Talk-Polywell.org

This is interesting. I wonder why I've never heard of it before now. The system uses 64 identical engines in parallel in 3 stages, 48, 12, 4 engines for stages 1, 2, and 3 in order to launch 2 tons into orbit. Each liquid fueled engine, complete with fuel tank (about 10 inch dia.) is very, very simple, but throttalable with one moving part, a fuel valve. 6,000 static rocket engine tests and 16 single stage qualification tests achieving up to 50,000 ft altitude were made to prove the concept as feasible. It was canceled due to politics, not for fear of an ICBM for every terrorist, but because it was a German company during the cold war, and Russia really didn't want the Germans to have big rockets.

http://en.wikipedia.org/wiki/OTRAG_(rocket)
http://en.wikipedia.org/wiki/OTRAG

For some reason your post is empty on my end. I will reproduce its content below for anyone else who can't see anything.


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This is interesting. I wonder why I've never heard of it before now. The system uses 64 identical engines in parallel in 3 stages, 48, 12, 4 engines for stages 1, 2, and 3 in order to launch 2 tons into orbit. Each liquid fueled engine, complete with fuel tank (about 10 inch dia.) is very, very simple, but throttalable with one moving part, a fuel valve. 6,000 static rocket engine tests and 16 single stage qualification tests achieving up to 50,000 ft altitude were made to prove the concept as feasible. It was canceled due to politics, not for fear of an ICBM for every terrorist, but because it was a German company during the cold war, and Russia really didn't want the Germans to have big rockets.

http://en.wikipedia.org/wiki/OTRAG_(rocket)
http://en.wikipedia.org/wiki/OTRAG [/quote]
>>

edit- Weird! I can't see anything in this post either.

Cheep, mass producable rocket.
I wonder why I've never heard of it before now. The system uses 64 identical engines in parallel in 3 stages, 48, 12, 4 engines for stages 1, 2, and 3 in order to launch 2 tons into orbit. Each liquid fueled engine, complete with fuel tank (about 10 inch dia.) is very, very simple, but throttalable with one moving part, a fuel valve. 6,000 static rocket engine tests and 16 single stage qualification tests achieving up to 50,000 ft altitude were made to prove the concept as feasible. It was canceled due to politics, not for fear of an ICBM for every terrorist, but because it was a German company during the cold war, and Russia really didn't want the Germans to have big rockets.

Hmm - the links are not allowed?

http://en.wikipedia.org/wiki/OTRAG_(rocket)
http://en.wikipedia.org/wiki/OTRAG

It doesn't work with url tags, but works without them. Copy and paste the first link, _(rocket) is part of the url.

Aero wrote:http://en.wikipedia.org/wiki/OTRAG_(rocket)
http://en.wikipedia.org/wiki/OTRAG

It doesn't work with url tags, but works without them. Copy and paste the first link, _(rocket) is part of the url.

Can you still edit your original post?

Also, this:
http://www.astronautix.com/lvs/otrag.htm

Aero wrote:Cheep, mass producable rocket.
I wonder why I've never heard of it before now. The system uses 64 identical engines in parallel in 3 stages, 48, 12, 4 engines for stages 1, 2, and 3 in order to launch 2 tons into orbit. Each liquid fueled engine, complete with fuel tank (about 10 inch dia.) is very, very simple, but throttalable with one moving part, a fuel valve. 6,000 static rocket engine tests and 16 single stage qualification tests achieving up to 50,000 ft altitude were made to prove the concept as feasible. It was canceled due to politics, not for fear of an ICBM for every terrorist, but because it was a German company during the cold war, and Russia really didn't want the Germans to have big rockets.

During the Cold War, neither of the superpowers wanted major space programs by other players, and since the West Germans were the designated speed bump on the wrong side of the Fulda Gap, they were easy to intimidate. After all, no town in Germany was more than ten kilotonnes distant from any other.

See also:
http://www.astronautix.com/lvs/blaarrow.htm

OTRAG was a topic of much interest in the L5 News for a while and then it disappeared. Oh whell!

I heard about it a while ago. It did not interest me that much. My main interest is RLVs, not ELVs.

I didn't know this system also, but (in a smaller scale) it looks very similar to what SPACEX is doing.

Get a proven rocket technology module, use it as a base of your rockets and add more modules to increase payload.

Otrag modules are just too small. A 10 Tons to LEO with this system is estimated to need a 1000 T rocket at launch. A Spacex Falcon 9 is less than 350 T at launch for the same payload to LEO.

Skipjack wrote:I heard about it a while ago. It did not interest me that much. My main interest is RLVs, not ELVs.

Absent nuclear power of some sort, or breakthrough physics, ELVs are the way to go.

Giorgio wrote:Otrag modules are just too small. A 10 Tons to LEO with this system is estimated to need a 1000 T rocket at launch. A Spacex Falcon 9 is less than 350 T at launch for the same payload to LEO.

Irrelevant. What matters is cash cost, not mass ratio efficiency. The cult of technical efficiency uber alles = "cost control" is a delusion spread by NASA and the engineers who want ever better toys instead of "affordable and good enough." Pressure-fed diesel and nitric acid are dead cheap and brain dead mechanically simple; no complex turbopumps to fail. OTRAG is one of the most elegant LCLV ideas ever conceived.

http://www.dunnspace.com/

http://www.bernd-leitenberger.de/otrag1.shtml
http://www.bernd-leitenberger.de/img/ot ... gleich.gif
http://www.bernd-leitenberger.de/img/ot ... nzept.jpeg

djolds1 wrote:

Skipjack wrote:I heard about it a while ago. It did not interest me that much. My main interest is RLVs, not ELVs.

Absent nuclear power of some sort, or breakthrough physics, ELVs are the way to go.

Giorgio wrote:Otrag modules are just too small. A 10 Tons to LEO with this system is estimated to need a 1000 T rocket at launch. A Spacex Falcon 9 is less than 350 T at launch for the same payload to LEO.

Irrelevant. What matters is cash cost, not mass ratio efficiency. The cult of technical efficiency uber alles = "cost control" is a delusion spread by NASA and the engineers who want ever better toys instead of "affordable and good enough." Pressure-fed diesel and nitric acid are dead cheap and brain dead mechanically simple; no complex turbopumps to fail. OTRAG is one of the most elegant LCLV ideas ever conceived.

http://www.dunnspace.com/

http://www.bernd-leitenberger.de/otrag1.shtml
http://www.bernd-leitenberger.de/img/ot ... gleich.gif
http://www.bernd-leitenberger.de/img/ot ... nzept.jpeg

There is a paper floating out there (link on NSF) that details design shortcomings of OTRAG, which include, among others, excessive pogo, as well as excess propellant in the modules on one side due to the roll control system, which will cause mass destabilization.

While we're on the subject of Rockets, what would you say about throwing away the Turbo Pump? I've been watching these guys for years who've got an idea that I can't really see anything wrong with. It appears to work. If it works as promised, it seems you ought to be able to boost payload quite a bit.

The pump will also increase the performance and capability of in-space propulsion systems such as will be required for the crew exploration vehicle(CEV), by allowing for greater fuel capacity for a given tank mass and higher engine pressures. (see pressure fed mass savings calculations 101 KB .pdf)

Here's a diagram of their idea.





And a picture of their first testable designs.





And a picture of one of their functional pumps.




Some of their test launches.





And their URL

http://www.flometrics.com/rockets/rocke ... etpump.htm

Yeah the Flometrics guys have some nice stuff. Masten used one of their piston pumps on an old model, they will likely reuse it on an upcoming design. Piston pumps are the fad among NewSpace types, XCor has their own piston pump designs for EZ Rocket and Lynx.

djolds1 wrote:

Giorgio wrote:Otrag modules are just too small. A 10 Tons to LEO with this system is estimated to need a 1000 T rocket at launch. A Spacex Falcon 9 is less than 350 T at launch for the same payload to LEO.

Irrelevant. What matters is cash cost, not mass ratio efficiency.

More useless weight to lift = more cost, and we are talking 3 times more weight here for same final payload to LEO.

The solution is elegant, but is not much different from what SPACEX is doing on a bigger/more economic scale.

Giorgio wrote:

djolds1 wrote:

Giorgio wrote:Otrag modules are just too small. A 10 Tons to LEO with this system is estimated to need a 1000 T rocket at launch. A Spacex Falcon 9 is less than 350 T at launch for the same payload to LEO.

Irrelevant. What matters is cash cost, not mass ratio efficiency.

More useless weight to lift = more cost, and we are talking 3 times more weight here for same final payload to LEO.

No. More weight to lift = less efficient, not more cost. Not the same thing. Efficiency is often very more costly; diminishing returns.

Giorgio wrote:The solution is elegant, but is not much different from what SPACEX is doing on a bigger/more economic scale.

Pressure fed designs have been the obvious affordable way to go for large scale space access since the '60s. But they do not serve the interests of an oligopolistic cartel of government contractors or their sole-source single bureaucracy employer.

djolds1 wrote:

Giorgio wrote:

djolds1 wrote:Irrelevant. What matters is cash cost, not mass ratio efficiency.

More useless weight to lift = more cost, and we are talking 3 times more weight here for same final payload to LEO.

No. More weight to lift = less efficient, not more cost. Not the same thing. Efficiency is often very more costly; diminishing returns.

I was just trying to make the concept simple.
Anyhow, as far as space launch is concerned, the equation "More useless weight to lift = more cost per ton in LEO" holds pretty much true.

djolds1 wrote:Pressure fed designs have been the obvious affordable way to go for large scale space access since the '60s. But they do not serve the interests of an oligopolistic cartel of government contractors or their sole-source single bureaucracy employer.

I do not completely agree.
Pressure fed design do have some limitations on flow rate, which means that they cannot achieve the same high thrust as turbo-pumps. I am sure that material and technological advancements will smooth some or all of these limitations, but for now Turbo-pumps are difficult to beat.
Once in orbit pressure fed designs have been an almost standard choice from all manufacturers.

It might be of interest for you that the second stage engine of SPACEX Falcon1 is a pressure-fed Engine:
http://spacex.com/falcon1.php