To protect the craft during the 6.7 Mach flight, there was a coating sprayed on the body of the X-15. As it burnt off, it would cloud the view of the pilot, Air Force Major Robert White in this case.
One small correction - the pilot for the M6.7 flight was Major Pete Knight. The highest mach that Major White got to was M6.04. See:
Airbus was conducting trials many years ago with a covering that was striated like shark skin. They measured small drag reductions, but I haven't read anything about the concept in recent years. I suspect Airbus found that it was hard to keep the surface maintained properly.
During a portion of the boost, the flight director display was inoperative, however the pilot continued the planned trajectory referencing the external horizon.
This failure is somewhat reminiscent of Pete Knight's experience on flight 184 of the X-15 program. The X-15 had a complete electrical failure as it climbed steeply through about 104,000 ft. The engine shutdown and all flight control was lost, as both Auxiliary Power Units had failed, and they provided power for the hydraulic pumps. Fortunately the altitude peaked out low enough that there was enough aerodynamic pressure to keep the nose pointed in roughly the right direction.
He managed to get one APU running again, so he had power for the flight controls. But he still didn't have flight instruments. He knew he needed to pull to a fairly high angle of attack (AOA) to make a successful reentry, but if he pulled to too high an AOA the vehicle would lose directional stability. So he increased the AOA until he saw the nose start to slice off to the side, then decreased the AOA to regain control. He milked the AOA until he could see visually that his dive angle had decreased enough that he knew he had successfully reentered the atmosphere. Then he landed on one of the many dry lakes to the NW of Edwards.
I certainly don't want to take away from Mike Melville's skill, as he is a very accomplished test pilot. He has had the opportunity to fly many oddball aircraft in his many years as a test pilot with Burt Rutan.
Yup, that would definitely be a boom for the air data system and angle of attack and sideslip probes. It is a very standard thing to see on flight test vehicles. You need to get that stuff well away from the rest of the aircraft so they are not affected by the flow field around the vehicle. After a bunch of flight testing you figure out how the flow field affects the accuracy of the production air data and angle of attack probes, which are mounted on the vehicle itself. So the production vehicle doesn't need the nose boom. But it is needed until they have enough data to calibrate the production probes.
But if I were doing a scientific or engineering paper, I would not use Excel.
Well, engineering is about actually getting some work done, not doing scientific papers. That is technical publishing, and I agree that Excel would be a poor choice there. But I concur that it is a great choice for quick and dirty calculations.
Re:Mach Freakin' 5 - make that mach freakin' 7-10
on
NASA Tests X-43A
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· Score: 1
Don't pay too much attention to that Google conversion from Mach to speed. It only works if the temperature is 15 deg C (i.e. sea level under the International Standard Atmosphere). The speed of sound varies with the square root of the temperature, and it is a lot colder up where the X-43 was flying than it is at sea level, so the speed of sound is slower.
Mach 7 at sea level is about 8575 km/h, but Mach 7 at 100,000 ft it is only about 7615 km/h ( assuming the mythical day with standard temperature at both altitudes).
Re:Mach? What is that?
on
NASA Tests X-43A
·
· Score: 2, Informative
Mach is a measure of speed in relation to the speed of sound (Vs). (Vs) varies with Temperature (t), and is calculated as such:
Vs = 332 + 0.6 * t
(Where Vs is in Meters/Sec, and t is in ^C)
The above equation is a very crude linearization, that only gives close to the right answer. The speed of sound is actually proportional to the square root of the temperature.
a = SQRT(1.4*286.99*T)
(Where a = speed of sound in m/s, 286.9 is the gas constant for air and T is the temperature in degrees Kelvin)
There's no way they could provide coverage like this in an area with a lot of high-rises. The people on the far side of the building would have horrible reception.
Do you lose cell phone coverage when you walk around the other side of a high-rise? I sure don't. They've learned how many antennae they need to install to provide seamless coverage. Why do you think they haven't done the same thing with this wireless broadband?
Actually 3700 flight hours is fairly small for a plane of this age. Most commercial planes have a 20,000 operating hour overhaul schedule.
Apparently the F/A-18A was designed for a 6,000 hr life, assuming a particular load spectrum that the Navy specified. There was a fair bit of air combat manoeuvring (ACM) included in that load spectrum, but they also assumed quite a bit of straight and level, 1g flight while transiting to and from ACM training areas. The USN training areas are typically off-shore, so there is a fair bit of transit time in any given ACM training mission, so the percentage of time at high g is fairly low.
Canada was shopping for multi-role fighters a couple of decades ago, and Canada was looking for an aircraft with an 8,000 hr life. The Canadian ACM training areas are very close to the fighter bases, so there is only a few minutes of transit time at each end of an ACM mission, which means a higher percentage of the time is spent at high g. McDonnell Douglas said the F-18 would meet the Canadian life spec, and they won the contract.
Canada started finding major airframe cracks a few years after the jets went into service. Some of the jets that had seen a lot of ACM were found to be near the end of their useful life with only around 2,000 hrs on the airframe. Canada had to do some major airframe overhauls, replace some of the major fuselage bulkheads, and adding reinforcements.
If this jet spent a long time with the Blue Angels, it might be at the end of its useful life.
Many people somehow think that Polly Vacher's flight around the world is better planned and organized than Jon Johanson's trip.
She, like Jon Johanson, had made sure that fuel was available at all her
planned stops, but she did not make sure that fuel was available at all
possible diversion airfields (the list of planned legs on her web site shows
that McMurdo was a planned fuel stop).
She, like Jon Johanson, ran into higher than expected winds over Antartica,
and had to divert. She, like Jon Johanson, diverted to an airfield that did
not have fuel for her (she went back to her destination, but she had already
used all the fuel in her fuel cache).
Re:crusing at or above mach 1 not so unusual
on
Son of Concorde
·
· Score: 1
I'm pretty sure that f-15's can cruise at or slightly above mach2 and the russians had a mig that could cruise at mach 3...
You seem to have a different definition of cruise than most people. The F-15 (and any other aircraft except the Concorde and SR-71 and its ilk) would need to use afterburner to sustain Mach 2, so it would be burning a lot of fuel, and could only sustain this condition for a short period. I wouldn't call this cruising. Cruising implies that the condition can be sustained for a long period, which pretty much means without the use of afterburners.
The SR-71 and its kin are a special case. The J-58 engine has several large ducts that allow air to go from the 4th stage of the compressor to the front of the afterburner, bypassing the aft stages of the compressor, the combustion chamber and the turbine. The engine is sort of acting as a ram jet at the design cruise condition. The bypass ducts are needed because the compressor inlet temperature is extremely high at the design Mach number. The air temperature gets even higher as you compress it, and even higher once you burn the fuel in the combustion chamber. But the turbine can only tolerate air at a certain temperature, so that naturally causes a problem. A ram jet would work, but they only generate usable thrust once you are moving quite fast. So the J-58 operates as a conventional turbo-jet at low speed, and then the bypass valves are opened up at high speed, converting it to sort of a ram jet cycle.
Concorde cruised without afterburner.
on
Son of Concorde
·
· Score: 2, Informative
Until very recently every plane that flew above Mach 1 had to do it while on afterburners...
Actually, the concorde cruised at Mach 2 without afterburners. The afterburners were used for take-off, the acceleration from subsonic to M1.70, and then they were not needed for speeds above M1.7. This is documented in quite a few books about Concorde.
They didn't call it supercruise though, as that is a marketing buzz word developed recently to help sell fighters. There is no maqic about supercruise - it is just a matter of having an efficient intake system that decelerates the air to subsonic speed going into the engine, and an efficient nozzle system to accelerte the exhaust to supersonic speed so you can get net positive thrust.
The largest gun ever used was constructed by Nazi Germany and had an effective range of less than 30 kilometers (and that's horizontal distance, it couldn't have got that far up).
Actually, the Germans had a gun in 1918 that had a range of about 130 km. "From March through August of 1918, three of the guns shot 351 shells at Paris from the woods of Crepy, killing 256 and wounding 620." See: http://www.astronautix.com/lvs/parisgun.htm.
The way I figure it, the guys making the large bids are lawyers hoping to get the seller's business when he is sued by Apple. The lawyer who buys the song will likely get a pretty good return on his investment.
"The X-15 reached space -- that has been confirmed over and over. A slightly better, more modern X-15 could reach LEO"
The X-15 reached space for a few minutes at a time in a ballistic parabola. It's a big leap from a sub-orbital lob to going into orbit.
Sure, a super X-15 derivative might be able to reach LEO, but getting back would be a trick. Titanium isn't going to cut it due to greatly increased energy to be dissipated.
Pete Knight reached a top speed of about 4520 mph in X-15 #2 and there was enough structural damage from the heat that it never flew again. Orbital velocity is about 17,500 mph, or about 15 times the kinetic energy as 4520 mph.
Slashdot Mirror
To protect the craft during the 6.7 Mach flight, there was a coating sprayed on the body of the X-15. As it burnt off, it would cloud the view of the pilot, Air Force Major Robert White in this case.
One small correction - the pilot for the M6.7 flight was Major Pete Knight. The highest mach that Major White got to was M6.04. See:
http://www.edwards.af.mil/history/docs_html/aircra ft/x-15_mach6.7.html / log.html
http://www.hq.nasa.gov/office/pao/History/x15conf
Airbus was conducting trials many years ago with a covering that was striated like shark skin. They measured small drag reductions, but I haven't read anything about the concept in recent years. I suspect Airbus found that it was hard to keep the surface maintained properly.
http://www.spc.org.nc/coastfish/News/Fish_News/84/ Shark-skin-planes.htm u scano/Applications.htm
http://www.bio.davidson.edu/Courses/anphys/2000/T
During a portion of the boost, the flight director display was inoperative, however the pilot continued the planned trajectory referencing the external horizon.
This failure is somewhat reminiscent of Pete Knight's experience on flight 184 of the X-15 program. The X-15 had a complete electrical failure as it climbed steeply through about 104,000 ft. The engine shutdown and all flight control was lost, as both Auxiliary Power Units had failed, and they provided power for the hydraulic pumps. Fortunately the altitude peaked out low enough that there was enough aerodynamic pressure to keep the nose pointed in roughly the right direction.
He managed to get one APU running again, so he had power for the flight controls. But he still didn't have flight instruments. He knew he needed to pull to a fairly high angle of attack (AOA) to make a successful reentry, but if he pulled to too high an AOA the vehicle would lose directional stability. So he increased the AOA until he saw the nose start to slice off to the side, then decreased the AOA to regain control. He milked the AOA until he could see visually that his dive angle had decreased enough that he knew he had successfully reentered the atmosphere. Then he landed on one of the many dry lakes to the NW of Edwards.
All the above info is from At the Edge of Space, by Milt Thompson. Great book!
I certainly don't want to take away from Mike Melville's skill, as he is a very accomplished test pilot. He has had the opportunity to fly many oddball aircraft in his many years as a test pilot with Burt Rutan.
Yup, that would definitely be a boom for the air data system and angle of attack and sideslip probes. It is a very standard thing to see on flight test vehicles. You need to get that stuff well away from the rest of the aircraft so they are not affected by the flow field around the vehicle. After a bunch of flight testing you figure out how the flow field affects the accuracy of the production air data and angle of attack probes, which are mounted on the vehicle itself. So the production vehicle doesn't need the nose boom. But it is needed until they have enough data to calibrate the production probes.
Clear as mud?
But if I were doing a scientific or engineering paper, I would not use Excel.
Well, engineering is about actually getting some work done, not doing scientific papers. That is technical publishing, and I agree that Excel would be a poor choice there. But I concur that it is a great choice for quick and dirty calculations.
Don't pay too much attention to that Google conversion from Mach to speed. It only works if the temperature is 15 deg C (i.e. sea level under the International Standard Atmosphere). The speed of sound varies with the square root of the temperature, and it is a lot colder up where the X-43 was flying than it is at sea level, so the speed of sound is slower.
Mach 7 at sea level is about 8575 km/h, but Mach 7 at 100,000 ft it is only about 7615 km/h ( assuming the mythical day with standard temperature at both altitudes).
See Variation of speed of sound with altitude
Mach is a measure of speed in relation to the speed of sound (Vs). (Vs) varies with Temperature (t), and is calculated as such:
Vs = 332 + 0.6 * t
(Where Vs is in Meters/Sec, and t is in ^C)
The above equation is a very crude linearization, that only gives close to the right answer. The speed of sound is actually proportional to the square root of the temperature.
a = SQRT(1.4*286.99*T)
(Where a = speed of sound in m/s, 286.9 is the gas constant for air and T is the temperature in degrees Kelvin)
There's no way they could provide coverage like this in an area with a lot of high-rises. The people on the far side of the building would have horrible reception.
Do you lose cell phone coverage when you walk around the other side of a high-rise? I sure don't. They've learned how many antennae they need to install to provide seamless coverage. Why do you think they haven't done the same thing with this wireless broadband?
Actually 3700 flight hours is fairly small for a plane of this age. Most commercial planes have a 20,000 operating hour overhaul schedule.
Apparently the F/A-18A was designed for a 6,000 hr life, assuming a particular load spectrum that the Navy specified. There was a fair bit of air combat manoeuvring (ACM) included in that load spectrum, but they also assumed quite a bit of straight and level, 1g flight while transiting to and from ACM training areas. The USN training areas are typically off-shore, so there is a fair bit of transit time in any given ACM training mission, so the percentage of time at high g is fairly low.
Canada was shopping for multi-role fighters a couple of decades ago, and Canada was looking for an aircraft with an 8,000 hr life. The Canadian ACM training areas are very close to the fighter bases, so there is only a few minutes of transit time at each end of an ACM mission, which means a higher percentage of the time is spent at high g. McDonnell Douglas said the F-18 would meet the Canadian life spec, and they won the contract.
Canada started finding major airframe cracks a few years after the jets went into service. Some of the jets that had seen a lot of ACM were found to be near the end of their useful life with only around 2,000 hrs on the airframe. Canada had to do some major airframe overhauls, replace some of the major fuselage bulkheads, and adding reinforcements.
If this jet spent a long time with the Blue Angels, it might be at the end of its useful life.
Many people somehow think that Polly Vacher's flight around the world is better planned and organized than Jon Johanson's trip.
She, like Jon Johanson, had made sure that fuel was available at all her planned stops, but she did not make sure that fuel was available at all possible diversion airfields (the list of planned legs on her web site shows that McMurdo was a planned fuel stop).
She, like Jon Johanson, ran into higher than expected winds over Antartica, and had to divert. She, like Jon Johanson, diverted to an airfield that did not have fuel for her (she went back to her destination, but she had already used all the fuel in her fuel cache).
http://www.worldwings.org/route.htm& ID=226 & ID=228
http://worldwings.mantaur.co.uk/diary.aspx?mode=D& ID=230
http://worldwings.mantaur.co.uk/diary.aspx?mode=D& ID=232
http://worldwings.mantaur.co.uk/diary.aspx?mode=D
http://worldwings.mantaur.co.uk/diary.aspx?mode=D
I'm pretty sure that f-15's can cruise at or slightly above mach2 and the russians had a mig that could cruise at mach 3...
You seem to have a different definition of cruise than most people. The F-15 (and any other aircraft except the Concorde and SR-71 and its ilk) would need to use afterburner to sustain Mach 2, so it would be burning a lot of fuel, and could only sustain this condition for a short period. I wouldn't call this cruising. Cruising implies that the condition can be sustained for a long period, which pretty much means without the use of afterburners.
The SR-71 and its kin are a special case. The J-58 engine has several large ducts that allow air to go from the 4th stage of the compressor to the front of the afterburner, bypassing the aft stages of the compressor, the combustion chamber and the turbine. The engine is sort of acting as a ram jet at the design cruise condition. The bypass ducts are needed because the compressor inlet temperature is extremely high at the design Mach number. The air temperature gets even higher as you compress it, and even higher once you burn the fuel in the combustion chamber. But the turbine can only tolerate air at a certain temperature, so that naturally causes a problem. A ram jet would work, but they only generate usable thrust once you are moving quite fast. So the J-58 operates as a conventional turbo-jet at low speed, and then the bypass valves are opened up at high speed, converting it to sort of a ram jet cycle.
Actually, the concorde cruised at Mach 2 without afterburners. The afterburners were used for take-off, the acceleration from subsonic to M1.70, and then they were not needed for speeds above M1.7. This is documented in quite a few books about Concorde.
They didn't call it supercruise though, as that is a marketing buzz word developed recently to help sell fighters. There is no maqic about supercruise - it is just a matter of having an efficient intake system that decelerates the air to subsonic speed going into the engine, and an efficient nozzle system to accelerte the exhaust to supersonic speed so you can get net positive thrust.
The largest gun ever used was constructed by Nazi Germany and had an effective range of less than 30 kilometers (and that's horizontal distance, it couldn't have got that far up).
Actually, the Germans had a gun in 1918 that had a range of about 130 km. "From March through August of 1918, three of the guns shot 351 shells at Paris from the woods of Crepy, killing 256 and wounding 620." See: http://www.astronautix.com/lvs/parisgun.htm.
The way I figure it, the guys making the large bids are lawyers hoping to get the seller's business when he is sued by Apple. The lawyer who buys the song will likely get a pretty good return on his investment.
"The X-15 reached space -- that has been confirmed over and over. A slightly better, more modern X-15 could reach LEO"
The X-15 reached space for a few minutes at a time in a ballistic parabola. It's a big leap from a sub-orbital lob to going into orbit.
Sure, a super X-15 derivative might be able to reach LEO, but getting back would be a trick. Titanium isn't going to cut it due to greatly increased energy to be dissipated.
Pete Knight reached a top speed of about 4520 mph in X-15 #2 and there was enough structural damage from the heat that it never flew again. Orbital velocity is about 17,500 mph, or about 15 times the kinetic energy as 4520 mph.