Can someone please explain to me my plane's TWR chart?

[Regor]

Can someone please explain to me my plane's TWR chart as provided? I used KER to find the TWR in every Mach Number.

 

Here it is:

[FullMetalMachinist]

Not sure why you tagged this as "weird", looks perfectly normal to me. What exactly are you not getting? 

I'm going to go out on a limb and guess that you don't understand why your TWR would change as a function of mach number. The reason is pretty simple. Every air breathing engine has a thrust curve, where the amount of thrust produced (with everything else being equal) changes depending on it's speed. Too slow and there's not much, too fast and you get the same problem. But there is a certain spot for every engine where it will produce optimal thrust. 

Don't ask me to quote hard numbers, but I know that's the case for the game, and I'm pretty sure that's how it works IRL as well. 

[Regor]

I already understand that very well, (in fact I made plane based on this concept), but I do not understand why the curve is so wiggly, as in that it has so many ups and downs. BTW, my plane has 2 whiplashes and 4 wheelsy(s)?

31 minutes ago, FullMetalMachinist said:

Not sure why you tagged this as "weird", looks perfectly normal to me. What exactly are you not getting? 

I'm going to go out on a limb and guess that you don't understand why your TWR would change as a function of mach number. The reason is pretty simple. Every air breathing engine has a thrust curve, where the amount of thrust produced (with everything else being equal) changes depending on it's speed. Too slow and there's not much, too fast and you get the same problem. But there is a certain spot for every engine where it will produce optimal thrust. 

Don't ask me to quote hard numbers, but I know that's the case for the game, and I'm pretty sure that's how it works IRL as well. 

It does work like that IRL as well.

Edited April 12, 2017 by mabdi36

[Reusables]

It's because you're intermixing the two engines. Wheesley is optimized for subsonic flight with maximal thrust on mach 0 and mach 1, and the thrust diminishes quickly over mach 2. On the other hand, whiplash is optimized for mach 3~4. Combining these two thrust 'hill's, you can get the twin-hill shape with a lump on stationary state(Wheesley at Mach 0).

Edited April 12, 2017 by Reusables

[Regor]

10 minutes ago, Abastro said:

It's because you're intermixing the two engines. Wheesley is optimized for subsonic flight with maximal thrust on mach 0 and mach 1, and the thrust diminishes quickly over mach 2. On the other hand, whiplash is optimized for mach 3~4. Combining these two thrust 'hill's, you can get the twin-hill shape with a lump on stationary state(Wheesley at Mach 0).

Thanks!

[AeroGav]

The TWR bandied about in Kerbal Space program are insane.    

In the real world, you're looking at 1.2 to 1 on an F15 or F22 Raptor with a light load.     Concorde with afterburners on was approx. 0.45 to 1,  Boeing 777 with GE90 engines 0.3 to 1 (when not derating to extend engine life, they climb really steep after takeoff),  Tupolev Blackjack bomber (swing wing, mach 2, afterburners) about 0.6 to 1.

Nothing wrong with building huge TWR if you want a fighter/stunt plane/vtol,   but bear in mind if your plane can stay at or above 0.3 to 1 it has enough to go to orbit/get supersonic, though acceleration will be leisurely at the times when TWR is down to 0.3

If you find yourself "needing" more than that to do these things, there is likely a part attachment problem in your design causing excess drag.

Edited April 12, 2017 by AeroGav

[Regor]

16 hours ago, AeroGav said:

The TWR bandied about in Kerbal Space program are insane.    

In the real world, you're looking at 1.2 to 1 on an F15 or F22 Raptor with a light load.     Concorde with afterburners on was approx. 0.45 to 1,  Boeing 777 with GE90 engines 0.3 to 1 (when not derating to extend engine life, they climb really steep after takeoff),  Tupolev Blackjack bomber (swing wing, mach 2, afterburners) about 0.6 to 1.

Nothing wrong with building huge TWR if you want a fighter/stunt plane/vtol,   but bear in mind if your plane can stay at or above 0.3 to 1 it has enough to go to orbit/get supersonic, though acceleration will be leisurely at the times when TWR is down to 0.3

If you find yourself "needing" more than that to do these things, there is likely a part attachment problem in your design causing excess drag.

Very helpful!