Help me figure out what went wrong - RC Groups
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May 01, 2006, 01:51 AM
Rocky Mountain High and Higher
PROACE's Avatar

Help me figure out what went wrong

I finally finished building the Dumas DV-20 with an OS .21-M inboard. It was the first run of the engine break in. I had just come out of the first turn and opened up the throttle everything seemed OK until midway then the engine sounded like it went lean the boat then really went like it had a jet engine afterburner. The boat then appeared to go up on the prop and it did a torque roll like an airplane then flipped end over end.
I am not experienced so I cannot analyze what happened. The boat seemed to be running flat and tracked straight. I have the trim tabs as was suggested and the prop is parallel to the boat center line. The is balanced midway on the hull length.
Thanks for any help you can give me and as always all help is greatly appreciated.

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May 01, 2006, 07:18 AM
Registered User
More info required, do you have a tuned pipe on the motor?
It sounds like a basic blow-off, speed too high for the set up.
If the engine is piped then you just experienced it "switching on".

(just a grammatical edit)
Last edited by w3bby; May 01, 2006 at 06:36 PM.
May 01, 2006, 03:41 PM
RC boat Rock Star
It could be 1,001 things. You could have caught a gust of wind, a wave, hit some object just under the surface and like w3bby said, it could have gotten on the pipe or leaned out enough to give it a sudden burst of speed. It's one of those things that's really kind of hard to know from where I'm sitting.
May 01, 2006, 11:43 PM
Rocky Mountain High and Higher
PROACE's Avatar
Water was calm and no breeze. The boat weight ready to go is 3lb 12oz and the length is 25 inchs bow to stern. Yes I have a tuned pipe with flex shaft drive and a dumas brass prop 1.625" diameter, 2.5" pitch.

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