Quick U2 Question

Hey all, im sure this is one all of you can answer, but i was always wondering why do the wheels on the wings of the U2 fall off after it takes off and how does it land again w/o them .. was watching a history channel thing bout the U2 and i noticed that the wheels fly off (not the main ones) on takeoff.. any links to explain this?

They are not permanently attached to the wings. They are there only to support the wings which stretch out so far from the fuselage that if left alone, they would be touching the ground, imagine what would happen if they touched the ground durring takeoff.
The reason why they are temporary, is that they would cause too much drag on the wings as the U2 reached supersonic speed.

A good site for research would be:home.cfl.rr.com...
hope this helps.

Hmm I agree they are for support, but I was wondering if its needed for takoff, then id imagine that it would need it to land right?

Originally posted by RealisticPatriot
Hmm I agree they are for support, but I was wondering if its needed for takoff, then id imagine that it would need it to land right?

No, it drags its wingtips to slow it down (in conjunction with brakes of course). The wingtips are built up for it and are replaced on a regular basis.

Originally posted by COOL HAND

Originally posted by RealisticPatriot
Hmm I agree they are for support, but I was wondering if its needed for takoff, then id imagine that it would need it to land right?

No, it drags its wingtips to slow it down (in conjunction with brakes of course). The wingtips are built up for it and are replaced on a regular basis.

Dang it Cool hand , you beat me to the punch

Cool Hand your insane, the reason the U2 does not need the wing tip carriages upon landing is A. the lift induced on the wing when it is in the air keeps the wing tip "up" and B. The weight of the "take off" fuel in no longer in the wing tanks, thereby decreasing the "weight" of the wings and decreasing the amount of downward deflection induced at the wing tips. When the U2 lands it is chased by a special carriage truck that helps stabalize the aircraft once its rolling speed is under 40mph (I believe).

Also the U2 is not supersonic.


www.fas.org...

www.jamesshuggins.com...

www2.acc.af.mil...

Above are pictures from a U2 landing, do you see the wing tips touching the ground ???? I dont think so.

Nope, sorry, the plan was not built to (intentionally) drag the wing tips. They reinforcement at the wing tip is in the case of an emergancy landing with fuel on board.

[edit on 3-8-2004 by robertfenix]

[edit on 3-8-2004 by robertfenix]

robertfenix please dont insult other members.

Actually, Cool Hand is right, when the U2 lands, it DOES drag a tip of the wing over the ground.
The chase truck only helps the pilot to land, by giving the pilot instructions, it is not a carriage truck, or whatever you mean.

Originally posted by robertfenix
Cool Hand your insane, the reason the U2 does not need the wing tip carriages upon landing is A. the lift induced on the wing when it is in the air keeps the wing tip "up" and B. The weight of the "take off" fuel in no longer in the wing tanks, thereby decreasing the "weight" of the wings and decreasing the amount of downward deflection induced at the wing tips. When the U2 lands it is chased by a special carriage truck that helps stabalize the aircraft once its rolling speed is under 40mph (I believe).

Also the U2 is not supersonic.

Robert, oops my bad, was thinking of the SR71 (worked arond them a few years while in korea). my bad. good catch!

Zion, please show me anywhere, anything, any sort of support you can come up with that says the U2 was DESIGNED to land by draging the wingtips across the tarmac.

And then I will stand corrected, but I should remind you that I have seen with my own two eyes a U2 land in front of me.

Nice, thank you for the points deduction, I am glad to see that there are some people who would rather have people mislead by incorrect information then to have the real truth.


[edit on 3-8-2004 by robertfenix]

Originally posted by robertfenix
Zion, please show me anywhere, anything, any sort of support you can come up with that says the U2 was DESIGNED to land by draging the wingtips across the tarmac.

And then I will stand corrected, but I should remind you that I have seen with my own two eyes a U2 land in front of me.

Nice, thank you for the points deduction, I am glad to see that there are some people who would rather have people mislead by incorrect information then to have the real truth.


[edit on 3-8-2004 by robertfenix]

You want the truth, here is a quote from a U2 pilot on how he lands his aircraft:

LINKY

Feel free to apolgize at any time Robert.

I'm sure any points deduction was for this...

Cool Hand your insane

Not for your info...which is largely correct with Zion's additions....

Hmm...the U2 landing without any support at the wings looks SO unstable like it can just tip to one side at any time. You said you saw a U2 land. I imagine you didnt see it have any sort of tipping problem.. even while taxiing?

Originally posted by RealisticPatriot
Hmm...the U2 landing without any support at the wings looks SO unstable like it can just tip to one side at any time. You said you saw a U2 land. I imagine you didnt see it have any sort of tipping problem.. even while taxiing?

After it comes to a stop, they reattach the pogo wheels to the wings and it can taxi like any other plane. Check the link I provided above, it should answer all your questions. If not then try this one:

ANOTHER LINKY

Hope this helps.

Of course I'm right! I'm always right!

usmilitary.about.com...
The team still had to recover the U-2. Not an easy task in a sandstorm. With its long wings, the plane is tough to land on a calm day. Plus it must land on two centerline wheels and coast to a stop. Then it gently drops onto one of its two wing skids.

It has special skids underneath the wing


www.donhollway.com...
The only research Powers and the rest were doing was in stretching the U-2’s envelope. In thin stratospheric air the margin between its top and stall speeds amounted to just a few knots, known to the pilots as the “coffin corner.” The J57, capable of just 6% of its sea-level thrust, became susceptible to flameouts, necessitating a 30,000-foot dive to achieve a restart. And all that lift made the plane reluctant to land; it tended to porpoise just above runway unless the pilot put it into a stall. Then, unless he’d perfectly balanced his fuel load, the plane would tip over on its bicycle landing gear, dig in one of the wingtip skids and ground-loop.

Feel free to apolgize at any time Robert.

thats all, very informative... Thanks for answering my Q

I thught this was about the band, doh

Originally posted by RealisticPatriot
Hey all, im sure this is one all of you can answer, but i was always wondering why do the wheels on the wings of the U2 fall off after it takes off and how does it land again w/o them .. was watching a history channel thing bout the U2 and i noticed that the wheels fly off (not the main ones) on takeoff.. any links to explain this?

Landing they were designed to come down hard in soviet territory.

I am a glider pilot and it may be worthwhile to take a look at it from the glider perspective. Althought I am not that an experienced a glider pilot I have noticed that some motor gliders take off without anyone on the wing and let it drag along the runway.

Equally so when landing bear in mind that most if not almost all gliders have no wing wheels and when landing you just try to keep the wings level and then when you slow you can generally keep the wings level even sometimes well into a stop. Then one wing falls and touches the ground. Even if one does hit whilst moving then the ends are slightly reinforced.

Ok I realise that this is for gliders and it may not apply here but the principle is the same....I cannot see any reason why the U2 can't do the same. I mean it would land on a runway anyway (smooth so less chance of a wing sticking in the ground) and we land on grass!

Originally posted by Zion Mainframe
Of course I'm right! I'm always right!

Plus it must land on two centerline wheels and coast to a stop. Then it gently drops onto one of its two wing skids.

Feel free to apolgize at any time Robert.

Try reading next time, .... Land on two centerline wheels and coast to a STOP. THEN it gently drops onto one of its two wing skids.

They DID NOT design the aircraft to intentionally have the wing tips make contact with the tarmac while rolling, hence the comment that the aircraft was prone to GROUND LOOPS. Do you know what that is ? Do you know how much damage that cause to the airframe of a U2 ? A ground loop is not something good.

The wings of a U2 are held up by the ground cushion of air at speed, once the aircraft drops below 40mph of ground speed the wings begins to sag down. But 99% the U2 pilots were capable of bringing the aircraft to a full stop on the main carriage without the wing tips dragging. The tilt over is an at rest position until ground crew arrive at the aircraft and reattach the wing trolleys

No apology will be given.

"The chase truck only helps the pilot to land, by giving the pilot instructions, it is not a carriage truck, or whatever you mean."

Gee, I guess the ride I took in the back of an El Camino at Beale AFB back in the eighties where we 'caught' the wing of a U-2 was just a figment of my imagination. That, or maybe it was a TR-1 (he said, while scatching his head)

At home station-where they have the "carriage vehicle" they use them. I have never personally seen one in operation at a deployed location.


"They are not permanently attached to the wings. They are there only to support the wings which stretch out so far from the fuselage that if left alone, they would be touching the ground, imagine what would happen if they touched the ground durring takeoff.
The reason why they are temporary, is that they would cause too much drag on the wings as the U2 reached supersonic speed."

Uh, supersonic?... Nevermind.

www.blackbirds.net...


The pilot needs to stall the aircraft from about two feet, to get it on the ground. But more on that later.

long wingspan and its "desire" to keep flying (even with idle power),

By stalling I mean to cause the aircraft's wings to stop generating lift.

As it slows, the tailwheel lowers to the runway and when the U-2 reaches a stall, the main wheel touches down. The maneuver looks graceful to onlookers, but tends to feel violent inside the cockpit as the pilot feels the stall, touches down and struggles to keep the wings level. But, it is not over yet. The pilot still has to "fly" the wings until the aircraft can stop. Remember, the pogos fell out upon takeoff so as long as the airplane is rolling and the wings are producing some lift, the pilot must fly the wings to keep them off the runway.

the pilot must fly the wings to keep them off the runway.

Finally, as the aircraft begins to stop, the pilot will gently put one wing on the ground.


Here are some excerpts from the link you provided, I am sure you will find it clearly stated that the pilot must continue to "fly" the wings while the aircraft is on the ground. See above... the pilot must fly the wings to KEEP THEM OFF THE RUNWAY.

The U2 must Stall two feet above the runway because the amount of lift generated by the wings even at slow speed is enought to keep the aircraft airborne. By stalling it forces the rear of the fuselage to break the aircushion thereby allieviating some of the lift being generated and allows the aircraft to slam onto the runway. From the observation of the ground it looks like the U2 makes a soft "drop" onto the runway.

Oh here is another quote from an Air Force Technolofy website

www.airforce-technology.com...

The wings are fitted with titanium skidplates so that when the aircraft lands and is brought to a HALT, the wing can gently touch the ground.


[edit on 4-8-2004 by robertfenix]