Flight Question Bouncing off of the atmosphere?!

[Hurricane]

This isn't atmospheric flight. This is space flight. You can't do it without MFDs. For example, I could do a looping or a corkscrew without instruments (in a sim for obvious reasons :shifty On the other hand, I could never land on the Moon or perform a Jupiter-to-Saturn slingshot without MFDs.

Actually, I can't perform the sling with MFDs either...:shifty:

MFDs are just instruments, to help you in your travels. It is true that there are autopilot MFDs that fly everything for you. But most MFDs don't. TransX, for example, just lets you (basically) input the maneuver(s) and then it calculates what your ship will be doing. Then you can go change the maneuver until eventually you'll see that the path takes you where you want to go. Sure, it tells you how and when to fire your engines, and you may consider it cheating. But even real astronauts have computers to help them.

Hey, real astronauts (used to) get flown into orbit by an autopilot. They don't fly the Space Shuttle during launch. A computer telling you when to burn is certainly not cheating compared to this... :lol:

Please notice that you are shifting my point of focus. I didn't say I DON'T use MFDs, I said I don't use add-ons. The reason is that Orbiter's default MFDs are powerful enough to do everything and yet simple and user friendly. Maybe it would be harder to set up slingshots, but it IS possible. Now this changes when it comes to reentries, because of the innaccuracies. I don't want to use external MFDs both because I don't feel like learning and because again, I want a MODERATE challenge (NOT blindfolded).
Anyway, this is getting off-topic! If I start to rise, pull UP. Right?

 

[Urwumpe]

You should still better use some selected add-ons there. The Orbiter MFDs don't give you all the information you need, especially for reentry, it misses the important variables completely. Reentry MFD was great to fill that gap, but I am not sure it works in 2010.

 

[Ark]

Just deploy the airbrakes.

 

[PeriapsisPrograde]

Even the shuttle has (had?) MFDs.

If you go lower tech in orbiter than NASA goes in real life... :2cents:

 

[Fabri91]

EDIT: something useful to say after all!
I agree, you should try at least some add-on MFDs, such as [ame="http://www.orbithangar.com/searchid.php?ID=2139"]Aerobrake MFD[/ame], since without these a precise reentry is impossible.

 

[Eli13]

Please notice that you are shifting my point of focus. I didn't say I DON'T use MFDs, I said I don't use add-ons. The reason is that Orbiter's default MFDs are powerful enough to do everything and yet simple and user friendly. Maybe it would be harder to set up slingshots, but it IS possible. Now this changes when it comes to reentries, because of the innaccuracies. I don't want to use external MFDs both because I don't feel like learning and because again, I want a MODERATE challenge (NOT blindfolded).
Anyway, this is getting off-topic! If I start to rise, pull UP. Right?

It is possible to re enter and land without MFD's.... If you like ending up in the ocean...

Look, I come from the atmospheric flight sim world too, but addon MFD's are among the best tools you can possibly use. Treat them right, and they'll get you where you need to go.

 

[Cras]

I have to admit that I am a bit confused by the atmospheric flight sim thing meaning a no-go on MFDs. I fly FSX all the time, and my primary aircraft I fly in FSX is (as I am sure it is now with many virtual aviators) is the PMDG NGX, and I cannot imagine flying it without its FMS or DUs. And those offer far more information and control over the aircraft than the MFDs that are being suggested do.

Glideslope MFD, Aerobrake MFD, these offer information. You still gotta fly the ship down to the grown. As far as I know, there still is no "Autoland" MFD available for Orbiter 2010p1, but if sans-MFD re-entry is the way you really want to go, then I recommend checking out the Antares, or another capsule type spacecraft, retro burn somewhere over Australia, and sit back as you crash into the ocean.

 

[PhantomCruiser]

So to sum up, if I start rising, what do I do?
~Thanks in advance.

Increase bank angle, this will alter your ground track a bit, but more importantly it will spoil your lift. As the ground track moves too far off target roll to the other direction.

 

[Hurricane]

EDIT: something useful to say after all!
I agree, you should try at least some add-on MFDs, such as Aerobrake MFD, since without these a precise reentry is impossible.

I WILL prove you wrong.

It is possible to re enter and land without MFD's.... If you like ending up in the ocean...

Look, I come from the atmospheric flight sim world too, but addon MFD's are among the best tools you can possibly use. Treat them right, and they'll get you where you need to go.

AND, treat the stock MFDs right, and you'll get to the same place without complications.

I have to admit that I am a bit confused by the atmospheric flight sim thing meaning a no-go on MFDs. I fly FSX all the time, and my primary aircraft I fly in FSX is (as I am sure it is now with many virtual aviators) is the PMDG NGX, and I cannot imagine flying it without its FMS or DUs. And those offer far more information and control over the aircraft than the MFDs that are being suggested do.

I don't refuse MFDs. Again. I refuse add-on MFDs. Just leave with it. I've learned my lesson, and now I'm going to do homework. WHEN I will manage to do this, I will post a tutorial. Then I'm going to try even more complicated stuff.

~Cheers, Oz. :tiphat:

 

[Arrowstar]

Or practice the famous "inverted reentry", a classic among bold DG-pilots

I love the inverted reentry. Managed just right, it can make getting down so much easier (if slightly more harrowing). :thumbup:

 

[n0mad23]

I understand Hurricane's position here - mostly. Buck Rogers-ing your way around in rockets is loads of fun, and my most thrilling OSFS times have been aerobraking and successfully landing in white-knuckle, seat of pants fashion, only using Surface MFD for information.

But I do think Hurricane's probably creating some self-imposed limitations that he'll probably want to get past at some point. For example, a "simple" trip to the Moon and subsequent return is totally possible using the built-in MFD's. But arriving at the Moon, exactly 7.5 km over the surface with 98% of your fuel remaining is really, really cool and virtually impossible without using TransX and/or IMFD.

It actually makes my head hurt contemplating white-knuckling a trip from Earth to Mars and then out to the moons of Jupiter, especially with maxed realism settings and limited fuel.

 

[Jarvitä]

So to sum up, if I start rising, what do I do?
~Thanks in advance. :tiphat:

Learn atmospheric physics and calculus, study orbiter's atmospheric model, get your calculator, some sheets of paper and a pencil.

Oh, you may want to pause orbiter, this could take a while.

 

[Eli13]

I WILL prove you wrong.
...
AND, treat the stock MFDs right, and you'll get to the same place without complications.

No, you won't. Not without a lot of luck. And buddy, luck is when hard work meets opportunity. And do you know what an opportunity is called in space? A WINDOW. And how are you supposed to find that nice little re-entry WINDOW without a tool telling you when and where it's gonna be?

Or you could take up Jarvitä's idea and make up for that lost opprotunity with hard work. And pause. A lot. Your choice. :shrug:

(Hey, just saying, some of these guys could sling around Jupiter and back before you figure out how to land on the Moon, I'd listen to them )

 

[fsci123]

Do yo bounce off the atmosphere and enter a less eccentric orbit... Or do you skip off and fly off into oblivion... It makes a difference in the way you may want to handle this...

 

[Hurricane]

No, you won't. Not without a lot of luck. And buddy, luck is when hard work meets opportunity.

Oh yes I will.

And do you know what an opportunity is called in space? A WINDOW.

A window! NOW I understand!

And how are you supposed to find that nice little re-entry WINDOW without a tool telling you when and where it's gonna be?

JUST BELIEVE! :thumbup:

Or you could take up Jarvitä's idea and make up for that lost opprotunity with hard work. And pause. A lot. Your choice. :shrug:

Hard work is goodie!

(Hey, just saying, some of these guys could sling around Jupiter and back before you figure out how to land on the Moon, I'd listen to them )

Good for them? Listen, I don't care what THEY can do and I CAN'T. Life is not a competition. And when we all go to NASA, everyone of us is going to have an advantage over the other at another field. Some will be astronauts, some will be flight engineers.

 

[Urwumpe]

Still, remember that you don't have the needed quantities displayed by any Orbiter MFD. You can estimate Delta-Azimuth, but not at the needed precision. you can only guesstimate the needed deceleration to hit a waypoint to your base. There is no AOA Hold function in orbiter, which is no huge problem (add-ons have it, often full trim up is enough), but missed badly when you fly manually.

Also, you have no indication of aerodynamic heat flux in vanilla Orbiter. It is only dynamic pressure multiplied by velocity, but you want to know it for telling how bad your reentry actually was.

 

[Hurricane]

Still, remember that you don't have the needed quantities displayed by any Orbiter MFD. You can estimate Delta-Azimuth, but not at the needed precision. you can only guesstimate the needed deceleration to hit a waypoint to your base. There is no AOA Hold function in orbiter, which is no huge problem (add-ons have it, often full trim up is enough), but missed badly when you fly manually.

Also, you have no indication of aerodynamic heat flux in vanilla Orbiter. It is only dynamic pressure multiplied by velocity, but you want to know it for telling how bad your reentry actually was.

I get you point. Still, though, I want to fly a reentry all by my own with no addons or autopilots.

 

[Tommy]

I'm going to assume that you are re-entering from LEO (not from the Moon or another planet - in which case the methods change at first).

I'm also going to be assuming that you are flying a DG, or one of the variants like an XR or DGIV. Capsules are a bit different.

First, I recommend reading this tutorial to get familiar with the basic concepts:
[ame="http://www.orbithangar.com/searchid.php?ID=3428"]Tutorial: Concepts for atmospheric reentry[/ame]

This isn't a "how to", it's a "why to". As a veteran of standard flight, you will have a few habits that you will need to break. In standard flight, the goal is "level flight", where both "force pairs" (gravity and lift, thrust and drag) are each balanced. This is pretty much never the case in Orbiter. Certainly not during re-entry - at least until the final approach. You won't have any thrust, but will want LOTS of drag. You also want to maintain a steady descent. In a DG (or variant) there are two main methods for doing this.

1. Low AoA Re-entry. This is pretty much the only choice with the stock DG. It can also be used with the add-ons like DGIV or XR series. De-orbit at least halfway around the Earth (more doesn't hurt - you'll have fairly low drag so you'll cover a lot of distance during the decelleration.) De-orbit burn should leave your PeA at about 40k - 50k. I like to use full "up" elevator trim since that adds a bit of drag - you may also want the airbrake engaged. By the time you are down to about 90k you want to be at a roll angle of about 80 degrees (either side). This will provide a bit of upward lift - you want your VS close to zero by 65k alt. Now watch the VACC as well as the VS. VACC will show you how your VS is going to change and help you anticipate those changes. Once you've leveled out keep the VACC small - never more than 2 or 3 m/s either way. If the VACC get's larger (absolute value) you will end up over-correcting. This is why being able to anticipate is so important - if you wait and react it will be too late.

Use bank to maintain the VACC low, and try for a VS of about -10m/s to -15m/s (especially in the add-ons which are "heat sensitive".) Increase the bank to lower the VACC and decrease bank to raise it. Every once in a while you will need a "roll reversal" to stay generally on course. First, lower the elevator trim to two "clicks" BELOW "zero", then roll the vessel to the other side, then increase the trim again. This will cause you make some gentle "S Turns", you'll need to practice the timing on those so that you end up where you want.

2. High AoA re-entry. This is easiest to perform if you are willing to use an Attitude Hold Autopilot like the XR series has, or P-104 on the DGIV. In the XR you can give the COG a couple clicks toward the rear, and use elevator trim to "fine tune" the AoA. In a DGIV you'll have to engage the AFCTRL on the 2-d panel, then switch to "Glass Cockpit mode" and press the little [ROT] button on the upper left of the HUD, and use the stick to try and hold the AoA.

De-orbit at least 18M from the base (farther is good - up to halfway around) and again establish a PeA of 45k to 50k. By the time you are down to about 100k you want to have an AoA (not pitch) of about 40 degrees. Again, get the VS close to zero by about 65k, and try to maintain a descent rate of about 80 m/s after that. You can use roll to maintain the VACC, but you can also use AoA (which lets you stay "on course", no S-Turns and Roll Reversals. To lower the VACC (real value - not absolute) INCREASE the AoA, and to raise the VACC LOWER the AoA. In other words, "Pitch Up to Go Down". If you need, add a bit of roll to adjust your course, but remember that if you increase the bank you need to decrease the AoA to maintain your descent rate.

It is possible to re-enter and land using only the "stock" MFD's, but it will take LOTS of practice to learn how fast you should be going at any given distance from base. If you are going slow, decrease the descent rate (increase VS), if you are too fast increase the descent rate (but be careful not to overheat in an XR or DGIV). It's best to de-orbit early, it's easy to increase your range but dangerous to "shorten" a re-entry. Even then, you'll "miss" once in a while and need the engines to make it to base. Add-ons like AerobrakeMFD will increase your accuracy and success rate.

As for another comment - no you CAN'T perform complex interplanetary flights with only "stock" MFD's. You can perform a simple interplanetary transfer - but it will be quite wasteful of your fuel. Slings, especially multiple slings, can't really be done unless you already have a valid flightplan. Even then, a Cassini type flight (which slings off of Venus twice in a row) simply can NOT be done without TransX or IMFD (or some VERY advanced math skills).

I'll give you the same advice I've given every other veteran of atmospheric flight simulators - Forget Everything You Know. Spaceflight - even the atmospheric portions like re-entry, are very different. Your experience with regular flight (simulated or real) will hamper your understanding. You will be trying to understand the new concepts while holding on to practices and theory that just don't apply in Orbiter.