Parasite and Induced drag on Su-25/T

[capttrob]

Does it have any programmed into the design?

 

I checked out the Su-25 and 25T today. This thing is programmed more slippery than an F-15 or a MiG. lol... I was practicing crosswind landings today to check out the weather generator in this program. It takes like 5 miles dragging everything out (airbrake, flaps, gear) power at idle in level flight, just to get this thing to slow 20 km/h (numbers arent exact, but you get my point). For something so dirty looking even when its in the clean config, it sure is slippery. Whats the deal? Is there an in flight drag chute or something? lol. I thought my power was stuck so i double checked my throttle settings. Is there a button to slow this thing down?

[iVIPER21]

sounds like a substantial tail-wind component to me. remember that with regard to wind direction, the heading is where the wind is coming from - not where it is blowing towards.

[SwingKid]

remember that with regard to wind direction, the heading is where the wind is coming from - not where it is blowing towards.

 

In Flaming Cliffs? I think it uses the Russian convention, which is opposite.

 

-SK

[iVIPER21]

... that's what i get for applying real world US aviation knowledge to a russian sim, lol. Fire up FC and let us all know what you find out SK.

[capttrob]

In Flaming Cliffs? I think it uses the Russian convention, which is opposite.

 

-SK

 

That is correct (at least thats how it is in game... not sure if Russia is ICAO, but if it is, it should be reporting wind direction as from). Regardless, i used a 90 degree crosswind (roughly). My crosswind correction was about 15-30 degrees from rwy hdg. 0 headwind or tailwind component.

 

edit: To iViper, if it was a substantial tailwind, it still would not have effect on airspeed and slowing. 350 km/h IAS is the same with 100 knot tailwind or headwind. You're thinking groundspeed. Im talking airspeed.

[Dudikoff]

For something so dirty looking even when its in the clean config, it sure is slippery. Whats the deal?

 

It's quite logical - if it's not that aerodynamic to begin with and it's flying, gears and breaks are barely noticable :)

 

Actually, I think I have a recollection of reading something like that recently, about the difficulties with the slowdowns on real aircraft.

[capttrob]

I've flown alot of slippery airplanes, but nothing as slippery as the Su-25/T having such a dirty profile. Especially with full weapons load. Add the airbrakes, gear and flaps and it is still more slippery than the most slippery airplane i have ever flown in the clean config....

 

I even landed hard and collapsed the gear... the thing ran off the runway scraping its belly with a 90 degree x-wnd...lol. I touched down in the touchdown zone, full dirty config, and used the whole runway on my belly. Once i reached the grass, she cartwheeled at 50km/h and turned into a rolling fireball.... pretty funny stuff.

[Crusty]

That dont sound right...I pressume you were descending...but how steeply?

[EvilBivol-1]

This may be silly... but are you certain that you're seeing metric readout?

[capttrob]

Im pretty sure its metric..:smilewink:

 

 

Heres a track. I've only flown this airplane like 4 times, but this airplane should be slowing down alot more rapidly than it is with all that stuff hanging off it ...imo. I've never flown the thing in real life, but a Learjet doesnt even behave like this...lol. I intentionally tried to break off the gear at the end to show how quickly the plane would come to rest on the grass on its belly. Not sure if the gear broke off cause my program was on ace settings and it wouldnt change the views for me when i replayed the track, but the wingtip did look closer to the ground when i came to rest... ;).

 

Also, its a good crosswind mission if you want to challenge yourself a bit...:thumbup:

 

edit: Also note crossing the threashold there is a lack of ground effect (also indicative of lacking induced drag). I never reduced the thrust setting coming over the fence to flare. It seemed to be a bit behind the power curve already. And if thats the case, how the heck do you stop the thing if you have more airspeed at touchdown. It felt like a short field landing when i touched down.. but notice how much rwy i ate up with full brakes/airbrakes. The braking action seemed like i had a tailwind, when in reality, its a slight headwind from 209 deg (set as 029 in game....rwy heading of 280-209=71 degrees left of nose, not sure of exact rwy heading, but its still a headwind). Even so, the headwind/tailwind component at those angles are insignificant.

xwnd25t.zip

[Groove]

capttrob i think you landing speed was way to high dude. 290 km/h touchdown - try lower speed on this bird :D

[capttrob]

Anything slower and she was stalling. That airplane was already behind the power curve at 280. Notice the hard landing. My practice runs were 300-310. What airspeed do you think it should be? Show me that track with an airspeed you think it should be please.... remember.. you also have about 25 knots of crosswind.

[Kuky]

if you are fully loaded then yes, you do need a bit higher landing speed and I'd say 270-280 maybe even 290kmph sounds alright to me... the su-25 is quite heavy when fully loaded. Once you make a touchdown let the chute do its job.

[Kula66]

Anything slower and she was stalling. That airplane was already behind the power curve at 280. Notice the hard landing. My practice runs were 300-310. What airspeed do you think it should be? Show me that track with an airspeed you think it should be please.... remember.. you also have about 25 knots of crosswind.

 

240 tops ... and remember to get the chute out at 220!

[capttrob]

Heres another track i just did at a slower airspeed. Notice my glide path is about 3.5 deg (if the glide slope is standard 3.0) till i intercept. I have everything out and she aint slowing down for sh't :thumbup: . Thrust is at idle the whole time till i figure out the stall speed which was about 230-240. So i planned 250. The only reason i didnt bend the gear on touchdown is because i "goosed" the power and saved it. Normal approach speeds are calculated as 1.3 times Vso (Stall speed in landing config) on most airplanes. Stall speed is 230-240 as you see in the track. 230*1.3=299 (and i didnt even calculate this the first time... not bad..lol). This accounts for no wind and depends on weight (add more km/h for gusts and weight). As you can see, my payload was empty. I tried to release a drag chute with P practicing for my first track but nothing came out. I figured this plane didnt have one. But now that i know it does, it is helpful on the ground. Now they just need a chute when airborne...:D

250ias.zip

[capttrob]

240 tops ... and remember to get the chute out at 220!

 

Kula, i want to see you fly this approach at 240 (or lower) the whole way to touchdown without bending the gear...or getting a buffet... :thumbup:

[Kula66]

Capttrob,

Try landing on the Kuz ... no head wind and don't bend the gear - it can be done in the 25 - you just need to practice :) Oh, and remeber not to fall off the end ...

[capttrob]

I know it can be done. I just did it (at 250...with a 90 degree 25 knot x-wnd.. see track above.. not on the carrier mind you). My point is, this airplane is too slippery for the amount of Form, Parasite and induced drag it "looks" like it should have. And 240 should be "bottom" of the airspeed envelope.. not "tops". Who cares about landing a SEAD airplane on a carrier without a hook... what do you think this is.. a game or something? :smilewink: :thumbup:

 

No wind sounds like a piece of cake in this airplane... this is the first time i've practiced landings in this plane. Havent tried it with no wind. The other times i flew this plane were online... i didnt make it back to base... :D

 

edit: i'd still like to see you fly my track at 240 all the way to touchdown with a 25 knot 90 degree x-wnd. I'll buy the beer if you make it out in one piece... you except paypal? lol... i'll give you 3 hours... starting.... now... ;)

[Kula66]

a SEAD airplane on a carrier without a hook... what do you think this is.. a game or something? :smilewink: :thumbup:

 

I think calling it a SEAD plane is being very gracious! I think sending it after SAMs is just going to give some grunts a very nice firework display!

 

I prefer the 25 (not the T) ... not quite such a pig! And you can still put those great Russian rockets on in and cannon pods!

[capttrob]

Havent tried the 25. I actually prefer the A-10. But thats only because im an arrogant American.... :v:

 

 

and whats the deal with these chutes? doesnt Russia know how to make brakes? .... ;)

[Red Star]

and whats the deal with these chutes? doesnt Russia know how to make brakes? .... ;)

 

:lol:

 

 

:music_whistling:

[capttrob]

Yeah, yeah, yeah... we also have chutes on the SR-71 and Space Shuttle... whats your point? I believe the Phantom does have updated brakes and uses the chute for short field landings (among other fighters). But i think most russian fighters (modern as well) use chutes as sop?

 

Regardless.. it was a sarcastic statement if you notice the little winky at the end of the sentence.... like this one... :smilewink:

[sumoscouse]

Nice one RED STAR like your sense of Humour !! ;)

 

 

However, just in case someoine tries to point out the fact that the F4 is quite an old design then look closely please (American State of the Art) allegedly :thumbup:

 

 

 

Say No More

 

 

Cheers

 

 

SumoScouse Out :matrix:

edit CAPTTROB u got in there b4 me how dare u :matrix:

[Red Star]

Regardless.. it was a sarcastic statement if you notice the little winky at the end of the sentence.... like this one... :smilewink:

 

Chill man, I know that it was sarcastic hence why I countered with humour and not flames.

[Kula66]

Havent tried the 25. I actually prefer the A-10.

 

A2G ... agreed - the GAU-8 is just GREAT!

But the 25s has the fancier FM ... if only ED would put it in the other planes rather than waste time on the helicopter ... but then I doubt it would generate many new sales :(