arm on the TT39 and maintaining the parallelogram setup. during a break in the rain today I ran her up and got 1730rpm at 3/4 stick 50% throttle and +5 pitch.

Thanks for all your help.

Rick

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03-20-2003 01:50 AM  14 years agoPost 18
jeff donovan

rrNovice

Louisville , Kentucky

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Did you reduce your pich atvs also. How do you set you throttle to maintain the parallelogram setup. I have the same exact problem with the version 1 with a TT.36. My pitch endpoints are 140L 140H.
My throttle was at 70L 70H I since have changed this to 95L 95H.
But i still have the overspeed problem.

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03-20-2003 04:17 AM  14 years agoPost 19
Rick_H

rrKey Veteran

Boulder City, Nevada

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How do you set you throttle to maintain the parallelogram setup
I took out my engine then marked the carb with a pen at the 0% - 50% - 100% throttle points. Then I installed the engine and held a stright wire between the center points of the carb linkage and the servo arm screw. Set the throttle on transmitter to to 3/4 stick 50% output and moved the throttle arm to the 50% mark I made on the engine. Connected the arm to the throttle and used the stright wire to find the parallelogram and where I needed the mount the link on the servo arm. Then I set the ATV's. I wanted 100L,100H but found that would require a longer throttle arm to keep the parallelogram setup.
Did you reduce your pich atvs also
No, I left the ATV's the same 150L,150H, I adjusted the pitch curves instead.

Rick

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03-20-2003 04:42 AM  14 years agoPost 20
rockier

rrKey Veteran

Las Vegas

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Rick_H once you get the throttle set add collective in tell the head speed is where you want it. It does not matter what the % is set at. Some helis hover at 5% and some at 7%. It all depends on the throttle curve and how much collective you have at hover.

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oo0---(_)---0oo

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HelicopterThunder TigerOther › Need advice on reducing head speed.
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