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unexpected acceleration after landing?


Well-Known Member
Jan 18, 2017
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Albany, CA
On just a slightly hard landing, the Mach 25 motors unexpectedly accelerate hard, causing it shoot up. Then it lands hard again and the cycle continues. So, I have to cut the motors to stop it.
Just by way of explaining the issue (and maybe not the safest thing to do) the same thing happens if I pick up the quad while it's just idling at the lowest throttle position: the motors accelerate hard when the quad is picked up just a few inches off the ground.
Please tell me what's going on? And how to fix the issue?
It's your flight controller trying to correct the drone position. Like I've said before I'm not familiar with the Mach but is there an acro mode? And do your props spool up when you flip switch?
I'm in acro mode. The props take about 1 second to reach idling rpm, with occasional hesitation at the LF and RR. There's also a little chirp at start up (could be an indicator/warning beep) Thanks.
I'm in acro mode. The props take about 1 second to reach idling rpm, with occasional hesitation at the LF and RR. There's also a little chirp at start up (could be an indicator/warning beep) Thanks.

Crap sorry I meant air mode
Are you saying it does that ever since the hard landing? Like when you flip the switch to activate it? The motors accelerate on there own?
Flight mode is 2.
With the quad at low throttle and (what I think is) standard setup, if I pick it up a few inches (but don't touch any controls on the DX6e) the motors accelerate. When I set it back down, they go back to idle. The Mach 25 (that I lost) did the same thing. This replacement Mach 25 hasn't had any major crash landings. The hard landings I'm talking about are equivalent to dropping the quad from less that a foot. Thanks.
Well if I'm understanding correctly it seems like the prop wash is just upsetting the Fc. If it doesn't do it at a higher altidude it probably has something to do with the mode your in. I just looked at the specs on it and it doesn't appear to have an air mode unless it's build in to a flight mode. Look up on YouTube what it looks like trying to land with air mode on and see if that looks like what it's doing. Do you have you end points set? You might have your throttle set below 1000.
Thanks for digging into that. Prop wash sounds right, but the throttle accelerating when I pick up the quad seems odd. And the throttle accelerates when the quad comes down a little too hard and then it bounces up. Then with each progressive bounce it goes higher and then bounces higher still. If I don't hit the throttle cut switch soon enough, the Mach crashes into a wall. Seems like it's misreading the load on the props or something. I dunno.
I looked at several YouTubes of air mode flight and the only one I found that showed a landing looked pretty normal.
Sorry, I couldn't find throttle end points or any numbers other than percentages. I played around with throttle trim a little on the DX and that may have helped but only slightly.
In any case I'm having fun learning how to control the Mach just by running it around in a large room with a wood floor. Too much rain here, and I'm pretty wary of losing this replacement quad outside.
If you can post a video I can probably tell you for sure but that is pretty normal. I'm pretty sure from what you said it's the flight controller trying to correct the aircraft. All drones will do that if you pick them up while armed. Prop wash would make it drop a few feet but not accelerate unless your in a self leveling mode.
Thanks, bud. I'll shoot a video when it dries out around here and I can go outside. For now, before I get a simulator, I'm trying to practice indoors, and the bouncing / acceleration is sending me into the wall more than I'd like.
I see in the Mach 25 manual: "In agility mode, the system does not self level. Use rates and expo to tune the performance according to your flying style."
I just tried agility mode and that's a little quicker responding than my brain can handle..

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