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#1 2016-04-09 18:37:59

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 16,173

VentureStar is it possible now

I just did a search for the topic venturestar but got only the places that we have talked about it....

http://newmars.com/forums/search.php?se … 057521&p=2

RobertDyck wrote:
Tom Kalbfus wrote:

SpaceX simply recognizes the fact that single-stage to orbit is not worth pursuing, and has instead pursued multiple reusable stages to orbit instead, We have spent billions on trying to achieve the former, and the former is not really achievable with chemical rockets, and we are unwilling to go nuclear!

We could do it with Timberwind. That was ground launch solid core nuclear thermal. They developed an upper stage, and I keep comparing the Timberwind upper stage to NERVA, but primary development was replacement for Titan. Nuclear activists got it cancelled.

But I would not say SSTO is not worth it. VentureStar would have worked. It pushed the edge of the envelope, but all spacecraft do. SpaceX chose to take an approach of reliable and inexpensive, then build on that. RP1/LOX is low performance, but cheap. It was used by the first stage of Saturn V and Atlas V.

VentureStar reduced weight with all composite propellant tanks, and extensive use of composites throughout. Corporate executives tried to gouge NASA in the usual way, but deliberately creating cost overruns, but NASA added a clause to the contract that said the contractor had to share the cost. Lockheed-Martin refused to comply with the contract they signed. Work halted for years while lawyers argued. They did propose going back to aluminum alloy, and not even aluminum-lithium like the Shuttle ET, they wanted the same aluminum alloy as the 1960s. The result was so heavy it couldn't launch. But if they stuck with the original design, it would have worked.

So what would it take to build it now....using the Space X model....not the Nasa contractor cost plus ......

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#2 2016-04-09 18:46:49

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 16,173

Re: VentureStar is it possible now

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

The VentureStar would have had a wingspan of 68 feet, a length of 127 feet, and would have weighed roughly 62,700 pounds.

Venturestar1.jpg

Shuttle size comparison....

VentureStar_Shuttle_Comparison.PNG

The design specifications called for the use of linear aerospike engines that maintain thrust efficiency at all altitudes

VentureStar by Lockheed Martin in Orbit - Computer Graphic


As indicated before X-33/VentureStar – What really happened
January 4, 2006 by Chris Bergin

Advances had been made with the thermal protection system (TPS) which doubled up as the aerodynamic shell of the vehicle.

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#3 2016-04-09 19:38:55

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 16,173

Re: VentureStar is it possible now

First thing that I see is seperating cargo from crew would be what I would change about the VentureStar design removing the cargo bay.

Next up is do we go with the composite tank or an alloy to reduct mass of launch.

Next is a review of the thermal protection tile as we do not want a standing army required to go over it after every launch.

Next up is selecting the size of crew that we want to lauch per mission in order to nail down its role for cost reduction for manned launches.

We also know that using composites do work for many things and will need to review what locations thst are to get them.

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#4 2016-04-09 22:14:49

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 5,794
Website

Re: VentureStar is it possible now

Shuttle's thermal protection system was vulnerable because the external tank shed chunks of ice. Or worse, chunks of foam with humidity from the Florida coast condensed and frozen within the foam. The foam acted as fibre reinforcement within ice matrix. When ice or ice soaked foam broke off and hit tiles, they broke. No external tank, no ice. Shuttle replaced white tiles with thermal blankets, which eliminated tile loss due to vibration from SRBs. Thermal blankets proved to be less expensive to manufacture, never shook off, never broke or tore off from ice strikes, and rarely got damage from ice strikes. Which raises another point: no SRB means much smoother ride, far less damage due to vibration. Initial thermal blankets were felt, but very quickly were replaced by "Advanced Flexible Reusable Surface Insulation" (AFRSI), which were quilts made of the same 99+% pure silica as tiles, but spun as threads and wove to form fabric. The fabric that faced Shuttle's aluminum skin was normal fibreglass, but outside fabric was highly pure silica. Batting inside the quilt was also highly pure silica fibre.

My point is that with no external tank or SRBs, this new vehicle could use the same thermal protection system as Shuttle at end of life.

A couple improvements: replace the quartz windows with ALON. That material is already used on ISS for windows of the cupola. It won't pit due to micrometeoroid strikes, so no need to hand grind the windshield between each flight. Based on temperature ratings that GW Johnson gave us for the Shuttle windshield, ALON can handle even more heat. Temperature isn't my concern, eliminating hand processing between flights is.

The other improvement is the next generation thermal blanket. Developed by NASA's Ames Research Center, the same guys who developed AFRSI. The new one is DurAFRSI. It uses ceramic fibre instead of silica, able to handle slightly more heat. Not as much heat as black tiles, but slightly more than AFRSI. Most importantly, it has Inconel 617 foil skin. The metal foil skin is smooth, improving aerodynamics. It was never installed on Shuttle because NASA couldn't justify expense of replacing thermal blankets. Vulnerability was primarily black tiles, with the worry of Reinforced Carbon-Carbon leading edges after the Colombia accident.

RCC was strong enough that it didn't need any backing material. Wing leading edges were hollow, but no metal inside. They were mounted as solid components. Nose cap was also RCC. But black tiles were white silica foam coated with a black glaze as thin as a coat of paint. They were densified on the under side where they were glued to a layer of felt. They required felt between the aluminum alloy skin and tile because tiles would expand as they got hot. The felt was flexible, it could move a little. If tiles were bonded directly to aluminum skin, thermal expansion would break the glue, causing them to fall off. But silica foam tiles definitely require a separate aircraft shell. They're too weak/fragile to be the shell themselves.

One small change the Russians made on their space shuttles. Their first orbiter was named Buran, but the program to develop the orbiters was called Burya. Do I call them "Burya shuttles"? That change was to orient tiles at 45° to air flow. They claimed this resulted in less hot gas infiltration beneath tiles.

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#5 2016-04-10 06:43:33

Tom Kalbfus
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Registered: 2006-08-16
Posts: 4,401

Re: VentureStar is it possible now

I think SpaceX went the multi-stage route, because it would have been easier to do. VentureStar required some extreme engineering to make it work, and required the participation of the US government. If it were obvious that it would lead to a single stage vehicle, a private company could raise the funds for it, and it would be profitable to launch, instead of requiring a continuous government subsidy as the shuttle has. It is probably cheaper to make the bottom stage of a rocket reusable, rather than trying to build an entire single stage to orbit vehicle in one fell swoop! Anyway, if you have a four stage rocket with four reusable stages, you have four reusable vehicles that stack on top of one another. Each stage need not be as delicate or as fragile as a single stage to orbit reusable vehicle. You don't have to economize on weight as much, and you can design it for multiple configurations and payloads, using 3 stages for smaller payloads and maybe 5 stages for the larger ones.

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#6 2016-04-10 08:54:59

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 16,173

Re: VentureStar is it possible now

With each stage requiring the protection and or compensation for re-entry it will have a mass penaly for each that is used that translate back towards the first stage not having the performance to boost the next stage to the correct location. In order to keep the payload that is wanted the stage proceeding it and the next so on down towards the first must have a boost in performance and mass moving capability.

Not to get to far adrift of topic but here is the links
https://en.wikipedia.org/wiki/SpaceX_re … nt_program
http://aviationweek.com/blog/nasa-cnes- … n-9-rocket

In theory, the SpaceX Falcon 9 v1.1 booster can be reused more than three-dozen times.

That's because the rocket's LOX/Kerosene Merlin 1D engine -- nine of which power its first stage -- has a cycle of 40, but “We don't know how many times we can fly the first stage.

Falcon 9 is already the lowest-cost rocket on the commercial market today. Able to throw 4,850 kg of payload to supersynchronous transfer orbit at roughly $60 million per launch, it bests even the Chinese Long March 3B at $70 million a pop.

Noting that the cost of fuel, oxygen and other expendable liquids in the rocket amounts to just 0.3% of the cost of a Falcon 9 mission.

One of the most challenging aspects of reusability, he said, is the weight penalty added by hardware and propellant. He says the latter means reserving 30% of first-stage fuel in order to return a booster to the launch site.

“You end up designing much larger vehicles, with landing gear, with legs or wings, so it's heavier and you need more propulsion, at least 25-30% more propulsion on the stage,”


second stage reuse plans
http://space.stackexchange.com/question … cond-stage

http://www.popularmechanics.com/space/r … s-6653023/

The key, at least for the first stage, is the difference in speed. "It really comes down to what the staging Mach number would be," Musk says, referencing the speed the rocket would be traveling at separation. "For an expendable Falcon 9 rocket, that is around Mach 10. For a reusable Falcon 9, it is around Mach 6, depending on the mission." For the reusable version, the rocket must be traveling at a slower speed at separation because the burn must end early, preserving enough propellant to let the rocket fly back and land vertically. This also makes recovery easier because entry velocities are slower. "The payload penalty for full and fast reusability versus an expendable version is roughly 40 percent," Musk says. "[But] propellant cost is less than 0.4 percent of the total flight cost.

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#7 2016-04-10 09:38:31

Tom Kalbfus
Banned
Registered: 2006-08-16
Posts: 4,401

Re: VentureStar is it possible now

SpaceNut wrote:

With each stage requiring the protection and or compensation for re-entry it will have a mass penaly for each that is used that translate back towards the first stage not having the performance to boost the next stage to the correct location. In order to keep the payload that is wanted the stage proceeding it and the next so on down towards the first must have a boost in performance and mass moving capability.

Not to get to far adrift of topic but here is the links
https://en.wikipedia.org/wiki/SpaceX_re … nt_program
http://aviationweek.com/blog/nasa-cnes- … n-9-rocket

In theory, the SpaceX Falcon 9 v1.1 booster can be reused more than three-dozen times.

That's because the rocket's LOX/Kerosene Merlin 1D engine -- nine of which power its first stage -- has a cycle of 40, but “We don't know how many times we can fly the first stage.

Falcon 9 is already the lowest-cost rocket on the commercial market today. Able to throw 4,850 kg of payload to supersynchronous transfer orbit at roughly $60 million per launch, it bests even the Chinese Long March 3B at $70 million a pop.

Noting that the cost of fuel, oxygen and other expendable liquids in the rocket amounts to just 0.3% of the cost of a Falcon 9 mission.

One of the most challenging aspects of reusability, he said, is the weight penalty added by hardware and propellant. He says the latter means reserving 30% of first-stage fuel in order to return a booster to the launch site.

“You end up designing much larger vehicles, with landing gear, with legs or wings, so it's heavier and you need more propulsion, at least 25-30% more propulsion on the stage,”


second stage reuse plans
http://space.stackexchange.com/question … cond-stage

http://www.popularmechanics.com/space/r … s-6653023/

The key, at least for the first stage, is the difference in speed. "It really comes down to what the staging Mach number would be," Musk says, referencing the speed the rocket would be traveling at separation. "For an expendable Falcon 9 rocket, that is around Mach 10. For a reusable Falcon 9, it is around Mach 6, depending on the mission." For the reusable version, the rocket must be traveling at a slower speed at separation because the burn must end early, preserving enough propellant to let the rocket fly back and land vertically. This also makes recovery easier because entry velocities are slower. "The payload penalty for full and fast reusability versus an expendable version is roughly 40 percent," Musk says. "[But] propellant cost is less than 0.4 percent of the total flight cost.

So the solution is to make the stages 40% larger so you can preserve the payload lift capability, this might make the stages cost 40% more to build, but then if you use it twice, you would have to build a booster that is 100% larger to lift the same amount of payload in one launch that launching two successive launches with the same rocket would accomplish. 40% vs 100%. I think 40% is better.

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#8 2016-04-10 15:18:34

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 16,173

Re: VentureStar is it possible now

The mass penalty is different for each stage... take any capsule in orbit what you add to bring it back down is a heatshield, parachutes and fuel for the deburn...but a third stage does not normally have these and because that stage is larger so will be the parachute plus heatshield and protection system for the stages sides then the fuel for orbital deburn if it is brought that far before releasing the payload... but here is the twist when it comes to the landing the fuel is not the same as for the first stage as the speed is different for the land based or floating platform of a third stage. The second stage would function much like the third stage and the mass penalty would be even higher to make it still for recoverability....

So once we look at the totals it might be better to go with a single stage to reduce the penalties but then again if its cost rise to a point that its cheaper to buy a regular rocket what would be the point of reusuability since the important one is cost per flight....

So lets see if we can get back to VentureStar as I will post the above comments to the space X topic...

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#9 2016-04-10 15:31:18

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 16,173

Re: VentureStar is it possible now

So maybe a total reuseable single stage to orbit might be possible but then a again a complete expendable single stage could be a better cost than the reuseable for manned flights.

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#10 2016-04-10 19:39:23

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 16,173

Re: VentureStar is it possible now

Here is another article along the same lines....

XS-1 program to ease access to space enters Phase 2

xs-1-fully-reusable-unmanned-booster-vehicle-suborbital-altitude-low-earth-orbit-leo-lg.jpg

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#11 2016-04-16 19:29:29

kbd512
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Registered: 2015-01-02
Posts: 2,959

Re: VentureStar is it possible now

Tom,

There's not really any economy to be had using 3+ stage vehicles unless you're going beyond LEO.  The engineering involved only gets more complicated with 3+ stage launch vehicles.  The Saturn V engineers can attest to that fact.

SpaceNut,

SSTO's are now technically feasible with robotically manufactured lightweight composite tanks, full-flow staged combustion LOX/LH2 engines, and lightweight disposable ablators.  I would skip reusable insulation altogether and figure out how to use fabrics to protect the vehicle upon reentry.  The fabric covering would be replaced after every mission.  We'd need some system to fasten the fabric to the skin of the vehicle that permitted quick and easy removal.  In the end, this method of thermal protection will be cheaper and easier to maintain.

There's no such thing as reusability after reentry.

Rob,

Forget about using STS thermal protection.  It's old, expensive tech.  It's functional, but that's as far as its merit takes it.  Amazing performance for 1970's technology, but we can do it better / faster / cheaper with fabrics.  Control surfaces can use RCC.  I don't see any reason to go back to using tiles, though.

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#12 2016-04-17 08:46:47

Tom Kalbfus
Banned
Registered: 2006-08-16
Posts: 4,401

Re: VentureStar is it possible now

kbd512 wrote:

Tom,

There's not really any economy to be had using 3+ stage vehicles unless you're going beyond LEO.  The engineering involved only gets more complicated with 3+ stage launch vehicles.  The Saturn V engineers can attest to that fact.

Well of course we're going beyond LEO, this is the Mars society isn't it? In a 3+ stage vehicle, the bottom stages are the most expensive. It might be possible to use the top stages if they use something like a nuclear thermal drive once they achieve orbit, the 3+ stages are for going elsewhere other than low Earth orbit. Now a nuclear, or plasma drive might be able to take you from low Earth orbit to low Mars orbit and then back again with a low thrust high impulse option, and such stages might even be returned to Earth and refurbished after a number of uses in orbit, and then launched again on top of another 3+ stage rocket back into orbit.

kbd512 wrote:

SpaceNut,

SSTO's are now technically feasible with robotically manufactured lightweight composite tanks, full-flow staged combustion LOX/LH2 engines, and lightweight disposable ablators.  I would skip reusable insulation altogether and figure out how to use fabrics to protect the vehicle upon reentry.  The fabric covering would be replaced after every mission.  We'd need some system to fasten the fabric to the skin of the vehicle that permitted quick and easy removal.  In the end, this method of thermal protection will be cheaper and easier to maintain.

There's no such thing as reusability after reentry.

Rob,

Forget about using STS thermal protection.  It's old, expensive tech.  It's functional, but that's as far as its merit takes it.  Amazing performance for 1970's technology, but we can do it better / faster / cheaper with fabrics.  Control surfaces can use RCC.  I don't see any reason to go back to using tiles, though.

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#13 2016-04-17 11:05:09

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 5,794
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Re: VentureStar is it possible now

kbd512 wrote:

Rob,

Forget about using STS thermal protection.  It's old, expensive tech.  It's functional, but that's as far as its merit takes it.  Amazing performance for 1970's technology, but we can do it better / faster / cheaper with fabrics.  Control surfaces can use RCC.  I don't see any reason to go back to using tiles, though.

Shuttle thermal protection was "just good enough". Each part of the orbiter was covered by thermal protection that was just barely enough to protect against thermal conditions that part would endure. The reason AFRSI was not applied to the belly was because it couldn't handle heat produced on the belly.

RCC is strong, durable, handle highest heat, but heavy 1986 kg/m³ (124 lb/ft³). Rated for maximum 1,510 °C (2,750 °F)
HRSI (black tiles) are fragile, but light. 1,260 °C (2,300 °F)
LRSI (white tiles) 1,200 °F
AFRSI quilts were rated to 1,500 °F

There were actually two types of black tiles: LI-900 at 9 lb/ft³, and LI-2200 at 22 lb/ft³. Much lighter than RCC.

You can see why LRSI was replaced by AFRSI. It can handle more heat, and less expensive, and more durable. LRSI also came in two types: 9 lb/ft³ and 12 lb/ft³.

DurAFRSI can handle more heat than AFRSI, but not nearly as much as HRSI.

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#14 2016-04-17 16:39:31

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 16,173

Re: VentureStar is it possible now

With the ADEPT fabric Surface temperature on the test article reached 3,100 degrees Fahrenheit or 1,704 degrees Celsius I am wondering if we can reduce the thickness of the other tiles and stretch the fabric across the airframe. as this would reduce the mass of the heat shield making it all that easier to make a single stage to orbit plane....

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#15 2016-04-17 22:17:07

kbd512
Moderator
Registered: 2015-01-02
Posts: 2,959

Re: VentureStar is it possible now

Tom Kalbfus wrote:

Well of course we're going beyond LEO, this is the Mars society isn't it? In a 3+ stage vehicle, the bottom stages are the most expensive. It might be possible to use the top stages if they use something like a nuclear thermal drive once they achieve orbit, the 3+ stages are for going elsewhere other than low Earth orbit. Now a nuclear, or plasma drive might be able to take you from low Earth orbit to low Mars orbit and then back again with a low thrust high impulse option, and such stages might even be returned to Earth and refurbished after a number of uses in orbit, and then launched again on top of another 3+ stage rocket back into orbit.

Ok, but now we're no longer talking about a reusable SSTO like VentureStar.

I think SpaceX, Blue Origin, and ULA already have the right idea by reusing the first stage or first stage rocket engines.

The technology required and loss of lift capability associated with reusable upper stages is quite unattractive and there is no government funded program established for affordable reuse of upper stages.  The cost of manufacturing upper stages is marginal, as most have very high propellant mass fractions and single engines.  To capture and refurbish upper stages from affordable rockets like Falcon and Vulcan, there would have to be a feasibility study to determine recovery and refurbishment costs as opposed to manufacturing new upper stages.  Any upper stage that boosts a payload into a higher orbit is probably not recoverable, so the only opportunity to use recoverable upper stages is limited to heavy lift vehicles boosting payloads to LEO.

I'm going to go way out on a limb and say that the infrastructure and manpower costs outweigh the costs of making a new upper stage.  With composite robotically fabricated tanks and 3D printed rocket engine components, the recovery and refurbishment operation will have to be exceptionally simple and low cost.

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#16 2016-04-17 22:39:32

kbd512
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Registered: 2015-01-02
Posts: 2,959

Re: VentureStar is it possible now

SpaceNut wrote:

With the ADEPT fabric Surface temperature on the test article reached 3,100 degrees Fahrenheit or 1,704 degrees Celsius I am wondering if we can reduce the thickness of the other tiles and stretch the fabric across the airframe. as this would reduce the mass of the heat shield making it all that easier to make a single stage to orbit plane....

That's what I was thinking.  We devise a way to securely fasten Nextel fabrics to a composite substructure in the same way that the orbiter had its various TPS components fastened to an aluminum substructure using fabric blankets and adhesives.  The key is to absolutely minimize the requirement for machined fasteners.  The bolts used to fasten the Nextel fabric to the articulating substructure of ADEPT are probably great for the aerospace hardware industry, but nuts and bolts are heavy, expensive, and there's quite a bit of engineering required to determine what loads the fasteners will be subjected to.

My initial thoughts on this matter are to sew / stitch / weave the fabric around the composite substructure.  Additionally, on-orbit repair methods must be developed to sew patches over damaged TPS fabrics.  Any thoughts on this?

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#17 2016-04-17 22:51:58

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 5,794
Website

Re: VentureStar is it possible now

DurAFRSI used Nextel 440 fabric, stuffed with Saffil batting. Wire mesh of Inconel 617 was sewn on top, using Nextel 440 threads. And metal foil of Inconel 617 was brazed to the foil using traditional brazing compound. What you describe sound suspiciously like DurAFRSI. So my argument is that thermal limits of DurAFRSI are already established.

ADEPT used carbon fibre fabric with some sort of coating. I don't know what the coating is. I suspect the carbon fibre fabric loses flexibility once heated. At least at full temperature. So don't try to fold it away. Nextel and Saffil are ceramic, they can't handle as much heat, but should be more reusable. And fastening system for DurAFRSI sounds more like what you're asking for.

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#18 2016-04-18 00:13:10

kbd512
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Registered: 2015-01-02
Posts: 2,959

Re: VentureStar is it possible now

RobertDyck wrote:

DurAFRSI used Nextel 440 fabric, stuffed with Saffil batting. Wire mesh of Inconel 617 was sewn on top, using Nextel 440 threads. And metal foil of Inconel 617 was brazed to the foil using traditional brazing compound. What you describe sound suspiciously like DurAFRSI. So my argument is that thermal limits of DurAFRSI are already established.

Remember my X wing concept for landing payloads on Mars?  Since this vehicle is to be reusable and the atmosphere on Earth is much denser than Mars, we can use RCC for the wings.  The lifting body, the propellant / propulsion / payload storage container for this vehicle, will be wrapped in Nextel fabric that is then sewn to the vehicle.

DurAFRSI can't be used on the underside of the vehicle.  I don't want to reuse insulating fabrics, either.  I want to discard it after every reentry.  I merely want refurbishment to consist of cutting the fabric off the vehicle and re-wrapping it with new fabric.  The composite substructure must not lose structural integrity at the low temperatures that aluminum does and it must be possible to wrap and sew the fabric to the substructure in locations not subject to high dynamic pressure or high peak heating.

RobertDyck wrote:

ADEPT used carbon fibre fabric with some sort of coating. I don't know what the coating is. I suspect the carbon fibre fabric loses flexibility once heated. At least at full temperature. So don't try to fold it away. Nextel and Saffil are ceramic, they can't handle as much heat, but should be more reusable. And fastening system for DurAFRSI sounds more like what you're asking for.

I'm interested in a method for wrapping the vehicle.  How was the DurAFRSI bonded to the aluminum substructure of the orbiter?  That's what I want to know.

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#19 2016-04-18 00:28:59

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 5,794
Website

Re: VentureStar is it possible now

DurAFRSI.png
DurAFRSI_2.gif
DurAFRSI_3.gif

Patent on NASA technical report server. With two more edge close-out methods: Durable Advanced Flexible Reusable Surface Insulation

Last edited by RobertDyck (2016-04-18 01:25:24)

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#20 2016-04-18 05:17:27

Antius
Member
From: Cumbria, UK
Registered: 2007-05-22
Posts: 1,003

Re: VentureStar is it possible now

kbd512 wrote:
Tom Kalbfus wrote:

Well of course we're going beyond LEO, this is the Mars society isn't it? In a 3+ stage vehicle, the bottom stages are the most expensive. It might be possible to use the top stages if they use something like a nuclear thermal drive once they achieve orbit, the 3+ stages are for going elsewhere other than low Earth orbit. Now a nuclear, or plasma drive might be able to take you from low Earth orbit to low Mars orbit and then back again with a low thrust high impulse option, and such stages might even be returned to Earth and refurbished after a number of uses in orbit, and then launched again on top of another 3+ stage rocket back into orbit.

Ok, but now we're no longer talking about a reusable SSTO like VentureStar.

I think SpaceX, Blue Origin, and ULA already have the right idea by reusing the first stage or first stage rocket engines.

The technology required and loss of lift capability associated with reusable upper stages is quite unattractive and there is no government funded program established for affordable reuse of upper stages.  The cost of manufacturing upper stages is marginal, as most have very high propellant mass fractions and single engines.  To capture and refurbish upper stages from affordable rockets like Falcon and Vulcan, there would have to be a feasibility study to determine recovery and refurbishment costs as opposed to manufacturing new upper stages.  Any upper stage that boosts a payload into a higher orbit is probably not recoverable, so the only opportunity to use recoverable upper stages is limited to heavy lift vehicles boosting payloads to LEO.

I'm going to go way out on a limb and say that the infrastructure and manpower costs outweigh the costs of making a new upper stage.  With composite robotically fabricated tanks and 3D printed rocket engine components, the recovery and refurbishment operation will have to be exceptionally simple and low cost.

This sounds quite sensible.  It occurs to me that reusing a component need not neccesitate returning it to Earth.  Having paid to lift it out of the Earth's gravity well, returning it is in effect a waste of energy.  We have paid for all of the material and operational costs of lifting something into space, only to undo that effort with no real return.  There are other options:

1. Refuel the stage in orbit using fuels (ammonia & oxygen?) extracted from Earth's atmosphere and using it as (effectively) a third stage;
2. Reprocess it in orbit into something else - space station components or grind it up and use it as propellant for a mass driver / ion/ metal oxygen rocket engine.

The first requires that the burn duration and fatigue life are sufficient for more than one use.  The second requires that we design the upper stage for easy dismantling on orbit.

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#21 2016-04-18 07:20:19

Tom Kalbfus
Banned
Registered: 2006-08-16
Posts: 4,401

Re: VentureStar is it possible now

kbd512 wrote:
Tom Kalbfus wrote:

Well of course we're going beyond LEO, this is the Mars society isn't it? In a 3+ stage vehicle, the bottom stages are the most expensive. It might be possible to use the top stages if they use something like a nuclear thermal drive once they achieve orbit, the 3+ stages are for going elsewhere other than low Earth orbit. Now a nuclear, or plasma drive might be able to take you from low Earth orbit to low Mars orbit and then back again with a low thrust high impulse option, and such stages might even be returned to Earth and refurbished after a number of uses in orbit, and then launched again on top of another 3+ stage rocket back into orbit.

Ok, but now we're no longer talking about a reusable SSTO like VentureStar.

I think SpaceX, Blue Origin, and ULA already have the right idea by reusing the first stage or first stage rocket engines.

The technology required and loss of lift capability associated with reusable upper stages is quite unattractive and there is no government funded program established for affordable reuse of upper stages.  The cost of manufacturing upper stages is marginal, as most have very high propellant mass fractions and single engines.  To capture and refurbish upper stages from affordable rockets like Falcon and Vulcan, there would have to be a feasibility study to determine recovery and refurbishment costs as opposed to manufacturing new upper stages.  Any upper stage that boosts a payload into a higher orbit is probably not recoverable, so the only opportunity to use recoverable upper stages is limited to heavy lift vehicles boosting payloads to LEO.

I'm going to go way out on a limb and say that the infrastructure and manpower costs outweigh the costs of making a new upper stage.  With composite robotically fabricated tanks and 3D printed rocket engine components, the recovery and refurbishment operation will have to be exceptionally simple and low cost.

space_shuttle_10.jpg
Here is a reusable upper stage.

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#22 2016-04-18 07:28:00

Tom Kalbfus
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Registered: 2006-08-16
Posts: 4,401

Re: VentureStar is it possible now

Antius wrote:
kbd512 wrote:
Tom Kalbfus wrote:

Well of course we're going beyond LEO, this is the Mars society isn't it? In a 3+ stage vehicle, the bottom stages are the most expensive. It might be possible to use the top stages if they use something like a nuclear thermal drive once they achieve orbit, the 3+ stages are for going elsewhere other than low Earth orbit. Now a nuclear, or plasma drive might be able to take you from low Earth orbit to low Mars orbit and then back again with a low thrust high impulse option, and such stages might even be returned to Earth and refurbished after a number of uses in orbit, and then launched again on top of another 3+ stage rocket back into orbit.

Ok, but now we're no longer talking about a reusable SSTO like VentureStar.

I think SpaceX, Blue Origin, and ULA already have the right idea by reusing the first stage or first stage rocket engines.

The technology required and loss of lift capability associated with reusable upper stages is quite unattractive and there is no government funded program established for affordable reuse of upper stages.  The cost of manufacturing upper stages is marginal, as most have very high propellant mass fractions and single engines.  To capture and refurbish upper stages from affordable rockets like Falcon and Vulcan, there would have to be a feasibility study to determine recovery and refurbishment costs as opposed to manufacturing new upper stages.  Any upper stage that boosts a payload into a higher orbit is probably not recoverable, so the only opportunity to use recoverable upper stages is limited to heavy lift vehicles boosting payloads to LEO.

I'm going to go way out on a limb and say that the infrastructure and manpower costs outweigh the costs of making a new upper stage.  With composite robotically fabricated tanks and 3D printed rocket engine components, the recovery and refurbishment operation will have to be exceptionally simple and low cost.

This sounds quite sensible.  It occurs to me that reusing a component need not neccesitate returning it to Earth.  Having paid to lift it out of the Earth's gravity well, returning it is in effect a waste of energy.  We have paid for all of the material and operational costs of lifting something into space, only to undo that effort with no real return.  There are other options:

1. Refuel the stage in orbit using fuels (ammonia & oxygen?) extracted from Earth's atmosphere and using it as (effectively) a third stage;
2. Reprocess it in orbit into something else - space station components or grind it up and use it as propellant for a mass driver / ion/ metal oxygen rocket engine.

The first requires that the burn duration and fatigue life are sufficient for more than one use.  The second requires that we design the upper stage for easy dismantling on orbit.

Problem is, we cannot maintain used stages in orbit, and returning them to Earth is inexpensive, they just need the heat shields in order to survive. Now as for that nuclear upper stage that can go to Mars and back, it will probably need to be brought back to Earth, after chucking its used nuclear fuel, then it can be refuels and the reactor can be maintained so it is in proper working order for the next mission, I think that is cheaper than building a new nuclear reactor and upper stage. The reason why space travel is so expensive is we've gotten into the habit of throwing things away.

It costs just as much to launch a used stage into orbit as it does to launch a brand new stage into orbit, they both weigh the same, but it costs less to reuse an old stage, than to build a new one each and every time. Though the contractors like throwaway rockets, after all, they're not paying for them, the government is, that is the difference between Boeing and SpaceX. SpaceX pays for the rocket and charges for the launch service, Boeing charges for building the rocket, for Boeing, the cost of building a rocket is not an expense, but a source of revenue, so naturally they are not interested in building reusable stages!

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#23 2016-04-18 09:43:06

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 5,794
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Re: VentureStar is it possible now

Hubble Space Telescope was designed to be re-captured by Shuttle and brought down for periodic maintenance. The reason it wasn't was fear the government would never authorize re-launching if it was ever brought down. Same with your reusable nuclear engine.

Nuclear physics requires a certain minimum critical mass to get the reactor to start. That results in more fissionable material than is necessary for one trip to Mars and back. It could easily have enough material for 10 round trips. However, propellant is the issue. You could build a spacecraft with a reusable TMI/TEI engine, and refillable propellant tank. It may be easier to just replace the whole tank. Russia currently transfers propellant to ISS.

But this thread was supposed to be about a reusable SSTO, not interplanetary.

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#24 2016-04-18 17:20:19

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 16,173

Re: VentureStar is it possible now

Yup agreed try to stay on topic but there is always some wiggle room....

I am thinking that the fabric will need protection on the way up to orbit from some sort of composite shell of which we do not care it it burns up on re-entry as thats just and other shell that is low cost to replace much like the fabrics would be. The tiles are less so and requires all the inspection process to make sure that they are adherd correctly (aka shuttle processing)....Sure would be nice to know what the adept coating might be thou I gave a good guess as to what they might be in that topic....

The airframe will take some punishment with each flight so it would need to be repace or recertified in time as the shuttles were.....

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#25 2016-04-18 21:15:41

kbd512
Moderator
Registered: 2015-01-02
Posts: 2,959

Re: VentureStar is it possible now

RobertDyck wrote:

Hubble Space Telescope was designed to be re-captured by Shuttle and brought down for periodic maintenance. The reason it wasn't was fear the government would never authorize re-launching if it was ever brought down. Same with your reusable nuclear engine.

There are two basic problems with recovery of nuclear stages:

1. Development of a method to separate the reactor / rocket from the fuel tank

There's no upper stage that's designed to be disassembled on-orbit to be returned in the cargo bay of a reusable launch vehicle

I proposed returning STS to flight status to capture and return the 4 RS-25's connected to SLS.  If the orbiters had their landing gear upgraded, this would be feasible.  Keep SLS a 100t lift vehicle and recover that $290M worth of flight hardware instead of sending it to Davy Jones' locker after less than 10 minutes of use.  As in DRM 5, the nuclear upper stages would be payloads.

2. Containment of the core assembly

It's true that there's far less radiation emission shortly after fission stops, but to permit normal work to be performed in close proximity to the core after operations, some sort of lightweight cask is required.

RobertDyck wrote:

Nuclear physics requires a certain minimum critical mass to get the reactor to start. That results in more fissionable material than is necessary for one trip to Mars and back. It could easily have enough material for 10 round trips. However, propellant is the issue. You could build a spacecraft with a reusable TMI/TEI engine, and refillable propellant tank. It may be easier to just replace the whole tank. Russia currently transfers propellant to ISS.

But this thread was supposed to be about a reusable SSTO, not interplanetary.

As you stated, there's more than enough fissionable material in the core of a NTR for multiple restarts.  The primary problem has always been the extreme thermal cycling of the fuel rods.  How many cycles can you execute before the fuel rods are damaged beyond the point of usability?

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