A Space & astronomy forum. SpaceBanter.com

Go Back   Home » SpaceBanter.com forum » Space Science » Technology
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

A third way for rockets?



 
 
Thread Tools Display Modes
  #1  
Old January 27th 04, 09:30 AM
Remy Villeneuve
external usenet poster
 
Posts: n/a
Default A third way for rockets?

Found interesting things on the Web tonight:

http://www.flometrics.com/rockets/ro...rocketpump.htm

Very, very interesting approach... I'm even tempted to say that it's
too good to be true, to have the possibility of "best of both worlds"
applications.

How big do you thing such a design can be scaled?

Can it be used for low-tech liquid-fueled boosters in the near term?
  #2  
Old January 28th 04, 10:01 AM
Oren Tirosh
external usenet poster
 
Posts: n/a
Default A third way for rockets?

(Remy Villeneuve) wrote in message . com...
Found interesting things on the Web tonight:

http://www.flometrics.com/rockets/ro...rocketpump.htm

Very, very interesting approach... I'm even tempted to say that it's
too good to be true, to have the possibility of "best of both worlds"
applications.


It has interesting properties but I wouldn't go as far as "too good to
be true". The weight and complexity of such a pistonless pump is not
trivial. It has lots of pressure vessels and valves and an oversized
pressurization system because it needs 1:1 volume of
pressurantropellant. Pressurant must be compatible with both
propellants in its chemistry and temperature.

How big do you think such a design can be scaled?


There don't seem to be any special scaling limit.

Can it be used for low-tech liquid-fueled boosters in the near term?


Yes. I believe a demonstration vehicle should be within the
capabilities of serious amateurs.
  #3  
Old January 28th 04, 07:48 PM
Iain McClatchie
external usenet poster
 
Posts: n/a
Default A third way for rockets?

One nice thing about that pump design that I don't see mentioned on the
website is that, although you need as much pressurant as you would if the
main tanks were pressurized to the pump delivered pressure, you vent most
of that pressurant on the way up, and don't need to accelerate it.

Oxidizer tanks especially have significant pressurant weights at burnout.

The large pressurant requirements for a design like this pretty much means
they are going to have to boil something if they are going to orbit.
Whatever they boil is going to have to be supplied or boosted to high
pressure. Whatever contains or boosts that pressurant is going to weigh
something, and I don't see that factored into their mass calculation.

But I still think it's a great idea.
  #4  
Old January 29th 04, 03:18 AM
James Graves
external usenet poster
 
Posts: n/a
Default A third way for rockets?

Remy Villeneuve wrote:

http://www.flometrics.com/rockets/ro...rocketpump.htm

Very, very interesting approach... I'm even tempted to say that it's
too good to be true, to have the possibility of "best of both worlds"
applications.

How big do you thing such a design can be scaled?


Not that I'm an expert, but I don't see any reason it can't be scaled up
to an arbitrarily large size. It would also be possible to have
multiple pumps, if necessary. Or pumps with more than two high-pressure
cylinders.

Can it be used for low-tech liquid-fueled boosters in the near term?


Practically speaking, only if the company is very liberal (and cheap)
with his patent licensing. The big aerospace companies aren't going to
change their designs for this. The existing engineering teams will find
plenty of reasons not to give it a try.

So his only hope (in the near term) of seeing this fly is to convince
one of the X-Prize teams to try it. Not that it would be a factor for
the competition itself. But some of the teams like Armadillo will (I
believe) continue working, even if they don't win the race.

Flowmetrics will have to get some good flight data though, before other
people will be willing to experiment with it.

At any rate, I have some doubts about the amount of pressurant needed.
I haven't yet read all the info on the site, but it seems to me
(intuition can always be wrong) that they would need a lot more
pressurant than a traditional pressure-fed design. That's because
you're blowing out large quantities of it with each pump cycle. They're
talking about heating it, which should reduce the amount needed.
Perhaps I need to run some numbers.

James Graves
  #5  
Old January 30th 04, 07:30 AM
Iain McClatchie
external usenet poster
 
Posts: n/a
Default A third way for rockets?

This design has to heat the pressurant. The hot pressurant cycles
through the pump chambers with the propellants. If the propellants
are cyrogenic, there is going to be a fair bit of heat transfer to
the propellant. More than you would see in a comparable pressurized
main tank, since a big tank can use diffusers and stratify the
pressurant in the tank.

That means more, maybe a lot more pressurant will be needed, since
the colder pressurant will contract.
  #10  
Old February 3rd 04, 09:47 AM
Jordin Kare
external usenet poster
 
Posts: n/a
Default A third way for rockets?

Remy Villeneuve wrote:

Found interesting things on the Web tonight:

http://www.flometrics.com/rockets/ro...rocketpump.htm

Very, very interesting approach... I'm even tempted to say that it's
too good to be true, to have the possibility of "best of both worlds"
applications.


We looked at this type of pump for Mockingbird (LLNL concept for a small
SSTO vehicle), and as I recall Mitch Clapp also looked at it for his
Bricklifter (slightly earlier version of the same thing); as with many
ideas, it's been around for a while. It was probably invented by
Tsiolkovsky; everything else was :-).

We found that for our size vehicle, a small, rapid-cycling piston pump
was better than a large, slow-cycling pistonless configuration such as
Flometrics is describing. Among other things, the piston separates the
pressurant gas from the propellant, allowing the use of a much hotter
pressurant, and by using a differential piston (gas end larger diameter
than liquid end), you can make the system self-pressurizing. And the
piston maintains propellant flow in zero-G, so it's better for a
restartable engine; no need to settle propellants before you can
restart.


How big do you thing such a design can be scaled?


There's no obvious upper limit, but "reciprocating" systems tend not to
scale up as well as rotating systems; at some point the cost and mass of
the valves required for this system will exceed the cost and mass of
turbopumps. The crossover for our approach was around 50,000 lbf total
thrust.

Can it be used for low-tech liquid-fueled boosters in the near term?


Possibly, but actually making a complex set of valves work reliably is
not trivial; note that many pressure-fed liquid and hybrid vehicles have
failed because of valve failures even though they have only one or two
valves that only need to operate once. As another example, John
Whitehead at LLNL, the guru of piston pumped propulsion, was never able
to get electrically-operated valves working reliably for propulsion
pumps despite a couple of years of effort; he eventually switched to
mechanical valves.

Jordin Kare
Kare Technical Consulting
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT +1. The time now is 10:57 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 SpaceBanter.com.
The comments are property of their posters.