Why we use fixed engine for aircraft sizing?

Cost effective

Can be stretched

Can be rubberized

Can provide variable thrust at sizing

Correct Answer : Cost effective

Explanation : Fixed engine is more easily available than a rubber engine. Any existing engine can save millions of dollars which was going to be spend in developing the new engine. However, we cannot stretch it during sizing but they are more cost-effective than the rubber engine.

Recently Updated in Aircraft Design Questions

Rapid oscillations of control surface due to application of the air loads is termed as __________

control surface trim

control surface flutter

control surface span

control surface effectiveness

Correct Answer : Option (B) : control surface flutter

Explanation : Rapid oscillation of control surface is called control surface flutter. This rapid oscillation can tear off the surface or wing/tail itself. This will induces excessive vibration as well. Effectiveness of control surface is measure of how effectively we can control the aircraft.

Following diagram represents ______

fluttered balance

overhorn balance

overhung balance

notched aerodynamic balance

Correct Answer : Option (D) : notched aerodynamic balance

Explaination : Above diagram is showing a typical notched aerodynamic balance. It is also called horn aerodynamic balance. We can reduce the force required for deflecting the control surface. However, it is not suitable for high speed aircrafts.

If a wing has span of 12m. Find the approximated length of the aileron of starboard wing.

2.4m

15m

20m

25m

Correct Answer : Option (A) : 2.4m

Explanation : For a typical wing, ailerons are extended from 50% of span to 90% of span.
Given, Span of wing b=12m. Since we need to find aileron length at one wing we will divide total wing span by 2.
Hence span of starboard wing = 12/2 = 6m.
Length of aileron at starboard wing (right wing) = |difference between 50% and 90% of span|
= |50% of 6m – 90% of 6m| = |0.5*6-0.9*6| = 2.4m.