MachFly
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MachFly
I've been trying to figure out why Diamond put a FL180 limitation on the TwinStar (specifically DA42 NG & V1) and so far I wasn't able to find anything good. I realize there aren't too many people here who are intimately familiar with the AE300, however I'm sure there are plenty of people here who are familiar with diesel engines and turbochargers. Regarding the specifics of the engine, I should be able to explain all of that, so please ask if you do not have enough information.
Performance wise it should have no problem going above FL180. The NG can cruise at 175kts and climb at ~700fpm at that alt, the V1 should (I say "should" because I obviously never flown it) cruise at 190kts and climb at almost 1000fpm. So obviously they have the performance to go above FL180.
Specifically the limitation states "The maximum operating altitude is 18,000 ft (5,486 m) pressure altitude."
I've been able to come up with two possible theories why that limitation is there.
First one is the turbo obviously need to spin faster at a higher altitude, so perhaps above FL180 it will either overheat or go past it's RPM's red line. I never tested this, so this may be wrong.
Second theory is because Diamond kinda rushed the NG into production and the AE300 was still brand new at the time they added a whole bunch of useless limitations to try to keep it safe. The problem is that now the V1 is coming out and the limitation is still there.
The interesting thing is that Diamond posted a video on youtube (http://www.youtube.com/watch?v=RWLjD519L5A) which shows them tacking the V1 to FL200.
Perhaps that's just a testing video because the Vne is 188kts and the video shows them moving at 200kts IAS.
So any ideas why that limitation is there or what's going to happen if I go above that?
Performance wise it should have no problem going above FL180. The NG can cruise at 175kts and climb at ~700fpm at that alt, the V1 should (I say "should" because I obviously never flown it) cruise at 190kts and climb at almost 1000fpm. So obviously they have the performance to go above FL180.
Specifically the limitation states "The maximum operating altitude is 18,000 ft (5,486 m) pressure altitude."
I've been able to come up with two possible theories why that limitation is there.
First one is the turbo obviously need to spin faster at a higher altitude, so perhaps above FL180 it will either overheat or go past it's RPM's red line. I never tested this, so this may be wrong.
Second theory is because Diamond kinda rushed the NG into production and the AE300 was still brand new at the time they added a whole bunch of useless limitations to try to keep it safe. The problem is that now the V1 is coming out and the limitation is still there.
The interesting thing is that Diamond posted a video on youtube (http://www.youtube.com/watch?v=RWLjD519L5A) which shows them tacking the V1 to FL200.
Perhaps that's just a testing video because the Vne is 188kts and the video shows them moving at 200kts IAS.
So any ideas why that limitation is there or what's going to happen if I go above that?