FYI, there are no pictures on that site of a Ford Explorer, that is a F-150 pickup truck. The F-150 rides on a traditional truck lader frame whereas the Explorer 'chassis' is a car-like unibody construction.
Over the years the organizers have looked upon sailing fairly kindly so long as the car met the dimensional requirements. Team New England/Santa Cruz's Pumpkinseed and one of the early Solar Motions cars also had sails. Rumor was that they were able to see a difference in performance but it wasn't enough to overcome other shortcomings in the vehicle. The TNE/SC and Solar Motions cars had, I think, active control of the angle of attack of their sails. Most well designed solar cars passivly sail in a cross wind, and this effect can contribute significant reductions in overall aerodynamic drag.
However, sailing can also induce a lot of sideforce on the tires and increases the rolling resistance and shortens tire life.
An excellent book on solar car aerodynamics is The Leading Edge by Goro Tamai.
Actually, in the technical regulations of the race, section B paragraph 2, battery capacity is specified as an allowable mass for a given chemistry.
for instance: Pb Acid is allowed 125kg (assumed 40Wh/kg) Ag/Zn is allowed 40kg (assumed 125Wh/kg) Li-ion is allowed 35kg (140Wh/kg)
It doesn't take too much searching to find batteries that exceed those energy densities. Particularly if you overcharge your chemistry you could be looking at 5.2 to 5.3kWh which is nice little cushion to burn in the sprint from Darwin to Katherine.
If memory serves, Autozone is one of those multi-billion companies that have bet the operation on using Linux in their point-of-sale system. Last time, I checked they were doing fairly well.
Granted, they were sued by their former software vendor after switching to Linux, but that's another story.
The biggest difference is the stop in Albuquerque was changed from 2.5hrs to a staged stop. This changed the the long leg from Rolla, MO to Barstow into a set of two sprints. The strategy for racing them are very different. In '01 the leaders were caught under cloudcover near Albuquerque, which slowed us down on the climb to Flagstaff. With a staged stop in Albuquerque it is possible to sprint all the way up to Flagstaff without worry of cloudcover.
Sunswift's cells were grown in-house at UNSW and are far smaller than 10 x x 10cm. In fact, they also developed their own lamination technique, which was pretty slick. It was one of the more impressive vehicles at the 2001 World Solar Challenge.
According to astronautix.com, those are the LEO numbers for the Atlas V. They quote a lower number for the DIV-Heavy to Leo at 25,800kg.
The big difference between the DIV and the Atlas V comes when you compare other variants. The Atlas V 401 can lift 12,000kg to LEO while a DIV-Medium can only lift 8600kg to LEO.
if they were vegtable based, then they wouldn't be synthetic now would they?
Motor oil is engineered to keep your engine running. Vegtable oil is ment for cooking. You're more than welcome to try it in your car though. I take no responsibility for what happens.
I'd imagine that by the time commercially produced diesel fuel is put in the tank of a vehicle it has a lot less filter clogging crap in it than recycled vegtable oil.
And back in the fifties doctors were worried that man might not be able to survive in a weightless environment. Then they began to wonder if they could survive the trip to the moon, and so on and so forth. You never know until you try.
I was under the impression that Glushko's designs to produce the same thrust and Isp with a single chamber would have reslted in serious acoustic instabilities. The simple solution was to drive four smaller chambers off a single set of turbopumps. We solved the same problem in the F-1 with baffles. I think that was in Harford's book on Korolov.
The soyuz rocket doesn't actually have 20 engines. It's actually five engines (five pairs of fuel and oxidizer turbopumps) each with four combustion chambers. The RD-171 used to power the Zenit is designed the same way. Or for that matter, the RD-180 that will power the Atlas 5 is little more than a RD-171 minus two of the combustion chambers.
The NK-15 was actually used on the N-1. The NK-33 are the modified NK-15 engines sold to Kistler. The NK-15 is based off the design for the NK-9.
The engines in the R-7, the RD-107/108, were single turbopumps (one for fuel and one for oxidizer) driving four combustion chambers. The reason for four combustion chambers was to deal with acoustic problems inside the chamber. The F-1 had similar acoustic problems, but they were solved with baffles inside the chamber. The RD-170/171/180 are also multiple chambers driven by single fuel and oxidizer turbopumps.
Glushko's bureau did the N2O4-hydrazine engines for the UR-500 (Proton). The UR-700 was never built.
There were a lot of reasons for the failure of the N-1. Mishin's competence as an engineer had nothing to do with it. Korolov was successful because he had the ear of Kruschev and was good at motivating his people. When Kruschev was removed from power in 64, some would argue that the drive behind the N-1 went with him, though the last launch wouldn't be until late 1972. There were also the issue of multiple design bureaus getting money to build rockets capable of getting to the moon (Chelomei and Yangel are two that come to mind).
Korolov, like von Braun, made things happen more because of his personality and management skills than engineering prowess.
Jim Harford wrote an excellent book titled Korolov, which presents an excellent picture of his life from childhood to death. There's also quite a bit of information on what happened at his design bureau after his death.
You're right, it just does not burn, which is why the folks at Pratt & Whitney used tetra-ethyl-borane (teb) to light the engines. The low down on TEB is that it was originally a mining explosive that reacts very violently with oxygen. Start the fuel pump, squirt fuel in the combustion section and a squirt of TEB and you're on your way. Want afterburners? Another squirt of TEB to light those.
There's no way you'll ever convince the commercial operators to handle TEB. It's just too dangerous. Heck, NASA is trying to get rid of their nitrogen tetroxide - hydrazine based auxiliary power units because the fuels are so dangerous (toxic) to handle, and they're pros at handling that stuff. Too boot, they're willing to take a weight penalty to do it. But I digress.
I don't pretend to be an expert, but here is some information I've found in the past few minutes looking up info from common sources for propellant info. Most of the information can also be found on www.astronautix.com.
The density of LH2 is about 0.07 g/cc whereas kerosene averages around 0.8 g/cc. Liquid hydrogen has an energy density of 141 MJ/kg vs 46 MJ/kg for kerosene.
Hydrogen is usually commercially produced from steam reforming of natural gas, though processing of other hydrocarbons is possible. According to DOE, electrolosys is not likely to become the predominant means of producing large quantities of hydrogen.
And the vast majority of the weight in the External Tank is to hold the hydrogen because of it's low density, even when liquified.
The next logical extension is the extra volume required by an airplane to carry LH2 over kerosene. Is the weight penalty of larger tanks and extra drag from larger surface area worth the environmental benefits of using hydrogen. Not to mention that between SNECMA, GE AE, Pratt & Whitney, and Rolls Royce none of them produce gas turbines that can burn hydrogen.
Don't forget that the SR-71 was developed from a lot of work that went into designing a hydrogen fueled aircraft. When the design became too heavy and range estimates fell like a rock it was abandoned in favor of hydrocarbons.
No, you want to swallow the shock wave, as this is providing the necessary compression to run the engine. Look at it this way, you want maximum compression to get more thrust out of the engine (Hill & Petterson is an excellent reference). When the shock wave is expelled from operating at off nominal conditions, the compression falls sharply and the engine produces little thrust in comparison to it's brother sitting on the other side of the aircraft. NACA did a lot of research in the 1950's on controlling the shockwave produced by the diffuser. In addition to moving the diffuser for-aft you can also play with the fuel ratio to change the back pressure in the combution zone, and that can sometimes be enough to prevent the expulsion of the shock.
Slashdot Mirror
This is a rehash of a post from 2009:
http://hardware.slashdot.org/story/09/01/25/1831240/Nuclear-Archaeology-Inspires-Replica-of-Hiroshimas-Little-Boy
Which referenced a piece written in 2008:
http://www.newyorker.com/reporting/2008/12/15/081215fa_fact_samuels
FYI, there are no pictures on that site of a Ford Explorer, that is a F-150 pickup truck. The F-150 rides on a traditional truck lader frame whereas the Explorer 'chassis' is a car-like unibody construction.
Over the years the organizers have looked upon sailing fairly kindly so long as the car met the dimensional requirements. Team New England/Santa Cruz's Pumpkinseed and one of the early Solar Motions cars also had sails. Rumor was that they were able to see a difference in performance but it wasn't enough to overcome other shortcomings in the vehicle. The TNE/SC and Solar Motions cars had, I think, active control of the angle of attack of their sails. Most well designed solar cars passivly sail in a cross wind, and this effect can contribute significant reductions in overall aerodynamic drag.
However, sailing can also induce a lot of sideforce on the tires and increases the rolling resistance and shortens tire life.
An excellent book on solar car aerodynamics is The Leading Edge by Goro Tamai.
Actually, in the technical regulations of the race, section B paragraph 2, battery capacity is specified as an allowable mass for a given chemistry.
for instance:
Pb Acid is allowed 125kg (assumed 40Wh/kg)
Ag/Zn is allowed 40kg (assumed 125Wh/kg)
Li-ion is allowed 35kg (140Wh/kg)
It doesn't take too much searching to find batteries that exceed those energy densities. Particularly if you overcharge your chemistry you could be looking at 5.2 to 5.3kWh which is nice little cushion to burn in the sprint from Darwin to Katherine.
If memory serves, Autozone is one of those multi-billion companies that have bet the operation on using Linux in their point-of-sale system. Last time, I checked they were doing fairly well.
Granted, they were sued by their former software vendor after switching to Linux, but that's another story.
The biggest difference is the stop in Albuquerque was changed from 2.5hrs to a staged stop. This changed the the long leg from Rolla, MO to Barstow into a set of two sprints. The strategy for racing them are very different. In '01 the leaders were caught under cloudcover near Albuquerque, which slowed us down on the climb to Flagstaff. With a staged stop in Albuquerque it is possible to sprint all the way up to Flagstaff without worry of cloudcover.
Sunswift's cells were grown in-house at UNSW and are far smaller than 10 x x 10cm. In fact, they also developed their own lamination technique, which was pretty slick. It was one of the more impressive vehicles at the 2001 World Solar Challenge.
According to astronautix.com, those are the LEO numbers for the Atlas V. They quote a lower number for the DIV-Heavy to Leo at 25,800kg.
The big difference between the DIV and the Atlas V comes when you compare other variants. The Atlas V 401 can lift 12,000kg to LEO while a DIV-Medium can only lift 8600kg to LEO.
The -180 is the -170 with half the combustion chambers, and thus half the thrust. The -170 has slightly better performance than the Roketdyne F-1.
if they were vegtable based, then they wouldn't be synthetic now would they?
Motor oil is engineered to keep your engine running. Vegtable oil is ment for cooking. You're more than welcome to try it in your car though. I take no responsibility for what happens.
I'd imagine that by the time commercially produced diesel fuel is put in the tank of a vehicle it has a lot less filter clogging crap in it than recycled vegtable oil.
You know, you could send a robot to Sydney, Australia for New Years and control it from ISS.
You can never replace the experience of actually being there, and taking home the memories of an absolutely wonderful time.
Sending humans may be expensive, but you can NEVER replace the experience of actually going.
And back in the fifties doctors were worried that man might not be able to survive in a weightless environment. Then they began to wonder if they could survive the trip to the moon, and so on and so forth. You never know until you try.
Yes, you are correct. I should have remembered that from Harford's book.
I was under the impression that Glushko's designs to produce the same thrust and Isp with a single chamber would have reslted in serious acoustic instabilities. The simple solution was to drive four smaller chambers off a single set of turbopumps. We solved the same problem in the F-1 with baffles. I think that was in Harford's book on Korolov.
The soyuz rocket doesn't actually have 20 engines. It's actually five engines (five pairs of fuel and oxidizer turbopumps) each with four combustion chambers. The RD-171 used to power the Zenit is designed the same way. Or for that matter, the RD-180 that will power the Atlas 5 is little more than a RD-171 minus two of the combustion chambers.
Wasn't it the engine control system, that caused one of the N-1 boosters to crash back into the pad?
Just to clarify a few things.
The NK-15 was actually used on the N-1. The NK-33 are the modified NK-15 engines sold to Kistler. The NK-15 is based off the design for the NK-9.
The engines in the R-7, the RD-107/108, were single turbopumps (one for fuel and one for oxidizer) driving four combustion chambers. The reason for four combustion chambers was to deal with acoustic problems inside the chamber. The F-1 had similar acoustic problems, but they were solved with baffles inside the chamber. The RD-170/171/180 are also multiple chambers driven by single fuel and oxidizer turbopumps.
Glushko's bureau did the N2O4-hydrazine engines for the UR-500 (Proton). The UR-700 was never built.
There were a lot of reasons for the failure of the N-1. Mishin's competence as an engineer had nothing to do with it. Korolov was successful because he had the ear of Kruschev and was good at motivating his people. When Kruschev was removed from power in 64, some would argue that the drive behind the N-1 went with him, though the last launch wouldn't be until late 1972. There were also the issue of multiple design bureaus getting money to build rockets capable of getting to the moon (Chelomei and Yangel are two that come to mind).
Korolov, like von Braun, made things happen more because of his personality and management skills than engineering prowess.
Jim Harford wrote an excellent book titled Korolov, which presents an excellent picture of his life from childhood to death. There's also quite a bit of information on what happened at his design bureau after his death.
You're right, it just does not burn, which is why the folks at Pratt & Whitney used tetra-ethyl-borane (teb) to light the engines. The low down on TEB is that it was originally a mining explosive that reacts very violently with oxygen. Start the fuel pump, squirt fuel in the combustion section and a squirt of TEB and you're on your way. Want afterburners? Another squirt of TEB to light those.
There's no way you'll ever convince the commercial operators to handle TEB. It's just too dangerous. Heck, NASA is trying to get rid of their nitrogen tetroxide - hydrazine based auxiliary power units because the fuels are so dangerous (toxic) to handle, and they're pros at handling that stuff. Too boot, they're willing to take a weight penalty to do it. But I digress.
I don't pretend to be an expert, but here is some information I've found in the past few minutes looking up info from common sources for propellant info. Most of the information can also be found on www.astronautix.com.
The density of LH2 is about 0.07 g/cc whereas kerosene averages around 0.8 g/cc. Liquid hydrogen has an energy density of 141 MJ/kg vs 46 MJ/kg for kerosene.
Hydrogen is usually commercially produced from steam reforming of natural gas, though processing of other hydrocarbons is possible. According to DOE, electrolosys is not likely to become the predominant means of producing large quantities of hydrogen.
And the vast majority of the weight in the External Tank is to hold the hydrogen because of it's low density, even when liquified.
The next logical extension is the extra volume required by an airplane to carry LH2 over kerosene. Is the weight penalty of larger tanks and extra drag from larger surface area worth the environmental benefits of using hydrogen. Not to mention that between SNECMA, GE AE, Pratt & Whitney, and Rolls Royce none of them produce gas turbines that can burn hydrogen.
Don't forget that the SR-71 was developed from a lot of work that went into designing a hydrogen fueled aircraft. When the design became too heavy and range estimates fell like a rock it was abandoned in favor of hydrocarbons.
I told GAC that it was a random algorithm, and it replied: "I think the answer to 'GAC is a random algorithm' is: True"
I think I'll stick with messing with LCS and Neural Nets.
No, you want to swallow the shock wave, as this is providing the necessary compression to run the engine. Look at it this way, you want maximum compression to get more thrust out of the engine (Hill & Petterson is an excellent reference). When the shock wave is expelled from operating at off nominal conditions, the compression falls sharply and the engine produces little thrust in comparison to it's brother sitting on the other side of the aircraft. NACA did a lot of research in the 1950's on controlling the shockwave produced by the diffuser. In addition to moving the diffuser for-aft you can also play with the fuel ratio to change the back pressure in the combution zone, and that can sometimes be enough to prevent the expulsion of the shock.