The aircraft I worked with was a production Velocity. It had both LOx and
Alcohol spheres in the back seat pressurized with GHe.
Just before the Rocket Racing Leagues was disbanded I began work on
replacing the fuel sphere with the wing tanks
and pumping the fuel directly to the rocket engine using a positive
displacement gear pump driven by an electric brushless motor.
It only had to run for a few minutes so the batteries wouldn't have weighed
that much, much less than the SS sphere and part of the pressurant system.
Too bad this idea didn't reach fruition, I think it would have
significantly increased the performance of the vehicle particularly later
on once the LOx pressurizing system would have been replaced with a pump
too.
Ken
On Mon, Jul 25, 2022 at 6:06 PM Bill Bruner <bill@xxxxxxxxxx> wrote:
The lay up is to put a liquid engine with a throttle in an existing
airplane and get an experimental permit from the local FSDO.
It's been done (see EZ Rocket and the various Rocket Racers).
If you want to go vertical, just pull the nose up.
Rick Searfoss came close to vertical in Bridenstine's airplane at OSH 13
years ago, as seen at about 1:30 into this video
<https://youtu.be/HlH0eMGM2jQ>.
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On Sat, Jul 23, 2022 at 10:55 PM Henry Spencer <hspencer@xxxxxxxxxxxxx>
wrote:
On Sat, 23 Jul 2022, Matthew JL wrote:
...with the slow ramp-up of more powerful and technologically capable
liquid engines (I am optimistic about the future of Half Cat and
derivatives even in the face of regulatory challenges), it seems like
inevitably someone's going to build an engine that warrants putting a
person on top of it.
Armadillo Aerospace was building engines (and experimental vehicles) with
an eye on that twenty years ago, in fact. And yes, they were an amateur
group in the beginning: "I'm running this endeavour like a rich hobbyist
rather than a poor aerospace company." -- John Carmack, 2002. (Although
they gradually started paying people as revenue started coming in and the
workload got higher.) They came close, and might have succeeded if they
hadn't hit stubborn supply-chain problems with their chosen oxidizer
(peroxide).
So let's look ahead in the hobby another 10-15 years and imagine what
that might look like. Capsule-and-booster as tradition warrants (and
Copenhagen Suborbitals is doing)? A spaceplane in the vein of the X-15
or SS1/SS2?
John Carmack thought back then, and last I heard still did, that a
one-piece rocket with vertical takeoff and landing was the right way to
go. Adding either separation events or wings adds a lot of complexity;
making either one pay for itself is harder than it looks. The less
mechanical and aerodynamic complexity, the better. (In particular,
designing supersonic airplanes, especially ones with a large Mach-number
range, is *hard*. If Burt Rutan had trouble with it -- he did -- so will
you. A design concept that can mostly ignore the atmosphere is a big
simplification.)
That said, there is undoubtedly more than one way to do it...
What will bridge the gap between the amateur space now and something as
ludicrous as homebuilt spacecraft?
Actually, homebuilt spacecraft have been a reality for over 60 years --
see the amateur-radio satellites, starting with OSCAR 1 in 1961.
A homebuilt space *vehicle* would be a much bigger job, yes. Probably
the
key requirement for bridging *that* gap is non-technical: somebody on
the
team has to be at least a little bit rich, or have a patron who is.
Armadillo cost John about half a million a year for most of its
decade-plus life. It could have been done for less, perhaps much less,
but even with all-volunteer labor, there are a good many things that
require cash up front if you want to get results in a reasonable amount
of
time. And most of the volunteers will gradually lose interest and leave
if the project never seems to get anywhere.
(Even an amateur project needs a realistic budget plan -- one in which
required outlays don't exceed likely financial resources. "Realistic"
means no step in the middle saying "and then a miracle happens". Even
rough estimates can tell you when you're being unrealistic -- it's not
going to cost *less* than you think...)
Don't forget the Regulatory Affairs aspect. Quoth FAA regs, 14CFR1.1
(emphasis added): "'Amateur rocket' means an *unmanned* rocket that...".
As soon as it's manned, it loses its amateur status and (in principle)
you
have to cope with the full regulatory process. This can be onerous even
if you manage to negotiate simplifications, e.g. via "alternative means
of
compliance providing an equivalent level of safety" clauses. And don't
underestimate the effort required, or the fact that it's not fun -- it
wasn't an accident that the Regulatory Affairs guy at Armadillo was the
first one to start getting paid...
Henry
