[BUG] Aero Commander 500/520 Insufficent Power.

[DrSuperGood]

The Aero Commander 500 (mail) and Aero Commander 520 have insufficient power to reach their maximum speed. They need either a slower maximum speed, more power or some gearing.

Edit: This applies to a lot of aircraft. Here is a small list.
Aero Commander 520
Beechcraft Model 18
Aero Commander 680 "Courser"
Fokker F27-100 "Friendship"
Fokker F27-200 "Friendship"
Fokker F27-500 "Friendship"
Fokker F27-500 "Friendship" (high density)
Sud Aviation SE 210 Super Caravelle 10B
Sud Aviation SE 210 Super Caravelle 10B (high denisty)
Aero Commander 500 (mail)
Beechcraft Model 18 (mail)
Fokker F27-100 "Friendship" (mail)

[Spenk009]

Is this empty or full?

[DrSuperGood]

Is this empty or full?

Both. They physically cannot reach their top speed at all. They just do not have the power to overcome Extended's drag physics to reach their max speeds. This might not even be a complete list, this was just what is (was) available at the moment on the bridgewater brunel server.

Since extended bases power on real life numbers this is where gearing comes into play to compensate without fudging the power number. This does not seem to be a problem for jet engine based aircraft.

[Spenk009]

I have taken a closer look into this and toyed around with the gearing and tractive effort. What I've done is to adapt the gearing of the Aero Commander 520 and noted the top speeds achieved.

gearing	Vmax
50	139
100	197
150	241
200	278
250	311
300	326

In this case the gearing of 300 would seem appropriate. I have some issues with the acceleration of the high gearing. Here's a recording of the problem. https://i.imgur.com/gMawH1S.mp4

Is this possibly an issue in the code that calculates the acceleration depending on the gearing? The acceleration should reduce as the higher gearing transfers less torque against the resistances. I'm not sure whether this topic then should remain in the thread.

[DrSuperGood]

Is this possibly an issue in the code that calculates the acceleration depending on the gearing? The acceleration should reduce as the higher gearing transfers less torque against the resistances. I'm not sure whether this topic then should remain in the thread.

From what I understand gearing is basically a power multiplier. It is intended to allow one to use realistic power values for vehicles while adapting the simulated power to be appropriate for the desired top speed or acceleration due to differences between simulated physics and real physics.

The issue here is likely due to the inaccuracies of simulated physics. In the case of aircraft one might need functionality to be able to specify a realistic acceleration curve for them during take-off and landing.

[Spenk009]

From what I understand gearing is basically a power multiplier.

I see. Adding a higher rolling_resistance as a resistance test value to combat the gearing increase will then result in a lower top speed while retaining the unrealistic acceleration (linear acceleration = exponential resistance increase).

I wanted to suggest some error in the calculation, but I'm certain these things have been thoroughly researched and tested before me. Reducing the base resistance for aeroplanes and limiting acceleration for all is a suggestion I have, but this is more falsification of factual values and a bit of a hack.

[jamespetts]

Thank you for your report in relation to this, and apologies for not having got around to dealing with at this stage: as will be familiar, it is difficult for me to work on Simutrans-Extended at present owing to the need to replace my computer.

Dealing with this highly complex calibration issue is likely to be extremely time consuming, as it will need exhaustive testing. I did not write the physics engine; this was done by Bernd Gabriel many years ago and I do not know how it works.

In the interim, is anyone able to check what the minimum gear value necessary to allow each of these aircraft to reach their maximum speed is? As Dr. Supergood stated above, the gearing is just a multiplier of power and tractive effort, as in Standard (except that Standard does not have tractive effort), so the name is very misleading.