That's a fun idea that I've considered as well, though I see one possible
issue. Most of the places you can easily fly interesting experimental
rockets are in the desert, which tend to be covered in flammable brush. It
would be a pity to nail a retrorocket landing only to land in a fire you
just started.
My scheme was to use a rear drogue or ballute and have the retro mounted in
the nose. That way it can be mounted on axis, the mass of the
retrorocket contributes to flight stability, and the drogue or streamer
doesn't have to overwhelm the fins.
I'm sure someone has done it at FAR at some point. There was a guy flying a
ramrocket there a few years ago, would have made a good topic of
discussion.
Ben
On Sunday, January 10, 2016, David Summers <dvidsum@xxxxxxxxx> wrote:
If I were trying to stretch the current state of the art in amateur rocket
landings, I'd go for this:
1. At (or after) apogee, pop a streamer from the nose, keep the rocket
otherwise intact. This merely keeps the rocket nose up on the way down,
and makes it subsonic.
2. Make a really good altitude detection system, and 5 feet off the ground
fire a solid landing rocket that brings the rocket as close as possible to
1 foot altitude, zero velocity.
That seems feasible, though difficult. Honestly from what I've seen I
don't think it would be that much worse than a parachute in reliability.
We seem to see a lot of parachute failures!
(I'm working on other things, but this is what I would build.)
Thanks!
-David Summers
On Sun, Jan 10, 2016 at 1:18 PM, rebel without a job <
rebelwithoutajob@xxxxxxxxxxx
<javascript:_e(%7B%7D,'cvml','rebelwithoutajob@xxxxxxxxxxx');>> wrote:
From an amateur perspective, parachutes seem to be the only
cost-effective solution. Active rocket landings imply a great number of
technologies that are outside the capabilities of all but the most
well-heeled amateurs. The hardest one would be a gimballed, restartable,
deep-throttleable engine. Add to that the control and lubrication of the
gimbal system, and associated hydraulic actuation and pumping, and I think
we may be out of the amateur range altogether.
At this point, building a flying biprop with some aerodynamic controls
seems to be the upper edge of the amateur capability.
A guided parachute seems wonderful. I’d prefer a choppy landing near me
to a choppy landing in a distant, unknown location. It also has the
benefit of being usable and testable by the large group of people flying
high-power solids, thus speeding development cycles.
For recovery of the motors, I think a few inflatable airbags may be
optimal. They would cushion the landing well enough to protect the tail
end from the initial impact. Depending on the lateral velocity, the
airframe may be damaged from a subsequent tip over. Reliable recovery of
airframe and propulsion system does seem difficult though.
On Jan 10, 2016, at 11:28 AM, Uwe Klein <uwe@xxxxxxxxxxxxxxxxxxx<javascript:_e(%7B%7D,'cvml','uwe@xxxxxxxxxxxxxxxxxxx');>> wrote:
significant cost in weight.)Parachutes provide for a rather choppy landing
that may not be over when you have touched down.
( And the payload tends to require carefull packing that comes at
used.
Dragchutes should work well for energy management.
But for the actual landing something more sophisticated needs to be
You require point landing and very low speed final approach.ground)
( Rocket engines are not designed or being dropped asswards on the
We've seen that an active rocket landing works.
