Single Engine Jet Aircraft

First, if we build an aircraft propelled by a jet rather than a turbo prop, we want to harness the velocity capability of a jet. In order to do this, we will probably want arrowed blades and a relatively small blade area for the jet in comparison to a reciprocating or turbo-prop aircraft.

Smaller, arrowed blades will increase land speed compared to aircraft with large rectilinear blades. When we look at the Piper and Pilatus single engine turbo-props we see that they have big flat blades - actually some very big blades. On the other hand, the concept behind this is that if the single turbo prop engine fails, the large, straight blade would deliver a good L/D to find a good airfield or even an effective airfield.

A large aerofoil would also mean a much lower land rate, which would mean less take-off and land procedures, or the outcome would be less loss and less chance of injuries due to the lower touchdown time. The Pilatus PC-12 Landewalze amounts to 985 foot. The Piper improves the MeridianOkay, an attempt with large blades that has proven its worth in slow turbo-props.

But that won't work on those planes with smaller arrowed blades. Smaller, curved blades allow a jet to land at velocities in the 90 to 120 milliph region instead of 65 to 85 milliph in a turbo prop. Thus the jet needs two thrusters instead of one, because the impact of the loss of a single thruster becomes much more serious - the smaller wing means less glide and glide times, the touchdown becomes MUCH quicker and more thrilling, and the impact is less viable.

We also see that single-engine large-wing turbo-props can use smaller take-off and runway lengths than a single- or twin-engine small-wing jet could use. Whereas an engine is the most costly element besides the aircraft chassis itself, the additional costs will be in the range of 15-24% of the total aircraft.

Having two power plants does not therefore provide an insuperable additional boost in costs - and having just one power plant does not provide enough economic benefit to solve the problem with single-engine power plants. So if you only have one engine, where are you going? When it is above the hull (see images by Gary Stein), you have a genuine service that makes trouble when the engine is needed and an service or work.

Place it under the hull and the engine will absorb all possible stones, dirt and debris during take-off and land. No good, especially since we depend on this one engine. Directing the air flow through the body makes the cell more costly and heavy and still carries a potential hazard of debris.

Using two motors, one on each side of the hull, most of these issues and cost go away, even the servicing is simpler.