From Rise: The Vieneo Province
Atmospheric reentry is the process by which spacecraft from orbit of a planet or moon enter the atmosphere and reach the planetary surface intact. Typically this process requires special methods to protect against aerodynamic heating. Various advanced technologies have been developed to enable atmospheric reentry and flight at extreme velocities.
None of the E, W,or P-series aerospace vehicles are designed for true areobraking. In the case of MRO (Mars Reconnaissance Orbiter) It took 6 months to decelerate to orbital velocity.
- Thrust/Lift/Drag (Modified Aerobraking)
The ships in Rise use Iagreous fuel, For all practical purposes a pilot at orbital speed could use TVM set it to 0.5km/sec and let the ship use the engines to try and maintain that 0.5km/sec total speed all the way down to about 30km altitude and then transition over to normal flight.
TVM will get you down safe but it will literally fight lift, drag, gravity all the way down trying to get and maintain the set speed you put in.
Normal re-entry attitude
This entire discussion is based on the assumption that you are wings level, nose pointed in the direction of travel, and all of this is lined up with your desired destination.
Deciding When To Drop
A heavy ship takes more time and distance to decelerate. This entire lesson is based on an acceleration of 1.2 G in the vacuum of space.
First you must understand that the atmosphere has no measurable effect on your vessel until you descend below about 95-85km MSL assuming normal orbital speeds. Since you are not yet in the atmosphere you can not use the air to slow or generate lift.
If you are traveling at the orbital speed, or just under, and at 100-120 km altitude, you will start to using reverse thrust at around 1500-1300 km from your target. Use the up thrust (F9) to hold your ship above 100km till your ground speed is about 3km/sec.
With luck and or practice you will end up at about 2.5-3 km/sec as the target get to about 12-15 degrees nose down. Lower your nose to 15 degrees down. KEEP the engines in reverse but use the F8/F9 to help keep your direction of travel lined up with your nose. You will see some aerodynamic heating and plasma effects. As you generate more and more lift you will stop using the up and down thrust and start pitching the nose up and down to adjust your rate of descent.
REMEMBER it is NOT your FORWARD speed that will kill you IT IS your RATE OF DESCENT
The faster you change the outside air pressure the faster the drag changes. Higher drag, higher deceleration rate. 5km/sec at 100km altitude no problem. 5Km/sec at 70km you might as well drive in to a brick wall.
If you kept close to your ideal 15 degree down you will end up close to 30km and at 0.5 km a sec. If you made it down safely to where you are now flying like an airplane. WELL DONE and CONGRATULATIONS! You just completed your first safe operational reentry!! Go and get a drink and celebrate!!!
Points to Remember
- Do NOT fight the lift being placed on your vessel with pitch or thrusters you will risk over-stressing the air frame and losing bits from it, and causing injury or death. However if you need to help slow your descent rate, thrust downwards (F9) and use a little positive pitch to reduce your rate of descent.
- Do NOT roll inverted!
- If you are going to overshoot, no problem. Stop maneuvering and level out, ride the lift and begin your descent again when you are ready.
- Do NOT scramble to get on target in your first few attempts if you overshoot or come short SO WHAT?!?! The main thing is you need to be in one piece to be pleased with what you just acheived, you can work on getting on target with practice... safely!! Getting on target is not to promote expansion of your e-genitals!
- Your instruments are your friends, they will show you when danger is approaching, not the window.
- STAY CALM AND DO NOT PANIC!
Need further help just ask!