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The 'What did you do in your workshop tonight?' thread

Snoopy1

Snoopy1

640cc Uber Pimp
Well went to the field yesterday to do a maiden on the 20cc Edge. Sorry to say it lasted about a minute. Took of ok it started to climax and was vertical in seconds. Started trimming to stop the climb and next thing it is pointing straight down at about 3/4 throttle. I pull up and it rolls over. Cut the throttle for second still heading for the ground. Try to pull up again and started to roll over again relaxed on the elevator but by that time I was in the ground. Do not know quite what happened. This is the second time. Can not blame the radio everything worked as it should. The first time was the same thing minute later I was in the ground looking at my self and said what just happened. Well I am in the workshop cleaning everything up and double checking everything, hoping to find something. But it will not be rebuilt and it is going into the trash can.
 

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Bartman

Bartman

Defender of the Noob!
@Snoopy1 is that your design? Was it based on anything specific? I see the elevator goes to the tip of the horizontal stabilizer and is more than half of the chord. With those proportions, when the elevator deflects it changes the angle of attack of the elevator drastically. I just crashed an Aeroworks Stingray that had steeply swept tips which made the ailerons a very high percentage of the chord at the tips, the worst place to have that! Whenever it got slow if would stall and fall off badly to one side or another. I'm just guessing but the horizontal stab tips jumped out at me and that would explain the odd behavior, maybe. Sorry it crashed on you, sucks to lose a plane after putting all of that work into it.
 
Snoopy1

Snoopy1

640cc Uber Pimp
Bartman said:
@Snoopy1 is that your design? Was it based on anything specific? I see the elevator goes to the tip of the horizontal stabilizer and is more than half of the chord. With those proportions, when the elevator deflects it changes the angle of attack of the elevator drastically. I just crashed an Aeroworks Stingray that had steeply swept tips which made the ailerons a very high percentage of the chord at the tips, the worst place to have that! Whenever it got slow if would stall and fall off badly to one side or another. I'm just guessing but the horizontal stab tips jumped out at me and that would explain the odd behavior, maybe. Sorry it crashed on you, sucks to lose a plane after putting all of that work into it.
Click to expand...
It was purchase as an ARF. From prorc as I said before first flight lasted about 1 to 2 minutes. Pranged the plane built a new fuselage and reused the tail and wings, same proportions and measurements just a new fuselage. Well the same thing happened with it the second time both times standing on the flight line saying to myself what just happened.
 
AKNick

AKNick

640cc Uber Pimp
Snoopy1 said:
It was purchase as an ARF. From prorc as I said before first flight lasted about 1 to 2 minutes. Pranged the plane built a new fuselage and reused the tail and wings, same proportions and measurements just a new fuselage. Well the same thing happened with it the second time both times standing on the flight line saying to myself what just happened.
Click to expand...

That's no good. Sorry to hear this. Almost sounds like it's drastically tail heavy being extremely pitch sensitive. My 15cc carbon cub manual CG was off (they made a amendment to it later), I took off, everything seemed great, pulled the stick and it was all over the place. Took everything I had to bring it back. So even a minor input it would act like you had rev expo.
Ironically I kept telling myself to trust the manual, and after I flew, I knew exactly what was up because my moral conscience told me to make the CG at the wings center of lift like I always do.
 
Snoopy1

Snoopy1

640cc Uber Pimp
AKNick said:
That's no good. Sorry to hear this. Almost sounds like it's drastically tail heavy being extremely pitch sensitive. My 15cc carbon cub manual CG was off (they made a amendment to it later), I took off, everything seemed great, pulled the stick and it was all over the place. Took everything I had to bring it back. So even a minor input it would act like you had rev expo.
Ironically I kept telling myself to trust the manual, and after I flew, I knew exactly what was up because my moral conscience told me to make the CG at the wings center of lift like I always do.
Click to expand...
I agree with some of your analysis and yes the CG was set to the manual. But then I have two questions why did head straight for the ground and when I pulled up the immediately Started to roll over onto its back. Let go the elevator then started head for the ground again then it was over.
I must gone gone that minute a hundred times since then trying to understand what I did or did not do that could have prevented what happened. I which it was just a stupid mistake that I did and it would ok don’t do that again
 
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