Unrealistic high speed at low altitude in a fighter possible

  • Hi,


    I can fly at Mach 2.0 at sea Level with the F-15, which is not possible in reality due to the air drag in real life at that altitude. Do you plan to implement a more realistic flight model in the future for this great sim ? Btw I love the new Florida DLC. It is really great to fly low and slow with a prop plane there.


    thanks in advance

    Dirk

  • I think the point is that it is unrealistic that the sim allows you to do that intead of obeying the actual performance limits of the aircraft. At low altitude the F-15 maximum speed is Mach 1.2 - 900 mph, according to Wikipedia.


    Just saying don’t fly faster than that to make the flight realistic misses the point. The plane shouldn't fly faster than that in the first place.

    Thrustmaster HOTAS Warthog, MFG Crosswind pedals, 2 dof Motion, HTC Vive Pro

  • I think it is (theoretically) possible to fly faster than your Wikipedia numbers. But if your plane would be braking because of the forces, the manufacturing will set the never exceed speed accordingly and Wikipedia will write down this as the maximum possible speed.


    In AF2 there is no never exceed limit simulated, so you can fly at any speeds your engines will let you... In reality you would end up without wings or other serve damage...

  • As far as I know the F15 is theoretically able to fly faster than mach 3! But the canopy will melt away above mach 2.5 and the engines will melt also when using the V-Power for too long.


    So in my opinion the F15 speeds should not really be drag limited but heat limited (engines and airframe).

  • Jan,


    you are Right. In reality it is not possible to fly that fast at sea level but in this sim it is, if you take a look at the mach number, which is displayed in the HUD.

    Because of that, I would like to know , if the flight model will become more realistic with a future update.


    Ubbi: the Density of the air at low Level is much higher than at 30.000 feet. That's the reason why you can reach high mach numbers at that high altitude.

    Beside from that you are right that it is also much colder up at high altitude, so the friction heat is less


    regards

    Dirk

  • As far as I know the F15 is theoretically able to fly faster than mach 3! But the canopy will melt away above mach 2.5 and the engines will melt also when using the V-Power for too long.


    So in my opinion the F15 speeds should not really be drag limited but heat limited (engines and airframe).

    I prefer facts over opinions especially when there are so many discussions of the F-15's "clean" maximum speed which would tend to indicate it is drag/power limited.

    Thrustmaster HOTAS Warthog, MFG Crosswind pedals, 2 dof Motion, HTC Vive Pro

  • "But the canopy will melt away above mach 2.5"

    There is an hardware-canopy addon for the sim that can simulate melting? =O


    But seriously: There is a lot you can do in the sim that cannot be done in real live.

    I guess this issue will be recorded, prioritized and solved when high enough in the priority list.

    Just normal software development.


    Cheer up. :)

    Wish for Aerofly FS 2:

    - Flightpath recording on hard drive and replay in sim from different view points

    - Smoke for aerobatic planes

    - Multiplayer or at least watching other people flying sitting on ground or inside tower

  • For goodness sake - please don’t remove the ability to have a blast, screaming up the valley from Insbruck at a 100 feet, doing Mach 2 in a F15, at the altar of someone’s desire to match a singular performance number to a book-value!

    Flying A330 as a day-job and enjoy VR-flying with PIMAX 5k+. NextLevelRacing v.3 Motion platform, Watercooled and overclocked i9-9900k, 32Gb 3600RAM, Samsung 970EVO Pro 2Tb m.2, nVidia RTX-2080Ti FE, Thrustmaster HOTAS, VKB pedals, Cockpitforyou motorised throttle quadrant, Precision Flight Controls Jetliner column

  • Thruth is probably none of us here really knows what the F15 is capable of. Just cause one source in the internet says so doesnt meant it is correct. It will take a lot more research and right now it doesnt make sense to try to match the max speed only. If you had data for a level deceleration from say 400 to 300 kts then it would be ok to try and tweek the drag. But transonic and supersonic drag behaves counter intuitive, first it rises really high than it actually gets lower when you fly faster and so on.

    But this isnt simulated correctly yet, might be in the future

  • Here is a quote from a former F-4 Phantom Pilot (John Chesire):


    What I do know is that at altitude, aircraft are limited by their maximum Mach number , far before they ever reach their maximum indicated airspeed. However, when flying fast at lower altitudes, the converse it true. Indicated airspeed rather than Mach number is the limiting factor. This is because of the thinner air at altitude compared to dense air at sea level.
    For an example, the F-4 that I flew was limited to Mach 2.23 at altitude. (1,472 mph, 2,370 km/h). However when flying low at sea level, the maximum speed we could fly in the denser air was only 1.34 Mach (863 mph, 1,389 km/h) because of our limit of a maximum of 750 knots indicated airspeed.
    Egressing after a combat strike, we flew “on the deck” as low as we could go and as fast as we could go in our F-4s. Sometimes we even exceeded our F-4's 750 knot speed limit if sustaining heavy enemy opposition... and needed to get the heck out of there, fast! In fact we occasionally came back with the paint on the leading edges of our wings bubbled, singed, and burned by the high-speed and low-altitude air friction heat.



    Ozav8r and Zed: The best solution of that problem would be an option in the menu, where you can choose an arcade or realistic flight model


    regards

    Dirk

  • Thruth is probably none of us here really knows what the F15 is capable of. Just cause one source in the internet says so doesnt meant it is correct. It will take a lot more research and right now it doesnt make sense to try to match the max speed only. If you had data for a level deceleration from say 400 to 300 kts then it would be ok to try and tweek the drag. But transonic and supersonic drag behaves counter intuitive, first it rises really high than it actually gets lower when you fly faster and so on.

    But this isnt simulated correctly yet, might be in the future


    Um, the F-15 is a fairly old plane and first flew in 1972. Older models already sit on pedestals and in boneyards, or are already disposed of as scrap. If you search Amazon's book section, there are 273 search results for F-15 Eagle - many of them technical. The aircraft is pretty well known and while some information may still be classified (probably only certain systems and not the plane itself), it’s pretty trivial to get good performance numbers for it. Just saying one reference does not a simulator make is a cop out. I'm not the one trying to market a simulator. I only mentioned supporting information for Dirk's original comment.


    You can certainly do what you want. I only commented in this thread because I thought just saying "don't go so fast" is a pretty lazy way to develop a "simulator". That approach will get FS2 a reputation as a game and not a simulator pretty quick. Not my sim, though, or my call on how to run your business.


    Dirk - an arcade mode might be useful and not that different from the difficulty levels in other sims. Again, only my opinion, but easy to fly is still different from performance way outside the envelope. Otherwise we can sit back and wonder when we get our supersonic 737. ;)

    Thrustmaster HOTAS Warthog, MFG Crosswind pedals, 2 dof Motion, HTC Vive Pro

  • There is a lot more to how fast a plane can go than just thrust available and thrust required. A real world pilot obeys limitations to fly any aeroplane. Exceed what is allowed and bad things will happen.

    High speed aircraft have a stability speed limit, they can go out of control before they run out of thrust, consider a minor high speed lateral or vertical displacement, at twice the speed the alteration of angle of attack on the vertical or horizontal stabilisers is reduced to one half and the aerodynamic correction is reduced. To go faster increased stabiliser area is required.

    It makes some sense to simulate planes going out of control or breaking up if flown too fast. Has there been an attempt to model Mach tuck in the diving P-38?

  • These conversations (for me) approach medieval arguments about how many angels can dance on the head of a pin.


    It's also like the old doctor joke where the patient says "Doctor it hurts when I do this." and the doctor says " Then stop doing that!" :D


    Personally this is waaaaaaaaayyyyy down at the bottom of my list of things to worry about, after landing lights that actually illuminate the runway, so that night flying actually becomes a sensible option, etc.

    Devons rig

    Intel Core i7 8700K @ 5.0GHz / 32.0GB G.SKILL TridentZ Series Dual-Channel Ram / ZOTAC GAMING GeForce® RTX 2080 Ti Triple Fan / Sound Blaster Z / Oculus Rift VR Headset / Klipsch® Promedia 2.1 Computer Speakers / ASUS ROG SWIFT PG279Q ‑ 27" IPS LED Monitor ‑ QHD / 2x Samsung SSD 850 EVO 500GB / Windows 10 Pro 64-bit /Gigabyte Z370 AORUS Gaming 5 Motherboard