Unrealistic landing and emergency air system doesnt work. - Page 4 - ED Forums
 


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Old 07-05-2019, 06:59 PM   #31
Magnatilla
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Ninja'd by Woodbuster.

Quote:
Will you use the map view to measure the braking distance ?
That was the plan, not sure how do-able it is but, hey, we could make a spot landing competition out of this.. {B-)
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Old 07-05-2019, 07:13 PM   #32
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Quote:
Originally Posted by Magnatilla View Post
That was the plan, not sure how do-able it is but,
To measure takeoff/landing performance I'm using S.L. airports where I have measured the distance between the transverse joints. That way it's easy to measure the exact distance.
Flight manual 300m at Vapp 160km/h and the websites 200m at Vapp 130km/h looks plausible.
Unfortunately both don't mention the actual touchdown speed and if you mention only the landing roll without the landing distance, the landing roll value is of little value.
Using 160km/h I need 200m without an excessive flare and a touchdown between 130-140km/h.

Last edited by bbrz; 07-05-2019 at 07:16 PM.
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Old 07-05-2019, 07:25 PM   #33
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It's been a long hot Friday, forgive me if I'm being slow...

bbrz, what's S.L. airports? I am guessing you're saying measure the landing roll, taking it as a relative distance compared to the runway length on map view?
Quote:
To measure takeoff/landing performance I'm using S.L. airports
We await something from Moto but I'd assume he's landing as slow as possible from he OP:
Quote:
I try short landings on taxiways and stop in 300ft
I'll put this out there too, does anyone else find the Yak to be very floaty with no engine landings, almost as if ground effect comes into play?
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Old 07-05-2019, 07:30 PM   #34
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S.L. Sea level. Anything higher and the takeoff/landing roll will be longer.

I'm measuring the distance in ME first and after the landing I'm watching the replay from the external view to measure (or more precisely count) the divisions to measure the distance from the actual touchdown to the full stop.

The guy in the RW video was also touching down rather slow, approx 115km/h but that's still more that 60kts.
Without disk brakes, antiskid and prop reverse 100m would be a real challenge for every plane

Last edited by bbrz; 07-05-2019 at 07:38 PM.
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Old 07-05-2019, 07:33 PM   #35
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Quote:
S.L. Sea level.
so yeah, I'm slow...


Quote:
100m would be a real challenge for every plane
Exactly, and it's why I think we need to get a measurement from DCS. Am interested in the results you get and will try it myself when I can.
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Old 07-05-2019, 07:44 PM   #36
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I don't have access to my DCS PC for a few days to do tests, but with the much lower touchdown speed (115 vs 130-140) way less than 200m is definitely possible...in DCS...
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Old 07-05-2019, 08:33 PM   #37
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Okay that's a start.
We could potentially prove that in DCS the yak-52 can perform a max perf landing run on less than 200 m of runway.
Now the trick is ; could we demonstrate that is not possible in real life ? Please do not shoot... I read what you wrote but from a developer's POV that is not enough. On my side I'm searching on the internet but it's hard to get something on this specific topic (and to get numbers, developers love numbers !). Without numbers we could try a report from a bunch of YAK-52 pilots if you know some (we could try CJ6 pilots' report but I'm afraid it could dismissed by devs) . Are we on the same freq at now ? Or should I expect to be looked down on again?
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Old 07-06-2019, 12:21 AM   #38
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Quote:
Originally Posted by Magnatilla View Post
Exactly, and it's why I think we need to get a measurement from DCS. Am interested in the results you get and will try it myself when I can.
The best tool to use would be Tacview, the free 'Starter' version should be sufficient for your purpose.



I had a 220m takeoff roll vs the 170m minimum but used Vr=130/Vto=140 rather than Vto=120

DCS landing roll was approx 260m vs the 300m minimum but I didn't pulse the brake as is recommended IRL.

These were just quick and dirty tests, so I'm sure with repetition, the distances might be reduced (I don't fly the Yak-52 much).

Quote:
Originally Posted by THE DEFINITIVE PILOTS OPERATING HANDBOOK 1.4 2003
5.1.2 Take off Run
Minimum run required from standstill to lift off (120 Km/h) and at the maximum all up weight is 170m.

5.1.3 Landing Run
Using full flap and at maximum weight and using maximum braking the minimum landing roll from touchdown to full stop is 300m.

Both take off and landing distances will be affected by weight, runway conditions, and wind components. Full use should be made of the CAA General Aviation Safety Sense leaflet on Airplane Performance.
Attached Files
File Type: miz Yak-52 Acceleration and landing roll test, Batumi.miz (10.1 KB, 11 views)

Last edited by Ramsay; 07-06-2019 at 12:33 AM.
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Old 07-06-2019, 04:19 AM   #39
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Quote:
Originally Posted by Ramsay View Post
DCS landing roll was approx 260m vs the 300m minimum but I didn't pulse the brake as is recommended IRL.
Your touchdown speed is the same as mine, ut your landing roll was noticeable longer. Did you apply full braking immediately upon touchdown?
I'm not sure if the brakes are the actual problem.
The DCS Yak flaps IMO have way too much drag, which has been confirmed by AcroGimp and ground effect is completely missing. Both bugs will shorten the landing roll.

edit: Just found the correct touchdown speed in the manual. 115-120km/h. So the 115km/h in the 'short field' video isn't any slower than the normal landing speed.

Last edited by bbrz; 07-06-2019 at 09:19 AM.
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Old 07-07-2019, 01:24 PM   #40
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Not sure about the flap drag influence in that landing run distance story. At my shortest, I did a120 meters run (or so) without any flaps...
This said, I've done some experiment. I simply changed the max brake moment from this: 0.33 * 8000.0 to that: 0.02 * 8000.0
My shortest stop distance is now 260m (or so).
This could be increased a bit more to match the official 300m but then the aircraft might become a pain during taxiing.
Motoadve, is the result something acceptable from your pov or should it be more(or less) drastic ?
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