Hitting Asphalt Damage?

[Kafin Noe’man]

Hi all, this morning I tried to fly my Vector by myself using the “goal posts” stooge. By using this stooge, it’s very likely for the plane to have a slight “bump” upon the release due to the position of its tail wheel to be on the top of the stooge platform. (Please see the attached sketch)



And today, I wasn’t lucky, the “bump” had caused the nose of my Vector to be pointing down and yes, the prop was hitting the asphalt and it got cut. Other than the prop cut, how bad could the damage be? Especially to the airframe. Any similar experience?


Best,
Kafin

[Gerald Arana]

Depends on the prop and how badly it hit the ground. Wood; probably no damage to the engine. Plastic or glass; Could damage the engine but probably didn't.

Run the engine and if it vibrates more that it did before it hit the ground it probably bent/distorted the crank.

Good luck, Jerry

[Ken Culbertson]

Did the bump stop the engine?  Prop strikes on takeoff are quite common, especially with competition grade ships where the clearance may be as low as 1/2" (don't try that at home, 1" minimum).  If the motor keeps running and is not vibrating wildly you have probably just turned a 11" prop to a 10 3/4". Wood props tend to split but "plastic" tend to simply grind off the tip.  If there is any damage to the airframe I would be surprised unless it split the prop and kept running in the air.  Look for vibration cracks at the wing LE and TE. 

If you have a clearance issue drop down 1" in prop size and go to a 3 blade AND for your own piece of mind GET A PULL PIN STOOGE.  I have only used the flapper type once.  Threw it out the next day.  Primary reason is that, unless you have tricycle gear, you have to take off differently and you don't want that to become how you practice.  The take-off and landing are the most practiced and most ignored maneuvers and they count nearly the same as inverted flight or the outside loops.  If you ever fly AMA rules they are the same as the square 8 (which is nuts IMHO)!  They are your "free points".  If your goal is competition, don't learn to do them wrong and pretend *every one* was at the world F2B finals, even on trim flights.
Ken

[Ty Marcucci]

Once I had a prop strike so hard, the model pivoted on the lines and snapped the rear half of the fuselage in half.   Another time a prop strike caused the wood prop to shatter in a thousand splinters and cut through the LE, main spar and TE...   Some days you wish you stayed home.

[Colin McRae]

I use a Brodak pull-pin stooge. I never liked the cable that came w/ the stooge that attaches to the model. A bit of added weight on a model and it flops around during flight.

I have been using this method and it has worked well for me so far. Insignificant added weight on the model and not that unsightly. I secured an eye screw to the tail of the model. Then I use a short piece of 65# Spectra (maybe 18" long as needed) to secure the model to the stooge. Same secure Spectra knots as I use on my flying lines.

The eye screw is epoxied to a 1/4" wood dowel. Then the dowel is epoxied to the model so the screw eye is flush w/ the model surface. See a few pics.

There will naturally be some wear and tear on the Spectra, so I inspect the line often. Have not noticed any wear per se. But since Spectra is cheap, I made up a few lines for the stooge and replace w/ a new one every so often as a safety factor. No failures to date and the system has worked well for me.

The model shown as an example is on my Brodak P40 ARF.

[Ty Marcucci]

I too have a stooge like that, only with a tail wheel cut out so no bump..Make a grove for the tail wheel, should cure the bump problem.

[Peter in Fairfax, VA]

Unlikely you bent the crank.  If you did, you can likely see the "runout" by carefully observing the crankshaft while rotating it.

[John Carrodus]

Kafin.
Did the engine stop or did you take off and fly?
Sombody suggested put on a new prop and rotate to check for a bent crank. I very much doubt you did any damage other than smash the prop , and vibrate the ship like heck if you actually flew. In which case check all controls and glue joints for stress cracks and get her back n the air. I hate the hard stuff and prefer the green stuff every time. Especially in the winter, the ground is soft and it's a good time to crash or bore holes for fencing.

[Martin Quartim]

sorry to hear about this problem. The APC 10.5x4.5 has a thin blade from the middle on, so  I doubt there was any damage, but check everything and re-tight any bolts, nuts, and screws.

 Before flying next time, run the engine for a minute or two and move the airplane around to make sure all is sound.

If necessary, you can quickly shut down the engine putting the nose down at 90o, to uncover the fuel pick up. Never done it, but I heard that the fastest way to shut down the engine is to pinch the exhaust deflector, I guess it would be the quickest way to shut down the engine if necessary but it may burn your fingers


Martin

[Larry Fruits]

 Do as Ty suggests and cut a slot in your stooge plate for the tail wheel. I have been using this type of stooge for over 15 years with absolutely no problems at all. Use a heavy, (65 pound plus), braided fishing line, (Spectra), for your stooge release line since it has very little stretch.

 Blessings;
   Larry

[Motorman]

A prop strike can damage anything in the nose section connected with the motor mount. Check for cracks around the fuselage/leading edge area and anywhere you can see inside the cowling. If the prop broke unevenly and continued to fly with vibration, the airframe could be cracked anywhere. Check your wing root and fuselage behind the wing. If you just buzzed the prop a little and kept going, chances are it's just fine but give it a pull test.

MM