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Su-25T crosswind competition


peterj

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I recently discovered how fun the 25t is in strong winds. A what wind speed can you make a clean landing?

I'll start with 14 m/s there I'm definitely clean :)

 

Rules:

The default 8m/s crosswind Su-25t mission, increase windspeed

Increments of 3 m/s (8 11 14 17 20 ..)

 

Crosswind landing basics:

 

Lower the wing facing the wind, use opposite rudder to stay alligned to the runway.

 

or

 

Fly the aircraft with an angle into the wind, you'll move diagonally not facing straight at the runway, so called crabbing. Straighten out the aircraft just before touchdown. This looks cool but I've had less success with this technique so far.

 

http://stoenworks.com/Tutorials/Crosswind%20Landings.html

 

 

su25t_crosswind.jpg

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Day time? easy. :D

 

Night time in fog with 400m cloudbase. tricky but again easy and fun plus needing a rear right tyre. :p :D

 

http://forum.lockon.ru/showthread.php?t=11987

 

sorry for responding to the attempted hijack of your thread PeterJ. I'll give the crosswind landing a go.

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Crosswind meaning perpendicular to the runway?
In the 8 m/s mission that i mentioned (it's in the su-25t missions folder) the wind is crossing the runway at something like 20 degrees from the incoming aircrafts point of view.

 

I'll try the Kuz. Thought if it get's to hard it might be more luck than skill ;)

The crosswind is a gradual challenge and the goal is to make it nice, not just get down without breaking anything.

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I almost made 50 m/s at 90 degrees, after touchdown the gear was trashed and the plane was blown a few hundred meters away from the runway before I could restart the engines and counter the wind ;)

i7-2600k@4GHz, 8GB, R9 280X 3GB, SSD, HOTAS WH, Pro Flight Combat Pedals, TIR5

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I know crabbing doesn't work in lomac due to a lack of airbrakes, but I guess if you time the flap retraction well, you can crab without blowing tires, or ending up in a ditch.

 

I'll give the mission a try later.

 

Also, we should revive the air racing competition, this time with a su-25(t) :)

Creedence Clearwater Revival:worthy:

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I know crabbing doesn't work in lomac due to a lack of airbrakes, but I guess if you time the flap retraction well, you can crab without blowing tires, or ending up in a ditch.

 

I'll give the mission a try later.

 

Also, we should revive the air racing competition, this time with a su-25(t) :)

Eh... there are airbrakes on the planes... what do you mean?

i7-2600k@4GHz, 8GB, R9 280X 3GB, SSD, HOTAS WH, Pro Flight Combat Pedals, TIR5

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you need to kill lift fast when crabbing, otherwise you won't have enough grip on the runway (because the wings carry the most weight), spoilers come in handy here, as they extend quickly, and kill lift. The tiny airbrakes of the su-25 are next to useless when it somes to killing lift on the main wings, and the flaps don't retract fast enough. (by the time you have sufficient grip you're already plowing the dirt).

 

Managed a 50m/s crosswind "landing" (no broken tires ot other broken things), but I had to land perpindecular to the runway, which reminds me of that joke: "Hmm, those runways are damn short, but sooooo wide"

Creedence Clearwater Revival:worthy:

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If you can do that you must be doing something right :) Post a track.

 

Here's a 20 m/s just for the sake of it, http://tinyurl.com/7n23z (su25t_20sk.wmv)

No flaps, touchdown at 350 km/h IAS

I keep blowing the tires at 26 m/s ..

 

You can't do this with the 25t http://djay.myftp.org/div/flightsim/Pousos.wmv , boeing test flights with some sick set angles

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50m/sec

 

50*60*60 = 180,000 m/h or 180km/h, so you could just about land sitting still relative to the ground...

 

Not quite, you still have some forward speed, but, as I said, the width of the runway is enough. Hence the "oh my, what a short runway, but it's soooo wide" joke.

Creedence Clearwater Revival:worthy:

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And taking off with a cross-wind of 50m/s? I try to imagine it, but I fail :P

Whisper of old OFP & C6 forums, now Kalbuth.

Specs : i7 6700K / MSI 1070 / 32G RAM / SSD / Rift S / Virpil MongooseT50 / Virpil T50 CM2 Throttle / MFG Crosswind.

All but Viggen, Yak52 & F16

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FF, question. Why would one remove lift during a crab? For better tire adhesion to the runway?

 

Are you refering to techniques heavier aircraft, such as a 747, employ on dangerous approaches such as into Kai Tok? However, for an aircraft that size with that much square area per foot of lift, spoilers are a must.

 

For an Su-25T, why would you reduce lift at low speeds during a crab? Perhaps to "plant" the aircraft on the runway? I assume this is done immediately upon touchdown.

 

By far, the easiest method to accomplishing the landing is with crab on short final then forward-slip prior to touchdown. Even in real world flying, that is what I have always done although the tires squealed a bit until the plane settled onto the gear...perhaps dumping lift is a good idea to settle down quicker.

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FF, question. Why would one remove lift during a crab? For better tire adhesion to the runway?

 

Are you refering to techniques heavier aircraft, such as a 747, employ on dangerous approaches such as into Kai Tok? However, for an aircraft that size with that much square area per foot of lift, spoilers are a must.

 

For an Su-25T, why would you reduce lift at low speeds during a crab? Perhaps to "plant" the aircraft on the runway? I assume this is done immediately upon touchdown.

 

By far, the easiest method to accomplishing the landing is with crab on short final then forward-slip prior to touchdown. Even in real world flying, that is what I have always done although the tires squealed a bit until the plane settled onto the gear...perhaps dumping lift is a good idea to settle down quicker.

Does forward slip mean you set it at an angle? because I havn't been able to do that with the 25t in lock on, it will blow the tires. The tire weakness seems a bit overmodelled thought.

 

--

 

Weta43, nothing broken, to begin with :)

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  • ED Team
In the 8 m/s mission that i mentioned (it's in the su-25t missions folder) the wind is crossing the runway at something like 20 degrees from the incoming aircrafts point of view.

 

I'll try the Kuz. Thought if it get's to hard it might be more luck than skill ;)

The crosswind is a gradual challenge and the goal is to make it nice, not just get down without breaking anything.

 

 

To be accurate, guys, I think will be better to make a homebrew mission: Razdolnoye airfield (Runway heading exactly 0 deg) and wind 90 or 270 degrees. As far as I know the record is 15 m/s without any damage. I think it will be extremely hard or even impossable to counteract banking from the wind on landing run.

Safe your wingtips. :)

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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quote=peterj

 

Does forward slip mean you set it at an angle?

 

A forward slip is excuted when the upwind wing (that side of the aircraft wind is originating) rolled or banked into the wind and rudder is used to counteract the natural tendency for centripetal force to turn the aircraft.

 

because I havn't been able to do that with the 25t in lock on, it will blow the tires. The tire weakness seems a bit overmodelled thought.

 

A Forward slip can be done in LO-MAC. It it more difficult to control vertical descent and settling too hard on one wheel will result in a burst tire.

 

I conducted some experiments on undercarraige durability. I determined it takes a sharp vertical load on the main gear to bend them, a hard lateral side load to pop a main tire, and an excursion of the nosewheel in either direction at sufficient speed to pop all tires.

 

It does not appear sensitive to me and can take quite a punishment. Even off-field landings (not recommended) at high weight can put some punishment on the undercarraige itself without damaging anything.

--

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What about - land, turn around & take off again. I suspect the front tyres are a bit fragile, but if you can get it down, turn & take off, you've got a working machine (& the blown fron tyre will make the takeoff more tricky anyway).

Cheers.

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This is a little difficult :O

Is the rudder effectiveness accurate? A SIDE slip is basically not possible. Even at full rudder deflection, you can not keep your aircraft's longitudinal axis parallel to the runway. For me, crabbing has been unsuccessful without popping tires or having a large drift when lining up (causing more stress to the tires). Even the 152 (flying leaf :D) can be landed much easier in similar crosswinds lol.

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