Can the military launch satellites from jet planes

Isnt one or more still missing off the pylon of a B52 parked at Barksdale AFB ?
My joke but well... I never did hear the upshot of that one.....must have been an accounting error....

originally posted by: Zaphod58
a reply to: chr0naut

Quite a bit actually. It gives you a much smaller launch vehicle since the aircraft is the first stage. Saves a lot of money on fuel, and rocket costs. But it limits how large a payload you can launch.

I don't think it's as much of an improvement as people imagine. To put a satellite into orbit, going "up" is the smallest partof the job---it's the going sideways bit which really takes most of the energy.

So you can launch on a jetliner which saves a bit since you have less dense atmosphere to go through, but still most of your energetic job is in front of you and not behind you.

Once you work out the requirements to have a certain amount of fuel & oxidizer mass at a certain point to be able to get up to your delta V, it's not such an amazing architecture any more. They did these calculations in the 40's and 50's when it was an obvious thing to try.

What does work is multi-staging. If your aircraft is your first stage, it's a pretty lousy one since its so slow. You would never architect a rocket to have its staging event at that delta v/altitude.

It would work for small stuff but not the big stuff.

a reply to: mbkennel

And most satellites are going smaller.

a reply to: Bigburgh Personally I think it is more practical. Look at what is going on with these cube satellites. They could launch a large quantity of these type of satellites with one shot. There will always be a market for large satellites. I think the upcoming market will be for miniature/ cube satellites.

a reply to: mbkennel

a reply to: mbkennel
Mb,

. So If you're trying to put up something the size of Apollo Mir or Skylab I absolutely see what you're saying. However there's a couple of factors I think you may not be really factoring in.
1. Fuel: Modern rockets are basically flying fuel air explosive devices. The liquid rocket fuel used generally requires massive expensive and very precise equipment just to cool it to liquid state.... Jet fuel is stored in subsurface tanks made mostly by guys who MIGHT have a GED! Fueling the rocket requires highly qualified and intelligent employees in SPACE SUITS... you can get a job fueling planes at the airport as long as you have that GED and can explain why you are no longer the guy who got busted wearing work boots a beer helmet a giant cloth diaper and a smile anymore... They prefer you wear coveralls over your diaper of course...
2. Turbines versus rockets: Turbine technology is now at a point where they get pretty reasonable efficiency from sea level to 50 thousand feet... Rocket engines not so much. Despite decades of 100 million to 5 billion dollar yearly research funding to develop rocket engines that throttle well and have a larger altitude bracket of maximum efficiency, the gains haven't been nearly as large as the turbine engine has made. Much of this stems from the bell nozzles that they use. These nozzles are really one of the only real ways to get any real efficiency out of rocket propulsion, but the very complex internal shape combined with the extreme beating they take has made adjustable bells a seriously difficult task. (now I know you probably want to say, but rogue what about aerospikes? In response I'll say yes what about aerospikes? As of the current moment my thinking is that aerospike technology has been sucked into the black projects realm. Will we see them again? Oh yes... But when I have no idea)
3. Stage 2&3 engineering: Technically this is an extension of factor 2 but I believe it deserves its own section. Now logic dictates that you must engineer every stage after the first stage to survive the conditions the previous stages do. Now rocket first stages .. To say that they are violent is an understatement! On top of that you've got to get as much of your speed and altitude out of them which puts you in the position of doing most of your delta v gathering at altitudes and attitudes that are the most energy intensive situations to do them in. Whereas when you loft your systems to 40-70 thousand feet first... You can optimize your systems for high altitude high speed operations. This means lighter systems that don't have to survive the violence of a zero zero sea level launch. (zero zero is a term borrowed from military ejection seat terminology referencing zero altitude zero horizontal speed)
. to conclude... Like any engineering challenge you pays your money and you makes your pick.

I say screw all the multiple stages. SSTO man!!!! SSTO. We don't have one of those of course.

Would be nice if the USA had some sort of SSTO Space Bouncer to watch our back.