Chimbu
No, Remoak.
At the instant that thrust is removed the rate of acceleration starts to decrease but actual deceleration starts some period of time later.
If an aircraft is being accelerated at say 10m/sec/sec it doesn't instantly go to -1m/sec/sec but rather experiences an acceleration rate of 9/8/7/6/5/4/3/2/1 m/sec/sec first.
It may FEEL like deceleration but its actually reducing acceleration.
Nope sorry, you are utterly wrong on this. I think maybe you misunderstand the meaning of acceleration - which is defined as a
rate of change, not just a change.
As soon as you remove thrust, the speed may
appear to increase slightly - but the
rate of change is negative (ie a deccelaration). You have alluded to this yourself in the figures you quoted in your post. As acceleration is a vector quantity, as soon as the vector (or rate of change - not just change) starts to reduce, the acceleration becomes negative.
And if you disagree with that, you would need to be able to explain how an object being accelerated can continue to do so when the accelerating force is removed. Inertia doesn't do it; all inertia does is slow the rate of acceleration (or decceleration). Remember, a decrease in the rate of acceleration is actually a decceleration - it is a negative vector.
If you don't believe me, try hanging some fluffy dice from your wet compass. If you accelerate forwards from rest, the fluffy dice will head rearwards - the angle of the string indicating the rate of change. The harder you accelerate, the greater the angle on the string. The proof that the angle of the string is indicating acceleration is that if you stop accelerating and continue moving at a steady speed, the fluffy dice will hang vertically again (ie no angle on the string, therefore no acceleration therefore equilibrium). Going back to our example, if you then remove the power and hit the brakes, the fluffy dice (subject to whatever small inertia they possess) will
immediately start to move forwards. The acceleration (as indicated by the angle of the string) immediately reduces (implying negative acceleration or decceleration). The speed will continue to increase for as long as the string is rearwards of vertical, which is never going to be more than a very small fraction of a second.
Any increase you are seeing on the instruments has more to do with lag in in the system than an actual physical increase in speed.
404 Titan
I’m not sure what aircraft you fly and/or whether it has a full EFIS setup but the last time I was in the sim the Speed Trend arrow on the speed tape of my PFD didn’t go from acceleration to deceleration in an instant. It did exactly as Chimbu Chuckles has stated. The acceleration decreases over time once the power is reduced or removed before the aircraft started to decelerate.
A speed trend arrow is a PREDICTION, not an actual rate change, and isn't reliable in the abort case because the system is simply not set up to measure the extreme velocity change accurately.
ace from space
To be fair, comparing an engine failure in a four engine jet with a two engine turbo prop is not comparing apples with apples.
The same principles apply in a turboprop. Those that don't have a reduced thrust schedule, normally have a thrust augmentation system (ie water meth in the F27 or some J32s).
Besides, a two-engine go-around in the jet is probably just as difficult... ;-)
F.Nose
It depends on the mass of the object and rate of acceleration.
Think of a bullet being fired from a gun. The bullet is initially at rest until a charge is applied and it then accelerates until equilibrium is achieved before starting to decelerate. Thrust is removed the moment the bullet leaves the barrel however at that point it is still accelerating.
The mass of the object is what gives it inertia. Acceleration is itself a rate, so to be pedantic you can't have a rate of acceleration (which would be the rate of the rate of change of velocity).
As mentioned above, acceleration is a vector quantity. As soon as the bullet leaves the barrel, the
velocity may increase slightly (but only slightly), but the
rate of change of velocity (which is what acceleration is) immediately reduces. Think about it - it has to. There is no thrust and lots of drag - the bullet has no choice but to slow down, and more to the point there is no way that the
rate of change of velocity can increase when there is no accelerating force...
Looking at it another way, equilibrium is achieved when thrust=drag. This occurs for a very brief instant at the end of the barrel. After that, only deccelaration is happening.
If you have found a way to get the bullet to accelerate when there is no accelerating force, you have basically invented perpetual motion!