I've thought about putting a pair of fins/vanes, pointing in opposite
directions, just out side the expansion cone.
Then a single servo could move one or the other of the vanes into the gas
stream as much as is needed
for roll control, No input needed then no loss of efficiency, excess drag
or heating...
On Wed, Jun 6, 2018 at 7:48 PM, Craig Fink <webegood@xxxxxxxxx> wrote:
The cheapest, lightest, most economical, easiest way to achieve roll
control of a "fin less tubular rocket using a single center line gimbals
thrust chamber" is to add one electric servo and fin at the end of the
engine bell. It will give you unlimited roll control Impulse with a maximum
roll torque sized by the fin size. A supersonic airfoil should be used and
balanced to limit electric servo motor actuator size.
It only works if your thrusting.
On Wed, Jun 6, 2018 at 7:12 PM Paul Breed <paul@xxxxxxxxxx> wrote:
The Single axis gimbal per tube makes everything easy....and is for sure
the correct solution long term.
Some of the outer tubes might not need gimbals...
On Wed, Jun 6, 2018 at 4:53 PM, Henry Vanderbilt <
hvanderbilt@xxxxxxxxxxxxxx> wrote:
On 6/6/2018 2:25 PM, Henry Spencer wrote:
On Wed, 6 Jun 2018, Paul Breed wrote:
Fly and learn....Looking to build up an OTRAG staging experiment.
Trying to decide if the central core is one, ,two, three or four tubes.
One obvious question to ask yourself, then, is how much effort you want
to invest in problems that are unique to the core and won't appear in the
larger configurations. If the answer is "not much", you probably want
three or four tubes in the core, so you can use the same control methods
for it as for the bigger bundles. Not having to do single-tube roll
control opens up the control options considerably, especially if you don't
have to do both pitch and yaw in a single-tube configuration either (which
permits, e.g., differential throttling or single-axis gimbals).
I'd be inclined against differential throttling for an OTRAG-type
vehicle. My impression is that valves get expensive, heavy, and/or
unreliable the instant you ask for anything beyond simple shut-to-open from
them. (And sometimes even than.)
At a minimum two valves per tube (prevalves of some sort are generally a
big plus for routine operations) an OTRAG-type vehicle probably needs to
lean heavily toward cheap, light, dirt-simple/reliable valves.
Henry (V)
--
Craig Fink
WeBeGood@xxxxxxxxx
