Opps, I see where I missed the second stage of the Firefly having a "conventional" bell nozzle. Funny that I'd think they'd use aerospikes all around due to the bell size for orbital flight.Multiple engines exhausting into a single bell maybe? Or a whole new engine?Randy
For 2nd stage they use a bell nozzle optimized for vacuum. No need for aerospike as atmospheric pressure is constant ie vacuum.
The second stage has just one engine, so I don't think bell size is going to be much of a problem. And vacuum-optimized bell is probably more efficient than an aerospike for vacuum-only flight.
1. Is it possible to the heat propellants with pipework for the pressure feed just within the plug former itself?
3. It seem doubtful that second stage would have a 'plug' as this would increase total height, maybe a very short version as height same as nozzles?
4, Is it 'preesure-fed' or 'pressure-fed see firefly-b specs?
I'm not sure how "all pressure fed" translates into cost savings. Yeah, pumps are expensive to develop, but they're not the cost driver they used to be.
Aerospike enginesHistory tells us if companies or agencies invoke these, it is time to run.
I should interject a note of reality here:There is a list of technologies that are invoked when programs are in trouble, or if they are a long shot. Off the top of my head, there are a couple that come to mind, perhaps others can list more:Slush hydrogenAerospike enginesadded: Hydrogen peroxide oxidizerHistory tells us if companies or agencies invoke these, it is time to run.
Quote from: Danderman on 09/12/2014 03:06 pmI should interject a note of reality here:There is a list of technologies that are invoked when programs are in trouble, or if they are a long shot. Off the top of my head, there are a couple that come to mind, perhaps others can list more:Slush hydrogenAerospike enginesadded: Hydrogen peroxide oxidizerHistory tells us if companies or agencies invoke these, it is time to run.Why are you putting the mocker on hydrogen peroxide or HTP?
Great profile of Markusic on spacenews: http://spacenews.com/article/features/42177profile-thomas-markusic-founder-and-chief-executive-firefly-space-systemsgoes into his personal motivations, and some new information about their game plan and future aspirations. I'm sure some of the more knowledgeable folk here can glean more out of this than I can.
Alpha is just the simplest rocket we can build the soonest to establish that we can go to space. Next will be Beta, which we want to service the whole small-satellite range, up to a metric ton. Beta would use the same technologies as Alpha, except it’s parallel-staged. Beta looks like a Falcon Heavy Jr. or a Delta Heavy Jr., with three cores from Alpha. Next is Gamma, which is basically a Beta vehicle with side boosters that can be recovered. How they’re recovered I’m not sure yet. The boosters could be recovered with wings — a glide-back — or parachutes. Ultimately where we’d like to go is to have a reusable flyback stage, and that is our Delta vehicle, which looks more like a rocketplane — a rocketplane augmented with airbreathing propulsion that can do these sub-million-dollar smallsat launches. Delta might also be a platform to do point-to-point passenger travel. But that’s an aspirational thing right now; it’s something we don’t work on at all.
In particular, I thought that the small-satelllite market was being underserved and not properly addressed, and I feel strongly that it is an area that would help with the movement.
More coverage from Ars Technica: http://arstechnica.com/science/2014/11/firefly-space-systems-charges-full-speed-toward-low-earth-orbit/1/Author (self admittedly) doesn't know much about space, so it's full of inaccuracies and misunderstandings. Still an interesting read