Brain teaser
12-08-2006, 03:55 PM
#123
Supporting Vendor
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I call 
on this one.
But it *was* funny.
on this one.But it *was* funny.
All right, we have a real world test.
I went in to my Airframes shop this morning and told a couple 2nd Class Petty Officers the I bet they couldn't erect a 100ft wide treadmill the entire length of the runway. They laughed and said "come back after lunch, sir."
<snip>
The three Mazda dealerships in town have been blacklisted.
The non-believers won't talk to me and are screaming about a conspiracy.
Popular Mechanics called and wanted to talk to the SeaBees about the runway they built, but they'd already disassembled it and had made a barbeque out of the engine they'd stolen.
I'm not allowed down in the Airframes shop anymore.
But at least i was right.
I went in to my Airframes shop this morning and told a couple 2nd Class Petty Officers the I bet they couldn't erect a 100ft wide treadmill the entire length of the runway. They laughed and said "come back after lunch, sir."
<snip>
The three Mazda dealerships in town have been blacklisted.
The non-believers won't talk to me and are screaming about a conspiracy.
Popular Mechanics called and wanted to talk to the SeaBees about the runway they built, but they'd already disassembled it and had made a barbeque out of the engine they'd stolen.
I'm not allowed down in the Airframes shop anymore.
But at least i was right.
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12-08-2006, 03:58 PM
#126
Boost Pope
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Well, I assume that there is *some* friction in the bearings, and some rolling resistance in the tires. But you're right in that a totally frictionless wheel and hub would result in the aircraft remaining stationary.
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12-08-2006, 04:03 PM
#127
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And as I realized that, I also realized that wheel speed isn't relevent. The comparative amount of friction is so low, it's not relevent either.
Perhaps a few of the other people who thought the plane would remain stationary will also understand that.
Perhaps a few of the other people who thought the plane would remain stationary will also understand that.
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12-08-2006, 04:08 PM
#129
Boost Pope
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12-08-2006, 04:11 PM
#130
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Join Date: Dec 2004
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Yeah, I realize that wheelspeed isn't relevant unless you don't have magical wheel bearings that can withstand such high speeds.
But, if there's one thing I learned, if you have magical conveyor belts, you have to have magical bearings...no ifs, ands or but(t)s.
Man, what I wouldn't give for a giant, remote-operated conveyor belt...underneath my house...with my house mounted on rollerblade wheels...then the house tied to a tree...then...
Okay, I'm done...for real...I promise...
I guess I keep writing because I'm trying to get the last word in before Philip swoops in here, gives some smart-*** comment and locks the thread
IBTL!!!! :gay:
But, if there's one thing I learned, if you have magical conveyor belts, you have to have magical bearings...no ifs, ands or but(t)s.
Man, what I wouldn't give for a giant, remote-operated conveyor belt...underneath my house...with my house mounted on rollerblade wheels...then the house tied to a tree...then...
Okay, I'm done...for real...I promise...
I guess I keep writing because I'm trying to get the last word in before Philip swoops in here, gives some smart-*** comment and locks the thread
IBTL!!!! :gay:
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12-09-2006, 02:12 PM
#137
Glad we have all come to aggrement on this one... 
I'll take you up on this one Olderguy
Are we talking about a magic current that increases in speed as the aircraft does, or is it just a normal very fast current?? The answer doesn't really matter, the results will be the same, just different magnitudes...
It will fly. The moving water will actually help the plane in the first part of the takeoff. The hardest part of a takeoff in a seaplane, from the airplanes perspective, is getting on step (planing out in boat speak or getting on top of the water in simple terms)
In pictures, from here:
to here:
Once the seaplane is on the step, very little of the float is actually touching the water (a foot on length or so) and it will accelerate to flying speed very quickly. The water moving the opposite direction to the floats will tend to slow the airplane, but it will also lift the float higher out of the water, thereby reducing drag. As airspeed increases, more and more of airplanes weight will be supported by the wing, reducing friction and allowing the plane to accelerate to flying speed.
I can illustrate with an example also. Cessna 172 seaplane, flaps to 20 degrees, full power will get airborne at just over 30 knots and fly in ground effect. With this treadmill example, at 30 knots for the seaplane the water will be moving at 60 knots. I could take the same airplane get it on step and let it accelerate to 60 knots on non moving water. Would not be a problem.
I will say though that being in a seaplane travelling across water that is moving at 60 knots would be quite a rough ride.....
cheers
I'll take you up on this one Olderguy
Are we talking about a magic current that increases in speed as the aircraft does, or is it just a normal very fast current?? The answer doesn't really matter, the results will be the same, just different magnitudes...It will fly. The moving water will actually help the plane in the first part of the takeoff. The hardest part of a takeoff in a seaplane, from the airplanes perspective, is getting on step (planing out in boat speak or getting on top of the water in simple terms)
In pictures, from here:
to here:
Once the seaplane is on the step, very little of the float is actually touching the water (a foot on length or so) and it will accelerate to flying speed very quickly. The water moving the opposite direction to the floats will tend to slow the airplane, but it will also lift the float higher out of the water, thereby reducing drag. As airspeed increases, more and more of airplanes weight will be supported by the wing, reducing friction and allowing the plane to accelerate to flying speed.
I can illustrate with an example also. Cessna 172 seaplane, flaps to 20 degrees, full power will get airborne at just over 30 knots and fly in ground effect. With this treadmill example, at 30 knots for the seaplane the water will be moving at 60 knots. I could take the same airplane get it on step and let it accelerate to 60 knots on non moving water. Would not be a problem.
I will say though that being in a seaplane travelling across water that is moving at 60 knots would be quite a rough ride.....
cheers
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