Flight Question Unless there is a senario "Fly me to the moon" you just cannot fly into orbit?

[Roger55]

Unless there is a senario "Fly me to the moon" you just cannot fly into orbit?

In another scenario it appears you cannot do anything not allowed by that scenario. You cannot set up the moon as a target on the map in the Scram Jet scenario nor will you ever reach orbit in the DGS.

Is my statement correct?

 

[Mantis]

In another scenario it appears you cannot do anything not allowed by that scenario. You cannot set up the moon as a target on the map in the Scram Jet scenario nor will you ever reach orbit in the DGS.

Is my statement correct?

I'm not sure that I understand what you are saying. You should be able to reach the moon in any scenario as long as you wait for a valid launch window. There is a lot more to it than "setting a target" and launching though. The easiest way to reach the moon is to launch into low earth orbit during a good lunar launch window (meaning that the moon's orbit crosses or comes close too your launch location) and then utiize the Lunar Transfer MFD to get you there. You can also do it manually easily enough using the Transfer MFD.

 

[Roger55]

Then this phenomenon is very strange. In that very scenario whent you make the Moon the TGT on the map you get no orbit just a straight line south of the equator. Now the other problem may result from the fuel setting (unlimited) which seems to bring the DG down no matter how high you go on launch. I have a hard time flying the DG in atmosphere because it responds like a barn door on a turn (I'm an old flight simmer).

I just discovered that changing the fuel setting has no effect on the map TGT for the moon. No orbit just a straight line at about the tropic of Capricorn.

 

[orb]

In that very scenario whent you make the Moon the TGT on the map you get no orbit just a straight line south of the equator.

The solution for this is in "[MapMFD] Is this a bug with Map MFD in Orbiter 2010?" thread.

 

[Tommy]

Now the other problem may result from the fuel setting (unlimited) which seems to bring the DG down no matter how high you go on launch.

It's not the fuel setting that causes this. While it's true that the Shuttle can't reach orbit with "Unlimited Fuel" (it relies on mass reduction due to fuel usage), the DG and DGS can both easily make it into orbit with "Unlimited Fuel". The reason you are falling down is that you aren't going fast enough - you need to reach around 7.5 km/s to stay in low Earth orbit - it doesn't matter how high you launch (unless you actually escape Earth's gravity) if you don't have the horizontal velocity required.

Remember - it's centrifugal force that keeps a vessel in orbit, so you need enough velocity to generate that centrifugal force.

I'm not trying to be offensive, but you need to study up on spaceflight - it's very different from atmospheric flight. I suggest looking at the Tutorials section:

http://www.orbiter-forum.com/tutorials.php

The first one mentioned, "Go Play in Space" is the best place to start.

FWIW, the stock "DG-S Ready for Launch" scenario is less than one day from a lunar launch window, and right in the middle of a Mars launch window, IIRC.

 

[statickid]

Maybe someone already pointed this out but I'd wager a penny that you just need to set your map MFD to orbital plane rather than the ground tracking mode. This can be done in the options.

 

[Izack]

Remember - it's centrifugal force that keeps a vessel in orbit, so you need enough velocity to generate that centrifugal force.

Or momentum... :hide:

 

[Tommy]

Or momentum

Well, yes, you could say that - Centrifugal Force is a result of Momentum.

I'm certainly not the last authority on this, but my understanding is that Momentum is not a Force as much as it's the result of an energy state (which is the result of a Force). Momentum exists, unchanged, until a Force acts upon it, and it is the result of (kinetic) energy, but it is not "in and of itself" a Force. This is, of course, a very inadequate description. I personally find it easier to understand if viewed this way.

Gravity is a "Force", and it must be counteracted by a "Force". Engine thrust and aerodynamic lift are the "Forces" that do this in an aerodynamic flight regime. In orbit (outside any significant atmosphere) the force that counters Gravity is Centrifugal Force. When the two are balanced, a sort of stasis results, and the vessel will maintain a constant radius (given a spherical gravity source).

Momentum can overcome gravity - given enough velocity you can launch straight up and still leave the earth far behind - but gravity will reduce your momentum (at least until the gravity source is left far behind). Momentum itself cannot create the balance required for orbit (altitude stasis). Gravity is an "on-going" force, momentum is a "current" energy level. It's the "on-going" Force that Centrifugal Force provides that counteracts the "On-going " force of gravity. Admittedly, it's Momentum (in the correct direction, ie horizontal) that creates the Centrifugal Force.

Yes, this is nit-picking. It likely isn't "textbook" either. But comprehending the difference between Force and Energy is a key part of my understanding of Orbital Mechanics. It works for me - your mileage may vary!

 

[Loru]

Roger55: I suggest reading "Go Play in Space" first. Excelent for basic flight manuevers.

Can be found here: http://www.orbiter-forum.com/tutorials.php

 

[jedidia]

which seems to bring the DG down no matter how high you go on launch.

what goes up, must come down (up to the point where you exceed escape velocity, which you can do vertically with unlimited fuel, of course, but then it's not exactly an orbit anymore). Any orbit is achieved by building up HORIZONTAL velocity, not vertical. you only have to go up to get out of the atmosphere.

On the moon, where there is none, you can establish an orbit one meter above ground by going fast enough (unless you have ORULEX activated and a mountain gets in your way, of course). On earth that isn't possible because the atmosphere brakes you down, so you have to get to a certain altitude for that effect to become (almost) negligible, but it's still the horizontal velocity that makes you orbit, not your altitude. Good old Douglas Addams still described it best: "Falling and utterly failing to hit the ground". Because ground usually is pretty large, you have to go pretty fast to miss it...

The already numerous mentions of "Go play in space" are the best place to start getting the concepts.

 

[Xyon]

In another scenario it appears you cannot do anything not allowed by that scenario. You cannot set up the moon as a target on the map in the Scram Jet scenario nor will you ever reach orbit in the DGS.

Is my statement correct?

No, not at all. As others have mentioned, there are a lot of orbital mechanics involved which take some mastery, but the whole point (at least to me) of Orbiter is how open it is. Take any scenario, lift off, and go anywhere - nothing will stop you but your own skill.

Orbiter takes time, patience and practice to learn even the basics. I myself have been playing / piloting for three years, there or thereabouts, and I'm still learning new things - and I know there are many who have been learning longer and are still studying what can happen in various circumstances.

Orbiter is unlike other games. There is no linear progression along a defined track. Scenarios will not prevent you from doing anything - think of a scenario as a load list, all it really does is set the date, load the right solar system, populate it with vessels, and restore previously saved data if applicable. There are no rules in those files which would prevent you from doing anything. Indeed, Orbiter has no story line, no plot, no missions but the ones you make up yourself - it is a true sandbox, and this is one of its better qualities as far as I am concerned.

Learning the game is daunting, but the rewards are excellent. The first time you get to orbit yourself, the first docking, first successful reentry, transfer to the moon, to another planet, first lunar landing - all of these events will leave you with a tremendous sense of accomplishment when you realise that you had to work damned hard for each one of them. Orbiter is an open simulator - a physics engine with some graphics attached almost as an afterthought - it is yours to meld into the game or tool you want it to be, through learning how to play it, and eventually to modify it, to pull your own little universe in the direction you want it to go.

I will not repeat what the others have said, but I also agree with their points as well, especially Go Play In Space, which is apparently being updated for Orbiter 2010-P1 at the moment - the principles of space flight are identical however, so the reference text is still perfectly valid.

Edit: With that said, you can't launch from just anywhere and go to the moon, just like in real life, unless you have a LOT of dV and a lot of fuel, time and patience. Lunar missions, as all space flights do, require precise planning and very often can only be launched from specific sites, as well as at a certain time. For more information on that, look up the term "Launch Window" in your favourite search engine, or see the tutorials here once you've learned the basics.

 

[Roger55]

Let's see. Where are we.

The tutorial in the program shows that you launch when the moons orbit and the prospective orbit of the space craft almost coincide. Apparently you can't do that in any other scenario. I suppose to figure it out from Obit, right?

He (the tutorial) then takes off and turns at 90 degrees. The stick on the DG not only holds the bank but will keep banking till she rolls. At 3K feet flying level at about 30% power it's a very dicey operation to turn to 90 degrees you are usually over the Atlantic when this happens. Appropriate she flies worse than the SoSL on a full tank of gas

Then when you are set to take off, you power up and go to a 40-50 degree climb. But all the way you are fighting the stick to keep the heading and having to constantly fight the AG tendency to roll. (Yes, I tested the stick)

And that's the begining. More later if you want to hear it. If you don't, just say so. I'll go back to watching the Turorial and reread Go Play in Space.

Many of those threads show broken . And some lead to videos.

Two answer questions before I get then again.

1. I have dial up. 3.5kb/sec

2.I can't afford anything else.

 

[Wishbone]

I found flying with the stick somewhat more difficult than with the Numpad keys... YMMV...

EDIT: I'm on dialup too (at the moment 37.2kbit/s), so no videos for me, either.

 

[jedidia]

But all the way you are fighting the stick to keep the heading and having to constantly fight the AG tendency to roll.

Yes, that sounds pretty much like it... It's a rocket, not a plane, after all. Get her out of the atmosphere, and she'll dance for you (the DG most of all, it has totally overpowered RCS)! The heading doesn't have to be dead-on, you know, just get you into a few degrees of the transfer plane. Minor corrections on-orbit are no problem, big corrections are.

About those 90 degrees: 90 degrees are very good if you want just to practice how to get into orbit. Otherwise, you'll have to align your heading to your target's plane so you don't have to do large plane corrections once on Orbit (I usually have the plane alignement MFD open during launch and raise her by the seat of my pants... a thing you can comfortably do with the DG, but don't try it with vehicles with more realistic fuel margins...)

 

[Izack]

Yes, this is nit-picking. It likely isn't "textbook" either. But comprehending the difference between Force and Energy is a key part of my understanding of Orbital Mechanics. It works for me - your mileage may vary!

Well, I asked for it.

That's a more or less flawless approach to understanding orbital mechanics, and also a good portion of Newtonian mechanics in general.

 

[Roger55]

Part next since there are no objection

When she flattens out I go to that 34 K klicks I believe, which is I believe the ceiling of what I can reach, I go balistic and switch the controls (lin). Adding more energy just makes her go down faster. I let her reach apogee and then she just heals over and drops toward the Atlantic.

If I could get into orbit I figure that would be about 20% of the battle.

To answer another question I'm lucky if I can hold it to + or - 20 degrees of 90.

The orbit circle starts to widen, but I've never seen anything like the effect in the tutorial.

 

[Hielor]

When she flattens out I go to that 34 K klicks I believe, which is I believe the ceiling of what I can reach, I go balistic and switch the controls (lin). Adding more energy just makes her go down faster. I let her reach apogee and then she just heals over and drops toward the Atlantic.

The DG has no ceiling. Also, using "lin" (thrusters in linear translation mode) will result in you being unable to control the direction the DG is pointing--use "rot" (thrusters in rotational mode). And then go read the manual.

 

[Roger55]

Ok I was unclear. It's the highest I've been able to reach.

 

[Tommy]

I'm a little puzzled by the problem you have with the vessel rolling even with the stick centered - I don't have this problem myself. I would try disabling the stick and use the keyboard and see if this problem persists. It may be that you need to increase the "Dead Zone" a bit - if it's not large enough you will have real problems with rolling ever faster once you get into orbit. Even the best stick - PERFECTLY calibrated - will need some "Dead Space" with Orbiter. IIRC this can be adjusted on the Orbiter Launchpad.

I'll try to answer some of your questions, so here goes:

The tutorial in the program shows that you launch when the moons orbit and the prospective orbit of the space craft almost coincide. Apparently you can't do that in any other scenario. I suppose to figure it out from Obit, right?

This can be done from just about any scenario. You may have to wait for the correct time. The simple way to determine when to launch is to use MapMFD. You will need to target the Moon, and change the display from "Ground Track" to "Orbital Plane" (see the Orbiter Manual for details on doing this). You should now see the Moon's Orbital Plane displayed - it will look like a sine wave. If you engage some time accelleration, you will see this sine wave drift to the West. You will launch when this sine wave passes over your starting base - or gets as close to is as it will. For a Moon shot from Canaveral, you will launch when the northermost "peak" of the sine wave is just below Canaveral.

Now check MapMFD to see the Latitude of your vessel. It should be around 30 degrees if you are at Canaveral. Next, open OrbitMFD , make sure it's in equatorial frame, not ecliptic frame (again, see the manual for details) and target the Moon. Check it's Inc (inclination) - this will be just under 30 degrees.

When the Target's Inclination is less than or equal to your starting Latitude, you will launch at a 90 degree heading. This is the case with the Moon, or Mir.

When the Target's Inclination is greater than your Latitude, you will need to calculate a launch heading. I don't have the formula handy, but if you search the forum for "launch azimuth" or "launch heading" you will find it. To save you a bit of time, launch headings for the ISS from Canaveral are 42 degrees or 138 degrees. When you get a chance, download LaunchMFD - it will make those calculations for you and is VERY handy.

When she flattens out I go to that 34 K klicks I believe, which is I believe the ceiling of what I can reach,

How high you can go depends a lot on how fast you are going. The faster you go, the higher the DG can fly using it's wings for lift (like an airplane)

I go balistic and switch the controls (lin).

At around 35k you should still be using aero controls, not RCS. Also, lin, or Linear Translation mode, is for docking - you will be using rot (Rotation Mode) once you are above 50k or so.

Try this method - it's not the best for a DG, but it's a good "all around" ascent profile.

1. Once MapMFD shows the Moon's plane is in the right place, open OrbitMFD and SurfaceMFD. Engage full thrust and take off.

2. Once airborne, reduce throttle and watch the ACC (acceleration) shown in SurfaceMFD. Adjust the throttle to maintain a very small positive ACC. Trying to go too fast this low is very wasteful and makes controlling the DG much more difficult. You want to be going somewhere between 200m/s and 250m/s for now. Level out at somewhere between 1k and 2k altitude.

3. Turn to heading. Use small, gentle movements of the stick and avoid "over-controlling" (I think this, along with too high a speed at low altitude is causing much of your trouble staying on heading). Only when you are flying LEVEL (no roll) at the desired heading should you proceed to the next step.

4. Engage full throttle and pull back the stick to pitch up to about 70 degrees. When you get to 10k altitude engage about 3/4 downward trim (Insert key on keyboard). You want to gradually lower your pitch. You should be below 50 degrees pitch by 20k altitude, below 30 degrees by 30k altitude, and down to about 5 to 10 degrees by 45k. Fter the initial pitch-up, do NOT use the stick to control pitch - just elevator trim alone will work best.

5. At some point you may start to lose altitude. This will be because you are going to slow for your altitude and the wings can't generate enough lift. DO NOT use the stick to prevent this! Use full upward trim (Delete key) and let the DG sink down a bit. As your speed increases it will start to gain altitude again. Watch the VS (vertical speed) in SurfaceMFD, and try to keep it between 100m/s and 200m/s by using elevator trim ONLY.

6. Once you get near 7.5 km/s velocity, watch your ApA (Apoapsis Altitude - the highest point of your current trajectory) in OrbitMFD. Watch it fairly closely - it will climb very rapidly when you get up to speed. When the ApA is a bit over 200k shut off the engines. As you are coasting up, watch the ApA. If it's climbing, add some downward trim, if it's sinking add upward trim. You will probably find that one or two "clicks" below "nuetral" works. Once you are above 90k altitude you can stop watching it - it won't change much after that.

7. Continue coasting upward. At around 125k altitude, switch the controls to RCS ROT mode and you can engage the Prograde autopilot if you want. Now wait until ApT (in OrbitMFD is about 60, and engage the Prograde autopilot if you haven't already.

8. When Apt is around 30, engage about half throttle. Watch the PeA in Orbit MFD. Again, this number will increase slowly at first, the suddenly begin to increase rapidly. When that happens, throttle down some. When the PeA gets close to the ApA (both should be a bit over 200k, but anything over 190k will do for now) shut down the engines. Congratulations - you are in Orbit!

You may also want to check out this tutorial - [ame="http://www.orbithangar.com/searchid.php?ID=5024"]Interactive Surface to LEO lua Tutorial[/ame] - it's a small download (less than 4 kb) and will help you get into orbit. I haven't had a chance to see it yet, and it may use a different ascent profile, but it should be just fine.

If you don't have one, I suggest getting one of those USB memory sticks. That way you can use a high speed connection at a friend's house or the Public Library to download some add-ons that will make Orbiter more fun. Get OrbitSound, the DG-IV, UCGO, and UMMU ( I think UMMU is included with UCGO and/or the DGIV) from Dan's Orbiter page (see the quicklinks), and you may want to get LaunchMFD which will help you find the correct launch heading without having to do the math yourself.

I also recommend IMFD and LTMFD from Jormo once you are ready to try for the Moon or another Planet.

Hope this helps, I remember how frustrating it was to learn all this myself! I'll help when I can, but don't have internet at home so I only get online one or two days a week (usually Tuesday or Wednesday) so please be patient. Many other people here will help as well.

I will warn you that some people here can be a little rough on you if you don't seem to have read the manual, so try to learn the terminology and the basics first. The more specific your questions are (and the better you describe them) the easier it is to help.

 

[PhantomCruiser]

I go balistic and switch the controls (lin). Adding more energy just makes her go down faster

Ballistic, as in straight up?? Oh no, you don't want to do that, not in a stock DG... Right off the runway perhaps, just to show off for the ladies maybe, but not at altitude. To go ballistic will get you to space, but you may not be able to stay there...

When you get to around 30-35K in altitude, shallow out the climb to between 0 and 5 degrees (I just tried this to see if I could do it), I used the gimbled engines (over on the left of the console of the 2d panel). It took a bit of experimentation to get it right, and it still 'porpoised' on me a bit.

What happens is that you trade verticle speed (which you'll more than likely lose some of, but not to worry) for horizontal speed, which is what you need now to actually make orbit.

Ride it out and you'll be at orbital speed, watch your OrbitMFD, when your APA reaches 200Km (or whatever, but at least 200), cut your engine and coast to APA, turn prograde and burn to circularize your orbit and you'll have made it.

Keep trying, you'll get it. It's not rocket sci... oh wait... Never mind.