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Robinson R44 - Doesn't fly straight ?

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Robinson R44 - Doesn't fly straight ?

Postby specksavers » Sun Mar 03, 2013 5:48 pm

Hello everyone,

Im a big fan of flying the Robinson R44 on FG 2.10, Mac OSX.
The problem is, to make it fly in a straight line (same heading), you must make the helicopter lean on it's right a bit. If you fly with the helicopter straight forward in the air, it will turn slowly right. I don't find this very realistic to be honest, and I would like to be able to fix that.

I don't know whether it needs a trim ? (and I don't know how to trim) or the R44 does that in real life, or if he files need editing..?

Here is a picture:
Image

In that picture I am flying in a straight line, but the helicopter is leaning left to do so.. If I make it fly so it's not leaning, it will drift right..

So how can I fix this so it goes in a straight line without tilting the heli to the left?

Thanks for reading,
George.
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Re: Robinson R44 - Doesn't fly straight ?

Postby someguy » Sun Mar 03, 2013 10:28 pm

Have you ever flown a helicopter that didn't do that? I think it's normal. I can't say whether it occurs in real life, but some real heli pilots use FG and I never heard one complain about it.
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Re: Robinson R44 - Doesn't fly straight ?

Postby Philosopher » Sun Mar 03, 2013 11:01 pm

I think it's the tail rotor -- it doesn't just produce a moment (read: it doesn't just swing the tail), it also produces a little bit of lift towards the left or right. To counter this, the main lift vector (the roll angle of the main rotor) must be angled a bit to fly negate this lift towards the side, which would otherwise cause drifting to one side and possibly some other effects. Just another weird bit about helis ;).
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Re: Robinson R44 - Doesn't fly straight ?

Postby Groucho » Mon Mar 04, 2013 8:16 am

Philosopher wrote in Sun Mar 03, 2013 11:01 pm:I think it's the tail rotor -- it doesn't just produce a moment (read: it doesn't just swing the tail), it also produces a little bit of lift towards the left or right. To counter this, the main lift vector (the roll angle of the main rotor) must be angled a bit to fly negate this lift towards the side, which would otherwise cause drifting to one side and possibly some other effects. Just another weird bit about helis ;).


In fact the R44 has a counterclockwise turning rotor which means the tail rotor is on the left side of the aircraft (seen in flight direction). As the tail rotor is not elevated (eg. like on the S76, EC145, UH-1), it produces a significant push to the right which is especially noticable in hover after take-off. In forward flight where the weather vane effect usually prevents the tail from turning by tail input this push is translated into a slight right turn by the weather vane effect and the frame drag.
So the pilot has to compensate this with slight cyclic input to the left.
However I would not expect this to be as much as shown as in the screenshots attached- even in the real R22 which I have been happily able to have it under my control the effect was not as extensive as shown. Also I was wondering as in the original post it was mentioned to be forced to compensate to the right which would be unexpected from a left tail rotor mounting.

Note that the FDM for the R44 is a bit arbitrary- as far as I remember the R44 was created in a rush and equipped with a copy from the R22 FDM with minor adaptions. It has never been undergoing validation for realism. So I would not expect realistic behavior at all.
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Re: Robinson R44 - Doesn't fly straight ?

Postby someguy » Mon Mar 04, 2013 4:00 pm

A better R44 FDM is kicking around. If you should see user KTE online, ask him for his revised R44. It behaves much more like a real helicopter than the rookie-friendly "official" version.
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Re: Robinson R44 - Doesn't fly straight ?

Postby specksavers » Tue Mar 05, 2013 8:48 pm

So is there any way to make it less realistic so it flys straight(er) ?
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Re: Robinson R44 - Doesn't fly straight ?

Postby sanni » Fri Mar 29, 2013 1:58 pm

You have to know that FlightGear is a simulator. That means everything should be as realistic as it can!!!! :D
And btw: philosopher wrote, what you have to do....
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Re: Robinson R44 - Doesn't fly straight ?

Postby BR-TSR » Tue Jul 02, 2013 5:46 pm

eu piloto um R44 II real, e tenho jogo com o coletivo e ciclico da thursthmaster no computador. a decolagem fica muito prejudicada por nao equalizar a RPM. voo com vento pior ainda. would be very nice if it had how to fix it. because there is much reality in flight.
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