Movie Physics: Goldeneye (1 Viewer)

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Vince

Near the beginning of the movie there is a scene when Bond drives a motorcycle off a runway at the end of a cliff chasing a pilot-less plane that has fallen a second or two earlier. From there, he proceeds to fall as he closes the gap between himself and the plane, manages to get inside the and finally pulls the plane out of the dive preventing an untimely demise from the rocks below.

From a physical standpoint, would Bond be able to overtake and board the plane? The propeller was on as it dropped off the runway.

Huckleberry

I imagine that he would be able to reach the plane, if the cliff was high enough. At terminal velocity a man falls about 1000 feet in 6 seconds. Doesn't give him much time to catch a plane, get in it and pull it out of a dive unless that cliff is thousands of feet high.

But he would be able to catch the plane given enough time. A skydiver freefalls at about 120 mph. If they dive they can reach about 200 mph. The fastest recorded dive (from high altitude) is 321 mph. A person is much denser than a plane and can control the surface area in the direction he is travelling to reduce the drag. A person can fall faster than an idling plane. (not one accelerating downwards)

Danger

Gold Member
Huckleberry said:
A person is much denser than a plane and can control the surface area in the direction he is travelling to reduce the drag.
Sorry to all involved, but I just have to bring up Jonathan Livingstone Seagull.
I'll go back to GD now...

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Huckleberry

http://suchit.net/inspiration/JonathanLivingStoneSeagull.html [Broken]

Pulling out of a dive like that would rip the wings off of the plane?

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whozum

Dont forget to include the James-Bond factor, which makes most normally impossible actions a walk in the park.

Danger

Gold Member
Huckleberry said:
Pulling out of a dive like that would rip the wings off of the plane?
Okay... It's been about 25 years since I last read that book (never saw the movie), and I'm not about to follow that whole thing on-line. I will tell you this, however... Richard Bach is one incredibly accomplished pilot, who would not write anything that isn't aerodynamically sound. He was one of the first owners of a BD5J, which is essentially a jet-powered bathtub with wings, and his book "Stranger to the Ground" is a beautiful account of ferrying a Sabre jet Stateside from Europe. You can't really equate bird flight to mechanical flight, because at this point of technology we can't come close to mimicking them. If you could blend the reflexes and manoeuvrability of a cat with the aerodynamics of an F-14, you might get close to being a bird as far as flight goes. You would still never be able to feel the reality. As a former, and I hope sometime again, pilot, all that I can say is that we put on an aeroplane like a suit and wear it where we want to go. It's an extension of our bodies, like skates to a hockey player. In a rare display of vulnerability (outside of PM's), I will say that the only time that I was absolutely happy and at home was in the air, and I've been grounded for 30 years.

Vince

Good points about the wings coming off, I did not consider that.

But frankly, I primarily wanted to know if a human being could find a way to fall faster than a plane. I know that gravity causes objects to accelerate at 9.8 m/s^2 until they reach their terminal velocities and I understand from your post that a skydiver can reach a terminal velocity of 200 mph, but I can't quite figure it out since I have no idea how I'd begin calculating the terminal velocity of the falling plane.

Since the plane actually traveled down the runway before plunging down the cliff, it should be accelerating greater than 9.8 m/s^2 since the engines were running, correct?

Huckleberry

http://www.wpafb.af.mil/museum/eagles/kittnger.htm
During this project there were three high altitude jumps accomplished from a balloon-supported gondola--from 76,400 on November 16, 1958, from 74,700 25 days later, and on August 16, 1960, from 102,800 feet, the highest altitude from which man has jumped. In freefall for 4.5 minutes at speeds up to 714 mph and temperatures as low as -94 degrees Fahrenheit, Kittinger opened his parachute at 18,000 feet. In addition to the altitude record, he set records for longest freefall and fastest speed by a man (without an aircraft!)
I was wrong about the 321 mph freefall record. This guy over doubled that! He broke the sound barrier without a vehicle! Notice he fell from over 100'000 ft where there is much less air resistance.

This site goes over some of the formulas.
http://www.grc.nasa.gov/WWW/K-12/airplane/termv.html

I don't know what kind of plane is in the Bond movie. I'm assuming it is a small prop plane. If it's propellor was accelerating it forward then it would also accelerate it downward after it went over the edge. The plane will fall at less than g because it is not in a vacuum. As it displaces air this produces drag. This gives Bond a chance to catch it. Bond in a dive has less downward surface area/weight than a plane and this allows him to fall faster. The plane accelerating downward doesn't help any, but I think he might eventually be able to catch it.

Frankly, I wouldn't be very hopeful for Bond or the plane if this was a real situation.

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whozum

No the plane's acceleration will follow the expression
$$\vec{a}_{net}} = \frac{F_{grav} - F_{drag}}{m_{plane}}$$ given by Newton's 2nd Law.

where The drag force represents air resistance. I'm sure you could find out this value online for a 747 or something similar. It will NOT be accelerating at 9.8m/s^2. Objects accelerate at 9.8m/s^2 when gravity is the only force acting on them.

whozum

True, even if the plane on a very high cliff, for a 3 mile fall (~5000m) they would hit the ground in 31.9 seconds neglecting air resistance.

Danger

Gold Member
Vince;
My apologies for temporarily diverting your thread. If it makes any difference, that was something that I've been having to get off of my chest for 30 years and you provided the opportunity to do so. Thank you.

KingNothing

I highly doubt you can find a number for *just* vertical air resistance of a plane falling straight down. Planes were meant to have a certain airflow going about the longitudinal axis of the plane, so it will probably be very hard to find this number.

Huckleberry

True, but considering that airplanes are meant to be travelling in the direction they are pointed then any air resistance figures should also be of the front area of the plane regardless of the direction it is travelling. Assuming the plane is falling propellor first.

Ponciano

Danger

Gold Member
Huckleberry said:
True, but considering that airplanes are meant to be travelling in the direction they are pointed then any air resistance figures should also be of the front area of the plane regardless of the direction it is travelling.
An aeroplane is one of the only Earth-bound demonstrations of Relativity. Everything about a plane in the air is in reference to the air that surrounds it. Groundspeed is always calculated in regard to the airspeed, which is all that can be directly measured without using radar or lidar ground bounces. The whole point of wind vector triangles is to figure out in advance where you will be heading in relation to where you're travelling. (Heading and course are not the same thing in aviation.)

Huckleberry

I just meant that an aircraft that is flying straight will have air resistance on its front end, as will an aircraft that is falling straight down propellor first. It would make sense to list any numbers in the specs for air resistance based on the plane moving in a forward direction. It is the change in air pressure from forward motion that keeps the plane aloft.

In this problem the plane isn't moving any groundspeed at all, just lots of airspeed straight down. There is no curvature of the Earth to take into consideration, just the cliff.

Danger

Gold Member
Huckleberry said:
In this problem the plane isn't moving any groundspeed at all, just lots of airspeed straight down. There is no curvature of the Earth to take into consideration, just the cliff.
Sorry that I wasn't clearer in my post, Huck. I was agreeing with you. Even a plane falling off of a cliff has some groundspeed, even if it's zero or even negative. (I've seen a plane fly backwards in relation to the ground. Not a Harrier, mind you, but one that was flying with positive airspeed in a headwind strong enough to give it negative groundspeed.) What I was affirming was that the plane's movement is always in relation to the surrounding air, regardless of what direction it might be heading.

Huckleberry

Ok, gotcha. Guess I would fail BT's reading comprehension test. :tongue: Wind vectors definitely complicate things.

Danger

Gold Member
Huckleberry said:
Ok, gotcha. Guess I would fail BT's reading comprehension test. :tongue:
Somehow, I just can't see that as being a shortcoming. (Should he perhaps investigate a writing comprehension test?)
Okay, wrong forum for that. I don't know what kind of ships you were assigned to, but for some reason I got the impression of a carrier. If that's the case, then you probably have a few pilot friends and already have exposure to this. A wind vector triangle is essentially just a way to calculate which way you have to head in order to track in a certain direction. ie: If you want to fly straight north and have a wind from the north-west, you have to head north-north-west in order to track due north. That's way over-simplified, but gives the basic idea.

Vince

Thanks for the info guys, really appreciate it!

And Danger, I'm glad I helped you find an outlet to express yourself, though indirectly.

I'll try to dig up a clip of the scene and host it somewhere, if you guys are willing to analyze it.

Danger

Gold Member
Vince said:
And Danger, I'm glad I helped you find an outlet to express yourself, though indirectly.

I'll try to dig up a clip of the scene and host it somewhere, if you guys are willing to analyze it.
Again, thanks for that, and my apologies for the partial highjack of your thread. It would be great to see that. Please try to put it out in some format that is Mac-friendly and works on OS9. Otherwise, I'll have to try to find a video or DVD version.

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