Barrel rolls
Joined: Nov 2003
Posts: 185
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The ability to go inverted in flight depends largely on the rotor head design.
The fully articulated head cannot take low G situations...the semi-rigid system (R22 B206) is worse but both have the problem that the aircraft doesn't necessarily follow the disc in a low G condition. This can cause mast bumping / droop stop pounding or a general loss of controllability.
Imagine towing a car up a hill, using a slow tractor and a tow rope. Then you have to make a sharp U-turn back down the hill. It's not going to work because the towed car doesn't follow your tractor. The wheels of the tractor would interfere with the tow rope! The only way you could do it was to rigidly connect the car, or to power through the turn (keeping the rope taut). The H269 doesn't have enough power to keep a positive lift throught the roll.
Well that's the best analogy I can come up with. Only a few helicopters with Rigid rotor systems have the capability to go inverted.
The other limiting factor is the fuel system. In the H269 it is a 'gravity fed' fuel system. No need to explain what inverted flight would do to that!
cl12pv2s
The fully articulated head cannot take low G situations...the semi-rigid system (R22 B206) is worse but both have the problem that the aircraft doesn't necessarily follow the disc in a low G condition. This can cause mast bumping / droop stop pounding or a general loss of controllability.
Imagine towing a car up a hill, using a slow tractor and a tow rope. Then you have to make a sharp U-turn back down the hill. It's not going to work because the towed car doesn't follow your tractor. The wheels of the tractor would interfere with the tow rope! The only way you could do it was to rigidly connect the car, or to power through the turn (keeping the rope taut). The H269 doesn't have enough power to keep a positive lift throught the roll.
Well that's the best analogy I can come up with. Only a few helicopters with Rigid rotor systems have the capability to go inverted.
The other limiting factor is the fuel system. In the H269 it is a 'gravity fed' fuel system. No need to explain what inverted flight would do to that!
cl12pv2s
Last edited by cl12pv2s; 4th April 2005 at 09:47.
Gentleman Aviator
Joined: Jul 2000
Posts: 3,722
Likes: 91
From: Teetering Towers - somewhere in the Shires
In theory of course a barrel roll is a manoeuvre that can be carried out entirely under positive g.......
....... but in practice, please don't do it in any (rotary) aircraft I'm likely to fly (I've got a little list of Lynx numbers) or anywhere the bits might damage me or my loved ones.......
....... but in practice, please don't do it in any (rotary) aircraft I'm likely to fly (I've got a little list of Lynx numbers) or anywhere the bits might damage me or my loved ones.......
Joined: Mar 2001
Posts: 64
Likes: 0
From: Scotland
Teetering Head has hit it on the nail.
Yes it is possible in a fully articulated (preferably small, maneouvrable helicopter). You would need to get the nose very high before commiting to the roll. Yes you need to keep positive "g" on throughout the roll and yes I have witnessed it in a gazelle on several occasions.
Recommendations don't do it, it is potentially very dangerous. If you fly teetering heads read a different subject.
Yes it is possible in a fully articulated (preferably small, maneouvrable helicopter). You would need to get the nose very high before commiting to the roll. Yes you need to keep positive "g" on throughout the roll and yes I have witnessed it in a gazelle on several occasions.
Recommendations don't do it, it is potentially very dangerous. If you fly teetering heads read a different subject.
Joined: Jun 2002
Posts: 352
Likes: 0
From: Andover, Hampshire
Barrell roll and loop are possible in a Gazelle HT3. I am living proof that it can be done and before anyone asks I was not at the controls at the time, but I trusted the chap in the other seat without question. It was an outstanding experience......once!!
Purveyor of Egg Liqueur to Lucifer
Joined: Nov 2002
Aviation Qualifications: ATPL
Posts: 4,752
Likes: 64
From: Alles über die platz
This is taken by myself, but my timing wasn't quite right for 'the shot'.
The photos taken the next day were better, but unfortunately I don't have a copy, although I was in the a/c.
They were also taken by a proper photographer who got the shot.
R/C helicopters can have a decent amount of negative pitch which enables them to do inverted flight.
A quick flick of the control reversal switch makes the control inputs 'normal'.
A google search brought up;
Quote from site; "Here is the result of my attempt at inverted hovering."
Simple answer, DON'T DO IT! real or model.
