Quote from: john smith 19 on 10/21/2020 06:08 amQuote from: Asteroza on 10/20/2020 11:30 pmI dunno, with the recent discussion on plastic engines, the bar may have been lowered for small engine development? Either way, the original Bricklifter/Mockingbird concept is the concept of record that nobody seems to be actively emulating, which always struck me as odd.Perhaps you should look at the original paper on the subject. hereThat's a long way from a "plastic" engine, but it suggests directions for research. Mockingbird was a reciprocating engine concept specifically because turbo pumps are difficult at this scale and they wanted to show better than pressure fed was possible at this scale, which they did.I meant plastic engines for an easier dev cycle allowing high physical iteration, not the final engine. Also, due to nomenclature, I feel I should point out for those reading that the rough 5000lbs rule of thumb for turbopumps vs something else (reciprocating, specifically Whitehead envisioning a third gas driving a piston pump) is specifically referring to the difficulty of manufacturing/designing the turbine driving the compressor pump (axial or centrifugal). Which is why when Rocketlabs substituted an electric motor for the turbine, they get most of the turbopump benefits.
Quote from: Asteroza on 10/20/2020 11:30 pmI dunno, with the recent discussion on plastic engines, the bar may have been lowered for small engine development? Either way, the original Bricklifter/Mockingbird concept is the concept of record that nobody seems to be actively emulating, which always struck me as odd.Perhaps you should look at the original paper on the subject. hereThat's a long way from a "plastic" engine, but it suggests directions for research. Mockingbird was a reciprocating engine concept specifically because turbo pumps are difficult at this scale and they wanted to show better than pressure fed was possible at this scale, which they did.
I dunno, with the recent discussion on plastic engines, the bar may have been lowered for small engine development? Either way, the original Bricklifter/Mockingbird concept is the concept of record that nobody seems to be actively emulating, which always struck me as odd.
I suspect the reason why Delta 7925 has a lower gravity loss is the higher initial acceleration from all those solids. Same with the Space Shuttle. Drag losses are mainly related to the mass to area ratio of the vehicle. A higher mass vehicle for the same area will have less drag losses, which I like to call the Titanic effect. The bigger your vehicle is, the less drag loss you will have, which is evident in the Saturn V.
Those who cannot learn from history are doomed to repeat it.
Jim Cantrell is back in small LV business with new company called Phantom. Must of found a Billionaire backer that wants to become Millionaire.https://twitter.com/jamesncantrell/status/1322399546350002177?s=09
Quote from: jstrotha0975 on 10/31/2020 08:02 pmThose who cannot learn from history are doomed to repeat it.So a man walked away from SpaceX because he thought it would never turn a profit is trying to emulate them.Again. His investors had better hope his decision making skills and ability to tell the difference between winners and losers has improved with bankruptcy I will wish them well.
Then, less than a year later, Cantrell quit suddenly. "Elon yelled at me one too many times," he says. "I was done. And frankly, I just wasn't interested in what he was doing at the time. I really didn't think he treated this as a commercial activity." (SpaceX did not return requests for comment on Cantrell's accounts of the company's early days.)
Quote(SpaceX did not return requests for comment on Cantrell's accounts of the company's early days.)
(SpaceX did not return requests for comment on Cantrell's accounts of the company's early days.)
I think the quote was that Elon yelled at him one too many times.QuoteThen, less than a year later, Cantrell quit suddenly. "Elon yelled at me one too many times," he says. "I was done. And frankly, I just wasn't interested in what he was doing at the time. I really didn't think he treated this as a commercial activity." (SpaceX did not return requests for comment on Cantrell's accounts of the company's early days.)https://www.inc.com/kevin-j-ryan/vector-building-rockets-jim-cantrell-spacex.html
I just wasn't interested in what he was doing at the time.
The Chinese is now 2-1 to everyone else in this world for small satellite start-up LSPs reaching orbit since the 2010s IIRC.... https://twitter.com/Cosmic_Penguin/status/1324981493807026176
The Gushenxing-1 is a 4 stage rocket, probably based on demilitarized solid motors from the DF-21 missile. Stage 1 and 2 are 1.4m in diameter, Stage 3 is 1.2m in dia. Stage 4 is a liquid orbit insertion stage.
China's government sells demilitarized large solid rocket motors to commercial startup companies, allowing those companies to develop satellite launch vehicles rapidly
So I don't see this in anyway comparable to the rest of the world where smallsat launchers are liquid fueled and developed from scratch.
Quote from: su27k on 11/07/2020 03:23 pmSo I don't see this in anyway comparable to the rest of the world where smallsat launchers are liquid fueled and developed from scratch.Indeed. What exactly is the "development" work they are doing here?
