• Quick note - the problem with Youtube videos not embedding on the forum appears to have been fixed, thanks to ZiprHead. If you do still see problems let me know.

Ares vs. Jupiter Rocket Designs

DrRocket said:
You are utterly wrong. Class 1.1 solid rocket propellants do detonate and are actually high explosives. Such propellants are in use as we speak. In large rocket motors. Burn rates on such propellants are in the range of ).5 inches per second. Detonation velocities of the same propellants are thousands of meters per second. Burn rate has nothing to do with detonation rates or detonability.

Class 1.3 propellants generally are not considered to detonate -- which means that detonation waves tend to damp out, the propellants have a large critical diameter, or even that the hole in the witness plate was ragged rather than clean. They are explosives. APCP propellants quite obviously contain AP (ammonium perchlorate) AP is detonable.

People who think that APCP propellants are safe are themselves dangerous.

Accidents involving either the manufacture of APCP propellant or rocket case ruptures are quite impressive. And dangerous.
Click to expand...

From our friend Wikipedia.org (note the last sentence)...
In ballistics and pyrotechnics, a propellant is a generic name for chemicals used for propelling projectiles from guns and other firearms.
Propellants are nearly always chemically different from high explosives as used in shells and mines to produce a blasting effect. However, some explosive substances can be used both as propellants and as bursters, as for example gunpowder, and some of the ingredients of a propellant may be similar, though differently proportioned and combined, to those of an explosive.
A very typical propellant burns rapidly but controllably and non explosively, to produce thrust by gas pressure and thus accelerates a projectile or rocket. In this sense, common or well known propellants include, for firearms, artillery and solid propellant rockets:

Propellants that explode in operation are of little practical use currently, although there have been experiments with Pulse Detonation Engines.
 
Last edited:
mhaze said:
...
Propellants that explode in operation are of little practical use currently, although there have been experiments with Pulse Detonation Engines.
Click to expand...

In current applications propellants are not intended to explode. That does in no way change the fact that the propellants are explosives, and in the case of class 1.1 solid propellants in fact high explosives. Explosives are capable of undergoing combustion in more than one mode. The explosives used in solid rockets undergo relatively slow combustion when used as designed. However, they are capable of much more rapid combustion. In some cases the can exhibit true detonation. Been there, done that, it isn't pretty.

Even the class 1.3 propellants, ones such as you mentioned that use HTPB or PBAN as the binder are explosive. They do not detonate under normal circumstances, basically meaning that they have a large critical diameter. But if one breaks up, and a lot of surfeace area is exposed the rapid deflagration will seem like an explosion to anyone in the vicinity.

Pulse detonation engines are basically advanced replacements for jet engines and use liquid fuel and with a detonation pulse in a gaseous mixture of fuel and oxidizer. The objective is to produce a particularly efficient thermodynamic cycle. That cycle does seem to be applicable to rockets.


This is a case burst, propellant fracture and rapid deflagration of many of the fragments. The test stand was destroyed.http://www.capcomespace.net/dossiers/espace_US/lanceurs_US/titan/titan 4 explosion aout 1998.jpg
 
DrRocket said:
Pulse detonation engines are basically advanced replacements for jet engines and use liquid fuel and with a detonation pulse in a gaseous mixture of fuel and oxidizer. The objective is to produce a particularly efficient thermodynamic cycle. That cycle does seem to be applicable to rockets.
http://www.capcomespace.net/dossiers/espace_US/lanceurs_US/titan/titan 4 explosion aout 1998.jpg
Click to expand...

Do rocket bipropellants just mix efficiently enough that there's no need to screw with the current power cycle? Why don't turbines work that well? Just the vagaries and complexities of mixing air and aerosolized fuel, and harvesting power from it at the same time?

And just for point of comparison, what are the chances that the ignition goes wonky and the fuel/oxidizer mixture and a liquid fuel rocket explodes? Or the fuel containment gets a leak? Or the o-rings in the lines get screwed up?

Is there actually any sort of rocket that can't explode?
 
Okay ... let's try common sense examples ....

If you insist that a solid rocket propellant like APCP is an explosive, please describe how you could make it explode. I don't think there is any way to that.

If you take a chunk of APCP and ignite it in the open on the ground, it'll smoulder, make a lot of smoke, and glow brightly. But, it won't explode. (This is how we dispose of unused propellant grains.)

If you encase APCP in a sealed container and ignite it, the container may burst due to the pressure, but as soon as that happens, the APCP will stop burning. It won't explode. (This scenario happens when a nozzle of a rocket motor gets clogged.)

You could attach a real explosive to the APCP and detonate the explosive. All that would happen is that the APCP will break up. It won't explode. (NASA tested this for the Shuttle's SRBs and, unfortunately, demonstrated it for real after the Challenger accident.)

Possibly, you could grind it up, but it wouldn't be rocket propellant any more. That would be like saying aluminum is an explosive because aluminum powder is.

-- Roger
 
Last edited:
jadebox said:
Okay ... let's try common sense examples ....

If you insist that a solid rocket propellant like APCP is an explosive, please describe how you could make it explode. I don't think there is any way to that.

If you take a chunk of APCP and ignite it in the open on the ground, it'll smoulder, make a lot of smoke, and glow brightly. But, it won't explode. (This is how we dispose of unused propellant grains.)

If you encase APCP in a sealed container and ignite it, the container may burst due to the pressure, but as soon as that happens, the APCP will stop burning. It won't explode. (This scenario happens when a nozzle of a rocket motor gets clogged.)

You could attach a real explosive to the APCP and detonate the explosive. All that would happen is that the APCP will break up. It won't explode. (NASA tested this for the Shuttle's SRBs and, unfortunately, demonstrated it for real after the Challenger accident.)

Possibly, you could grind it up, but it wouldn't be rocket propellant any more. That would be like saying aluminum is an explosive because aluminum powder is.

-- Roger
Click to expand...

Yes, I'll add to your list gasoline and or kerosene. RP1 is rocket fuel, so we are dealing with a rocket fuel.

By Dr. Rocket's criteria, these are explosive (keep in mind we all know that the vapor is explosive) but we are all well aware of gasoline, what it is and is not, and it is not "an explosive" by any contemporary use of the word.

Aluminum powder? Again by Dr. Rocket's criteria, it would be an explosive. Yet anybody with a slight familiarity with the subject knows that it is the particle size which is critical in this issue - in fact aluminum powders are so graded.

APCP can like anything cause an overpressurization of a container and that container can structurally fail, in which case parts of metal go flying off, and people can and have gotten hurt. That does not make it an explosive material.

RE detonation engines, a 10 pound thrust motor will cause people 10-30 miles away to be calling the sheriff about the racket. So they are not likely to be used for thrust purposes....

I understand from Jadebox that the classification of the APCP chemical as "explosive" has been challenged in court formally. Dr. Rocket should have no need to repeat himself regarding the 1.1 and 1.3 clasifications (which I presume are the challenge) because it is obvious that we are aware of those and do not dispute that those clasifications, which are/have been formally challenged, exist as this time.
 
mhaze said:
... the 1.1 and 1.3 clasifications...
Click to expand...

Those were DOT classifications. I believe the DOT has switched to using similar UN classifications now. APCP was classified as 1.3 because, during transport, it should be handled in the same manner as the explosives which were included in the 1.3 class.

The National Association of Rocketry and the Tripoli Rocketry Association are not challenging the DOT's classification of APCP. They are challenging the inclusion of APCP in the Bureau of Alcohol, Tobacco and Firearms's list of explosives. The challenge is being made on several grounds, but the main one is that APCP is simply not an explosive in its intended use as a rocket propellant.

Back on topic ....

As I said earlier, there are many problems with using solid rocket boosters on manned rockets. Although, they've proven very reliable for the Shuttle, there are challenges that NASA will have to overcome to use them for Ares. The "pogo" problem is especially serious.

I would guess that the SRBs on the Shuttle exhibit the same "problem," but that the configuration of the rocket dampens the effect so it isn't really a problem. If this is true, the Jupiter proposal would seem to have already licked that problem. So, that would be a point in Jupiter's favor - at least until NASA's engineers figure out how to fix the problem.

-- Roger
 
Last edited:
jadebox said:
Those were DOT classifications. I believe the DOT has switched to using similar UN classifications now. APCP was classified as 1.3 because, during transport, it should be handled in the same manner as the explosives which were included in the 1.3 class.

-- Roger
Click to expand...
I stand corrected. It is a frikking alphabet soup of classifications, overlaid with multiple contradictory government agency regulations and vagueness. Again, however, we cannot consider a regulatory classification as a scientific definition.
 
jadebox said:
...

Back on topic ....

As I said earlier, there are many problems with using solid rocket boosters on manned rockets. Although, they've proven very reliable for the Shuttle, there are challenges that NASA will have to overcome to use them for Ares. The "pogo" problem is especially serious.

...
-- Roger
Click to expand...

Pogo is a problem that is unique to liquid rockets. There is no such problem with solids. The closest solid rocket phenomena is something called acoustic burning instability, but that has not been much of an issue since the early Minuteman days with propellant based on casting powder.

There is currently a minor issue being discussed for Ares 1 with involving what is being called thrust oscillation. But in this case the issue has arisen largely from analytical studies that indicate a large structural response on the core vehicle to a very small hypothetical pressure oscillation in the the solids. It is based on pressure oscillations seen in the 4-segment SRBs with an amplitiude on the order of 1 psi. Acoustic and dynamics analyses of rockets at this early stage in a program are notoriously inaccurate and this issue will probably not be resolved until some real test data is available.
 
jadebox said:
Okay ... let's try common sense examples ....

If you insist that a solid rocket propellant like APCP is an explosive, please describe how you could make it explode. I don't think there is any way to that.

If you take a chunk of APCP and ignite it in the open on the ground, it'll smoulder, make a lot of smoke, and glow brightly. But, it won't explode. (This is how we dispose of unused propellant grains.)

If you encase APCP in a sealed container and ignite it, the container may burst due to the pressure, but as soon as that happens, the APCP will stop burning. It won't explode. (This scenario happens when a nozzle of a rocket motor gets clogged.)

You could attach a real explosive to the APCP and detonate the explosive. All that would happen is that the APCP will break up. It won't explode. (NASA tested this for the Shuttle's SRBs and, unfortunately, demonstrated it for real after the Challenger accident.)

Possibly, you could grind it up, but it wouldn't be rocket propellant any more. That would be like saying aluminum is an explosive because aluminum powder is.

-- Roger
Click to expand...

I don't know how you dispose of propellant grains, but when we disposed of excess propellant at work,many hundreds of pounds of APCP. we lit it on the burning grounds and generated an huge fire and a giant cloud of white smoke. It burned quite nicely thank you very much and did not go out.

When we disposed of actual propellant grains we did it by splitting the motor case with a shaped charge to render the motor non-propulsive. with the nozzle removed of course, and let it burn to completion in an open pit. The motor in that case does not extinguish but burns to completion, albeit at a lower burn rate, due to lower pressure, that what one sees in a motor firing.

If you want to create what an amateur would certainly call an explosion, though not a ture detonation, you only need to rupture the case while under pressure and thereby fracture the grain. The result is a huge increase in surface area, a massive generation of gas, and destruction of most nearby structure.

Or you can have an accident while mixing the propellant and have an ignition in the mixer. The result of that is blow the roof off the building (they are designed to do that and have extraordinarily thick concrete walls surrounded by sand) and send a rather large fireball skyward with an associated very lound noise, that again most amateurs would call an explosion.

Now these are not full Chapman Jouget detonations, but people can and have been killed by these non-explosions. A mixer explosion is what put United Technologies out of the solid rocket business, and a second accident wth that propellant killed a contract maintenance worker who was working on the damaged mixer.

Once again, people who think these propellants are innocous don't know what they are talking about and are dangerous to themselves and those around them.
 
You must log in or register to reply here.

Back
Top Bottom