Steam rocket

[tallguy]

Despite the premature parachute deployment during Evel Knievel's 1974 attempt to jump his Skycycle across the Snake River canyon, this kind of propulsion seemed to work okay.

Much later, Eddie Braun used a similar rocket-powered vehicle when he successfully jumped over the Snake River
canyon.  He reportedly reached a speed exceeding 400 mph in less than 5 seconds, and it's not difficult to
find an online video showing this feat.

This kind of vehicle, applied to land speed racing, should be relatively inexpensive and less complex, compared
to one using a jet engine.

Decades ago, I had an idea of how to build -- and finance -- a series of steam rocket cars, each one faster than the previous one.

It should be convenient and inexpensive to discuss possibilities here.  Who's interested?

[tallguy]

I'm still interested.  However, there's a lot of difference between 400 mph in the air and (about) 800 mph on a dry
lake bed.  I'm not sure that a tank of superheated water can store enough thermal energy to propel a car to this speed
using thrust alone.  The combined mass of the water, tank, frame, body, wheels, driver, and other important items would resist being accelerated.  And of course, wind resistance plays a huge role.

My financing idea, starting decades ago, was to build a relatively slow, relatively inexpensive rocket car and charge people for the opportunity to drive the thing.  For their money, the drivers would also get bragging rights and photos,
and perhaps a certificate indicating that they drove the rocket-powered car.  The first one of these cars would likely be not much more than a go-cart with a small tank and a small rocket engine.  Of course, safety would have to be a high priority.  And this would present several challenges . . . such as how to profit from this, in order to finance the build of the next (faster, more-expensive) rocket car.  Another challenge would be in finding a suitable place to run the car.  Many
(if not most) drag strips have banned rocket cars.  And a steam rocket would tend to deposit water on the track.  Not
what a drag strip really should have, right where most of the race vehicles are looking for traction.

[MalcolmUK]

In the UK the steam rocket project which is proving that the concept works for short thrust duration is the Force of Nature bike of Graham Sykes. My own car - The Rickman Metisse - was built, because I could not finance the land speed rocket single seater I wanted to run. I had a mobile steam generator to 'fill' the pressure vessel. Constructing to British Standards of Engineering (required by the governing body and venue owners) meant a heavy pressure vessel. On an unprepped drag racing track any water will evaporate and leave the surface unaltered. 'Abandoned' airfields or a firm sandy beach would have been the speed record track. High pressure steam can be a danger, but I spent a large proportion of my working life with steam boilers installed in UK industrial sites. Malcolm.         

[tallguy]

Malcolm, thank you for this information.

[tallguy]

I'm still researching this kind of thing, based on actual history of what has been done and how
well it has worked.  Knievel's Skycycle apparently had 200 lbs. of water, heated to 500 degrees F.
This suggests that the pressure in the (titanium, insulated) tank was about 660 psi at the time of launch.  In this vehicle, the tank appeared to be approximately spherical.  In a land speed car, the
tank would more likely be shaped like a sausage, with hemispherical ends.  It would likely be insulated, and utilize heating from an outside source of energy right up to the last few seconds
prior to the timed run.  Various ways to keep the superheated water in the tank hot are being
explored, including the use of electrically-heated filament(s) . . . possibly made of nichrome.

[SPARKY]

what shape would you use for the exhaust nozzel

[tallguy]

Most likely a converging/diverging nozzle (fairly typical), with a conical total included angle of about
30 degrees.  Perhaps the nozzle would extend far into the tank.  I recently read about the
(claimed-to-be-supersonic) run of the Budweiser Rocket, which was a fairly short run.  I tend to think in terms of a longer total acceleration distance, with less G's of acceleration. 

Lots of research and calculations are yet undone.  I like the idea of a titanium tank, as this material
is fairly strong for its weight and retains a good amount of strength at elevated temperatures
(such as 500 degrees F).  As a possible alternate -- instead of using an electric heating system for
the superheated water -- I could also imagine flame heating from underneath the tank until just a few seconds before launch.   If the tank is (for example) about 20 feet long, a manifold lying on the
ground could supply a bunch of oxyfuel flames, closely spaced and aiming upward, playing on the
bottom of the tank.  This part of the tank, perhaps, being a bit hotter than the rest of the
tank, might be a little thicker.  Propane is still relatively easily available.  A major challenge, however, might be in making the second record run promptly (in the opposite direction) after the
first run.  And it's also my understanding that SCTA rules may well prohibit the obvious discharge
of water onto the race track.  I don't know the rules for all the existing sanctioning organizations.
 

[SPARKY]

What about running the heat through your tank like conventional boiler tubes but reversed?

[tallguy]

What about running the heat through your tank like conventional boiler tubes but reversed?

I'm not sure I understand this . . . but am trying to imagine a tank with a tube penetrating the
tank's wall(s) in 2 locations, and perhaps winding back-and-forth -- inside the tank -- between the two locations.  Playing a flame into one end of the tube would heat it, and the heat would then transfer to the water.  Is this what you mean?  I'm not an expert on "conventional boilers". 

I seem to remember seeing -- years ago, online -- a picture posted by Juan Manuel Lozano, showing a fairly large tank with some tubes penetrating it.  For purposes of heating the water in the tank.  If I remember correctly, there were 3 tubes, and each of them passed straight through (all the way through) the tank ends . . . and were welded in place.  I think he knows his stuff.

[tallguy]

I recently read about hydrogen peroxide rocket engines, in which the generated steam can reach
temperatures exceeding 1100 degrees F.  This is substantially more than 500 degrees F, which is
more typical in simple steam rocket vehicles.  That higher temperature represents the potential for improved performance, compared to a simple engine using pre(super)heated water.  Yes, added complexity and cost can be associated with more performance.  But for now, I am still researching the simple version.  Even it would be quite expensive (and we've already known this for some time).

[manta22]

What about running the heat through your tank like conventional boiler tubes but reversed?

I'm not sure I understand this . . . but am trying to imagine a tank with a tube penetrating the
tank's wall(s) in 2 locations, and perhaps winding back-and-forth -- inside the tank -- between the two locations.  Playing a flame into one end of the tube would heat it, and the heat would then transfer to the water.  Is this what you mean?  I'm not an expert on "conventional boilers". 

I seem to remember seeing -- years ago, online -- a picture posted by Juan Manuel Lozano, showing a fairly large tank with some tubes penetrating it.  For purposes of heating the water in the tank.  If I remember correctly, there were 3 tubes, and each of them passed straight through (all the way through) the tank ends . . . and were welded in place.  I think he knows his stuff.

Hydrogen peroxide rockets have been around for a long time. Search for "ME-163".

[tallguy]

What about running the heat through your tank like conventional boiler tubes but reversed?

I'm not sure I understand this . . . but am trying to imagine a tank with a tube penetrating the
tank's wall(s) in 2 locations, and perhaps winding back-and-forth -- inside the tank -- between the two locations.  Playing a flame into one end of the tube would heat it, and the heat would then transfer to the water.  Is this what you mean?  I'm not an expert on "conventional boilers". 

I seem to remember seeing -- years ago, online -- a picture posted by Juan Manuel Lozano, showing a fairly large tank with some tubes penetrating it.  For purposes of heating the water in the tank.  If I remember correctly, there were 3 tubes, and each of them passed straight through (all the way through) the tank ends . . . and were welded in place.  I think he knows his stuff.

Hydrogen peroxide rockets have been around for a long time. Search for "ME-163".

The capability/utility of hydrogen peroxide rockets has been amply demonstrated.
I witnessed a run -- by the Pollution Packer car (powered by hydrogen peroxide)
in the early '70s.  It ran 312 mph in 4.97 seconds on a drag strip in Ontario, CA.

But my interest in using peroxide is quite limited, due to the associated chemical
hazards and limited availability (largely due to legal reasons) of the stuff.  I'm still
interested in exploring possibilities using just heated water for propulsion, due to
the relative simplicity and relatively low cost.  Of course, calculations to determine
the functional practicality of this are still in order.  And (it goes without saying that)
raising money for the project would always be a major consideration/challenge.

Just for the sake of initial inquiry, how much would you be willing to pay someone,
on a dry lakebed -- such as the Alvord Desert, in southern Oregon, to let you drive
a steam-powered car that could go from 0-100 mph in about 8 seconds?  I know
that there are street-legal cars that can do this, but they are not very unusual or
unique, compared to a rocket-powered car.  I'd be willing to pay $100 (or more)
to make a run like this in someone's rocket car, and also have the run videotaped
by a friend.  Just for the experience and bragging rights.  But $100 may not be
enough to justify having the car's owner(s) and crew set it all up for a run.  Even
$200 or $300 per run might not be enough, assuming they would plan to have
perhaps 20 runs happen in a day, charging a bunch of folks like me for this
experience.  But there's a lot of money out there.  I'd pay more to go faster, but
of course, it would not be very smart to let anybody with money climb into a
rocket car and immediately (with no prior experience or demonstration of skill)
go (say) 200 mph.  Safety would have to be of paramount importance.  So if I
ran the operation, I'd require that first-time customers/drivers make at least one
slow run, in order to qualify for a faster run.  And the faster the run, the higher
the price would have to be.  I could easily imagine that the cost of the "initial"
(slowest) steam-powered car for this venue could exceed $10,000, and the miscellaneous other costs to get it (and a crew) to the lake bed could add another
$10,000.  All this with no guarantee of any paying customers.  It would have to
be treated like a business proposition, before investing significant money that is
so hard to find.  Meanwhile, thinking and planning are relatively inexpensive by
comparison.  There could be a 100 mph "hat", a 200 mph "hat", etc.  Or something
similar.  I have yet to drive 200 mph.  But I have been in a jet aircraft that may
have exceeded 200 mph before takeoff.

[tallguy]

In all the times I have flown in a commercial jet, the acceleration (at takeoff) was probably less than 1G.  I was, however, once given a ride -- as a passenger -- in a new Tesla Plaid that had more than 1000 hp and 4WD.  The acceleration was about
1.3G, and I almost passed out from it.  I would not want to subject my "customers" to much more acceleration than that.

Yes, I am aware that top fuel dragsters accelerate much faster, and their drivers somehow manage to stay conscious and in good control of the vehicle most of the time.  I'd rather err on the side of safety, because in land speed racing, the events and experiences are not profit-driven -- and I don't want to compromise physical safety -- especially if there's no potential for a lot of monetary gain.

With a large, hot tank of superheated water, a lot of heat loss occurs quickly.  And with a relatively conservative (limited-by-safety-considerations) acceleration, the hot water has more time to cool off during an actual land speed run, thus weakening the steam's performance.  Although there are ways to heat the water during a run, I'd prefer to avoid this expensive and challenging complication.  To go 800 mph over a measured mile would require an awfully huge amount of this hot water . . . perhaps a ridiculously huge -- and impractical -- amount.  It's hard for me to imagine a land speed car with (for example) several tons of superheated water aboard.  It would probably make sense to do a bunch of thermal calculations relating to this, before getting much more serious about designing such a vehicle. 

I remain confident, nonetheless, that there's a lot of excess money in various coffers, and that if an effective design for this vehicle is developed, the money could become available.

I don't want to design for a 100 mph steam car, followed by designing for a 200 mph
steam car, etc. -- if it isn't practical to eventually build an 800 mph steam car.  So
I will do my early designs based on the ultimate (i.e., 800 mph) goal.  Thank you
to all who read this.

[tallguy]

Competing per SCTA rules require a prompt backup run in the opposite direction of the earlier run.
For this reason, using just a steam rocket to propel the vehicle could be very impractical, if not
impossible . . . unless the race team is (almost literally) made of money.  I can imagine a pre-filled
tank of superheated water being ready to be installed right after the empty tank is removed . . .
but who really has that kind of money and an interest in spending it that way?  I wish it were me.

And then there's the issue of depositing water on the race track.  Doing that intentionally may
be an outright violation of SCTA rules, even if done on private time other than at an organized
larger meet -- such as Speed Week.  I suppose that perhaps a request could conceivably be made
to alter the rule(s) about that, in order to allow for this . . . but even so, there's quite a challenge
regarding how much thermal energy can be stored in the superheated onboard water, and how
much the loaded vehicle weighs, and how streamlined it is, and how quickly the onboard water
loses heat during a run.  All quite challenging stuff.

[7707]

Can I suggest you check out GRAHAM SYKES Steam Rocket Bike. It?s on YouTube. He is based in the UK and has some pretty impressive stats.