The GAfuels Blog is written by two private pilots concerned about the future availability of fuels for piston-engine aircraft: Dean Billing, Sisters, Ore., an expert on autogas and ethanol, and Kent Misegades, Cary, N.C., an aerospace engineer, aviation sales rep for U-Fuel, and president of EAA1114.
Few aspects of an aviation event attract greater crowds than an airshow. Growling radial engines, the smooth whine of Merlins and Allisons, screaming unlimited aerobatic planes, and jet-powered trucks/school buses/outhouses are what many people have come to expect in exchange for admission. Imagine though what would happen if leaded avgas suddenly became unavailable, either through environmental, technical or economic reasons. Would airshows acts consist mostly of sailplanes and the lucky few who can afford low-altitude, high thrust jet operations?
While the highest-performance Warbirds powered by water-cooled, high-compression ratio engines such as the Rolls-Royce Merlin and Allison V-1710 need the anti-detonation properties of 100-octane, leaded avgas, many engines in airshow aircraft could run on 91+ octane, ethanol-free autogas with no or little modification. A quick review of the list of engines and airframes covered by Petersen Aviation’s autogas STC reveals a long list of certificated airplanes often seen in airshows, for instance:
- Beechcraft – D17/UC43 Staggerwing, AT11/C45/D18 Twin Beech, E33 Aerobatic Bonanza
- Bellanca/Champion – Citabria
- Boeing – Stearman PT13/PT17/PT18/N2S2/etc.
- Cessna – L19/O1 Bird Dog
- de Havilland – DHC2 Beaver
- Douglas – DC3
- Fairchild – Model 24
- Grumman – G21 Goose, G164 Ag-Cat
- Globe (Temco) – GC-1A & GC-1B Swift
- Great Lakes – 2T-1A-1 Sport Trainer
- North American – BC-1/AT-6/SNJ-2 Texan/Harvard
- Piper – L4A Grasshopper
- Ryan – ST-3KR/PT-22 Recruit
- Spartan – SW/UC-71 Executive
- Stinson – SR/AT19 Reliant
- Waco – UPF7/etc.
(Check Petersen Aviation for exact model number of airframes and engines covered by autogas STCs).
Many experimental-category aircraft use engines that may be run on autogas, for instance those powered by Lycoming O-320 and O-360 series engines. One of the more popular new airshow acts are formation teams using various RV designs from Van’s Aircraft, for instance TeamRV, which is based in Atlanta. Given the popularity of the O-320 and O-360 engines among RV builders, the majority of airplanes in RV formation groups could operate on autogas. The same holds true for popular teams using Boeing Stearmans and North American T-6/SNJ designs. Any warbird licensed in the Experimental category and powered by radial engines from Jacobs (R-755), Kinner (R-5, R-55, R-56), and Pratt & Whitney (R-985, R-1340, R-1830) could potentially operate on autogas (contact Petersen Aviation for details).
A large number of foreign-built warbirds and aerobatic aircraft are powered by the venerable Vedeneyev M-14P radial engine, designed to operate on unleaded 91+ octane autogas, such as Yak 50/52/55, Sukhoi SU-26, Pitts Model 12, and the new Bear 360. The Italian motorsports engine maker EPA Power offers a version of the Rotax 912 engine for light aerobatic aircraft such as the Alpi 330 SC, Dallair FR-01 and Millenium Master.
With the recent news of Lycoming’s FADEC-controlled iE2 series of engines being able to run on autogas, designers of high-performance aerobatic aircraft have a potential unleaded avgas option today. For instance, the awesome MX2 Aircraft from MX Aircraft of Wilkesboro, North Carolina, used by many Red Bull pilots, as well as by airshow notables such as Greg Poe and Gary Ward, would make good use of Lycoming’s ethanol-free autogas-burning, 350 hp TEO-540-A1A engine, also selected for the new Tecnam 11-place P2012 Traveller twin.
Would the disappearance of leaded avgas mean the end of Warbirds and airshows? Not hardly. More probable is a gradual transition to autogas for all but the most demanding Warbirds, for which a small supply of “boutique” leaded fuel is likely to exist for many years to come. Hopefully, airshow spectators will never notice the difference, but operators of these wonderful aircraft will enjoy the savings in fuel costs with the switch to autogas.
Who will be the first to organize a lead-free airshow, which would surely qualify as a “green” event, something the public these days seems to desire. General Aviation needs all the friends it can get, so why not?