Wow. I did not know that. Tres cool in a stupid sorta way.
Needing a start cart that provides electricity, start air, or both were pretty standard 1960s tech for both USAF & civilian.
The T-37’s J-69s had electric starters powered by, you guessed it, an external electric cart which had a diesel engine to turn a generator.
The more common system was used on T-38s, F-4s, most of the Century series, KC-135s, B707, DC-8, etc. That was the external air cart to provide compressed air to turn an air turbine motor. I had assumed SRs used the same system since it was standard in their day. These are powered by an ICE or diesel turning a low pressure high volume compressor. Typically you also use an external electrical cart as well.
The air start carts we use at the airline today are diesel. Though they’re only needed when the aircraft’s internal air source is inop.
I figure you already know all this, but maybe somebody else will learn something new.
@Francis Vaughan: I read the SR pilot manual online once. The TEB system had a countdown timer to track light-offs and IIRC 20 lights were provided per engine. Which was obviously thought to be plenty for the pretty much worst case mission.
Since we’re on to start carts now, I’ll cite for its more-detailed information on them, as well as the sheer pleasure in naming the the thread, Why do airplanes have buttholes?.
I have to admit that the APU exhaust of the 737 always makes me think of some tropical fish I had as a kid. Butt-hole indeed. The only thing lacking is a tan/brown kinky/curly hose about 1 foot across and 50 feet long trailing out of it.
Other aircraft types don’t seem nearly so … organic. Even though the purpose is identical on almost all.
Most WWII aircraft, especially fighters, had a radio… and that was about it for electronics. No navigation systems to initialize and be told where it is (or lock on to satellites/beacons), no weapons systems to be told what weapons are on which hardpoints, no sensors to calibrate and align. All those things were not installed on WWII aircraft until the pilot(s)/crew were aboard…
2min warmup between starting and full power for the GE CT7-8 turboshaft engine (the commercial version of the T-700 engine that powers the Black Hawk and Apache (among others). 5min warmup between starting and full power for the GE CF6-50C2 turbofan engine on the KC-10.
Operation Chrome Dome has already been mentioned.
Based on what I saw on my Air Force deployments, UAVs take even longer to prep for launch than a manned aircraft.
Remember that Predators & Reapers are controlled from Ground Control Stations; they are not autonomous. Global Hawks are semi-autonomous*, but still need a pilot “in the loop” in the event of traffic conflicts, mission changes, etc. This requires a persistent, robust, and secure satellite connection dedicated to flight control, in addition to the connection for the intel feed.
Fun Fact: the Global Hawk GCS doesn’t have flight controls. It has a keyboard and monitor for the pilot, who enters text-based commands, similar to “climb to 35,000ft” or “turn left to 270* heading”.
There are certain aircraft in the US military that do that now - there is external electrical power and cooling provided in an alert facility, or the aircraft has enough APU power to provide internal electrical power and cooling, for all systems to be powered-on. These aircraft and their missions are a high-enough priority that the expense of the increased rate of component failure (due to constantly being powered-on) has been accepted as “the cost of doing business”.
As LSLGuy described, the start cycle is the most stressful operation for a gas turbine engine. Modern turbine engines rely on airflow to cool themselves, to the extent that the turbine blades (behind the combustion section, in the hottest part of the engine) are almost always hollow, with tiny holes drilled in the leading edge, to provide the blade with a protective shroud of air that is sourced from the compressor section. While the compressor is still spooling up during the start sequence, there’s barely enough airflow to keep the fire lit, much less enough for cooling air.
The multiple spools of gas turbine engines are not mechanically linked, and do not spin at the same speed. Airflow through the engine (specifically, airflow through the turbine section) drives each spool independently, at the speed necessary for each spool’s particular section of the engine. As an example, the Rolls-Royce RB211-series engine is a three-spool design. One spool drives the fan, which are the large blades you see in the inlet of the engine; the majority of fan air goes around the engine. The other two spools drive the two separate compressor sections.
You might be surprised at how quickly a CVN can turn and accelerate. Even the CVs could accelerate pretty well - I spent a week or so on Kitty Hawk in the mid-'90s, and was surprised by how quickly she could “turn & burn” when Flight Quarters was set.
And that’s assuming, of course, that the ship isn’t already turned into the wind. I would expect that, while on station, they keep themselves aimed that way as a matter of routine.
It never occurred to me till you mentioned it: carriers want to be helpful to its clientele, so if possible they are turned into the wind…how much do they fiddle around with bow pointing for that during the course of a day, in peacetime and “normal” mission package time in war?
And along those lines (heh), I always have this image of a stationary landing field in the middle of the ocean; but with higher velocity into the wind they might shave a few gallons off of jet takeoff fuel.
Nope. You want the carrier moving fast for takeoffs or for landings. The whole point is to reduce the speed difference between the airplane and the ship as much as possible. That makes catapult launches and landings less violent and less wear-and-tearful on both ship and plane.
The fact the ship is moving is immaterial from the flying airplane’s point of view. It’s flying relative to the atmosphere until / unless the wheels are on the deck.
IANA expert on this stuff. Braodly speaking they operate in cycles. e.g. perform take offs for 30 minutes. Drive around with no airplanes doing anything for 90 minutes. Do landings for 30 minutes. Repeat as necessary. All those numbers are anally extracted but give a flavor for the idea.
During takeoffs and landings they want to be pointed into the wind and going fairly fast. But the ship needs to stay within the same general area, for pretty big values of “general area”. So assuming, say winds from the north, the ship may have to turn back to south and drive awhile between launches and recoveries so they can turn north again and go fast without progressing too far away from their patrol area or bumping into that pesky land stuff.
ETA: see here for more: Modern United States Navy carrier air operations - Wikipedia, and specifically the “cyclic operations” section. No edit time left to update my thumbnail above to match.
To the OP’s question, depends on what you mean by a few seconds. When I was on duty in the Quick Response area we had scrambles where the Hornets were wheels up in less than two minutes; but that was with the pilot strapped in and the CSU running the electronics with everything ready to go but engines.
A cold scramble we typically had the pilot dressed, strapped in and out the hangar in well under 5.
When we got a tour of the B-1 (coolest airplane ever) during one of my EW courses, they showed us the scramble button that a groundcrew member could push and the electronics and apu spooled up so that the aircrew could get off the ground in much less time.
One of my girlfriend’s Dad was a Voodoo pilot who had the record for a while and got it airborne in under a minute, according to him.
CVNs are constantly hunting for the best winds down the deck, whether it’s straight down the deck for launches, or a few degrees offset for landings. Add in turns to stay in/close to a particular piece of ocean, and you can rapidly get to a point where the only time the boat’s not turning is when they’re actually launching and recovering.
Compared to other vessels of similar displacement, CVNs are extremely overpowered, in order to get the most windspeed down the deck for launches and recoveries. This gives the aircraft better stall margins on approaches and departures, and reduces airframe stress from catapult shots and arrested landings. It also leads to situations where the escort ships in a Carrier Strike Group are slower than the escorted ship…
The CVN is certainly highly maneuverable in and of itself.
The whole protective fleet surrounding it is more of a PITA to maneuver aggressively. They do lots of in-place turns but there are still, AIUI, a lot of opportunity’s for OOD’s on destroyers & such to shit their pants when two ships are now aiming for the same spot of ocean after the carrier orders “By the right oblique, Harch!!” or whatever the boatish equivalent is.