Today was my maiden flight of a Showtime 50 w/ a .91 Saito. After 3 flights, we took off the cowl to adjust the needles. On restart, the nut came loose without me knowing it (yes, I should and will use a second lock nut from now on). When I revved it up on the bench, the prop suddenly flew off of the plane, the cone hit me in the leg (no problem), and the vibration/gyration pulled the engine/cowl off of the firewall.

Check out the last picture: I am standing where we found the prop! I was standing right where the photographer is now standing.

BTW, the maiden went well, landed a deadstick.<G> Love the plane, looking forward to getting her back in the air.

Your lucky it flew off to 3 o'clock and not 9 o'clock. I'd add to a lock nut that you make a practice of moving behind the plane before you run the engine up or even take the glow starter off.

I'm a bit paranoid of this situation and spend as little time as needed in front or in the arch of the prop.

I've noticed a lot of firewalls coming off lately. There must be a shortage of epoxy in China.

We recently had a few come off at our club too. I just don't think people realize/care about the forces acting on these models.

Agreed, very lucky, and my father-in-law was there, and happened to comment that he never stands in front of a running engine.

That may very well be true. But if you consider the force of an asymmetrically spinning prop at 9k rpm... I wasn't too surprised at the outcome.

Was your engine running backwards? How is it that the prop flung to the left, without striking the bench, unless it was running backwards?

Thats assuming that it came cleanly off the shaft. Judging by the fact that it didn't shoot off to the right and now the engine has removed itself from the firewall i think its safe to say that the prop came off the end at an angle. Who knows where it could have gone! [X(]

The engine was NOT running backwards, and, interestingly, the cone remained screwed together! The prop flung out through one of the side holes in the cone. The cone hit me in the leg and fell to the ground.

The prop must have worked its way off of the end of the shaft, and within milliseconds, spun out of control, flinging off at around the 3 to 2 o'clock position, just missing the bench. It may have actually struck the bench since I heard some banging. We'll never know. I checked the bench and found no obvious marks, and the prop looked pretty much unharmed.javascript:void(opener.AddText('[sm\=71_71.gif]',''));self.focus();

Very, very dangerous, to be sure.

Like my friend said, if that prop would have pierced my heart, just as I was about to pass out, my final thoughts on this planet would be "I was just killed by my toy plane."

Lucky guy. I always use two nuts AND blue threadlock..... Just to be sure

Ian F.

Also you may want to add some lite ply to the landing gear mounting area. I had the gear rip off of mine on laning and poked a hole in each wing and did some fuse damage. Upon inspection after the incident, the area H9 uses to mount the gear is VERY weak.

Actually all these ARFs from wherever across the Pacific have a structural problem. I have personally seen a number of firewalls let go, especially those with top or a bit more engine than recommended. Even seen a thumb and finger also depart the owner, due to a restart after a hard nose landing and no significant check of the front end. G-38.

I really reinforce all my firewalls even my built models to the point of aluminum straps bolted around the corners as a Safety precaution, especially on those engines exceeding 1 cu.ins. Others get significant reinforcement.

In addition there are a number of ARF models that have very poor structural engineering around the tail-feathers and the LG mountings. Your life!

Like my friend said, if that prop would have pierced my heart, just as I was about to pass out, my final thoughts on this planet would be "I was just killed by my toy plane."

ROFL!!!

Sorry Scrappycat, I just couldn't stop laughing over this comment.
I had some final thoughts at my own "going away party" about 15 years ago.....the ER staff came through, I actually saw my life flash before my eyes! I guess we both have an angel watching over us...

u r lucky

I started my ys-160dz with a zinger wooden prop and it blew apart and hit the house, i always reglue all joint including the fire wall, what scares me is this happens all the time and i see so many children with there dads running there engines up with kids standing right beside the prop, people just do not think, it is common knowledge to use a lock nut, i have also seen so many plastic spinners blow up and one guy told me his was balanced, i asked him if he used a torque screw driver as it is impossible to balance a plastic, i also use the hyde soft mount on all of my planes that saves me from buying a new servo or loosing a plane because of all the vibration, you can hear it when they take off and when they are flying, try one and you will never go back to a hard mount.

Yea they must be getting it mixed up with the toothpaste.