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Old 07-23-2021, 02:06 PM   #1 (permalink)
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Default OMP M2 Crash

Hi guys. I just recently bought my first heli, the OMP M2 V2 and today I took it out for the first flight. I had a crash that appears to have shattered the entire frame on the left side and possibly done even more damage that I have not found yet.


Everything was going great with the maiden for the first battery. I had no intention of taking it out of "normal" mode, but wanted to see the limitations in that mode, so I went full throttle up then then full throttle down. The second I did that I lost all power and it came crashing down. At first I had no idea what had just happened. I figured I had a short or something. After further investigation, it appears that this is normal for the heli to do this. I tested it on the ground. The moment you get the throttle lower than about 5%, it cuts all power and has a delay of about 2-3 seconds before it spools back up. So I guess that explains the crash, but I am left wondering if this is normal. If so, I really need to figure out a way to eliminate in the future. I do not think I can remember to always keep it above that throttle threshold while flying.



I will be contacting OMP as well to see what they think. In the mean time I guess I need to repair this thing. You guys have any suggestions on what i should look for in terms of hidden damage? This is crazy, I never thought I would be talking about this much repair after the first time out. ugh.


Thanks for any suggestion!
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Old 07-23-2021, 02:09 PM   #2 (permalink)
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Yeah. You have it set in normal mode. That's exactly what it does.

Check for bent main shaft and spindle shaft.

There is not much hidden damage that occurs in these helis as they are very simple.

Be glad you learned this lesson on a micro. Get to the 500 and up size and do this and you would have a totaled heli.

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Old 07-23-2021, 02:27 PM   #3 (permalink)
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Thanks thickfog. Will I be able to tell if the shafts are bent just by eyeballing them?


I am hoping to understand the idea behind this delay when coming off of zero throttle a little better. So it is programmed in these helis to have a long delay after having the throttle dropped to zero? Is it the same way with the throttle cut switch? If I hit the throttle cut switch in mid air am I doomed to crash? If so, how do people do auto-rotations? Bear with me, I am a fixed wing guy
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Old 07-23-2021, 03:02 PM   #4 (permalink)
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Quote:
Originally Posted by loppydog View Post
Thanks thickfog. Will I be able to tell if the shafts are bent just by eyeballing them?


I am hoping to understand the idea behind this delay when coming off of zero throttle a little better. So it is programmed in these helis to have a long delay after having the throttle dropped to zero? Is it the same way with the throttle cut switch? If I hit the throttle cut switch in mid air am I doomed to crash? If so, how do people do auto-rotations? Bear with me, I am a fixed wing guy
Auto rotate is done with the collective, you still need headspeed though, so if you dont have any, then it wont work, you can get headspeed depending on how fast the bird is falling, however you also need the height, I started by practicing landing without power, starting at a couple of feet off the floor, im up to about 8 foot off the floor, hitting the hold switch which kills the power, still with head speed, as the bird starts falling faster towards the groud, raise the thottle stick a little more which increases the collective too, you want it 50% stick or more as everything below that is negative pitch which will just push it faster to the floor, as long as you are in the positivce pitch range it will slow the desent for a gentle landing.

Something like this, last 15 or 20 seconds: https://www.facebook.com/715534584/v...7460054901016/

If you are just learning, first lean non collective hovers, where once you get her hovering in front of you (tail in) dont touch the throttle stick again, just keep it balanced using aileon and elevator, you'll soon learn where the dead spot is, use rudder to turn her sidesways on and same again, non collective hover side in, head in is the hardest to learn as everything is backwards so to speak.

Last edited by Jamin280672; 07-23-2021 at 03:17 PM..
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Old 07-23-2021, 03:36 PM   #5 (permalink)
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Remove one blade. You can spin the spindle shaft screw and watch the opposite grip and see if it wobbles.

For main shaft you can usually spool it up with no blades and watch the head and swash. They'll wobble if the main shaft is bent.

Or take both shafts out and roll them on a glass or granite surface, etc. You'll see the wobble if bent.

Spindle shaft check:

XK K110 Hurricane gone wrong into concrete. Still flew fine like this! (0 min 11 sec)


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Old 07-23-2021, 03:42 PM   #6 (permalink)
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Also your chances of doing auto rotations on this size heli is about zero percent.

I doubt many can pull one off. At least a true auto. Not what people mistakenly call an auto by cutting throttle a few feet up. That's just bleeding off blade speed and hoping to land.
Don't worry about autos for now.

Worry about setting the heli up correctly. Get rid of normal mode. It'll teach you bad habits is all. Your throttle should be controlled by a switch, not the collective stick.






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Old 07-23-2021, 04:00 PM   #7 (permalink)
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Thanks guys. I will try to figure out if I have any bent shafts. I am thinking its unlikely because it looked like I crashed skids first so the landing gear and frame took all the load.


I have no plans to learn auto rotation, I just thought I knew what they were and figured it would be impossible to do them with a delay like this. Clearly I needs to do some more research.


As far as taking it out of beginner mode. I tried on my first battery real quick, but realized I was not ready yet. Maybe the solution is to simply setup a mode identical to an idle up, but with stabilization? That way the head speed never goes to zero unless the throttle cut is hit?
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Old 07-23-2021, 04:49 PM   #8 (permalink)
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Quote:
Originally Posted by loppydog View Post
Thanks thickfog. Will I be able to tell if the shafts are bent just by eyeballing them?


I am hoping to understand the idea behind this delay when coming off of zero throttle a little better. So it is programmed in these helis to have a long delay after having the throttle dropped to zero? Is it the same way with the throttle cut switch? If I hit the throttle cut switch in mid air am I doomed to crash? If so, how do people do auto-rotations? Bear with me, I am a fixed wing guy
That is how ANY heli will behave if you hit zero throttle.

Helis have a slow spool function when you start the rotor to prevent them from spinning in circles on the ground. You reactivate that slow spool every time you touch zero no differently than if you were starting off with a new flight on the ground

Most use an idle up flat curve with no zero and simply use the throttle hold switch to start/stop the rotor for this very reason. It doesnt matter if you use TC or TH or drop the collective stick to bottom, she is going down and back into slow spool if you do anything that causes zero throttle even for a second.

There are special ESC or FBL modes to overcome this for autorotation practice where you need a fast spool up again in air if you decide to bail out, but as stated this is very small model and not really suited for autorotation's unless you are a very experienced pilot, so I suggest you put that out of your head for now and not overcomplicate things.

There just isnt enough mass/inertia in the blades on small models and they will come to a complete stop almost instantly without power. And you would need the slow spool back again anyway the next time you take off or its just going to spin around in circles on the ground as soon as you try and spool up
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Old 07-23-2021, 04:58 PM   #9 (permalink)
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Was your throttle curve 0, 25, 50,75,100? Set it to say 60 flat. Have hold mode on when powering up. Flip out of hold to fly.
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Old 07-23-2021, 05:44 PM   #10 (permalink)
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Thanks Xrayted for clarifying that. I wasn't sure if throttle cut switch and setting zero to the throttle curve were treated the same, now that makes sense. What still doesn't make sense is that anyone would recommend ever using a throttle curve starting at zero in any mode. That just seems like setting up for failure. Oh well, now I know. I will get this thing back up and running and keep practicing.


Jason671 - I set the radio from a youtube video. If I remember correctly the throttle curve for normal mode was 0 75 75 100. Or something like that.



Also, I was meaning to ask. While I am ordering replacement parts to fix this, do you recommend getting other spare parts while I am at it? Tail blades, main blade, ect? I want to make sure I am prepared with parts that break all the time.
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Old 07-23-2021, 08:44 PM   #11 (permalink)
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After looking into this crash a little further, it appears that the aluminum frame that the carbon frame attaches to is damaged as well. This looks to be a much larger repair than I originally thought.
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Old 07-23-2021, 09:01 PM   #12 (permalink)
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Quote:
Originally Posted by loppydog View Post
After looking into this crash a little further, it appears that the aluminum frame that the carbon frame attaches to is damaged as well. This looks to be a much larger repair than I originally thought.
Wow. That's an amazing crash buddy. Sorry.

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Old 07-23-2021, 09:08 PM   #13 (permalink)
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Yeah its kind of wild. It didn't seem like it even hit the ground that hard. Just kind of bounced a little. I will get all the parts coming, but am very nervous to take it apart down to that level. Guess I have no choice but to try.
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Old 07-24-2021, 05:12 AM   #14 (permalink)
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a flat curve of 70 or 75 and no zero at the beginning. reaching zero in normal mode made it go into slow start.

left stick is collective and rudder only. theres a few beginner threads here on how to set a heli up. but deff ditch the normal mode.
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Old 07-24-2021, 08:21 AM   #15 (permalink)
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Quote:
Originally Posted by loppydog View Post
Thanks Xrayted for clarifying that. I wasn't sure if throttle cut switch and setting zero to the throttle curve were treated the same, now that makes sense. What still doesn't make sense is that anyone would recommend ever using a throttle curve starting at zero in any mode. That just seems like setting up for failure. Oh well, now I know. I will get this thing back up and running and keep practicing.


Jason671 - I set the radio from a youtube video. If I remember correctly the throttle curve for normal mode was 0 75 75 100. Or something like that.



Also, I was meaning to ask. While I am ordering replacement parts to fix this, do you recommend getting other spare parts while I am at it? Tail blades, main blade, ect? I want to make sure I am prepared with parts that break all the time.
The above is an age old debate in any RC heli forum for years. Even experienced pilots have been bitten by this one by flipping inverted and forgetting they are in "normal" mode until the they reverse the collective stick and watch the model fall out of the sky. Normal mode makes no sense at all on an electric collective pitch model. Its a carry over from the early nitro only days.

Sucks you trashed your model so quickly. This is typically one of those situations where I would buy another fresh model and use the damaged one for whatever spares are left. It can sometimes be a real challenge to get a small model to ever fly correctly again if damaged bad enough as you constantly find little things wrong that you missed the first time, so its better to just start fresh. Especially if the repair cost is within reasonable range of what the entire kit will be
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Old 07-24-2021, 08:27 AM   #16 (permalink)
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What he said. This might turn into replacing this and that and that and then you find more damage. Order, wait again, replace and still have a vibration, etc.

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Old 07-24-2021, 09:16 AM   #17 (permalink)
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Thanks guys for the tips. I think I found all the obvious damage and I have the parts ordered to fix it. The cost of replacement parts are surprisingly inexpensive on this model, so it’s not really an issue with cost. I am hoping to be able to repair this without removing the upper half of the model.

It looks like it landed on the skids mostly nose first. This shattered the left carbon side frames. It also bent the two “tabs” on the motor mount. It took it out last night to see if it would still hover and it seems to hover with our issue. I didn’t notice any vibration or anything. I also set a flat throttle curve in all of my modes including normal mode. It should never crash in that way again.
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Old 07-24-2021, 09:24 AM   #18 (permalink)
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the metal motor mount plate can sometimes bend at the front where the carbon side frames attach. If the bend is minor you can just bend it straight again. If the blades hit the ground check carefully the feathering shaft and main shaft were not bent, even the most minor bend will cause vibrations which aren't obvious but which will cause the tail motor and/or tail ESC to overheat and potentially burn out. Just this weekend I repaired an M2 for a guy that had a crash and went on flying his heli with a slightly bent feathering shaft (unknown to him). 4 flights later the tail ESC burned out.

As the others have explained, this crash is caused by using 'Normal Mode' throttle. Personally I always advise never to use normal mode, just use all 'flat line' throttle curves then start and stop the motor using the throttle hold switch.. this is much safer.
Way too many people crash due to using normal mode. I liken it to having a 'special feature' on your car that makes the wheels fall off if you press the brake too hard
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Old 07-24-2021, 09:51 AM   #19 (permalink)
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Join this thread too. https://r.tapatalk.com/shareLink?url...&share_type=sf

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Old 07-24-2021, 09:59 AM   #20 (permalink)
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Also full assembly manual is here. It's pretty good.

https://ohiomodelplanes.com/products...xplore-version

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