Author Topic: Air launch 8 tons  (Read 18047 times)

Offline alexterrell

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Air launch 8 tons
« on: 03/23/2008 04:59 pm »

I found a thread on air launched SSTO, but nothing on plain old simple air launched TSTO.
 

I was wondering whether it would be possible to air launch 8 tons to ISS orbit?

- 8 tons, because that's a useful payload and the mass of Dragon.
- Air launched, because I think there are advantages in cost and safety - I believed t/space's speel.

As a baseline, I took the An-124 which can in theory carry 150 tons of cargo. This is the most of any plane with a rear loading capability, and they're only about $30 million. I'm not sure if it can air drop 150 tons, but I've assumed it can. If extra cargo mass, extra range, or maneuverability is required, then the engines could be replaced with Trent 800s. (The Soviets were meant to make good airframes and crap engines).

Swift Launch and the air launched Polyot http://www.sciteclibrary.ru/eng/catalog/pages/5322.html describe a means to launch the rocket. The Polyot concept was not using the larger Antonov, so assumed a launch mass of 100 tons and a 3.5 ton payload.

Swift launch paper says that air launch saves about 1,200 fps off 29,000 - 30,000 fps needed for a surface launch. So converting into understandable measurements, and assuming two stages, with Delta V evenly split, Specific impulses of 346 seconds and 353 seconds, and a structure & rocket mass of 5%, I get the following results:
 

 

                                                                                                                                                                                                                                                                                                                                                                             

fpsm/s
Surface Launch29500 8,991.60  
Air launch28300 8,625.84  

   

   
Stage 1  4,312.92 m/s
Launch mass     150.00 tons

   
Isp 346seconds
Exhaust V 3394.26m/s

   
Mass ratio        3.56  
Dry mass       42.10 tons
Fuel mass     107.90 tons

   
Structure/engine mass        7.50 tons
Launch mass       34.60 tons

   
Stage 2  4,312.92 m/s
Launch mass       34.60 tons

   
Isp 353seconds
Exhaust V 3462.93m/s

   
Mass ratio        3.47  
Dry mass        9.96 tons
Fuel mass       24.64 tons

   
Structure/engine mass        1.73 tons
Launch mass        8.23 tons

Are these figures realistic?

Any one know if air launch corporation are serious?

Is any one serious looking at this concept?

 

 

 


Offline Jim

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RE: Air launch 8 tons
« Reply #1 on: 03/23/2008 05:59 pm »
Quote
alexterrell - 23/3/2008  1:59 PM
As a baseline, I took the An-124 which can in theory carry 150 tons of cargo. This is the most of any plane with a rear loading capability, and they're only about $30 million. I'm not sure if it can air drop 150 tons, but I've assumed it can.

Bad assumption.  The aircraft can't let go of that much weight at once

Offline Jirka Dlouhy

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Re: Air launch 8 tons
« Reply #2 on: 03/23/2008 06:29 pm »
Do you rate with Antonov An-225 Mrija ?

Offline meiza

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Re: Air launch 8 tons
« Reply #3 on: 03/23/2008 06:50 pm »
You could ask people with more experience from aircraft what it would take to redesign the An-124 for various airlaunch drop masses.

Offline alexterrell

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RE: Air launch 8 tons
« Reply #4 on: 03/23/2008 07:24 pm »
Quote
Jim - 23/3/2008  1:59 PM

Quote
alexterrell - 23/3/2008  1:59 PM
As a baseline, I took the An-124 which can in theory carry 150 tons of cargo. This is the most of any plane with a rear loading capability, and they're only about $30 million. I'm not sure if it can air drop 150 tons, but I've assumed it can.

Bad assumption.  The aircraft can't let go of that much weight at once

I was thinking it might be best to make the rocket weigh zero with a parabolic manoeuvre. I doubt the An-124 can do that with a full load at 10,000m, but put 4 Trent 800s and it probably could.

The Air Launch proposal just mentions its pushed out at 20m/s.

Offline alexterrell

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Re: Air launch 8 tons
« Reply #5 on: 03/23/2008 07:28 pm »
Quote
Jirka Dlouhy - 23/3/2008  2:29 PM

Do you rate with Antonov An-226 Mrija ?

Unfortunately there's only one of them. I always thought this was a weakness of the Interim Hotol project.

If more payload mass isrequired, or air drop is not feasible, then I'd look at Scaled Composites building a Custom Very Large Aircraft.

Offline Eerie

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Re: Air launch 8 tons
« Reply #6 on: 03/23/2008 07:39 pm »
Trying to fit existing airplane to drop rockets is wrong. It must be a special airplane.

Supersonic, making 5 mach. Then we are talking...  :)

Offline alexterrell

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Re: Air launch 8 tons
« Reply #7 on: 03/23/2008 07:43 pm »
Quote
meiza - 23/3/2008  2:50 PM

You could ask people with more experience from aircraft what it would take to redesign the An-124 for various airlaunch drop masses.

Good idea ...

Swift launch (http://mae.ucdavis.edu/faculty/sarigul/aiaa2001-4619.pdf) shows a parachute load of 290,000 lbs and claim no aircraft mods are required.

Offline alexterrell

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Re: Air launch 8 tons
« Reply #8 on: 03/23/2008 07:49 pm »
Quote
Eerie - 23/3/2008  3:39 PM

Trying to fit existing airplane to drop rockets is wrong. It must be a special airplane.

Supersonic, making 5 mach. Then we are talking...  :)

Most of the proposals at the moment use low cost sub-sonic aircraft where the velocity gain is not relevant. t/space and others extol the virtues of air launch as it provides for much lower drag losses, better rocket performance and improved safety.

A supersonic launcher would be rather expensive to develop. Bristol Spaceplanes has a nice concept: http://www.bristolspaceplanes.com/projects/spacecab.shtml

They reckon this would cost $1 billion to develop. I'd like to see a breakdown of that as replacing the Orbiter with a throw away rocket might make more sense.

Offline Eerie

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Re: Air launch 8 tons
« Reply #9 on: 03/23/2008 08:30 pm »
alexterrell;

How about Skylon? I like that project. (But not $10B they want for development).

Offline meiza

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Re: Air launch 8 tons
« Reply #10 on: 03/23/2008 11:58 pm »
Why Mach 5, why not Mach 10?

Mach 5 aircraft etc are pipe dreams, rockets do better by then. Subsonic air launch has substantial altitude (higher ISP, less drag) and positioning (catch right orbit, avoid range issues) advantages. And can use existing or only slightly modified aircraft.

Offline nacnud

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Re: Air launch 8 tons
« Reply #11 on: 03/24/2008 12:00 am »
Quote
alexterrell - 23/3/2008  9:28 PM

Quote
Jirka Dlouhy - 23/3/2008  2:29 PM

Do you rate with Antonov An-226 Mrija ?

Unfortunately there's only one of them. I always thought this was a weakness of the Interim Hotol project.

There is another, it's just in bits. Are you any good at jigsaws?

Offline daveglo

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Re: Air launch 8 tons
« Reply #12 on: 03/24/2008 12:48 am »
If you want to see a video of the concept in action (albeit smaller launch weight), try this:

http://www.airlaunchllc.com/

Offline Lampyridae

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Re: Air launch 8 tons
« Reply #13 on: 03/24/2008 02:58 am »
Quote
meiza - 24/3/2008  10:58 AM

Why Mach 5, why not Mach 10?

Mach 5 aircraft etc are pipe dreams, rockets do better by then. Subsonic air launch has substantial altitude (higher ISP, less drag) and positioning (catch right orbit, avoid range issues) advantages. And can use existing or only slightly modified aircraft.

A hybrid rocket / airbreathing first stage would be the best bet in this regime. Supersonic separation, scramjets etc. are all avoided by separating out of the atmosphere. A modified Centaur could place maybe 8 tonnes in orbit with this method. Although it's not really air launch anymore, except that the airframe carries it up partway.

Offline HMXHMX

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RE: Air launch 8 tons
« Reply #14 on: 03/24/2008 03:16 am »
A few insights from AirLaunch LLC:

Yes, we are serious...

The An225 can't deploy anything (unless it is done "Enterprise" style).  It has no aft cargo door.  The An124 can probably deploy 100-150 tons but would need modifications, since the ramp couldn't take the loads.  We deployed 72K lbs. from the C-17 without any zero-g maneuver or any impact on the aircraft whatever; pilots reported the drop as very smooth, a non-event...

For t/Space we did look at a 747-200 modification and a belly drop.  We could deploy at least 100 tons that way, and flying the simulator (full motion) was uneventful.  Pretty much any pilot could handle it.

If you want to go above a launch mass of 100 tons, then you need a new custom aircraft.  That was the original t/Space plan, until the NASA CE&R contracts were swept aside by the incoming new administrator in favor of a pre-ordained solution.  I leave the design of such an aircraft as an exercise for the reader...



Offline alexterrell

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RE: Air launch 8 tons
« Reply #15 on: 03/24/2008 09:01 am »
Quote
HMXHMX - 23/3/2008  11:16 PM

A few insights from AirLaunch LLC:

Yes, we are serious...

The An225 can't deploy anything (unless it is done "Enterprise" style).  It has no aft cargo door.  The An124 can probably deploy 100-150 tons but would need modifications, since the ramp couldn't take the loads.  We deployed 72K lbs. from the C-17 without any zero-g maneuver or any impact on the aircraft whatever; pilots reported the drop as very smooth, a non-event...

For t/Space we did look at a 747-200 modification and a belly drop.  We could deploy at least 100 tons that way, and flying the simulator (full motion) was uneventful.  Pretty much any pilot could handle it.

If you want to go above a launch mass of 100 tons, then you need a new custom aircraft.  That was the original t/Space plan, until the NASA CE&R contracts were swept aside by the incoming new administrator in favor of a pre-ordained solution.  I leave the design of such an aircraft as an exercise for the reader...



Thanks for the insight. There are three sub sonic air launch concepts I've come across.

I know Air Launch LLC are serious with Quickreach 1, and I'd love to see Quickreach II get developed. However, without the new Corona capsule, I was wondering if it could be sized for Dragon.

The serious question was about the Russian Air Launch Aerospace Corp (An 124 + Polyot).

Then finally there's the Swift Launch proposal. I think this one is unfunded though.

By the way, Astronautix has a great line on t/space:
"t/Space's partners demonstrated the technology that would ensure that it could deliver a launch system that would deliver a crew of four to orbit at a cost of $20 million per launch within three years of go-ahead. This was less than 10% the cost and half the time that NASA planned to spend on its own CEV approach. Naturally this was of no interest to NASA and further contracts were not forthcoming."

Offline Eerie

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Re: Air launch 8 tons
« Reply #16 on: 03/24/2008 09:08 am »
Quote
meiza - 23/3/2008  7:58 PM

Why Mach 5, why not Mach 10?

Mach 5 aircraft etc are pipe dreams, rockets do better by then. Subsonic air launch has substantial altitude (higher ISP, less drag) and positioning (catch right orbit, avoid range issues) advantages. And can use existing or only slightly modified aircraft.

Come on, everything is a pipe dream until it gets built.

Offline cb6785

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RE: Air launch 8 tons
« Reply #17 on: 03/24/2008 10:47 am »
Quote
I was thinking it might be best to make the rocket weigh zero with a parabolic manoeuvre. I doubt the An-124 can do that with a full load at 10,000m, but put 4 Trent 800s and it probably could.

I don't think you really want to do it this way. First of all even on one "empty" zero-g flight the airplane experiences physical stress comparabel to 8 normal flights. You can imagine what happens if you do that on a regular basis with 150tons at your belly.
You get around 1,8 g for each 20 sek prior and after to the zero-g phase. The first one could bring you serious structural problems due to the extra mass, but even if it works...I don't want to have to get a plane with additional 150tons through the first one, then having the payload removed while in zero-g and then going through another critical 1,8g phase in a totally different mass configuration.....
You know, if I’d had a seat you wouldn’t still see me in this thing. - Chuck Yeager

Offline meiza

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Re: Air launch 8 tons
« Reply #18 on: 03/24/2008 01:34 pm »
Quote
Eerie - 24/3/2008  11:08 AM

Quote
meiza - 23/3/2008  7:58 PM

Why Mach 5, why not Mach 10?

Mach 5 aircraft etc are pipe dreams, rockets do better by then. Subsonic air launch has substantial altitude (higher ISP, less drag) and positioning (catch right orbit, avoid range issues) advantages. And can use existing or only slightly modified aircraft.

Come on, everything is a pipe dream until it gets built.

Then why not hope for monatomic hydrogen? SSTO to Mars and back.

A Mach 5 aircraft just for rocket launch doesn't pass the cost benefit ratio analysis.

Offline Big Al

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Re: Air launch 8 tons
« Reply #19 on: 03/24/2008 02:18 pm »
The whole idea behind air launch is to achieve flexibility in launching a spacecraft. Does air launch really save you money? This is a good question for Orbital, how do Pegasus costs compare to a ground launch for the same satellite?
 Rather than an air launch, you would be better off with a rocket sled accelerating to maybe Mach 3 and then a winged vehicle and finally a third stage to place the pay load in orbit. The winged rocket and the sled are reusable, should cut costs. The sled would be rocket powered, I don’t think a magnetic powered sled would ever pay for it’s self.

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