rj lemay

My Feedback: (8)

Hi Guys,
I was at our field yesterday to maiden my newly completed R2. I think I had about 600 hrs into the build. The engine is a Saito f84 R3. Raido is JR Xg11 with 8411 HV servos all around. Balance was perfect. Well we started up, taxied out, and was ready to go. Hit the throttle, she did whatshe was supposed to, right after the tail started to fly, I pulled a little elev. and off the ground it went! Perfectly. Not 2 seconds later the plane violently rolled inverted, about 8' off the ground, and dropped into the ground, instantly destroying it, The engine is ok, except for a bent pushrod, raido worked again, after i walked over to it, but the plane was gone. Now this is the third crash I've had with this raido system and it's not even a year old. My question is is it really critical to absolutly seperate reciever and battery from ignition battery and its switch? There was probably 10" between the two inside the fuse, which was about all I could manage, and the ignition module way up, mounted to the backside of the fire wall..Thanks for any input.
Really Bummed in Ct.
rj lemay

jeffo

My Feedback: (68)

Sorry about your bird,do you think it torque rolled in? I heard you have to run a 6 volt system in JR,or you will have problems.I'm pulling at straws,personally,it sounds like you have an intermittent radio problem.My buddy had the same problem,ditched his radio,and the problem went away.jeffo

All Day Dan

My Feedback: (5)

Where was your throttle servo? Did you use a metal throttle pushrod? What kind of kill switch did you use? Were any of the ignition wires near the receiver wires. Did you do a low power range check with the engine running? Is that the JR with the remote receivers or the one with the two flexible antennas coming out of the receiver? Was the ignition pack at the firewall? Where was the receiver battery pack? Dan.

rj lemay

My Feedback: (8)

hey Dan..
Yes it was a flex throttle pushrod in a plastic tube it was the typical sullivan metal wire. The throttle servo was on two wood rails centered in the bottom hatch, Also on those rails were the reciever, the flight battery pack on one side, on the other side was the ignition battery pack, and a servo operated heavy duty jr switch used as the kill switch. There was probably 8" between the two. I did not do a low power range check with the engine running. the jr reciever had the two flex antennas coming out, and a remote antenna on a 2 ft. lead going to the rear of the fuse. The ignition pack was mounted directly, on foam, to the back of the firewall. Thanks for the input, Bob oh boy you know what? the throttle pushrod was not the one i described, it was a bare metal rod running from those rails, through the firewall where all three ignition wires also ran through. The igintion wires were installed with the included plastic shielding around them.

Instructor

My Feedback: (16)

Hi lemay,

I wouldn't use a receiver from a recent crash unless you have flown it in a plane that you didn't care if it went in. I'm not familiar with this JR radio, is it a 2.4 GIG radio?
Seeing that you have had three crashes from this setup, it could be the switch or the receiver. Also, I never rotate after the tail has risen off the ground until I
run at least another 40 feet. There isn't enough airspeed for the ailerons to function properly and torque will cause the plane to snap over.

Larry/Instructor

All Day Dan

My Feedback: (5)

rj, I don’t know what caused you to crash and we will never know. A metal throttle pushrod is asking for trouble. It acts like an antenna and will pick up any radio frequency interference near it. This includes the RFI from the motor, ignition module and especially wires running parallel to it like you described. That RFI couples right into the servo and then right into the receiver through the servo wires. The problem is that it does not happen all the time and a lot of guys are getting away with it. Sorry for the lecture but I hope this helps. Dan.

jeffo

My Feedback: (68)

RJ,did it torque to the left? The R2 has very little vertical stabilizer,and you have to contend with aileron reversal at low speeds with the R2.I know it's a tough pill to swallow,but it probably torqued in.jeffo
-the bottom line is you'll never know

rj lemay

My Feedback: (8)

thanks guys,
i dont think it torque rolled in jeff, only because it rolled over so suddendly after a great take off it was as if the ailerons pegged themselves to the left. i tried to counter, but had nothing. it really did feel like the raido was experiencing interferance. im usually spot on to correct a dropped wing or whatever on a takeoff, i recently maidened my bvm electra which dropped to the left on take off, and was able to pull it out no problem. im really thinking that what Dan is saying is right. as i took out the saito manual and was reading, it does stress that you need to not only isolate all raido from ignition electronics, that any metal pushrods is strongly discouraged. in hindsight, there are many thing i would have done differently inside that plane. ill be able to also, because im going to build it again....and no I never use a crashed reciever either, Larry sometimes I wont even use the same servos... its just not worth it!! Thanks for all the input, Guys. Bob

JeffH

My Feedback: (43)

I would buy a used junker airplane and fly the mess out of it trying to duplicate the issue. At the very least, send the radio back to JR and have them check everything out. You could have a bad solder joint on board in the Tx that opens and closes whenever it feels like it, temp vibration, you squeezing the radio in a tense moment etc etc

Jennifer Curtis

My guess is that once the plane got
out of ground effect, the wing stalled.
I've seen this happen to a number of
fully detailed scale planes (ones with
all the extra weight of the scale details
and paint, etc).

Some of the pilots I've seen do this are
scale builders who spend tons of time building
and not so much flying, so they are rusty when
they have a new plane ready. Others were actively
flying other planes with less scale characteristics
and weight, and weren't prepared for the
characteristics the new plane exhibited.

The pilots always had no idea what went wrong,
but to the experienced scale pilots, it was always
obvious.

I don't know where you fit in these categories.
I'm just offering my observations for you to
consider.

Jenny

rj lemay

My Feedback: (8)

Thanks Jenny
That's a very close description of exactly how I fit into this hobby. I am 50 and have been building and flying since I was 13. I'd much rather build then to buy an arf although I do own a few. This gee bee was 26 lbs l fueled up ready to go... Maybe what you're saying is right... That type of airplane is a lot different than 40 size glow airplanes. I did own a Paige fifth scale gee bee years ago and never had anything like this happen. Great flyer never crashed. Oh well.... My next one will have many things different that I wish I had done one this is one. Oh yeah I do have 4 other planes on that system that have never exhibited any problems like this . Thanks again Bob