Author Topic: Lessons Learned: Rockets in the 1980s and 1990s and now  (Read 65772 times)

Offline matthewkantar

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #40 on: 12/18/2016 01:04 am »
Yes. So it looks like Blue Origin might be the first to go orbital in a truly "privately funded" enterprise that didn't have some kind of Gov't funding source.

Blue Origin has a contract with NASA right now to provide a suborbital research platform. Earlier on Blue Origin received $22 million from NASA for a pusher escape system in CCDev2.

Matthew

Offline HMXHMX

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #41 on: 12/18/2016 01:41 am »


Today, turbopumps are getting ridiculously cheap, so there is little reason to go pressure-fed.  If I was to embark upon another LV project, it'd be pump-fed.

Spacex spent at least $1m - probably significantly more - on their first Barber Nichols turbopump for Falcon 1.

I think that is quite cheap at that scale but what if you wanted to build a real turbopump for a 22kn engine like Rocket Lab but not electrical? What would you consider reasonable for that, and is there really anything off the shelf? It's still an r&d project with the usual fixed costs.

I know of firms doing this scale of development who can't be spending more than a few hundred K$ on their pumps.

Offline Arch Admiral

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #42 on: 12/18/2016 01:44 am »
OTRAG had a fundamentally wrong approach to building an orbital booster - strapping together lots of tiny mass-produced rockets. It's a basic principle of rocket design that one big tank is lighter than many small ones, and one big engine is lighter and more reliable than a battery of small ones. They never could have launched a useful payload with that design.

I read the Soviet disinformation at the time and it was laughable. The basic claim was that OTRAG was a cover for a secret CRUISE MISSILE development program run by the the West German Luftwaffe, to give the "fascist revanchists" an independent nuclear strike capability. They never explained how West Germany would get the warheads or the fissionables to make them.

I don't know if this propaganda campaign really had any role in the collapse of OTRAG but it is certainly possible. NATO was so sensitive to Soviet paranoia about West Germany at that time that a special single-stage version of Pershing II was developed to replace the 72 Pershing IB missiles in Luftwaffe service. It only had the range to reach the middle of Poland.

Offline Robotbeat

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #43 on: 12/18/2016 02:48 am »
Yes. So it looks like Blue Origin might be the first to go orbital in a truly "privately funded" enterprise that didn't have some kind of Gov't funding source.

Blue Origin has a contract with NASA right now to provide a suborbital research platform. Earlier on Blue Origin received $22 million from NASA for a pusher escape system in CCDev2.

Matthew
Not just that, but they actually got paid for BE-3 milestones from NASA as well.

I don't get this obsession with avoiding any government help whatsoever. Did you avoid highways as well? It's a dumb contest when taken to extremes.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline Katana

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #44 on: 12/18/2016 03:09 am »
Yes. So it looks like Blue Origin might be the first to go orbital in a truly "privately funded" enterprise that didn't have some kind of Gov't funding source.

Blue Origin has a contract with NASA right now to provide a suborbital research platform. Earlier on Blue Origin received $22 million from NASA for a pusher escape system in CCDev2.

Matthew
Not just that, but they actually got paid for BE-3 milestones from NASA as well.

I don't get this obsession with avoiding any government help whatsoever. Did you avoid highways as well? It's a dumb contest when taken to extremes.

Other failed projects in 80~90s (Kistler, etc) also have some goverment funding .

There is little meaning arguing on the purity of word "commercial".

Offline Katana

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #45 on: 12/18/2016 03:35 am »
And yet the "Sea Dragon" concepts were all (AFAIK) pressure fed.

OTRAG was a victim of Russian disinformation.

I'm guessing Von Braun went with turbo pumps to side step issues with triggering combustion instability caused by (potential) pressure fluctuations of positive displacement pumps. Which John Whiteheads groups reckon are the best option up to about 5 Klbs. Today a turbine can be CNC machined in 19 hours, as is done for the turbochargers on Mack trucks.

AMROC died on the death of it's CEO basically. His advice on buying parts IE buy what's on the spec, don't insist on mods when buying from aerospace parts houses, is part of what drove SX into mfg in house.

Ablative cooling sounds like a good idea for a single use engine but IRL only solids are really fired once. All others are fired at least twice for testing and that makes ensuring the state of the ablative char inside the rocket after that firing critical. That is there's still enough left for the launch and that it does not go on cooking after the test fire.  I think this was the single worst idea Boeing had for the engine on the Delta IV.

For anyone worried about coking they should consider that LO2 cooling of a 40 000lb combustion chamber was done 25 years ago by NASA, including deliberate holes in the wall to make the LO2 leak into the chamber during firing. It did not sustain any further damage. It's time the fear of LO2 cooling was put to bed. Both HTP and NTO have been used as coolants on other rockets (IIRC because amines have a tendency to explode in cooling channels).

Why Von Braun invent turbopump so early and did Not choose pressure fed for V2? Early version of scud short range missiles are pressure fed , later extended range popular version have pumps. Is V2 designed for potential launcher instead of only for short range missile?

Coking is Not a problem , modern hydrogenated refined kerosene for insectcide solvents are even better than RP-1, purified to <1ppm sulfur. Actually JP-7 for SR71 is made of it , and have caused shortening of insectcide Flit for one year.
https://en.m.wikipedia.org/wiki/JP-7

But small engines below certain scale are impossible to regenertive cooling , since the ratio of surface area / volume rise too high at small scale.

Offline Lars-J

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #46 on: 12/18/2016 04:12 am »
And yet the "Sea Dragon" concepts were all (AFAIK) pressure fed.

"Pressure fed" appears to be one of the concepts of rocketry that sounds oh so much simpler in theory than it is in practice. (like hybrid rockets) And none of the Sea Dragon concepts got anywhere close to reality.

It may also be one of the technologies that just doesn't scale well.
« Last Edit: 12/18/2016 04:13 am by Lars-J »

Offline Robotbeat

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #47 on: 12/18/2016 04:32 am »
Hey, I don't think pressure fed is as bad of an idea as hybrids.
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Offline Steven Pietrobon

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #48 on: 12/18/2016 06:23 am »
But small engines below certain scale are impossible to regenertive cooling , since the ratio of surface area / volume rise too high at small scale.

The 10 kN Ausroc I kerolox engine used regenerative cooling, so that places an upper limit. That engine was pretty small.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline john smith 19

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #49 on: 12/18/2016 01:13 pm »
"Pressure fed" appears to be one of the concepts of rocketry that sounds oh so much simpler in theory than it is in practice. (like hybrid rockets) And none of the Sea Dragon concepts got anywhere close to reality.

It may also be one of the technologies that just doesn't scale well.
A number of upper stages are pressure fed, typically with hypergols. It eliminates the turbopump and ignition system.

The issues with pressure fed is the tank weight and perceived loss of performance. It's real benefit (cheapness) has not, in reality, been a key design driver for any government space programme. Project cost was what drove Sea Dragon. it's strategy was cut the $/lb by making a huge lump of payload available in one go.

Which is the SLS and ITS strategy as well.

Solids OTOH are very deceptive. They truly look simple (who can't set off a firewwork?) but have as much trouble as liquids with combustion stability, plus the large quantity of explosive you have packed in one place. They also can be prone to deflagration-to-detonation transition, when the whole lump goes up in one go.

Military systems prize absolute performance and storability. Solids and toxic hypergols  are the best in these areas. For civilian (and especially human rated) systems they should not be used. There benefits simply don't outweigh their downsides, which are substantial. those benefits are simply not relevant to the priority of a civilian and / or commercial programme.

MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline Kabloona

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #50 on: 12/18/2016 03:19 pm »

Solids OTOH are very deceptive. They truly look simple (who can't set off a firewwork?) but have as much trouble as liquids with combustion stability, plus the large quantity of explosive you have packed in one place. They also can be prone to deflagration-to-detonation transition, when the whole lump goes up in one go.

If this discussion is about lessons on how to develop a small or medium expendable rocket, solids are still a viable option, because there are plenty of tested, "off the shelf" propellant formulations, grain designs, composite case designs, nozzle designs, TVC systems, tooling, etc, already in place. No one is starting with "clean sheet" solids designs unless (a) they have a lot of money and development time, or (b) are designing a very small vehicle.

Pegasus and Taurus adapted existing motor designs from Small ICBM and Peacekeeper quite successfully. And Class 1.3 HTPB propellants are quite difficult to detonate. In fact, a "zero card gap" Class 1.3 HTPB propellant won't detonate even when placed in direct contact with a high explosive booster.

Going the solid motor route served Pegasus and Taurus well in terms of short development schedules and relatively low development cost. And although Orbital opted to go liquid on Antares, they still chose a solid third stage for "Block 1" because it was a shorter development cycle and lower schedule risk.

And if you want to talk about "large quantities of explosives," the most recent "large explosions" I can remember have involved by SpaceX helium bottles, an Antares liquid engine failure, and a fatal nitrous oxide tank explosion. None of which involved composite solid propellants, whose safety record in recent years has been quite good.

But please let's not rehash the eternal "which is better/safer" argument. I merely observe that solids "can" be a safe, short-development cycle, and cost-effective option for small and medium LV's, as demonstrated by Pegasus and Taurus.
« Last Edit: 12/18/2016 04:15 pm by Kabloona »

Offline Gliderflyer

But small engines below certain scale are impossible to regenertive cooling , since the ratio of surface area / volume rise too high at small scale.

The 10 kN Ausroc I kerolox engine used regenerative cooling, so that places an upper limit. That engine was pretty small.

You can use regenerative cooling on engines even smaller than that. The 40 lb (~175 N) RCS thrusters on the Lynx use regenerative cooling.
I tried it at home

Offline Jim

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #52 on: 12/18/2016 05:59 pm »

Ablative cooling sounds like a good idea for a single use engine but IRL only solids are really fired once. All others are fired at least twice for testing and that makes ensuring the state of the ablative char inside the rocket after that firing critical. That is there's still enough left for the launch and that it does not go on cooking after the test fire.  I think this was the single worst idea Boeing had for the engine on the Delta IV.


wrong.  engines with ablative nozzles can be test fired without the nozzle for acceptance

Offline Jim

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #53 on: 12/18/2016 06:08 pm »

1.  The issues with pressure fed is the tank weight and perceived loss of performance. It's real benefit (cheapness) has not, in reality, been a key design driver for any government space programme.


2.  Military systems prize absolute performance and storability. Solids and toxic hypergols  are the best in these areas. For civilian (and especially human rated) systems they should not be used. There benefits simply don't outweigh their downsides, which are substantial. those benefits are simply not relevant to the priority of a civilian and / or commercial programme.


Wrong takeaways again

1.  Yes, it has.  See the original Delta.  And also see the EELV-S.

2.  Wrong again.  You are overstating the issues with hypergols.  And the fact that every GSO comsat, along with many others, uses them proves that the benefits outweigh downsides.  Not to mention that most are commercial and Dragon, CST-100, Cygnus, etc are civilian

Offline edkyle99

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #54 on: 12/18/2016 07:39 pm »
1.  Yes, it has.  See the original Delta.  And also see the EELV-S.

2.  Wrong again.  You are overstating the issues with hypergols.  And the fact that every GSO comsat, along with many others, uses them proves that the benefits outweigh downsides.  Not to mention that most are commercial and Dragon, CST-100, Cygnus, etc are civilian
And ISS, which is even routinely refueled with the stuff!

 - Ed Kyle

Offline Katana

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #55 on: 12/19/2016 12:00 am »
"Pressure fed" appears to be one of the concepts of rocketry that sounds oh so much simpler in theory than it is in practice. (like hybrid rockets) And none of the Sea Dragon concepts got anywhere close to reality.

It may also be one of the technologies that just doesn't scale well.
A number of upper stages are pressure fed, typically with hypergols. It eliminates the turbopump and ignition system.

The issues with pressure fed is the tank weight and perceived loss of performance. It's real benefit (cheapness) has not, in reality, been a key design driver for any government space programme. Project cost was what drove Sea Dragon. it's strategy was cut the $/lb by making a huge lump of payload available in one go.

Which is the SLS and ITS strategy as well.

Solids OTOH are very deceptive. They truly look simple (who can't set off a firewwork?) but have as much trouble as liquids with combustion stability, plus the large quantity of explosive you have packed in one place. They also can be prone to deflagration-to-detonation transition, when the whole lump goes up in one go.

Military systems prize absolute performance and storability. Solids and toxic hypergols  are the best in these areas. For civilian (and especially human rated) systems they should not be used. There benefits simply don't outweigh their downsides, which are substantial. those benefits are simply not relevant to the priority of a civilian and / or commercial programme.
Pressure feds use insane amount of helium or require complicated pressurization when pressure goes beyond upperstage level  0.8--1MPa.

Solids are really easier with modern polymer binders.
« Last Edit: 12/19/2016 12:04 am by Katana »

Offline Robotbeat

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #56 on: 12/19/2016 12:04 am »
Easier if you have an ICBM industrial base (which we do have in the US).
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Offline john smith 19

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #57 on: 12/19/2016 07:34 am »
Pressure feds use insane amount of helium or require complicated pressurization when pressure goes beyond upperstage level  0.8--1MPa.
The simplest pressure fed is regrettably the autogenous system of Titan II, unless both propellants are cryogens and you tap some of them through heat exchange piping, which AFAIK has never been flown.  Note that COPV's for LOX have been available since the mid 90's, according to HMX
Quote
Solids are really easier with modern polymer binders.
If you buy them in from another company that already makes them.

And ISS, which is even routinely refueled with the stuff!

 - Ed Kyle
I'd love to know how NASA would have handled that task if the Russians weren't doing it.

To return to the OP and the thread topic can we agree that using hypergols for a new main stage for a new company is a bad idea?

Wrong takeaways again

1.  Yes, it has.  See the original Delta.  And also see the EELV-S.
I stand corrected. That should be most government programmes. So pressure fed systems should be considered an option for startup companies.
Quote
2.  Wrong again.  You are overstating the issues with hypergols.  And the fact that every GSO comsat, along with many others, uses them proves that the benefits outweigh downsides.  Not to mention that most are commercial and Dragon, CST-100, Cygnus, etc are civilian
I'd stand a foot away from an open container of Kerosene or HTP. I'd never dream of doing that with NTO or UDMH.

The fact that NTO/amines do give better Isp than the only current major alternative oxidizer (HTP) means people put up with their handling problems and cost (last time I checked UMDH was $60/lb but that was a while back. Since those companies have already sunk the cost of infrastructure necessary to handle them it's a null problem.

Since this is in the context of a startup company  you have the choice of buying in expertise, avoiding the need for it or using other propellants.

Taking the path of least resistance and least necessity to acquire rocket engine knowledge gets you the Pegasus design.

Which AFAIK has the highest $/lb to orbit price of any launcher.  :(

While that strategy could be repeated today I cannot see why anyone but a national government desperate to have an all solid LV would fund it, since other architectures give better performance
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline john smith 19

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #58 on: 12/19/2016 07:44 am »
Going the solid motor route served Pegasus and Taurus well in terms of short development schedules and relatively low development cost. And although Orbital opted to go liquid on Antares, they still chose a solid third stage for "Block 1" because it was a shorter development cycle and lower schedule risk.
It's a very pragmatic approach if you a)Have the cash for it b)Have a relationship with a solids supplier (as Orbital had IIRC).
Quote
And if you want to talk about "large quantities of explosives," the most recent "large explosions" I can remember have involved by SpaceX helium bottles, an Antares liquid engine failure, and a fatal nitrous oxide tank explosion. None of which involved composite solid propellants, whose safety record in recent years has been quite good.
All of those were events and only the last one was down to the inherent nature of the material (there's a reason liquids and gases have a "critical temperature"   :( )

A big lump of explosive remains a big lump of explosive. As for the card test that only proves you need a lump bigger than 6" in dia to propagate an explosion. The Pegaus is 50" in dia.
Quote
But please let's not rehash the eternal "which is better/safer" argument. I merely observe that solids "can" be a safe, short-development cycle, and cost-effective option for small and medium LV's, as demonstrated by Pegasus and Taurus.
Agreed.

Can we also agree it produces the highest $/lb to orbit prices as well?
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline Nomic

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Re: Lessons Learned: Rockets in the 1980s and 1990s and now
« Reply #59 on: 12/19/2016 09:10 am »
The Beal pressurization system was meant to be cold helium IIRC, all ablative engine so no source of heat to warm the helium, and with no cryogens helium stored at ambient so an even larger volume of helium required. Heavy and expensive on helium.

The system proposed for the Loral/Microcossom Aquarius LV sounded interesting, GH2 to pressurize LOX. They did some tests as well.

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