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IRIS DA-42 Twinstar Released

Didn't Diamond have some issue with engine supply for these babies?

Which engines are fitted in this sim, or does it not really change anything?
 
It has the Thielert Centurion 1.7/2.0L engines which both have 135 hp. It's not fitted with the later Austro AE300 diesel engines which produce 170 hp. Those are fitted in the DA42 NG model which has other new part as well.
 
The main problem was with the gear(reduction) units...and that was with the 1.7L deisels only. The 2.0L engines are great. Diamond IIRC is producing their own engine now. Although I did have the left engine main coolant hose burst on me about 10 min after takeoff one time...exciting times....
 
Great aircraft! I really like the VC as well as the sounds. :applause:

However, I am not sure about the idle power of the engines. Is it correct that on ground the aircraft accelerates quickly to more than 20 knots with power levers in idle? I need to stay on the brakes the whole taxi phase in order to have the aircraft under control.

And I think, as a result of this high idle thrust, during landing the aircraft flares endlessly before it looses speed and settles down on the runway: With full flaps, power levers in idle, and 70 knots above the threshold I need more than 500 meters until the speed reaches approx. 55 knots and the aircraft touches the runway. That seems odd to me. I don't know the real DA42. But having some realworld hours on the DA20 Katana and Centurion powered Cessnas I have never experienced such a flare characteristic.

Does anyone else has these problems?

I am running FSX SP2 on Windows7 64.

Best Regards,
Sven
 
svogeler said:
Great aircraft! I really like the VC as well as the sounds. :applause:

However, I am not sure about the idle power of the engines. Is it correct that on ground the aircraft accelerates quickly to more than 20 knots with power levers in idle? I need to stay on the brakes the whole taxi phase in order to have the aircraft under control.

And I think, as a result of this high idle thrust, during landing the aircraft flares endlessly before it looses speed and settles down on the runway: With full flaps, power levers in idle, and 70 knots above the threshold I need more than 500 meters until the speed reaches approx. 55 knots and the aircraft touches the runway. That seems odd to me. I don't know the real DA42. But having some realworld hours on the DA20 Katana and Centurion powered Cessnas I have never experienced such a flare characteristic.

Does anyone else has these problems?

I am running FSX SP2 on Windows7 64.

Best Regards,
Sven
Click to expand...



In reality the idle thrust produces ~2100rpm and decreases until 25% power@~1750rpm and then increases again. There are a few reasons for this, one is the start-lock rpm of 1300, meaning if the engine is shut down below 1300rpm the props will feather rather than stay in the un-feathered position. But higher rpm = higher thrust at idle. In fact while practicing for my COMM/ME ride (in the DA42) we would increase the throttle on the "dead" engine to more closely simulate the windmill of the real dead engine.
 
svogeler said:
Does anyone else has these problems?
Click to expand...

Sounds familiar, Sven. I found it is indeed hard to slow down. There's already quite a bit of power at idle and when I move the throttle just a slight bit it increases the power by a lot.
 
Hi noobie_falcon, thanks for your explanation. However, since you have real world experience on this aircraft, can you confirm that the aircraft really needs more than 500 meters in distance to slow down from 70 kts to 55 kts during flare with full flaps? I can not believe that this is realistic, even if the twinstar has its roots in a glider. Best Regards, Sven
noobie_falcon said:
In reality the idle thrust produces ~2100rpm and decreases until 25% power@~1750rpm and then increases again. There are a few reasons for this, one is the start-lock rpm of 1300, meaning if the engine is shut down below 1300rpm the props will feather rather than stay in the un-feathered position. But higher rpm = higher thrust at idle. In fact while practicing for my COMM/ME ride (in the DA42) we would increase the throttle on the "dead" engine to more closely simulate the windmill of the real dead engine.
Click to expand...
 
Well it completely depends on temperature, field elevation and wind speed/direction. However, with that said if you look at strictly the landing distance performance data, landing over of 50ft obstacle in roughly standard conditions will yield a landing distance of ~1700 ft (+500m) at a FE of 4000ft. This does not include the ground roll.
One thing about flying from a pilot perspective is that you are not aiming to stall the airplane upon touch-down. A big factor with the twinstar is that it has a 44ft wingspan high aspect ratio wing...that's a lot of lift. Upon landing you should still have enough airspeed to almost lift off again -- you could wheely the thing if you wanted too. But the decceleration should be somewhat rapid.
One HUGE factor involved with the twinstar is that it is a propeller driven aircraft with unconventional systems that work like a jet. This is the problem (in my opinion) with it's incorporation into FS. Because the pilot DOES NOT have control over prop pitch, manifold pressure, mixture and expecially Turbo charger (this is the biggest factor I think for a twinstar modeled in FS) you have no control over the power output at various altitude/temp combinations. What I mean by this is (and perhaps it was done this way, I haven't asked) the DA42 has a turbo charger which is auto-controled. The plane has 135hp available, but the trick is to make sure that it doesn't decrease from sea level from 135. I'm not sure if that modeled into this FS plane? Sounds like the parasite drag needs to be increased a bit for a landing configuration.
 
I also find this sim very hard to slow down and it seems to have a very long takeoff roll. My horizontal stabilizer trim does not work. Anyone else have this problem? And.... how about those strobes? Interesting flash effect I have not seen on any prior simulation.
 
Hi noobie_falcon,

thanks again for your competent answer. Unfortunately I don't have the landing performance data of the DA42. I understand that the landing distance is more than 500 meters over an obstacle of 50ft at a FE of 4000ft. However with 5ft above the threshold in full landing configuration and at a FE of 10feet, e.g. Sitka, the landing distance should be much shorter. My problem is, that I do not want to stall the aircraft to the ground, but I do not want to touch the runway with a negative pitch either. However, if I maintain a very low positive pitch during flare, the plane does not settle down before the speed has reduced to approx. 55 kts. And therefore I need so much runway distance that it is impossible for me to touch down on the bars.

So I totally agree with you that the parasite drag needs to be increased for landing configuration - or the idle thrust to be reduced.

Can't that be done with a small tweak of the aircraft.cfg?

Best Regards,
Sven


noobie_falcon said:
Well it completely depends on temperature, field elevation and wind speed/direction. However, with that said if you look at strictly the landing distance performance data, landing over of 50ft obstacle in roughly standard conditions will yield a landing distance of ~1700 ft (+500m) at a FE of 4000ft. This does not include the ground roll.
One thing about flying from a pilot perspective is that you are not aiming to stall the airplane upon touch-down. A big factor with the twinstar is that it has a 44ft wingspan high aspect ratio wing...that's a lot of lift. Upon landing you should still have enough airspeed to almost lift off again -- you could wheely the thing if you wanted too. But the decceleration should be somewhat rapid.
One HUGE factor involved with the twinstar is that it is a propeller driven aircraft with unconventional systems that work like a jet. This is the problem (in my opinion) with it's incorporation into FS. Because the pilot DOES NOT have control over prop pitch, manifold pressure, mixture and expecially Turbo charger (this is the biggest factor I think for a twinstar modeled in FS) you have no control over the power output at various altitude/temp combinations. What I mean by this is (and perhaps it was done this way, I haven't asked) the DA42 has a turbo charger which is auto-controled. The plane has 135hp available, but the trick is to make sure that it doesn't decrease from sea level from 135. I'm not sure if that modeled into this FS plane? Sounds like the parasite drag needs to be increased a bit for a landing configuration.
Click to expand...
 
Just tried an engine out landing. The speed still reduced fairly slow during flare, but it seems to be much more realistic to me - at least I succeeded to hit the runway within the touchdown zone. So that will be my interim solution, killing the engines just before flare! :icon_lol: (just kidding)

Best Regards,
Sven
 
the plane is great but I have question to other owners

is it only me that trim is too much nose down I mean it looks like it is not Trimed Neutral?


BR
Tom
 
I'm not quite sure what needs to be edited as far as FS files, however, what you are describing is probably not enough parasite drag. There certainly is sufficient power for idle forward movement in the real airplane. Not to the extent described, but definitely forward movement. In the real airplane the following should hold true for the power settings:

Takeoff: 100% and about 10-12 degrees pitch up to hold 85 kias

down wind pattern (gear up): 55-60% to hold 106 kias

down wind pattern (gear down) 69%

abeam threshold - flps aprch - about 47% and hold 90 kias

base - same

final - 44% slow 85 kias

short final - ~40% or what needed to hold 76

aiming point should be the second stripe from threshold

crossing threshold - power to idle

flare - not a typical flare bring nose level only -- allow airspeed decrease

allow airplane to "fly onto" the touch down 1000' markers (smooth hands during this phase slight back pressure)


I've NEVER missed a short filed landing EVER using this technique (or slight variations of it) in DA42.
**power settings may be slightly off as I haven't flown it in about 1.5 years but IIRC pretty close.... lol... ;)



@tom

Trim position indicator is ONLY an indicator of the physical state that the trim tab is in. It shouldn't be used to determine what should be giving you level flight or not. kind of like the attitude indicator, in that level flight isn't always when your miniature airplane is on the horizon line :)


Just so everyone knows ---- I DO NOT HAVE THIS AIRCRAFT ----- All info is based on my experience flying the real one...so don't expect it to match exactly! ;) ----
 
@noobie_falcon and Sideshow: Many thanks for the landing instructions and the link to the AFM. Both very useful!!! :ernae:

Best Regards,
Sven
 
Ok, so in layman's terms please. . .is this a worthy purchase? I looked at a few of the reviews on the Simmarket site and it was panned pretty bad from several who claimed it wasn't even good freeware quality. For me, even a purchase in the $25 range is a major purchase anymore, so I don't want to buy this one and end up being an unhappy beta tester.:salute:
 
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