Henry, Rocket Racing League,RRL, was far less ambitious than a suborbital
effort. Kind of silly in my opinion but I'll work on any rocket project
that pays the bills, even some that don't. Xcor was involved too and had
their own version of a pump but not electric.
RRL died on the vine anyway before reaching fruition approx 12 years ago.
Ken
On Mon, Jul 25, 2022 at 9:40 PM Henry Spencer <hspencer@xxxxxxxxxxxxx>
wrote:
On Mon, 25 Jul 2022, Bill Bruner 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 depends hugely on what your goals are.
If your goal is simply to fly a rocket-powered airplane, then yes,
starting with an existing airplane makes a whole lot of sense, especially
since the experimental-airplane regulatory situation is *vastly* less
difficult than its rocketry counterpart. But remember that you'll be
limited by what that airplane can do; you can't even make it go supersonic
by just supplying more thrust. (For one thing, it probably isn't strong
enough to survive that. Not to mention being the wrong shape and having
the wrong controls, among other issues.)
If your goal is to get into space (briefly), which is basically what the
original question was about, *and* you think you want to do that by
building a high-performance rocket-powered airplane, then starting with a
low-performance one based on an existing airplane probably makes sense.
It'll teach you a lot about the practical aspects of operating a rocket
airplane, for sure, and if it's done properly and well, it will get you
considerable credibility with regulatory authorities (which is not to be
sneezed at). But to actually reach your goal, you'll still be facing the
daunting problem of designing and building a high-supersonic aircraft, and
the flight experience with the low-performance one won't help much with
that. Even the regulatory situation changes: when thrust exceeds lift
for more than half the powered ascent, *it's not an airplane any more*,
even if it resembles one -- it's a "suborbital rocket" and the spaceflight
rules and regulatory process apply.
If your goal is to get into space, but you're not sold on doing it with
something that looks like an airplane, then operating a rocket airplane
may be just a wasteful diversion of effort. Armadillo built the
propulsion system for one of the Rocket Racer designs, and that experience
just reinforced their belief that HTHL is "several times harder" than
wingless VTVL. "If it doesn't look like a flying propellant tank, it's
not a very efficient rocket."
(Even XCOR, committed to the wings-and-runway approach to suborbital
spaceflight, did find that "this *isn't* just like an airplane" -- too
many things are different, it's easy to find yourself operating in regimes
where there is little past experience and little off-the-shelf hardware.)
First decide what you want to do. Then consider whether building and
operating a rocket-powered light airplane is really on that path, or even
(to swipe a phrase from Jeff Greason) "within 30 degrees of your base
course".
Henry
