Author Topic: ISRO & Reusability: Wings vs VTVL  (Read 18729 times)

Online sanman

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ISRO & Reusability: Wings vs VTVL
« on: 05/16/2016 02:46 pm »
ISRO has always tried to pitch cost savings as one of its over-arching goals, and had long ago envisioned pursuing reusability as a means towards this goal. Now that reusability by other space launch providers is demonstrating itself to be a prime cost-saver, ISRO is likely to face increasing expectations from the public in this regard.

http://www.asianscientist.com/2016/05/columns/isro-frugal-frontier/

When ISRO charted its path towards reusability long ago, the state-of-the-art in this field was the US Space Shuttle, a winged spacecraft. Likewise, ISRO selected a winged vehicle as its means of achieving reusability in launch vehicles. The upcoming RLV-TD testflight is intended to serve as a testbed demonstration and validation of the basic technologies ISRO intends to use for its future reusable space launch platform, the TSTO.

In the meantime, the US Space Shuttle program has been wound down in the US, and further iterations of this  winged launch vehicle are unlikely to be pursued. Among the newer generation of private space launch providers in the US, SpaceX and Blue Origin are leading the race into Vertical-Takeoff-Vertical-Landing (VTVL), which is now said to be the optimal way to do reusable spaceflight.

So is ISRO's future path to reusability now outmoded in the context of the new state-of-the art? Will ISRO still continue to pursue winged reusable spaceflight even when VTVL is advertising itself as inherently superior?

While it's understood that VTVL may be more technologically difficult than the older Shuttle-style horizontal winged landing, is it beyond ISRO's capabilities to move in this direction?
Would it be worth shifting towards VTVL at this juncture, since it may provide superior performance in the long run?
Having already invested so much planning into winged reusability, is it politically feasible to move in this direction?
Or will ISRO just naturally evolve towards VTVL after having gone through its winged exploratory phase?

How far away is India from having a reusable launch vehicle like the TSTO?
How much farther behind would it get if it shifted towards reusable VTVL?
Could some hybrid combination of the 2 approaches be useful?

Is it possible that reusability might even make its way into the ULV architecture, whether through wings or VTVL?

Offline cave_dweller

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #1 on: 05/16/2016 04:45 pm »

Wouldn't VTVL require carrying additional fuel to facilitate controlled landing? This approach would obviate the need for massive landing infrastructure (5KM long runway) etc. and also lend itself to being flexible to location.

Shuttle/Wing on the other hand would not require fuel as landing is achieved using areo-dynamic slowdown/drag (typical plane).

Also TSTO (two-stage to orbit) specifies plans for retrieving the upper-stages as well. By saving on fuel using wings for the recovery of the lower stages, wouldn't it leave room to carry fuel to recover the upper stage?

Offline cave_dweller

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #2 on: 05/16/2016 04:48 pm »
TSTO Profile



« Last Edit: 05/16/2016 04:52 pm by cave_dweller »

Online sanman

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #3 on: 05/17/2016 12:31 am »
The upper stage flight path sort of looks like VTVL, though I'm not sure if the parachute step disqualifies that. The closest thing it resembles is Soyuz capsule landings. I wonder if the parachute step would be dispensed with down the road, replacing the parachute mass with retroburn fuel mass. The diagram seems to imply that it will make an orbit before it de-orbits and returns to launch site.

But so I guess TSTO is intended to be a sort of combined hybrid approach, featuring both winged flyback and vertical landing.

While the winged flyback stage is meant to use semi-cryogenic kerolox and the upper stage is supposed to use hydrolox, I wonder if ISRO might ever consider developing a methalox engine and substituting that into the upper stage propulsion. Everyone on the forum has already mentioned the advantages of methalox over hydrolox, like the better propellant density, greater thrust, lower cost, relative safety and ease in handling, containment, etc.

ISRO seems to have already charted out its path on reusability, but I wonder how much room for flexibility there might be, as newer options and their advantages become known?
« Last Edit: 05/17/2016 01:07 am by sanman »

Offline Rocket Science

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #4 on: 05/17/2016 12:53 am »
Put some small wings on that second stage and land once around... :)
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Online sanman

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #5 on: 05/23/2016 09:03 pm »
Put some small wings on that second stage and land once around... :)

So the iterative progressive path I can imagine, is:

1) Shuttle-style spaceplane (12 tonnes) mounted on top of large SRB, like S-200 (parachute recoverable?)
2) SRB gets replaced with winged flyback booster powered by kerolox/semi-cryo engines
3) vertical launch stack is replaced with HOTOL
4) semi-cryo/kerolox engines are replaced with conventional turbojet + airbreathing scramjets (combined cycle)

Would steps 3 & 4 be steps forward or backwards - or sideways?

As far as bang-for-buck is concerned, then which direction is cheaper - kerolox or scramjet? Wings or VTVL?
Would HOTOL turbojet+scramjet facilitate "airline like" operations, as compared to kerolox and VTVL?

How do scramjets affect the "tyranny of the rocket equation"?
« Last Edit: 05/23/2016 09:24 pm by sanman »

Offline Rocket Science

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #6 on: 05/23/2016 09:24 pm »
1) We know from Shuttle/X-37B ops.
2) We know from X-15 re-usability.
3&4) Is basically SSTO which in all the years talked about has yet to fly including the interesting Skylon. Thus not flying would be a step backwards IMO...

Go with whats proven if you want to fly now...
« Last Edit: 05/23/2016 09:26 pm by Rocket Science »
"The laws of physics are unforgiving"
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Online sanman

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #7 on: 05/23/2016 09:27 pm »
1) We know from Shuttle/X-37B ops.
2) We know from X-15 re-usability.
3&4) Is basically SSTO which in all the years talked about has yet to fly including the interesting Skylon. Thus not flying would be a step backwards IMO...

Go with whats proven if you want to fly now...

Well, can TSTO be done with scramjets on the lower stage?
« Last Edit: 05/23/2016 09:36 pm by sanman »

Offline Rocket Science

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #8 on: 05/23/2016 09:35 pm »
1) We know from Shuttle/X-37B ops.
2) We know from X-15 re-usability.
3&4) Is basically SSTO which in all the years talked about has yet to fly including the interesting Skylon. Thus not flying would be a step backwards IMO...

Go with whats proven if you want to fly now...

Well, can TSTO be done with scramjets on the lower stage?
You would still need a rocket to get the scramjet up to speed so why bother thus Skylon does away with that... Just stick with a proven rocket design. Still waiting for the verdict on Falcon9R...
"The laws of physics are unforgiving"
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Offline redliox

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #9 on: 05/23/2016 09:40 pm »
I have to admit India has an interesting twist on winged spaceflight in essentially having the vehicle's nose separate.  I've never seen that suggested in a NASA configuration before, one with wings that is.  No need to incorporate a cargo bay or one winged vehicle piggybacking another.
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Online sanman

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #10 on: 05/23/2016 09:54 pm »
You would still need a rocket to get the scramjet up to speed so why bother thus Skylon does away with that... Just stick with a proven rocket design. Still waiting for the verdict on Falcon9R...

I thought the US has already flight-tested a vehicle with a combined-cycle engines.

How scalable are scramjets, for pushing against the rocket equation?


I have to admit India has an interesting twist on winged spaceflight in essentially having the vehicle's nose separate.  I've never seen that suggested in a NASA configuration before, one with wings that is.  No need to incorporate a cargo bay or one winged vehicle piggybacking another.

Well, the inter-stage gets lost as part of that - but hopefully it's not terribly expensive to replace.

Offline redliox

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #11 on: 05/23/2016 10:03 pm »
I have to admit India has an interesting twist on winged spaceflight in essentially having the vehicle's nose separate.  I've never seen that suggested in a NASA configuration before, one with wings that is.  No need to incorporate a cargo bay or one winged vehicle piggybacking another.

Well, the inter-stage gets lost as part of that - but hopefully it's not terribly expensive to replace.

It almost makes me think SpaceX and the STS teams got together and had a baby.
"Let the trails lead where they may, I will follow."
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Offline Rocket Science

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #12 on: 05/23/2016 10:04 pm »
You would still need a rocket to get the scramjet up to speed so why bother thus Skylon does away with that... Just stick with a proven rocket design. Still waiting for the verdict on Falcon9R...

I thought the US has already flight-tested a vehicle with a combined-cycle engines.

How scalable are scramjets, for pushing against the rocket equation?


I have to admit India has an interesting twist on winged spaceflight in essentially having the vehicle's nose separate.  I've never seen that suggested in a NASA configuration before, one with wings that is.  No need to incorporate a cargo bay or one winged vehicle piggybacking another.

Well, the inter-stage gets lost as part of that - but hopefully it's not terribly expensive to replace.
There was the X-30 that never was all we have now is the X-51

http://www.airforce-technology.com/projects/x51-wave-rider/

I still see it as potential yet expensive point to point technology, not for orbital flights... Other may differ in opinion but no one knows the future...
« Last Edit: 05/24/2016 12:25 am by Rocket Science »
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Online sanman

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #13 on: 05/23/2016 10:49 pm »
Well, according to this article, ISRO may even be looking at how to recover rocket stages the SpaceX way:

http://www.ndtv.com/india-news/isro-to-look-at-possibility-of-recovering-rocket-stage-1409084

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #14 on: 05/24/2016 01:32 am »
Well, according to this article, ISRO may even be looking at how to recover rocket stages the SpaceX way:

http://www.ndtv.com/india-news/isro-to-look-at-possibility-of-recovering-rocket-stage-1409084
They would be wise to see the "economics" of the SpaceX experiment first before deciding on an approach.
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Online sanman

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #15 on: 05/24/2016 02:53 am »
Some people elsewhere on the net are mentioning that the TSTO (pictured in the diagram above) would use not only the semi-cryo/kerolox rocket engines, but also a "DMRJ" (Dual Mode Ramjet). So that lower stage would indeed use its kerolox engines for the vertical takeoff, but as it accelerated to high enough mach number, those engines would cut off and the Dual Mode Ramjets (also on the lower stage) would kick in, accelerating to hypersonic speed. At some point stage separation occurs, and the hydrolox-powered upper stage would proceed to orbit.

So the Dual Mode Ramjets are combined-cycle  (ramjet/scramjet), able to work across a wider mach range. I presume this is what's being flight-tested next month, in June, aboard a sounding rocket.
« Last Edit: 05/24/2016 02:55 am by sanman »

Offline savuporo

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #16 on: 05/24/2016 07:32 am »
http://thewire.in/2016/05/23/not-just-the-rlv-td-isro-has-more-plans-for-slashing-launch-costs-37943/

Quote
In addition, ISRO was “very seriously” thinking of retrieving and reusing the core boosters of the GSLV and GSLV Mk-III in a SpaceX-like manner, according to him. The next generation Heavy Lift Launch Vehicle could also be designed with such reuse in mind.

The GSLV’s first stage, along with the four liquid-propellant strap-on boosters attached to it, account for almost three-fourths of the launch vehicle’s costs. “If we are able to recover and reuse [it], our reduction in cost will be maximum,” he said.
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Offline cave_dweller

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #17 on: 05/25/2016 05:00 am »
RLV-TD HEX was flown up to 70KM altitude which is about as near as possibly safe within Mesosphere (85 KM) -- which is about the altitude range limit for scramjets (because air density falls off significantly after Mesopause)

Seems to me Scramjets are more for assisted flight (to an extent) and to save on fuel. Is my understanding inaccurate?
« Last Edit: 05/25/2016 05:00 am by cave_dweller »

Online sanman

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #18 on: 05/25/2016 05:48 am »
RLV-TD HEX was flown up to 70KM altitude which is about as near as possibly safe within Mesosphere (85 KM) -- which is about the altitude range limit for scramjets (because air density falls off significantly after Mesopause)

Seems to me Scramjets are more for assisted flight (to an extent) and to save on fuel. Is my understanding inaccurate?

Yeah, that's my understanding too - the scramjets are to improve the mass fraction - and I guess maneuverability is important too, because Indian launch vehicles sometimes have to perform a "dog-leg" maneuver to avoid Sri Lankan airspace.



The scramjet test flight, ATV-D02 (Advanced Technology Vehicle - Development flight 2) is scheduled to happen in June, in a few weeks.

« Last Edit: 05/25/2016 06:00 am by sanman »

Offline vineethgk

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Re: ISRO & Reusability: Wings vs VTVL
« Reply #19 on: 05/25/2016 05:54 am »
ISRO to test rocket that takes its fuel from air

Quote
After successfully testing a technology demonstrator of a reusable launch vehicle, Indian Space Research Organisation (ISRO) is planning to test an air-breathing propulsion system, which aims to capitalise on the oxygen in the atmosphere instead of liquefied oxygen while in flight.
“The mission to test the technology would be launched either in the last week of June or early July from Satish Dhawan Space Centre at Sriharikota. The mission would be on a sounding rocket,” K. Sivan, Director of the Thiruvananthapuram-based Vikram Sarabhai Space Centre told The Hindu.
Quote
The new propulsion system, once mastered, would complement ISRO’s aim to develop a reusable launch vehicle, which would have longer flight duration. The system, involving the scramjet engine, would become crucial while sending up the spacecraft.
Quote
According to ISRO, the Dual Mode Ramjet (DMRJ), the ramjet-scramjet combination, “is currently under development, which will operate during the crucial Mach 3 to Mach 9 ascend flight of the launch vehicle.”

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