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Old 01-05-2012, 02:19 AM   #1
360Wings
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Default Maiden GT5 - Crash diagnosis

Didnt go to plan.. Spooled up, put it in a hover for 2-3 secs, then it "rolled" to the right, boom strike and down she went..

Im pretty sure a link failed and it wasnt a setup issue. My initial reaction was perhaps the gain was wrong, as it was more of a rocking motion left, then right rather than a roll. If you were to drop a coin on a table they will roll around their circumference before laying flat.

If it was the gain too high Im assuming it would have been oscillating during spool up and after putting the heli into a hover??

Does it sound like a link failure or did I screw something up in the setup?

(Fortunately the damage is minimal as i was only 3-4m in the air... blades, boom, main shaft, boom supports..)
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Old 01-05-2012, 08:01 AM   #2
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Have a look at the total gain on the display, if it is black numbers on a white background then that is the problem!
I found that if it is in rate mode it is like balancing on a ball if your setup is on the wild side, it really is quite a hand full.
So if it is black numbers on white you will have to work out how reverse it to white numbers on black. It may be as simple as reversing the servo on the channel that you have assigned to control total gain or switching from NORMAL to T-LOCK
It's not really rate mode on the swash so much as decay mode so it goes undetected on the bench!
If it is not in rate/decay mode then it could well be a ball link or severe vibration!
Is it on a vision?
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Old 01-05-2012, 08:38 AM   #3
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Quote:
Originally Posted by NitroAl View Post
Have a look at the total gain on the display, if it is black numbers on a white background then that is the problem!
I found that if it is in rate mode it is like balancing on a ball if your setup is on the wild side, it really is quite a hand full.
So if it is black numbers on white you will have to work out how reverse it to white numbers on black. It may be as simple as reversing the servo on the channel that you have assigned to control total gain or switching from NORMAL to T-LOCK
It's not really rate mode on the swash so much as decay mode so it goes undetected on the bench!
If it is not in rate/decay mode then it could well be a ball link or severe vibration!
Is it on a vision?
G-T5 is still in same mode, no rate/heading hold switch. "Balancing on a ball" = incorrect P/I ratio, propably low I.
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Old 01-05-2012, 08:45 AM   #4
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Quote:
Originally Posted by 360Wings View Post
Didnt go to plan.. Spooled up, put it in a hover for 2-3 secs, then it "rolled" to the right, boom strike and down she went..

Im pretty sure a link failed and it wasnt a setup issue. My initial reaction was perhaps the gain was wrong, as it was more of a rocking motion left, then right rather than a roll. If you were to drop a coin on a table they will roll around their circumference before laying flat.

If it was the gain too high Im assuming it would have been oscillating during spool up and after putting the heli into a hover??

Does it sound like a link failure or did I screw something up in the setup?

(Fortunately the damage is minimal as i was only 3-4m in the air... blades, boom, main shaft, boom supports..)
Too high gain = fast wag or similar feeling like low gain (bounce, indirect controls feeling). From your post i suspect link (this could also caused vibrations).
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Old 01-05-2012, 02:20 PM   #5
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Quote:
Originally Posted by swalko View Post
G-T5 is still in same mode, no rate/heading hold switch. "Balancing on a ball" = incorrect P/I ratio, propably low I.
That is incorrect, you just cant tell because you fly a bus! Try it on a 50 size heli with aggressive 3D setup!!!
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Old 01-05-2012, 03:14 PM   #6
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Thanks for the replies..

It was definitely white numbers on black background at 100%..
P-I ratio: I was using default settings as the posts ive read indicated these work quite well..

Ill fix up the heli and give it another go..
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Old 01-05-2012, 03:18 PM   #7
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Originally Posted by NitroAl View Post
That is incorrect, you just cant tell because you fly a bus! Try it on a 50 size heli with aggressive 3D setup!!!
1.) On EVERY size you will CLEARLY notice difference between rate and heading hold.
2.) In rate mode you will not be able to do hands off inverted hover very close to ground.
3.) Even though i did not noticed anything, it is possible that negative/positive total gain value may change something, but definately it is not a switch between rate and heading hold.
4.) Here is a experience with something like rate mode:

Quote:
Originally Posted by HeliBenj View Post
So are you wondering what would happen if you took off a Trex 500 Pro with the GT5 while still in a menu, say, the pitch menu? Would make for a fun flight, the heli would drift widly all over the place requiring constant correction to keep in the air and land safely.
Of course this is just theoretical, I'm not stupid enough to do it twice on the same pack


Someone had to try it, right?

Now it makes me think ,the heli was consistently drifting hard to the left and to the back. Does this mean my swash is not level? My CoG is correct and the swash sure looked level to me (eyeball + horns 90 and rods the same length)
Quote:
Originally Posted by 360Wings View Post
Thanks for the replies..

It was definitely white numbers on black background at 100%..
P-I ratio: I was using default settings as the posts ive read indicated these work quite well..

Ill fix up the heli and give it another go..
Then please post your result .

Last edited by swalko; 01-06-2012 at 05:26 AM..
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Old 01-08-2012, 09:41 AM   #8
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Since you had it in a hover it means your compensation direction is correct, i would check your power supply, could be a brownout reset, my friends mini titan did it twice now he replaced everything on the heli except bec so seems very likely the cause,
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Old 01-08-2012, 09:55 PM   #9
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Originally Posted by Stolla View Post
Since you had it in a hover it means your compensation direction is correct, i would check your power supply, could be a brownout reset, my friends mini titan did it twice now he replaced everything on the heli except bec so seems very likely the cause,
I didnt really consider that as a potential culprit as I have TT.. I always assumed static hits (im assuming that what you mean by brownout?) were an issue with belts only?

Next time ill use a dedicated rx pack instead of the BEC...

Parts have been ordered. Hopefully they arrive before the weekend..
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Old 01-08-2012, 11:28 PM   #10
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No not static, brownout - power reset can happen if servos draw more current than your bec/reg can provide, flybarless systems usually draws a lot more current from the servos, some are worse than others
What heli and setup?
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