My brand new take apart Ringmaster was lost this morning on it's second flight.  The conditions for the crash are truly one for the books, bizarre!  I had just completed the full pattern on the plane was doing a couple of outside loops to unwind the lines from the triangles.   I started climbing out of the second loop when the motor slowed down to signal end of flight.  The lines went a bit slack but nothing I couldn't recover from, but then the motor came back up to landing RPM.  The torque from the motor snap rolled the plane in at me and the plane dropped into a spin and hit the ground on the outboard wing.   


I not only have never heard of such an event like this, but for the first few minutes I could not even explain what I had just seen.  Fortunately my flying buddy Larry Renger was there and saw the whole thing.  He is the genuine rocket scientist from MIT, the first thing he asked me was what did I see from where I was.  I said it looked like the plane did a quick roll toward me and spun in just after the timer signaled end of flight.  He smiled and said "OK that's exactly what I saw.".  He then explained that the plane was flying up near vertical as it was slowed down from the motor dip.  Just as it was approaching stall speed the motor revved back up to finish the landing, a perfect combination for the torque to roll the plane.  I tell you I have never seen anything like it, in fact I am not sure it can happen on a gas plane.   Larry and I talked about this for several minutes and we could not come up with any other explanation that fit what we had just seen.

Heck of a way to lose a new plane, if I had just flown out the laps at the end I would still have the plane.  I'm a little sick over this.   
Andy

Bummer Andy,

Although I have one of Keith's KR timers I have not used it yet (as I gaze out the window at the snow coming down). The Will Hubin timers that I have been using just give a slight drop in the RPM and no where near a full stop. Therefore, the winding back up to flight RPM does not seem to be that great. Granted I have not had one do the end of time approaching signal while in a vertical climb. Actually, I usually use a talking timer which counts down the last minute at ten second intervals and the old ten, nine, eight etc, countdown for the last ten seconds. Al Hahn put me on to that years ago -- it has clip that hangs it onto my shirt pocket. That little timer would have save you a Ringmaster. Sigh!!

Sounds like your take apart was a good flier too. 

I can't for sure how far down the KR timer goes but it is not a full stop at all.  It's just a dip for a couple of seconds and then back up to flight power.  The problem this time is where the dip happen and where the power came back on.  It's been a while since I flew on a Hubin timer, but I seem to remember it had a dip as well.  In my case the power dipped just when the plane needed it most and then came back on.  As I often say the laws of physics are self enforcing.  We need to know when the flight is about to end and the dip in power seems to be the standard for the timers I have seen.  Such is life.
Andy

Good question Chris, I just checked the prop to be sure.  It was set up for Tractor prop which made the torque roll left and in at me.  Had I put a pusher prop on the plane this might not have happend.  The roll would have been away from me and the line tention might have kept it from snapping over.  I need to give that some thought.  As a rule I don't normally fly with tractor props, but I was given this one to try out. 
Andy

Andrew

Sad to lose any good ship.  But Crist hit it on the head with the Prop type.  Not really sure that the ship could have been saved "fully" with either prop, but the tractor prop sealed your fate. The KR timer gives 3 seconds of motor retard then back to the chosen RPM.....not to be blamed for the crash
 
You may want to look  into a timer/timing device to have with you when flying. These work very well and are easy to set up and use.  The item I've pictured is one brand, I've used this one for 9 years plus....just change the batteries every year or so.   This has saved a couple of planes so far.

Regards
Dave
ama41041

Andy,
Sorry about the ship going in, hopefully you can repair it (that's the good thing about electric - no oil). I setup my systems without the power dip warning. Originally I used it, but got caught coming out of the last loop on the clover one time and had to pull out short of the stem. I like to set the timer up to give me 7 - 10 laps after the last maneuver. This varies with the pattern (OTS vs PA) and line length/lap time.

I never undo the loops - seen to many top fliers lose ships with the engine quiting early. Some guys put one outside turn in before takeoff so there is only one turn at the end. . I just keep the lines clean. Let us know if you get her back together.

Best,          DennisT

There was some minor fuselage damage.  The wing is toast since it hit hard, straight on the wingtip. But since the wing is removable, a new wing kit could put that baby back in the air!

is that the same effect that causes crashes is real ww2 aircraft when they(pilots) decide to go around and add too much power to quickly ?

Andy:

I keep telling you that "Take-Apart" does not meant that you use the ground as a tool!(lol)

Sorry about the ding to the Ringmaster. From Larry's post it appears that the fuselage survived (probably all of the lamination which adds in enormous strength without weight). I look forward to seeing the results on Friday. By the way, I have a new Take-Apart Ringmaster for you. I just know how much you love building!!!

Eric Rule