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Roll T/O question

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Roll T/O question

Old 04-27-2008, 03:31 AM
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Default Roll T/O question

OK....I got the PT profile and can get it into the air and fly it around reasonably well. So far I have 5 successful flights however they have been with a run/throw start. I have unsucessfully tried 10 rolling T/O's and they all result in the preautorotation left roll. I understand the entire concept of I'm not fully in autorotation, so what I'm interested in, is if anyone can give me advise on how to get this thing up to speed (rotor head) and stop the left roll. I've tried finger turning it before letting it roll and holding the tail with the engine at full power and full back pressure to get the rotor turning. All attempts were as the manual recomended (half throttle until airborne/long slow T/O roll). Has anyone else had this issue with this model? What am I missing? Should I be applying full forward pressure until autorotation. Should I really be applying full power on the roll?

Any help would be greatly appreciated,
Thanks,
Chris
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Old 04-27-2008, 03:40 AM
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Default RE: Roll T/O question

i was having the same trouble. i put the shims under the blades and it seemed to help a bunch on take off. last 2 trys it was a lot easier.
Old 04-27-2008, 03:48 AM
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Default RE: Roll T/O question

I didn't see any shim's in the kit, but from what I can tell in pictures, they are about 1/16" balsa running the length of the blades. Is this correct? Also, did the shims hurt the performace of the rotor any?

Chris
Old 04-27-2008, 03:58 AM
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Default RE: Roll T/O question

I was having the left flop everytime. once i got it in the air it wanted to climb with full forward. I put the shims on and it was like day and night difference getting it in the air. did hurt the lift a little but I think i needed that for the climbing trouble. I think the sims are smaller than 1/16th. I think they are like 1/32.
Old 04-27-2008, 04:02 AM
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Default RE: Roll T/O question

i know what you mean about the full forward on the stick. I've increased the throws to counter act the pitching up.

Are the shims balsa?

Thanks
Chris
Old 04-27-2008, 04:04 AM
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Default RE: Roll T/O question

do they run the length of the blades?
Old 04-27-2008, 04:07 AM
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Default RE: Roll T/O question

real thin plywood and about quarter inch wide. Maybe John from flying balsa will get on here or joel, they been alot of help for me
Old 04-27-2008, 04:08 AM
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Default RE: Roll T/O question

no i added the to the trailing edge side of the blade mounting bolt as wide as the doubler
Old 04-27-2008, 04:09 PM
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Default RE: Roll T/O question

Would shims be added to the top or the bottom? On top I would think they would decrease the AOA and spin the blades up quicker? on the bottom, I would think that they would add AOA and make it roll over even quicker.


Also, does anyone know for sure the thickness of the ply for the shims on the PT profile???

Thanks,
Chris
Old 04-28-2008, 07:21 PM
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Default RE: Roll T/O question

The rotor must be up to speed before you try a lift off I use an electric drill My Kelllet needs a rotor speed of 630 rpm to get off without tipping to the left . The heli guys at the field used their optical tach to measure the rotor while I was flying by.Rotor speed goes from 650 to 850
Check my video page http://home.comcast.net/~caros/index.html for video of my takeoff proceedure Right now I am using a electric drill that has a top speed of 1500 rpm DOES THE JOB !!!!
Old 04-29-2008, 02:41 AM
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Default RE: Roll T/O question

That's a beatiful aircraft. I hope to get the Kellet one day, but right now I don't have a car big enough to transport it. I assume that's the Arizona model....how do you like it? If looks are all you go by...it must be great!

Chris
Old 04-30-2008, 07:28 PM
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Default RE: Roll T/O question

Use the minimum shim thickness that you can & still have the blades spin up.That way you get maximum lift.

About the take off run you need a steerable tail wheel. Use it very gently, just enough to keep a straight heading into the wind.
I use full back stick to help the blades spin up quicker.
Keep the take off run slow until the blades are spinning fast enough.
keep trying! Hope this helps.
Old 05-11-2008, 03:37 PM
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Default RE: Roll T/O question

Hi Chris, Take a look at earlier posts in this forum regarding prerotator devices. There is a fellow gas-powered gyro fan who easily adapted a speed 400 type can motor and heli overrunning bearing (sprag clutch) for a prerotator. It all mounts on the tilting head very nicely. He uses a heli radio so the throttle hold feature can be used to operate the electric prerotator. From what I hear it takes off in ten to fifteen feet of rollout. Check it out. Hope this info helps. Good luck. Charlie Anderson
Old 05-11-2008, 09:54 PM
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Default RE: Roll T/O question

With the shims i have been able to do rolling t/o's. The rollout is abit long, about 400' at 1/2 throttle, but atleast I can now do rolling takeoffs. But I thank you for the input!

Chris
Old 05-15-2008, 10:29 AM
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Default RE: Roll T/O question

OK, guys, the real thing (Pitcairn-style gyro) could take off in 150 feet or less with a prerotator. The technology for model prerotation has been there for some time now. Takeoffs in 10-20 feet are possible. I don't understand why the folks who designed this gyro won't add the simple prerotator. Why play around with long taxiing, risky takeoffs, etc. when there is a clearly better alternative ??? MAKE THE PT ALL IT CAN BE !!! It is long overdue, from the number of takeoff/rotor spin-up problems I have heard about on this forum. I would buy one if it had a factory prerotator. Charlie Anderson
Old 05-15-2008, 01:31 PM
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Default RE: Roll T/O question

Huh.....weight???? I really don't know the answer. I did find a website were a company was working on producing a prerotator for sale, but they said it was underconstruction/developement. I don't remember were I saw it though....

Chris
Old 05-15-2008, 04:32 PM
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Default RE: Roll T/O question

I've had pre-rotators on my kits for years now.
100% reliable takeoffs, 10 to 20 feet with no hassle,
max performance takeoff in 5 feet. Crosswinds or no wind
not a problem. You can taxi out like everyone else and just takeoff, no
walking on the runway, hand spinning, etc. I think everyone should do it.
Videos of pre-rototated takeoffs here : www.mickeynowell.com

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