When helicopters run out of fuel...
- Thread starter LeperousDust
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Oh yeah I know its very quick and a hard landing, was just saying how much the autorotating rotor helps you out. Its basically acting as a big umbrella 
Not too helpful with a few tons of metal underneath! Its the change in pitch of the blades close to the ground that really saves the pilots ass!
Not too helpful with a few tons of metal underneath! Its the change in pitch of the blades close to the ground that really saves the pilots ass!
1pudding1 said:Oh yeah I know its very quick and a hard landing, was just saying how much the autorotating rotor helps you out. Its basically acting as a big umbrella
Yeah, hence why rotary wing never did it for me. I don't want to have to pull a Mary Poppins manouevre when my engine quits, I prefer a nice glide into a field
That's the whole point of an autorotation. If you don't pull the collective up as you approach the ground, you bang into the ground at over 2000 feet per minute and die.
georges said:I ****** Hate these threads..
was one that went on for 2000 replies on another forum I'm on about a plane on a conveyor belt being able to take off or not
Those threads go on for ages because most of the people who post their opinion haven't a clue what they're talking about. The facts are there regardless of what some people say
[AFAIK]
The pitch (angle) of the blade creates the lift. But it also creates drag, which would eventually stop the blades without engine power. So you lessen the angle as you descend to get/keep the blades spinning and then at the right moments, change the angle to create lift, which slows the decent so you land ok.
One thing that hasn't been mentioned that when the rotors are spinning and if you are moving forward the whole disks acts (a little bit) like areoplane wing giving you more lift for less power than you get just the hover. So you don't land or take off in the hover most of the time, you always try to have some forward momentum.
I've read storys about Vietnam pilots picking up too many grunts (passengers) in hot LZ so that the helcopter could only hover on its ground effect (cushion of air between ground and rotor) and didn't have enough power to get over the trees around the clearing. So they'd go around the LZ building up speed until they get enough lift (because of the forward motion) to clear the trees. Obviously this would be when you've run out of other options etc.
[/AFAIK]
Feel free to correct any of that.
The pitch (angle) of the blade creates the lift. But it also creates drag, which would eventually stop the blades without engine power. So you lessen the angle as you descend to get/keep the blades spinning and then at the right moments, change the angle to create lift, which slows the decent so you land ok.
One thing that hasn't been mentioned that when the rotors are spinning and if you are moving forward the whole disks acts (a little bit) like areoplane wing giving you more lift for less power than you get just the hover. So you don't land or take off in the hover most of the time, you always try to have some forward momentum.
I've read storys about Vietnam pilots picking up too many grunts (passengers) in hot LZ so that the helcopter could only hover on its ground effect (cushion of air between ground and rotor) and didn't have enough power to get over the trees around the clearing. So they'd go around the LZ building up speed until they get enough lift (because of the forward motion) to clear the trees. Obviously this would be when you've run out of other options etc.
[/AFAIK]
Feel free to correct any of that.
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What you just said Sparky was a full explanation of autorotation.
Something to mention is that it takes a skilled pilot to do a successful autorotation, by successful I mean one you walk away from.
Hence why most helos have warning buzzers when you get low on fuel to give you enough time to land BEFORE you actually run out. For two reasons. One, there's a 50/50 chance an autorotation won't work due to pilot skill level/preparation/advanced warning. Two, there's an almost 100% chance there will be terminal damage done to the airframe. So your ass is walking home to tell the insurance company why you no longer own a functioning helo.
Something to mention is that it takes a skilled pilot to do a successful autorotation, by successful I mean one you walk away from.
Hence why most helos have warning buzzers when you get low on fuel to give you enough time to land BEFORE you actually run out. For two reasons. One, there's a 50/50 chance an autorotation won't work due to pilot skill level/preparation/advanced warning. Two, there's an almost 100% chance there will be terminal damage done to the airframe. So your ass is walking home to tell the insurance company why you no longer own a functioning helo.
Don
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My cousin is an Army helicopter instructor, and currently flying apachies (i think), have spoken to him about such instances when i asked him to try and fly my model helicopter (which he failed at miserably )
If you lose drive in a helicopter, you can dis-enguage (sp?) the motor and allow the rotors to auto-rotate without power, you can use your altitude to keep the rotor speed up by feathering the pitch of the blades.
Then as you approach you landing site you feed in pitch to come out of decent and use the stored energy in the blades to land safely
(read safely, not nicely )
)If you lose drive in a helicopter, you can dis-enguage (sp?) the motor and allow the rotors to auto-rotate without power, you can use your altitude to keep the rotor speed up by feathering the pitch of the blades.
Then as you approach you landing site you feed in pitch to come out of decent and use the stored energy in the blades to land safely
(read safely, not nicely )
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Replicant said:Is it true that there's a sweet spot at the rotor blades that if you shoot at it, it will drop
Well, there is whats known in pilot slang as the 'Jesus Nut'. This holds the rotor blades onto the aircraft. It is called this because when it fails, your ass belongs to Jesus.
LeperousDust said:
They can 'autogyrate', cant they? The helicopter equivalent of gliding....the pilot dips the nose, causing the chopper to move forwards - the resultant airflow over the roters allows a certain amount of control, allowing the m to land, albeit a little bumpily.
When helicopters run out of fuel... the helecopter continues to fly and will land in a safe and controlled manner.
Its due to autorotation, the blades continue to turn and produce lift. So the pilot just descends and at the last moment yanks the collective pitch and slows the helecopter right down.
I've done it many times in a electric helecopter I run outa juice and have to land without any power!
Its due to autorotation, the blades continue to turn and produce lift. So the pilot just descends and at the last moment yanks the collective pitch and slows the helecopter right down.
I've done it many times in a electric helecopter
I run outa juice and have to land without any power!
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What have i done ?
Cheers for all the replies, they're exactly what i needed. There's no argument now the offending party has been well and truly proved wrong!
?Cheers for all the replies, they're exactly what i needed. There's no argument now the offending party has been well and truly proved wrong!
Lithium said:
That's not really true. Even the most experienced pilots would be very lucky to pull off a successful autorotation in which they walk away uninjured from a serviceable helicopter. A lot of autorotations usually result in a broken helicopter and injured people.
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That wasn't the questionneo-omega said:
Soldato
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A couple of people have said autorotation is very difficult, likely to kill you, write the helicopter off etc.
Autorotation is part of the training for a ppl(H) it is not likely to cause either damage or injury. As to how difficult it is, how diffucult is passing the training. You pass the training you can and have carried out a autorotation. Hopefully without hurting yourself or damaging the Helicopter, or it would be very interesting and even more expensive training wouldn't it.
Does no one remember the program that used to be on, some ginger haired bloke (Quentin Smith) with a strange goatee, who flew round the world. Didnt he get some noob flying a helicopter in no time and get them doing a autorotation without causing death or destruction ?
TDF.
Autorotation is part of the training for a ppl(H) it is not likely to cause either damage or injury. As to how difficult it is, how diffucult is passing the training. You pass the training you can and have carried out a autorotation. Hopefully without hurting yourself or damaging the Helicopter, or it would be very interesting and even more expensive training wouldn't it.
Does no one remember the program that used to be on, some ginger haired bloke (Quentin Smith) with a strange goatee, who flew round the world. Didnt he get some noob flying a helicopter in no time and get them doing a autorotation without causing death or destruction ?
TDF.
TheDogFather said:
Training for an autorotation is different to actually carrying out one for real. When training you do it with reduced power. Most recoveries are made with power and a return to hover in which the ground isn't even touched. Recoveries to the ground can be made but again there is some power there to soften it up. Training helicopters wouldn't last too long if a landing was made with no power.