The WaPo has a nice survey of all the passenger vehicles coming down the pike (so to speak). I’d note that it’s not just the Lynx Mark II that may not be built, it’s the Lynx Mark I as well.
3 thoughts on “The New Space Race”
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The WaPo has a nice survey of all the passenger vehicles coming down the pike (so to speak). I’d note that it’s not just the Lynx Mark II that may not be built, it’s the Lynx Mark I as well.
Comments are closed.
I would still like an explanation for why SpaceX doesn’t use parachutes to slow down the first stage prior to landing. Once the rocket goes subsonic, ‘chutes can be deployed to shed several hundred KPH, like the solid rocket boosters of yore. Would they actually cost more propellant on the way up than they would save on the way down?
My understanding is that SpaceX actually tried parachutes a time or two and they didn’t work. Apart from that I can think of several reasons not to go that route:
1) Chutes capable of useful slowdown on an F9 1st stage are big and heavy. That mass is entirely parasitic on the way up and limits the extra fuel load that could be used for a propulsive landing.
2) With the F9 1st stage already pushing the fineness ratio envelope pretty hard, space for chutes could only come at the expense of tankage volume.
3) 1st stages are engineered to be pushed hard from the bottom, not given sudden hard jerks from above. The extra structure beef and/or shock absorber mechanics needed to mitigate parachute opening shock loads is, again, purely parasitic.
4) A parachute makes precision landings – e.g., on the ASDS’s – effectively impossible unless one cuts it loose at a significant altitude. If you do that, you either have to eat the cost of a chute for each mission or retrieve the thing somehow. You also lose some of the benefit of using a chute in the first place as the stage will accelerate again as soon as it cuts the chute loose.
The SpaceX engineers are obviously no dummies. Parachutes are traditional in re-entry/recovery, but I think we can safely assume that SpaceX trade studied this whole issue pretty much to death and arrived at the conclusion that some traditions are not worth observing. Doubtless the SpaceX engineering staff could give you a “Why Not Chutes?” list many times as long as mine.
Once the first stage is done boosting, you have rocket engines that you KNOW work. They just have to survive being re-lit.
You wouldn’t have the same confidence in a parachute, since every deployment is essentially the first time.