Showing posts with label Mythbusters. Show all posts
Showing posts with label Mythbusters. Show all posts

Tuesday, June 16, 2009

Landing Large Planes on Carriers

I just finished reading Medusa's Child by John J. Nance. Decent aviation thriller, but the best part is the final scene.

WARNING: HERE BE SPOILERS!!!

In the final scene, the 727 is crippled and far out over the Atlantic, leaking fuel, and in the middle of a hurricane. Their only chance for survival is the USS Eisenhower, a Nimitz-class aircraft carrier. Under normal conditions an airliner cannot land on a carrier; this would happen. However, in the novel, the carrier steams at flank speed (35 mph, or closer to 40 if you take the 'neither confirmed nor denied' option) into 75+ mph hurricane winds, creating a 110+ mph winds over the deck. The stall speed of a 727 is somewhere around that figure, so the pilot just turns the plane into the wind and lands at just 5 mph over-deck speed.
I think that is an incredibly cool idea. However, landing any plane during a hurricane, much less a crippled airliner on an aircraft carrier, is pretty suicidal. However, in good weather, it still may be possible. The plane would come across at stall speed, and quickly decelerate. Although it takes a long way to land an airliner at an airport, they can land quickly, as well as take off quickly. Consider this quote from an xkcd blag post:

"A 747’s engines produce a quarter of a million pounds of thrust. That is, each engine is powerful enough to launch a brachiosaurus straight up". That amount of thrust, reversed, can stop an airliner real quickly.

I can't find any proof that anyone has actually landed an airliner on a carrier. There's a few videos on youtube, but all are very-slow-speed animations that don't seem realistic.

However, other large planes have been landed on carriers. The C-130, with a 132-ft wingspan (compared to 108 for the 727 and 196-225 ft for 747 variants), has been sucessfully landed on a carrier (video), and was even investigated as a COD (carrier on-board delivery aircraft). Even at full load, it could land with the props at full reverse and then takeoff from the same spot, with tailhook nor catapult.

The U-2 spy plane (wingspan: 103 ft) has also been used on a carrier. Even the U-2R, with a 40% wider wing, was also sucessfully landed on carrier, and they were even investigated as possible anti-ship missile carriers.
Wikipedia even has a picture.

Finally, although I can't track down examples of airliners flying into very high wind speeds, this thread has a discussion on flying light planes at near-zero speeds, and even backwards, at around 40mph stall speeds.

The verdict: plausible.

Saturday, September 20, 2008

Rockets update

So, I went out and flew a couple of rockets today, including a couple of untested birds:
  • Wizard: It's a real little rocket, no more than 10" long. I've flown it a couple of times before and this was no exception. It went about 300 feet on an A8-3 and landed safely, but it broke the tip off one fin. Nothing a little wood glue can't fix.

  • Cohete poquito: This little freak is basically a carved out dowel that holds a 13mm-diameter mini motor. A nose cone, launch lug, and a long thin dowel for stability are attached. It looks like a fireworks rocket. It flew well but mostly sideways on an A3-4T.

  • A boost glider. Nothing special, but I've been waiting forever to fly it. It angled a lot into the wind, but it's just something else to see a glider looping in the sky at sunset.

  • Rama, the cylindrical rocket, failed. When I tried to put the motor in, the engine mount crumpled.

  • 3M - Modified Mongoone Machbuster. Basically an Estes Mongoose 2-stage rocket shortened by 8 inches after an unfortunate encounter with the ground. (The extra tubing lives on as the body of the boost glider's pop pod)The bboster stage's motor moun and the upper stage launch lug failed simultaneously.

Despite the failures, it was a great launch.

I also bought 19 motors today:
6 Micromaxx (1/8A-1)
4 A3-4T
3 A8-3
3 B6-4
3 C6-0
Also, I got a SpaceShipOne scale model from Michaels for 11 bucks, so my next project is ahead of me. That and a clone of the Astron Invader - a UFO-shaped boost glider.

Friday, August 15, 2008

Can humans run a loop?

Well, partially. Here's how: For some strange reason, an object like a rollercoaster car must be dropped from 2.7 times the radius of the loop in order to complete the loop, as explained here. The instantaneous velocity of a falling object is (16t2)', or 32t. Since an object falls 16t2 ft in t seconds, h=16t2.
h=2.7r
v=32t
∴ 16t2=2.7r
t=v/32
∴ 16⋅v2/1024=2.7r
∴ 2.7r=v2/64
∴ r=v2/172.8
To convert from mph to fps, multiply by 22/15.
So... at 26.7 mph, the fastest recorded human speed, Maurice Greene can run around a loop over 17 feet high. If someone can hit 30 mph going down a hill, then they can make it around a 22 ft loop. Even an average joe chugging at 15 (down a ramp maybe?), then they can have a reasonable 11 ft loop. Those numbers are the diameter, by the way.Status: Plausible.

JUST KIDDING - I just found this - same idea and conclusion, but different (and correct) physics. Oops.