Towed Booster Stability

If a rocket booster had a towline attach point at the extreme
rear of the vehicle, it seems that a towed upper stage would
provide dynamic stability in the verticle orientation. The attach
point would have to avoid excessive exhaust impingment.

This is just a thought on providing a near SSTO with a BDB
launch assist platform without some of the stacking and stageing
problems. If the booster is as stable in tow as I think possible,
then minimal control system would be needed to make it
a real dumb booster with smart results.

"johnhare" wrote in news:2cKEc.8288$uK.604
@twister.tampabay.rr.com:

If a rocket booster had a towline attach point at the extreme
rear of the vehicle, it seems that a towed upper stage would
provide dynamic stability in the verticle orientation. The attach
point would have to avoid excessive exhaust impingment.

How do you propose to protect the towline(s)?

--Damon

Damon Hill writes:

"johnhare" wrote in news:2cKEc.8288$uK.604
:

If a rocket booster had a towline attach point at the extreme
rear of the vehicle, it seems that a towed upper stage would
provide dynamic stability in the verticle orientation. The attach
point would have to avoid excessive exhaust impingment.

How do you propose to protect the towline(s)?


Er, OK, if *two* rocket boosters carried the towed upper stage together,
on a line attached under the dorsal guiding fins...


More seriously, if your single rocket booster has multiple engine or
nozzles clustered about a centerline, you can cant the nozzles slightly
outward to provide plume clearance without too much in the way of
cosine losses.


--
*John Schilling * "Anything worth doing, *
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(John Schilling) wrote in
:

Damon Hill writes:

"johnhare" wrote in news:2cKEc.8288$uK.604
:

If a rocket booster had a towline attach point at the extreme
rear of the vehicle, it seems that a towed upper stage would
provide dynamic stability in the verticle orientation. The attach
point would have to avoid excessive exhaust impingment.

How do you propose to protect the towline(s)?


Er, OK, if *two* rocket boosters carried the towed upper stage
together, on a line attached under the dorsal guiding fins...

Now THAT's going to be interesting to watch, three objects at
multi-mach speeds in close formation...tied together. Liftoff is
going to be fun, too.

More seriously, if your single rocket booster has multiple engine or
nozzles clustered about a centerline, you can cant the nozzles
slightly outward to provide plume clearance without too much in the
way of cosine losses.

It's just too much trouble. Seriously, let's stick to one
mechanically attached assembly; multiple parts flying in intimate
formation as it were.

--Damon

"Damon Hill" wrote in message
. 134...
(John Schilling) wrote in
:

Damon Hill writes:

"johnhare" wrote in news:2cKEc.8288$uK.604
:

If a rocket booster had a towline attach point at the extreme
rear of the vehicle, it seems that a towed upper stage would
provide dynamic stability in the verticle orientation. The attach
point would have to avoid excessive exhaust impingment.

How do you propose to protect the towline(s)?


Er, OK, if *two* rocket boosters carried the towed upper stage
together, on a line attached under the dorsal guiding fins...

Now THAT's going to be interesting to watch, three objects at
multi-mach speeds in close formation...tied together. Liftoff is
going to be fun, too.

Liftoff is down a runway on launch dollys. No wings.

More seriously, if your single rocket booster has multiple engine or
nozzles clustered about a centerline, you can cant the nozzles
slightly outward to provide plume clearance without too much in the
way of cosine losses.

It's just too much trouble. Seriously, let's stick to one
mechanically attached assembly; multiple parts flying in intimate
formation as it were.

Anyone going to take a shot at the orriginal question? I have some
reason to believe there would be advantages for some systems.

--Damon

"johnhare" wrote in message .. .
If a rocket booster had a towline attach point at the extreme
rear of the vehicle, it seems that a towed upper stage would
provide dynamic stability in the verticle orientation. The attach
point would have to avoid excessive exhaust impingment.

Nope. Basically the pendullum fallacy:

http://www.geocities.com/jim_bowery/pendrock.html

I actually tried making model rockets with both fixed and flexible
towed payloads before I understood this.

John Carmack
www.armadilloaerospace.com

"John Carmack" wrote in message
om...
"johnhare" wrote in message
.. .
If a rocket booster had a towline attach point at the extreme
rear of the vehicle, it seems that a towed upper stage would
provide dynamic stability in the verticle orientation. The attach
point would have to avoid excessive exhaust impingment.

Nope. Basically the pendullum fallacy:

http://www.geocities.com/jim_bowery/pendrock.html

I actually tried making model rockets with both fixed and flexible
towed payloads before I understood this.

Checked your link. I knew fixed wouldn't work, (Willey Ley; Rockets
Missles, and Space Travel 1951) I was just considering the very flexible
case. Obviously, it was the level of effort you are expending on control
issues that triggered the thought.

John Carmack
www.armadilloaerospace.com

"johnhare" wrote in message
...
This is just a thought on providing a near SSTO with a BDB
launch assist platform without some of the stacking and stageing
problems.

What stacking and staging problems? Stacking a booster takes just a few
days. When's the last time a mature rocket design had problems staging? I
can think of one Delta II that had an odd separation problem with an SRM
that led to loss of mission, but that's about it. The Japanese separation
problem not long ago was due to an immature design.

-Kim-

"Kim Keller" wrote in message
.. .

"johnhare" wrote in message
...
This is just a thought on providing a near SSTO with a BDB
launch assist platform without some of the stacking and stageing
problems.

What stacking and staging problems? Stacking a booster takes just a few
days. When's the last time a mature rocket design had problems staging? I
can think of one Delta II that had an odd separation problem with an SRM
that led to loss of mission, but that's about it. The Japanese separation
problem not long ago was due to an immature design.

On the other end of the experience spectrum from you, These issues concern
me with the immature concepts that should be showing up directly. The
equipment
for stacking is an expense as well as the man hours required on a high
flight rate
vehicle. Staging is frequently mentioned here as a problem area with
recontact
and seperation problems high on the list. OTOH, I do seem to have a history
of
attempting to solve non-problems.

I am considerably more interested in the new concepts under consideration
than
the current LVs. As these new concepts evolve, a variety of means to reduce
cost and improve safety need to be explored. The cost of refuting the one I
threw
out here probably totaled $0.50 in electricity and a few hours of the
readers time.
Those costs are voluntary and can be eliminated on the individual level by
killfiling
me. If we throw out a hundred ideas at this cost, and one of them leads to
usefull results, it is a net win for the start up space community. Also
the negative
answers inform for future ideas. You; stacking and staging=not problems.
John
Carmack; idea flawed in concept. Attention can be focused on more productive
problems.

-Kim-

In article ,
Kim Keller wrote:
...When's the last time a mature rocket design had problems staging? I
can think of one Delta II that had an odd separation problem with an SRM
that led to loss of mission, but that's about it. The Japanese separation
problem not long ago was due to an immature design.

Since today's rockets seldom see huge production batches between design
changes, any failed rocket can be accused of being immature. This is
circular: if it works it's mature, if it doesn't it's immature! It's
fairer to just count all the failures, at least in orthodox modern
programs where the customers and stockholders are assured ahead of time
that everything has been analyzed to death, failures are most unlikely,
and so there is no need for a flight-test program.

Don't forget the second Pegasus XL (interstage ring initially failed to
separate, crippling nozzle gimbaling, and by the time it did finally fall
off, the guidance system had gotten hopelessly confused), the first PSLV
(attitude transients during separation of second stage confused guidance),
and the 1999 IUS failure (electrical connector didn't separate due to
thermal tape, preventing proper second-stage operation). IUS was mature
beyond doubt; the other two were upgraded vehicles, but the failures were
in areas with extensive design heritage from earlier ones.
--
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