Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Deep Impact

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Old 10-24-2009, 08:58 PM
  #1  
freakingfast
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Default Deep Impact

While practicing for the Two Minute Tango warbird race, I was in the third flight of the day with my WM P-51when it happened. I went out a ways further than normal and suddenly lost all control. It went up in a long rolling arc, then strait down at full throttle. The impact from where I stood looked like a confetti popper went off.

Upon arriving at the impact area I found a debris field but no engine. I looked around and then saw the rear tip of the tuned pipe sticking out of the ground. There was this round hole in the ground (the fuselage) and two lines from each side (the wings). I pulled on the pipe and slowly the unforgiving earth released its hold on the OS 70 heli engine.

It seems that the receiver had diminished range and was the cause of the crash. There was no hint of impending problems. The battery pack was still connected to the switch and receiver however the inertia from impact had move the switch to the off position. The pack was bent, but the tabs were still connected so it was tested and produced 6.3 V @ 2 amp load. The receiver and servos all function normally with no apparent damage!
Of course the receiver will be junked and the servos sent in for inspection.

The engine looks great! Amazingly, no dirt was ingested past the throat of the carb even thou it was full open. The crank port was in the closed position at impact. The rear cover was removed and there was a scooch mark where the crank pushed on it. Interestingly the mark shows impact and stop rotation, about 15 degrees.

If I push on the crank there is a tiny detent at one point in the bearings but none when pulled as in running mode. The carb was taken apart to clean. The heat insulator collar came off and stayed in the engine side but the carb will still clamp into position and seal so no biggie.

The header and pipe got modified. Ill cut off the damage part of the pipe and use a longer header to achieve the same tuned length.

Ill bench it and see if the crank lets go or see how the bearings are.

I’m not too sad to see the plane go to Valhalla because it was cursed ever since it took it out of the box. It seemed like the thing was always trying new ways to self terminate.
It’s just sad to miss the last race of the year.
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Old 10-24-2009, 09:47 PM
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combatpigg
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Default RE: Deep Impact

Sorry to hear about your ugly moment, man.....[&o] This is one of those sports where 99.999% perfection still sucks....

I've straightened pipes by making a close fitting bar with a rounded end that could be slid into the pipe.

From now on, take the time to do a full range check with a new plane in your arms and the TX back in the pilot area. Walk the entire area where you intend to fly. You might be surprised with what you find out if your field is in a noisy area. If the controls budge or jitter just a little bit, then you can consider what happened today something that might happen again if the field itself has interference.
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Old 10-25-2009, 12:38 AM
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lfinney
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Default RE: Deep Impact

dang,havent seen a pipe split like that for a long time, sucks to have them pack it in, got that carb on my sx motor too love it, looks like its good to go again
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