h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Ahhh... I should stop pulling now then....?

Ah... the standard disclaimer. *Sigh*

What has upset me a bit is the fact that there doesn't seem to have been any postings from helecopter pilots yet. This begs the question Why are there no helicopter pilots visiting H2G2? and if there are, are they rolling around on the floor laughing at our theories that they haven't been able to contain themeselves long enough to reply.

well, I'm a fixed wing pilot, not that that helps, but when stunt men in folms grab the skid, the helicopters lurch. This leads me to believe that ther are inherantly unstable ans so they should be easy to pull along ?

I just looked at my spelling. Sorry.

Ok, lets see...
If the pilot was actively trying to keep his craft at the very least on a level plane, but not moving in any direction, it WOULD be possible to tow it along from the ground. BUT - due to the fact that a hovering copter would be a tad up, I am assuming, it would take much more strength than any mere mortal could muster.

Maybe tying the rope to the handy roof-rack of a large car, with everything -VERY- secure, and moving slowly to avoid startling the pilot, you could take down a powerline- and overpass-free stretch of road for a good while, at least until you were pulled over by the local Traffic Enforcement Officer.

But then you could just tell them you're really paranoid about traffic tie-ups, so you have your own personal traffic copter it tow, just for that occasion.

So if we hook a bumblebee to a lead connected to a whirlybird, the whirlybird will swirl among the daffodils?

Some more thoughts... Helicopters are dynamically unstable, which means that if you let go of the controls, the chopper will fall out of the sky. They need the pilot to regularly do something with the controls (about every 5 seconds in light winds).

If someone pulled on the rope from the ground, the pilot would counteract the movement by adjusting the controls, and the helicopter would remain stationary (if that's what the pilot wanted). If the pilot didn't touch the controls, the helicopter would start to oscillate back and forth, getting increasingly more interesting, until it falls out of the sky. How quickly this happens would depend on several things (wind speed and direction, mass of the chopper, where the centre of gravity is, where the rope is connected, etc.).

I've checked this theory with a couple of fellow helicopter pilots and we think it's correct.

How about that!!! a reply from a helicopter pilot, I was beginning to think that it was only us sea fareing land lubers (and the occassional fixed wing pilot) that visited these hallowed halls.
Hey Anonymouse do you think he is really a hellicopter pilot or is he having us on.

And how come Freds posting has Helicopters in bold type before his user name???

The question about pushing or pulling around hovering helicopters might be more applicable to something I happen to know quite a bit about: the pushing or pulling around of hovering hot air baloons.
A hot air baloon is something you will see quite frequently around this time of year if you live where I do: New Mexico, USA. Just south of me, in Albuquerque, there is the annual Hot Air Baloon Fiesta, which lasts usually 9 days or so, and has hundreds of hot air baloons ascending the local skyline every morning around dawn.

If you have been lucky enough to see one of them launch first-hand, perhaps you've noticed a fair amount of lunatics running around the gondola during this time yelling at you to get the hell out of the way and also running you over with a large pickup truck. That's us - the crew. Oh, and if you were that big guy last year with the maroon shirt and earplugs? I'm very sorry about the camera - it wasn't a real Hassleblad, was it? Damn.

Anyway, I've been crewing for enough balooning events in the last 10 years, and I can tell you that a hot air baloon, while it may be hovering quite nicely with a net weight near zero, it still has a LOT of mass! I assume this to be the same case with a hovering helicopter. In other words, you'd better be an extraordinarly strong individual (the likes of which would make even Magnus per Magnusson walk away from without a challenge) if you plan to move a hot air baloon around by pulling it with a rope. Sure, you can get it to lurch, but actually getting it to move a good 30 yards or so, that's different. What I'd call a "small" hot air baloon, holding only 87,000 ft^3 of air and two 200-lb people and some propane and burners and radio and other such knick-knacks (the crew carries all the champagne in the chase vehicle, in case you're wondering) will have a mass approximately equal to 2.5 tons. One person CAN pull that baby around, with EXREME effort, but it's like trying to pull a Chevy Suburban. Uphill. With the brake on.

I'd wager that a 2.5 ton hovering helicopter (which seems to be pretty darn small, but I wouldn't really know) would feel exactly the same to whomever is unlucky enough to be trying to pull it around on the other end.

Just my $4.37 worth [adjusted for inflation].

Pauline: The reason for the bold topic is probably because of a small topic adjustment (even if it was later erased)...

Hmm... How does it compare with lugging around a stubborn, overweight pregnant horse that is definitely NOT floating on air?

Because he corrected the spelling

I have this image in my mind now of you carrying a horse around your neck, like in the pictures of a hunter bringing home the deer in days of olde.

LOL!! A foal, maybe... A full-grown and pregnant horse? I doubt it...

I'm sory but I dissagree, I have been up in many a hot air balloon and you can't compare it to a helicopter. remember we are talking about a windless day, and as you know (if you have ever been up in a hot balloon,)there are no windless days, there is allwqys a slight breeze. If there was no wind at all the hot air Balloon could be moved around without a problem, but even a 1 mph wind mens the balloon has to be anchored to something because of the total mass of the balloon in the air, the balloon becomes part of the air that is moving, whereas a helicopter is more aerodynamic.

I'm sory but I dissagree, I have been up in many a hot air balloon and you can't compare it to a helicopter. remember we are talking about a windless day, and as you know (if you have ever been up in a hot balloon,)there are no windless days, there is allwqys a slight breeze. If there was no wind at all the hot air Balloon could be moved around without a problem, but even a 1 mph wind mens the balloon has to be anchored to something because of the total mass of the balloon in the air, the balloon becomes part of the air that is moving, whereas a helicopter is more aerodynamic.

Perhaps away?

I think our baloonist friend is on to the right track.
In order to move something, you have to give it a velocity.
Now (school physics, I apologise ) force equals mass times velocity.

So - to give a 5000kg helicopter a velocity of 2m/s would need a force of 10kilo-newtons. I'm not sure how strong you are - but I'd give it a miss.

To put it in a more simple way, for a wheeled helicopter, the force required to roll it along the ground is only about 10% more than would be required to push it along whilst airborn.

(2) [imho] Helicopters aren't inherrently unstable. When in motion the rotors bend upwards slightly in a very shallow bowl shape. If you tip the helicopter towards one edge of this the lift created by the rotors at that part of the cycle increases...tending to lift the helicopter back to level flight.

A sad reflection on my education

The correct equation is, of course, F=MA
Force = mass * acceleration

So to "accelerate" the helicopter by 2ms-1 would take 10kilo-newtons, and that is assuming it has no air resistance at all (something later education assures me is impossible).

If Mr. Burgess or any other of my various physics teachers is reading this - you're right, I wasn't paying attention.