Helicopter Aeros & Display Flying
Joined: Nov 2001
Posts: 116
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From: San Jose, CA
Nick,
This discussion brings up something I've wondered about for some time... I've read most of the available books about Cobra ops in Vietnam - and am under the impression that the pilots would regularly perform maneuvers in getting set up for a "run" that would appear to be just the sort of thing that a teetering rotor wouldn't like very much - i.e. an unloaded dive. Were these guys just real careful to always keep the rotor loaded?
Also, I have some OH-6 training tapes from '67/'68 that show "wingover" type maneuvers... I have the same question about those; it seems like that would unload the (non-teetering, of course) main rotor.
thanks,
Dave Blevins
This discussion brings up something I've wondered about for some time... I've read most of the available books about Cobra ops in Vietnam - and am under the impression that the pilots would regularly perform maneuvers in getting set up for a "run" that would appear to be just the sort of thing that a teetering rotor wouldn't like very much - i.e. an unloaded dive. Were these guys just real careful to always keep the rotor loaded?
Also, I have some OH-6 training tapes from '67/'68 that show "wingover" type maneuvers... I have the same question about those; it seems like that would unload the (non-teetering, of course) main rotor.
thanks,
Dave Blevins
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blave,
The rocket run entry used to be done as a bunt or low g pushover, but in 1969 an emergency flight warning went out for Cobras to avoid the low g. We simply pushed over a bit more gently, with no difficutly. The dive is a 1 g maneuver, and no sweat.
We all did "wingovers" or target returns, and they made us feel quite aerobatic. As long as you pull 1 g or more in the whole maneuver, it could be done safely.
The OH-6, and the UH-60, AH-64 and the S-76 all have moderate offset main rotor heads (4 to 5 %) that permit quite a bit of control at zero g. These aircraft can all be coaxed into impressive shows. We express the percent hinge offset as the ratio of the flapping hinge to the rotor radius, so a 25 foot rotor radius with the flapping hinge 1 foot from the center of the mast has 4% offset. This is a measure of the snappiness of the cyclic, and also of the control power remaining at zero g. Later in the week I'll post a little discussion of hinge offset for those who wish to go deeper into it. For a BO-105/BK-117/RAH-66 the hinge offset is in the 10 to 15% range, ideal for such messing around.
The rocket run entry used to be done as a bunt or low g pushover, but in 1969 an emergency flight warning went out for Cobras to avoid the low g. We simply pushed over a bit more gently, with no difficutly. The dive is a 1 g maneuver, and no sweat.
We all did "wingovers" or target returns, and they made us feel quite aerobatic. As long as you pull 1 g or more in the whole maneuver, it could be done safely.
The OH-6, and the UH-60, AH-64 and the S-76 all have moderate offset main rotor heads (4 to 5 %) that permit quite a bit of control at zero g. These aircraft can all be coaxed into impressive shows. We express the percent hinge offset as the ratio of the flapping hinge to the rotor radius, so a 25 foot rotor radius with the flapping hinge 1 foot from the center of the mast has 4% offset. This is a measure of the snappiness of the cyclic, and also of the control power remaining at zero g. Later in the week I'll post a little discussion of hinge offset for those who wish to go deeper into it. For a BO-105/BK-117/RAH-66 the hinge offset is in the 10 to 15% range, ideal for such messing around.
Joined: May 2002
Aviation Qualifications: ATP+Mil
Posts: 18,633
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From: Downeast
Nick....now I have never been accused of being "bright" and afterall...heck...I read about it how to do it....any well gee....but you are right.....my internal self preservation gyro...has never let me down for those intentional misdeameanors I have been tempted to commit. It has however, deserted me on more than one time when unintentional felonies have occurred!
Joined: Feb 2001
Posts: 103
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From: the other America
-------------------Quote N Lappos------------------------------------
Aerobatics in helos in general should be left to the bar talk. Doing this stuff without a test pilot and a good insurance policy is not too bright, definately illegal, and not conducive to longevity (to paraphrase Bomber Harris).
Brings to mind the bloke in the ENG MD600 (LA?), last words were something like "watch this" as he attempted to roll the ac in front of friends alongside in a R44.They got to watch as the ac chopped the tail off mid manouvre, plummeted to earth killing pilot + cameraman.
Kinda ruined everyone's day
Joined: Jul 2000
Posts: 6
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From: Europe
If you want to barrel roll things - then get a plank and do it in that. Helicopters are great fun for lots of things...but let's be reasonable about it!
Keep the blue above the brown. Just remember that ones' rotor blades have a nasty habit of coming down (or up) to meet you if you're doing something silly.
I say this as a young pilot who intends to get old!
Flysafe (and the right way up!!)
Keep the blue above the brown. Just remember that ones' rotor blades have a nasty habit of coming down (or up) to meet you if you're doing something silly.
I say this as a young pilot who intends to get old!
Flysafe (and the right way up!!)
Joined: Jul 2000
Posts: 28
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From: West Yorkshire
Buttline,
Having in my past had the pleasure (if that's the correct word) of practising and performing limited aerobatics in the lynx heli I would advise you not to even think about it!! The accident always starts with "I wonder if" unless you are with a test pilot in a competent machine!!!!
Nick,
Do you know of, or remember a certain F. Zimmerman (think thats the correct name) who used to throw a BO105 around a few years ago - always thought that he was a guy with a death wish!
FLIR
Having in my past had the pleasure (if that's the correct word) of practising and performing limited aerobatics in the lynx heli I would advise you not to even think about it!! The accident always starts with "I wonder if" unless you are with a test pilot in a competent machine!!!!
Nick,
Do you know of, or remember a certain F. Zimmerman (think thats the correct name) who used to throw a BO105 around a few years ago - always thought that he was a guy with a death wish!
FLIR
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Aerobatics in helos is like gilding lillies
FLIR,
I do recall his name and fame, I saw a video he performed in while flying a PAH-1 BO-105. It was awsome.
Also Sigfried Hoffman, who died mysteriously while filming a movie in the States, even with his experience, something got him.
I have done quite a bit of helo aerobatics, many of the Discovery Channel shots of split S or roll maneuvers of Sikorsky's are mine, but I admit I still haven't figured out why.....
No other flying machine can pull to a stop, pedal turn and then sprint away. To toss a helo around until it performs like a Spad proves little, I think. Much better to do what we do best, and get better at that.
Nick
I do recall his name and fame, I saw a video he performed in while flying a PAH-1 BO-105. It was awsome.
Also Sigfried Hoffman, who died mysteriously while filming a movie in the States, even with his experience, something got him.
I have done quite a bit of helo aerobatics, many of the Discovery Channel shots of split S or roll maneuvers of Sikorsky's are mine, but I admit I still haven't figured out why.....
No other flying machine can pull to a stop, pedal turn and then sprint away. To toss a helo around until it performs like a Spad proves little, I think. Much better to do what we do best, and get better at that.
Nick
Joined: May 2002
Posts: 184
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From: uk
Low N aaahrr and Flir,
I respectfully refer you to the first sentence in my original post..."Don't worry, I have no intention of trying it but.." Actually, if the truth be known, I'm a bit of a coward now I've past 30!
I've seen it done in Lynx's, Gazelles and of course Nick's stuff on Discovery but they never show what's going on with the controls...
I respectfully refer you to the first sentence in my original post..."Don't worry, I have no intention of trying it but.." Actually, if the truth be known, I'm a bit of a coward now I've past 30!
I've seen it done in Lynx's, Gazelles and of course Nick's stuff on Discovery but they never show what's going on with the controls...
Joined: Jun 2001
Posts: 73
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From: A big comfy armchair
I've sat in Lynxes while the QHI beside me demonstrated back flips. Fun but very scary. That, more than anything else confirmed where my own limitations lie. The machine might be able to do it but not if I'm the pilot!
Joined: Nov 2001
Posts: 264
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From: Rhode Island, USA
Okay can a civilian ask a question?
Thank you. Is it really possible to fly a heilocopter up side down or is a loop de loop sort of a controlled stall that you hope to come out of before the Laws of Physics start working against you? If I didn't ask it correctly try it this way is the photo with the horizon upside down and the binoculars floating in midair real or PhotoStudio?
Thanks
Thank you. Is it really possible to fly a heilocopter up side down or is a loop de loop sort of a controlled stall that you hope to come out of before the Laws of Physics start working against you? If I didn't ask it correctly try it this way is the photo with the horizon upside down and the binoculars floating in midair real or PhotoStudio?
Thanks
GunsssR4ever
Joined: Sep 1999
Posts: 3,816
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From: Out there somewhere ...
Loops and aerobatics
Lo Richard,
A quick answer .. yes certain helicopters CAN do a loop like a BK 117 (with certain mod's like clipping part of the vertical stabilizer)
The big criteria is the Rotor HEAD must be of the Fixed - type and not the type that you find on a Allouette / Gazelle / Puma or Mi-24 for that matter .
They all have dragging hinges and use hydraulics to lead and lag ... eischhh this is a long subject - where do I start ..
To answer you question - yes they can and a very well known video clip is of a massivve CH53 "jolly Green Giant" doing a slow roll ... sorry ran out of power om Laptop - power out !
Gunsss
A quick answer .. yes certain helicopters CAN do a loop like a BK 117 (with certain mod's like clipping part of the vertical stabilizer)
The big criteria is the Rotor HEAD must be of the Fixed - type and not the type that you find on a Allouette / Gazelle / Puma or Mi-24 for that matter .
They all have dragging hinges and use hydraulics to lead and lag ... eischhh this is a long subject - where do I start ..
To answer you question - yes they can and a very well known video clip is of a massivve CH53 "jolly Green Giant" doing a slow roll ... sorry ran out of power om Laptop - power out !
Gunsss
GunsssR4ever
Joined: Sep 1999
Posts: 3,816
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From: Out there somewhere ...
Now that you have seen it Richard ... imagine a slow roll ... I am searching for the video ... can not find it on my hard drive and yes ... damn - I had it ! 
Take note : Slow roll NOT a loop - maybe it can do one from 20 000 vt AGL ?
Take note : Slow roll NOT a loop - maybe it can do one from 20 000 vt AGL ?
.
Joined: Nov 2001
Posts: 264
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From: Rhode Island, USA
Excuse me guys
Would someone please clarify for a civilian what a helio can do. I recognize that helios come in different shapes and sizes. I suspect that chinooks handle very differently then a cobra, what about a Hind M24?, or a Bell. I don't expect a primer on every airframe made, just an short outline of what a frame of a certain size can do. I know from years of experiance what I can do in different power boats and sail boats. Happy to share info if you care
Basic can you loop a helio for real or do you just throw it up and hope it comes through the loop before you run out of air?
Thanks
Would someone please clarify for a civilian what a helio can do. I recognize that helios come in different shapes and sizes. I suspect that chinooks handle very differently then a cobra, what about a Hind M24?, or a Bell. I don't expect a primer on every airframe made, just an short outline of what a frame of a certain size can do. I know from years of experiance what I can do in different power boats and sail boats. Happy to share info if you care
Basic can you loop a helio for real or do you just throw it up and hope it comes through the loop before you run out of air?
Thanks
Iconoclast
Joined: Sep 2000
Posts: 2,132
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From: The home of Dudley Dooright-Where the lead dog is the only one that gets a change of scenery.
Huh????
To: Gunship
Please explain what hydraulics are used to effect lead and lag.
They all have dragging hinges and use hydraulics to lead and lag
Joined: Feb 2002
Posts: 54
Likes: 0
From: On the seven seas
T_Richard
The answer to your question is YES. Some helicopter types CAN loop - BK117, BO105 & Eurocopter Tiger (they are the three that I have seen).
Not all helicopters can loop due to the characteristics of their rotor systems. The beauty of the BO105 and BK117 is that their rotor systems are hingeless (or rigid for want of a better word). What this means is that they have no hinges to allow leading, lagging or flapping of the blades as they fly through the air. The blades themselves do these three functions. The beauty of this system is that they retain control power even down to -1g. To be precise, the BK117 and BO105 retains approx. 90% control power at -1g. What this means is that the rotor system has 90% ability to move into a new attitude at -1g. This is pretty good for a helicopter.
Down side - the ride can be a little bumpy but after the pilot becomes familiar with the flying characteristics - not too bad.
Enough of the Nerdy stuff.
The answer to your question is YES. Some helicopter types CAN loop - BK117, BO105 & Eurocopter Tiger (they are the three that I have seen).
Not all helicopters can loop due to the characteristics of their rotor systems. The beauty of the BO105 and BK117 is that their rotor systems are hingeless (or rigid for want of a better word). What this means is that they have no hinges to allow leading, lagging or flapping of the blades as they fly through the air. The blades themselves do these three functions. The beauty of this system is that they retain control power even down to -1g. To be precise, the BK117 and BO105 retains approx. 90% control power at -1g. What this means is that the rotor system has 90% ability to move into a new attitude at -1g. This is pretty good for a helicopter.
Down side - the ride can be a little bumpy but after the pilot becomes familiar with the flying characteristics - not too bad.
Enough of the Nerdy stuff.
Joined: Aug 2000
Posts: 3,670
Likes: 1
From: UK
T Richard: you have been extremely patient with us all, trying to expand your knowledge of helos. Whether some can do loops or rolls. Or is it mirrors and string technology?
Well I can honestly tell you that the real answer is:
somewhere up there in the clouds......................
Well I can honestly tell you that the real answer is:
somewhere up there in the clouds......................
GunsssR4ever
Joined: Sep 1999
Posts: 3,816
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From: Out there somewhere ...
Lu Zuckerman To: Gunship
Please explain what hydraulics are used to effect lead and lag.
Please explain what hydraulics are used to effect lead and lag.
