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Space Forum / Shuttle / August 2007Here she comes
Looking good! > Looking good! Appearently a very smooth TD. I'll be interested in the after-action pictures of the gouge (I'm sure the CFD people will be, too). I was on I-405 at the time (actually, since this is SoCal, I was on "the 405" ;-} ), I had to settle for 90s or less of audio. Once again, I go to wondering what the background noise is that we hear during landings. The mike seems to be near some equipment, and the gain turned way up -- I'm not sure what we're listening for that we would need to do that. /dps >> Looking good! > [quoted text clipped - 7 lines] > way up -- I'm not sure what we're listening for that we would need to do > that. Do you mean the whining noise that sort of goes up and down? Isn't that the APU? Just before touchdown there was also a rapid series of loud noises that sounded like a photographic camera taking pictures at high speed. On film. It sounded like the winder on my 35mm SLR, but faster ;) >>> Looking good! >> [quoted text clipped - 14 lines] >sounded like a photographic camera taking pictures at high speed. On >film. It sounded like the winder on my 35mm SLR, but faster ;) There are the Chase planes (2 T38's IIRC). And the steady frequency bap bap bap are the APU's. I did hear an auto shutter camera too. Jim in Houston. Contrary to popular opinion RN does not mean Real Nerd! Teddy Roosevelt's mother said: "Fill what is empty, empty what is full, and scratch where it itches"  SignaturePosted via a free Usenet account from http://www.teranews.com On Aug 21, 1:16 pm, Jim in Houston <nospamjamesgoo...@sbcglobal.netnospam> wrote: > >>> Looking good! > [quoted text clipped - 27 lines] > > - Show quoted text - Jim, Yeah . . the camera was obvious. I envy the lucky snot able to be there and shoot pictures. *S* John >Jim, > >Yeah . . the camera was obvious. I envy the lucky snot able to be >there and shoot pictures. *S* > >John You betcha. I gotta make it down there someday to see that. Was it me or were the sonic booms allot louder? Jim in Houston. Contrary to popular opinion RN does not mean Real Nerd! Teddy Roosevelt's mother said: "Fill what is empty, empty what is full, and scratch where it itches" SignaturePosted via a free Usenet account from http://www.teranews.com > >> Looking good! > [quoted text clipped - 14 lines] > sounded like a photographic camera taking pictures at high speed. On > film. It sounded like the winder on my 35mm SLR, but faster ;) I think it is in fact, the APUs. I have heard it during several landings and wondered what it was. It seemed louder today, probably because of wind condtions. I wondered what in the world it was that made that "chuffing" sound (kinda like a Baldwin 4-8-2 'Mountain Type' locomotive). The answer came less than a minute later when the view of the stopped orbiter switched from visible light to IR. In time with the noise, you could see bright white exhaust puffs from the base of the vehicle's vertical tail, very near the location of the APUs. I was kinda surprised that the APUs seemed to puff rather than emit a continous exhaust like an aircraft APU, especially since I thought the APU was a turbine unit that burned Hydrazine. To any of you professional or amateur (active or retired) FDO's: What impact, if any, does this have on the vehicle after MECO prior to APU shutdown or during orbital flight after APU start up in preparation for entry? I would imagine whatever propulsive effects there are during powered ascent would disappear as mere statisical noise so far as controlling the vehicle is concerned. Take care . . . John >> >> Looking good! >> [quoted text clipped - 35 lines] > ascent would disappear as mere statisical noise so far as controlling > the vehicle is concerned. The APUs use an on-off control system. When the RPM of an APU drops below the threshold, the Hydrazine is turned on. When it gets above some other RPM the Hydrazine is turned off. The APU turbine is coasting, turning angular momentum into hydraulic pressure. The Chuffing sound is when the APU is coming on briefly, followed by a long coast because none of the control surfaces are moving on the ground. |
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