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 Post subject: Flying the U2 to the edge of space
PostPosted: 02 Mar 2014, 09:34 
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Nice article on the BBC web site

http://www.bbc.com/future/story/2014022 ... e-of-space


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 Post subject: Re: Flying the U2 to the edge of space
PostPosted: 02 Mar 2014, 10:26 
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That was a great article.

I used to fly as SIC two of the 5 lear 28's and can relate to just a tiny bit of high altitude challenges. The 28's are a 25 series lear fitted (as a test bed) with the 55 wing. They were certified to 510 and we regularly flew them there. It was actually difficult and a bit scary to get them back down from up there. You couldn't move the controls, you just put your hand on them and "thought" about what you wanted it to do. The old "JET" A/P ("just enough technology") wasn't good enough to fly a descent so you had to disconnect it (and hope the plane wasn't too far out of trim). Then you brought the power back just a tiny bit while closely watching the pressurization. These planes held the cabin at full power but they'd start losing the cabin (the cabin altitude would climb - this is the opposite of what you want when you descend) when we pulled power back. It was a fine line between getting down and not sending the cabin climb rate too high or letting the cabin altitude get above 10K (plus, soon the PAX ears are going to transition from a climb to a descent and they won't be happy if you let either get above 500FPM). Spoilers were either ON or OFF and deploying them up there meant a rough ride for the PAX and a handful to fly. At 510 the plane was up against the barberpole and MMO so leaving the power up and pushing the nose over wasn't an option either. Lastly, to make things a little more challenging, you hated to come down early because they burn so much fuel down low and you hated to stay up too long because it was hard to get down (at least until you got to 450 and below) quickly.

I'm glad I got to see that stuff but I wouldn't do anything like that these days....

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 Post subject: Re: Flying the U2 to the edge of space
PostPosted: 02 Mar 2014, 11:01 
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That was fascinating to read.

John, it sounds like the Lear was equivalently pressurized to the U2 if you were are 10,000 PA at 51,000 and the U2 is at 29,000 feet at 70,000? I wonder what it would take in terms of fuselage strength to build a plane that had a 10k PA at 70,000?

In the movie fantasy there are lots of military space vehicles. I suppose, from reading the article, that there are no practical military applications for vehicles at the edge of space like this - excepting the present mission?

When you flew the Lear was it as a test pilot or where those planes in private service? What was the mission and why did the program not survive? I think that story might be as/more interesting than the U2.

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 Post subject: Re: Flying the U2 to the edge of space
PostPosted: 02 Mar 2014, 13:24 
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One minor nit with the story. Pilots are required to wear pressure suits when flying above 50,000 ft. However the Armstrong line is at 63,000.

Username Protected wrote:


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 Post subject: Re: Flying the U2 to the edge of space
PostPosted: 02 Mar 2014, 13:38 
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A lot of older airplanes have so many small leaks in the pressure hull that it can be difficult to descend from any altitude at idle thrust without the cabin climbing. We had a couple of MD-80's many years ago that required a different descent profile in order for the cabin to descend. Otherwise, pulling the throttles to idle would cause cabin to climb in excess of 500 fpm.


Username Protected wrote:
That was a great article.

I used to fly as SIC two of the 5 lear 28's and can relate to just a tiny bit of high altitude challenges. The 28's are a 25 series lear fitted (as a test bed) with the 55 wing. They were certified to 510 and we regularly flew them there. It was actually difficult and a bit scary to get them back down from up there. You couldn't move the controls, you just put your hand on them and "thought" about what you wanted it to do. The old "JET" A/P ("just enough technology") wasn't good enough to fly a descent so you had to disconnect it (and hope the plane wasn't too far out of trim). Then you brought the power back just a tiny bit while closely watching the pressurization. These planes held the cabin at full power but they'd start losing the cabin (the cabin altitude would climb - this is the opposite of what you want when you descend) when we pulled power back. It was a fine line between getting down and not sending the cabin climb rate too high or letting the cabin altitude get above 10K (plus, soon the PAX ears are going to transition from a climb to a descent and they won't be happy if you let either get above 500FPM). Spoilers were either ON or OFF and deploying them up there meant a rough ride for the PAX and a handful to fly. At 510 the plane was up against the barberpole and MMO so leaving the power up and pushing the nose over wasn't an option either. Lastly, to make things a little more challenging, you hated to come down early because they burn so much fuel down low and you hated to stay up too long because it was hard to get down (at least until you got to 450 and below) quickly.

I'm glad I got to see that stuff but I wouldn't do anything like that these days....


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 Post subject: Re: Flying the U2 to the edge of space
PostPosted: 02 Mar 2014, 14:39 
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Tony,

The company I worked for was your basic rent-a-Lear charter service and management co. We had bases in Chicago UGN and Aspen and flew between them often. Getting a 20 series Lear to make Chicago-aspen in the winter is usually tough. Going to 510, the winds tend to die down above the trop-height. (Trop=tropopause, the point where it no longer gets (much) colder as you go higher.).

Oh and to dispel the rumors; No, it is not darker up there and No, you can't see the curvature of the earth. It looks pretty much like it does in the 40's....

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 Post subject: Re: Flying the U2 to the edge of space
PostPosted: 02 Mar 2014, 15:16 
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If one is fortunate enough to be in a cockpit above fl 450 try this experiment. Take a straight edge such as a ruler or even a stiff sheet of paper and hold it fairly close to the eye and place each end of the straight edge on the horizon and then notice where the horizon is in the middle of the straight edge.

The sky takes on a dark blue hue at those altitudes.


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 Post subject: Re: Flying the U2 to the edge of space
PostPosted: 02 Mar 2014, 17:22 
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Lars came into the program after I had left to go fly a desk :tongue: . so we haven't met to date. Good article. The long flights were LONG. The first six hours were the hardest for me, then it was sort of mental after that in that the flight was over half over. Most high flights tended to be 9 hours but have increased over the years.

The plane's autopilot was trimmed to fly at high altitude and worked quite well. One could roll right into 45 degrees of bank and turn without a problem. Since the U-2 is only stressed for 2 g's, that was pretty much our max angle used. But being optimized for high altitude (and low indicated airspeed, less than 100) meant that it was unusable down low, so all flying once you clicked off the autopilot to come down was by hand. Fairly high workload flying an approach in the weather. And it got worse when it came time to land.

We've had several of our U-2 guys go through TPS. One of them was Mike Masucci, who was one of the pilots on the Virgin Atlantic SS2:

http://news.cnet.com/8301-11386_3-57617 ... st-flight/

But the view was great! Never any clouds at altitude. I never got tired of looking outside (unless it was completely overcast). You did have to watch fuel, as was mentioned above, as we had great range up high but once we got down, we had very few options as to where we could land. It better be someplace near where you were planning to land as the fuel usage climbed dramatically when cruising around at vectoring altitudes. High fuel flow and slow speed. Slower than a Bo most of the time.


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 Post subject: Re: Flying the U2 to the edge of space
PostPosted: 02 Mar 2014, 23:16 
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Username Protected wrote:
Fairly high workload flying an approach in the weather. And it got worse when it came time to land.


That makes Mike Hua's dead stick landing at night in the middle of nowhere even more impressive.

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 Post subject: Re: Flying the U2 to the edge of space
PostPosted: 03 Mar 2014, 02:51 
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The greatest feats of U-2 flying in my opinion (not taking anything away from Hua) have been instances of runaway full nose down trim. We've had that happen three times that I know of. The first was to Johnathan George. He just retired as a one star. At altitude his trim went full nose down. He had to use both arms to pull back on the yoke to keep it from nosing over. He wanted to eject but was afraid the negative g's would prevent him from reaching the ejection handle on the seat between his legs. He maintained that back pressure (about 30-40 pounds) for the over an hour it took to descend from altitude then had to make a no flap landing. No Flaps in the U-2 are extremely hard to do as you have to precisely control your airspeed just 2-3 knots above a stall on a two mile, 1/2 degree glideslope. Doing that while fatigued from holding the back pressure is quite remarkable. He had to be helped out of the aircraft by the fire department after he landed because he didn't have any strength left in his arms.

http://en.wikipedia.org/wiki/Jonathan_D._George

He was awarded the Kolligian Trophy for the outstanding flight in the AF that year.

It just recently happened to Joe “Tucc” Santucci, who also received the same award.

http://www.usni.org/u-2s-still-flying-high

Bruce Cucuel also had it happen to him when he was in a two seat "B" model.

Fine pilots all!


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 Post subject: Re: Flying the U2 to the edge of space
PostPosted: 03 Mar 2014, 14:47 
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Username Protected wrote:
The greatest feats of U-2 flying in my opinion (not taking anything away from Hua) have been instances of runaway full nose down trim. We've had that happen three times that I know of. The first was to Johnathan George. He just retired as a one star. At altitude his trim went full nose down. He had to use both arms to pull back on the yoke to keep it from nosing over. He wanted to eject but was afraid the negative g's would prevent him from reaching the ejection handle on the seat between his legs. He maintained that back pressure (about 30-40 pounds) for the over an hour it took to descend from altitude then had to make a no flap landing. No Flaps in the U-2 are extremely hard to do as you have to precisely control your airspeed just 2-3 knots above a stall on a two mile, 1/2 degree glideslope. Doing that while fatigued from holding the back pressure is quite remarkable. He had to be helped out of the aircraft by the fire department after he landed because he didn't have any strength left in his arms.

http://en.wikipedia.org/wiki/Jonathan_D._George

He was awarded the Kolligian Trophy for the outstanding flight in the AF that year.

It just recently happened to Joe “Tucc” Santucci, who also received the same award.

http://www.usni.org/u-2s-still-flying-high

Bruce Cucuel also had it happen to him when he was in a two seat "B" model.

Fine pilots all!

Amazing. That had to be agonizing.

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 Post subject: Re: Flying the U2 to the edge of space
PostPosted: 08 Jun 2018, 10:03 
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Interesting article on the continued operation of this great aircraft. (Might be behind the wsj paywall).

https://www.wsj.com/articles/the-u-2-sp ... 1528382700

Airframes and engines get a full OH every 6 years. Still using film cameras, with a 250 lb load of film.

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 Post subject: Re: Flying the U2 to the edge of space
PostPosted: 08 Jun 2018, 10:19 
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A retired U2 pilot that I know says that wet film is still the gold standard in photo reconnaissance. Digital has not yet gotten the highest resolution that film has.

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 Post subject: Re: Flying the U2 to the edge of space
PostPosted: 08 Jun 2018, 22:16 
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A retired U2 pilot that I know says that wet film is still the gold standard in photo reconnaissance. Digital has not yet gotten the highest resolution that film has.

Depends on the circumstances. Image quality and detail depends on more than pure resolution. Dynamic range and signal to noise ratio of the best solid state imagers is better than film and both impact detail.

70mm film is hard to beat for image quality at 20+ frames/sec but that could probably be duplicated with multiple imagers and fancy optics.

I wonder what the film width and image rate is for the U2 cameras?

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 Post subject: Re: Flying the U2 to the edge of space
PostPosted: 08 Jun 2018, 23:51 
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Username Protected wrote:
That was a great article.

I used to fly as SIC two of the 5 lear 28's and can relate to just a tiny bit of high altitude challenges. The 28's are a 25 series lear fitted (as a test bed) with the 55 wing. They were certified to 510 and we regularly flew them there. It was actually difficult and a bit scary to get them back down from up there. You couldn't move the controls, you just put your hand on them and "thought" about what you wanted it to do. The old "JET" A/P ("just enough technology") wasn't good enough to fly a descent so you had to disconnect it (and hope the plane wasn't too far out of trim). Then you brought the power back just a tiny bit while closely watching the pressurization. These planes held the cabin at full power but they'd start losing the cabin (the cabin altitude would climb - this is the opposite of what you want when you descend) when we pulled power back. It was a fine line between getting down and not sending the cabin climb rate too high or letting the cabin altitude get above 10K (plus, soon the PAX ears are going to transition from a climb to a descent and they won't be happy if you let either get above 500FPM). Spoilers were either ON or OFF and deploying them up there meant a rough ride for the PAX and a handful to fly. At 510 the plane was up against the barberpole and MMO so leaving the power up and pushing the nose over wasn't an option either. Lastly, to make things a little more challenging, you hated to come down early because they burn so much fuel down low and you hated to stay up too long because it was hard to get down (at least until you got to 450 and below) quickly.

I'm glad I got to see that stuff but I wouldn't do anything like that these days....


John,

I concur with your observations of FL510 in the Lear. I flew a 25D for a few trips, and decided to see how it did at FL510. What I learned was that I had no business being up there in that plane for the reasons you stated.

My hat's off to the U2 pilots, superb airmen all. :bow:


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