Flight Question Landing the Delta-glider on a runway

[blixel]

I'm wondering if any of you guys bother landing the Delta-glider on a runway in an atmospheric environment such as Earth? (As opposed to using the hover engines to land on a pad - which to me, seems a heck of a lot easier.)

I've spent about 9 months with Orbiter so far, and I'm just now getting to the point where I'm successfully de-orbiting, re-entering Earth's atmosphere without overheating, and actually arriving on a target. The final hurdle is, of course, landing without crashing.

Landing on the moon is, in my opinion, not terribly difficult. (Once you get use to the rotation/translation system that is. Otherwise, it's very difficult at first.)

I've been doing this practice flight over and over again where I take off from KSC runway 33, bank sharply left to 220 degrees, climb to about 35km, coast along at about 2200 meters/second, intercept the VOR at Habana (Cuba), bank left to 150 degrees (because the ILS runway at Habana is 60, so I'm trying to catch the 60 degree VOR radial at a 90 degree angle (60+90=150) ... it may not be the best plan, but it's just what I've been doing) ... once I catch the 60 degree radial, I bank sharply left to intercept the radial.

All of that works perfectly to get me lined up to runway 60 at Habana.

The problem is in the last few dozen kilometers. I know how to read an ILS instrument ... if the bar is drifting right, it means you need to bank a little to the right to "catch" it, if it drifts left, you need to bank left. If the horizontal bar is low, it means you are too high, and if it's high, it means you are too low.

Anyway ... the saying is a picture is worth a thousand words and a video is worth a thousand pictures. (Something like that.)

So here is a 6 minute video of my 3 best landings so far. Each landing attempt is about 2 minutes long.

I just can't seem to nail it.

(This video is available at 720 resolution on youtube. It's probably better to watch it in a bigger window ... if you watch the video at the default small size, I doubt you'll be able to see the instrument data because it will be too compressed.)

I've tried using my CH Flight Yoke, but I actually find the keyboard to be better with Orbiter. The Flight Yoke is good for landing a light weight Cessna at 75MPH, but not a Delta-glider at 250-400 meters per second.

So back to my original question, I was just wondering if anyone even does a manual runway landing in Orbiter? Or do you just do VTOL landings on the pads, or use other spacecrafts that do the runway landings for you automatically?

 

[dgatsoulis]

Depends on the spacecraft. With the ones that do not have COG shift, i usually do normal, manual landings. With the ones that have, i do this:

 

[Mantis]

I typically always do runway landings on Earth and only do hover landings where no atmosphere exists to allow a runway landing. I find it much easier to line up with and land on a runway than on a small pad.

 

[Hielor]

Most people use runways, as far as I know.

Watching your video:
Attempt one:
0:35 - Why do you level off here? You're still above the glide slope according to the HSI.
1:09 - You can already see you're off course to the left here, don't wait so long to start correcting it.
1:30 - You're still *way* too far off to the left. Why did you never line back up with the runway?
1:46 - that's not the runway...

Attempt two:
2:57 - You're aiming too far short of the runway.
3:20 - Engines on and airbrakes too? Why?
3:29 - You waited far too long to pull up if you were trying to catch the ILS glideslope. If you're going to try to intercept the glideslope from above like that, you need to start pulling up as soon as the glideslope needle starts moving.
3:33 - The runway is down, not up...
3:40 - Where exactly are you going?
3:57 - That is far too steep of an angle for final approach. Plus, you've also let your speed drop a lot, which means you won't have the control forces needed to pull up.

Attempt three:
5:52 - You are pointing too high here, and you are already going too fast. Your airbrake should be out at this point, your engines shouldn't be on.

Analysis:
You have a tendency to come in too steep and too fast. If you want to use a stabilized airliner-like engines-on approach, you need a much shallower angle. If you want to use a shuttle-like gliding approach, you need to not have your engines on. Don't try to do a combination of the two, it won't work.

More importantly, ignore the ILS. Use some other MFD, or none at all. You're chasing the needles and trying too hard to follow the ILS and not actually looking at what's going on in front of the aircraft.

The DG gives you the wonderful flight path vector (the + in the circle) which tells you exactly where you're going to end up. Stick that on the end of the runway and keep it there, and that's where you'll end up.

I might post a video shortly, if it would help.

Cred sheet: IRL pilot, Orbiteer for 3+ years

 

[blixel]

Depends on the spacecraft. With the ones that do not have COG shift, i usually do normal, manual landings.

COG shift?

With the ones that have, i do this

Hmm... interesting video. I think that is kind of sort of the same thing I'm trying to do. Abstractly at least: Take off from a point on Earth, "jump" to high altitude, coast to the destination, and then get all the timing right so you come back down at hit your landing target in one shot. (My problem at the moment is that I can't land the damn Delta-glider to save my life.)

If I'm following your video correctly, you start out 19 kilometers from your destination, you climb to about 20 kilometers, arch over to cross the relatively short distance to the destination, then nose dive back in, level out at 1,000 kilometers and do a hover engine landing on top of (what appears to be) the Dubai tower. Is that right? Was that all done by hand? (I mean, without autopilots or scripting?)

Also, did your gear collapse on the runway?

I got the inspiration for these "jump from one Earth spaceport to another" by watching this video Tex put together. Coolest thing I've ever seen.

The way that guy nails that runway landing right on the center line at the end just totally blows my mind. Coming in out of the upper atmosphere with no remaining fuel. The timing on that whole thing is amazing.

---------- Post added at 09:23 AM ---------- Previous post was at 08:59 AM ----------

Most people use runways, as far as I know.

Watching your video:
Attempt one:
0:35 - Why do you level off here? You're still above the glide slope according to the HSI.
1:09 - You can already see you're off course to the left here, don't wait so long to start correcting it.
1:30 - You're still *way* too far off to the left. Why did you never line back up with the runway?
1:46 - that's not the runway...

hahah ... I know. But trust me, I am TRYING to hit the runway. It's just that I am doing so many things in those last few seconds that I can't get it all to come together.

In watching that replay, that was one thing I learned ... and I was even asking myself what must have been going through my head to distract me so much to prevent me from banking to the right. It is so obvious that I am off to the left, but I can only imagine I was focusing so much on something else that I couldn't be bothered to bank right.

Attempt two:
2:57 - You're aiming too far short of the runway.
3:20 - Engines on and airbrakes too? Why?

This was an experiment. I used the airbrake to slow myself down (to give myself more time to think) ... like using flaps on an airplane. But with the airbrakes extended, it seems like you need more engine thrust to keep from dropping like a rock.

3:29 - You waited far too long to pull up if you were trying to catch the ILS glideslope. If you're going to try to intercept the glideslope from above like that, you need to start pulling up as soon as the glideslope needle starts moving.
3:33 - The runway is down, not up...
3:40 - Where exactly are you going?
3:57 - That is far too steep of an angle for final approach. Plus, you've also let your speed drop a lot, which means you won't have the control forces needed to pull up.

I agree on all your points. Part of the problem too, I think, is the tunnel vision. I use to fly a Flight Sim with 3 monitors. It was so much easier to SEE my approaches. (And the graphics were a lot better which, for landing, helps. In my opinion.)

Attempt three:
5:52 - You are pointing too high here, and you are already going too fast. Your airbrake should be out at this point, your engines shouldn't be on.

Analysis:
You have a tendency to come in too steep and too fast. If you want to use a stabilized airliner-like engines-on approach, you need a much shallower angle. If you want to use a shuttle-like gliding approach, you need to not have your engines on. Don't try to do a combination of the two, it won't work.

Hmm... this is a really good point. I'm trying to figure out WHAT the Delta-glider can do. I think for now, I'm probably better off with the long, stable airliner-like approach ... just because it gives me time to think. That is ... if I can get the Delta-glider to slow down enough. The ILS instrument only picks up signal at 30 kilometers out. That sounds like a lot ... but when you're coming in at 300-400 meters per second, it's really not that much time to find the glideslope.

More importantly, ignore the ILS. Use some other MFD, or none at all. You're chasing the needles and trying too hard to follow the ILS and not actually looking at what's going on in front of the aircraft.

Hmm... interesting. I guess my Flight Sim habits are bad for Orbiter. I got to the point where I could hit the center line of a runway with the fog set to maximum to give almost zero visibility. So you had no choice but to watch the needles. You couldn't see the center line until you were on it.

The DG gives you the wonderful flight path vector (the + in the circle) which tells you exactly where you're going to end up. Stick that on the end of the runway and keep it there, and that's where you'll end up.

I'll give that a shot.

I might post a video shortly, if it would help.

Cool, yeah - definitely. If you have some video of your Delta-glider landings, I'd love to watch it.

 

[Nazban]

dgatsoulis where did you get the dubai addon??? i never knew there was one like that!!

 

[N_Molson]

I wish I had money... ;-)

I find runway landings easier and faster than a VTOL approach, provided you master the reentry... VTOL landings on Earth waste a lot of fuel IMHO...

 

[Urwumpe]

COG shift?

Trimming the space/aircraft by pumping fuel from forward to aft or back. Like on the SR-71 or the Concorde.

Also, did your gear collapse on the runway?

Too high vertical velocity on impact.

Remember: you land a spacecraft. Something with the aerodynamics of the Berlin wall and the agility of a supertanker. You need to line up as soon as possible, while also descending as steep as possible for remaining under control.

The simplest way is to come in at a very steep angle (about 20-30°) at the beginning of the runway running lights, without engines, and pull up to intercept the glide slope when it starts to appear on your HSI/ILS indicator (horizontal bar moves upward towards the center). This brings you into a shallow glide in front of the runway, during which you will quickly loose speed (Called preflare phase). once you are over the threshold, pull up more (flare) and try to land at a shallow angle and about 100 m/s - about 1.5° descent angle means 2.5 m/s vertical speed, something that your spacecraft can tolerate.

 

[N_Molson]

Don't be afraid to land fast. Stalling 10 meters over the runway is the worst thing to do. The SLF at KSC is wide and long enough to allow that

 

[Urwumpe]

Don't be afraid to land fast. Stalling 10 meters over the runway is the worst thing to do. The SLF at KSC is wide and long enough to allow that

Exactly. :lol:

 

[Grover]

In a glider, its best to keep the speed up, save the engines for the last kilometer and the number one rule for a runway landing: KEEP IT SMOOTH. Plan your trajectory ahead so you can avoid changing direction quickly.

As for hover landings, they may be easier in your opinion, but other people (those like me with plenty flight sim experience) prefer runways. And in any case, a hover landing will use more fuel

With a little practice youll be fine, the velocity ball is.your greatest tool. Put it about a quater of the way along the runway until youre 3km out (or sooner if yoh have little speed left) then SLOWLY move it towards the threshold. At 1km out you should be going straight for the threshold, with plenty of speed

As you come to land, keep the ball just below the horizon so you descend slowly, you font want to kill your crew seconds from the end of the mission, but dont take too long, or youll run out of runway or speed, either way youre dead

Good luck!

 

[dgatsoulis]

COG shift?

Center Of Gravity shift. The XR series enable you to "move" the ship's center of gravity, along it's longitudinal axis (z).

If I'm following your video correctly, you start out 19 kilometers from your destination, you climb to about 20 kilometers, arch over to cross the relatively short distance to the destination, then nose dive back in, level out at 1,000 kilometers and do a hover engine landing on top of (what appears to be) the Dubai tower. Is that right?)

Yes, that's pretty much it.
BTW, It doesn't "appear" do be the Dubai tower. It is. (Or at least the best 3d model that i could legally, get my hands on.) Having a working Lpad above the planet's surface, was a bit tricky, but Artlav's -now obsolete- "Meshland 1.92" addon, made it a simple matter of manipulating a couple of config files.
(FYI, i tried it on Orbiter 2010 and it still works!)

Was that all done by hand? (I mean, without autopilots or scripting?)

The whole flight was manual (15 euros joystick), up to the point that i made the "handbrake". In order to get the COG back to the centre, without having to actually press the buttons, (my hands,were already full), i used the XR2's built in, "ATTITUDE HOLD" autopilot, preset to zero pitch/zero bank. (Default settings).

Also, did your gear collapse on the runway?

No. It appears so, in the video, but it didn't.

I can send you the playback, if you want.

I made that vid, just by placing cameras on various points of my flight path, having a song that i liked on the Radio/MP3 MFD... and switced cameras, during a single flight. The onboard computer's call-outs, are not an effect. They are in realtime.

I got the inspiration for these "jump from one Earth spaceport to another" by watching this video Tex put together. Coolest thing I've ever seen.

:thumbup::thumbup::thumbup:
That was my inspiration too!
If you download the playback from OH,([ame="http://orbithangar.com/searchid.php?ID=3669"]KSC to Ascension Island in 1000 seconds (17 minute[/ame]), you will actually find two different scenarios!
One -insane, but doable- almost 20 minutes flight... and then another... 1000 seconds flight/time version! (I consider myself as one of the best XR2 pilot's over here, but to this day, haven't managed to beat that, eventhough, i got 10 seconds close to it.)

The way that guy nails that runway landing right on the center line at the end just totally blows my mind. Coming in out of the upper atmosphere with no remaining fuel. The timing on that whole thing is amazing.

Wait, 'till you see it. I promise you... you'll "poop monoliths" 2001 style!

 

[blixel]

More importantly, ignore the ILS. Use some other MFD, or none at all. You're chasing the needles and trying too hard to follow the ILS and not actually looking at what's going on in front of the aircraft.

The DG gives you the wonderful flight path vector (the + in the circle) which tells you exactly where you're going to end up. Stick that on the end of the runway and keep it there, and that's where you'll end up.

Wow - you are so right on both of these points. The ILS is semi-useful for lining up with the runway, but the horizontal bar is completely useless for these Delta-glider landings.

But what made All The Difference In The World was your second tip. Pointing the path vector at the near end of the runway and just using elevator trim to keep it there has made my landings significantly better!

I still need some work, but compare where I was just yesterday with this new set of landings. The difference is night and day.

 

[Hielor]

Wow - you are so right on both of these points. The ILS is semi-useful for lining up with the runway, but the horizontal bar is completely useless for these Delta-glider landings.

But what made All The Difference In The World was your second tip. Pointing the path vector at the near end of the runway and just using elevator trim to keep it there has made my landings significantly better!

I still need some work, but compare where I was just yesterday with this new set of landings. The difference is night and day.

Nice improvement. New comments:
Attempt One:
2:09- You don't need to turn the engines back up here. The DG won't stall until below 160m/s, so 195 at this point in the landing is fine.
2:30- Don't need to pull up so early-especially given that you're already a little fast, you should definitely still be pointing at the runway here.
2:48- Don't forget to flare just before touchdown--you kind of nosed into the runway there
Very good job on the lateral alignment, btw--big improvement.

Attempt Two:
Not bad. Definitely an improvement with the aiming and touchdown.

Attempt Three:
8:56 - At this point you have plenty of speed and altitude to make the runway, and should probably cut the engines.
10:18 - You kind of dived toward the runway there, and hit the nosewheel first. Partially this was due to it being a smaller runway and you carrying too much speed, so you dived down to try to get to the runway.

Overall:
Definitely an improvement. You're still carrying a lot more speed than you need to on the approach, which is what causes you to fly halfway down the runway before you land, but that's something that will come with practice, I think.

 

[blixel]

Definitely an improvement. You're still carrying a lot more speed than you need to on the approach, which is what causes you to fly halfway down the runway before you land, but that's something that will come with practice, I think.

Thanks again for the feedback. In reading what you said about carrying too much speed ... it occurred to me that I didn't use the Air brake on any of those attempts. I think I'll give that a shot ... maybe that will slow things down enough that I'll be able to work out the remaining issue of nosing the runway / floating too far down the runway and touching down at the half-way point instead of the near end of the runway. As you saw in the last attempt, I ran out of runway when I tried to land on the shorter KSC runway.

I might need to invest in a flight stick for atmospheric flight. I haven't really needed or wanted one up to this point since I've been doing almost everything in orbit. But now that I'm needing to land, the keyboard is starting to feel a bit limiting.

Anyway, thanks again for your input. It has been nagging in the back of my mind for several months now that I can do all these things in Orbiter ... except get back home safely.

With a bit more polish, I'll feel pretty confident about making the round trip.

 

[Hielor]

I might need to invest in a flight stick for atmospheric flight. I haven't really needed or wanted one up to this point since I've been doing almost everything in orbit. But now that I'm needing to land, the keyboard is starting to feel a bit limiting.

Does your yoke not work in Orbiter?

 

[blixel]

Does your yoke not work in Orbiter?

It works, but I think it's easier to use the keyboard.

I have to use the keyboard with or without the yoke. So by having the yoke mounted to my desk, I have to reach over it to press any keys I need to press.

Plus, I think the yoke has too much "play" (dead zone in the middle) to be practical for the Delta-glider. I've tried it ... it just doesn't feel right.

 

[Hielor]

It works, but I think it's easier to use the keyboard.

I have to use the keyboard with or without the yoke. So by having the yoke mounted to my desk, I have to reach over it to press any keys I need to press.

Plus, I think the yoke has too much "play" (dead zone in the middle) to be practical for the Delta-glider. I've tried it ... it just doesn't feel right.

Ah, makes sense.

 

[blixel]

I made one more video, but this time it's just 1 quick flight. In making the previous landing videos, it kind of piqued my interest in the camera modes and all of that kind of thing. (You see those videos other people make where they really show how cool Orbiter is through their mastery of camera positions and video editing.) I don't know how to do all that stuff ... but I took a shot at making a mini-film.

 

[ggrof]

After so many expert opinions here, there´s my humble opinion (and personal experience):
to land a delta glider is not a very difficult task, so don´t worry about that. It was also difficult to me in the first months wth orbiter so i trained so much lifting off the runway 33, reaching about 5000 k altitude, turning and landing the runway 15 in canaveral. I´ve done it SEVERAL times and i guess this is better than flying to habana for two reasons: first: you don´t waste much time, even accelerating time simulation; second: it´s easier once the deviation angle is not terribly out of path and good for training