Scramjet SSTO

On 6/20/2010 6:19 PM, Alain Fournier wrote:
Pat Flannery wrote:

I think that the AF minishuttle was a classified project. If so, those
that have first hand information about the project wouldn't be talking.

It was, but decades and the Freedom Of Information Act changed that all;
here's a four-part history of the whole thing from "The Space Review":
http://www.thespacereview.com/article/1569/1
http://www.thespacereview.com/article/1580/1
http://www.thespacereview.com/article/1591/1
http://www.thespacereview.com/article/1608/1
You know what killed it when all was said and done?
The price of the expendable drop tank.

Pat

In article ,
says...

"Alain Fournier" wrote in message
...
Jeff Findley wrote:
The purpose of an aerospike is to optimize the expansion ratio
(performance) from sea level to vacuum. Adding air launch to such a
vehicle seems counter intuitive.

Indeed.


I'm not so sure about that. What doesn't make sense is lifting all that
oxidizer from the ground to 50k feet, a jet engine has ten to fifteen times
the isp than a rocket in the lower atmosphere since it isn't carrying
oxidizer. It doesn't make sense to use a liquid rocket, even
an aerospike until at higher altitudes.

It can reduce overall costs. The costs of a huge carrier aircraft can't
be ignored. Also, separation in the atmosphere can be... tricky. If
you research the history of ordinance separation you'll find quite a few
accidents. Staging *out* of the atmosphere is generally easier than
doing it in the atmosphere. Aerodynamics are a real p.i.t.a. when
you're talking about two vehicles flying *that* close to each other.

Scaled Composites seems to do pretty well with their small suborbital
essentially using a jet powered reusable first stage.

Scaled Composites is defiantly a risk taking company, but they also do
*a lot* of their own work in house, which reduces cost. Also, they're
doing suborbital vehicles, so the size of the carrier aircraft can be
rather small when compared to what you'd need for an orbital vehicle.

As I've mentioned in another posting, take a look at past proposals for
air launched reusable orbital vehicles and you'll see that even when
they were using the biggest carrier aircraft available at the time (e.g.
B-747 or C-5), the actual orbital vehicle (payload) ended up being
rather tiny.

Basing an orbital launch vehicle of a reasonable size (e.g. Falcon 9) on
an air launch architecture will require you to build an aircraft much
bigger than any built to date. There will be *huge* costs associated
with a carrier vehicle this big.

Falcon 9 has a fueled mass of 325 metric tons and a LEO payload of about
10,000 kg, and it's a tad undersized when compared to Atlas V or Delta
IV.

Riddle me this: How many aircraft can carry a payload of 300+ metric
tons? Certainly not a C-5. It's payload is only about 125 metric tons.
Even the huge An-225 (so expensive only one was ever completed and
flown) can only carry 250 metric tons, so you're talking about needing a
carrier aircraft bigger than the heaviest cargo lifter ever built.

Even if it were possible to acquire such an aircraft, you don't let an
asset like that sit in a hangar. It costs far to much to do so. That
thing had better be launching several times a week.

Jeff
--
The only decision you'll have to make is
Who goes in after the snake in the morning?

In article
tatelephone,
says...

On 6/20/2010 6:19 PM, Alain Fournier wrote:
Pat Flannery wrote:

I think that the AF minishuttle was a classified project. If so, those
that have first hand information about the project wouldn't be talking.

It was, but decades and the Freedom Of Information Act changed that all;
here's a four-part history of the whole thing from "The Space Review":
http://www.thespacereview.com/article/1569/1
http://www.thespacereview.com/article/1580/1
http://www.thespacereview.com/article/1591/1
http://www.thespacereview.com/article/1608/1
You know what killed it when all was said and done?
The price of the expendable drop tank.

Anything burning fluorine as an oxidizer isn't going to be cheap. This
just goes to show that performance was such a problem that they were
willing to accept the cost and hazards associated with handling and
flying on fluorine.

Jeff
--
The only decision you'll have to make is
Who goes in after the snake in the morning?

Jeff Findley wrote:

Two additional comments within:


In article ,

Scaled Composites is defiantly a risk taking company, but they also do
*a lot* of their own work in house, which reduces cost. Also, they're
doing suborbital vehicles, so the size of the carrier aircraft can be
rather small when compared to what you'd need for an orbital vehicle.


And note, the various hand-waving proposals to use White Knight Two as an
orbital launch platform are showing numbers of only around 200kg to LEO.
That's pretty small.

As Jeff says, it's not impossible, but it's not necessarily a great solution
either.

Riddle me this: How many aircraft can carry a payload of 300+ metric
tons? Certainly not a C-5. It's payload is only about 125 metric
tons. Even the huge An-225 (so expensive only one was ever completed
and flown) can only carry 250 metric tons, so you're talking about
needing a carrier aircraft bigger than the heaviest cargo lifter ever
built.

They did start work on completing the 2nd airframe, but apparently that has
been abandoned. It's shame.



Even if it were possible to acquire such an aircraft, you don't let an
asset like that sit in a hangar. It costs far to much to do so. That
thing had better be launching several times a week.

Jeff

--
Greg Moore
Ask me about lily, an RPI based CMC.

Jeff Findley wrote:

Anything burning fluorine as an oxidizer isn't going to be cheap.

Any time the answer involves fluorine, one has to wonder if you're asking
the right question. :-)


This just goes to show that performance was such a problem that they
were willing to accept the cost and hazards associated with handling
and flying on fluorine.

Jeff

--
Greg Moore
Ask me about lily, an RPI based CMC.

In article ,
says...

Jeff Findley wrote:
Riddle me this: How many aircraft can carry a payload of 300+ metric
tons? Certainly not a C-5. It's payload is only about 125 metric
tons. Even the huge An-225 (so expensive only one was ever completed
and flown) can only carry 250 metric tons, so you're talking about
needing a carrier aircraft bigger than the heaviest cargo lifter ever
built.

They did start work on completing the 2nd airframe, but apparently that has
been abandoned. It's shame.

It is a shame. My brother is a Civil Engineer in the power generation
industry and got to see the An-225 in person. They were unloading a
huge part of a power plant (turbine?) at an airport near a power plant
he was working on. He took some awesome pictures of the unloading
process.

Jeff
--
The only decision you'll have to make is
Who goes in after the snake in the morning?

Jeff Findley wrote:
In article ,
says...

Jeff Findley wrote:
Riddle me this: How many aircraft can carry a payload of 300+ metric
tons? Certainly not a C-5. It's payload is only about 125 metric
tons. Even the huge An-225 (so expensive only one was ever completed
and flown) can only carry 250 metric tons, so you're talking about
needing a carrier aircraft bigger than the heaviest cargo lifter
ever built.

They did start work on completing the 2nd airframe, but apparently
that has been abandoned. It's shame.

It is a shame. My brother is a Civil Engineer in the power generation
industry and got to see the An-225 in person. They were unloading a
huge part of a power plant (turbine?) at an airport near a power plant
he was working on. He took some awesome pictures of the unloading
process.


Yeah, it's an impressive plane. Wonder how long before it's equalled or
surpassed (as I'm sure it will be eventually.


Jeff

--
Greg Moore
Ask me about lily, an RPI based CMC.

"Greg D. Moore \(Strider\)" wrote:
Yeah, it's an impressive plane. Wonder how long before it's
equalled or surpassed (as I'm sure it will be eventually.

Perhaps not until a blended-wing-body transport is developed?

rick jones
--
the road to hell is paved with business decisions...
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

On 6/21/2010 8:50 AM, Greg D. Moore (Strider) wrote:

Anything burning fluorine as an oxidizer isn't going to be cheap.

Any time the answer involves fluorine, one has to wonder if you're asking
the right question. :-)

One of the few things I would think was worse to get on my skin than RFNA.*
I think fluorine was what the Alien in the movies was using for blood,
considering what it was shown to do anything it got on the films.
The logistics of tanking it up with that would have been a nightmare;
not to mention what the plumbing, turbopumps, and propellant tanks would
have to be made of.
Even the exhaust on the AMPS-1 engine for the FDL-5 looked nasty:
http://www.picturetrail.com/sfx/albu...9229/245214005
I think that's what Martian War Machine heat rays are powered by. :-D

* I've seen that stuff in real life, and it is spooky as hell.

Pat

On 6/21/2010 3:00 PM, Jeff Findley wrote:

It is a shame. My brother is a Civil Engineer in the power generation
industry and got to see the An-225 in person. They were unloading a
huge part of a power plant (turbine?) at an airport near a power plant
he was working on. He took some awesome pictures of the unloading
process.

Ruslan is a most useful aircraft (one on a cargo mission actually landed
at Fargo several years back and enveloped nearby traffic in a
jet-engine-induced dust storm as it cranked up its engines for takeoff),
but Mriya is too specialized; it was designed to carry oversized
payloads on its back rather than internally, and that really creates
high drag and poor fuel economy due to that drag; now something like
Mriya turned into a super cargo plane with only internal cargo stowage
just might work from a economic point of view.

Pat