Lessons Learned: Rockets in the 1980s and 1990s and now

[Katana]

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.

Pressure fed hydrolox SSTO?

[Robotbeat]

Never been flown??? Shuttle flew over 100 times!

[Katana]

Solids are easier than pressure feds even when built in house. No commercial pressure fed vehicles cross the Von Karman line with customer payloads regularly as solid sounding rockets of UP Aerospace (amateur CSXT derivative).

Though these small liquid vehicle projects are claiming "orbital launch" or "manned tourism". What a shame.

[Robotbeat]

Hybrids also were the only commercial spacecraft to send people above the Karman Line so far. Doesn't make it superior to other options.

Pressure fed beats solids if you're attempting reuse. See Masten.

[Jim]

The simplest pressure fed is regrettably the autogenous system of Titan II,

Titan II wasn't pressure fed.  the autogenous system on the Titan II was just used to provide ullage pressure for the turbo pumps.  The N2O4 was taken from the turbo pump output and heated. The A-50 was pressurized by cooled generator output.

 unless both propellants are cryogens and you tap some of them through heat exchange piping, which AFAIK has never been flown. 

LOX on the shuttle was heated through an heat exchanger

[Jim]

A big lump of explosive remains a big lump of explosive.

Solid propellant is not an explosive

[Jim]

1.  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.

2.  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. 

1.  It is not a big deal, you just have to be up wind.  Actually, HTP is more dangerous

2. UDMH is not used much any more.  Either hydrazine or MMH.

[Katana]

Hybrids also were the only commercial spacecraft to send people above the Karman Line so far. Doesn't make it superior to other options.

Pressure fed beats solids if you're attempting reuse. See Masten.

SS2 is also the only commercial spacecraft to kill people, including N2O explosion of hybrids. SS2 is still delaying service today.

[Katana]

1.  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.

2.  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. 

1.  It is not a big deal, you just have to be up wind.  Actually, HTP is more dangerous

2. UDMH is not used much any more.  Either hydrazine or MMH.

NTO is horribly toxic , RFNA is acceptable, WFNA(common industrial fuming nitric acid) is fairly safe and "green".

[Jim]

NTO is horribly toxic , RFNA is acceptable, WFNA(common industrial fuming nitric acid) is fairly safe and "green".

NTO is acceptable

[notsorandom]

Hybrids also were the only commercial spacecraft to send people above the Karman Line so far. Doesn't make it superior to other options.

Pressure fed beats solids if you're attempting reuse. See Masten.

SS2 is also the only commercial spacecraft to kill people, including N2O explosion of hybrids. SS2 is still delaying service today.

He was referring to Space Ship One. Which had a safe if not short career. SS2 is a whole other beast.

[john smith 19]

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.

And yet that's basically the Microcosm plan in a nutshell as well.

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.

In this case storing at ambient is better as the GHe would have been more energetic. If those tanks were in the propellant tanks they would have absorbed heat from the main tank contents. The joker is wheather they'd absorb so much heat they'd freeze a layer of propellant on the tanks. 

Titan II wasn't pressure fed.  the autogenous system on the Titan II was just used to provide ullage pressure for the turbo pumps.  The N2O4 was taken from the turbo pump output and heated. The A-50 was pressurized by cooled generator output.

True. I was also thinking about it for it's use in Sea Dragon.

LOX on the shuttle was heated through an heat exchanger

I did include the word both in the relevant sentence but in fact you'd be right as Shuttle did use GH2 for ET pressurization as well. Oddly Ariane 5 does not.

I can only presume I forgot Shuttle as it couldn't make orbit on its own without the SRB's.

[john smith 19]

1.  It is not a big deal, you just have to be up wind.  Actually, HTP is more dangerous

2. UDMH is not used much any more.  Either hydrazine or MMH.

NTO is horribly toxic , RFNA is acceptable, WFNA(common industrial fuming nitric acid) is fairly safe and "green".

But both committed the cardinal sin of delivering inferior Isp and storability (which needs to be in decades) for the military systems the were originally developed for.  Once the investment had been made any government funded system would have to demonstrate it's fuel could at least match NTO/Amine for Isp and density impulse.

John Clarke's "Ignition" is very good on the development history.

From this 
https://sites.wff.nasa.gov/code803/docs/sac/SAC%20Presentations HYPERGOL%20HAZARDS%20PRESENTATION.pdf

ACGIH lists Amine exposure limits about  the 3ppm level for MMH

Now compare this with HTP limits

https://www.cdc.gov/niosh/docs/81-123/pdfs/0335.pdf

But note the consequences of exposure.

HTP. Irritation of lungs and eyes. So goggles a good idea and maybe a mask.
NTO/ Amines. Death.

It seems the human body reacts to HTP at a lower concentration in air (bad) but the effects are quite mild (good). In contrast the effects of NTO and amine fuels need a higher concentration but are much more severe. This is relevant because start ups are likely to be less process driven and more schedule driven. HTP is relatively forgiving (as John Carnack at Armadillo Aerospace noted) in a way NTO/Amines simply are not. HTP left alone will decay to water and O2. NTO or Amine fuels will evaporate into a toxic cloud.  Anyone not wearing breathing apparatus and probably a full body suit will have a very bad day.

I think the general lesson learned is that avoiding highly toxic propellants that remain highly toxic for long periods of time is a good idea for a new company.

I know which I'd rather handle.   

[Jim]

for the military systems the were originally developed for. 

Wasn't just military

[mmeijeri]

NTO is acceptable

Just out of curiosity, are there any low-performance storable oxidisers that are a lot easier to handle than nitric acid?

[john smith 19]

Now that we have a bunch of new companies planning to fly new rockets, I thought it would be useful to examine the efforts in the past that mostly failed, and why they failed. Sometimes it was just a question of an early failure that killed the company, and knowing failure modes of the past could be useful.

Kistler had a nastier problem, a design that didn't close under a billion dollars. They spend hundreds of millions of dollars and got 75 percent done. The last 25 percent apparently was going to cost a billion dollars. They should have hired Elon.

Kistler had a design done by a group of ex-NASA engineers. This was very attractive to VC types who made them the best funded startup in this area.

So they ran it like a cost-plus Big Aerospace prime contractor would until they ran out of money, not realizing that this not being a Government project there would not be any more money. 

It did however offer full reusability.

But I'd ask a more critical question.

Why?

The world does not need yet another liquid fueled TSTO ELV (and the artillery range to launch it over), which is the lowest risk high(ish) performance architecture that currently exists.

We know that can be done for about $300m if you start with a small single engine LV, bring most of your major mfg in house, size your major mfg tools for the biggest size you expect to make and don't use a 1000 page govt purchasing contract. That's basically what SX did.

So how many launches would it have to make at what price to recover that money? That's the question any non-angel investor will ask.

But you can scale down the problem. Then you're in cubesat launching territory.

Again how many launches to break even?

When it matures (if it has a chance to establish a track record) you'll have a system with a 3-5% failure rate, like every other ELV.  Today you might consider recovering the first stage, wheather that will lower prices is another matter, as is wheather it will improve the reliability time will also tell (I don't see why it shouldn't, but with the first launch of a new design still having a 50/50 risk of failure after 70 years I'd say things are not cut and dried. Who thought pressurizing GHe tanks in a sub cooled LO2 bath would trigger an explosion before it did?) 

The problem is control.  All of these systems put the customers schedule on the mfg/operators. In the US only Pegasus seems to be slightly more responsive to the customer, at a price of > $30000 per lb IIRC. ULA are claiming better. We'll have to see what they deliver.

And as long as each system is unique, and the operator is basically a division of the same company that makes it, they always will be. 

What will your system offer that breaks this cycle? If you offer nothing to address this there is very little point in pursuing a design in the first place.

I will note that the principles of design-to-minimum-cost suggest you go for the best simple system as the first stage, with progressively more expensive structures and mfg techniques as you approach orbit.  But that's for a full ELV.

That said the economics of mfg have changed over the decades, sometimes with critical knock on effects on mass. What has not are the Isp ranges of conventional propellants. Only air breathing systems can deliver Isps radically above LO2/LH2, permitting (potentially) the use of heavier, more robust structures.

[Jim]

and the artillery range to launch it over)

They are not going away even for RLV's.  Current space launch ops are to be around for quite some time.  It isn't going to be like aircraft

[Katana]

Hybrids also were the only commercial spacecraft to send people above the Karman Line so far. Doesn't make it superior to other options.

Pressure fed beats solids if you're attempting reuse. See Masten.

SS2 is also the only commercial spacecraft to kill people, including N2O explosion of hybrids. SS2 is still delaying service today.

He was referring to Space Ship One. Which had a safe if not short career. SS2 is a whole other beast.

VG didn't enter space tourism service with SS1, but paid 10 years and multiple lives on SS2.
And all N2O hybrids have the basic problem of bubble compression detonation, even in tiny engines.
http://www.spl.ch/publication/SPL_Papers/N2O_safety_e.pdf

[Katana]

1.  It is not a big deal, you just have to be up wind.  Actually, HTP is more dangerous

2. UDMH is not used much any more.  Either hydrazine or MMH.

NTO is horribly toxic , RFNA is acceptable, WFNA(common industrial fuming nitric acid) is fairly safe and "green".

But both committed the cardinal sin of delivering inferior Isp and storability (which needs to be in decades) for the military systems the were originally developed for.  Once the investment had been made any government funded system would have to demonstrate it's fuel could at least match NTO/Amine for Isp and density impulse.

John Clarke's "Ignition" is very good on the development history.

From this 
https://sites.wff.nasa.gov/code803/docs/sac/SAC%20Presentations HYPERGOL%20HAZARDS%20PRESENTATION.pdf

ACGIH lists Amine exposure limits about  the 3ppm level for MMH

Now compare this with HTP limits

https://www.cdc.gov/niosh/docs/81-123/pdfs/0335.pdf

But note the consequences of exposure.

HTP. Irritation of lungs and eyes. So goggles a good idea and maybe a mask.
NTO/ Amines. Death.

It seems the human body reacts to HTP at a lower concentration in air (bad) but the effects are quite mild (good). In contrast the effects of NTO and amine fuels need a higher concentration but are much more severe. This is relevant because start ups are likely to be less process driven and more schedule driven. HTP is relatively forgiving (as John Carnack at Armadillo Aerospace noted) in a way NTO/Amines simply are not. HTP left alone will decay to water and O2. NTO or Amine fuels will evaporate into a toxic cloud.  Anyone not wearing breathing apparatus and probably a full body suit will have a very bad day.

I think the general lesson learned is that avoiding highly toxic propellants that remain highly toxic for long periods of time is a good idea for a new company.

I know which I'd rather handle.   

Nitric Acid is much less volatile than NTO.
Amines (R-NH2) have toxicity and volatility much less than Hydrazines (R-NH2-NH2-R).
Though they have relatively low energy, poorer long term storable behavior, high freezing point.

Nitric Acid / Amine or Nitric Acid / Turpinetine combination have been successfully used (before NTO and Hydrazine) in French "Diamond" launcher to orbit.

Interorbital Systems (remains of OTRAG) is still using Nitric Acid / Turpinetine today, though with a very small rocket.

[Katana]

NTO is acceptable

Just out of curiosity, are there any low-performance storable oxidisers that are a lot easier to handle than nitric acid?

No oxidizer easier to handle than white nitric acid (without NTO added), except solids (AP) and Air.

Airbreathing propulsion up to Mach 4 with conventional turbo/ramjet (NOT SCRAMJET) is feasible for suborbitals with apogee (coasting) up to the Karman line.