Fastest Windshield on Earth

17 responses to “Fastest Windshield on Earth”

1. 

   jurvetson

   Sep 10, 2010 at 6:26 am

   Final configuration, with the left-side window above:
   

   Earlier design…. a larger polygon… Yikes!
   
   

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2. 

   Victor1

   Sep 10, 2010 at 8:32 am

   I think the wording used then was "to the edge of space…" describing the X-15. Interestingly enough, the SR-71 flys nearly as fast and took off on its own.

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3. 

   Dr DAD (Daniel A D’Auria MD)

   Sep 10, 2010 at 9:43 am

   An interesting piece of aviation history. Intriguing that the ventral fin had to be jettisoned before landing as the landing gear did not extend beyond it.

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4. 

   Astrocatou

   Sep 10, 2010 at 10:05 am

   [http://www.flickr.com/photos/victor1/]
   A lot can happen in ?? 10 years !!
   Esp in the Cold war…
   That Kraft sig is a beauty…
   Did he not sit it out as the Cap Com for years due to a heart glitch ?

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5. 

   jurvetson

   Sep 10, 2010 at 3:29 pm

   Victor: nearly as fast? The SR-71 record is 2,193 MPH. The X-15 would have passing speed of 2,300 MPH more than that. Whoom!

   That would rattle ’em as the SR-71 pilots are used to out-running surface-to-air missiles by just accelerating away. (A fellow Estonian Air Force pilot emailed that the Blackbird successfully outran nearly 4000 missiles).

   Meanwhile, here’s Pete with the fastest aircraft ever:

   

   And the contrail of the XLR-99 rocket engine (click photo for more info):

   

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6. 

   Astrocatou

   Sep 10, 2010 at 4:56 pm

   Hmmm…
   So much for my advanced tech theory…
   380,000 ft….!!

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7. 

   jhagerty52

   Sep 10, 2010 at 6:24 pm

   Dave: The SR-71 has a top speed of Mach 3.62 at full power plus 60% afterburner. So why can’t it go faster with 100% AB? Because at that speed the shock wave from the nose has spread out to the engine intakes and they’d start injesting "dirty air". Max cruise altitude was under 100K ft. I could go higher on a powered climb and coast through an apogee over 100K, but not be able to sustain it.

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8. 

   Astrocatou

   Sep 10, 2010 at 6:58 pm

   [http://www.flickr.com/photos/31160766@N02]
   thanks for that !
   Hell of a ride in any event !

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9. 

   jhagerty52

   Sep 11, 2010 at 5:52 am

   I just realized in that shot of Pete Knight, the cockpit with the oval windows makes it look like the Nautilus from Disney’s 20K Leagues!

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10. 

    nhr

    Sep 11, 2010 at 3:57 pm

    The space shuttle’s flight pattern is actually quite similar to the X-15’s — i.e. an initial rocket-powered acceleration, a coasting regime during which the flight path’s maximum altitude is reached, followed by an unpowered glide towards landing.
    In that sense, the space shuttle’s micrometeroid-resistant fused quartz windows could be considered to be the fastest windows ever flown — the shuttle’s reentry velocity being about Mach 25.

    It seems the X-15’s windows were made of soda-lime or alumino-silicate glass instead of fused quartz. Note also that the X-15’s Inconel window frames seem to have been prone to heat-induced buckling and had to be replaced with titanium ones.

    The X-15’s cracked canopy glass is evocative of a tempered "safety" glass’ failure pattern — i.e. the residual stresses left in the glass after manufacturing ensuring that the glass breaks up in little pieces, instead of large shards.

    I wonder if — just like normal, non optically-annealed tempered glass — your X-15’s window would exhibit optical stress patterns when observed under a polariscope.
    You could check for these stresses by shining a polarized light source — a computer or television LCD would do nicely — through the X-15’s window and observing it using a polarizing filter.

    The optical effect of the residual stresses in the tempered glass used in this diving mask, for example, are quite evident when observed using polarized light and a polarizing filter. The bright background LCD screen appears dark in the picture due to the camera-mounted filter’s polarizing axis being rotated 90º relative to the LCD’s.

    

    Of course, I decline any responsibility about the marital consequences of you mounting an X-15’s window in front of your LCD TV to scrutinize it, thereby confirming your wife’s legitimate suspicion that there’s something not quite normal about you 😉

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11. 

    jurvetson

    Sep 11, 2010 at 7:54 pm

    heh, that’s why I said fastest on Earth…. 😉

    The Apollo ones went faster still (speed table). So do I have quartz here:

    

    Cool idea on the optical stress test. Could I just use reflected sunlight off a glass table as my polarized light source:

    

    but I’d use the polarizing filter from the Canon instead of curved glasses…

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12. 

    nhr

    Sep 12, 2010 at 10:03 am

    > The Apollo ones went faster still (speed table). So do I have quartz here:

    I have no idea how one could reliably test at home whether a window’s material is fused quartz.

    The problem with spaceship quartz windows is that there’s a high probability that the material contains additives, or has had a coating applied to it to block exoatmospheric radiations — including UV — that might be harmful to the crew.

    On the off chance that such a UV-blocking treatment has not been applied to the window panes you have, one could distinguish glass and quartz as follows:

    Quartz is quite different from soda-lime or alumino-silicate glass in that it tends to transmit UV light quite well. At a wavelength of 250nm, glass, unlike quartz, is essentially opaque.

    The trick is thus to use a UV-sensitive digital camera and compare the pictures taken with, and without, the spaceship window in front of the camera.

    Note that mythical, rare and expensive UV-capable photographic lenses are not required for such a simple test. A 250nm shortpass filter and a pinhole mounted on a UV-sensitive camera should be entirely sufficient.

    An untreated, pure quartz spaceship window would be essentially transparent and have little effect on pinhole UV photography.

    OTOH, a quartz window with a radiation-blocking treatment, or a glass window would presumably appear opaque when photographed using 250nm UV light.
    In such a case, determining the material difference between quartz and glass would require e.g. a mass spectrometer. Collecting the required amount of analytic sample material from extremely hard objects like quartz or alumino-silicate glass could be done e.g. by using as a scraping tool the conveniently chiseled and mounted bits of sapphire or diamond often found in the vicinity of people of the female gender 😉

    In a similar vein, determining at home whether a window retainer frame is made of Inconel or of titanium is quite difficult.
    Some Inconel alloy variants are magnetic, whilst titanium alloys are almost never magnetic. Thus, if your X-15 window frame happens to attract magnets, one can be fairly sure it’s made of Inconel.
    OTOH, if magnets are not attracted, again, a delicate scraping of that hard material and mass spectrometry might be required to determine its exact nature.
    Are you going to sue the vendor if the X-15 window retainer frame is made of titanium instead of the advertised Inconel ? 😉

    > Could I just use reflected sunlight off a glass table as my polarized light source:

    A glass table might be suboptimal, as it could superimpose its own optical stress patterns on the analysis light.
    The sunlight rays reflect off the glass table at two interfaces:

    1) the tabletop air-glass interface
    2) the glass-air interface at the lower side of the glass pane

    The light reflected by interface 2 has a lower, but still fairly similar intensity to the one reflected by interface 1.
    One can indeed see that the double images of your eyewear frame’s upper and lower parts, caused by reflections on interface 1 and 2, are quite similar in "brightness" or intensity.

    The problem is that the reflection from interface 2 travels through the glass table’s material, and its polarization will thus be affected by the optical stresses present in the glass table.

    A laptop computer’s LCD panel displaying a white window, or an iPad, or a LCD TV are thus likely to be a much more uniform source of polarized light than a glass table…

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13. 

    jurvetson

    Sep 14, 2010 at 5:51 am

    Alas, it is not magnetic, but these studies hint at some other tests one could perform… =)

    

    The temp regime for the X-15 is pretty brutal…. They relied on the superalloy to turn the outer shell into a giant heat sink (both graphs from the NASA X-15 eBook)

    

    P.S. Inscription on the back of the frame:

    

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14. 

    Astrocatou

    Sep 17, 2010 at 3:49 pm

    I looked at the auction sites you linked some time ago…
    (and thanks for that)

    No Apollo gear in my office yet !

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15. 

    m.p.moody

    Jul 16, 2011 at 1:04 am

    Looking at a video of the damage to the X-15 #2 after it’s record breaking flight, it’s a miracle it landed safely http://www.youtube.com/watch?v=wHuBsBOF4R8

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16. 

    jurvetson

    Mar 14, 2012 at 6:01 pm

    That’s a great video. It just gets baked! (and for the latest Mach 20 scramjet, the airfoil surfaces have to be ablative).

    Astronaut Ed Lu visited recently to tour the artifacts, and he helped explain why I have this window, i.e., why is it detached from the rest of the vehicle? The window canopy is single use, and is replaced after the flight. Of course!

    And it reminded him of an interest historical footnote to the SR-71 Blackbird. The U.S. was quite concerned that the MIG-25 Foxbat could catch and outrun the SR-71. When this happened, the U.S. engineers were perplexed at how the Russians possibly could do that. Well, they ran their engines at 180% of rated power and destroyed them in the process. They were single-use engines, replaced after each flight!

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17. 

    taggywu

    Jun 24, 2013 at 11:46 am

    Steve, I had the opportunity to fly the Foxbat (also L-39 Albatross and MiG-21 Fishbed) at Zhukovsky Airbase in Russia in 1993. The Foxbat is a ridiculously over designed, heavy crude jet. Can’t hold a candle to Blackbird, but nonetheless a pretty sweet ride for a civilian going mach 2.85 and 68,500 feet. The taxiways, runways and all possible parking areas were littered with cannibalized jets – makes sense that the engines on the Foxbat were considered "disposable".

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