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arquebus

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Viewing 15 posts - 151 through 165 (of 268 total)
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  • in reply to: why doesnt europe make their own F-35? #2327282
    arquebus
    Participant

    UCAV is simply not practical and unaffordable.
    Look at the incremental trends. . 5G fighters will have 100,000lbs thrust. AWACS will have 200,000lbs thrust.
    Now this very big leap over the tiny but super expensive current UCAV.
    Space budgets are increasing so strategic survellence will be space based. but tactical survellence will be combination of UAV/AWACS/Fighters.
    More advance faster, longer range cruise missiles will equip SSN/SSGN/5G Bombers/fighter. so that you covered for around the globe strike.
    You dont need 20 years to see this trend and that being generous assumuing every one in EU is not Greece by than to built swarms of UCAVs.

    JSR- I agree with you that UCAVs are not going to replace fighters anytime soon. But not because of budgets, but because the AI in UCAVs is a long ways away from being able to safely fly and make decisions like a human pilot. But in the strike role we have already seen in the Libyan conflict that the use of Tomahawks to take out initial air defenses, that there is a need for UCAVs to do this more economically

    in reply to: Mirage 3/5 v F1 comparison #2327848
    arquebus
    Participant

    In a tailess Delta (such as MIII), the GoC and the CoL are exactly at the same location, all along stabilized flight, if not, you will have a Pich torque, and so a pitch rate….

    What you say is very wrong. The CoG has to be ahead of the CoL on a conventional (non-FBW) aircraft or else it would have dangerously unstable stall characteristics.

    BTW, the instantaneous maneuvering performance of M-III, are far better than the Mirage-F1’s one, and comparable to Mig-21MF if not better.

    To be honest, instantaneous turn rate is a very worthless measure of an aircrafts turning ability, for example an F-16 has awful instantaneous turn rate because it has a non-moving stick and it was designed for very good sustained turn rate.

    With FbW, the wing of the M2k can adopt a non “auto-stable” profile, got upfront vertice generator (aigrettes) and got slats, that allow to increase lift and pitch rate (and make the M2k even more agile than the M-III, and may be the more agile A/c of its generation), but also to significantly reduce medium AoA drag, giving the the M2K much better sustained capability (even without the benrfit of the better Th/W ratio provided by the M-53 comapred to the ATAR)

    Even without FBW the kfir has a lot better than a little vortex generator, it has a full non-moving canard, yet that does very little to improve the aircrafts handling.

    in reply to: why doesnt europe make their own F-35? #2327858
    arquebus
    Participant

    Without OOD, the progress and changes of any part of the planes design would be totally dependent on the progress and design of any other part. This may have been possible at gen 1 of fighters but for a gen 5…

    drabslab- you use the term Object Oriented Design, but what I think you really are referring to are interfaces, or more commonly referred to as an API, Application Programming Interface. You dont need object orientation to make interfaces, in fact using the object orientation of a particular language (god forbid C++) throughout a system is a particularly bad idea. The 3 most commonly used languages in critical embedded systems are C (not object oriented), C++ (formalizes C structs into objects) and Ada (which has sane type based object orientation).

    in reply to: why doesnt europe make their own F-35? #2328449
    arquebus
    Participant

    wrong again djcross

    First of all aerospace companies have their own little army of embedded systems programmers to design the control systems of an airframe. They are not going to rely on external software localized to each control surface, that would be crazy. The only thing a control surface does is change angle, you dont need isolated software to do that, its all centrally controlled. The only thing that has to be controlled in a control surface are hydraulics or some kind of servo actuated control which might or might not have been designed off the shelf by an outside contractor. In the case of FBW you need a unified system, it cannot be programmed individually.

    arquebus
    Participant

    This is why Ive always felt that air forces buying the Tucano or PC-9 are getting ripped off. These so called fighters have a top speed of about 300 kts and a vne of 350 kts. Whereas late war prop driven fighters could go 450 kts and redlines at near supersonic speeds. We have indeed gone backwards in airframe design.

    in reply to: why doesnt europe make their own F-35? #2328568
    arquebus
    Participant

    djcross,

    is it relevant that you are talking in the present tense or am i reading too much into what you post? Does all this information refer only to current systems ? If so, can you see any room for improvement?

    There is the study of “machine learning” in which computers train themselves to accomplish tasks that are far too complex for humans to program them to do. I was taking a free-to-the-public online class at Stanford on machine learning, take a look at the professors introductory video which shows a remote control helicopter being controlled by a machine learning program:
    http://www.youtube.com/watch?v=e0WKJLovaZg

    djcross- I hope youre not a professional programmer, because they way you modularize AI for an aircraft wouldnt work. A lot of systems you subscribe to AI (fuel, damage) is already controlled automatically by computers regular manned aircraft. Autopilot software already in use by manned aircraft could be used in your mythical “lowest control loop”. Higher level decision making about the mission and environment could be made by what would be the AI of the aircraft. This algorithm would take input from sensors to detect threats and weigh that on how it should evade or attack. It would be taking input from both air threats and ground threats so as to make an optimal attack profile.

    in reply to: Mirage 3/5 v F1 comparison #2329966
    arquebus
    Participant

    I suggest you look up the kill ratio of Mirage III in real wars. Somehow, it didn’t get torn apart.

    The only “real war” the Mirage III was involved in was the isreal/arab 67 and 73 wars. In both wars the best fighter it was faced with was the mig-21 which was underpowered and not an easy jet to handle. Also in 66 the Isrealis got their hands on a mig-21 from a defected pilot to test out its flying characteristics. In my opinion the Isrealis use of the Mirage III was a liability that could have been exploited by the arabs. I chalk it up to good training on the Isrealis part that they came out so well.

    Sri Lanka has Kfirs too.

    I forgot, they have 9 kfirs.

    in reply to: Mirage 3/5 v F1 comparison #2330761
    arquebus
    Participant

    Argentina is replacing the Mirage III with the F1? Can you let us have the official source for that, please?

    here you go

    in reply to: Mirage 3/5 v F1 comparison #2331018
    arquebus
    Participant

    wilhelm- I dont understand why you like the Mirage III series so much, it has awful turning capability and would get torn apart in a dogfight by just about anything with a jet engine. FBW makes all the difference, it works wonders for a tailless delta and turns it into a very agile fighter.

    Which countries are using the Mirage III/5/50/Kfir/Cheetah at present?

    Any idea of numbers?

    Almost none, they have been retired by just about every AF that used them, mostly by unloading them to Pakastan who is desperate to fly anything that will go Mach 2. I think the only AFs still using them are:
    Egypt – 50
    Argentina – 14, all are going to be replaced by F-1 next year
    Pakastan – 150
    Colombia – 24 kfirs
    Ecuador – 13 kfirs, 12 cheetahs

    thats it, no other AFs are using them

    in reply to: F-14 VS Tornado F3 #2331992
    arquebus
    Participant

    Ive always felt it was a waste to make the Tornado a swingwing being that it is a FBW jet. If they were to redesign the Tornado with a fixed wing of larger area, I think it would drastically improve its maneuvering and load carrying ability and put it back into the same level as say the eurocanards or better.

    The Tomcat was a great bird for its day, it too could be improved by making it FBW/fixed wing, but there are already plenty of good fighters for that role, so Im sure it will never happen.

    in reply to: Mirage 2000-5Mk2 vs Gripen-C/D #2369044
    arquebus
    Participant

    When the Mirage initiates a pitching moment it uses its elevons to force the tail downwards by killing lift, something most modern fighters, including the Rafale, F-22 etc does as well. The Gripen(and Eurofighter) on the other hand uses its canards for pitch wich adds lift, the elevons are used as trimming devices, adding lift

    The carnards on the Gripen do not provide neutral lift, if that were so, that would mean the CoG was put squarely over the wing making the aircraft unstable. Even FBW aircraft have to be aerodynamically stable, if you put barn door sized canards way out in front of the aircraft, sure you get hypersensitive control with minimal changes in AoA of the canard, but it would be impossible to control the overall AoA of the jet as the wings would be powerless to counter the influence of the canards.

    Also, the canards on the Gripen only needs to make very small(not severe) pitch changes during maneuvers, creating minimal drag.

    The canards on the Gripen have very small area and do have to make large pitch changes to make sharp turns, especially at slow speeds. Im not saying that canards are bad, if that were true they wouldnt demonstrate good turning ability. But they are not the magic silver bullet that gives jets hypersensitive turning rate like one might think.

    in reply to: Libyan Air Force – Resurrection #2369073
    arquebus
    Participant

    I read that at the beginning of the civil war, Libya has about 300 Mig-23s most of which were out of service, and about 100 F-1s. I dont know if these non-flyable jets were on airfields and got destroyed or in storage. But Im sure there are enough of them left to be refurbished by the Russians so that they have decent sized AF until they are ready to buy to fighters.

    arquebus
    Participant

    Im sure the guy in the article was refering to using cheaper strike aircraft like the AMX as opposed to thrashing your frontline fighters for small tasks like blowing up a truck. Same thing happened in Vietnam, a ridiculous amount of expensive hardware was used to destroy trucks and machine gun nests. It just makes sense to use a simpler aircraft for these roles.

    in reply to: Pros and Cons of different types of AWACS lay out #2369089
    arquebus
    Participant

    I dont really know anything about radar, but hasnt phased array antennas made conventional rotating arrays completely obsolete?

    in reply to: French Use of the F-8E(FN) #2369297
    arquebus
    Participant

    Possible difference if the F-8E had used French parts in them.

    how about if they had just redesigned the wing rather than go through all the modifications to make its original wing work as a carrier fighter?

Viewing 15 posts - 151 through 165 (of 268 total)