Orbiter-Forum  

Go Back   Orbiter-Forum > Far Side of the Moon > Backyard Rocketry
Register Blogs Orbinauts List Social Groups FAQ Projects Mark Forums Read

Backyard Rocketry Model, Amatuer, Experimental, and High Power Rocketry. Vehicle and Motor/Engine Design, Physics and Math, Fabrication, Flights, Testing and Evaluation. Share your rocket projects here!

Reply
 
Thread Tools
Old 06-23-2013, 06:16 PM   #1
OrbitalConfusion
Orbinaut
Default Launching Rocket from Aircraft

Hello! So Im just going to post some thoughts in a really unorganized way... Perhaps this will stimulate some conversation and I will walk away from this learning something new.


Ok, after thinking, then reading about this method.. Why the heck are we not doing this? Without attempting to crunch numbers It seems that if you carry a rocket to FL400-FL500 you bypass the thickest part of the atmosphere. The amount of propellant I THINK would be a substantial savings not to mention a lighter, smaller rocket.

I assume building a plane to handle this would be something out of a science fiction movie... I mean, the wing-span needed to create enough lift... Then, designing Jet engines with enough thrust to take the whole she-bang up to an appreciable altitude.

Maybe using jet engines for the first part and as the plane gets to an altitude you could fire some SRB's or liquid propellant engines to take the plane even higher?

I cant really find a reason why this would not work. I mean, I know your not going to want to strap a SaturnV on it, but for a small crew vehicle with the ability to also have a seperate model like the Soyuz progress for basic ISS supplies.. Why not?

What do you guys think?
OrbitalConfusion is offline   Reply With Quote
Thanked by:
Old 06-23-2013, 06:29 PM   #2
Zatnikitelman
Addon Developer
 
Zatnikitelman's Avatar
Default

https://en.wikipedia.org/wiki/Pegasus_%28rocket%29

The real advantage of an air-launched system isn't so much to reduce fuel consumption, as to be able to launch into any orbit, at any time. At the launch altitude, it's above most of the weather, and you can have the carrier plane at any latitude you want to use the most efficient trajectory.
Zatnikitelman is offline   Reply With Quote
Thanked by:
Old 06-23-2013, 06:38 PM   #3
garyw
O-F Administrator
 
garyw's Avatar


Default

Quote:
Originally Posted by Zatnikitelman View Post
 The real advantage of an air-launched system isn't so much to reduce fuel consumption, as to be able to launch into any orbit, at any time. At the launch altitude, it's above most of the weather, and you can have the carrier plane at any latitude you want to use the most efficient trajectory.
But the drawbacks are many.

1. No ground infrastructure so you have to take everything you need on the plane.
2. If you have an issue you have no where to abort the rocket, once it's detached it's going somewhere - maybe straight down.
3. Aircraft have a weight limit. You aren't going to launch a mars mission from an aircraft.
4. Atmosphere is not an issue with rockets. Speed is. An aircraft gives you something like 0.04% of speed and a bit more in altitude. When you factor in the weight issues it's just not worth it.
garyw is offline   Reply With Quote
Thanked by:
Old 06-23-2013, 06:53 PM   #4
Zatnikitelman
Addon Developer
 
Zatnikitelman's Avatar
Default

I'd actually argue that #1 is actually an advantage. The carrier vehicle is only the launch pad, there is still a flight control, assembly hangar, communications unit, etc. somewhere. But with an air launch system, that infrastructure can be anywhere. It doesn't have to be built on a coast, all you need is a runway long enough for the carrier. Or just reasonably priced transportation from the factory to the airport with the long enough runway.

#2 isn't also much of a disadvantage. If you're out over the open ocean, it doesn't matter where an out of control vehicle is going. Launching near land, at best if it crashes, you'll have to pay for minimal property damages, and at worst, it could kill a lot of people. Of course, range safety systems are supposed to "take care" of this.

No argument with #3 or #4. For smaller payloads like what Pegasus carries, the air launch system seems to be well worth it, but for much larger payloads, the cost of the "mobile launchpad" begins to get extreme.
Zatnikitelman is offline   Reply With Quote
Thanked by:
Old 06-23-2013, 07:19 PM   #5
garyw
O-F Administrator
 
garyw's Avatar


Default

#1 is a disadvantage - you can't take lox or liquid hydrogen with you (so no topping off the tanks) therefore, the rocket has to be solid. Solids don't provide much in the way of refinement in terms of thrust.

#2 could be a disadvantage if you lose a rocket when a ground facility could have helped avoid the issue.
garyw is offline   Reply With Quote
Thanked by:
Old 06-23-2013, 07:44 PM   #6
Zatnikitelman
Addon Developer
 
Zatnikitelman's Avatar
Default

I'm not sure you couldn't have some kind of LOX system on board. LH2 would probably take up too much space limiting you to Kerosene, but the inside of Stargazer looks relatively empty:
http://www.parabolicarc.com/2012/10/...unch-aircraft/

However, I haven't been able to find out if it's been stripped because it needs to be as light as possible, or if all the other components were simply unneeded and stripping them does save money for fuel regardless. A small vehicle in the Pegasus payload class wouldn't need much in the way of LOX top-off capabilities, and you might could even have some kind of regenerator on board, again weight-depending. If you used a larger aircraft, I'm sure you could fit cryogenic equipment at least for LOX.
Zatnikitelman is offline   Reply With Quote
Thanked by:
Old 06-23-2013, 08:32 PM   #7
Enjo
Mostly harmless
 
Enjo's Avatar


Default

I'm theorizing that this setup could be used for a realistic direct ascent.
Enjo is offline   Reply With Quote
Old 06-24-2013, 12:23 AM   #8
Galactic Penguin SST
Geek Penguin in GTO
 
Galactic Penguin SST's Avatar

Default

Shameless plug: this is exactly what will happen this Thursday. Launch report will be up by tomorrow!
Galactic Penguin SST is offline   Reply With Quote
Thanked by:
Old 06-24-2013, 05:02 PM   #9
OrbitalConfusion
Orbinaut
Default

I was thinking more in the lines of getting crew to and from the ISS. Light loads, nothing "heavy"... Maybe a light load of food supplies or emergency type situations. No mars type scenarios.

On top the rocket you could have a winged aircraft/spaceship so if something happened the crew could detach from rocket and glide to a designated location.


I guess using SRB would not be as good an option as using liquid where you could start and stop as needed.

FL800, you have the ability to on the fly change direction I think it would provide a great launch platform.
OrbitalConfusion is offline   Reply With Quote
Old 06-24-2013, 05:15 PM   #10
Urwumpe
Certain Super User
 
Urwumpe's Avatar

Default

The X-15 had LOX replenishment during flight by the B-52, you can use LOX in an air-launched rocket, but you can't do so for infinite time. A 8-hour long transfer to the launch site with a fueled rocket would be pretty impossible, but you could still use a small stop with a unfueled rocket near the launch site.
Urwumpe is offline   Reply With Quote
Old 06-24-2013, 05:48 PM   #11
garyw
O-F Administrator
 
garyw's Avatar


Default

Quote:
Originally Posted by OrbitalConfusion View Post
 I was thinking more in the lines of getting crew to and from the ISS. Light loads, nothing "heavy"... Maybe a light load of food supplies or emergency type situations. No mars type scenarios.
ISS crews are anything but light. Three people + life support + supplies + power, etc.

Quote:
Originally Posted by OrbitalConfusion View Post
 On top the rocket you could have a winged aircraft/spaceship so if something happened the crew could detach from rocket and glide to a designated location.
which would be even more mass.

Quote:
Originally Posted by OrbitalConfusion View Post
 I guess using SRB would not be as good an option as using liquid where you could start and stop as needed.
SRB's are fine but they can't be throttled and the ride can be bumpy.

Quote:
Originally Posted by OrbitalConfusion View Post
 FL800, you have the ability to on the fly change direction I think it would provide a great launch platform.
Except that today, no aircraft (unassisted) can reach 80,000ft. The U2 does about 75,000ft and look at it's wingspan. It's payload carrying capability is pretty much zero.

And how is 'being able to change direction' any advantage?
garyw is offline   Reply With Quote
Thanked by:
Old 07-04-2013, 06:04 PM   #12
Unstung
Cassini 2017
 
Unstung's Avatar
Default

Quote:
Originally Posted by garyw View Post
 4. Atmosphere is not an issue with rockets. Speed is. An aircraft gives you something like 0.04% of speed and a bit more in altitude. When you factor in the weight issues it's just not worth it.
How does this disadvantage compare to suborbital spacecraft such as the X-15 and SpaceShipOne/Two? It would not be in Virgin Galactic's favor if launching from White Knight is more costly than launching from the ground.
Unstung is offline   Reply With Quote
Old 07-04-2013, 06:06 PM   #13
garyw
O-F Administrator
 
garyw's Avatar


Default

Quote:
Originally Posted by Unstung View Post
 How does this disadvantage compare to suborbital spacecraft such as the X-15 and SpaceShipOne/Two? It would not be in Virgin Galactic's favor if launching from White Knight is more costly than launching from the ground.
It doesn't Suborbital for Spaceship one is about 120KM so it gets a nice head start from the aircraft.
garyw is offline   Reply With Quote
Old 08-02-2014, 08:04 PM   #14
n0mad23
Addon Developer
 
n0mad23's Avatar
Default

I've found myself back on the forum investigating a few things recently, and while this topic is a bit dated now, I thought I'd offer my 2 cents anyway.

I built the Daedalus B-52 Catamaran aerial launch platform about 3 years ago specifically to test some of the things raised in this thread. In using my Icarus converted Boeing X-37B micro-shuttle for a payload I can safely say that there is a definite fuel savings for an LEO launch from an aerial platform.

The Catamaran releases the rocket at between 15.24 and 18.28 km at around 290 m/s. The rocket assembly drops a really long way and needs massive pitch correction due to my own inabilities to program things here the way they need to be done so it's rather a Buck-Rogers approach, but does work (and provides a thrilling experience as well).

Stage One of my platform uses recycled Castor 120 solid body rockets with Castor 4Bs as boosters. On a recent test comparing my aerial launch platform to launching the same from the ground was really telling.

To get to 14 km, (the lowest the rocket falls after being released from the catamaran platform) my first stage burns over 3/4 of its fuel! To put this into perspective, when the rocket platform drops from the airplane, it's got 3/4 more fuel in its first stage than it would have simply getting this high. The release at 290 m/s forward velocity, while not huge in the scheme of orbital velocities is pretty beneficial as well.

G forces for stage one begin at around 2Gs and end around 4. Stage 2 (another Castor 120) begins about 2.5 and ends around 7 Gs. Stage 3 is a Black Arrow inspired H202/kerosene inspired rocket that helps dampen the Gs created by those solid rockets. A tiny hybrid is built in to the cowling connecting the stages to the X-37 and prove to be more than sufficient for achieving orbit and any minor plane changes necessary.

If anyone wants to try this for themselves, both addons are still up at Orbit Hanger Mods.
n0mad23 is offline   Reply With Quote
Thanked by:
Old 08-03-2014, 02:16 PM   #15
Odahs
Orbinaut
Default

This is an area where scram jets always seem very promising, with a top theoretical speed in the region of 8,000 m/s a scram jet equipped launch aircraft could be very useful indeed.
Odahs is offline   Reply With Quote
Reply

  Orbiter-Forum > Far Side of the Moon > Backyard Rocketry


Thread Tools

Posting Rules
BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
Forum Jump


All times are GMT. The time now is 04:54 PM.

Quick Links Need Help?


About Us | Rules & Guidelines | TOS Policy | Privacy Policy

Orbiter-Forum is hosted at Orbithangar.com
Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright 2007 - 2017, Orbiter-Forum.com. All rights reserved.