vparez

Hi Zeus, Just in case you missed what I asked earlier: the DRP switch in the cockpit currently turns in a continuous manner, will you be changing this to a sequence of discrete positions? It would be easier to manipulate with the mouse if it is discrete positions (like the radio knobs or INS mode knob). Also, if you don't mind, what is this panel that Azrayen was mentioning which isn't modeled? Keep up the good work! This module is by far my most favorite!

I would like to second the parallel dispensing of chaff and flare for the panic mode. Preferably, and if possible with 0.25s interval for chaff (6x) and double that 0.5s for flares (3x). That way the program finishes dispensing both types at the same time. By the way, the BVR programs make a lot of sense from the point of view of the epoch in which the Mirage was introduced; only SARH missiles were expected. The program button is probably not designed to be fiddled with during combat, so I don't think that the sequence of programs really matter. You are not going to gradually move the button as your range to the bandit decreases, you have plenty of workload already with the radar, RWR and sticking your eyes out of the cockpit to spot visually. From my point of view this button is like your setup for bombs; you will select the correct fusing, ripple and interval long before your drop the stores, based on your attack profile and the expected target. BTW I forgot: @zeus67 do you plan to change the mechanic of the in-cockpit button for program selection? Currently it is a continuous potentiometer-like movement; it would be a lot easier for mouse manipulation if it becomes a sequence of discrete positions.

I have to reluctantly agree with the operator here. Reluctantly, because I dont like to talk bad about people trying to work hard and do a job I couldnt do myself. What concerns me about VEAO is that they have the worst rated module in the game and, at the same time, the biggest list of projects... In addition, they want to do the Typhoon... a very new plane which is mostly still a secret. That says to me that they have a serious issue with understanding the scope of the job they embarked on, and some bad decision making.

Ok buddy, I am going to leave it at this. I am not playing with words nor trying to troll you or anything like that. However, be careful when you say a thing like "at 14deg AOA you have turbulent flow". In fluid mechanics this doesn't mean much. As always, thanks for a nice discussion. I didn't know that jets were landing with higher RPM than needed, so I am happy to have learned this.

Flow separation can occur in laminar as well as turbulent flow, that's not the issue. The issue is that nobody was mentioning flow separation. Gears come down way (and slats go in) before touchdown and, correct me if I am wrong, you don't fly the whole final at 14deg AOA. So I was first thinking about the approach, before I would get into a discussion about a more extreme attitude near touchdown. If I reflect on the discussion, I should have realized that even at smaller AOA there would be some separated flow towards the TE and the slats would indeed make a difference. It is important to be clear when you discuss like this through messages; see how Azrayen thought I said I had jet fighter experience because I was not clear enough :D

Still, the camber of the sealed slats have an effect on the separation. The Mirage wing near the root has a very large cord/thickness ratio, so with slats extended, i guess it can actually be approximated to a flat plate with a small camber near the LE. In the NASA video that Zaelu posted you can see that this camber is better with respect to separation than a flat plate without it. So although there is no ventilation, the camber and increased cord length do play a big part.

Ok, I understand now what is the problem. Sure, if there is flow separation over the wing, SLATS will reduce total drag. So, I agree with what you and Azrayen said, I just needed this additional piece of info (that we were talking about separated flow). And yes, at typical AOA of a final approach there is bound to be separation, so slats out would reduce drag. So, ok, I don't have a problem anymore with this explanation of why SLATS are in with L/G out; thanks for a nice and enlightening discussion! Here is a picture I was trying to find yesterday, it is very telling: Of course here we can only compare FLAPS vs FLAPS+SLATS but the principle is the same and it is regarding CL vs CD. For a CL=2.4 drag is much lower with SLATS (blue line) than without (red dash line). This is only true as the AOA increases enough to cause separation. We can clearly see that when AOA approaches 0, the SLAT config has more drag than the FLAPS or CLEAN configuration.

Ok, look, it is really simple: I just do not agree that deployed slats reduce drag (i.e. that retracting them increases drag). I could be wrong, but I don't think so. If I am wrong, I have no problem of admitting that, but I can't simply accept this claim without explanation. So, if you can explain how slats decrease drag I would be very grateful. :)

1st I dont have a story about the stability issue. It is not me who said that. I am saying that it could be a risk in the case of malfunction so thanks for agreeing with me. 2nd, you mean with l/g retracted? What am I repeating?

@Azrayen, thanks a lot mate for the reply! (no problems with french) ;) Ok, I totally understand why you would manually extend slats in case of power loss. Power loss means less speed, means higher AOA to keep the same lift. As you push to higher AOA you are approaching critical stall, so you extend slats manually to delay a critical AOA to a higher value. I would suppose that they advise manual extension so that the slats are fully extended ("on peut avoir, train sorti, les becs plein sortis") so that a pilot doesn't have any surprise if the automatic system malfunctions or if the computer suddenly (for whatever reason) decides to change the configuration at a critical moment. You need a stable configuration on landing. (this is just my thinking I dont have any info) I agree that slats do not create lift, and I misspoke there. What I was trying to say is that at the AOA where slats are working, the lift is greater than at any other smaller AOA. As lift increases so does the induced drag. The induced drag originates from the recirculation around the wing tips from the lower to the upper wing side. If you have lift then the pressure on the top is smaller than the pressure on the bottom, hence this recirculation. But I am sure that slats cannot decrease drag compared to a clean config. :)

:thumbup: @Azrayen

@Jojo and Azrayen, could you please share the text from the official documentation where it elaborates on the clean configuration having more drag than configuration with slats deployed? I am guessing that there is another context in which this applies and that we are discussing ad infinitum because we dont have this context. I stand by what I said before: if you deploy slats the profile drag might slightly increase but it is usually not very much, but if the slats increase lift, then your induced drag will also increase. So, for constant AOA, slats = + drag Now, about the context... if your lift is increased more than total drag then your finesse will increase which is usually a good thing for a glide-like flight. So, what your technical documentation says must be looked at in the correct context. Any possibility to see this doc? I would be really interested. @Azrayen, Yes, I see what I wrote and how you might have taken it the wrong way. No, no I certainly don't have any hands-on experience with jet fighters! I just land my little ULM with throttle on idle, and yes I knwo its not the same as Tanguy and Laverdure! :D @bbrz, I stand corrected, there are sealed slats. Thanks! Do you know how do they function? Is their job to increase wing surface?

Then they are not slats, and since they don't rotate they are not LEFs. They are a totally unique piece of french engineering like a 2CV! :D There is a gap between slats and wing LE. The separation of the two profiles creates circulation around each one, and the interaction between these yield the benefits to the drag and lift. Do you agree that the gap provides the primary physical mechanism of how slats do their thing? Otherwise, please explain to me through which physical mechanism do BECKS in the Mirage change lift/drag/AOA. Check around 9:15 here: https://www.youtube.com/watch?v=q_eMQvDoDWk No, I never flew a delta wing fighter. Is this the only way one could be able to define what is a critical or near critical regime? I always thought such knowledge came BEFORE the first flight, from engineering calculations or wind tunnel testing. And I did a lot of wind tunnel testing. ;) I would define a near-critical regime for AOA for which you don't have a linear relationship between CL and AOA. But that's just a criterion of the top of my head, I would have to look into it more to see what does literature say. Most likely there is no fixed definition, or there are multiple definitions like for a boundary layer thickness. Thanks for the data, but I was thinking what is the critical AOA if you don't use slats, nd compare it to the max AOA used in landing. I am quite curious to try it out. Also, since you know a lot of stuff about the Mirage, could you confirm what another member posted earlier about the AOA at which slats are deployed? If his numbers are correct (from 4deg AOA onwards) it could be a good clue in this discussion. One thing I don't understand from your posts is what you are saying about slats and drag. Drag cannot be HIGHER in the clean configuration than in the deployed slats configuration. The deployment of slats slightly increases the profile drag, but the increase in lift also increases induced drag. So, I don't see how slats can be used to REDUCE drag. But maybe we missunderstand each other. In any case, nice discussion! ;)

@Azrayen, what does TAS and RS stand for exactly in french?

Well I don't know if you can make such a general statement. I think it heavily depends on the plane type and the aerodynamic design philosophy. In my pilot training the first thing I was told was that the take-off is the most critical phase with respect to engine failure, not the landing. This makes sense, since at landing you are slowing down continuously while on take off you struggle to accelerate. Now, all I am saying is that I do not believe that you would purposefully need engine power to land, while at the same time being near a critical flight regime. IMHO the design of the plane would first ensure that your flight regime is with a nice margin, and only then would a designer worry about the engine response in extraordinary situations. You don't sacrifice the safety during a normal landing so that you can have better options if you need to brake off. How many times in a plane's life do you land normally and how many times do you go around in an emergency? But this is all beside the point, the point is what Azrayen said: without slats your AOA is higher. This is what I don't agree with since in the textbook definition slats do not change your AOA for most of your flight envelope, but only near the critical regime; and you don't land in the critical regime. What are the critical AOA for stall for the "clean" Mirage and what is the normal AOA at landing? I will test it tonight after work if nobody does it before.

I don't think this is the reason; have a look at my previous post. Also, if you engine runs higher RPM to maintain flight, there is more chance of a disaster if your engine dies. So, that's not a great design decision.

Here is a nice picture of the effects of slats and flaps: http://aviation.stackexchange.com/questions/1734/what-is-the-difference-between-flaps-and-slats You see that slats do not have an effect on lift until near critical angles of attack; probably this is why they are not used in landing. There is no need for them and possibly could aggravate the situation in case of a one-sided failure. The flaps in this picture are not entirely accurate, as they should reduce the critical AOA (curve is shifted upwards but also to the left), not keep it the same as in the clean configuration. This is due to the additional drag caused by the flaps (quite a lot of it). Hinged LEF have the same aerodynamic purpose as their trailing edge flap counterparts: change the camber of the wing. They are in the F-16 and F-18 I believe. Since they rotate downwards, they certainly increase profile drag, but one needs to look at this with respect to the general characteristics of the wing design. There is probably a good pay-off when they are used, in spite of added drag, but I would expect the effect to be similar to flaps. In addition to this, they can also be used to optimize the airfoil profile for high-speed flight. Slats (as in the M2000c) are designed to separate from the wing leading edge, providing a slot through which the incoming air is accelerated, which then energizes the top wing boundary layer (which delays flow separation as previously mentioned). Since slats are extended mostly to the front of the airfoil (and very slightly upwards) they do not create much additional profile drag, and by their action of controlling the boundary layer, they keep the drag of the whole wing remain lower than if they werent used (not really in level flight, the effect is only at higher AOA where you have flow separation on the top).

Thanks for the reply! Hmmmm, yeah good point about deltaH vs a waypoint; when I think about it, there is most likely a waypoint relatively near to the intended target which can be used to provide the H.

As far as I understand we have 3 options of CCIP bomb delivery: 1. Using ballistic computer which doesn't know what is the true ground height at the impact point, nor what is the above ground altitude of the plane; 2. Using 1 + RS; knowing the true vertical distance to the ground below the plane by radar altimeter then assuming the ground is the same level at the impact point; 3. using 1 + TAS; radar to directly measure the slant range to the impact point. If the above is correct, and since we don't designate the target in CCIP, how is then the slant range measured in TAS mode? How does the radar know where to look? Does it look automatically at the initial pipper solution by the ballistic computer and then projects a true impact point on the HUD? And what happens if the initial CCIP solution is below the radar elevation gimbal limits? There is no visual cue for this? And, if the plane is above a mountain at the moment of release (all around it is flat ground) and the target is on flat ground, does it mean that using the RS mode will induce a bigger error than if only the ballistic computer was used?

Well, that's the catch. All examples of US engagements are foreign wars with a huge one-sided advantage. In such an environment, it pays much more to expend stores in abundance than to risk a shooting down of your own plane by what is described in the media as a third-world airforce. If that happened it would be a big embarrassment for the USAF and the government, costing much more than a couple of tens of thousands of dollars of a missile, which is probably already near the end of its shelf life and would need to go back to the manufacturer for refurbishment (which again costs bucks). Hence, in every US engagement you have a gross over-expenditure of ordinance of all kinds (they even gave it a catchy name "shock and awe"). This is of course officially justified by preserving the lives of US servicemen and women, but nobody (out of the people who make decisions) really cares about that. Its about maintaining a good domestic and international PR and giving the military industry stuff to do at the same time... yay!

@acdelta57, no, this problem was a while ago and I did all the INS alignment and the physical backup compass was showing a bad heading as well. @Mirknir, i flew a mission today and everything seems normal, I can't replicate my "strange" HUD. Sorry for raising alarm for nothing. Cheers!

Hi, sorry I didn't understand... where do you click on the HSI? There is the mode switch, and there is the other +- switch. But if I turn the +- switch nothing is changing... So how do I manually slave the hud? By the way the backup compass is also showing the same wrong heading. @Mirknir, ok mate, I'll try to put a screen tomorrow!

:rolleyes:

Hi all, I have some strange problems with the m2kc on open conflict. A while ago when a winter map was on, my compass was always shifted by about 90 degrees. A couple of days when I tried again I got a very strange HUD symbology. Anyone else experiencing this?

Sometimes you get killed instantly, but I think it depends a lot on the missile type. An SA-3 hit will almost always take you out cold. That being said the DM is quite obviously unfinished but I am sure that RAZBAM will put in some effort before the final release. So far they are doing a smashing job on the Mirage!