Could it be that the aircraft behaves differently on FSX SP2 compared to FSX Acceleration? At least with the F16 this has lead to some issues regarding the engine thrust. As I have already written in the sticky thread, I cannot believe that the Twinstar looses speed so slowly during flare with full flaps...
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IRIS Twin Star_"Deal or a Dud"?
- Thread starter falcon409
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Could it be that the aircraft behaves differently on FSX SP2 compared to FSX Acceleration? At least with the F16 this has lead to some issues regarding the engine thrust. As I have already written in the sticky thread, I cannot believe that the Twinstar looses speed so slowly during flare with full flaps...
N400QW
Charter Member
I think you are confusing us [Eaglesoft] with Iris. We've not done an F16 so can't address what Iris does.
My statement was about our DA42, not Iris's....
Ron Hamilton
Eaglesoft Development Group
As already stated, all in all I like the IRIS DA42 very much. That is the reason why I am so anxious to find out why I have so much problems slowing it down, almost not being able to land it on small airfields.
In order to demonstrate what I mean with "slowly loosing speed during flare with full flaps", I made some screenshots - pictures say more than words:
View attachment 6415
Short before the runway threshold in landing configuration (full flaps, speed 73 kts).
View attachment 6416
Just passed the runway numbers. Still flaring with engines in idle and low pitch in order to keep the aircraft just above the runway. Speed has reduced by only 2 kts to 70 kts.
View attachment 6417
... and still flaring... more than one third of the runway is already used... speed has reduced to 60 kts.
View attachment 6418
Finally the aircraft has settled down with a speed of 58 kts. More than half of the runway has been used. Now, I have to stay with both feet on the brakes in order to get the aircraft to a stop before the runway end. It's easier to land a B727 on this runway!
If the cause for this endless flaring is not the FDE, WHAT am I doing wrong?!?
Best Regards,
Sven
In order to demonstrate what I mean with "slowly loosing speed during flare with full flaps", I made some screenshots - pictures say more than words:
View attachment 6415
Short before the runway threshold in landing configuration (full flaps, speed 73 kts).
View attachment 6416
Just passed the runway numbers. Still flaring with engines in idle and low pitch in order to keep the aircraft just above the runway. Speed has reduced by only 2 kts to 70 kts.
View attachment 6417
... and still flaring... more than one third of the runway is already used... speed has reduced to 60 kts.
View attachment 6418
Finally the aircraft has settled down with a speed of 58 kts. More than half of the runway has been used. Now, I have to stay with both feet on the brakes in order to get the aircraft to a stop before the runway end. It's easier to land a B727 on this runway!
If the cause for this endless flaring is not the FDE, WHAT am I doing wrong?!?
Best Regards,
Sven
Hello Ron,
sorry for the confusion, I meant the IRIS DA42. I didn't know, that you are also going to offer a DA42. I am really keen to try that out in order to have a comparison regarding the flight characteristics of both addons...
Best Regards,
Sven
sorry for the confusion, I meant the IRIS DA42. I didn't know, that you are also going to offer a DA42. I am really keen to try that out in order to have a comparison regarding the flight characteristics of both addons...
Best Regards,
Sven
N400QW
Charter Member
falcon409
SOH-CM-2025
Yep, I know no one reads what I post, but I continue to be baffled by this rage over the FDE. I don't have any problems with the flight dynamics of this airplane and I have realism settings pretty much maxed. The inability to stop this baby was simply due to higher than allowable landing speeds. I just kept at it until I hit the stall speed and adjusted back from there. I still think the brakes are too soft, but when you touch down now around 60kts, over the numbers, you can land on just about any rwy.
I think it's a beautiful airplane, beautifully modeled and great fun to fly.:salute:
BUT I do not land with "higher than allowable landing speeds". If you have a look at my final approach speed you see that I am already below the 76 kts recommended in the original AFM (and the IRIS documentation). Ok, you can of course fly a final approach speed of 60 kts, but that is not realistic. You would never fly the approach in this aircraft with a stall margin of less than 5 kts - unless it's absolutely necessary for a very short landing. And what speed would you choose for a landing in gusty conditions?
I still assume that the modelled parasite drag with full flaps is way too low.
I still assume that the modelled parasite drag with full flaps is way too low.
N400QW
Charter Member
Spoken like a real world pilot. I well remember my instructor teaching the same thing....
The only permissible time for such low speed ops were "slow flight at altitude" and of course "short/soft field" training.
I've not flown the DA42, either real world or the Iris version. Nor have I read any of the documentation for the aircraft, so all that follows is purely speculative. However, I picked up on one line in either this thread or the other which made me think a bit - something about the wings being very 'glider-like'. If that is the case, might I make a suggestion?
In my time flying gliders (real world), the only time we would use flaps for landing would be for short landings. Also, they would be lowered on entry into the circuit and the entire circuit flown with them down, speeds adjusted accordingly. This is because a glider wing is designed to be efficient, and the flaps are primarily lift-creating devices, rather than being designed to add drag. If you lowered flap on finals, it was highly likely that you'd completely overshoot the field.
With the DA42, would it be worth trying a flapless approach at the speed mentioned, or a full-flap approach at 66kts (i.e. approximately 10kts above stall speed)? For a small aircraft like this to be approaching at 17kts above stall speed (assuming perfect conditions) just seems a bit excessive, especially with a very clean wing.
In my time flying gliders (real world), the only time we would use flaps for landing would be for short landings. Also, they would be lowered on entry into the circuit and the entire circuit flown with them down, speeds adjusted accordingly. This is because a glider wing is designed to be efficient, and the flaps are primarily lift-creating devices, rather than being designed to add drag. If you lowered flap on finals, it was highly likely that you'd completely overshoot the field.
With the DA42, would it be worth trying a flapless approach at the speed mentioned, or a full-flap approach at 66kts (i.e. approximately 10kts above stall speed)? For a small aircraft like this to be approaching at 17kts above stall speed (assuming perfect conditions) just seems a bit excessive, especially with a very clean wing.
I would like to comment on how planes seem to fly differently on different computers and installations. Pam, you brought up that it handled differently on your two computers, between the two. I found this to be a reality.
When I came out with the Tailwind addon, it handled great for testing, handled like a jewel on my computer, but a handful of people found it totally uncontrollable. I couldnt believe it but one guy even filmed it on YouTube, so it was happening. I retuned the file 2 times, ending up making it a very numb aircraft for those that had computers that were over-reacting the controls.
Doing AFM's are one hairy, difficult, stressful, ultra sophisticated thing to do in FS development. I compare it to 'aircraft engineering' on a light to moderate scale. Being able to get all the figures to work and have the aircraft handle 'exactly' as it should is a grandiose endeavor and great achievement. You do not know how difficult it is. The way MS has these variables worked and the way they are entered, you change one thing, and you just changed 5 others as well. Change the HP and suddenly your fuel range is out, your top speed is too high, she accellerates too fast, the torque turns you on tail draggers, your MP doesnt match your cruise speed, your left nostril nose hairs eject, and exactly 7 starboard eyebrow hairs will either eject or turn some wild, metallic silver, also innitiating a slight eyebrow tick or twitch.
Not to mention.............. Air density, air temperature, loadout of a plane, fuel onboard, winds and prop type will all effect a 'real' plane, so 10 actual aircraft in different parts of the world will all act/behave so totally different from each other...
The way I see it, with this being a flight simulator (not real, a thing projected on a screen) that you have to account for the fact that this is not real and you have to give things some area for error as it just cant be perfect... It can be dang close, but thats as far as you will get.... Even with A2A, you get so real as to even have Carb icing, (very awesome feature) but then people might complain about that too.... Just fly it! Quit stairing at the screen with a magnifying glass, lol... Have some fun. :d
When I came out with the Tailwind addon, it handled great for testing, handled like a jewel on my computer, but a handful of people found it totally uncontrollable. I couldnt believe it but one guy even filmed it on YouTube, so it was happening. I retuned the file 2 times, ending up making it a very numb aircraft for those that had computers that were over-reacting the controls.
Doing AFM's are one hairy, difficult, stressful, ultra sophisticated thing to do in FS development. I compare it to 'aircraft engineering' on a light to moderate scale. Being able to get all the figures to work and have the aircraft handle 'exactly' as it should is a grandiose endeavor and great achievement. You do not know how difficult it is. The way MS has these variables worked and the way they are entered, you change one thing, and you just changed 5 others as well. Change the HP and suddenly your fuel range is out, your top speed is too high, she accellerates too fast, the torque turns you on tail draggers, your MP doesnt match your cruise speed, your left nostril nose hairs eject, and exactly 7 starboard eyebrow hairs will either eject or turn some wild, metallic silver, also innitiating a slight eyebrow tick or twitch.
Not to mention.............. Air density, air temperature, loadout of a plane, fuel onboard, winds and prop type will all effect a 'real' plane, so 10 actual aircraft in different parts of the world will all act/behave so totally different from each other...
The way I see it, with this being a flight simulator (not real, a thing projected on a screen) that you have to account for the fact that this is not real and you have to give things some area for error as it just cant be perfect... It can be dang close, but thats as far as you will get.... Even with A2A, you get so real as to even have Carb icing, (very awesome feature) but then people might complain about that too.... Just fly it! Quit stairing at the screen with a magnifying glass, lol... Have some fun. :d
falcon409
SOH-CM-2025
Typical. . .you don't read the entire paragraph and "listen" to what I'm talking about, you simply key on one phrase and go off on it.
If you stop and read what I was talking about, you'll see that I was talking about me landing at higher than allowable landing speeds. My gosh, get the dang chip off your shoulders people and "READ" and "COMPREHEND" before you go off half cocked. Everybody has an agenda. . .get off the soap boxes will ya? I started this thread to get feedback on whether or not the airplane was worth buying. . .it's turned into a bash this and bash that free for all.
I don't care what ya'll think about the engineering aspects of the upper and lower dihedral of the sacroiliac as it relates to the kinetic energy of the forward lift potential. I just wanted to know if it was worth buying. . .I bought it, I love it, I have no idea what everyone is up in arms about with the FDE, personally I don't think any of you have a clue what you're talking about save maybe warchild and Lionheart and one other. . .you just like to hear yourself talk. Get over it will ya!!
Perfectly valid and polite comments have been made. Nobody has an agenda.
He also perfectly addresses your original post. You posted that;
To which he responds that that is an incorrect approach procedure (which it is). N400Q says that his comment was 'spoken like a true pilot' (which it is). His comments are valid.
Delta558 said:
Flaps are both lift devices and drag devices. In a Cessna 150 for example, 10 and 20 degree flap provides more lift than drag, 30 and 40 degree flaps provide more drag than lift. Try going around on full flap and you'll see what that feels like!
Also, that margin for error is not uncommon at all. Back to the Cessna 150, approach speed is 65 knots, whilst stall in dirty config is 47 knots.
warchild
Charter Member
Gentlemen!.. Gentlemen.. Please..
I can hear a lot of frustration in here on this, and with the directions we've taken, it's completely understandable. I myself, without intending too have added to that frustration.. I am sorry for that. Please accept my apologies..
Now!..
Sven.. I completely understand your frustration, not only with the aircraft but the responces you have recieved. It was that same frustration that caused me to start doing flight models in the first place. Believe me, i used to hate ( and fear ) trignometry with a passion you simply would not believe.. Now, its practically all i do.. Anyway!..
i did a quick run around the web last night, and found a whole lotta real world pilots complaining about various aspects of the DA-42, and especially its slow top speed. i did not however find any complaints about it acting like a glider, floating or landing two knots above stall speed..
SO, heres what i'll do..
Sven..
i cannot ethically or legally change any of those files, but, i can find a solution to your problem and tell you what that solution is. As its my weekend, i can probably do this in the next few hours. For your part, your going to need a copy of the files ( aircraft.cfg and DA-40 XLS.air ). However, please be aware that ANY changes we make, will change other aspects of the planes behaviour.I'll do my best to avoid that however.
Pam
I can hear a lot of frustration in here on this, and with the directions we've taken, it's completely understandable. I myself, without intending too have added to that frustration.. I am sorry for that. Please accept my apologies..
Now!..
Sven.. I completely understand your frustration, not only with the aircraft but the responces you have recieved. It was that same frustration that caused me to start doing flight models in the first place. Believe me, i used to hate ( and fear ) trignometry with a passion you simply would not believe.. Now, its practically all i do.. Anyway!..
i did a quick run around the web last night, and found a whole lotta real world pilots complaining about various aspects of the DA-42, and especially its slow top speed. i did not however find any complaints about it acting like a glider, floating or landing two knots above stall speed..
SO, heres what i'll do..
Sven..
i cannot ethically or legally change any of those files, but, i can find a solution to your problem and tell you what that solution is. As its my weekend, i can probably do this in the next few hours. For your part, your going to need a copy of the files ( aircraft.cfg and DA-40 XLS.air ). However, please be aware that ANY changes we make, will change other aspects of the planes behaviour.I'll do my best to avoid that however.
Pam
Thanks, Skittles!
@falcon409: I had no intention to critisize or offend you. So please let's continue this thread polite and with respect to each other. English is not my native language, thus, it is difficult for me to express my thoughts - and I surely could not compete with your hard words.
If you had read my posts carefully, you should have no reason to accuse me of bashing the product or of just wanting to hear myself:
And if you still hold me for a nitpicker, than you are right. In my job as a design engineer for real world aircraft it's almost a requirement. :d
Peace?! :ernae:
Best Regards,
Sven
@falcon409: I had no intention to critisize or offend you. So please let's continue this thread polite and with respect to each other. English is not my native language, thus, it is difficult for me to express my thoughts - and I surely could not compete with your hard words.
If you had read my posts carefully, you should have no reason to accuse me of bashing the product or of just wanting to hear myself:
I enjoy this addon, but I would enjoy it even more, if I can land it in a realistic way, according to the manuals and without any cheating. And thus, I am looking for help in order to either find a mistake in my procedures or to tweak the FDE accordingly. If I just wanted to bash the product, I surely would not have made the effort to post screenshots of my landing attempts.
And if you still hold me for a nitpicker, than you are right. In my job as a design engineer for real world aircraft it's almost a requirement. :d
Peace?! :ernae:
Best Regards,
Sven
warchild
Charter Member
Ok.. for those having difficulties. Here is what you can do..
go to your your iris DA-42 Twin Star folder in your airplanes directory, and open the aircraft.cfg file with notepad.
theres a couple changes you can make in there..
First. Scroll down to the [airplane_geometry] section of the file and change the "oswald_efficiency_factor" to 0.76 from 0.90
Next, and just below that entry, Change the wing_area from 144 to 177 ( trust me on this please..)
Third, change the next entry down ( Wing_span) to 44.200
finally scroll down to the [Flight_tuning] section and change the "cruise_lift_scalar" entry to 1.0 from 1.2.
Thats it.. you should be able to enjoy the plane at this point..
The high efficiency factor is the main thing that was causing the lift. people dont always realize just how important that little number is, but even in real world aircraft where its called the same thing but expressed as 'e" it determines the amount of lift capable of being generated by a wing. a hypothetically perfect wing, has an "e" factor of 1.0. This is a wing what is 100% efficient in lifting. frankly, youd never be able to land with it.. ng would have the cross section of a perfect elipse and create no drag, no matter if it was upseide down or right side up. its a perfect wing.. Thankfully, for us, there is no such thing, so most wings are less that perfctly efficient. A Beech barons wing comes in with an "e" factor of about 0.83. A B-17 somewhat higher ( and bomber crews always had problems landing when they first started learning the plane ). An F-104 has an "e" factor of maybe 0.2. its about as eficient as a lazy kid.. you really gotta push it to get any work out of it.. The diamond has a modified half elipse wing. i forget the NACA number, but its a good wing, but it doesnt generate near perfect lift. Based on its span, and its narrowness, i gave that a much lower "e" factor because in relation to the work it has to do, its not going to be as efficient as say a broader semi eliptical wing. the Span and area entries i changed to match the dimensions given for the actual wing. yes, it surprised me too to find out the span is wider and theres more area. Especially since your having problems with floating..
my test flight was uneventful. rotate at 75 ( no flaps) lift off at a little over 80, once around the airport at 96, apply flaps in a dive and drive configuration at the end of the runway and set down at 68 knots.. it wasnt pretty, but, it didnt float.. So give those nu,bers a shot and i do hope they help..
Pam
go to your your iris DA-42 Twin Star folder in your airplanes directory, and open the aircraft.cfg file with notepad.
theres a couple changes you can make in there..
First. Scroll down to the [airplane_geometry] section of the file and change the "oswald_efficiency_factor" to 0.76 from 0.90
Next, and just below that entry, Change the wing_area from 144 to 177 ( trust me on this please..)
Third, change the next entry down ( Wing_span) to 44.200
finally scroll down to the [Flight_tuning] section and change the "cruise_lift_scalar" entry to 1.0 from 1.2.
Thats it.. you should be able to enjoy the plane at this point..
The high efficiency factor is the main thing that was causing the lift. people dont always realize just how important that little number is, but even in real world aircraft where its called the same thing but expressed as 'e" it determines the amount of lift capable of being generated by a wing. a hypothetically perfect wing, has an "e" factor of 1.0. This is a wing what is 100% efficient in lifting. frankly, youd never be able to land with it.. ng would have the cross section of a perfect elipse and create no drag, no matter if it was upseide down or right side up. its a perfect wing.. Thankfully, for us, there is no such thing, so most wings are less that perfctly efficient. A Beech barons wing comes in with an "e" factor of about 0.83. A B-17 somewhat higher ( and bomber crews always had problems landing when they first started learning the plane ). An F-104 has an "e" factor of maybe 0.2. its about as eficient as a lazy kid.. you really gotta push it to get any work out of it.. The diamond has a modified half elipse wing. i forget the NACA number, but its a good wing, but it doesnt generate near perfect lift. Based on its span, and its narrowness, i gave that a much lower "e" factor because in relation to the work it has to do, its not going to be as efficient as say a broader semi eliptical wing. the Span and area entries i changed to match the dimensions given for the actual wing. yes, it surprised me too to find out the span is wider and theres more area. Especially since your having problems with floating..
my test flight was uneventful. rotate at 75 ( no flaps) lift off at a little over 80, once around the airport at 96, apply flaps in a dive and drive configuration at the end of the runway and set down at 68 knots.. it wasnt pretty, but, it didnt float.. So give those nu,bers a shot and i do hope they help..
Pam
Okay, I've just downloaded the manual for the DA42 (which Diamond make available on their website: http://www.diamond-air.at/da42_afm_bas+M52087573ab0.html ) and I am a bit confused. P.135 gives reference speeds, including a final approach speed of 76 / 78 kias dependant upon weight. The emergency speeds in the case of an engine failure (i.e. single engine landing) on P.106 are identical. Yet there is a note about this on P.107 which states:
"Higher approach speeds result in a significantly longer landing distance during flare." This is directly after the same approach speeds have been given.
Am I misreading? Or is there possibly a discrepancy here?
Am I misreading? Or is there possibly a discrepancy here?
strykerpsg
SOH-CM-2023
Falcon,
I have to agree with Skittles and maintain that the thread hasn't totally gone off track and since it was titled "Deal or a Dud"? it garnered my attention too, because I have purchased most of Iris' earlier items and enjoyed them, just not too crazy about their latest releases so wanted to see the feedback others have as well about their purchase. Perhaps in the future titling your thread more along the lines of "accurate FDE" versus Deal or Dud, may bring more comments about the FDE instead of some feelings about Iris or other producers.
As for the content contained within the thread, I am pleased to see many other opinions, including those from Eaglesoft on their characteristics. As a matter of fact, I was elated to see Eaglesoft producing one (DA42) as well, since someone told me most producers will not make duplicate aircraft, so as not to compete with other poducers, a claim I found a bit contrary to a free market society.
Thanks all for the feedback, looking forward to more.
Matt
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