What the Heck Wednesday - Radical Rafale Roll

This week on What the Heck Wednesday we have a maiden flight of a Rafale EDF Jet with a wild un-commanded roll shortly after take off.

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That's Not Supposed to Happen!

This week on What the Heck Wednesday we have a maiden flight of a Rafale EDF Jet. It sounds and looks good on the runway and tracks nice and straight. The take off is abrupt, but what happens next is where things go pear shaped. It immediately rolls left all on its own and the pilot pulls power and manages to set it back down on the runway with a thud, but in one piece at least. After cleaning out his pants, the pilot must of asked himself, what the heck happened? I'll post that same question to you guys. What do you think caused that unintentional roll? Man was that guy lucky that plane completed the roll and stopped!

If you have a video of a weird or entertaining crash and would like to be featured on What the Heck Wednesday, please send me a PM with your submission.

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Jul 14, 2021, 08:02 AM
R_G
R_G
UFO Driver
R_G's Avatar
My guess...revered ailerons! On takeoff it banks to the left and to correct the pilot adds right stick, but being reversed it continues with the roll to the left. He's lucky it landed as well as it did.

Ralph
Jul 14, 2021, 08:50 AM
Classic jets rule
AIR SALLY's Avatar
I agree with Ralph
Jul 14, 2021, 09:57 AM
I'd rather be Flying
davecee's Avatar
Nope. The video quality makes it hard to see but here's my opinion.
Take off roll starts with both elevons neutral. Then the left elevon deflects upward while the right elevon appears to stay neutral. The left elevon appears to remain deflected upward through out most of the short hop. Right elevon servo failure or improper mixing of the elevon servos.

This is a direct quote from the pilot in the comment section of the video. I did not find this quote until I had already formed my opinion.

Quote:
wrong about the reversed ailerons. This was the result of an elevator up command to rotate, that was not communicated to the right wing. You can clearly see that only the left wing elevons responded when I pulled the stick. Probably would not have lifted off if not for the canards raising the nose as my battery was towards the nose heavy side. The instant the gear was free of the ground she rolled left, not axialy as there was no right wing roll, but not a bad roll either. As she came upright I killed both the throttle and the elevator. With the left wing centered again she straightened out. Maybe a bit of power should have been left in. Might not of fallen so hard. But at the time I just wanted to get her down.
I've added a screen shot of the left elevon deflected upward and the right elevon at a neutral position during the roll out.
Last edited by davecee; Jul 14, 2021 at 02:31 PM. Reason: sp
Jul 14, 2021, 12:10 PM
Registered User
SwampFlier's Avatar
Scary ... scary moment...
Jul 15, 2021, 04:58 PM
Scott
Pylonracr's Avatar
That makes it the product of a poor preflight inspection.

Scott
Jul 16, 2021, 10:34 AM
Fire Marshall Bill
Actually not. This was carefully gone over by myself and 3 other experienced guys prior to the flight.
Jul 16, 2021, 12:43 PM
Intermediate Multi
Trisquire's Avatar
Quote:
Originally Posted by Elmo Te
Actually not. This was carefully gone over by myself and 3 other experienced guys prior to the flight.
Did you ever determine the culprit? Loose servo connector?
Jul 16, 2021, 06:23 PM
jean-claude Terrettaz
bidule's Avatar
on Delta mix its impossible to take off if the control are reversed ..the jet will not lift off...bizarre
Jul 16, 2021, 10:02 PM
yank and bank!!
Incidentally, regardless of the plane's willingness to leave the ground, that was also a poor place to do a takeoff also....
Jul 17, 2021, 12:11 AM
Fire Marshall Bill
Really? Based on what? This is an AMA club field seeing a constant flow of takeoffs and landings every Friday and Sunday mornings for 15 years or more.

Elmo Te
Jul 17, 2021, 12:21 AM
Fire Marshall Bill
Trisquire

No, still can't get it to repeat. Very weird. The wing connectors are solid. I did replace the AR8000 with a 637T tho it is not possible that the Rx was the culprit. I just had all the wiring out and wanted to move the Rx to the nose and minimize the wire running back to the mixer box. It was easy to get all the extensions hidden under the battery floor. I have been running it around the street at 1/3-1/2 throttle with elevator inputs to see if it will repeat. So far, no.
Sunday I will run it up to full speed with the canards off and a heavy battery up front on minimum rates (so it wont rotate) while I have some club members watch/video it again to see if the elevator command gets both elevons to respond at full power/speed/vibration. If it still doesn't repeat, I may be obliged to retry the maiden. Or wait until HH finds a replacement mixer box for me,,,,,

Elmo Te


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