AVmail: July 21, 2003

Reader mail this week about twin-engine safety, UAVs, new GA engines and more.


Why Twins Crash

I very much enjoyed the recent article, and agree that maintenance on older twins must be one of the bigger safety factors. I was interested in the author’s comments about practicing asymmetric go-arounds.Here in the U.K. the CAA standard for the initial instrument rating and its annual renewal requires you, typically, to go through an engine-out drill following a go-around on the ILS (at around 400 feet AGL, once cleaned up and established in the climb). The simulated engine failure is given a zero thrust once the drill is completed and you are then expected to fly the SID, a hold, and a procedure non-precision asymmetric to minimums. At minimums you are expected to descend to commital altitude (typically 300 feet AGL), execute an asymmetric go-around going to circling minimums, and then fly a circling approach and land. Fortunately the U.K. has low density altitude but a tired Seneca struggles through this routine. Robert Lough

Strobe Lights Missing

Piseco Airport (K09) is the only airport in the middle of the Adirondacks, and in Hamilton County, N.Y. It is owned and operated by the Town of Arietta. It has been without strobes on the east end of the airport since last March, due to the town’s lack of interest in having the strobe lights in good repair and operating. They just need repair. There is no excuse for this. In haze or at night this could be a serious issue.Henry Rogers

Pilot-Optional Airplane

There is a correction that should be made to your July 14 article about Explorer Aircraft and its UAV appearance at AirVenture. The company is not in Australia, its in Jasper, Texas. We are in our 14,000 sq. ft. hangar/office complex where the Explorer line of aircraft will be engineered and assembled. Explorer was originally in Australia and the program was brought to the U.S. in 1999. For your information the prototype 500T is at the AUVSI show in Baltimore this week. There the aircraft will be shown to military and civilian agencies from around the world in its role as an OPV, Optionally Piloted Vehicle.Sam Ketchum
Sales & Marketing
Explorer Aircraft, Inc.

New GA Engine: Changes In The Wind

This week’s AVflash had a remark that the high RPM of the Rotax geared engines (4 to 6000 rpm) raised questions regarding fuel economy. It does: Why aren’t all aircraft engines geared?. Piston engines are most economical around 3 to 5000 rpm, especially if they are diesel. The smaller Rotax 4 cylinder engines are very economical.Graham Singleton

AVweb Responds:

Actually, the smaller Rotax engines are not at all economical. You just don’t notice it because they don’t make much horsepower. The Rotax 912 used in the Diamond Katana has a brake specific fuel consumpion of about 0.43 pounds per horsepower. Some larger Continental engines making much more horsepower have BSFCs in the 0.40 range and can sometimes hit the high 0.30s.

Gearing an aircraft engine has the advantage of lower prop speeds and improved efficiency with larger, slower turning blades. Slower turning blades are quieter, too. But gearing introduces friction, which robs economy. Even if you don’t care about paying for the gas, poor fuel specifics sap range and that can be a deal killer for a new airplane.

Bottom line: The new Bombardier engines may not be as economical as current designs and might even be a little worse.

Paul Bertorelli
Editorial Director

Bernoulli vs. Marconi

Yes, I know it is a hassle dealing with post-9/11 restrictions. And yes, it can be a hassle when Approach Control is too busy to find your flight plan, and passes you off to FSS. However, having said that, I can think of no acceptable excuse for running out of gas while talking on the radio.I did notice, before I retired, that both pilots and air traffic controllers were getting a little sloppy with Expected Approach Clearance times. A bit more attention to this detail might have avoided this accident. Hanging around hoping for a clearance — while your fuel drops below bingo — is a trap that has claimed pilots with a lot more experience than 75 hours.Which brings to mind the value of hangar flying … Unless you feel you will live long enough to survive all possible mistakes.Finally, the phrase is, “I am declaring emergency fuel.” I thought we settled that some years ago after the airliner crashed short of the runway at JFK. There is no stigma. There is stigma if you crash and die or kill people.The fighter pilot’s claim of, “I’d rather die than look bad,” is a joke. They are not words to live by.Jim Selander