[CaptainGyro]

I found a picture of the primary flight instruments of a U2, and thought some of you might be interested in what the pilot's seeing.

The top half of the screen (blue and pink) is the attitude and performance display, and the bottom half (black) is the nav display.

On the attitude display, the two tapes on the left and right are, respectively, airspeed and altitude. On the left tape he's showing an indicated airspeed of 102 knots, and at the bottom of the tape, a mach number of .700. On the right tape you can see that the altitude is 70,000.

There's no direct readout of true airspeed, but we can figure it out pretty easily from some indications on the lower nav display. At the bottom right you can see the number 398, with a small green arrow above it. The 398 is the ground speed, and the arrow indicates wind from that direction at 7 knots. That works out to about a five knot headwind, so true airspeed would be about 403.

The ground speed is confirmed by two numbers on the left side of the nav display. At the top left the distance to the next navigation waypoint is shown as 39.5 nautical miles. A little below that you can see that TTG (time to go) to that waypoint is 5:58. Do the math and the ground speed works out to 398, the same as we're seeing on the right.

The big difference between indicated and true airspeed is explained by the errors that are introduced into ram air sensing as altitude and airspeed increase. At low altitude and airspeed, indicated and true are very close, but as both increase, compressibility and low density combine to introduce errors that cause indicated airspeed to drift increasingly low. Nowadays we have air data computers that do all the math for us.

Mach number varies with temperature only, with the speed of sound decreasing as temperature decreases. At sea level on a standard day Mach 1 is about 660 knots; you can see that at his OAT (outside air temperature) it's about 576 (403 divided by .700).

By comparison, a modern airliner would be cruising at about 40,000', indicating about 250 knots, with a true airspeed of about 465 and mach .820.

 

[Charlie Petty]

Way cool. Wonder where he's headed.

That must be a very late version because I don't remember that much glass in a photo I saw long ago.

 

[Diamondback]

If memory serves the U-2 Coffin Corners at max altitude with a 98kt stall buffet and a 102kt Mach buffet.

A very demanding bird to get the most out of, one I'm glad I don't have to fight with.

 

[phantom4570]

That isn't Francis Gary Powers instrument panel Were the avionics and or the aerodynamics of the aircraft updated to assist the pilots with the coffin corners? I remember reading about the very small difference between stall and mach in this aircraft and wondering how any human could pilot one without crashing.

 

[Diamondback]

There isn't much room to change the aerodynamics, best they could do is refine the autopilot--but what hotshot ex-fighter jock (as all the early U-2 guys were) would choose a machine over hand-flying except while eating or taking a leak?

I suspect it's part of the U-2S "Senior Span" refit--the original right up to the 1980s TR-1s (the second and final reopening of the line) were all-steam-gauge if memory serves.

 

[CaptainGyro]

A narrow spread between stall buffet and mach buffet is only an issue in unstable air, where gusts can put you outside the envelope. At these altitudes, the air is pretty docile (partly because there isn't much of it.)

Also, excursions near the buffet margins are pretty easily dealt with by varying altitude...trading kinetic energy for potential, or vice-versa.

 

[Skeptic49]

I wonder how flying the U-2 compares with flying a very light aircraft, like a Citabria or 65 hp original Cub? Not much room in the envelope between maximum speed and stall and very susceptible to weather conditions.

Geoff
Who has a great respect for any good pilot of any good aircraft.

 

[CaptainGyro]

At cruise it's reputed to be a lot like a glider. At takeoff, however, the only thing it has in common with a rag-wing taildragger is a very short takeoff roll. After liftoff it looks like a rocket.

If you take a good look at the U2's profile from the side, you can see that it's a derivative of the F-104. I've seen one takeoff, and you watch in disbelief as that nose just keeps rotating up and up and up.

 

[TommyGunn]

If you take a good look at the U2's profile from the side, you can see that it's a derivative of the F-104. I've seen one takeoff, and you watch in disbelief as that nose just keeps rotating up and up and up.

:angel: Yes .... I do note a ....*slight* difference in the wings, though. :angel:

The Starfighter is one of those oldtime (if a jet CAN be "oldtime") jets that I have always liked .... sleek, elegant ..... even if the early models would eject the pilot down into the tarmac if he had to escape on a take off .....:shock:

 

[Diamondback]

Tony LeVier after the first flight described the original as "climbing like a homesick angel", and I'd bet with the bigger wing and better engine the R/S models (incl. TR-1 and ER-2, since redesignated U-2R and U-2ER respectively--the latter is a NASA special) are even faster to get up.

 

[Tim Burke]

At these altitudes, the air is pretty docile (partly because there isn't much of it.)

I've never before heard a lack of air described as a good thing...

 

[WaltGraham]

I've never before heard a lack of air described as a good thing...

You never met my ex-wife.

 

[Charlie Petty]

:!::!::!::!::!:

+1

 

[IrishCop]

You never met my ex-wife.

I saw what YOU did there, Walt. :rotflmao::rotflmao::rotflmao::bow::bow:

 

[IrishCop]

Mike, I got a look inside the cockpit of one of those back in '79...it impressed the hell outta me then.

So did the high calorie/high protein breakfast the flight crews got at zero-dark thirty in the chow hall before a flight (big steak, eggs, all the trimmings).

Hey, leave it to a fat man to notice the food...

 

[Diamondback]

If Skunk Works engineer Ben Rich is to be believed, it was not uncommon on long-haul Overflight missions to actually idle the engine for extended periods and operate as a de-facto jet-assisted glider to save fuel and extend range.

Sorry, Full Geek Mode here... Kelly Johnson was one of my boyhood heroes.

 

[Skeptic49]

The F-104 was my favorite fighter growing up. However, once I found out about it, not so impressive. In the end it was the bottom of the Hi-lo, NATO F-104s being 60% of a USAF F-4D. This led to the F-16 and F-15 combination for NATO.

Geoff
Who notes the short range and high mach being useful only for point defense over a friendly airfield, not to mention early models trading the gun for sidewinder electronics.

 

[Diamondback]

Bear in mind the time and role the Starfighter was designed for, too... it was designed as a knife-fighter, maximizing speed and maneuverability to fill the demands of combat pilots in Korea--Johnson flew over there during the war on a research tour asking the pilts what they wanted in a fighter to best the NoKo MiG-15s and distilled all of their requests into that.

In essence, the 104 was designed mainly to make a MiG-15 its jailhouse girlfriend, much like the Flanker was for the F-15 and in turn the F-22 was the Flanker. (And while the Flanker doesn't quite meet that stated design goal, it's still not a bird to underestimate in skilled hands.)

 

[WaltGraham]

(And while the Flanker doesn't quite meet that stated design goal, it's still not a bird to underestimate in skilled hands.)

"It ain't the arrows, it's the Indian"... although good arrows are a big plus...

 

[Skeptic49]

The last round of unclassified tests pretty much determined that stealth was best for survival with modern missiles flying around. One of the results was mass launch while closing and everybody dies.
Geoff
Who prefers a foxhole that doesn't attract so much attention.