Helicopter Aeros & Display Flying
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When speaking in terms of aerobatic capability in can be Mil Mi-34 (when only 1-2 aboard) - I didn't flew it but I was really impressed with it flown over the MAKS Airshow in 1999 and 2001 - I believe it's hard to find any other light heli doing loops so easily. Nothing surprising - it was primarily designed specially for USSR national helicopter team training.
Sincerely,
Alex
Light Helicopters and Gyros in Russia
Sincerely,
Alex
Light Helicopters and Gyros in Russia
Scalextric for Men
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I once saw an MD520N doing some rather clever gyrations. This was at the all England Championships, Wroughton Wiltshire, during the early 1990`s. So to extend the thread and bring in all of the experianced pilots: Could a tail rotar/fenestron, be more or less useful than the coanda effect of MD fame; in identical circumstances and how could this be tested?
Just to be
Just to be
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Yep EC135 too, I fly the 135 but as yet have not "explored the envelope" fully yet. She is a very stable platform when executing some very challenging manoeuvres i.e. chasing a stolen car in a built up area. 
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I must say the Lynx would be hard to beat, even with the TOW launchers fitted and loaded. The early Mk1's were a bitch upside down as you tended to run out of Tail Rotor and bottle.
Apart from a disgusting lack of TR authority when heavy/high, the BK117 is heaps of fun. At mid weights, it can be encouraged to provide as much manoueverabilty as can be wished for in a civvie ship.
Now the pilot of mine who scored a ride in (and poled!) the Apache demonstrator at Avalon professed that it was an agile beast, but he would, wouldn't he
Now the pilot of mine who scored a ride in (and poled!) the Apache demonstrator at Avalon professed that it was an agile beast, but he would, wouldn't he
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I saw an MBB film about 10 years ago of a BO105 doing some very impressive things. One of them was forward movement(not sure if it would qualify as flight) tail first and inverted!!! He did a whole series of rolls, loops and hammerheads, the film was very impressive to watch. Never had the courage to try them myself, but the BO105 is fun to fly and very very responsive to control movements.
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How do you do a barrell roll?
Don't worry, I've no intention of trying it - just curious as to how it's done. Does it require a rigid head? I'm guessing the trick is to keep the disc loaded through the roll?
A true barrel roll requires a constant rate of pitch and roll throughout the manoeuvre which helicopters cannot achieve as they run out of speed. Most rolls in helicopter aerobatics are the equivalent of an aileron roll in a fixed wing - that is to say they are a product of lateral cyclic. The ability to achieve a rapid roll rate is required so hingless or semi rigid rotors have the advantage here due to increased effective hinge offset and therefore control power. The problem with snap rolling a helicopter is the twisting force experienced by the tail boom - the mass of the TR, TRgearbox and drive shafts has a lot of inertia.
The Lynx display manoeuvre called the Eagle roll starts with a gentle nose up to reduce the speed followed by full right cyclic and a lot of right pedal. The result is spectacular both from inside and outside the aircraft but you pay the penalty of vastly reduced component times and increased servicing for the pleasure.
The Lynx display manoeuvre called the Eagle roll starts with a gentle nose up to reduce the speed followed by full right cyclic and a lot of right pedal. The result is spectacular both from inside and outside the aircraft but you pay the penalty of vastly reduced component times and increased servicing for the pleasure.
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Having rolled, split S'd and looped several helicopter types, and also helped lay out Comanche's rotors for the air combat mission it accepts, here are some thoughts:
1) The barrel roll is made with a pitch up followed by lots of lateral cyclic. The aircraft scribes a spiral flight pah and holds positive G. This is the common helo roll, albeit with some speed loss as Crab suggests.
2) A rapid lateral stick input will produce zero or negative G at the 180 point, and is very much like the aileron roll in an airplane.
3) These maneuvers do not tax the tail cone or tail plyon at all, those components are designed for very high yaw thrusts, beyond anything experienced in a roll. The tail rotor blades, hub and shafting, however, are subject to lots of flapping and precession forces, and can achieve limit loads at high roll rates, maybe 100 degrees per second. Fantails like Comanche see no such forces, and so do not inhibit rolls at all.
4) Loss of control is a big factor in most helo designs due to the issues of rotor control loss at zero G. These maneuvers are quite likely to cause rotor contact at the hub, and on the fuselage, that will be catastrophic. Teetering rotors are verboten in this discussion, and low offset articulated systems are marginal.
5) The barrel roll is a semi-useless maneuver, basically for air combat when a rapid slowdown is needed (the spiral flight path is much longer, so excess speed can be burned off while tail chasing a bogie), the aileron roll is used to rapidly change the direction of the lift vector as a climb/descent or turn entry maneuver.
6) Helicopters in air combat do very different things, and they are quite a bit more maneuverable than airplanes, just not in the airshow sense. Most helo air combat will involve rapid turns and then weapons engagements, and little vertical maneuvering. Classic WWII/Vietnam airplane air combat involved jockying around to align the fixed guns with the bogie, a style of combat that is now basically obsolete. All aspect weapons and supermaneuverable aircraft (F-22, Comanche) will make snap turns and rapid shoots much more the style.
1) The barrel roll is made with a pitch up followed by lots of lateral cyclic. The aircraft scribes a spiral flight pah and holds positive G. This is the common helo roll, albeit with some speed loss as Crab suggests.
2) A rapid lateral stick input will produce zero or negative G at the 180 point, and is very much like the aileron roll in an airplane.
3) These maneuvers do not tax the tail cone or tail plyon at all, those components are designed for very high yaw thrusts, beyond anything experienced in a roll. The tail rotor blades, hub and shafting, however, are subject to lots of flapping and precession forces, and can achieve limit loads at high roll rates, maybe 100 degrees per second. Fantails like Comanche see no such forces, and so do not inhibit rolls at all.
4) Loss of control is a big factor in most helo designs due to the issues of rotor control loss at zero G. These maneuvers are quite likely to cause rotor contact at the hub, and on the fuselage, that will be catastrophic. Teetering rotors are verboten in this discussion, and low offset articulated systems are marginal.
5) The barrel roll is a semi-useless maneuver, basically for air combat when a rapid slowdown is needed (the spiral flight path is much longer, so excess speed can be burned off while tail chasing a bogie), the aileron roll is used to rapidly change the direction of the lift vector as a climb/descent or turn entry maneuver.
6) Helicopters in air combat do very different things, and they are quite a bit more maneuverable than airplanes, just not in the airshow sense. Most helo air combat will involve rapid turns and then weapons engagements, and little vertical maneuvering. Classic WWII/Vietnam airplane air combat involved jockying around to align the fixed guns with the bogie, a style of combat that is now basically obsolete. All aspect weapons and supermaneuverable aircraft (F-22, Comanche) will make snap turns and rapid shoots much more the style.
Nick ol' bean!
Being an old (sorry) err...former Cobra pilot....would you do such maneuvers in Bell built machines with their underslung, teeter totter, type rotor systems? Am I being a scardy cat here or would the a bit of mast bumping not occur just prior to rotor head disapperance?
Having flown the BO-105 and BK-117.....and being a real man about town (in my own mind anyway) I could never get the courage up to go past about 135 degrees angle of bank.....always chickened out and tucked out towards terra firma!
But then in Chinooks....we developed gentlemanly habits of flying....things like coffee makers, canned music, and walks about the cabin thanking the passengers for flying with us.....thus radical maneuvering only took place on the ground in ops when trying to dodge a flight that had a two way rifle range (borrowing Nick's phrase here) as a destination.
Being an old (sorry) err...former Cobra pilot....would you do such maneuvers in Bell built machines with their underslung, teeter totter, type rotor systems? Am I being a scardy cat here or would the a bit of mast bumping not occur just prior to rotor head disapperance?
Having flown the BO-105 and BK-117.....and being a real man about town (in my own mind anyway) I could never get the courage up to go past about 135 degrees angle of bank.....always chickened out and tucked out towards terra firma!
But then in Chinooks....we developed gentlemanly habits of flying....things like coffee makers, canned music, and walks about the cabin thanking the passengers for flying with us.....thus radical maneuvering only took place on the ground in ops when trying to dodge a flight that had a two way rifle range (borrowing Nick's phrase here) as a destination.
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SASless,
Doing anything but straight and level with moderate turns in a teetering rotor is taking a chance. The control is so very much dependant on maintaining positive G that any screw-up makes the situation a real catastrophe.
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).
Nick
Doing anything but straight and level with moderate turns in a teetering rotor is taking a chance. The control is so very much dependant on maintaining positive G that any screw-up makes the situation a real catastrophe.
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).
Nick