Landracing Forum
Tech Information => Technical Discussion => Topic started by: Ratliff on June 01, 2008, 09:37:22 PM
-
Performance spreadsheet showed potential top speed of over 950 mph with mile average of over 880 mph.
-
Discussion of design issues (pages 1 and 2)
-
Discussion of design issues (page 3)
-
Discussion of design issues (page 4)
-
As Dolan would say..............
Hypothetrical cars set hypothetrical records.
Geesh I can't believe I just did that..........
-
I don't think I'd want to be anywhere near a boiler that produced enough steam to propel ANYTHING to 880 mph.
-
I don't think I'd want to be anywhere near a boiler that produced enough steam to propel ANYTHING to 880 mph.
No boilers involved in the car itself. The tanks in the car would just be storage tanks. The water would be heated externally in a separate boiler then pumped into the car. Maximum operating pressures would be around 400 psi.
-
As Dolan would say..............
Hypothetrical cars set hypothetrical records.
Geesh I can't believe I just did that..........
AWWWW you miss him too
-
As Dolan would say..............
Hypothetrical cars set hypothetrical records.
Geesh I can't believe I just did that..........
Yeah, just like that hypothetical 500 mph record Doug Herbert is going to set.
-
I don't think I'd want to be anywhere near a boiler that produced enough steam to propel ANYTHING to 880 mph.
http://www.steamcar.co.uk/
If you want to see a steam car that not only has boilers but will be operating at much higher pressures than a steam rocket car, there will be one at this year's Speedweek.
-
The 21% empty weight fraction and the attending ~10% structural fraction for a 1500 to 2000 psf vehicle are more than a factor of 2 away from being rational.
This is a difficulty that I have run into with a lot of the people "designing" ALSR cars. Stresses are factors of 4 to 6 greater than any wheel driven car, 10X for Mach 2. Think about that factor of 10 very carefully. The design database of supersonic-at-sea-level capable aircraft and missiles provides plenty of structural weight and design guidance that simply cannot be ignored.
If anyone wants to pencil out something like this, a 1000 mph FIA record requires a 35 to 40% structural mass fraction with advanced materials, straight load paths, and good structural design. Poor design or heavy materials can raise this to 60 to 75%. Note that the "structural" mass fraction does not include the engine.
For reference, the structural fraction of our current project is nearly 60% due to the use of mild steel and a far-from-optimum structural layout. Thrust SSC was about 50%. 10% is irrational. :-o
-
The 21% empty weight fraction and the attending ~10% structural fraction for a 1500 to 2000 psf vehicle are more than a factor of 2 away from being rational.
This is a difficulty that I have run into with a lot of the people "designing" ALSR cars. Stresses are factors of 4 to 6 greater than any wheel driven car, 10X for Mach 2. Think about that factor of 10 very carefully. The design database of supersonic-at-sea-level capable aircraft and missiles provides plenty of structural weight and design guidance that simply cannot be ignored.
If anyone wants to pencil out something like this, a 1000 mph FIA record requires a 35 to 40% structural mass fraction with advanced materials, straight load paths, and good structural design. Poor design or heavy materials can raise this to 60 to 75%. Note that the "structural" mass fraction does not include the engine.
For reference, the structural fraction of our current project is nearly 60% due to the use of mild steel and a far-from-optimum structural layout. Thrust SSC was about 50%. 10% is irrational. :-o
Craig Farnsworth, brother of Blue Flame co-builder Pete Farnsworth, is a missile engineer.
Steam rockets operate in the 250 to 400 psi range.
When one DOES THE MATH and examines various tank configurations, a 4,000 pound empty weight car with sufficient volume to hold 13,000 pounds of water may very well be feasible.
-
Page 2
-
Page 3
-
Page 4
-
Pages 5 and 6
-
The 21% empty weight fraction and the attending ~10% structural fraction for a 1500 to 2000 psf vehicle are more than a factor of 2 away from being rational.
This is a difficulty that I have run into with a lot of the people "designing" ALSR cars. Stresses are factors of 4 to 6 greater than any wheel driven car, 10X for Mach 2. Think about that factor of 10 very carefully. The design database of supersonic-at-sea-level capable aircraft and missiles provides plenty of structural weight and design guidance that simply cannot be ignored.
If anyone wants to pencil out something like this, a 1000 mph FIA record requires a 35 to 40% structural mass fraction with advanced materials, straight load paths, and good structural design. Poor design or heavy materials can raise this to 60 to 75%. Note that the "structural" mass fraction does not include the engine.
For reference, the structural fraction of our current project is nearly 60% due to the use of mild steel and a far-from-optimum structural layout. Thrust SSC was about 50%. 10% is irrational. :-o
Three tanks, each 25 feet long and two feet in diameter, arranged two on top and one on the bottom, would hold over 1,700 gallons (13,600 lbs) of water. Total length of the car would be 33 to 35 feet long. Even using conventional steels, instead of titanium, an empty weight of 4,000 lbs for a steam rocket car of these dimensions could be very doable.
-
In these photos of a hydrogen peroxide rocket land speed car under construction back in the mid-eighties, it can be seen how concentric tanks can be arranged to serve as part of a car's structure.
-
Craig Farnsworth, brother of Blue Flame co-builder Pete Farnsworth, is a missile engineer.
When one DOES THE MATH and examines various tank configurations, a 4,000 pound empty weight car with sufficient volume to hold 13,000 pounds of water may very well be feasible.
Glad you brought that up.
Let's see... the last three successful ALSR cars (and one hopefully in the future) were designed by:
Thrust SSC: Ron Ayres and Glynn Bowsher, a missile engineer and a top ME.
Fossett LSR: Craig Breedlove and Eric Ahlstrom, a 5 time ALSR holder and a rocket scientist.
Thrust 2: John Ackroyd, a world recognized ME
Blue Flame: Dick Keller and Pete Farnsworth, rocket scientists would be an apt description.
And the structural fractions were...
51%
53 to 58% (depending on mod state)
60%
63%
Pretty narrow range there... Not too close to 10% either.
Now in concert with this august company, I claim that 60 to 75% is rational for a poor design and half of that is good design. Only a fool would claim that he could reduce the weight fraction by a factor of 6 and stand up to DOUBLE the dynamic pressure. Please stop with the irrational and unsupportable claims. While the historical documents are interesting for perspective, this "steam rocket fantasy" is equivalent to saying that we could build a 1200 lb Goldenrod to go 650 mph wheel driven.
It's
Not
Rational.
-
Craig Farnsworth, brother of Blue Flame co-builder Pete Farnsworth, is a missile engineer.
When one DOES THE MATH and examines various tank configurations, a 4,000 pound empty weight car with sufficient volume to hold 13,000 pounds of water may very well be feasible.
Glad you brought that up.
Let's see... the last three successful ALSR cars (and one hopefully in the future) were designed by:
Thrust SSC: Ron Ayres and Glynn Bowsher, a missile engineer and a top ME.
Fossett LSR: Craig Breedlove and Eric Ahlstrom, a 5 time ALSR holder and a rocket scientist.
Thrust 2: John Ackroyd, a world recognized ME
Blue Flame: Dick Keller and Pete Farnsworth, rocket scientists would be an apt description.
And the structural fractions were...
51%
53 to 58% (depending on mod state)
60%
63%
Pretty narrow range there... Not too close to 10% either.
Now in concert with this august company, I claim that 60 to 75% is rational for a poor design and half of that is good design. Only a fool would claim that he could reduce the weight fraction by a factor of 6 and stand up to DOUBLE the dynamic pressure. Please stop with the irrational and unsupportable claims. While the historical documents are interesting for perspective, this "steam rocket fantasy" is equivalent to saying that we could build a 1200 lb Goldenrod to go 650 mph wheel driven.
It's
Not
Rational.
Thrust 2 was a tank that broke Gabelich's mile record but could not exceed his kilo record by the required 1%. And that was after Thrust 2 accelerated for six miles!
-
Craig Farnsworth, brother of Blue Flame co-builder Pete Farnsworth, is a missile engineer.
When one DOES THE MATH and examines various tank configurations, a 4,000 pound empty weight car with sufficient volume to hold 13,000 pounds of water may very well be feasible.
Glad you brought that up.
Let's see... the last three successful ALSR cars (and one hopefully in the future) were designed by:
Thrust SSC: Ron Ayres and Glynn Bowsher, a missile engineer and a top ME.
Fossett LSR: Craig Breedlove and Eric Ahlstrom, a 5 time ALSR holder and a rocket scientist.
Thrust 2: John Ackroyd, a world recognized ME
Blue Flame: Dick Keller and Pete Farnsworth, rocket scientists would be an apt description.
And the structural fractions were...
51%
53 to 58% (depending on mod state)
60%
63%
Pretty narrow range there... Not too close to 10% either.
Now in concert with this august company, I claim that 60 to 75% is rational for a poor design and half of that is good design. Only a fool would claim that he could reduce the weight fraction by a factor of 6 and stand up to DOUBLE the dynamic pressure. Please stop with the irrational and unsupportable claims. While the historical documents are interesting for perspective, this "steam rocket fantasy" is equivalent to saying that we could build a 1200 lb Goldenrod to go 650 mph wheel driven.
It's
Not
Rational.
The genius cars were the first and second J-79 cars built by Art Arfons, a world recognized hot rodder and drag racer. Both cars were more compact than Thrust 2. The second J-79 car was also much lighter than both the first J-79 car and Thrust 2. Arfons clocked 571 mph through the kilo on only his fifth timed run with the first J-79 car. The first J-79 car set records of 434 mph, 536 mph, and 576 mph in a total of eight timed runs.
-
More detail on Arfons second J-79 land speed car.
Below are links to photos of the second J-79 car in action at dragstrips.
http://www.the-rocketman.com/rocket_cars/JET-ART-ARFONS-J79-CAR-U_lg.jpg
http://www.the-rocketman.com/rocket_cars/JET-ART-ARFONS-J79-CAR_lg.jpg
-
Craig Farnsworth, brother of Blue Flame co-builder Pete Farnsworth, is a missile engineer.
When one DOES THE MATH and examines various tank configurations, a 4,000 pound empty weight car with sufficient volume to hold 13,000 pounds of water may very well be feasible.
Glad you brought that up.
Let's see... the last three successful ALSR cars (and one hopefully in the future) were designed by:
Thrust SSC: Ron Ayres and Glynn Bowsher, a missile engineer and a top ME.
Fossett LSR: Craig Breedlove and Eric Ahlstrom, a 5 time ALSR holder and a rocket scientist.
Thrust 2: John Ackroyd, a world recognized ME
Blue Flame: Dick Keller and Pete Farnsworth, rocket scientists would be an apt description.
And the structural fractions were...
51%
53 to 58% (depending on mod state)
60%
63%
Pretty narrow range there... Not too close to 10% either.
Now in concert with this august company, I claim that 60 to 75% is rational for a poor design and half of that is good design. Only a fool would claim that he could reduce the weight fraction by a factor of 6 and stand up to DOUBLE the dynamic pressure. Please stop with the irrational and unsupportable claims. While the historical documents are interesting for perspective, this "steam rocket fantasy" is equivalent to saying that we could build a 1200 lb Goldenrod to go 650 mph wheel driven.
It's
Not
Rational.
The recoverable reuseable solid rocket boosters on the shuttle each weigh about 100,000 lbs empty and 1,000,000 lbs loaded. That's nine times the structure weight in propellant. The steam rocket car would only need to hold about three times the structure weight in propellant.
With a weight of about 7.5 lbs per square foot for 3/16" steel sheet, a tank 25 feet long and 2 feet in diameter would have about 1,180.125 lbs of steel in its skin. Don't know what the weight from the end caps would be. So with the configuration of three 25 foot long 2 foot diameter tanks I described earlier, the steam rocket car using steel tanks would have about 3,540.375 lbs of steel in the tank skins (about the same weight as a J-79 engine). Using titanium instead of steel for the tanks would cut the tank weight in half. If titanium instead of steel were used for the tanks, the 4,000 lbs empty weight used in Craig Farnsworth's performance calculations would be attainable and very realistic.