JTM 90mm Viperjet by UsaRcJets - Page 56 - RC Groups
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Feb 26, 2013, 03:07 PM
Just an Earth bound misfit - I
vanderbrander's Avatar
Thanks for that. Might give it a try too
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Feb 27, 2013, 07:58 AM
Roll with the changes...
RibarSRQ's Avatar
Lost my bird this past weekend for no apparent reason. Still trying to figure it all out. Is it possible that a Spektrum DX8 / AR8000 combination would have any problems with the small amount of CF in the Viper combined with the Stumax CF? I know there is a bit of CF at the wing roots and I think the fan hatch is covered in it.

Full story at EDFDan.com

Let me know your thoughts and thanks.

Dan
Feb 27, 2013, 08:36 AM
2018 EDF Jet Jam June 14-17
Robert Belluomini's Avatar
Very sorry to hear this. I hope you can get to the route of the problem.
Read the story it sound like the battery shifted
Last edited by Robert Belluomini; Feb 27, 2013 at 08:44 AM.
Feb 27, 2013, 08:38 AM
Registered User
STEVEAIR2's Avatar
Thats just the pits.
I hope you find the cause.
Cheers
Steve
Feb 27, 2013, 10:49 AM
Do it Right, the first time!
CoolerByTheLake's Avatar
Vanessa c.g. Rig: How to.

http://www.rcuniverse.com/forum/m_708060/tm.htm
Last edited by CoolerByTheLake; Feb 28, 2013 at 07:49 PM.
Feb 27, 2013, 12:16 PM
Formerly "Heli Copter"
Jetsom's Avatar
Quote:
Originally Posted by RibarSRQ
Lost my bird this past weekend for no apparent reason. Still trying to figure it all out. Is it possible that a Spektrum DX8 / AR8000 combination would have any problems with the small amount of CF in the Viper combined with the Stumax CF? I know there is a bit of CF at the wing roots and I think the fan hatch is covered in it.

Full story at EDFDan.com

Let me know your thoughts and thanks.

Dan
I have had a Spektrum Tx/Rx lock me out using a reversing Y. Spektrum has a warning about electronic Y's plugged into their receivers.

http://www.spektrumrc.com/Experience...Practices.aspx
Feb 27, 2013, 12:35 PM
Just an Earth bound misfit - I
vanderbrander's Avatar
I'm so sorry to hear of your loss. I had a spectrum Dx8 last year that locked out in my 70mm viper causing me to ditch in the water. Thankfully it floated and the damage wasn't too bad but it's sickening when it happens.

After several other lockout events with the same tx but different rx, I sent the whole thing back to Horizon. To their credit, they update the tx software, replaced both my 7 channels with brand new DSMX rx, bench checked my AR8000 and shipped it all back for free.

You Couldnt complain about the customer service but my biggest issue was they couldn't find the root cause of the problem. That plus all the issue so many others had with that particular radio, gave me zero confidence.

I now fly a Hitec aurora 9 with full confidence and have been very happy since.

I'm not bashing spectrum. Some guys swear by them and have no issues. I'm just relating my personal experience, which sound similar to your.

Once again, so sorry.
Feb 27, 2013, 04:53 PM
Roll with the changes...
RibarSRQ's Avatar
My oldest son is a Citation pilot. Here's what he had to say:

How slow were you in the turn? I didn't see it but my only guess would be you skidded the turn and stalled the right tip.... BIG problem in aviation. Main reason for aviation crashes after fuel starvation.


It is very possible that he's right with that whisper quiet stumax....I am sending the DX8 back to HH for them to check it out before I use it again. I use the same TX for three other airplanes with no problems at all.
Feb 28, 2013, 09:24 AM
Roll with the changes...
RibarSRQ's Avatar
Guys -- Here's a short clip from 2 seconds before I put it in the dirt. Take a look and tell me if you think I might have NOT had enough energy. Don't hold back... let me have it.

Viper Crash Theory. Stall, Spin, Crash? (1 min 10 sec)


Thanks!
Dan
Feb 28, 2013, 01:09 PM
Just an Earth bound misfit - I
vanderbrander's Avatar
Doesnt look like you were going too slow, no unusual high attitude, or tight turn.

however i did notice It seemed to leap off the ground on the takeoff and climbed out very steeply. Was the cg too far back for the 2nd flight? Did you secure the batt? Did it feel unusually touchy? I'd be betting the batt shifted but its conjecture from a very short video. Can you recount your steps and be absolutely certain you secured the batt?

Only other explanation is this. If you did have a rx lockout (like I did) one thing I found with my ar8000 during post crash analysis was the controls would twitch during the reboot (which took about 1.5sec). If that's the case it might explain the sudden snap, lack of control, then inexplicable recovery before ( perhaps) a second reboot??

Try it on the bench. Set up some servos and simulate a reboot by disconnecting the battery then quickly reconnecting. See what happens.

Again it's pure conjecture and I hope you get to the bottom of it
Feb 28, 2013, 01:43 PM
Roll with the changes...
RibarSRQ's Avatar
Vander -- From the first flight, I was losing so much lift from the GoPro that I still had a lot of up elevator trim. since I wasn't too sure about the goPro as the cause I decided to correct it in the air. Ultimately the elevator trim was neutral.

Regarding the batteries, in the wreckage the battery casings (the plastic covering) was still attached to the floor. The guy with me even stated "And they say velcro doesn't work"... so they still attached.

Thanks for the thoughts. It seems like a very exciting and normal flight up to the point of the crash.

Peace.
Feb 28, 2013, 02:12 PM
Just an Earth bound misfit - I
vanderbrander's Avatar
Good. At least you've ruled out cg.

Try bench testing your radio. You may be surprised how it reacts to a reboot.
Feb 28, 2013, 02:34 PM
3DHOG
jcdfrd's Avatar
are you using any servo reversing "Y" servo leads in you setup? like for flaps or elev
also did you check at the crash site for flashing light on the reciever, provided the reciever pack was not ejected
Feb 28, 2013, 03:49 PM
Roll with the changes...
RibarSRQ's Avatar
Had a great talk with BillyD this afternoon. I'll let him expand on what I'm about to say. Sounds a lot like I had too much throw on the elevator.

Everything was set as Billy suggested on my low rates -- elevator was at 10mm each way. I checked and rechecked this so I know it was right. BUT, I had thrown it on high rates to get enough movement out of the nose wheel to get it lined up for take off and probably forgot to put it back to low rates (was a little excited). So you can see me pop off the runway and pull hard on the turn.

Bottom line? My problem. I screwed up.

So big warning here -- listen to BillyD and the guys who are in the air when setting your throws. Hopefully my pile of composites and electronics will help someone else not end up in the same spot.

My beautiful wife exclaimed "at least it was a SPECTACULAR crash"....

Peace.
Feb 28, 2013, 03:51 PM
Registered User
icicles's Avatar
What you did flying wise looked perfectly fine to me. Not too slow etc etc.
What is you failsafe set to. See many guys with Spectrum (not picking on them ) not setting their failsafe after a model is set up.A mate here has an F5B glider that had a weird failsafe which if it had activated would have been a very unusual crash based on the servo positions if it had gone into failsafe

Chris


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