6 ms·

JP-7

59 points by win66 6y ago

justin66 6y ago
"Manufacturing several hundred thousand gallons of the new fuel required the petroleum byproducts Shell normally used to make its Flit insecticide, causing a nationwide shortage of that product that year."
- oasisbob 6y ago
  Can anyone verify this claim? It sounds too good to be true. According to Wikipedia, FLIT was a product and large consumer-facing brand of Standard Oil, not Shell.
  - throwaway0a5e 6y ago
    "According to one source, some raw material (possibly the solvent) used for the production of FLIT was similar to that used for LF-1A fuel for the Lockheed U-2 high altitude reconnaissance aircraft, causing a nationwide shortage of bug spray in 1955. Fuel LF-1A was produced by Shell.[6]" https://en.wikipedia.org/wiki/FLIT https://en.wikipedia.org/wiki/FLIT The citation is a book source and it's a book I don't own I can't vouch for the legitimacy.
  - justin66 6y ago
    It's discussed in Ben Rich's excellent memoir, Skunk Works. https://www.google.com/books/edition/Skunk_Works/oL4bHPIt7XIC?hl=en&gbpv=1&dq=ben%20rich%20skunk%20works&pg=PT86&printsec=frontcover&bsq=flit https://www.google.com/books/edition/Skunk_Works/oL4bHPIt7XI...
  - refurb 6y ago
    I can’t verify that exact claim, but as a chemist, it wouldn’t be surprising. Pesticides are mostly organic (carbon containing) compounds and oil is often used as feedstock. So I could see some key starting material for the pesticide being diverted to make a fuel component.
dmurray 6y ago
It's crazy to me that once they had this high-performance jet fuel, they also used it as a coolant and as hydraulic fluid. I guess the main requirement for the latter two purposes is that it doesn't break down at really high temperatures. The jet fuel needs to be stable at high temperatures too (additionally, you need to be able to burn it to make the engine go) so once you put all this research into finding the right jet fuel you have a liquid that will do OK on the other jobs. Edit: and also it was used for lubrication! Good fuels definitely do not necessarily make good lubricants...it must just be really hard to find anything with the right thermal stability.
- iggldiggl 6y ago
  The F-1 rocket engine on the first stage of the Saturn V used a similar arrangement, with the fuel also doing double duty as hydraulic fluid, coolant and lubricant.
  - 2trill2spill 6y ago
    That's pretty standard on most liquid propellant rocket engines.
- throwaway0a5e 6y ago
  > they also used it as a coolant and as hydraulic fluid. Potentially a much smaller headache than pumping one or two more fluids around inside a jet engine and keeping them from breaking down. The jet fuel only needs to not break down for a single pass through the engine. A closed lube or cooling system would need to not break down for multiple passes (i.e. much longer duration at high temperature). >it must just be really hard to find anything with the right thermal stability. A total loss lubrication system doesn't need to be actively cooled (assuming your lubricant input is of suitable temperature) which saves a ton of weight and complexity which is why rocket and jet engines often use the fuel as a lubricant.
  - masklinn 6y ago
    FWIW JP-7 was not the only hydraulic fluid, it was only used as hydraulic fluid in a few places where that was convenient, or possibly where they'd have needed a different hydraulic fluid due to the temperature.
pram 6y ago
I was an inflight-refueling technician in the USAF and there was a variant of the tanker (KC-135T) that had isolated tanks to specifically carry this stuff, for refueling an SR-71. Sadly that was before my time. A neat little factoid tho, I guess.
- savoytruffle 6y ago
  Wikipedia indicates it was originally KC-135Q with the unique fuel system (which separates the exotic SR-71 fuel payload from the typical fuel to fly the refueling plane). KC-135T was the re-engined variant using modernized engines like the rest of the fleet.
The_rationalist 6y ago
So this state of the art technology is no longer used for newer jets?
- throwanem 6y ago
  State of the art for the late 50s. Most jets then and now don't operate in regimes where a fuel like this would be necessary.
- scoopertrooper 6y ago
  The fuel was formulated to meet the engineering requirements of a very particular product that was rendered outmoded by developments in satellite and UAV technology.
aduitsis 6y ago
I've read many years ago that in low temperatures, the SR-71 was prone to leaking fuel while in its hangar. But that was not dangerous because JP-7 won't catch flame without TEB. EDIT: oh yes https://theaviationgeekclub.com/the-story-of-the-sr-71-blackbird-that-slid-on-jp7-fuel-residue-while-taxing-into-kadena-hangar/ https://theaviationgeekclub.com/the-story-of-the-sr-71-black...
- win66 6y ago
  An SR-71 video that gives more context https://youtu.be/dG6gnJc6XeU https://youtu.be/dG6gnJc6XeU
- phlipski 6y ago
  The SR-71 fuel tanks didn't fully seal until the plane was at cruising speed. The heat on the airframe tightened up the tanks. https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird If ever in Washington D.C. I highly recommend the Udvar-Hazy Center at Dulles airport. There is an SR-71 on display there (along with just about every other important plane in US aviation history) that you can walk right up to. It's surprisingly small IMO.
  - Theodores 6y ago
    Not if you are a child and never meet your heroes as a grown-up!
  - op00to 6y ago
    Funny, I saw the SR71 at Udvar-Hazy, and thought it was HUGE!
  - 0xffff2 6y ago
    Haven't seen the one in DC, but I've been within arms reach of one of the old NASA SR-71's that's on display (not accessible to the public unfortunately) several times. "Small" is just about the last word I would have ever used to describe it.
- cbm-vic-20 6y ago
brazzy 6y ago
> However, very high skin temperatures are generated at this speed due to friction with the air. I remember reading somewhere that this is a common misconception and that most of the heat is generated not by friction but by air compression. But that may have been about the Space Shuttle re-entry, which has considerably higher speeds.
IgorPartola 6y ago
Yeah but how does it compare to Skinny Fuel?
wil421 6y ago
They used two massive Buick V8s to get the turbines started. They eventually switched to Chevy V8s. Another person commented about fuel leaking, it must have been a sight to watch one start up. https://youtu.be/JjdyQpEUYzI https://youtu.be/JjdyQpEUYzI
- dsb5 6y ago
  About 2:42 in this video you can hear the side by side V8's revving up and then the J58's whirl. https://www.youtube.com/watch?v=nFO--wzFfUs https://www.youtube.com/watch?v=nFO--wzFfUs

59 points by win66 6y ago

"Manufacturing several hundred thousand gallons of the new fuel required the petroleum byproducts Shell normally used to make its Flit insecticide, causing a nationwide shortage of that product that year."

oasisbob 6y ago
Can anyone verify this claim? It sounds too good to be true. According to Wikipedia, FLIT was a product and large consumer-facing brand of Standard Oil, not Shell.
- throwaway0a5e 6y ago
  "According to one source, some raw material (possibly the solvent) used for the production of FLIT was similar to that used for LF-1A fuel for the Lockheed U-2 high altitude reconnaissance aircraft, causing a nationwide shortage of bug spray in 1955. Fuel LF-1A was produced by Shell.[6]" https://en.wikipedia.org/wiki/FLIT https://en.wikipedia.org/wiki/FLIT The citation is a book source and it's a book I don't own I can't vouch for the legitimacy.
- justin66 6y ago
  It's discussed in Ben Rich's excellent memoir, Skunk Works. https://www.google.com/books/edition/Skunk_Works/oL4bHPIt7XIC?hl=en&gbpv=1&dq=ben%20rich%20skunk%20works&pg=PT86&printsec=frontcover&bsq=flit https://www.google.com/books/edition/Skunk_Works/oL4bHPIt7XI...
- refurb 6y ago
  I can’t verify that exact claim, but as a chemist, it wouldn’t be surprising. Pesticides are mostly organic (carbon containing) compounds and oil is often used as feedstock. So I could see some key starting material for the pesticide being diverted to make a fuel component.

dmurray 6y ago

It's crazy to me that once they had this high-performance jet fuel, they also used it as a coolant and as hydraulic fluid. I guess the main requirement for the latter two purposes is that it doesn't break down at really high temperatures. The jet fuel needs to be stable at high temperatures too (additionally, you need to be able to burn it to make the engine go) so once you put all this research into finding the right jet fuel you have a liquid that will do OK on the other jobs. Edit: and also it was used for lubrication! Good fuels definitely do not necessarily make good lubricants...it must just be really hard to find anything with the right thermal stability.

iggldiggl 6y ago
The F-1 rocket engine on the first stage of the Saturn V used a similar arrangement, with the fuel also doing double duty as hydraulic fluid, coolant and lubricant.
- 2trill2spill 6y ago
  That's pretty standard on most liquid propellant rocket engines.
throwaway0a5e 6y ago
> they also used it as a coolant and as hydraulic fluid. Potentially a much smaller headache than pumping one or two more fluids around inside a jet engine and keeping them from breaking down. The jet fuel only needs to not break down for a single pass through the engine. A closed lube or cooling system would need to not break down for multiple passes (i.e. much longer duration at high temperature). >it must just be really hard to find anything with the right thermal stability. A total loss lubrication system doesn't need to be actively cooled (assuming your lubricant input is of suitable temperature) which saves a ton of weight and complexity which is why rocket and jet engines often use the fuel as a lubricant.
- masklinn 6y ago
  FWIW JP-7 was not the only hydraulic fluid, it was only used as hydraulic fluid in a few places where that was convenient, or possibly where they'd have needed a different hydraulic fluid due to the temperature.

pram 6y ago

I was an inflight-refueling technician in the USAF and there was a variant of the tanker (KC-135T) that had isolated tanks to specifically carry this stuff, for refueling an SR-71. Sadly that was before my time. A neat little factoid tho, I guess.

savoytruffle 6y ago
Wikipedia indicates it was originally KC-135Q with the unique fuel system (which separates the exotic SR-71 fuel payload from the typical fuel to fly the refueling plane). KC-135T was the re-engined variant using modernized engines like the rest of the fleet.

The_rationalist 6y ago

So this state of the art technology is no longer used for newer jets?

throwanem 6y ago
State of the art for the late 50s. Most jets then and now don't operate in regimes where a fuel like this would be necessary.
scoopertrooper 6y ago
The fuel was formulated to meet the engineering requirements of a very particular product that was rendered outmoded by developments in satellite and UAV technology.

aduitsis 6y ago

I've read many years ago that in low temperatures, the SR-71 was prone to leaking fuel while in its hangar. But that was not dangerous because JP-7 won't catch flame without TEB. EDIT: oh yes https://theaviationgeekclub.com/the-story-of-the-sr-71-blackbird-that-slid-on-jp7-fuel-residue-while-taxing-into-kadena-hangar/ https://theaviationgeekclub.com/the-story-of-the-sr-71-black...

win66 6y ago
An SR-71 video that gives more context https://youtu.be/dG6gnJc6XeU https://youtu.be/dG6gnJc6XeU
phlipski 6y ago
The SR-71 fuel tanks didn't fully seal until the plane was at cruising speed. The heat on the airframe tightened up the tanks. https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird If ever in Washington D.C. I highly recommend the Udvar-Hazy Center at Dulles airport. There is an SR-71 on display there (along with just about every other important plane in US aviation history) that you can walk right up to. It's surprisingly small IMO.
- Theodores 6y ago
  Not if you are a child and never meet your heroes as a grown-up!
- op00to 6y ago
  Funny, I saw the SR71 at Udvar-Hazy, and thought it was HUGE!
- 0xffff2 6y ago
  Haven't seen the one in DC, but I've been within arms reach of one of the old NASA SR-71's that's on display (not accessible to the public unfortunately) several times. "Small" is just about the last word I would have ever used to describe it.
cbm-vic-20 6y ago

brazzy 6y ago

> However, very high skin temperatures are generated at this speed due to friction with the air. I remember reading somewhere that this is a common misconception and that most of the heat is generated not by friction but by air compression. But that may have been about the Space Shuttle re-entry, which has considerably higher speeds.

IgorPartola 6y ago

Yeah but how does it compare to Skinny Fuel?

wil421 6y ago

They used two massive Buick V8s to get the turbines started. They eventually switched to Chevy V8s. Another person commented about fuel leaking, it must have been a sight to watch one start up. https://youtu.be/JjdyQpEUYzI https://youtu.be/JjdyQpEUYzI

dsb5 6y ago
About 2:42 in this video you can hear the side by side V8's revving up and then the J58's whirl. https://www.youtube.com/watch?v=nFO--wzFfUs https://www.youtube.com/watch?v=nFO--wzFfUs