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is a blend of materials. How does each react to normal aviation fuel systems?

A second question relates to costs. For my company, every chemical I buy costs at least $5 per pound. At 6 pounds per gallon, this equates to $30 per gallon for a fuel. With the best will in the world, I can’t see how this can be an economic replacement for avgas or 100LL, which is about $5 a gallon at my local fixed base operator.

My third comment relates to other fuel alternatives. BP and DuPont have been developing a butanol/gasoline blended fuel for quite a while that they call “BioButanol,” produced by fermentation. Here is what they say on the BP America website:

“Laboratory and vehicle assessment of butanol blends greater than 16 percent also have produced favorable test results. The results show that 16 percent high octane butanol blends have the added advantages of vapor pressure behavior and distillation curves comparable to regular gasoline and, unlike 10 percent ethanol, do not phase separate in the presence of water” (my emphasis).

Butanol and its isomers have the advantage of similar energy content to that of gasoline. Since it uses the same process for producing ethanol, just different bugs, the cost is very similar. This assumes that the government subsidy for ethanol also applies to butanol.

My next comment refers to the beneficial effect lead can have on exhaust valve seats. How will the problem of valve seat recession be dealt with if lead is eliminated? Perhaps metallurgy has the answer, but the answers need to be on the table when these questions are dealt with.

Finally, the answer that works for all of us in the drive to remove lead from 100LL may be a compromise. It seems to me that a completely new fuel formulation is risky, however good it looks on paper.

I like the idea of the BP/DuPont butanol to replace ethanol; that solves the phase separation, octane, and energy content problem, and I’m surprised that it has not received more press. The EAA and Petersen supplemental type certificates have a good chance of remaining in force if such a mixture was used.

This critique is meant to be constructive, and I hope that my comments will be taken in that spirit and will lead to healthy debate to find the right answer for all of us. I have no connection to Swift Enterprises, BP, or DuPont, but I have to confess to being a chemist and chemical engineer.

Chris Lowery, EAA 603052

Tracy, California

Your article on fuels was interesting. There is one fuel that is being overlooked. This fuel is high-octane ( 100+), is widely available, and can be stored indefinitely without deterioration. Its closed fuel system prevents contamination, burns so cleanly that oil stays clean after 50 hours of use, is lead-free, has been shown to extend engine life in automotive use, contains more energy per pound than gasoline, and sells for less than one-half the cost of aviation fuel. Modern fuel-injected systems achieve the same power and economy as gasoline. What is this fuel? Propane.

Larry Brooks, EAA 546397

Skiatook, Oklahoma

Great Issue

I recently finished reading the February 2009 edition from cover to cover. I have to say that this was one of the most informative single editions of any aviation periodical I’ve ever read. As a certificated flight instructor, I particularly enjoyed the article “A Flap by Any Other Name…” by Todd Parker.

As the owner of a light piston aircraft running on the increasingly endangered species of 100LL, I found the “Fuels for the Future” article by Jeffrey Decker to be very timely. The updated information on Canadian requirements for 406 MHz emergency locator transmitters was also thought-provoking for a guy who lives and teaches in close proximity to the border.

Great work!

David A. Hamel, EAA 697786

York, Maine

You Missed the GP- 4!

I am presently building a GP- 4 designed by Osprey. This is a plans-built aircraft with a speed of 240 mph and made of wood. This aircraft has won more awards than any you have mentioned in your February 2009 issue (“Building From Plans”). There is not one word of the GP- 4 in the article. I feel this is an aircraft that deserves more acknowledgment than any in your article. The design makes the aircraft qualified for aerobatics as well as a fast trip to any location you desire. The GP- 4 needs more recognition.

Ralph Cristofaro, EAA 529240

Las Cruces, New Mexico

Loved Building From Plans

The “Building From Plans” article in the February issue was a wonderful article, one of the best that I have ever read.

Davisson writes about the fact that “time comes from somewhere” and the trade-off with family time and the need to discuss it with them. Wow. That’s very responsible and mature, something that our society just doesn’t perpetuate very often. Great work!