Quote from: Jim on 08/13/2009 01:02 pmQuote from: engstudent on 08/13/2009 12:49 pmHow do you calculate the escape velocity of a rocket and how is it dependent on the density of or choice of propellant?Escape velocity or exhaust velocity?Escape velocity - exhaust velocity is C = 9.8*Isp in the basic rocket equation relating deltaV, dry mass and propellant mass. I'm familiar with this [ dV = C*ln((M+P)/M) ] but not the relationship between the deltaV required of a vehicle depending on its... whats the word density impulse? How do you lower the dV required when C, exhaust velocity is fixed, or how do you compare the benefits of a propellant choice with slightly different C and grossly different density of P?

Quote from: engstudent on 08/13/2009 12:49 pmHow do you calculate the escape velocity of a rocket and how is it dependent on the density of or choice of propellant?Escape velocity or exhaust velocity?

How do you calculate the escape velocity of a rocket and how is it dependent on the density of or choice of propellant?

Quote from: engstudent on 08/13/2009 01:11 pmQuote from: Jim on 08/13/2009 01:02 pmQuote from: engstudent on 08/13/2009 12:49 pmHow do you calculate the escape velocity of a rocket and how is it dependent on the density of or choice of propellant?Escape velocity or exhaust velocity?I always thought is was 32.2 times ISP Danny DegerEscape velocity - exhaust velocity is C = 9.8*Isp in the basic rocket equation relating deltaV, dry mass and propellant mass. I'm familiar with this [ dV = C*ln((M+P)/M) ] but not the relationship between the deltaV required of a vehicle depending on its... whats the word density impulse? How do you lower the dV required when C, exhaust velocity is fixed, or how do you compare the benefits of a propellant choice with slightly different C and grossly different density of P?

Quote from: Jim on 08/13/2009 01:02 pmQuote from: engstudent on 08/13/2009 12:49 pmHow do you calculate the escape velocity of a rocket and how is it dependent on the density of or choice of propellant?Escape velocity or exhaust velocity?I always thought is was 32.2 times ISP Danny DegerEscape velocity - exhaust velocity is C = 9.8*Isp in the basic rocket equation relating deltaV, dry mass and propellant mass. I'm familiar with this [ dV = C*ln((M+P)/M) ] but not the relationship between the deltaV required of a vehicle depending on its... whats the word density impulse? How do you lower the dV required when C, exhaust velocity is fixed, or how do you compare the benefits of a propellant choice with slightly different C and grossly different density of P?

If I had a 25 tonnes fuel tank that is made to lift into orbit and picked up by my space ship how much would be tank and how much would be fuel?

Would a capsule in a retrograde orbit need extra shielding for a safe reentry??

When flying in a supersonic jet (or the shuttle), does the sound level in the cockpit (or crew module) change after the vehicle goes supersonic? I would guess that the answer is no since the crew is moving at the same speed as the source of the noise.

1) In space no one can hear you scream. But what if you stood in the exhaust of a rocket. Ignoring material considerations, what would you be likely to hear as you moved 'upsteam' along the exhaust closer and closer to the engine? Dull roar? High pitched whistle?2) If you were looking sideways through a hydrogen rocket exhaust in vacuum (at close range, and moving in the same direction) and there were no other bright objects around,a) would you still see the same faint blue glow and shock cones you see inside the atmosphere? Would sub-optimal altitude compensation produce any interesting effects?b) What would be the length of the vissible plume?

snip2a) By definition, no shock cones on a plume into vacuum.snip

Quote from: Antares on 10/08/2009 04:22 pmsnip2a) By definition, no shock cones on a plume into vacuum.snipThis is certainly true after the gasses have dispersed into the vacuum, but close to the nozzle there might be enough gas in the exhaust to form a visible shock wave.

Quote from: Danny Dot on 10/08/2009 04:33 pmQuote from: Antares on 10/08/2009 04:22 pmsnip2a) By definition, no shock cones on a plume into vacuum.snipThis is certainly true after the gasses have dispersed into the vacuum, but close to the nozzle there might be enough gas in the exhaust to form a visible shock wave. I don't get it. If there is no back pressure on the nozzle exit, what would the (supersonic) exhaust interact with? Indeed, there would have to be something with respect to what the flow would be supersonic in the first place, no?

Indeed, there would have to be something with respect to what the flow would be supersonic in the first place, no?