Author Topic: Introducing Firefly Space Systems  (Read 340730 times)

Offline Silversheep2011

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Re: Introducing Firefly Space Systems
« Reply #160 on: 07/11/2014 03:05 am »
Could please help with the acronym, TVC I goggled it, and I know it doesn't mean 'Television Commercial' :o

Offline QuantumG

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Re: Introducing Firefly Space Systems
« Reply #161 on: 07/11/2014 03:15 am »
Thrust vector control.
Human spaceflight is basically just LARPing now.

Offline Silversheep2011

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Re: Introducing Firefly Space Systems
« Reply #162 on: 07/11/2014 03:27 am »
Thanks QuantumG, - pretty obvious when you start to think about it.-

Have a look at this picture perhaps this is  'Thrust Vectoring Control' going on the outer X8 engine cores? Or is more related to improving efficiencies going on as it climbs through the atmosphere?
« Last Edit: 07/11/2014 03:30 am by Silversheep2011 »

Offline HMXHMX

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Re: Introducing Firefly Space Systems
« Reply #163 on: 07/11/2014 04:10 am »
Thanks QuantumG, - pretty obvious when you start to think about it.-

Have a look at this picture perhaps this is  'Thrust Vectoring Control' going on the outer X8 engine cores? Or is more related to improving efficiencies going on as it climbs through the atmosphere?

Some early plugs designs proposed individual chamber radial tilt (like the image) for TVC.  But to my knowledge no one has ever fired even a static test version of that approach.  It will be interesting to see how well it works and how it disrupts the exhaust attachment to the plug surface at both sea level and altitude conditions.

Offline Silversheep2011

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Re: Introducing Firefly Space Systems
« Reply #164 on: 07/11/2014 06:27 am »
Just found this video: Something for us visiting this thread to compare and contrast with
http://www.hybrids.com/video/aerospike.mpg

The test is static and sea level exhaust plume takes on that interesting coke cola bottle profile. 
« Last Edit: 07/11/2014 06:28 am by Silversheep2011 »

Offline john smith 19

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Re: Introducing Firefly Space Systems
« Reply #165 on: 07/11/2014 09:31 pm »
Some early plugs designs proposed individual chamber radial tilt (like the image) for TVC.  But to my knowledge no one has ever fired even a static test version of that approach.  It will be interesting to see how well it works and how it disrupts the exhaust attachment to the plug surface at both sea level and altitude conditions.
So with the carbon fiber tankage and the plug nozzle engine this is yet another additional complication to a TSTO.  :(

OTOH relatively simple large composite structures have been around for some time.

A report in cryogenic materials described an LNG tank 6m in diameter at 900psi with an Aluminum reinforced glass fibre structure in 1982. The point is mfg techniques to do that have been around for 30 years.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline TrevorMonty

Re: Introducing Firefly Space Systems
« Reply #166 on: 07/11/2014 10:02 pm »
I see development of the aerospike engine being the most risky part of this design. I don't doubt they can do it but it may take a lot longer than expected.

If the aerospike engine meets performance expectations, it should be a gamechanger.

Offline ChrisWilson68

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Re: Introducing Firefly Space Systems
« Reply #167 on: 07/11/2014 10:08 pm »
I see development of the aerospike engine being the most risky part of this design. I don't doubt they can do it but it may take a lot longer than expected.

If the aerospike engine meets performance expectations, it should be a gamechanger.

How is the aerospike a game changer?  At best, it only gives moderately better overall performance.  People have known how to make aerospike engines for a long time but by and large there hasn't been much interest in them.  If it were going to be a game changer, every launch vehicle would already be using aerospikes.

Offline M_Puckett

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Re: Introducing Firefly Space Systems
« Reply #168 on: 07/11/2014 10:37 pm »
Aerospikes only make sense as a sustainer engine that fires from surface to near-orbit or a situation where you are size constrained on the nozzle.

Offline Silversheep2011

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Re: Introducing Firefly Space Systems
« Reply #169 on: 07/11/2014 11:10 pm »
How is the Aerospike a game changer?" Maybe it’s not. And never will be.

Having said that it’s not uncommon for technology to take many years to filter through to main stream production

I take my Holden (G.M.) V6 3.8 L car from 1987 as an example and compare it back in the 60’s & 70's when Carburetors and breaker points where the standard configuration - Remember those years going out late at night and putting a .012" feeler gauge in between the points while balancing  a meat pie in the other hand! Or how painful cleaning the carburetor bowl out. and dropping a jet on the floor and replacing the gaskets.
I'm really glad they are behind us now and replaced with Electronic ignition and Fuel injection. My poor old girl has 297,000 km's (185,000 miles) on the clock yet see goes fine. In part due to these technologies being added.

 So yes, the march of time bring changes.

 I don't think saying "If it were going to be a game changer, every launch vehicle would already be using aerospikes"   is good reasoning.

How many times do we see developments that offers a 10% maybe 20% efficiency improvements and it takes (many) years, or decades for it to become common place?

-Myself, I like doing the compare /contrast thing.-

What are the relative merits of this technology?
Why does Tom Merkusic, do what he does, and for what reason?
What’s novel and different about this ‘firefly’ compared to other rocket design's?
What possible design flaws, and problems may they  encounter on the way? And the alike.

That’s the fun part of these threads. How do thing's work?
How do we contribute to the development of space flight?
Maybe one day we just happen to say something, or point out just the right thing.
That changes human history forever!
« Last Edit: 07/11/2014 11:43 pm by Silversheep2011 »

Offline Davidthefat

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Re: Introducing Firefly Space Systems
« Reply #170 on: 07/12/2014 01:01 am »
Follow up question: what do these 3 components represent on the truncated Aero spike center.
1. looks like a cylindrical center piece, function unknown?
2. looks like a heating transfer grid of come sort? - or is a flame arrest?
3. looks like an internal nozzle, again function unknown?

In a truncated aerospike, there's a low pressure zone where the the spike is truncated. It makes the hot gases recirculate in that zone and makes the engine lose some thrust. That center piece looks like it's for some kind of gas to flow out of to create a slightly high pressure to prevent that gas re-circulation.


The only paper I've seen on thrust differential on an annular aerospike uses throttling of the nozzles, not gimbals.
« Last Edit: 07/12/2014 01:03 am by Davidthefat »

Offline Burninate

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Re: Introducing Firefly Space Systems
« Reply #171 on: 07/12/2014 01:02 am »
An aerospike rocket engine efficiently modifies the expansion ratio of the exhaust to one appropriate for the air pressure.

This is not an aerospike rocket engine.

This is an air augmented rocket with ramjet/scramjet characteristics and a truncated aerospike which may or may not be a bypass nozzle, which has novel separated conventional bell nozzles for individual combustion chambers exterior to this assembly...

or something.
« Last Edit: 07/12/2014 01:02 am by Burninate »

Offline Prober

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Re: Introducing Firefly Space Systems
« Reply #172 on: 07/12/2014 02:26 am »
An aerospike rocket engine efficiently modifies the expansion ratio of the exhaust to one appropriate for the air pressure.

This is not an aerospike rocket engine.

This is an air augmented rocket with ramjet/scramjet characteristics and a truncated aerospike which may or may not be a bypass nozzle, which has novel separated conventional bell nozzles for individual combustion chambers exterior to this assembly...

or something.

care to explain the differences, would be very educational? ;)
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Offline Silversheep2011

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Re: Introducing Firefly Space Systems
« Reply #173 on: 07/12/2014 03:57 am »
Have a look at attachment:

1, I'm thinking its possibly part of the self pressurization system and a high pressure collector in the center to  return liquids in gas form back to the tanks.
2, It could be dual gas Lox and Methane fed piping.
3, Foresee see possible thermal cracking issues at weld junctions too sharp and not enough 'give' in them.

Note: Carbon fire is a wonder material for lightness. And we probably should have been doing more of this 'swap out and replace' years ago. Tanks in particular, due to the tremendous weight savings.
 Carbon fiber's  one downside is it tends to be brittle in failure mode.
And what I'm not too sure on the latest information on, is  predicating the  'Fatigue Life' cycle quality and how well that has been tested or modeled. I do know its a difficult subject.
Being more brittle in nature, fracture toughness could be challenging aspect meaning it will not tend to crumble up in a crash. But will fail by bursting or cracking open. Although I think the current design work around is simply increasing the mechanical safety strength margins to resolve the issue.
« Last Edit: 07/12/2014 04:21 am by Silversheep2011 »

Offline FuseUpHereAlone

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Re: Introducing Firefly Space Systems
« Reply #174 on: 07/12/2014 04:51 am »
To me this aerospike looks woefully underexpanded (if that's the right term of course for aerospikes  :P).  I mean just eyeballing the differences between the FireFly concept and XRS-2200 linear aerospike, you can see that the FireFly engine expands most of the gases in the "bell" portion of the nozzle while the XRS-2200 expands it on the spike itself. 

Offline go4mars

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Re: Introducing Firefly Space Systems
« Reply #175 on: 07/12/2014 05:41 am »
I brought this up in a SpaceX thread when everyone thought the middle bell hung lower than the others on what was subsequently revealed as the V1.1

But shouldn't Bernoulli force from the ring of little engines make the perceived pressure for the middle vacuum equivalent?  Hence, vacuum equivalent ISP for the truncated aerospike in the middle...from the moment it leaves the launch pad?  With pressure of the plumes from the outer engines acting as the large nozzle for the broad expansion of the middle plume.  Outer engine throttle variance and/or tilt angle to change the shape of the main plume ("fingerless vectoring nozzle")?

Also, would the RAM be more accurately called a RAM TAN?  What's the presumed flow path of the rammed air?  To keep "dead zones" moving barely subsonic?

« Last Edit: 07/12/2014 05:55 am by go4mars »
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Offline john smith 19

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Re: Introducing Firefly Space Systems
« Reply #176 on: 07/12/2014 07:16 am »
Follow up question: what do these 3 components represent on the truncated Aero spike center.
1. looks like a cylindrical center piece, function unknown?
2. looks like a heating transfer grid of come sort? - or is a flame arrest?
3. looks like an internal nozzle, again function unknown?

In a truncated aerospike, there's a low pressure zone where the the spike is truncated. It makes the hot gases recirculate in that zone and makes the engine lose some thrust. That center piece looks like it's for some kind of gas to flow out of to create a slightly high pressure to prevent that gas re-circulation.


The only paper I've seen on thrust differential on an annular aerospike uses throttling of the nozzles, not gimbals.
Interesting point. The two papers on plug nozzles that I know that were actually built were a GE pressure fed in the 50's and the one built by Rocketdyne in the 70's for the USAF AFRL under Dr Huang (that's the co-author of "Modern Engineering for the Design of Liquid Propellant Rocket Engines"

The former was a ground test engine where some of the chambers were 15% below nominal (IIRC the rest ran at normal pressure) to give a 5degree shift in the angle of the thrust.

The latter was the only known flight weight plug nozzle I've ever seen. It did use a gimbal mounting of the whole structure (the base plate was a key part of the design and was made of 2 layers of Ti plate machined into a waffle pattern perforated to evenly spread what I think was some of the expander exhaust. The whole engine hung from 4 upside down V shaped supports which in a vehicle would be the gimbals.

I'd quote a reference but I've just tried to used the ARC AIAA search function and it seems to have gone down the toilet (has AIAA sold it's collection to some private company?).  :(
« Last Edit: 07/12/2014 07:17 am by john smith 19 »
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline ChrisWilson68

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Re: Introducing Firefly Space Systems
« Reply #177 on: 07/12/2014 07:32 am »
I don't think saying "If it were going to be a game changer, every launch vehicle would already be using aerospikes"   is good reasoning.

How many times do we see developments that offers a 10% maybe 20% efficiency improvements and it takes (many) years, or decades for it to become common place?

I think you have a very different definition of the term "game changer" than I do.

To me, a game changer is something new that has such a huge impact that none of the players can continue doing what they were doing -- they must react or die, because the game has changed.

That's not to say that incremental improvements don't matter.  They do.  But they are part of the normal game.  They don't change the game.  Over time, there can be huge improvements in technology in a particular area without there ever having to be a game changer along the way.

What does the term "game changer" mean to you?

Offline ChrisWilson68

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Re: Introducing Firefly Space Systems
« Reply #178 on: 07/12/2014 07:41 am »
An aerospike rocket engine efficiently modifies the expansion ratio of the exhaust to one appropriate for the air pressure.

This is not an aerospike rocket engine.

This is an air augmented rocket with ramjet/scramjet characteristics and a truncated aerospike which may or may not be a bypass nozzle, which has novel separated conventional bell nozzles for individual combustion chambers exterior to this assembly...

or something.

The current Firefly web site says "Featuring an aerospike engine" when describing their first launch vehicle.  This is the same page the pictures we're all analyzing come from.  That page does not mention the terms "ramjet" or "scramjet".

Older information, with a much different graphic, from Firefly did mention an air-breathing engine, but those mentions have been dropped.

So, I'd have to say you're wrong to say it's not an aerospike and wrong to say it's a ramjet or scramjet, based on the best currently-available information.

Offline Silversheep2011

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Re: Introducing Firefly Space Systems
« Reply #179 on: 07/12/2014 09:17 am »
I don't think saying "If it were going to be a game changer, every launch vehicle would already be using aerospikes"   is good reasoning.

How many times do we see developments that offers a 10% maybe 20% efficiency improvements and it takes (many) years, or decades for it to become common place?

I think you have a very different definition of the term "game changer" than I do.

To me, a game changer is something new that has such a huge impact that none of the players can continue doing what they were doing -- they must react or die, because the game has changed.

That's not to say that incremental improvements don't matter.  They do.  But they are part of the normal game.  They don't change the game.  Over time, there can be huge improvements in technology in a particular area without there ever having to be a game changer along the way.

What does the term "game changer" mean to you?

I think I understand where you are coming from, to me little to moderate things can also be game changes:
like:
* fuel injection on cars  [ already motioned ]
* Iphone
* window 8 [I hate it]
* 52" Flat screen TV and Dolby sound
*Trucks fitted out with aerodynamic devise to improve fuel efficiencies

Pretty much because they influence peoples lives and the way we live.
Possible game change's I have my eye on  for the future are:

* Graphene
* Al- Air batteries or Li-Si versions working in with solar power
* Windows 9
*3d printing ( we have one at work)

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