When do you usually stop using the term "altitude" and start using "distance from/to a planet"?Thank you.
Generally, "alitude" is used to identify an orbital path around a planet or moon and is repeating with each succeeding orbit while "distance" generally describes, for spacecraft anyway, how far it is from the planet/moon as it is approaching or departing.
Very basic question.In one message (http://forum.nasaspaceflight.com/index.php?topic=13206.msg526703#msg526703) Robotbeat stated that 195 second hover (a recent feat accomplished by Masten team) is enough for a trip from L2 to high Mars orbit. My question is how does one convert hover time to delta-v? Is it a matter of simple multiplying hover time by G? So you get:dV= t*G = 195s*9.81m/s^2 = 1912m/sIs this right? My second question is built on top of the first one. If this is correct, then one could calculate required hover time for a vehicle capable of reaching orbital velocity. I've assumed v0=9300m/s, so required hover time is 948s. Ignoring atmosphere drag, it is valid to say that if Masten vehicle would be able to achieve ~20% (195s/948s) of orbital velocity?
Very basic question.In one message (http://forum.nasaspaceflight.com/index.php?topic=13206.msg526703#msg526703) Robotbeat stated that 195 second hover (a recent feat accomplished by Masten team) is enough for a trip from L2 to high Mars orbit. My question is how does one convert hover time to delta-v? Is it a matter of simple multiplying hover time by G? So you get:dV= t*G = 195s*9.81m/s^2 = 1912m/sIs this right?
My second question is built on top of the first one. If this is correct, then one could calculate required hover time for a vehicle capable of reaching orbital velocity. I've assumed v0=9300m/s, so required hover time is 948s. Ignoring atmosphere drag, it is valid to say that if Masten vehicle would be able to achieve ~20% (195s/948s) of orbital velocity?
I'm guessing for stability, but are there other reasons? What would be the result in air pressure, if an SRB were placed between 2 fins?
Assuming their angle of incidence is zero, fins always move the center of pressure toward the fin. Assuming the center of pressure is aft of the center of gravity, they also act like dampers in a spring, mass, damper system.
Quote from: kyle_baron on 01/23/2010 09:56 pmI'm guessing for stability, but are there other reasons? What would be the result in air pressure, if an SRB were placed between 2 fins? Too many variables to answer the last question.
Quote from: Jim on 01/23/2010 10:04 pmQuote from: kyle_baron on 01/23/2010 09:56 pmI'm guessing for stability, but are there other reasons? What would be the result in air pressure, if an SRB were placed between 2 fins? Too many variables to answer the last question.Oh, I don't know about that. Let's think this thing through. The fin is parallel with the SRB (roughly speaking). And the SRB skirt would be at a 45 deg. angle to the fin (roughly speaking). Wouldn't a column of air comming straight down from the SRB get caught between the fin and skirt (45 deg. pointing down), and get thrusted beneath the base of the rocket? Might be another base heating variable.
Quote from: kyle_baron on 01/24/2010 02:45 pmQuote from: Jim on 01/23/2010 10:04 pmQuote from: kyle_baron on 01/23/2010 09:56 pmI'm guessing for stability, but are there other reasons? What would be the result in air pressure, if an SRB were placed between 2 fins? Too many variables to answer the last question.Oh, I don't know about that. Let's think this thing through. The fin is parallel with the SRB (roughly speaking). And the SRB skirt would be at a 45 deg. angle to the fin (roughly speaking). Wouldn't a column of air comming straight down from the SRB get caught between the fin and skirt (45 deg. pointing down), and get thrusted beneath the base of the rocket? Might be another base heating variable.What skirt? Whose says the skirt and fin are on the same level?
Fins could also be placed at the base of the rocket, unless you can think of a reason why they shouldn't be.
Quote from: kyle_baron on 01/24/2010 03:56 pmFins could also be placed at the base of the rocket, unless you can think of a reason why they shouldn't be. No need, only extra weight and drag.This is what is used. The scoops are on right and left of the base of the stage