F-101C Voodoo vs MiG-15 Fagot-A

[Toryu 156]

@ steve

Thanks for the offer of the file, but my lack of thorough understanding concerned the mechanics of the ejector-nozzles on most jets (as you already said: most designs are not con-div, but use secondary air to form the divergent part). Many text-books only treat nozzle-design to the point where they'd say "you need a con-div design", but they fail to mention how most ejector-nozzles actually work. Most jets do not feature a con-div nozzle that approaches the Laval-nozzle design, but rely on a much simpler approach in only providing a throat-area (primary nozzle) and a defined exhaust area (for the lack of a better word), which is the secondary nozzle.

Some designs use(d) a primary and secondary nozzle, while others only used a primary nozzle, which was convergent-only. Aircraft equipped with these (eg. Tornado) are still able to achieve supersonic Mach numbers of 2 or more.

Most text-books I've seen pretty much oversimplify ejector-nozzle design.

 

@ streak

You'll have to admit, that SF does not simulate transonic issues pretty well. There's no change in pitch-authority or control-forces (talking about the MiG-17), so a lot of what actually made the difference IRL is missing.

Combined with the limitations of properly simulating human behaviour, this generally spoils the real-life advantage (or effectivity) of some aircraft. A well-flown F-101 was probaly better-off in a real fight against MiG-17s than in-game.

 

Interestingly, the MiG-19 is somewhat of a mixed bag. Some sources rate it superior to the MG-21 for all practical matters, some rate it as a sure kill.

Edited August 12, 2014 by Toryu

[MigBuster 2,875]

Best you can do is restrict the flight surfaces in the FM at certain speeds e.g.

 

MaxControlSpeed=230.0

LockoutSpeed=257.0

 

The MiG-17F has these restrictions by default - although not sure they apply to AI considering the speeds they still appear roll at. These controls don't account for any changes due to altitude.

 

Gail Peck mentioned the flight column got very stiff between 400-450kts on the MiG-17F with powered flight surfaces - it also snap rolled due to adverse yaw. TK probably assumed most players don't have rudders so adverse yaw is not apparent in any of the stock FMs.

 

 

Comparing MiG-21F-13 to MiG-19S - on paper the MiG-21 has more fuel /less thrust, is lighter, lower wingloaded, has a bigger radar and a similar static TW.

 

The North Viets seem to suggest they preferred either the MiG-21 or MiG-17 over the MiG-19S (J-6) - the Soviets were sure quick to get rid of it.

 

 

 

 

 

 

[Toryu 156]

IIRC, the israelis rated it above the MiG-17 and favourable over the MiG-21 in some circumstances.

The radar in the Fishbed C is nothing to write home about anyway.

[MigBuster 2,875]

Israel obtained and flew a few MiG-17s and a MiG-21F-13 in the 60s - not aware they had any 19s - so they perhaps assumed the MiG-19 was a combination of the 2 regarding performance.

 

In Ospreys Mirage and Nesher Aces, Amos Amir states the MiG-19 as being an inferior aircraft and a bad fighter - though maybe just his opinion.

[+streakeagle 866]

The MiG-19 is great on paper, and therefore is great in a sim based on paper. In reality, it had some "issues" that made it unpopular with pilots. Its performance relative to other MiGs is comparable to RAF Lightnings compared to its contemporaries: excellent power-to-weight and low drag with all great performance that implies (climb, acceleration, etc.), but apparently its biggest flaws were in reliability/maintenance and possibly stability/control issues.

 

I think TK added the control limits with WOV. With original SFP1 up to the long time standard SP2a, the MiGs faced no limits at higher speeds. The transonic region has always been a problem for TK. The original flight models ini files used 0.4 Mach intervals: 0.4, 0.8, 1.2... etc. That's a pretty big jump in data points that makes covering the sudden changes between 0.8 and 1.2 impossible. As a result, most aircraft perform far too well over this speed range and I can remember the F-105D being unable to go supersonic initially because the drag was too high. I think in SF2, TK doubled the resolution to Mach 0.2 intervals, which offers some improvement. But even then, there is still a lot of change going on between Mach 0.8 and 1.0 that determines why an F-86 was better than a MiG-15bis at high speeds. It would take an interval of 0.05 Mach to show some of the intricate differences in drag, but that is overkill for the rest of the speed range outside of Mach 0.8-1.2. The solution would be to have data ini files with variable resolution rather than a fixed interval. That would keep the total number of data points reasonable, but still allow great fidelity at critical speeds. 

Edited August 13, 2014 by streakeagle

[Do335 382]

Can I ask a dumb question...

 

So we have all the data points defined in the FM. For example CD, CL of the wing etc. But apparently they're all coefficients, and what calculates them into a force would all requires an amount of surface area. So where is the size of the surface area defined? min/max extendpositions or... does the game engine automatically calculates it from the 3d model file? Seems to me the former is somewhat inaccurate and latter is a bit unlikely...

[Fubar512 1,350]

Can I ask a dumb question...

 

So we have all the data points defined in the FM. For example CD, CL of the wing etc. But apparently they're all coefficients, and what calculates them into a force would all requires an amount of surface area. So where is the size of the surface area defined? min/max extendpositions or... does the game engine automatically calculates it from the 3d model file? Seems to me the former is somewhat inaccurate and latter is a bit unlikely...

 

The coefficients and surface areas are determined from real world data.  Generally, the more data points in a given table that one makes available to the game engine, the closer that flight model comes to behaving accurately.  That being said, as was mentioned earlier, there are parameters that aren't modeled due to the limitations of the game engine, and certain liberties must be taken in order to simulate them.  One example is wing warp, another is the effects of compressibility on control surfaces. 

[stephenmcparlin 8]

@Toryu

I once had a long conversation with an Albanian ex-fighter pilot (bizarrely enough, working in a restaurant in Farnborough). He had been current at some point on all of the Chinese-manufactured MiGs that the Albanians had operated (MiG-15UTI advanced trainer, the -17F, -19S and -21F). He rated the -19S as having the best handling characteristics of them all, which surprised me, as the sweep/aspect ratio combination is well beyond the conventional pitch-up boundary, although the big tailplane will help.

I have a presentation copy of the History of TsAGI (in Russian), of which I can read a little, but it shows the development of flow control devices on swept wings in their low speed wind tunnels through the 1950s (mostly tufted models in the T-101 tunnel at Zhukovsky). It is noticeable that the MiG-19 has the largest fences know to man or beast at near mid-semispan. While these look agricultural by modern standards, it is clear from looking at these, and later models of the 57-60 degree delta wings that eventually went onto Su-9/11 and MiG-21, that the Russians in the early 1950s hadn't yet cottoned on to the potential for non-linear lift from vortex flows, which the British, French and US were beginning to exploit by the mid 1950s. They eventually twigged it, as the final versions of the delta wing aircraft had far fewer large fences than the prototypes. The MiG-19 thus represents a significant anomaly, although the only other aircraft with anywhere near the same aspect ratio/sweep combination was the Lightning, which had some lateral-directional issues in development, but was characterised by far superior handling qualities than it's Western contemporaries.

Edited August 13, 2014 by stephenmcparlin

[Do335 382]

hi Fubar! Thanks for the reply.

 

I'm more wondering about how it works with the data ini entries. Opened a new thread here

http://combatace.com/topic/83599-where-are-the-sizes-of-surface-areas-defined-in-the-fm-entries/

[Toryu 156]

@ Steve:

 

Do you know if there's any US test-flight reports about the MiG-19? 

I was at the german Air Force Museum at Gatow (might ring a bell or two with our british members here) yesterday. Whenever you guys are in Berlin, you should go there - it's free, but a little bit of a pain to get there.

Standing in front of the MiG-17s, MiG-15s and Su-22s they have there (quite literally standing next to a Sabre Mk.6), you can't do anything but wonder if the soviets had some kind of fence-fetish.

I wonder why they didn't try out thinner wings in combination with less sweep and slats, instead of using wing-fences all over the place. They did have lots of fighters with LE-slats during WW2, so the concept wasn't new to them.