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Unrealistic landing and emergency air system doesnt work.


motoadve

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Wow, you are even questioning a RW pilot who flies both planes IRL, that's something new! Did you actually read what motoadve wrote???

 

Bad start really...that is sad.

I think you don't get my point or I used the wrong words. I'm not questioning anybody there. Except maybe your way of reply...

Actually I'm extremely interrested in comments from experienced people like motoadv and i don't need to be sermoned by others.

 

Now I guess motoadv like anyone here would like this brake wrong behavior to be fixed. Right ?

If so we need to gather strong arguments. We can't ask devs to modify this or that on a single comment (even highly reliable). They need numbers, they need proofs/documents. That is just it.

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OK, so before we start fitting guns to our Yaks..... :huh:

 

Moto, you might have already checked this but have you got a trk file we can see, maybe we can work out the stopping distance from that and compare?

 

I've seen the stopping distance quoted as 200m for a Yak so can see your point. I have the brakes on a rotary control and for me the brakes are a bit nothing... nothing... face splatted on the instruments. :D

 

Also I think there's a file where you can edit the friction coef. of the tyres, I'll need to do some searching..... :book:

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I've seen the stopping distance quoted as 200m for a Yak so can see your point.

Where did you read the 200m? That's still a lot less than the flight manual 300m figure.

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Ninja'd by Woodbuster. :thumbup:

 

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-)


Edited by Magnatilla

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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.


Edited by bbrz

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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? :helpsmilie:

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:

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?


Edited by Magnatilla

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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 ;)


Edited by bbrz

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S.L. Sea level.
so yeah, I'm slow... :doh:

 

 

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.


Edited by Magnatilla

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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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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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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.

 

02lp2cD.jpg

 

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).

 

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.


Edited by Ramsay

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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.


Edited by bbrz

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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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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...

Motoradve used 90m, that's a 30% increase...

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Well, if he does it without flaps then it reinforces my impressions.

Where did he write that he achieved the 90m without flaps?

I don't understand why you are testing without flaps at all since there aren't any performance data for this configuration available.

Don't know what to say if you think that the deceleration with and without flaps is identical….

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Rewording:

 

According to my tests with our DCS Yak52.

- Of course flaps' drag do impact flight speed but I didn't notice significant direct effect during the landing run deceleration.

- Adjusting "Max brake moment" from this: 0.33 * 8000.0 to that: 0.02 * 8000.0 makes our DCS Yak52 braking capabilities closer to what the OP reported from his CJ6.

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I try short landings on taxiways and stop in 300ft, its like touch down and arrested by a hook in a carrier.

Impossible and unrealistic.

 

Tried closing the main tank, and running out of air by lowering and retracting flaps and gear, at the end ran out of air, the air pressure gauge still indicates I have air, so does not work.

Put lever in neutral, open the emergency tank, lower the gear, nothing, does not work.

 

 

I fly a real CJ6 Nanchang, same systems, and same landing roll as per the manual as the Yak 52. It cannot stop in 300ft ever.

 

This needs to be fixed, no ground effect whatsoever either.

Pretty disappointing.

 

I fly a YAK52 IRL and can 100% confirm you will never land a YAK52 in 300ft. Pumping the brakes is definitely the way we were taught.

Also, if you fail to retract the flaps on a touch and go, you really do notice the extra drag.

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if you fail to retract the flaps on a touch and go, you really do notice the extra drag.

The question is, does the Yak still climb at 160km/h with the gear and flaps down, although only very shallow of course.

Pulling the throttle to idle in dirty config results in an almost Wilga like ROD. 10m/s.

In level flight with the gear down, retracing the flaps will increases the speed by more than 100km/h (no change in power setting).

Is that correct?

 

A bit OT, but when reducing the speed from 200km/h to 110km/h (Vst pwr on), with throttle and prop full forward, there's basically no change in rudder application required to keep the ball centered. Is that correct?

 

Thanx in advance :)


Edited by bbrz

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Pumping the brakes is definitely the way we were taught.

 

Hello,

Stupid question: What would happens if, during landing, you'd fully press the brake without pumping ? Would it behave like a car brake does when it got air in lines ? Or would it damage something ?

 

Also, if you fail to retract the flaps on a touch and go, you really do notice the extra drag.

 

I think this is not the case with our DCS' Yak. So this is something else to report I guess.

 

 

Thank you for the help.

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"Hello,

Stupid question: What would happens if, during landing, you'd fully press the brake without pumping ? Would it behave like a car brake does when it got air in lines ? Or would it damage something ?"

 

 

Both tyres will burst very quickly

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"

Both tyres will burst very quickly

 

Sorry there's something I don't understand.

If brakes are not effective and you keep the brake lever pressed I can understand an overheating and damaging with brake lining and then a more or less complete loss of braking but why then tyres would burst ?

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If brakes are not effective and you keep the brake lever pressed I can understand an overheating and damaging with brake lining and then a more or less complete loss of braking but why then tyres would burst ?

 

They likely burst due to tyre skid.

 

SKID BURST

 

POSSIBLE CAUSES

Skid bursts result from brake malfunctions or locking of the wheel, most often during landing. Without tire rotation, the rubber and carcass plies are quickly worn through leading to the bursting of the tire.

 

img_eandr_46.jpg

 

Note: I've found UK incident reports re: a Piper skid burst, but Yak-52 reports seem mainly related to the landing gear.

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