Carmack's Jet Vanes

I've been following the latest at Armadillo with some interest:
John Carmack's switched from a multi-engine vehicle to a vehicle with
one big engine controlled with Jet Vanes.

http://www.armadilloaerospace.com/n.x/Armadillo/Home/News?news_id=256"

Carmack says the jet vanes only subtract "a few percent" from the
engine due to drag, and there's small danger of them eroding in his
engine due to the lower temperatures than w/ traditional fuels.

Anybody heard of previous work done along these lines? Or is Armadillo
breaking some major new ground here? (I mean besides cost-wise.)

Any useful links would be appreciated.

Tom Merkle

Tom Merkle wrote:

[snip]
Anybody heard of previous work done along these lines? Or is Armadillo
breaking some major new ground here? (I mean besides cost-wise.)

I think the german A4/V2 rocket used jet vanes. So this is not really new.
The nice thing about the armadillo mixture is that it burns so cold that
you do not need exotic materials for the rudders. They look like steel.

(Tom Merkle) wrote:

Anybody heard of previous work done along these lines? Or is Armadillo
breaking some major new ground here? (I mean besides cost-wise.)

There's a lot of previous work on jet vanes, but it's all quite old.

D.
--
Touch-twice life. Eat. Drink. Laugh.

"Ruediger Klaehn" wrote in message
...
Tom Merkle wrote:

[snip]
Anybody heard of previous work done along these lines? Or is Armadillo
breaking some major new ground here? (I mean besides cost-wise.)

I think the german A4/V2 rocket used jet vanes. So this is not really new.
The nice thing about the armadillo mixture is that it burns so cold that
you do not need exotic materials for the rudders. They look like steel.



I think Goddard had a gyro-steered vane scheme on some of his rockets
(http://www.astronautix.com/graphics/g/god37van.jpg). I also seem to
remember seeing this kind of thing on Redstones
(http://www.boeing.com/history/bna/redstone.htm, V2 derivative?). I didn't
read far enough into Carmack's description to understand why they want to go
back to such a "retro" steering scheme.

JJ Robinson II
Houston, TX
****************
* JOKE *
****************
* SERIOUS *
****************
* SARCASTIC *
****************
* OTHER? *
****************

(Tom Merkle) writes:

I've been following the latest at Armadillo with some interest:
John Carmack's switched from a multi-engine vehicle to a vehicle with
one big engine controlled with Jet Vanes.

http://www.armadilloaerospace.com/n.x/Armadillo/Home/News?news_id=256"

Carmack says the jet vanes only subtract "a few percent" from the
engine due to drag, and there's small danger of them eroding in his
engine due to the lower temperatures than w/ traditional fuels.

Anybody heard of previous work done along these lines? Or is Armadillo
breaking some major new ground here? (I mean besides cost-wise.)

Any useful links would be appreciated.


If by "links" you mean the www type, there is a slight problem in that
all the groundbreaking work was done before the invention of the digital
computer, much less the internet. So no, it's not new. Werner von Braun
and his crew were aiming for the stars and hitting London with rockets
steered by jet vane (and burning hotter than Carmack's mixed monoprop)
before most of us were born.

It does mean, as with so much of the really good technology in this field,
that to make use of it you have to actually, physically, delve into old
dusty archives that nobody ever bothered to html-ize.


--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
* for success" *
*661-718-0955 or 661-275-6795 * -58th Rule of Acquisition *

Ruediger Klaehn wrote in message ...
Tom Merkle wrote:

[snip]
Anybody heard of previous work done along these lines? Or is Armadillo
breaking some major new ground here? (I mean besides cost-wise.)

I think the german A4/V2 rocket used jet vanes. So this is not really new.
The nice thing about the armadillo mixture is that it burns so cold that
you do not need exotic materials for the rudders. They look like steel.

We certainly aren't doing anything new -- jet vanes are literally the
oldest trick in the book for steering rockets, and they are still
commonly used for various tactical missiles. The disadvantages are
well known: slight loss of performance and erosion issues.

In our particular case, the disadvantages don't really matter. Anyone
stressing over a few percent performance in a suborbital vehicle
doesn't have their priorities in the right order, and our exhaust
temperatures are low enough that stainless steel can run forever in it
without any erosion.

The advantages are in practical matters like less plumbing, easier
checkout, and no need to make multiple engines behave identically.
Practical matters are often not appreciated by people not involved in
actual vehicle construction -- I have gotten literally dozens of
emails with suggestions of adding "a few more engines" for various
schemes.

We are making fast progress on a bigger jet vane system for the full
scale vehicle, so there is an excellent chance we will have that in
the air next weekend.

John Carmack
www.armadilloaerospace.com

(John Carmack) wrote:
The advantages are in practical matters like less plumbing, easier
checkout, and no need to make multiple engines behave identically.
Practical matters are often not appreciated by people not involved in
actual vehicle construction

I.E. the vast majority of the aerospace industry, professional,
semi-professional, garage, and amateur.

D.
--
Touch-twice life. Eat. Drink. Laugh.

(Derek Lyons) writes:

(John Carmack) wrote:
The advantages are in practical matters like less plumbing, easier
checkout, and no need to make multiple engines behave identically.
Practical matters are often not appreciated by people not involved in
actual vehicle construction

I.E. the vast majority of the aerospace industry, professional,
semi-professional, garage, and amateur.


Quite the opposite w/re the "garage" segment, by definition I should think.
Professional, yes, most aerospace engineering degrees belong to people who
will never touch flight hardware and never put ink to paper on working
drawings of flight hardware. Ditto amateur if we open that up to armchair
critics, which I suspect is where many of the comments Carmack refers to
are coming from.


--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
* for success" *
*661-718-0955 or 661-275-6795 * -58th Rule of Acquisition *

"John Carmack" wrote in message
om...


The advantages are in practical matters like less plumbing, easier
checkout, and no need to make multiple engines behave
identically. Practical matters are often not appreciated by people
not involved in actual vehicle construction -- I have gotten
literally dozens of emails with suggestions of adding "a few more
engines" for various schemes.


Speaking of fewer extra engines, I have wondered if instead of using
many maneuvering jets pointing in every direction, with extras for
redundancy. It might be easier to use but three or four with
directional control, say the capacity to individually point up, down,
left, right, and directly outward. With advances in control systems
over the past thirty years, I am no longer sure which approach would be
best.

Pete.

John Carmack wrote:

Ruediger Klaehn wrote in message ...
Tom Merkle wrote:

[snip]
Anybody heard of previous work done along these lines? Or is Armadillo
breaking some major new ground here? (I mean besides cost-wise.)

I think the german A4/V2 rocket used jet vanes. So this is not really new.
The nice thing about the armadillo mixture is that it burns so cold that
you do not need exotic materials for the rudders. They look like steel.

We certainly aren't doing anything new -- jet vanes are literally the
oldest trick in the book for steering rockets, and they are still
commonly used for various tactical missiles. The disadvantages are
well known: slight loss of performance and erosion issues.

In our particular case, the disadvantages don't really matter. Anyone
stressing over a few percent performance in a suborbital vehicle
doesn't have their priorities in the right order, and our exhaust
temperatures are low enough that stainless steel can run forever in it
without any erosion.

The advantages are in practical matters like less plumbing, easier
checkout, and no need to make multiple engines behave identically.
Practical matters are often not appreciated by people not involved in
actual vehicle construction -- I have gotten literally dozens of
emails with suggestions of adding "a few more engines" for various
schemes.

Another practical matter would be coupling between thrust-vector (or
aerodynamic) control systems, and propellant slosh, body-bending, or
other structural modes. (On SRAM we had digitally programmable notch
filters in the pitch and yaw commands going to the Fin Actuation
System.)

We are making fast progress on a bigger jet vane system for the full
scale vehicle, so there is an excellent chance we will have that in
the air next weekend.

Good luck!

John Carmack
www.armadilloaerospace.com