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balsaeater -> RE: Concentrate for use with nitro??? (5/3/2008 10:04:41 AM)
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quote:
ORIGINAL: downunder
From what I recall, pure nitro can become shock sensitive over time so a dye is put into it which can detect it and changes colour (maybe something like from purple to yellow) but a very small amount of impurity such as methanol eliminates the shock sensitivity.
...edit..
Iso Propyl Nitrate (IPN) is also shock sensitive and when used as a raw fuel all pipe connections had to go from a small to a large connection or the flow could set up a compression which could set it off (it's a mono propellant). I used to have a gallon can of it and I was always very careful not to drop it but I think I was being overly cautious :D.
Re: downunder
Thanks for the info about that fuel ingredient Iso Propyl Nitrate.
It looks like this might be all or some of the concentrate supplied from the USA Hot cars nitro suppliers
I recall some of the model plane fuel formulas for the tank sized limited fuel competitions control line planes from late 50's to early 60's era included lots of extra components seldom included today such as 5% gasoline 5 % Iso Propyl Nitrate 5% nitromethane and some sorta shoe polish stuff
From the specs of Iso Propyl Nitrate available on line where best I can tell the flame wave front is marginally faster than nitromethane and it has a slow wave flame front more similar to Nitromethane than the rapid flame wave front from methanol or gasoline and a low oxygen requirement to burn like Nitro methane it would make sense to include a few % of this fuel
Best I can figure the methanol would ignite first followed by the Iso Propyl Nitrate followed buy the nitro methane thereby supplying a longer flame wave front and smoother expansion in the down stroke of the piston
(Feel free to correct me if I got it wrong)
This shock sensitivity element for nitromethane best I can figure is very low risk nearly impossible to produce outside a laboratory conditions.
As a mono propellant the nitromethane in rockets last uses were in ~1947 era and the extreme pressures and forces to make nitro methane be a possible mono propellant or a become a shock sensitive fuel are so extreme to be very difficult to succeed to achieve the correct conditions .
The addition of 1% methanol is often done for shipping nitro methane so supplying 99% nitro methane ensures that shock sensitive conditions can never be obtained (with 1% probably being overkill and as little as 0.5% of other contaminants such as Methanol nitroethane and nitro-propane might achieve the same results and 100% pure nitro methane is nearly impossible to archive shock sensitivity)
I suspect the Iso Propyl Nitrate will be similar nearly impossible to achieve shock sensitivity except in the laboratory
I suspect the concentrate will be Iso Propyl Nitrate with some unknown % of methanol fuel combined
But if others know different let me know
I suspect the drag car racing fraternity from the 1960 to 1980 era would know for sure what is the concentrate
I supplied some links for others who might know more chemical stuff than I do
Heavy tecky stuff so most will opt to skip what is below this point or just skim the high points
http://en.wikipedia.org/wiki/Isopropyl_nitrate
quote:
ORIGINAL: en.wikipedia.org
quote from wiki below
"
Isopropyl nitrate
From Wikipedia, the free encyclopedia
Isopropyl nitrate (IPN, 2-propyl nitrate) is a coloreless liquid monopropellant. It is used as a diesel cetane improver. IPN is a low-sensitivity explosive, with a detonation velocity of approximately 5400 m/s.
Isopropyl nitrate was previously used in a jet engine starting system, primarily by the RAF, and was known as AVPIN. It has also been used as a fuel for power supply and actuation in guided weapons, notably in the British Royal Navy.[1]"
end quote
http://www.intdetsymp.org/detsymp2002/PaperSubmit/FinalManuscript/pdf/Zhang-131.pdf#search=%22%22isopropyl%20nitrate%22%20IPN%22
quote:
ORIGINAL: intdetsymp.org
Quote of the main points from the paper above
"Conclusions
Nitromethane has been used for a long time as a model for the study of detonation physics in homogeneous liquid explosives.
Although modern diagnostic technology is now allowing some of the details of the reaction zone of NM detonation to be resolved, the very small detonation length scale (ca. 6-15 ns17) still presents a challenge in terms of elucidating the mechanism of detonation.
Liquid isopropyl nitrate (IPN) is considered a practical alternative for fundamental studies of detonation due to its larger detonation length scale which facilitates higher diagnostic resolution.
In the present paper, the detonability of IPN has been investigated, including shock initiation of detonation and determination of the critical diameter in low impedance PVC tubes.
Two modes of shock initiation of detonation have been observed: direct initiation of detonation, and SDT with a build-up or onset process
involving detonation in the shock precompressed medium.
While the SDT process is similar to that for NM reported in the literature, the reaction thermal energy in the precompressed medium is
much lower than that observed for NM. The SDT process, from the onset of detonation, through the overdriven mode, and finally to C-J detonation, occurs in a transition distance of about 10-15 mm near the critical shock pressure. Limited data for the initial shock pressure versus the time of onset of detonation and the catch-up time have beenobtained.
The critical shock initiation pressure is estimated to be in the range of 7-8.5 GPa at
0±5 °C.
The critical diameter for neat IPN was found to exceed 310 mm at 16 °C in a low impedance PVC tube. Thus, the critical diameter
for IPN is at least one order of magnitude larger than that for NM."
end quote
EDIT extra info for the avaition version of Isopropyl nitrate AVIPN a small quote
http://www.airliners.net/aviation-forums/tech_ops/read.main/164215/
quote:
ORIGINAL: www.airliners.net
The latter (early) marks, PR7, E15, T17, T22 had 3 per engine, 2 as spares. The last mark, PR9, used a really nasty explosive fuel called AVPIN, which was volatile in the extreme. One of our jeeps carrying the stuff through a small town, fortunately in an unpopulated area, caught fire spontaneously, the driver bailed, and the resultant conflagration melted the concrete of the sidewalk. You can imagine the effect this had on the local populous - we were thereafter banned from transporting it through residential areas.
balsaeater
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