SwingKid

I don't think it would be a good comparison. Besides the fact that A-10 isn't AFM in the sim, it also needs much larger air brakes because they operate at a lower speed. I wouldn't expect the Su-25 airbrakes to be very effective at A-10 speeds and I'm not testing them there, but rather at the upper end of its envelope, around 600-800 km/h. In this range I have the feeling that they aren't producing enough effect. Besides, what would be proven by comparing one simulated aircraft to another simulated aircraft? They could both be off. -SK

Hmm, it seems that the moderators closed the other discussion about this topic, so I guess we should continue here... (at least they were kind enough not to delete it...) In the previous discussion, I studied only the aircraft deceleration, without airbrakes. Without airbrakes, a 12254 kg Su-25T in a vertical dive accelerates about 7.22 m/s^2 through 700 km/h speed (~1000 m alt). From this we caluclated a cross section-referenced drag coefficient Cd of about 0.15, which seemed reasonable when compared to internet sources. Now, WITH airbrakes, a 12254 kg Su-25T in a vertical dive accelerates through 700 km/h at a reduced rate of about 5.83 m/s^2. This means that at 700 km/h, the 1.8 square-meter airbrakes are producing a deceleration force Fd = (7.22 - 5.83) * 12254 ~= 17033 N This gives a cross section-referenced drag coefficient of: Cd = 17033 / (0.5 * 1.225 * 194.4^2 * 1.8 ) = 0.4 Ok, I don't want to make any bets this time, but now it looks again like Hajduk might have a point. Comparing to some common shapes: http://www.insideracingtechnology.com/tech102drag.htm ...we can see that the AFM "claw" air brakes seem to be a little bit more slippery, than if they were shaped like spheres! I'm not sure if I made a mistake somewhere, but it seems possible to me that maybe the AFM Su-25T airbrakes are too weak. Such flat shapes generate a lot of form drag and should probably be designed to have a Cd that is about 2 or 3 times higher. I hope Yo-Yo reads this topic also.. -SK

You must be referring to one of these messages. http://forum.lockon.ru/showthread.php?p=114643#post114643 http://forum.lockon.ru/showthread.php?p=114758#post114758 http://forum.lockon.ru/showthread.php?p=131653#post131653 http://forum.lockon.ru/showthread.php?p=131673#post131673 http://forum.lockon.ru/showthread.php?p=156540#post156540 http://forum.lockon.ru/showthread.php?p=162870#post162870 http://forum.lockon.ru/showthread.php?p=171741#post171741 http://forum.lockon.ru/showthread.php?p=187031#post187031 This forum needs a FAQ. Question #1: "Why is it a waste of time for ED developers to answer me?" -SK

Ok, what would satisfy the requirements of proving that ED is in it for your pleasure, such that you would wish to eat your keyboard? I don't suppose simply, oh, I don't know - making a good enough product for you to purchase it, would be enough? :) -SK

No disrespect intended, but what is it that you're trying to say here? If it's that Il-2 popularity is out of reach for a modern air combat sim, then Falcon 4 sales disproves that. If it's that ED should focus on other things besides adding a new flyable, well, we've already had (and lost) that argument: http://forum.lockon.ru/showthread.php?t=6654 If it's that the Mission Editor programmer is gone - what's the complaint about the Mission Editor? If it's about the "great anti-Western ED conspiracy" - do you see any improvements planned for existing Russian aircraft? Ka-50 is a Ka-50. It helps MiG-29, Su-27 and Su-25 issues far less than the new AIM-120C, AH-1, Chaparral, Strykers and Georgian airbases help the Western side. I like to agree and discuss when we're being objective, but these last posts... -SK

There have been suggestions that Black Shark might include actual Georgian airbases (for the first time ever in ED's ten-years history - outside of Russian-occupied territory!) for Western aircraft to operate from. That would make me happy! :) "No promises.." -SK

I suggest to separate the "attitude" of ED testers and ED developers as two separate things. I think that some testers may post like this because we are upset by what we perceive to be "ED's attitude" too, and are just running dramatic comments up the flagpole hoping one of them will come along and correct us with a clarification. I do it sometimes too. Testers are often kept just as hungry for information about development plans as everybody else, mainly because ED is always adapting them to the new situation and don't know it for sure themselves. (Ref: Wags' signature) AFAIK every patch and add-on has always included at least some improvements for all flyable aircraft, especially when legitimate bugs are reported. The real attitude from ED has always been "no promises." The best way to avoid making promises is to avoid replying. And so the speculation about their motives always continues. So, don't take it too seriously - nothing is ever final. -SK

(SwingKid looks around at the decrepit hovel he's posting from) Uh oh.. -SK

The nerve!! - he didn't even say a WORD about my mathematics, and whether he thinks he was right or wrong about Su-25T drag!! Just rambling on about female dogs or something now. :mad: Ok thanks, that made me feel better. Let him suffer the judgement of the mods: -SK

He's not happy about the ban, or about the math? Link? -SK

Yeah, sometimes I think around here, the moderation could use a little moderation. With capttrob unable to reply, I've got no closure! Is he satisifed? Is he sorry? Who knows? It's like after 9/11 - who do you punish, when the terrorists went and killed themselves? (besides Iraq, of course) How come I have to do all the apologizing alone here?! I guess this is the way to punish me, since I would probably enjoy being banned... :) -SK

Arr!! http://forum.lockon.ru/showthread.php?t=15758 -SK

Not for missiles too. Ok, "nobody," "never.." :rolleyes: - strong words. We're not talking here about StarForce. ;) I understand your meaning, yes, but I think we should wait until capttrob's ban is finished, maybe he's the only person who needs now to be convinced. Really, with Su-25? Or Su-25T? With Su-25, I even have problems to drop the old bombs, in CCIP. :wassat: -SK

Like family ;) -SK

"slippery" = streamlined, sleek, slick A "slippery" jet (in our discussion) will be less affected by air resistance. It will glide through air almost without slowing. -SK

It might create a problem, with bomb pipper always falling below the lower limit of the gunsight in Su-25. I thought that was the original reason for putting the "helium" in the LOMAC bombs - to compensate for the reduced Su-25 cockpit downward visibility, and allow the pilot to see the bomb aiming point, that is "floating" higher as a result. Or, it's incorrect? -SK

WARNING: the above post contained a link to rude language. If you are offended by rude language, do not click the link. -SK

http://www.bozzysworld.com/images/cantsee.jpg -SK

Speaking of pictures - what's in your avatar, a rescue submersible? I've been looking at it for years and never known. :confused: -SK

I'm satisified that the AFM Su-25T, with engines off, is about 8% less "slippery" than the miniZAP artillery shell - notwithstanding the comparison against FC's own (artificially "frictionized") bombs. As long as it satisfies that condition (being less slippery than an artillery shell, instead of more), then I am personally satisfied that the "ballpark" behaviour is approximately reasonable - it's good enough for me. The AFM Su-25T's corrected Cd, as I calculate it now (with engines off), would be: Cd ~= 0.045 (wing planform-referenced) or Cd ~= 0.15 (cross-section referenced) The first number puts it in the same ballpark as the other aircraft in the list: http://www.aerospaceweb.org/question/aerodynamics/q0184.shtml The second number says that the AFM Su-25T is about twice as slippery as a "slippery road car," according to this site: http://www.insideracingtechnology.com/tech102drag.htm Draw own conclusions. For my part - even if I think the AFM Su-25T may still be a little bit too slippery, I don't think that I will be able to prove a problem mathematically anymore, and my original calculations were still wrong because of idle engine thrust. So, what more can I say? If Yo-yo says the Su-25T airframe is only 8% less slippery than an artillery shell, and a whole 50% less than a road car, what number will I invent? 30%? 50%? 80%? Maybe I would like to see it closer to half-way between the artillery shell and the road car, but that would be just an opinionated guess, no more or less convincing than the current AFM model, even to me. -SK

Winners: Yo-yo, GGTharos, Shepski, britgliderpilot, Crusty&Crusty, Weta, and the rest The idle thrust seems to be about 23% maximum bench static - 1900 kgf! And that was throwing off all my calculations, more than I expected. I WAS WRONG. Good that nobody took my bet! For Yo-yo: And now, after capttrob was so nice and concerned about my feelings, I abandon him to the wolves. :rolleyes: -SK

Ok - despite how funny that image looks, in order to prevent Yo-yo from exploding, I should admit that that's actually just drama. The problem with that image/trk is not so much with the Su-25T AFM, but rather, the LOMAC bomb flight model is a little bit "tweaked" - LOMAC bombs have helium in them, did you know? ;) Now that I look at the .trk again, with engines off, the empty Su-25T does seem to decelerate more than my original calculation showed - it now seems to fall about 8% slower than an artillery shell, rather than 28% faster that I originally estimated. I guess I should check now the 30-degree dive also, with engines off... -SK

Here's a trk that might be interesting: SwingKid's Su-25T, out-accelerating his own bombs, with engines off. http://www.ecf.utoronto.ca/~pavacic/lomac/bombrace.zip :confused: -SK

Ok, if we insist on using wing planform as a reference area, fine. Going back to this calculation, let's use 30.1 m^2 planform for S, instead of 9 m^2 cross-section: Cd = Fd / (0.5 * p * V^2 * S) = (11028.6 N) / (0.5 * 1.225 kg/m^3 * (194.4 m/s)^2 * 30.1 m^3) Cd ~= 0.016 Now, let's compare this wing-area-referenced Cd to the comparable wing values that Crusty referenced in this post: http://www.aerospaceweb.org/question/aerodynamics/q0184.shtml The Flaming Cliffs Su-25T is: more slippery than a Cessna more slippery than a Learjet more slippery than a Starfighter more slippery than an X-15 In fact, there's only one aircraft (on of the list of 17) that is less slippery than our Flaming Cliffs Su-25T. :confused: -SK

Thanks for kind words guys, but I'd really rather have the dollars. Usually at the end of fifteen pages - somebody - or the developer or the tester - agrees that he was wrong. So come on, there may be only two more pages to go - place your bets! Yo-yo or SwingKid? ;) -SK