DA50driver
Also, if you lose one engine on a twin, you loose a lot of your excess power(which makes you climb). If you lose one of three, you lose a lot less of your excess power on a percentage basis.
But since both the twin and the trijet must meet cert requirements, the worst you can ever be for FAR25 is:
takeoff first segment (gear down):
on a twin:
"positive" climb (25.121(a))
On a trijet:
0.3% climb (25.121 (a))
takeoff second segment (gear up):
on a twin:
2.4% climb (25.121 (b))
On a trijet:
2.7% climb (25.121 (b))
above 400ft:
on a twin:
1.2% climb (25.111(c)(3)(i))
On a trijet:
1.5% climb (25.111(c)(3)(ii))
So following engine failure the climb gradients are not dissimilar - which means that all other things being equal a twin will have better performance (in terms of excess thrust) when all engines are operating, which is the most common case (you hope
). So unless that 0.3% difference is make-or-break - in which case the twin won't be taking off without unloading - the twin is usually a better climber.