Suborbital Flight

A lot of us here find ourselves flying long distance flights to pickup cargo and other products from various places around Vieneo, which requires the use of sub-orbital flight to save on fuel, since in space there is no air resistance slowing you down.

The only element which has an effect on your ship in orbit is the gravity generated by Vieneo. The most efficient way to get from point A to B in sub-orbit is to travel at high speeds which negate the pull of gravity from Vieneo, which in turn requires much less (if any) use of the thrusters to maintain altitude and no vertical speed.

You may have also found that getting up to sub-orbital altitudes can consume your fuel quite quickly, with an enormous amount of energy being needed to get you out of the atmosphere and to these high orbitally-stable speeds...

Before attempting this tutorial I am assuming:

• You are flying manually with full control of your spacecraft

• You are familiar with all of your spacecraft's cockpit instruments

• You know how to fly in the atmosphere and are comfortable with being in full control of your spacecraft

• You are flying a spacecraft with empty cargo bays (this makes a difference I will explain later)

• You are travelling at least 4000 km to your destination

• You realise this isn't the only way of doing things and you are of course as Rise allows you, able to find your own way of doing things if you wish

Liftoff!

Ok so now you need to lift off and I suggest you swing your spacecraft to face your intended direction of travel before accelerating forwards.

The Climb

Gently bring the thrust levers forward to full power and lift your nose gently to about 45 to 50 degrees of pitch, keep your velocity vector level with your watermark by using your thrusters as you do so. Once you reach the desired level of pitch, hold it there by adjusting to keep the velocity vector with your watermark, again with your thrusters. (You should only need short bursts to keep your velocity vector in the desired direction)

Keep this angle of pitch steady, feel free to make minor adjustments to your heading using small bank angles, five (5) degrees of bank should be enough.

Once you reach about 40-45 km in altitude, you need to start thrusting downwards whilst gently bringing your watermark level with the horizon, while allowing your velocity vector and VSI to continue to climb. While doing so, keep an eye on the amount of Gs you are pulling, you don't want to go breaking a wing, since you are still esentially in the atmosphere and your angle of attack still plays a big role.

Get some speed

The reason why I level out and use thrusters to maintain/increase the climb rate is simply maximising the efficiency of your fuel use, because now not only are you at this point increasing your climb, you are using your main engines to start to power you forwards to high speed before you reach your target altitude. Rather than using your main engines and a bit of thrusters to get to your target altitude and then starting your push forwards since you are at full throttle all the time.

I aim for a target altitude of 110 to 120 km as I find this the most comfortable for high speed long distance travel. You of course will find your own niche with which you are comfortable with. Assuming you are following my instructions, use your upwards thrusters to adjust your ascent rate to meet the target of 110 to 120 km altitude and settle to zero VSI while continuing to maintain your nose level with the horizon. You will have exited the atmosphere at about 70 km altitude and you don't have to worry so much about your Gs and angle of attack...

Continue to accelerate to about 5.630 km/s velocity which is indicated in the telemetry page of your left MFD. G/S (Ground Speed) indicated on your artificial horizon will not play any role in maintaining a stable orbit, but will indicate how quickly you are covering ground, this value will be different with each trip depending on how you are following Vieneo's spin on its axis..

Stabilize

Once you have reached about 5.630km/s you will notice that you no longer need your thrusters to keep your VS stable at 0 very much if at all. You will also notice in your contacts MFD that a new set of numbers have appeared at the bottom. These are basically the values relating to your current orbit, the value we are interested in however is the (e) value, in order for you to be in an almost perfect orbit without gaining or losing altitude, you need to keep this value as close to 0.0000000000000 as possible.

To keep your (e) stable first make sure your VSI indicates 0 and use your fore and aft fine tuning thrusters (button 3 and 4 on game controller) to make slight adjustments in your speed, monitor your (e) as you do so and continue adjustments until you are close to 0 as possible.

As you travel you may need to make VERY minor adjustments to your ascent descent rate with your thrusters, or similar to your velocity using your fore and aft thrusters to keep stable, but for the most part its hands off stick. You dont need to worry about your level of pitch until you are ready to descend to your target, it has no effect on your flight, but keep in mind when you make adjustments where your thrusters are and where they are pushing relative to your orientation!!! so it is best if you are level with the horizon when you make adjustments.

Tips for flying when loaded with cargo

• Do not climb at the 45 - 50 degree angle that I mentioned above, you will actually climb quicker if you maintain about 30 degrees of pitch.

• Your acceleration will be slower and every action you make will take time.. plan ahead of everything that you intend to do, and do everything slightly earlier than you would normally.

• Take extra care when leveling and continuing thrust at 40 to 45 km how I described, the G you may pull wil be alot harsher, so be gentle.

• Gravity will pull you harder, be prepared to hit those thrusters alot more to maintain your altitude whilst you are accelerating forwards to orbital speeds.

• You will burn alot more fuel when fully loaded, but using the technique I have described, just be happy that you could have burnt alot more uneccesarily. If you use aerobraking to slow down during re-entry you will cut your fuel costs even more. It would be well worth you learning aero braking if you have not done so already.

Final Thoughts

Well done, you are flying in a very fuel efficient and safe manner in sub-orbit to your destination!! good luck with the rest of your flight and enjoy the views!!

I hope this tutorial will give you some idea of the concepts of sub-orbital flying and the confidence to continue to develop perhaps your own way of doing it!

Thank you for reading and feel free to add any comments or ask any questions ingame.

--tezzac 18:10, 28 February 2007 (HKT)