An engineer’s take on Elon Musk’s proposal to make Falcon 9 reusable
Clark Lindsey asked an engineer experienced in building reusable spaceships for his take on Elon Musk’s proposal to make Falcon 9 reusable. The answer is fascinating.
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Clark Lindsey asked an engineer experienced in building reusable spaceships for his take on Elon Musk’s proposal to make Falcon 9 reusable. The answer is fascinating.
Readers!
Please consider supporting my work here at Behind the Black. Your support allows me the freedom and ability to analyze objectively the ongoing renaissance in space, as well as the cultural changes -- for good or ill -- that are happening across America. Fourteen years ago I wrote that SLS and Orion were a bad ideas, a waste of money, would be years behind schedule, and better replaced by commercial private enterprise. Only now does it appear that Washington might finally recognize this reality.
In 2020 when the world panicked over COVID I wrote that the panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
You can support me either by giving a one-time contribution or a regular subscription. There are four ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.
3. A Paypal Donation or subscription:
4. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652
You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above.
Yeah I was about it to.
SpaceX has kind of been all over the map with theFalcon-9. They started with the idea they were going to reuse Falcon-9s – but a ICBM style boosters about the worst place to start if you want a RLV. Originally they were going to parachute the stages into the ocean and fish them out for reuse –guess they figured that would likely beat the crap out of them – then corrode them. [The SRBs get trashed by water impact – you pretty much just reuse the steel cylinders.]
As for this Idea. Its kinda of like the Kistler, but it parachuted to the ground and landed on inflatable bags, last I remember?
As to things that worry me about the new Falcon design?
– Generally folks looking at designs like this have said the power to boost the first stage to a stop, and then boost back to the pad, and rocket VTOL land – eat up a lot of fuel. That could really cut you’re lift capacity. One way to get around the issue for the first stage is have it only boost straight up, stage directly over the base, and land straight down (like in “The Rocket Company” http://www.amazon.com/Rocket-Company-Library-Flight/dp/1563476967/ref=sr_1_1?ie=UTF8&qid=1317567871&sr=8-1 good book by the way) – but then the second stage needs to do all the horizontal velocity
– 2nd stage has similar issues -plus will you come down in the right distence? I mean by that a full orbit – AND you need to boost the empty stage sideways to compensate for the earths rotation under the trajectory (unless you stick to one exact traj that lines up with where the landing site will be.) so its also power consuming.
– 3rd, reentering a cylindar??!! Balancing it on a nose shield and keeping the stages long thin cylindar? Also the weight of the stage and fuel on that small shield could get pretty heavy per square foot of shield surface. [A flat side would let you skip off the atmosphere and steer.] This is why capsules tend to be short and wide – not long and thin; and ICBM warheads and DC-X designs, aerodynamic cones..
– 4th – a nit – how do you get the fuel & LOx to always “fall” toward the intakes in these manuvers.
I haven’t run the numbers for this stuff (hell I just relocated to a new place for a new contract), but off the top of my head these are some of my concerns. Again it looks like a amateurish and complicated kluge, to try to make a ICBM booster (designed for high performance and single use) be a RLV. If he just repackaged the engines and system in a non-ICBM config (Biamese, starclipper, DC-X, etc) he’ld save himself a ton of work and cost!
Kelly