The Space Shuttle sure comes down steep

[guitarxe]

While playing around with my SSTOs, I've noticed this clip that shows the Space Shuttle landing, and wow it sure comes down really steep, not at all at a glide like what I'm used to seeing most planes come down at.

Why was that? I know it wasn't supposed to really fly around like an airplane, but that seems a bit extreme. If it lacked "flyability" that much, how did they aim it at the runway from orbit?

[SargeRho]

It's a brick. It's very heavy, and has delta wings, so it needs to fly on a steep trajectory to remain fast enough to avoid stalling.

[K^2]

It looks steeper than it really is, because of the zoom lens, but yeah, it needs to be pretty steep. As Sarge said, it's a brick. It simply cannot match the glide slope of a typical airliner landing. To compensate, it uses its ludicrous approach speed to execute that final flare and kill all of the vertical speed just before it hits the ground. In short, if at first you don't succeed, landing Space Shuttles is not for you.

[mrfox]

The shuttle has more maneuverability from orbit then you might think. The wings on the shuttle are actually oversized, too large for what it actually needs. It can actually "glide" just over 1000 nautical miles off its orbital plane on re-entry. This was because of an added US air force requirement for the shuttle to do polar "once around" missions - which ended up never happening.

The "original" shuttle concept had even tinier wings, and would've come down even steeper.

The original reusable shuttle (small vehicle up top) with a manned, reusable flyback boooster (larger vehicle).

[worir4]

The shuttle has more maneuverability from orbit then you might think. The wings on the shuttle are actually oversized, too large for what it actually needs. It can actually "glide" just over 1000 nautical miles off its orbital plane on re-entry. This was because of an added US air force requirement for the shuttle to do polar "once around" missions - which ended up never happening.

The "original" shuttle concept had even tinier wings, and would've come down even steeper.

http://www.capcomespace.net/dossiers/espace_US/shuttle/1960-80/1970%20DC%203%20b.jpg

The original reusable shuttle (small vehicle up top) with a manned, reusable flyback boooster (larger vehicle).

That looks so awesome. They should just make one just because it looks so cool.

[DerekL1963]

The shuttle has more maneuverability from orbit then you might think. The wings on the shuttle are actually oversized, too large for what it actually needs. It can actually "glide" just over 1000 nautical miles off its orbital plane on re-entry. This was because of an added US air force requirement for the shuttle to do polar "once around" missions - which ended up never happening.

Actually, the cross-range capability of the Shuttle was used on practically every landing. Even though it was never used for once-around, it proved very handy indeed - here's a PDF from NASA showing the crossrange use for every flight through STS-88 in 1998. (Note that the cross-range of the "tiny wing/straight" version was somewhere around 250-300 miles.)

The "original" shuttle concept had even tinier wings, and would've come down even steeper.

Well, to start with - there is no such thing as the "original" shuttle design, there was a broad range of concepts examined at various stages, and then discarded for one reason or another. In particular, the "tiny wing" version you cite was on the very of being abandoned for two main reasons; First, it's low density made it very, very sensitive to cross winds. (In only about a quarter of the conditions the actual Shuttle landed in could this version have landed.) Second, the shock waves from those wings impacted directly on the fuselage. (Or, in other words, they directed a blowtorch of re-entry plasma onto the fuselage.)

The delta wing design with a long chine running forward to the nose emerged as a solution to this second problem. In addition it brought along solutions to other problems - the increased surface area lowered thermal protection requirements, and the lowered wing loading made it easier to fly. The delta wing also increased safety because the cross-range capability that came with it widened abort and landing windows. All the DoD did was push NASA in a direction it was already leaning in.

[mrfox]

Actually, the cross-range capability of the Shuttle was used on practically every landing. Even though it was never used for once-around, it proved very handy indeed - here's a PDF from NASA showing the crossrange use for every flight through STS-88 in 1998. (Note that the cross-range of the "tiny wing/straight" version was somewhere around 250-300 miles.)

Well, to start with - there is no such thing as the "original" shuttle design, there was a broad range of concepts examined at various stages, and then discarded for one reason or another. In particular, the "tiny wing" version you cite was on the very of being abandoned for two main reasons; First, it's low density made it very, very sensitive to cross winds. (In only about a quarter of the conditions the actual Shuttle landed in could this version have landed.) Second, the shock waves from those wings impacted directly on the fuselage. (Or, in other words, they directed a blowtorch of re-entry plasma onto the fuselage.)

The delta wing design with a long chine running forward to the nose emerged as a solution to this second problem. In addition it brought along solutions to other problems - the increased surface area lowered thermal protection requirements, and the lowered wing loading made it easier to fly. The delta wing also increased safety because the cross-range capability that came with it widened abort and landing windows. All the DoD did was push NASA in a direction it was already leaning in.

Interesting points. Thanks.

The DC3 would've had some cross-range capability - not as good as the STS, but certainly better than the capsules.

It was as close to an "official" concept as you can get at that point in history - it was Max Faget's personal design - and he was pretty much the king of design decisions at NASA prior to the shuttle project.

[Mazon Del]

"This isn't a plane, it's a flying brick on approach."

[Ten Key]

It certainly is a beautiful machine.

[Camacha]

In short, if at first you don't succeed, landing Space Shuttles is not for you.

The same applies to all other glider craft

[Jonboy]

All my shuttle replicas in 1.02 also require a pretty step decent, with a final pitch up to kill speed. Otherwise you'll drop straight down like a brick.

[prophet_01]

No idea how you do that pitch up trick. If I try it, I either stall or mess up the distance to the run way. So yeah... gliding is not for everyone

I go easy mode with lots of airbreaks and more lift than it needs.

[Rickenbacker]

It's not THAT bad. The shuttle had a glide ratio of about 4.5 to 1, half of a Cessna 172 (which has about a 9 to 1 glide ratio with the engine off). So it's steep, but you'd be surprised how scary an engine-off approach can be in any general aviation aircraft too .

[peadar1987]

No idea how you do that pitch up trick. If I try it, I either stall or mess up the distance to the run way. So yeah... gliding is not for everyone

I go easy mode with lots of airbreaks and more lift than it needs.

Well the runway at Edwards is 12.5km long, whereas the KSC runway is 2.5km long, it gives a much larger margin for error

[radonek]

The "original" shuttle concept had even tinier wings, and would've come down even steeper.

Umm, no. During descent there was a scary phase where it would go out of controll and fall until it gathered more speed, but its landing approach was supposedly safer. Straight wing can be much smaller because it has better low speed aerodynamics.

See http://history.nasa.gov/SP-4221/ch5.htm#212

[mrfox]

Umm, no. During descent there was a scary phase where it would go out of controll and fall until it gathered more speed, but its landing approach was supposedly safer. Straight wing can be much smaller because it has better low speed aerodynamics.

See http://history.nasa.gov/SP-4221/ch5.htm#212

Good article. If the shuttle had high aspect wings like the top down drawing there I would agree - the landing characteristics would be better but the controllability while stalled would be pretty bad. But most other concept art I've seen of the Faget shuttle had wings like the F104, which would make more sense for the reentry from an aerodynamics, heating, and structural point of view, at the expense of ease of landing - I'd assume that wouldve been the direction of compromise that wouldve been taken had the concept been pursued further.

But thanks for the link - its a very good read, especially regarding the reconnaissance mission specs for the air force shuttle - something that I had long suspected but could not find any literature about.

[Camacha]

It's not THAT bad. The shuttle had a glide ratio of about 4.5 to 1, half of a Cessna 172 (which has about a 9 to 1 glide ratio with the engine off). So it's steep, but you'd be surprised how scary an engine-off approach can be in any general aviation aircraft too .

It is really terrible. A normal craft will to between 1:15 and 1:35-ish, with gliders going all the way up to 1:60 nowadays. A Cessna is hardly a fair comparison, because those too are knows as bricks with wings. Even a 747, with four huge engines messing up your aerodynamics, will do 1:17 or something close to that. If you manage to lose the engines without messing up your controls or damaging anything else, you should improve your range dramatically.

1:4,5 is pretty much falling with some control.

[Beowolf]

A Cessna is hardly a fair comparison, because those too are knows as bricks with wings.

My Cherokee 140 was about the same. I imagine every plane with a fixed prop's going to make a pretty poor glider. Props were designed to efficiently disturb the airflow, after all.

[Camacha]

My Cherokee 140 was about the same. I imagine every plane with a fixed prop's going to make a pretty poor glider. Props were designed to efficiently disturb the airflow, after all.

Fixed propellers are a bad deal when you want to glide, that is for sure.

[K^2]

A large airliner on final can also be as bad as 4.5:1. Of course, that's largely due to flaps and less-than-optimal angle of attack. But that's why it has engines to compensate. So the actual slope it follows is much gentler.

And what the hell do you fly, Camacha, with a 35:1 glide? 10:1 is generally pretty good for something that isn't built to be a glider. A lot of general aviation and airliners (clean, cruise) fall near there. I can believe 15:1 for high-performance aircraft, but I've never seen anything close to 35:1 that isn't built to be a glider. In fact, just a few decades ago, that would have been considered a high quality sailplane. Of course, now with all the fancy materials, they're doing better than 70:1. You don't really have to land in one of these if you don't want to.