Indian Space Plane

[blinkythefish]

robbieduncan said:

Eric Mc said:

Aha - a more reasonable comment. It certainly does seem to share some attributes.


However, the purpose of this flight was to check for aerodynamic controllability at hypersonic speeds (over Mach 6) so I don't know at this stage what type of thermal protection system was fitted - if any.

http://arstechnica.com/science/2016/05/indias-shuttle-like-reusable-spaceplane-makes-its-first-test-flight/

"Indian officials said the vehicle's first test flight successfully demonstrated technologies such as autonomous navigation, guidance and control, as well as a reusable thermal protection system"

So it must have had some sort of thermal protection system fitted.

It doesn't look particularly large. Clearly not designed for human space flight. Which is fine. But unless that's a scale model is it even large enough to launch a reasonable satellite?

Article said the Technology Demonstrator was 6.5m long. It looks like the full design is bigger though.

[Eric Mc]

It's really a proof of concept test article. Both the US and the Soviets flew similar type test vehicles over 40 years ago. This was boosted to speed by a solid rocket launcher but the rocket wasn't big or powerful enough to get the craft up to orbital velocities. I'm sure they will have a go at an orbital; test as soon as they can get it onto a bigger rocket. This test flight glided down to a ditching in the Indian Ocean. Eventually, they will want it to land on a conventional runway - like the X-37 does.

[scubadude]

Thanks Eric, I thought it was interesting.

I'm surprised countries/companies are still looking at "space planes", I realise The Space Shuttle was politically and militarily shackled into a grand failure but IMO the overall compromises of a reusable plane for space flight are too many (until our materials science knowledge improves)
While its all very Gerry Anderson the combo of parachutes and retro rockets are so much lighter and more reliable they are hard to argue against.



FWIW- I have thoughts about India's use of money too but I would save them for the relevant sub-forum within PH, lets keep the "Science!" (Why does it have an Exclamation mark?) forum for Science.

[Eric Mc]

I think there is a place for spaceplanes - but not following the Space Shuttle concept.

Firstly, a future spaceplane would have to be smaller (maximum size one half of the Shuttle Orbiter).

Secondly, it would be positioned on top of any booster during launch, not on the side of the booster.

Thirdly - it need not have to be manned.

Fourthly - it may need to be protected within a jettisonable shroud - like the X-37. During ascent, the wings of a spaceplane produce asymetric aerodynamic loads on the stack which can place structural and payload limits on the mission. One of the reasons why the Shuttle stack rotated into the inverted "heads down" attitude during ascent was to try and alleviate some of the aerodynamic loads being generated by the wings. Placing the spaceplane within a shroud removes this problem.

Fifthly - I think future spaceplanes should have smaller wings in proportion to their body - or be lifting bodies with no wings at all. The large wings of the Shuttle came about because of the requirement to carry large and heavy DoD payloads into orbit, and to give the Orbiter the ability to alter its landing spot by 1,000 miles either side of its initial re-entry point (cross range). If you reduce the cross range requirement, you reduce the size of the wings.

In many ways, the X-37 is showing what can be done with winged re-entry and so far it seems to have performed its tasks (whatever they are) fairly succesfully

Regarding your comments on India's space expenditure - I am 100% in agreement with what you say. It is a topic worthy of discussion - but not on this thread which I wanted to keep about the spacecraft and related issues.

[Car Fan]

Very interesting, I don't know a great deal about space aircraft but I've just done some research and it looks impressive.

FWIW I am from India, I used to live there but am currently working in the UK as wages are better here, but I do intend to move back to India in the near future, and I'm very proud of my country's achievements in this field.

[Beati Dogu]

There's a video about it here:

https://www.youtube.com/watch?v=hW8877-A9YA


I wonder if the likes of SpaceX will ever use a similar idea as a 2nd stage for the falcon 9. Currently it is lost on every flight along along with the nose fairings, which cost a couple of million dollars alone.

Arianespace have a partially reusable rocket project called Adeline (ADvanced Expendable Launcher with INnovative engine Economy) which uses a similar idea, but only to bring back the main rocket engine.

https://www.youtube.com/watch?v=tV29pEvZvZw

[Foliage]

A contract has been given by nasa to a company to re-supply the ISS by space plane from 2019..

http://eandt.theiet.org/news/2016/jan/dream-chaser...

[Eric Mc]

NASA didn't really want to bother with Dream Chaser but were forced to reconsider their decision not to inject any further funds their way. NASA felt that Dream Chaser wasn't making enough progress. It seems now that NASA is only interested in an unmanned version for resupplying the ISS rather than a manned version.

It all got a bit legal and even had a knock on effect on the two capsule based systems NASA is continuing to support - Dragon and the CST.

https://en.wikipedia.org/wiki/Dream_Chaser

It's interesting that NASA are not mad keen on a winged spaceplane sitting exposed on the top of a rocket. It seems that they only will consider Dream Chaser if it can sit within a streamlined fairing - a bit like the X-37 does.

[robbieduncan]

How much extra fuel is burnt/wasted to push the aero load of the wings? Maybe not a lot but every kg of cargo lost makes the end-to-end economics less attractive. That said SpaceX maths shows that the cost of fuel is a very small component of the total so perhaps it's cheaper than losing the fairings every time?

[Eric Mc]

Having to alter ascent profiles and/or build a stronger structure to ensure the vehicle doesn't break up is what having exposed wings brings about.

Enclosing everything in an aerodynamic and lightweight shroud or fairing eliminates this particular problem.

[Flooble]

I see that the test didn't technically reach space (it reached 65km) so how much testing would the thermal protection system have received? Just the heating on the Mach 5 bit I guess?

At least the TPS didn't fall off during a subsonic hop, which is what happened to the shuttle (and yes, I know the famous case where loads of tiles fell off during the ferry on the back of the 747 involved lots of temporary ones that were only added for aerodynamics - but plenty of the real ones came off too)

An article I read said they did the whole thing for $14 million. That wouldn't even pay for Boeing to produce a powerpoint presentation ...

[Eric Mc]

The thermal protection fitted would have been sufficient to protect the craft at the speeds it was expected to achieve. Mach 5ish is roughly what the X-15 achieved in the 1960s - and on some of their flights they experienced structural damage due to aerodynamic heating.

[MartG]

Eric Mc said:

Having to alter ascent profiles and/or build a stronger structure to ensure the vehicle doesn't break up is what having exposed wings brings about.

Enclosing everything in an aerodynamic and lightweight shroud or fairing eliminates this particular problem.

Looking at the relative size of the vehicle's wings and the fins on the rocket, I get the feeling it wouldn't be aerodynamically stable - for stability you need the centre of mass to be ahead of the centre of pressure. Of course they could have been clever and tied the vehicle's control surfaces into the guidance system, a bit like the fly-by-wire systems used on modern unstable fighters, allowing it to fly without tumbling

BTW I heard somewhere that SpaceX are considering recovering their fairings at some time in the future - the condition of the debris that has washed up from past launches indicates that they were fine until they hit the water, so maybe some relatively small parachutes will do the job

[Eric Mc]

The Space Shuttle Orbiter was seriously unstable throughout most of its flight regime. Trying to make an aircraft that can fly under control at Mach 22 and also at 200 knots is not easy.

[Flooble]

Eric Mc said:

The Space Shuttle Orbiter was seriously unstable throughout most of its flight regime. Trying to make an aircraft that can fly under control at Mach 22 and also at 200 knots is not easy.

At least there is now fifty years of advances in software & hardware together with the knowledge from all the fly-by-wire aircraft such as the F-22, which are inherently unstable by design. Didn't they simulate the shuttle aerodynamics for pilot training by bolting bits to a regular aircraft until it could barely fly?

[RobDickinson]

For the cost ( what $14mil) this is seriously cool work.

I'm far from convinced a space plane is worth the effort but it might be a useful tool in some fast repeatable low mass launches

[hidetheelephants]

Leithen said:

I hadn't realised that the most recent X-37, launched in May 2015, is still up there....

What is it doing?

Much like submarines are described as being on missions to research cetacean life, X37 is probably counting penguins.

[Eric Mc]

Flooble said:

At least there is now fifty years of advances in software & hardware together with the knowledge from all the fly-by-wire aircraft such as the F-22, which are inherently unstable by design. Didn't they simulate the shuttle aerodynamics for pilot training by bolting bits to a regular aircraft until it could barely fly?

NASA used a converted Grumman Gulfstream II biz jet as a Shuttle simulator -



It was modified to simulate the characteristics of the Orbiter during landing and approach, but obviously couldn't simulate the flight behaviour at hypersonic or supersonic speeds.

Because of the problems of the movement of the centre of pressure during the re-entry, descent and landing phases, the Orbiter always had to carry some lead ballast. The amount carried on each mission depended on the payload requirements for the mission - but it did mean that on each flight into space, the Shuttle was hoisting dead weight into orbit.

[Flooble]

Eric Mc said:

...
Because of the problems of the movement of the centre of pressure during the re-entry, descent and landing phases, the Orbiter always had to carry some lead ballast. The amount carried on each mission depended on the payload requirements for the mission - but it did mean that on each flight into space, the Shuttle was hoisting dead weight into orbit.

Thanks for that Eric, it's like a walking encyclopedia :-)

That's brilliant, I had not heard about the ballast. Spend billions to shave a few ounces off various components here and there, then carry lead ballast. Couldn't make it up ...

[Eric Mc]

All spacecraft and aircraft are engineering compromises. The Shuttle was no different. However, as you say, having to carry dead weight on missions did negate one of the supposed selling points of the Shuttle system - economic transport of payload into orbit.