aircraft performance - Why does the Piper Cherokee (PA-28-140) engine have such low horsepower despite the very large displacement?

I'm sure this question could apply to many other plane engines, but specifically I'm looking at the Piper Cherokee PA-28-140.Surprisingly, it appears that the engine used, the Lycoming O-320, has ~320 cubic inches of displacement but only puts out 150hp.When comparing the horsepower per cubic inch of displacement (CID), the ratio is quite low. We have the technology (and already used it in vehicles in the 50's, 60's etc.) to achieve a better efficiency than that. Why is this engine (and perhaps other models) so inefficient?...Read more

Do takeoff (or other) performance calculations for jet aircraft take into account the type of fuel being used?

Jet aircraft can use any of a number of different fuels:1Jet A-1 is a straight kerosene, not that much different from what you used to buy for committing arson fuelling portable space heaters.JP-8 is Jet A-1 with the military’s stamp of approval.Jet A, used almost exclusively in the United States (because ‘MURICA) and only available at a few non-US airports (most of them in Canada), is Jet A-1 with a slightly higher freezing point.2Jet B is a mixture of 30% Jet A-1 and 70% unleaded gasoline, used in climates where Jet A-1 would freeze into a so...Read more

aircraft performance - What is the average time and distance needed to reach cruising height?

I am trying to compare trains with airplanes and the distances where taking a train is more viable than an airplane. I guess this would depend on the type of plane, but the Airbus 320 seems like a common enough plane in Europe so I have something along that type in mind.As far as I know, it would be a good model for airplanes to separate the takeoff and landing phase, where they cover less ground and does take appreciable time on shorter hauls and the cruising phase. I found average speed for the latter but I don't know how much time takeoff ta...Read more

aircraft performance - Could this helicopter's body be a flying wing?

This question: Could a helicopter fly like a plane this way? asks if a helicopter can turn sideways using additional wings to tip forward to allow the rotor blades to act as a propeller. The tail-setter and other types of planes came up as answers. Similar to the tile Setter their first function of this aircraft would it be to hover then to fly as a plane. Would this model helicopter with a body shaped of a flying wing be able to fly at a 90 degree angle and at a 90 degree twist transferring lift from the rotor blades to the body? I have sketch...Read more

aircraft performance - Why was Energy Maneuverability theory not applied to the F-14?

In John Boyd's (declassified) 1966 Energy Maneuverability [PDF] report, studies were done on the F-4 and on the MiG-21 and those studies were applied to the F-15, F-16 and F-18. My questions:Why wasn't this theory applied to the F-14? Was this due to the fact that it was a carrier-based aircraft? Or did it have to do with the variable sweep wings that would change how the energy bleed changed with changes in the sweep angles at different speed?The F-14 was developed well before the theory of Energy Maneuverability was published, but improvement...Read more

aircraft performance - Is (L/D)max achieved at a specific speed or AOA?

I'm little bit confused about the (L/D)max.So I've read this blog: the author shows this graph: So if I understand it correctly the (L/D)max is at the intersection of parasitical drag and lift-induced drag. Thus, at the point which has the minimum total amount of drag. Which is achieved at a specific speed. Skybrary states the following: The maximum lift/drag ratio occurs at one specific CL (Lift Coefficient) and AOA (Angle of Attack (AOA)),_For...Read more