A jet model seen at the Northwest Regionals in May 2009. Flying Lines photo.
Most of you have probably heard that we most likely will be changing our standard jet fuel formula. It seems that all of a sudden propylene oxide has become very difficult to obtain. The folks at Redmax say they cannot get it anymore. It's probably just another casualty of the days we live in ... another dangerous item that the rank and file have no business having, at least to the powers that be. The last time I bought a quantity of it was about 3 or 4 years ago. At that time the propylene oxide price was similar to nitromethane, but then spiked way up later on.
Some testing has been done and it was found that a mix of 80% alky and 20% nitromethane starts and runs well. Hey, does this sound familiar? Remember back when we went to standard fuel for almost everything to slow things down in the 1990s? The original standard jet fuel formula used MEK (methyl ethel ketone). We quickly found out that while it seemed to work OK in the sport jet engines, it was ultra-critical in the fast engines, and so then we switched over to the alky/prop brew. Nitromethane was tried at the time and found to be acceptable. If nitro was OK back then, how comzit we didn't just use it then????? While perusing some old mags and newsletter from the era I found the answer to that question. When we needed to make the formula change was right in the middle of a nitro shortage, which was a result of a major manufacturing plant going down. Aha!
Let's take a look at the pros and cons of the new mixture: On the negative side your fuel mileage will suffer, probably dropping at least a couple of laps. Early tests show that metering jet sizes on suction feed will go up three or four sizes. You may need to make up a new set. If your lappage is already tight to get your full timed run, then you may have to make up a new tank. Easier said than done with some planes.
On the positive side we will have a fuel that is much easier to obtain. No problemo getting the two components, plus it will be available from Sig on special order. Storage will not be the problem as it was with the propylene oxide, which had a tendency to slowly, or sometimes quickly, dissipate from the blend depending on the quality of the container and ambient temperature. And another nice change ... it will be lots cheaper! Testing has also indicated that so far the speeds produced are slightly slower, so no immediate worry about changing line sizes. And just a guess from this writer, who could be wrong, perhaps the nitro mix will be more forgiving on metering jet sizes. We will see on that one.
*****************************************
Here's a real brief review of speed news for 2009:
The Jim Walker Memorial meet in Portland kicked off the NW speed season with a good entry. The F2D proto event is now well established. At the NW Regionals in Eugene we saw a super entry level owing to lots of speed enthusiasts coming from other regions. Several Regionals records set and one national record toppled. At the September "Bash" in Salem, entry was down but lots of fun was had anyway. The Louie-Louie Team finally got their D working! The All-Proto contest that had been scheduled for earlier in the year was canceled, due to lack of sufficient interest. The concept of a limited event speed contest sounds like a good idea to try, but we need more interested numbers to do so. Also lacking this year was any organized speed activity North of the Oregon border. Would be good to see something up that way again.
-- ZZ
This page was upated November 23, 2009