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Model Rectifier Corp . PowerHelis . JR-Spektrum

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Scale Model RC Helicopters > Gear Ratio of 5 Blade Raptor 50
 
 
Ironside
Senior Heliman
Location: Baltimore, MD

I have a Raptor 50 with a Century 5 blade head and an OS50 Hyper on it that I plan to put into a MD530 fuselage. At this point I have only hovered it. I tried different head speeds from 1100 to 1600. I found that around 1450 it was nice and stable but the engine definitely felt that it could use more power. So I bumped the headspeed up to 1600 and it did okay until I was floating left and right and attempted to move slightly forward and backwards. At the point of transition from slightly moving forward getting ready to float backwards, it literraly looked like the head was going to shake/flap itself to death once I pulled back on the elevator. I immediately hit throttle hold and floated it down to a safe landing. All of the blades are balanced at the proper CG and weighted to within (.3) grams of one another. After reading posts on multiblade heads and finding out that the head speeds need to be kept down, I'm just wondering if in fact the fast head speed caused the flapping and if so if you guys thought it would be wise to try and different gear ratio. The highest that I could put in would be 9.56 (9T pinion and 86T Main Gear Spur). I figure at this point I could get a headspeed of 1450 (maybe 1500) and have a RPM setting of 13862. Just throwing ideas around. I also would like to hear from anyone that has a 5 blade head setup on a R50 to find out what setup you guys are running. Also does anyone know if there is a speed up gear for the tail rotor of a R50? Obviuosly I want to keep my tail authority up.
06-23-2008 04:32 PM
 
 
Rodan
Senior Heliman
Location: Prescott Valley, AZ

I haven't tried it myself, but have a TT MD530 with the OS-50H and have given it a lot of consideration. The two primary problems are that the Hyper motor makes it's power at 17K rpm, and the limited gearing options for the R50. You've already figured out what your best bet is, and that's using the R30 gearing to drop the headspeed. I never found anyone that actually tried it, so I honestly don't know if it will work, but it's really the only way.

I would try to stay above 16K on the motor, and run 30% fuel, or it will likely get hot lifting a scale heli, especially with the torque load of a 5 blade head...
06-23-2008 09:52 PM
 
 
Ironside
Senior Heliman
Location: Baltimore, MD

Yeah I agree. I went ahead and bought the gear set today and hope to get to try it out this weekend. We'll see how it goes.
06-23-2008 10:40 PM
 
 
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Scale Model RC Helicopters > Gear Ratio of 5 Blade Raptor 50
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