Hi to the boaters
I think I got some breakthrough in the subject of REVERSE THRUST FOR SHIPS.
I specifically was looking for a solution for boats with a piston engine (boats with turbo props and jet engines don't seem very realistic, do they?).
To me, many changes in the flight dynamics file (aircraft cfg) often looked like trial and error solutions. So i wanted to find out if there was'nt a universal method that could be applied.
Therefore first a small theoretical framework, but as simple as possible (my excuses to people who know much more about this and who'll say that I am oversimplifying):
A piston engine in FSX delivers forces that make a shaft turn in 1 direction only. That movement can not be reversed (i.e. anti clockwise). So reverse thrust does not come from the engine.
On the shaft sits the propellor.
There are 2 kinds of propellors.
A fixed gear propellor that can not create a reverse thrust,
and a constant speed propellor that can.
Why? Because it can feather. This is what happens when you feather a propellor:
https://www.youtube.com/watch?v=eT3Pn6o6DcoSo it can create a reverse thrust, because it can change the angle of attack of the blades in the air or in the water.
Back to FSX:
It is actually rather simple to create a reverse thrust for a ship.
You go to the aircraft CFG file, look for the propeller section and see that you set the following parameters:
propeller_type= 0
beta_max= 65
beta_min= 15
min_gov_rpm= 500
prop_feathering_available= 1
prop_auto_feathering_available= 1
min_rpm_for_feather= 500
beta_feather= -65
prop_reverse_available= 1
minimum_on_ground_beta= 1
minimum_reverse_beta= -14
The rpm values may somewhat vary and also the beta values (feather angles) are not absolute. But I am pretty sure that the reverse beta must be a negative value.
And maybe a propeller with 4 blades works better for a boat, but I don't know for sure.
How do you make this work when piloting?
First F1 and then F2 will not work.
There is a command Cntr+F2, that is often misunderstood. In most literature it says that it reduces the RPM. But in Microsoft literature I found that it actually decreases the propellor beta (angle of attack of the blades), which means that it is the feathering command.
So if you are piloting a ship and want to reverse:
Push F1 first, keep Cntr+F2 down for some seconds, give throttle again and you'll be in reverse.
To return to normal thrust: again push F1, then Cntr+F4 for some seconds and give throttle again.
VoilĂ , problem #1 of the pilotable shipping solved.
Up to the next one: improving the autopilot tracking...
Cheers
Marcel