# Bob Truax's giant Sea Dragon launch vehicle concept (video)

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#### Winston

##### Lorenzo von Matterhorn
A fascinating interview video with Emory Stagmer, Northrop Grumman Senior software and systems engineer who describes Bob Truax's giant, but designed to be super simple Sea Dragon launch vehicle concept from the 60s in detail. BTW, note the valid critique of winged reusable launch vehicles:

Bob Truax's Sea Dragon

VAXHeadroom (Emory Stagmer) joins us in-studio to talk about the old Saturn V competitor: Sea Dragon. Capable of lofting 1.1 million LBS to Low Earth Orbit, this 1/2 submarine 1/2 rocket system would dwarf anything humans have ever built to date. What is it and how did it work?

How loud?: 165 dB at five miles, one of the several reasons it would have been launched at sea. The rocket would have been able to carry a payload of up to 550 metric tons (1.1 million pounds) into low Earth orbit, approximately half that to the moon. Payload costs were estimated to be between $59 to$600 per kg.

https://en.wikipedia.org/wiki/Sea_Dragon_(rocket)

Another great interview:

Emory Stagmer Future of Small Sats Interview Segment

Watching that led me to this newish propulsion tech which he said was extremely promising:

Iodine Propellant Space Propulsion

#### Nytrunner

##### Pop lugs, not drugs
TRF Supporter
Just saw this and was going to start a thread, but figured I'd just add to this one.

This thing just doesn't seem feasible. Incredible concept though

#### dhbarr

##### Amateur Professional
BDB is actually fairly workable, at least on paper. Requires no exotic materials or techniques.

Probably made a lot more sense before we managed to miniaturize so many components, though.

#### jazzviper1

##### Well-Known Member
The combustion instability problems would be mind boggling. The F-1 took years to resolve that problem.

#### dhbarr

##### Amateur Professional
The combustion instability problems would be mind boggling. The F-1 took years to resolve that problem.
Most definitely, but supercomputers and CFD make each test run orders off magnitude more useful for redesign iterations.

#### markkoelsch

##### Well-Known Member
Can you imagine the test stand needed to test the motor? 80 million pound of thrust would push the structural engineering of the stand to ridiculous levels.

#### neil_w

##### Good at some things
TRF Supporter
That's a great video, thanks for sharing.

#### dhbarr

##### Amateur Professional
Can you imagine the test stand needed to test the motor? 80 million pound of thrust would push the structural engineering of the stand to ridiculous levels.
Burj Khalifa is estimated at 500kt, seems to be standing up okay. But yes, that's an enormous test stand.

#### cvanc

##### Well-Known Member
Really interesting video; thanks for posting.

#### neil_w

##### Good at some things
TRF Supporter
Can you imagine the test stand needed to test the motor? 80 million pound of thrust would push the structural engineering of the stand to ridiculous levels.
I also liked some of the other numbers: 160db @5 miles away, 1 mile long plume. To which I can only say: :y:

#### Nytrunner

##### Pop lugs, not drugs
TRF Supporter
Burj Khalifa is estimated at 500kt, seems to be standing up okay. But yes, that's an enormous test stand.
We clearly need to install the motor upside down on it then. (still throws me off hearing khalifa cuz I watched a ton of documentaries/Modern Marvels that mentioned it when it was the burj Dubai)

Its still a massive rocket of ludicrous proportions. The mass flow alone to generate that thrust.......how in the world could they sustain that with a pressure fed system?

Similar questions about giant engines (Saturn V and larger) were asked back when I did a highschool program at JSC, and I've always remembered the guy's answer: Scaling things up doesn't linearly increase the difficulty, it cubes it.

#### GregGleason

##### Well-Known Member
I recall reading an article about BDB's in Time (or similar magazine) in the '80s or '90s. The part that struck me is that it would be built to "shipyard tolerances". Some of NASA's stuff is probably down to +/- 0.001" (or even tighter). I can't wrap my mind around things being 1/8" or so off, but the scale is so large it is mind-boggling. You can have a 100 foot length of steel "grow" in length by just sitting in the sun.

Greg

#### Nytrunner

##### Pop lugs, not drugs
TRF Supporter
1/8" tolerances? Yeah.......

I know engines like the Merlin and similar need tolerances in the 10,000ths of an inch for turbopumps and etc. Impeller too small, the efficiency drops significantly, too big and it makes friction with the housing. It isn't rocket science that's hard, its the rocket engineering.

#### jazzviper1

##### Well-Known Member
Most definitely, but supercomputers and CFD make each test run orders off magnitude more useful for redesign iterations.
I agree modern computers would be a big help, but this was proposed as competitor to the Saturn V. They would have tried to build this in the 1960s when such computers did not exist.
Though it may be possible I cant imagine it working on this scale even today.