Skylon SSTO

Alex Terrell wrote:
Impressive some of the things communism achieved. Gnom strikes me as a
technology that would be worth looking at. If the military developed
it, it might be quite easy to put on an air launch.

It was just a ducted rocket. The performance (delta-v) was about the
same as a conventional rocket, but it made the launch vehicle physically
smaller (presumably by reducing the oxidiser needed). They were only
interested in it so it could fit onto a truck with a particular warhead.

Your always looking for performance with rockets; they only barely make
orbit really.

Performance-wise ducted rockets (and ramjets) don't get you anywhere-
the extra Isp of the duct gains you quite a bit early on in the burn,
but towards the end the dead weight of the duct and such like costs you
almost exactly everything you gained.

Stick a precooler on it, and it might work; that would reduce the weight
of the duct and extend the Mach. So you gain more acceleration at high
Isp and you don't lose as much when you burn for orbit.

Jochem Huhmann wrote:


I think it's really curious that all renderings of LAPCAT don't show any
windows, which is quite odd for passenger transport. When you compare
LAPCAT to Skylon (which is quite similar in overall layout) you will
immediately see the reason for that omission: Where do you put 300
passengers in a craft which is almost all fuel tanks? I guess they don't
know where to put them, too.


I think they are in the mid section over the wing, with LH2 tanks ahead
of and behind them.
You can see the entry door over the wing in this drawing:
http://www.reactionengines.co.uk/ima..._Side_1280.jpg
The problem with windows would be weight - to take the temperatures the
exterior will reach in flight, they might have to be made from quartz
glass like on the SR-71, and the weight would be prohibitive.
The passengers would see outside via closed circuit TV... but I'm a
little queasy about not having the crew being able to see outside except
by television.
If there _is_ a crew... when this concept was played around with for
HOTAL* the passengers were going to be put aboard in a pressurized
cylinder, and the whole flight would be automated.
Yeah, I'd trust that.
Note that the three hundred people are going to board and depart via a
single door (views from the far side show no door), and that this
aircraft comes nowhere near meeting international standards for how fast
its passengers can be evacuated in a emergency.
It's little details like that which hint that this team is a lot more
about dreams than reality.
But big dreams are nothing new to small British aircraft firms; behold
the mighty Saunders-Roe P.192 seaplane, lugging its 1,000 passengers
around with its 24 Conway engines:
http://i9.photobucket.com/albums/a94...r/3c15450a.jpg
http://i9.photobucket.com/albums/a94...r/b27263df.jpg
http://i9.photobucket.com/albums/a94...r/scan0015.jpg

* Note correct spelling this time. ;-)

Pat

Fred J. McCall wrote:

Isn't that pretty much true of any aircraft? An airframe failure will
kill you. It doesn't matter how fast or slow you're going. It's that
fall with bits coming off that gets you...



I flew on a Soviet Il-62 with a screw missing from its top wing access
panel and a leaking emergency escape hatch (that I was sitting right
next to- frost covering, hissing noise, and all.)
At those Mach numbers and as lightly built as this aircraft is going to
have to be to work, if something goes even slightly wrong that causes it
to diverge from its intended flightpath it's going to come apart almost
instantly. It's got all the structural toughness of the Space Shuttle or
the Hindenburg.

Pat

Fred J. McCall wrote:
You did notice that this is by a bunch of moist behind the ears
CAYdets, right?


Space cadets.
It would be fun to track down all of their careers after that, wouldn't it?

Pat

Pat Flannery wrote:


* Note correct spelling this time. ;-)

HOTOL, not HOTAL!
I'll get this right yet. :-)

Pat

Jochem Huhmann wrote:
But in some cases you *can* be lucky, regardless of height. There was a
case in the 70ties or so of a 17 years old german girl in a plane over
the Amazonas which desintegrated mid-air. She fell and survived the fall
injured but alive. After looking for her mother (who also was on the
plane) but not finding anything she decided to follow a little creek,
figuring that little creeks lead to larger creeks and larger creeks lead
to rivers and rivers lead to people. 14 days later (!) she arrived at a
hut of some wood-workers who found her after returning from work and
transported her to a settlement with a boat along the river. She's now a
biologist somewhere in Germany. True story.


We had a story in one of our grade school readers of a RAF bomber
crewman whose plane was destroyed at night over Germany and who fell
minus his parachute into a snow covered coniferous forest; although
falling through the tree's branches scratched and cut him, they slowed
him enough so that he survived hitting the snow-covered ground under
them with just some bruises and sprains. He ended up in a POW camp and
was considered one mighty lucky individual. :-)

Pat

Pat

Paul F. Dietz wrote:

A couple of cases of aviators in WW2 also. I recall reading
about one in grade school (fell out of an allied bomber without
his parachute, but went through the branches of a pine tree
into a snow drift, and only broke his legs. The germans, once
they verified his story, treated him as a kind of curiosity/good luck
charm/pet.)

You didn't go to a Catholic primary School did you?
Because we obviusly read the same book.
I didn't remember the broken legs part, but apparently this story sticks
with everyone who reads it. :-)
Did you later read about the two National Weather Service guys in the
glider that had its wings torn off in the thunderstorm and bailed out
inside the storm only to get caught in the updraft and sucked up to very
high altitude inside the storm?

Pat

Rand Simberg wrote:

Well, it beats concrete...


Or having an aeroplane fall on your horse:
http://www.earlyaviator.com/archive/....Car.Crash.jpg

Pat

Ian Woollard wrote:

It was just a ducted rocket. The performance (delta-v) was about the
same as a conventional rocket, but it made the launch vehicle
physically smaller (presumably by reducing the oxidiser needed). They
were only interested in it so it could fit onto a truck with a
particular warhead.

They got very good at solid-fueled ramjets; they made a solid rocket
propellant that was very low in oxidizer content so that it would only
burn slowly but the exhaust products of its combustion would the mix
with air brought in through ducts on the vehicle's exterior and undergo
secondary combustion to generate thrust. They first used used this
technology on the SA-6 "Gainful" SAM, and have incorporated it in other
missiles since then.
What was really clever about the SA-6 was that it used a solid fuel
rocket motor built into the ramjet duct; once this had burnt out its
casing formed the inside of the ramjet's exit nozzle.


Your always looking for performance with rockets; they only barely
make orbit really.

Performance-wise ducted rockets (and ramjets) don't get you anywhere-
the extra Isp of the duct gains you quite a bit early on in the burn,
but towards the end the dead weight of the duct and such like costs
you almost exactly everything you gained.


That's why Gnom used it as a jettisonable stage.

Pat