Introducing Firefly Space Systems

[meekGee]

Well FWIW, when the number of peripheral nozzles decreases, so does the size of the plug.

[zaitcev]

Firefly-B photos. note the x4 nozzles on outer boosters

I can virtually guarantee you that the links between stages aren't going to stick to tank bodies like pictured. In fact, they are likely to come to extend or shrink the boosters a bit so that upper links connect to interstage or intertank (Chinese plan such stubby liquid boosters, for example). Alternatively, they can create a kind of a craddle like on H-IIA. But it's not going to look like pictured.

I'll say even more. In traditional metal rockets that fly enough to pay for themselves, it would make even more sense to put 4 engines on the center and 8 engines on boosters, and use equal diameters. Something a kindergartener would know to do. However, Firefly's production of composite tanks may be revolutionary enough, and flight rate may be low enough, for them to get away with something resembling the computer graphic that they posted. Or maybe they just asked an intern to draw without regard to reality.

[Silversheep2011]

 Firefly's production of composite tanks may be revolutionary enough,

I agree, and was thinking that these tanks might need something more exotic than the 'normal' garden variety carbon-fiber build up. (Fire resistance to Lox for instance)

You know having some more detail release from Firefly would be nice.
 We will be happy to do the rest of the discussion...!
 
Compare Here:   http://xcor.com/composites/

[simonbp]

Firefly-B photos. note the x4 nozzles on outer boosters

I can virtually guarantee you that the links between stages aren't going to stick to tank bodies like pictured. In fact, they are likely to come to extend or shrink the boosters a bit so that upper links connect to interstage or intertank (Chinese plan such stubby liquid boosters, for example). Alternatively, they can create a kind of a craddle like on H-IIA. But it's not going to look like pictured.

I'll say even more. In traditional metal rockets that fly enough to pay for themselves, it would make even more sense to put 4 engines on the center and 8 engines on boosters, and use equal diameters. Something a kindergartener would know to do. However, Firefly's production of composite tanks may be revolutionary enough, and flight rate may be low enough, for them to get away with something resembling the computer graphic that they posted. Or maybe they just asked an intern to draw without regard to reality.

You might be right, but I would be careful applying too much metal-tank intuition to composite tanks. Some structures which are really strong as metal are weak as composites, and vice versa.

[Llian Rhydderch]

Also, rather take somebody whose actual work made it into orbit (or at least flight)  than somebody who has flailed around working at multiple nuspace companies.

You should take your entrepreneurial ideas, and your hiring preferences, and start a company.  I hear there are a lot of folks with resumes out.

Take the risk.   

[TrevorMonty]

 Another article on Firefly, the following quote from this article was of interest.

http://motherboard.vice.com/read/the-rise-of-boutique-rocket-firms-inspired-by-spacex?trk_source=homepage-lede

The Firefly family of rockets will also use aerospikes instead of bell nozzles, and the company eventually plans to substitute kerosene for methane gas. “That really hasn’t been done in the world of rockets that lift payloads,” Blum told me.

Sounds like the first engines will be RP1 which makes sense from a business point of view. Developing Methane engines could delay LV by months if not years. Sooner the Firefly launches the sooner it is making money.

[Proponent]

I've got to say there are some problems with that article.  It suggests that Firefly's use of the same engines in the first and second stages is unique, when, in fact, Falcon 9 does the same thing.  The phrase "substitute kerosene for methane gas" indicates that Firefly will initially burn gaseous methane but will later switch to kerosene.

[ChrisWilson68]

The phrase "substitute kerosene for methane gas" indicates that Firefly will initially burn gaseous methane but will later switch to kerosene.

Yeah, I read it that way too at first, but it's clear from the context it means the opposite.  And I do remember occasionally hearing people say "substitute X for Y" to mean Y is replacing X.  It's the less-common ordering by far, but it's not unheard of.

[Silversheep2011]

Here is a good interview helps answer some of those basic questions:
aero spike engines, composite tanks, Alpha and Beta weight ranges



Watch it from13:10 onwards.

[Silversheep2011]

And this article from today:

Interestingly talks about pintle injectors use.
 and "heat exchanger for autogenous pressurization."
 so we finally figure out/confirm what function that grating in lower aero spike plug is doing....

http://aviationweek.com/space/spacex-alum-goes-after-falcon-1-market-firefly

[RanulfC]

Can't wait, (Ok I don't of course have a CHOICE actually ) for some testing on the engine.

Any ideas how tall the vehicle is? Looks, and due to the methane I'd kind of assume it's going to be taller than the Falcon-1 as its diameter is the same. (6ft)

I wonder if they can make it robust enough for possible air-launch

Randy

[TrevorMonty]

They have a lot of work ahead of them.
1) develop a new engine based on radical design.
2) develop autogenous pressurization system.
3) composite fuselage and tanks.
4) avionics
5) launch faculties
6) test faculties.
7) production faculties.

[QuantumG]

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.

[Proponent]

And this article from today:

Interestingly talks about pintle injectors use.
 and "heat exchanger for autogenous pressurization."
 so we finally figure out/confirm what function that grating in lower aero spike plug is doing....

http://aviationweek.com/space/spacex-alum-goes-after-falcon-1-market-firefly

How, then, is the upper stage, which lacks a plug, pressurized?  Or does it run at much lower pressure?

EDIT:  It occurs to me that my question is a bit silly.  To extract heat for pressurization of the upper stage's propellants, one could just regeneratively cool some portion of the nozzle extension.  That would be essentially the same thing as the grating on the plug, just inside out.  And a plug nozzle is, after all, pretty much an inside-out de Laval nozzle.

[Silversheep2011]

And this article from today:

Interestingly talks about pintle injectors use.
 and "heat exchanger for autogenous pressurization."
 so we finally figure out/confirm what function that grating in lower aero spike plug is doing....

http://aviationweek.com/space/spacex-alum-goes-after-falcon-1-market-firefly

How, then, is the upper stage, which lacks a plug, pressurized?  Or does it run at much lower pressure?

Good question?

Too get people thinking some more ....  [*** warning speculation ***]
Might it look something like the two outer boosters on Firefly-b configuration?

Notice in the attached image with 4 nozzles these appear to be 5' diameter and center 6' diameter.
copied from firefly website

Some related questions though,

1. Is it possible to the heat propellants with pipework  for the pressure feed just within the plug former itself?
2. If not.... is the pressure from cross-fed from the center core?
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? 

[RanulfC]

They have a lot of work ahead of them.

Granted, however the work might not be so difficult as its made out to be...

1) develop a new engine based on radical design.

They are actually developing a simpler and more well known version of the "plug-nozzle" called a mutli-chamber-plug-nozzle engine which has undergone decades of extensive non-flight testing.

2) develop autogenous pressurization system.

The same is true with the "self-pressurizing" rocket systems of which VPAC is one flown example and has a history of extensive ground testing.

3) composite fuselage and tanks.

Probably the simplist work as the techniques, manufacturing, and use of composites for all these purposes is already pretty standard even for rockets.

4) avionics

Space/launch qualified equipment might be a price driver here but its not like its not avaiable commercially

5) launch faculties

Depending on the "parting-terms" they could be looking at using the F1 facilities at Vandenburg or Kwaj... It might be something will be available at the Cape or Canaveral?

6) test faculties.

Those are probably avaible more now than in previous decades...

7) production faculties.

There's a lot of places that are and have been looking to attract such business... I kind of wish they would come to Utah

Randy

[FuseUpHereAlone]

Firefly-B photos. note the x4 nozzles on outer boosters

Interesting to see that the boosters only have 4 nozzles.  I would think they'd have more in order to generate more thrust than the core at lift-off and burn-out sooner.

[RanulfC]

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.

The idea that pressure fed is lower cost due to avoiding turbo-pumps is one that came from all the "Big Dumb Booster" studies and other "Lowest Cost" launch studies. I've never really thought the actual argument was all that supportable. Especially given the the most under-rated, robust and reusable rocket engine ever made was driven by a mechanical turbopump designed in the 1950s
http://en.wikipedia.org/wiki/H-1_(rocket_engine)
http://ota.fas.org/reports/8904.pdf

Moreso though because both turbopump costs and alternatives (such as the piston pump) have come along over the years.

Though I suspect a lot of it is having to "outsource" parts as little as possible. Given the size of the multiple rockets on the vehicle normal "turbo-pumps" would proably be heavier and much more complex and expensive than going with self-pressurization though I'd have thought it would have been ready-made for piston-pumps that too might be more expensive due to having to out-source them.

How, then, is the upper stage, which lacks a plug, pressurized?  Or does it run at much lower pressure?

Good question?

Where does this idea come from? Both stages use the "Lumen" engines the first stage is listed as the FRE-2 while the upper uses the FRE-1 (http://www.fireflyspace.com/vehicles/firefly-a) and nothing I've seen/heard/found would lead me to assume they are not both plug-nozzles with the associated self-pressurization system...

Too get people thinking some more ....  [*** warning speculation ***]
Might it look something like the two outer boosters on Firefly-b configuration?

Notice in the attached image with 4 nozzles these appear to be 5' diameter and center 6' diameter.
copied from firefly website

You call THAT speculation? Hmmmph, amateur...

Seriously I'm already wondering about air-launch, alternate propellants and manned launches
(It was pointed out at one point and time that the Falcon-1 "could" put up a two or one person capsule about the size of the SS1...)

I suspect that's right though on the engine configuration because a 4-chamber plug nozzle would have less thrust than the "booster"  which seems to show 8-chambers. I think it was just using the upper stage aerospike illustration in place of the actual booster stages. (Unless the boosters cross-feed to the core and the engines only have to "lift" their own mass?)

Some related questions though,

1. Is it possible to the heat propellants with pipework  for the pressure feed just within the plug former itself?

I'd think we'd established the "grid" in the middle of the plug is the Heat-Exchanger system? Bonus question: If so and since they are looking at future reusable recovery could propellant be retained to run through the HX during reentry and then dumped over board from the nozzles? This has been seen as proposed for a large number of plug-nozzle engine/heat-sheild concepts.

2. If not.... is the pressure from cross-fed from the center core?

That's not possible I think from the way self-pressurization works:
http://www.holderaerospace.com/downloads/Technical_Papers/VaPak%20Systems%20Overview.pdf
http://enu.kz/repository/2009/AIAA-2009-5221.pdf
http://aa.stanford.edu/students/media/posters2014/zimmerman.pdf
http://pdf.aiaa.org/preview/CDReadyMJPC2005_1177/PV2005_3549.pdf

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?

No actually the "plug" would be shorter than a regular nozzle so its being used and for the same reason as they lower one. IE: a "normal" bell nozzle would have to be huge to compinsate for the lack of pressure, meanwhile the same plug nozzle works here as well as for the booster.

4, Is it 'preesure-fed' or 'pressure-fed   see firefly-b specs? 

Depends on how many beers its had before it takes off I suppose

Randy

[RanulfC]

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

[TrevorMonty]

For 2nd stage they use a bell nozzle optimized for vacuum. No need for aerospike as atmospheric pressure is constant ie vacuum.