The Engine Option

by HPA · December 19, 2011

Frantic Fueling Part II

By Hank Gibson, CFI, CFII, MEI

Last week, I discussed changing the type of fuel we’re burning in our engines in order to save some money. This week, I will discuss changing the type of engine entirely. Gasp. You mean not running a piston reciprocating engine in our general aviation aircraft? Precisely. (Unless otherwise noted, all information and quotes are from Justin Cunningham’s 2006 article, “Rotary Comes Around Again” featured in Professional Engineering magazine).

A company out of Geneva, Switzerland by the name of Mistral Engines is in the process of putting a 300 horsepower rotary engine on the aircraft engine market. Going to a rotary engine would “dramatically improve reliability and offer a superior power-to-weight ratio.” In a rotary engine, there is a significant decrease in the number of moving parts. A typical recip engine contains valves, camshafts, connecting rods, pistons, push rods, rocker arms, to name a few. A rotary doesn’t contain any of these. The simple concept is an “eccentric shaft” (instead of a crankshaft) that the rotor is attached to which rotates around, covering and uncovering the intake and exhaust ports, turning the eccentric shaft in the process.

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This would by far decrease the amount of wear and tear on the engine with so few moving parts. Mistral is in the process of getting their 300 horsepower engine certified by the FAA. According to their, the company states the goal of a 3,000 hour TBO, which with the rotary concept is totally feasible.

The other really handy thing about the Mistral Engine is the flexibility when it comes to fuel. Gordon Anderson, Mistral’s chief engineer, made the claim that with their rotary engine, fuel burn could be dropped by as much as 25% compared to conventional piston engines. In addition, Mistral took things a step further with options when considering fuel. Not only can the Mistral engine be run off of Avgas, but autogas can also be used. As all you heavy footed, land dwellers have learned, autogas is cheaper than Avgas. Yay for saving money!

Most new engine arrangements are equipped with Fully Automated Digital Engine Control (FADEC) and Mistral is no different. Because of this, Anderson claims that “You can switch between fuels, or mix them in any proportion, with no change to your engine or settings.” Mistrals are also liquid cooled, reducing the likelihood of shock cooling on descents, plus increasing engine life due to more even engine operating temperatures.

Well, I’m sold. How about you? Lets go load up that new Arrow we just bought with one of those fancy DeltaHawk’s or Mistral engines. Unfortunately, as previously stated, we’re still waiting on the FAA to get their act together and certify these things (though, at the time of this writing, according to their, the FAA was in the process of certificating the 300 HP G-300 engine with the expected completion to be sometime next year). When they do, we’ll all be going farther for less and enjoying the skies a whole lot more.

Until then, we’ll lean that mixture out just a little bit more and pull that throttle back a little farther on those descents, all in an effort to save a few coins on the Avgas in order to pay the auto gas bill, too. Am I the only one who picks airports based on their fuel costs? Those who don’t care about money pick based on FBOs or the fanciness of the crew cars. Me? I’d rather have Waynette and her few remaining teeth tell me how to get to the local burger joint while giving me a wink on the way out if that saves me money on my fuel bill. As long as I don’t catch something in the ground beef, it was well worth the trip.

How it Started

One of my best friends in high school, (Doug Gray) was a private pilot. He offered to take me up for a flight in a 1967 Cessna 150, N6228S. We took off from Calhoun, Georgia, and he took me on a scenic tour of the area, I was hooked. I later found out that my English teacher, (Jan Haluska) was also a flight instructor and the school was offering a ground school course the next year, which he taught, along with flight training with the goal of becoming a private pilot. I managed to talk my dad into funding the training, at the time the total cost was right around $500. Cessna 150 rental rates where $12 an hour, and the 172 we used for cross country was $15 an hour including fuel.

Training Begins

It started August of 1977. The fall semester rolls around, and I am enrolled in ground school, and if memory serves me, we met twice a week. First came the paperwork for my student pilot certificate, which at the time was included with the 3rd class medical. I loved ground school, especially learning navigation, plotting courses on the sectional, again this was before iPads and GPS, so we did a lot of dead reckoning and VOR navigation for cross countries. At the end of the course, I made an 83% on the Private Pilot written exam, remember this was before we had the question-and-answer books that on future test I would consume before taking a written.

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The fun really began on August 22, 1977, it was my first flight. To my surprise we used the same Cessna 150, N6228S that my friend Doug Gray had taken me for a ride in. The Cessna 150 had a standard VFR instrument panel, with one NAV/COM, and one VOR CDI. No intercom, so no headset, at the time I didn’t know what I was missing. I didn’t get my first headset until I started my instrument training in 2003. I was a big guy, I was 6’ 4” and weighed 245 lbs. but I do not remember being uncomfortable in the 150 even with the instructor in the right seat.

First flight lasted .8 hours, and we accomplished orentation, shallow turns, stability, and effects of flight controls. Over the next few months we added steep 720’s, slow flight, stalls, turns around a point, S-turns, emergencies, landings, (short field, soft field and normal).


At this point I want to talk about a training experience that still stands out. We were close to solo and were practicing takeoffs and landings. Turning base to final Jan got very upset at the way I was cross controlling the aircraft. Cross control is when you are in, say a left turn, and use opposite rudder to line the nose up with the runway. So, he had me depart the pattern and head east to the practice area, and climbing up to 5500 feet MSL, he had me slow down to just above stalling speed, start a left shallow turn and add right rudder. As the airplane stalled I had the strangest sensation, no roller coaster has ever come close, instead of blue sky in the windscreen I was looking at brown ground, and as far as I could tell we were upside down, through the terror of the moment Jan talked me out of the spin, controls neutral, oposite rudder, pull slowly out of the dive. As we leveled off he asked me what altitude we were at, as I remember it was around 2,800 feet MSL. Then he asked me what would happen if I experenced this on base to final in the traffic pattern. The answer was obvious, I would be a pile of wreckage off the end of the runway with a very short-lived aviation career. Needless to say this cured my cross-control tendencies.

Another training event the sticks out in my mind was the first time we did takeoffs and landings at the High School runway. The runway was 1,500 feet long, not sure of the width, but it seems like we had about 5 feet on each side of the wheels when on the center line of the runway. Landing from the south you also had to go between a cutout in the trees to be able to stop in time on the runway. After getting confortable landing here every runway since seemed huge. I remember landing at Chattanooga (KCHA) on a night cross country and commenting to Jan, that I felt like I could of landed sideways on the runway, it felt that large.

Very soon after this I started wearing old shirts to all my flight lessons, the reason for this occurred on February 8, 1978. The lesson that day was stalls, takeoffs and Landing. As we were taxing back in Jan told me it was time for my first solo. I was very excited, and after some last minute advice from Jan, including watch for floating on landing the plane will be light with him not in the right seat, complete 3 takeoffs and landings to a full stop. It was a blast, and at the end of my shirt was shorter in the back because Jan cut the tail out of it signed and dated my solo [an aviation tradition]. Total flight time accumulated on the day of my solo was 18.1 hours. I was now officially a pilot with solo priveleges.

In my next article I start cross country training, when Jan decided that it would be best accomplished this in the 172. Checking out in N5970R was like moving into a 747, this started a love affair with one of my faviriote planes to date. Since this time I have flown over 900 hours in many different models of the 172 and feel like I am stepping into an old friend every time.

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