NoWingsAttached
Unobtainium Member
- Joined
- May 21, 2006
- Messages
- 4,871
- Location
- Columbia, SC
- Aircraft
- Air Command Tandem w/ Arrow 100hp; GyroBee w/ Hirth 65hp; Air Command Tandem w/ Yamaha 150hp
- Total Flight Time
- >350
I have hit 90 a couple of times, briefly, while mostly cruising around 80-85 when I am in a hurry. This is IAS, not GPS. My ASI is accurate. But I've never gone faster than ~90 straight and level in my tandem Air Command, sustained for very long.
Once I did two low, high-speed passes, starting at 20 feet off the deck, from the north end heading down RW 18. The first one I kept it at 90 mph for the last half of the distance. The second time I went over 90, hitting 92 by mid-field and sustaining it the entire length until something started to flutter in the rear and I backed it off (control push tubes? I'll need to figure out what made the noise, of course).
Now this was at 8800-8900 RPM, so somewhere in the 135HP range, WOT, typical climb power. I don't know of anyone else who has flown a Tandem Air Command with a similar power-to-weight ratio, and I am wondering if anyone has ever flown one of these (very draggy) AC gyrocopters and been able to maintain over 90MPH S&L like this before. If so, any vibrations? Issues? Safety concerns? Everything seemed fine until I got that flutter...It didn't come through my pedals, I didn't notice excessive stick shake, but did feel it through my seat and heard it outside of my helmet, behind me.
When I flew after that I took it REAL cool, and the stick seemed to have more shake than usual. An inspection of the Skywheels and the rotor head turned up nothing. No hardware was loose, bearings tight the ship passed a thorough ground inspection. The teeter bolt tower bushes are a tad sloppy, probably time to replace them, but they have been that way for a while now and I didn't think it was anything to be too concerned with since stick shake has remained very light & nominal.
I ran the engine on the ground, taxiied up and down the pavement but nothing seemed out of place, no PSRU or engine vibrations or noises. So I am thinking perhaps it had to do with air turbulence...
Any comments or insights would be appreciated, especially from any Air Command specialists.
Once I did two low, high-speed passes, starting at 20 feet off the deck, from the north end heading down RW 18. The first one I kept it at 90 mph for the last half of the distance. The second time I went over 90, hitting 92 by mid-field and sustaining it the entire length until something started to flutter in the rear and I backed it off (control push tubes? I'll need to figure out what made the noise, of course).
Now this was at 8800-8900 RPM, so somewhere in the 135HP range, WOT, typical climb power. I don't know of anyone else who has flown a Tandem Air Command with a similar power-to-weight ratio, and I am wondering if anyone has ever flown one of these (very draggy) AC gyrocopters and been able to maintain over 90MPH S&L like this before. If so, any vibrations? Issues? Safety concerns? Everything seemed fine until I got that flutter...It didn't come through my pedals, I didn't notice excessive stick shake, but did feel it through my seat and heard it outside of my helmet, behind me.
When I flew after that I took it REAL cool, and the stick seemed to have more shake than usual. An inspection of the Skywheels and the rotor head turned up nothing. No hardware was loose, bearings tight the ship passed a thorough ground inspection. The teeter bolt tower bushes are a tad sloppy, probably time to replace them, but they have been that way for a while now and I didn't think it was anything to be too concerned with since stick shake has remained very light & nominal.
I ran the engine on the ground, taxiied up and down the pavement but nothing seemed out of place, no PSRU or engine vibrations or noises. So I am thinking perhaps it had to do with air turbulence...
Any comments or insights would be appreciated, especially from any Air Command specialists.
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