Flometrics has ambitious rocket plans

[DiggyCoxwell]

   Check this youtube footage out:



  There's more where that came from.

The San Diego based Flometrics company
has ambitious plans and a remarkable string of success
what with an 800 Ibf thrust rocket using diesel biofuel
that went upto Mach 0.93 among other achievements
It's the first rocket that I know to use biofuel.

On September/20/2002 they sent a rocket upto 20,000 foot altitude.
Pretty good considering many X-Prize competitors never achieved
even these benchmarks for rocketry.

Flometrics has also launched a rocket with a motor generating 1,000Ibf
thrust.
They are working on a rocket, SDSU, that will achieve an altitude
over 100 miles up.
If the Flometrics rocket team and company are 'amateurs', they're not shy about their successes and plans.
 

[William Barton]

I don't suppose anyone would consider that the V-2 used biofuel (ethyl alcohol)...

[TyMoore]

These are the folks that use a novel pneumatic pumping system using pressurized gas in a set of 4 small run tanks. As one tank is pneumatically filled at low pressure from the main tank, the other uses pneumatic pressure to pump the propellant into to the rocket engine at higher pressure. By sequencing valves to alternate the fill/expell cycles you get a pump. One pump for each propellent: 4 run tanks total. It gives the advantage of the simplicity of a piston pump, the power of a higher performance turbopump (to a limited extend) and the lightness of the main tanks because they aren't pressurized to the full injector pressure pluss pressure drop.

It reminds me of an idea that I had when I was a kid, but I never did anything with it. And they've got the patents.

These folks are going places!

[HMXHMX]

These are the folks that use a novel pneumatic pumping system using pressurized gas in a set of 4 small run tanks. As one tank is pneumatically filled at low pressure from the main tank, the other uses pneumatic pressure to pump the propellant into to the rocket engine at higher pressure. By sequencing valves to alternate the fill/expell cycles you get a pump. One pump for each propellent: 4 run tanks total. It gives the advantage of the simplicity of a piston pump, the power of a higher performance turbopump (to a limited extend) and the lightness of the main tanks because they aren't pressurized to the full injector pressure pluss pressure drop.

It reminds me of an idea that I had when I was a kid, but I never did anything with it. And they've got the patents.

These folks are going places!

I first saw the basic concept of displacement pumps of this type in 1960, in Felix Goodwin's "Exploration of the Solar System" but his idea used a membrane.  A number of others, including John Whitehead at LLNL, have built and tested piston pumps, and John even flew one about fifteen years ago. Steve has added to the technology base by demonstrated pumping without a membrane or pistons.

[kkattula]

These are the folks that use a novel pneumatic pumping system using pressurized gas in a set of 4 small run tanks. As one tank is pneumatically filled at low pressure from the main tank, the other uses pneumatic pressure to pump the propellant into to the rocket engine at higher pressure. By sequencing valves to alternate the fill/expell cycles you get a pump. One pump for each propellent: 4 run tanks total. It gives the advantage of the simplicity of a piston pump, the power of a higher performance turbopump (to a limited extend) and the lightness of the main tanks because they aren't pressurized to the full injector pressure pluss pressure drop.

It reminds me of an idea that I had when I was a kid, but I never did anything with it. And they've got the patents.

These folks are going places!

I first saw the basic concept of displacement pumps of this type in 1960, in Felix Goodwin's "Exploration of the Solar System" but his idea used a membrane.  A number of others, including John Whitehead at LLNL, have built and tested piston pumps, and John even flew one about fifteen years ago. Steve has added to the technology base by demonstrated pumping without a membrane or pistons.

It appears to be a remarkably simple yet effective technology. (Although the devil is probably in the details).  IIRC, a few years ago Armadillo built some working test pumps, with and without free pistons, over a weekend.

One interesting technique is to use heat from the rocket engine to heat up the pump pressurant gas. This can substantially decrease the mass of pressurant, and/or mass of the pressurant tank.

Another idea is to use a gas generator to produce the pressurant gas in flight.

Both these have parallels to existing turbo-pump cycles. Which is to be expected since a turbo-pump is just a different approach to the same task of using high pressure gas to push propellants into a combustion chamber at high pressure.

[jongoff]

These are the folks that use a novel pneumatic pumping system using pressurized gas in a set of 4 small run tanks. As one tank is pneumatically filled at low pressure from the main tank, the other uses pneumatic pressure to pump the propellant into to the rocket engine at higher pressure. By sequencing valves to alternate the fill/expell cycles you get a pump. One pump for each propellent: 4 run tanks total. It gives the advantage of the simplicity of a piston pump, the power of a higher performance turbopump (to a limited extend) and the lightness of the main tanks because they aren't pressurized to the full injector pressure pluss pressure drop.

It reminds me of an idea that I had when I was a kid, but I never did anything with it. And they've got the patents.

These folks are going places!

I first saw the basic concept of displacement pumps of this type in 1960, in Felix Goodwin's "Exploration of the Solar System" but his idea used a membrane.  A number of others, including John Whitehead at LLNL, have built and tested piston pumps, and John even flew one about fifteen years ago. Steve has added to the technology base by demonstrated pumping without a membrane or pistons.

It appears to be a remarkably simple yet effective technology. (Although the devil is probably in the details).  IIRC, a few years ago Armadillo built some working test pumps, with and without free pistons, over a weekend.

One interesting technique is to use heat from the rocket engine to heat up the pump pressurant gas. This can substantially decrease the mass of pressurant, and/or mass of the pressurant tank.

Another idea is to use a gas generator to produce the pressurant gas in flight.

Both these have parallels to existing turbo-pump cycles. Which is to be expected since a turbo-pump is just a different approach to the same task of using high pressure gas to push propellants into a combustion chamber at high pressure.

Yeah, the Armadillo experiments were based on hearing about Steve's work.  IIRC, Steve's done a lot of work on getting the pulses damped out enough that it doesn't end up causing instabilities.  Flometrics actually built a workhorse pump for us for a now totally deprecated LV that we were working on a few years back.  We didn't have enough money at the time to actually take it all the way through flight demonstration, but they did a bunch of LN2 pumping tests for us at the time.  Hopefully one of these days we'll be to the point where we can have him finish up a pump for us.

~Jon

[kkattula]

It would be very interesting if a company like Blue Origin actually ponied up the money to build a large scale pump set.

A few years ago, I did a rough design and simulation of a sub-orbital (100km), lox/methanol vehicle using pistonless pumps. Pump pressurant gas (He) was about 1.1% of GLOW, of which half was used to maintain propellant tank pressure and do RCS, the rest exhausted overboard. Propellant tank masses were quite low.

Another excellent feature of pistonless pumps, is that you can leave one chamber of each pump filled at shutdown. This allows zero-g restarts without settling the tanks.

[Downix]

I've at times pondered a piston-driven pressure tank fed system.

[kevin-rf]

Another excellent feature of pistonless pumps, is that you can leave one chamber of each pump filled at shutdown. This allows zero-g restarts without settling the tanks.

Using cryo-fuels how would you handle boil off? I guess you could bury the pump inside the tank...

[jongoff]

A few years ago, I did a rough design and simulation of a sub-orbital (100km), lox/methanol vehicle using pistonless pumps. Pump pressurant gas (He) was about 1.1% of GLOW, of which half was used to maintain propellant tank pressure and do RCS, the rest exhausted overboard. Propellant tank masses were quite low.

One problem with this is that while 1.1% of GLOW sounds like very little, Helium is extremely low density.  Xoie had a GLOW without payload of about ~820lb, with 6lb of that being helium.  But the helium tanks, regulators, etc ended up weighing almost as much as the propellant tanks did.  You can make a pistonless pump work with regulated helium and no other gimmicks, but it doesn't end up saving you as much mass for the added complexity.  Steve's had several interesting ideas though over the years, ranging from using Tridyne helium, using helium to boost a small amount of propellant up to high enough pressure to vaporize it and then use it as the pumping fluid, or using a supercritical helium tank (at LHe temps) running on blowdown and using heat exchangers, etc.

Some of the more sophisticated systems could get you up into a similar performance range to gas generator turbopumps.  I'm kind of a fan of the Tridyne approach though--relatively simple, and it still cuts your helium needs by a factor of 3-4 depending on details. 

That said, for 100km you really don't need pumps, so we haven't messed with them yet.

~Jon

[jongoff]

Another excellent feature of pistonless pumps, is that you can leave one chamber of each pump filled at shutdown. This allows zero-g restarts without settling the tanks.

Using cryo-fuels how would you handle boil off? I guess you could bury the pump inside the tank...

Yeah, Steve's pumps were always planned on running inside the tank.  It cuts down on how much propellant you need to condition the pump.  If you pressurize the ullage a little bit on the pump tank, it's boiling point increases a bit, so the liquid will be subcooled compared to the rest of the propellants.  So long as you can keep the pump in good thermal contact with the remaining propellant, it should suppress boiloff.  The problem is, if you could keep the pump always submerged, that assumes some sort of liquid acquisition already.

~Jon

[DiggyCoxwell]

   Flometrics successfully tested a different rocket that
used zinc and sulfur for propellant.
It did pretty well.
I'd be interested to know what the specific impulse
for zinc-sulfur propellant is (Isp in a vacuum, and Isp for sea level for instance)
I haven't found a website that gives that info.

[TyMoore]

Zinc sulfur is fun--I've made a couple of small rocket engines with that, nothing very big (reloaded several spent B-class model rocket motors.) You'll get Isp just a shade better than black powder, maybe 80 seconds or so.

As a kid, I always wanted to experiment with composite propellants (AP-AL-PBAN.)

Pistonless pumps are pretty cool--does anyone know what the crossover threshold would be between turbopumps and pistonless pumps? I'd WAG maybe 10 lbs/s flow rate at 1000 psia...

[jongoff]

Pistonless pumps are pretty cool--does anyone know what the crossover threshold would be between turbopumps and pistonless pumps? I'd WAG maybe 10 lbs/s flow rate at 1000 psia...

Actually pistonless pumps scale up pretty well (they're just pressures vessels and valves for the most part).  Some of the concepts Steve has researched look like they could actually be a bit better performance than gas generator turbopumps, but the development cost should be substantially lower.

~Jon

[Danderman]

Whatever happened to these guys?

 

Any idea of the performance of their rocket engine in terms of ISP?

[tdperk]

I searched the forums for Flometrics and am also wondering, what has gone on with the concept?

Seems like the only "low hanging fruit" SpaceX (or their competitors) could pick which would substantially reduce their hardware cost.

[Nomadd]

Whatever happened to these guys?

 

Any idea of the performance of their rocket engine in terms of ISP?

http://www.flometrics.com/wp-content/uploads/2014/09/RocketPumpSpace2004.pdf
 That's mostly about their pump, but has some engine figures for various fuels.
 I see an article where someone from Flometrics remarked that the biodiesel ISP was about 4% less than RP-1.
http://aviationweek.com/awin/biodiesel-touted-renewable-rocket-fuel
 Most of the article is hidden behind a wall.

[Steven Pietrobon]

Here's a web archive of their early launches. Also has photos of that zinc/sulfur launch.

https://web.archive.org/web/20030606221555/http://flometrics.com/rockets.html

V1  3 Dec 2000 Engine blew up on ignition
V2    Jan 2001 Parachute failed to deploy
V3  3 Jun 2002 Lost in Desert
V4 20 Sep 2002 Parachute failed
   11 Jul 2009 Biofuel Flight Test

[tdperk]

I am at a loss as to why a propellant pressurization system so much less expensive than turbopumps and with equivalent performance and likely better reliability has not seen commercial development.

Any speculation?

[mmeijeri]

I first saw the basic concept of displacement pumps of this type in 1960, in Felix Goodwin's "Exploration of the Solar System" but his idea used a membrane.  A number of others, including John Whitehead at LLNL, have built and tested piston pumps, and John even flew one about fifteen years ago. Steve has added to the technology base by demonstrated pumping without a membrane or pistons.

How does this compare to a compressed-air turbopump efficiency-wise?

[baldusi]

I am at a loss as to why a propellant pressurization system so much less expensive than turbopumps and with equivalent performance and likely better reliability has not seen commercial development.

Any speculation?

Are you sure of those statements? have you given it thought to what happens to the "smoothness" of the pressure flow and how would that affect a controlled deflagration that is a liquid rocket main combustion chamber?

[HMXHMX]

I am at a loss as to why a propellant pressurization system so much less expensive than turbopumps and with equivalent performance and likely better reliability has not seen commercial development.

Any speculation?

Are you sure of those statements? have you given it thought to what happens to the "smoothness" of the pressure flow and how would that affect a controlled deflagration that is a liquid rocket main combustion chamber?

And in the last ten or so years TPAs have gotten ridiculously cheap.

[S.Paulissen]

This thing looks like POGO instability hell at scale.  But I'm no aerospace engineer.

[mmeijeri]

And in the last ten or so years TPAs have gotten ridiculously cheap.

In addition, if I understand it correctly, dealing with hot gas is what makes turbines difficult and dealing with very cold and low-density LH2 is what makes pumps difficult. A low temperature gas turbopump for LOX, kerosene or methane should be much cheaper than a turbopump for a LOX/LH2 gas generator / SC engine. That's why I was wondering about a compressed air (or helium) turbopump, as it seems like a far more straightforward, almost off-the-shelf solution compared to a pistonless pump.

[tdperk]

This thing looks like POGO instability hell at scale.

Actually the pump chamber inlet valve is just a check valve.  It can't seat until pressure equalization across the orifice it represents to the propellant flow sees no pressure drop--which can only be true when there is almost no flow.

So not only no POGO, it is an immense damper to POGO.