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HomeAircraftHelicopterFlybarless Rotor Head SystemsOther › Almost lost my trex 500, MiniV, help please!
01-20-2010 12:30 PM  8 years agoPost 21
Stolla

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Port elizabeth South Africa

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The heli will not correct itself in trim flight, you have to correct it which is the whole idea, you let the heli drift for a while then correct it a couple of times that's how it learns. Only when you fly in normal mode will the heli be stable. As mentioned do a normal flight and then see what happens, do a piro while flying forward if the heli stays level youre OK.

Common sense may not be common after all

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01-20-2010 01:24 PM  8 years agoPost 22
Justin Stuart (RIP)

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Plano, Texas

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Here is how I understand the correct trim flight sequence: Set the heli up in a hover. Let is drift to one side or the other for awhile. The computer will correct a "click" of trim every second or so. If the heli gets too far away, you will have to give it correction to bring it back in front of you. As soon as it is flying level, land immediately without giving any more cyclic input and unplug the RX battery. Wait 10 seconds before you restart so the information will be saved.

The green bar only measures how long the trim flight was. If the heli is almost perfectly balanced to begin with, you only need a second or two of trim flight.

Personally, I think the trim flight is a very good way to almost crash. Here is what I do with the small helis (although I don't recommend it due to injury). Hold the heli up by the skids in your right hand above your head in trim flight mode. Start it up and let the rotors get up to speed giving just enough collective so that the heli is weightless in your hand. You will feel the computer give corrections until the heli is weightless in your hand and had no tendancy to drift. Then kill the motor as fast as possible and unplug the ESC. It will be perfectly trimmed. I find this aceptable for a 250 and maybe for a 450 (if you are careful). Maybe you could make up some sort of "holder" for the 500 to do the same. Like a pivoting table?

Letting the heli drift all the way across the field is perhaps as dangerous as spooling up the heli in your hand. But you need to get it trimmed, right?

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01-20-2010 01:52 PM  8 years agoPost 23
Stolla

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Port elizabeth South Africa

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YEah i would not recommend your method but if it works for you......
I'm not doing trim flights anymore either since we always have wind so spend time in getting setup and cg right then no need.

Common sense may not be common after all

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01-20-2010 02:20 PM  8 years agoPost 24
Justin Stuart (RIP)

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Plano, Texas

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I have thought of building a pivoting table with a ball joint in the middle which would let the heli tilt front-to-back and side-to-side so that it could be trim flighted in a more controlled fashion. When V4.0 first came out, I tried over and over to get a good trim flight. Meanwhile, the heli was floating all over the place almost hitting things at the field.

I think V-stabi version 4.0.21 needs to allow manual input of trim variables. This would solve a lot of issues.

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01-20-2010 05:07 PM  8 years agoPost 25
Bob Wales (RIP)

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Lebanon CT

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Ok I was under the impression that during trim flight I was not supposed to give any cyclic inputs as the computer would be trying to figure out what it needed to do and compensate for what it was doing .

So I should be giving stick inputs during trim flight as to keep it in front of me. Is this correct ?

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01-20-2010 05:19 PM  8 years agoPost 26
Bob Wales (RIP)

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Lebanon CT

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STOLLA
YEah i would not recommend your method but if it works for you......
I'm not doing trim flights anymore either since we always have wind so spend time in getting setup and cg right then no need.
I have taken the time to set this up properly as previously stated with swash leveler and digital calipers on the links to the head and gone through all of the setup menus as posted on the videos.

So do you recommend taking it out of trim flight and just try flying it as I am in the same situation you are of having perfect conditions to do the trim flight in which is why I have not been able to fly it again since my last.
I thought the trim flight was a necessary step in order to use the vbar system.

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01-21-2010 09:20 AM  8 years agoPost 27
Stolla

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Port elizabeth South Africa

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Officially the trim flight is needed as very few people have the knowledge and know how to set a heli up properly so basically the heli will trim itself in. Unofficially you don't need it if you have a perfect setup, i.e all trims and subtrims in software and transmitter so servo arms are 90 degrees at midstick with swash level, at full pos and neg trimmed so swash stay level, of course in setup mode. If that's the case and importantly cg is correct, (again follow guru mrmels advice to put a rod under the skids directly under the mainshaft with canopy on and it should balance for cg) then the heli should fly perfect, in fact a trimflight in wind will make it fly worse than no trimflight

Jrock i don't know what you mean by manual input variables for trim as in fact you have to trim it in the software there is buttons for trim at mid as well as full pos and neg stick to get the swash and servos level. You also adjust subtrim and atv in radio to get values to correspond in software to 100(atv)-0(subtrim)-100 (atv)

So in essence if your setup is asmentioned above you can go fly it, just please check sensors before taking off they should compensate against direction of tilt!

Common sense may not be common after all

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01-21-2010 02:00 PM  8 years agoPost 28
Justin Stuart (RIP)

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Plano, Texas

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Jrock i don't know what you mean by manual input variables for trim as in fact you have to trim it in the software there is buttons for trim at mid as well as full pos and neg stick to get the swash and servos level. You also adjust subtrim and atv in radio to get values to correspond in software to 100(atv)-0(subtrim)-100 (atv)
It's my understanding that a trim flight is supposed to compensate for the heli not being perfectly balanced. Leveling the swash is another issue. Sometimes it is impossible to move things around so that the heli is perfectly balanced, thus a trim flight is needed to compensate. Would be nice to enter this information in by hand rather than to let the computer do it.

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01-21-2010 05:45 PM  8 years agoPost 29
Stolla

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Port elizabeth South Africa

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Trimflight will follow your inputs, if the heli is for instance nose heavy you have to pull elevator to bring it in so youll note a trim value in elevator. Problem is vbar can not correct for incorrect cg as when you go inverted for instance autotrim values would have to be reversed. so although vbar will compensate to an extent you wont get it to fly well at all if cg is incorrect. Except of course on a scale machine that stays upright.
That's why it's important to get cg perfect as well as level swash for a perfect flying heli, sure it would fly with wrong cg and uneven swash but not nearly as well as the correct setup.

Remember it's the same for a normal flybar heli as well.

Common sense may not be common after all

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01-24-2010 01:15 PM  8 years agoPost 30
Bob Wales (RIP)

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Lebanon CT

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Thanks for all of the help guys.
I took it out of trim flight mode and flew it yesterday and it flew great. Unbelievable that thing flew like it was on rails.
I will wait for spring and try to do the trim flight just to see if it improves any.
Thanks again Stolla.

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01-25-2010 04:21 AM  8 years agoPost 31
Stolla

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Port elizabeth South Africa

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Great news, enjoy!

Common sense may not be common after all

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