Question: Will the plane fly? (warning: nerdy)
01-30-2008, 11:33 PM
#241
Registered User
iTrader: (9)
Join Date: Jul 2007
Location: South Bay
Posts: 423
Car Info: '04 ed tuned vf39 jbp wagon
I kinda see it as a trick question. It doesn't mention how the plane is propelled or what the wind speed is.
For a plane to take off it needs to reach 1.5 times its stall speed. Stall speed is depenent on the relative air flow over the wing...that has nothing to do with the speed of the aircraft relative to the ground (aka the plane speed in relation to the conveyor belt speed under it).
Without reading the whole 12 pages of the thread, it seems like people are arguing over assumptions that aren't stated in the problem. If this was on one of my aerodynamics/aircraft dynamics tests back in college, the class would haved protested and received credit regardless of answer for a not enough info.
...my 2 cents
For a plane to take off it needs to reach 1.5 times its stall speed. Stall speed is depenent on the relative air flow over the wing...that has nothing to do with the speed of the aircraft relative to the ground (aka the plane speed in relation to the conveyor belt speed under it).
Without reading the whole 12 pages of the thread, it seems like people are arguing over assumptions that aren't stated in the problem. If this was on one of my aerodynamics/aircraft dynamics tests back in college, the class would haved protested and received credit regardless of answer for a not enough info.
...my 2 cents
Last edited by rubaCU; 01-30-2008 at 11:39 PM.
01-31-2008, 10:51 AM
#244
Registered User
iTrader: (12)
Join Date: Nov 2005
Location: Santa Clara
Posts: 3,522
Car Info: 2016 FXT
the wheels aren't propelling the plane, the engine is, so just because the wheels are moving twice as fast does not affect the plane taking off since the wheels are not powering the plane like they would on a car
01-31-2008, 11:00 AM
#245
250,000-mile Club President
Join Date: Nov 2002
Location: Bizerkeley
Posts: 4,770
Car Info: MBP 02 WRX wagon
The conveyor does not and cannot "counteract the movement", the wheels are idlers, they'll just spin faster-
The plane moves because of force applied to the atmosphere, not because of torque on the wheels- the plane IS moving at 150mph, the conveyor is moving at 150 mph, so if the plane had a wheel speed sensor it would say it was going 300, when in fact it is going 150.
Provided the stall speed of the plane is 100 mph or less, the plane will take off.
do you get it yet?
01-31-2008, 01:20 PM
#247
iClub Silver Vendor
iTrader: (25)
Join Date: Nov 2002
Location: Participating in some Anarchy!
Posts: 15,494
Car Info: 2005 LGT wagon
You are halfway to getting it right, but still missing the boat here.
The conveyor does not and cannot "counteract the movement", the wheels are idlers, they'll just spin faster-
The plane moves because of force applied to the atmosphere, not because of torque on the wheels- the plane IS moving at 150mph, the conveyor is moving at 150 mph, so if the plane had a wheel speed sensor it would say it was going 300, when in fact it is going 150.
Provided the stall speed of the plane is 100 mph or less, the plane will take off.
do you get it yet?
The conveyor does not and cannot "counteract the movement", the wheels are idlers, they'll just spin faster-
The plane moves because of force applied to the atmosphere, not because of torque on the wheels- the plane IS moving at 150mph, the conveyor is moving at 150 mph, so if the plane had a wheel speed sensor it would say it was going 300, when in fact it is going 150.
Provided the stall speed of the plane is 100 mph or less, the plane will take off.
do you get it yet?
What about head/tail wind?
Aaaaaaahhhhhhhhhhhhhhhhhhh!!!!!!!!!!!!!!!!!
01-31-2008, 02:48 PM
#248
Registered User
iTrader: (11)
Join Date: Mar 2006
Location: San Francisco
Posts: 1,075
Car Info: 05 WRB STi
Ya it made sense after the diagram. The speed of the treadmill would never matter. It could move at 1000mph opposite of the plane and all that would happen is the wheels would spin faster. The plane would continue to move forward regardless.
I was right in thinking the plane would need some forward speed to take off.
I was wrong in thinking the treadmill would make a difference.
I was right in thinking the plane would need some forward speed to take off.
I was wrong in thinking the treadmill would make a difference.
01-31-2008, 05:16 PM
#249
VIP Member
iTrader: (7)
Join Date: Jun 2003
Location: Funtown
Posts: 25,095
Car Info: A limousine with a chauffer
this entire thread was rendered useless by the 1980's:
http://www.youtube.com/watch?v=RrpJmNRrVHI
http://www.youtube.com/watch?v=RrpJmNRrVHI
Thread
Thread Starter
Forum
Replies
Last Post
nachomc
Sacramento & Reno
26
09-07-2006 08:32 AM