Titanium Downpipe???
01-13-05, 07:33 PM
#28
Originally Posted by RedR1
Dude, you suck!! I was just about to type about the takeoff with only 150-200 lbs of fuel, then the refueling due to gaps in the fuselage. . . . you beat me to the punch!! but the exterior skin was not made of 100% titanium, it was a composite of like 12 other metals and what not. I forget the exact metals.
150-200 lbs of fuel wouldn't even get you out of the hangar after engine start.
You have tankers speadout across the flight path. Not 4 minutes away (they would be over the base?) Yes, you do refuel after takeoff, but as you read along you'll see it's not that close or rushed
The skin, stringers, frames & landing gear are constructed from 3-2.5 & 6-4 Ti. Over 90% of the airframe
The inlet "spikes" , nose & chine panels , along with the "pie" panels along the wing leading & trailing edges, are constructed from a asbestos laminate material.
The engines & exhaust use other higher temp metals ( hastelloy & Rene 41).
The plane has a max fuel cap of 80K lbs (SR-71). It normally is dispatched with a fuel load of 55-65K lbs. Why? In the event of a air turnback it wouldn't have dump so much fuel to meet max landing weight restrictions.
Plus, the fuel tanks are inert with N2. They are +2 to 3 psi above ambient pressure ( N2 is serviced 3-4 hrs prior to flight). The gaps between the skin are very tight & internally sealed. Lockheed struggled with the fuel tank sealant issues (temp extremes, elasticity & ability to adhere to Ti) & never did completely solve it.
The plane is not cleared for high speed flight until it purges all the ambient air by air refueling to max capacity. Then, as the fuel is burned off, the void is replaced with N2.
In rare instances we would duplicate this maneuver on the ground by servicing the N2 (actually LN2) & completely filling the fuel tanks (13). Then we would defuel the plane to 55-65K lbs. (this action purges the tanks of all the air). The plane would go to speed & altitude after takeoff (approximately 40-50 minutes of flight, 1,500 -2000 miles away). before hitting a tanker.
