Britain's longest aircraft runway ?

[dr_gn]

So the Shuttle did have nose wheel steering for the vast majority of it operational career?

That's a bit different from what you wrote.

Eric Mc said:

The Shuttle didn't have nose wheel steering. It steered using differential braking on the main wheels (like on a Lancaster bomber). This often put undue strain on the brakes - especially in even modest crosswinds.

[Eric Mc]

dr_gn said:

So the Shuttle did have nose wheel steering for the vast majority of it operational career?

That's a bit different from what you wrote.

Eric Mc said:

The Shuttle didn't have nose wheel steering. It steered using differential braking on the main wheels (like on a Lancaster bomber). This often put undue strain on the brakes - especially in even modest crosswinds.

The point I was really trying to make (not very well obviously) was that it was initially assumed that differential steering would be good enough. It obviously wasn't.

And indeed, the wheel braking coupled with aerodynamic braking using the split rudder system was initially expected to be good enough to slow the Shuttle to a stop on the runway. They got that wrong too.

Therefore, after Challenger they had to radically re-think many of the basic assumptions about how to stop the Shuttle effectively in its landing run.

During the original design and specification phase of the Shuttle (1970 to 1972) nosewheel steering and parachute braking systems were discussed and considered but were rejected on cost and weight grounds. Following the Challenger accident, the ideas were revisited and incorporated.

Because the nosewheel steering system was a retrograde fit, it was never that effective and was only of marginal use. I'm pretty sure the crosswind landing limits remained totally unchanged after the nosewheel steering system was installed.

[Ginetta G15 Girl]

Eric Mc said:

Because the nosewheel steering system was a retrograde fit, it was never that effective and was only of marginal use. I'm pretty sure the crosswind landing limits remained totally unchanged after the nosewheel steering system was installed.

I doubt very much that the X-Wind limit was anything to do with whether the shuttle had nose-wheel steering, diff-braking or whatever, after all, in the landing phase the shuttle was just a big unpowered a/c.

In my experience you would be off the nosewheel steering by 50kts on T/O and only back on it during the landing roll out at relatively low speed. A similar situation was the case with those a/c using diff-braking. You would use the rudder to stay straight on landing until such time as you had no more aerodynamic control.

In other words, nosewheel steering / diff-braking is used at low speed (or during the taxy phase).


X-Wind limit is a function of directional stability/weathercocking tendency, CofG vs CofL, fin/rudder moment, but above all, rudder authority.

[anonymous-user]

Ginetta G15 Girl said:

In other words, nosewheel steering / diff-braking is used at low speed (or during the taxy phase).

Also the shuttle nose wheel didn't touch down until 20 seconds after main wheel touch down. The main wheel (differential) brakes didn't get used during the 20 seconds mentioned as they would result in high forces on the nose wheel as it hit the runway.

The only method of steering the shuttle during this 20 seconds was the rudder. The rudder wasn't as effective as a traditional rudder as it doubled as a speed brake so there was less deflection available when the speed brake was in use.

[Eric Mc]

Why did the tyre explode on STS-51D?

Extract from a report I've just found -

"However, because the nose gear had only a single strain control system, shuttle pilots were reluctant to use it at all, preferring differential braking with the main landing gear instead to control the shuttle's rollout down the runway in a crosswind situation. The strength of the crosswind on this landing led commander Karol Bobko to apply greater brake force than normal to the right main gear. Not surprisingly, the brakes on the right wheels heated to higher than expected temperatures.
But it wasn't the heat that caused the tire to fail. The largest factor in tire wear - and this tire's failure - was the surface of the Kennedy runway".

So - the report confirms that they WERE using the
braking to try and keep the Shuttle straight but that real culprit for the blow out was the rough texture of the runway.

[Ginetta G15 Girl]

Yes after the nose had been lowered and after they had lost aerodynamic control.

[Eric Mc]

Yes - not disputing that. But they were trying to steer using differential braking - which is what I originally said.

[anonymous-user]

Eric Mc said:

Yes - not disputing that. But they were trying to steer using differential braking - which is what I originally said.

Only late on in the landing rollout and at low speeds which is what she said.

[Eric Mc]

As I said. No dispute.

The more I learn about the Shuttle, the more ropy the whole device seems.

[mph1977]

Eric Mc said:

As I said. No dispute.

The more I learn about the Shuttle, the more ropy the whole device seems.

the idea was sold as this is the 'DC-3 moment' for spaceflight, when in fact it was at best this is Alcock and Brown's Vickers Vimy ...

[Eric Mc]

It could have been better. In all aeronautical design compromises have to be made. The problem with the Shuttle was that far too many compromises were made.

[MartG]

A bigger NASA budget during development may have seen a less compromised design as, for example, they would not have needed to alter it to gain USAF support

It was the USAF who requested a large landing cross-range capability, forcing the design to incorporate large wings - which when holed by tank insulation killed a crew

It was lack of development funds that prevented development of a liquid fuelled booster: instead they ended up with an external tank and solid boosters - which killed a crew

On the positive side it was the USAF who drove the large cargo bay ( sized to take a Keyhole spysat )

[Eric Mc]

Which allowed the ISS to be built - so not all bad.