Takeoff and landing characteristics

I don't think the takeoff and landing characteristics are correct.

In MiG-15bis "Flight characteristics" book (Book 1) they say the landing speed is 170 Km/h for a weight of 3915 Kg. In "Piloting technique" book for MiG-15bis and MiG-17 they say landing speed is 172-176.

I have tried to make the slowest landing possible in simulator. Performed the landing with gun ammo removed and like 100 liters of fuel remaining. My touchdown speed was 184 (see screenshot below) with the bumper under the tail only about an inch above the runway. The aircraft was practically stalled, with little control remaining and with the tendency to bank. And despite the extreme landing and minimum weight I was only able to land at 184 Km/h. It is safe to say that landing at 170 Km/h is impossible. And I would add that in the simulator even at minimum weight for a comfortable and safe AoA the touchdown speed should be 200-210 MINIMUM.

Takeoff speed is given in Book 1 as 220-230 for a weight of 4960. Same speed is given in the other book. Performing takeoff at this weight the aircraft got airborne at a speed of 240, however the nose was raised a lot with pretty little tail clearance ramaining, and the artificial horizon in cockpit was showing about 12 deg.

First thing - in reality the takeoff and landing with this aircraft was NOT performed at Rafale-like AoA. Quite far from it. In "Piloting technique" book they actually describe what the position with the nose raised should look like - nosewheel about 20-25 cm above runway. I made some measurements on very accurate MiG-15bis scale drawings and the 25 cm they talk about would mean a pitch angle of about 7.25 deg. That would be a typical pitch angle for takeoff and landing, not 12 deg. Visually, this 25 cm means the nose wheel is raised above runway only about half of its diameter! In simulator, at takeoff (with 20 deg flaps) at a weight of 4960 if you raise the nose to just 7-8 deg the aircraft gets airborne at 300 Km/h.

All I described above strongly suggest that in takeoff and landing configuration, for a given AoA the aircraft is producing considerably less lift than it should. I don't know if it's the lift of the entire aircraft that is low or is just the effectiveness of the flaps that is too low.

I think I found what is the problem here. Or at least a part of the problem. Silly me for not figuring this sooner.

I did a ground effect test. With the MiG-15 with gear down and full flaps I performed perfectly horizontal flight at 250Km/h very low above the runway, main wheels about a diameter above runway. Then performed the same test at 50m altitude. In both cases, the necessary AoA was exactly the same. This means there is no ground effect simulated.

I performed similar tests with all Belsimtek aircraft. F-15, F-86 - same thing, no ground effect simulated. The only aircraft with ground effect simulated is the F-5. This is quite surprising, considering the F-5 is recent, but the initial release of F-15 and F-86 was more than two years ago!

In MiG-15's case ground effect would easily decrease touchdown speed with like 15Km/h, probably more.

Obvious request to Belsimtek: please implement ground effect for all aircraft. Pretty please :)

Nice findings!

+1

Thanks!

Is the ground effect still lacking in the Mig 15 ?