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PS-5C stumble repaired with pics

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saber25

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Location
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Hello to all,
I want to post a follow up on my PS-5C carb stumble and failure to accelerate properly. My problem with the carb became evident the day after the Pitts was delivered to my home field. I had planned to fly it when I noticed the engine would not accelerate cleanly. I made the decision to delay my first flight in the S1S until the carb issue was resolved. The unit was sent to Aircraft Accessories in Tulsa and I explained the problem over the phone to Steve, one of their expert technicians. After completing the initial bench check he called to advise me that the unit would need to be looked at and disassembled. It turns out that some parts in the PS-5C were mismatched and that caused erroneous fuel flows. Just eight days later I had the carb back on the plane and she started on the second revolution. I made a small idle speed adjustment and the engine now follows the throttle properly.
A short history on this Pitts, it was built in 1971 and went through several owners here in Colorado so she was high and dry and no corrosion anywhere. The last owner recovered the plane in 1994 and also had the engine rebuilt with 10-1 pistons by Dick DeMar of Firewall Forward. They set her up to race at Reno and in 1998 she won the silver class. This little yellow bird has minimum equipment with a starter, battery and a small ICOM radio. A Grove aluminum gear was installed during the 94 rebuild with a Haigh tail wheel unit. The engine is hooked up to a Sensenich 76EMB-0-60 and she climbs spritely at our field elevation of 5400ft. Cover is Dacron and paint butyrate dope and paint. I like that since it’s easier to repair.
Since last Friday I’ve flown her five times, flight endurance about 30 minutes each, exploring her aerobatic capabilities and then working up courage to get back into the pattern J With 12 landings and three landings which were acceptable I can verify another posters comment about 300 landings before feeling a bit more comfortable. At idle power and a looping turn to final with a slip added in, it reminds me of 180 degree autorotations in the TH-55 or Hughes 300 while in flight training in 1970. The gear does seem very stiff and feels like landing a three legged bar stool. Each landing is full stop so I can savor the Pitts moment and return for another take off. This also gives me a chance to catch my breath.
Observations and questions…. I already talked to Eric about what I perceive to be engine/prop vibrations I’m not used to, having flown behind a wood or composite prop on light planes for thirty years. Do the fellows with the aluminum prop feel a noticeable difference in vibration levels when flying one verses the other? My RV4 runs like a turbine behind the Catto two blade.
What tire pressure seems to work best on the Grove gear? Is there a pressure which is optimum for this stiff gear or do I just get on with it? With over 3500 hrs in tail draggers this little bird presents a new challenge and like the cowboy, plan to keep at her till the eight second horn blows and any suggestions are appreciated.
Cheers,
Hans


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