MiG-9 WIP

[Lexx_Luthor 57]

Better... CD0MachTableData=1,1,1,1,1,1,1,1,1,20

 

Okay, landing speed is too high. Must figure this out.

[Lexx_Luthor 57]

Wing Cla seemed to fix the landing speeds. Now, takeoff run is a bit short and climb rate is a bit high -- and fluttery -- I think I climb a tad too well at fairly low airspeeds, and I should not.

 

Also, I found no way to really control how top level speed varies with altitude. For the MiG-9, I would like...

 

0km -- 860km/hr

5km -- 910km/hr

10km - 850km/hr

 

I have good results except for the sea level speed being higher than 900km/hr.

 

Both issues might be addressed by the following: The sea level speed is above 900km/hr. I'm thinking, maybe early turbojet engine static thrust peaks at some altitude above sea level, although every aircraft FM I've looked at, both 3wire and 3party, all have the engine altitude table max of 1.000 at sea level. Maybe that max static thrust should be at above sea level. Probably not, but if so, would this be correct thinking?

[Lexx_Luthor 57]

Nap, the links I found all state turbojet thrust decreases with altitude. I guess I was thinking of air temperature which does effect fuel consumption in a positive way with altitude, or so I figure. Now, the DryMachTable would offer a method of increasing takeoff distance, as it seems that max thrust happens at higher speed than zero.

 

I wish TK would offer a specific fuel consumption altitude table.

[+nele 0]

Well, there is one more thing-that is inlet drag . You always have a difference between installed engine and engine on a testbed. Could be neglible, but exists, even in static conditions.

 

Thrust drops with altitude, but grows with speed. The curve of both are hardly straight lines.

 

I tweaked dry and wetmach alot for MiG-23's and experimental Foxbat, but it is not good for low speeds. The reason is you get mucho thrust in flight where there should be little-static (at the top of the loop-or while doing a "bell").

 

Also, AI can get stupid (or "smart") and use it for turning fight on the heel

 

Nele

[Lexx_Luthor 57]

Thanks nele.

 

I'm flying this thing only on "hard" and the AI also seems okay with what I have so far. I have not tried AI landing yet. I'll have to see what happens. I'm ready to wrap this up. Its my first learning FM and I've gutted a number of variables and tables that I didn't see make much difference for my purposes (uh oh). I can always add these back later.

 

Timmy's missing. There were some skin modders who had the MiG model. They could be used for testing FM for me.

[+Timmy 1]

Not missing my brother, just caught up in the swirling, sucking eddy of dispair filled with brief glimpses of hope and light in an ever darkening universe that is my life...

 

I should be back on track in a day or so (Good Lord willin' and the creek don't rise.)

[Lexx_Luthor 57]

Hi Timmy. Yea I'm still tweaking but enough is enough for now.

[Lexx_Luthor 57]

Ah, raising these just a bit helps lower the landing speed.

 

AlphaStall=18

AlphaMax=20

AlphaDepart=22

[+Timmy 1]

If anyone who received the MiG-9 pack from me has a copy of the skin "soviet2" will you please send a copy back to me... Another genius move seems to have befallen your fearless skinner as I no longer have the lightning bolt portion of the nose. Ah, well - I suppose I can always make a new one...

 

BTW - release date is... Very, very soon.

[+suhsjake 11]

Good to hear Timmy. You and your team keep it up.

[Lexx_Luthor 57]

I'm doing deeper experiments in simplifying. I'm trying to eliminate the left/right OuterWings as aerodynamic objects, but the 3D model requires they still be used for other purposes.

 

(1) Less complex means easier to learn. I am seeing that both 3wire and 3party FMs copy and paste much of the A-4B data for wings. This indicates excessive complexity is being side-stepped.

 

(2) The less complexity, the easier to generate correct overall behavior and correct relative FMs between different aircraft.

 

(3) To save cpu performance if hundreds of aircraft fly across a game map populated with corresponding air defenses during, say, a mass strategic air strike against Siberia, for a purely random example.

 

(4) The more I learn, and I'm only just starting out, the more complexity I can add to the FM. Right now, my file is just over half the size of a "normal" FM file. The thing is, I can delete a wad of stuff from most FM files and not see any difference in handling, feel, or performance. Other stuff, of course, must be used as core, and some are very tricky and present surprises if deleted.

 

(5) The less complexity means its easier to add in some extra complexity as desired to attempt modelling behavior that may be unique to some aircraft.

 

 

So I'm now experimenting with using just LeftWing and RightWing, but using the outer wings for things like vortex and child control surfaces (ailerons). I started using a more interesting CDL table formula. Alot of FMs just copy the parabolic A-4B formula -- CDL(a) ~ (a^2). I like this better...

 

CDL(a) = 0.5 [e^(0.2a) -1 ] ... the table looks like ... CDLAlphaTableData=200,74,27,9.5,3.2,0.86,0,0.86,3.2,9.5,27,74,200 with 5 degree data bins -- easier to count out than 4 degree bins. I wanted more energy bleed in tight turns, and this helps.

Edited October 3, 2007 by Lexx_Luthor

[Fubar512 1,350]

Alot of FMs just copy the simple parabolic A-4B formula -- CDL(a) = (a^2)/(16) . I like this better...

CDL(a) = 0.5 [e^(0.2a) -1 ] ... the table looks like ... CDLAlphaTableData=200,74,27,9.5,3.2,0.86,0,0.86,3.2,9.5,27,74,200 with 5 degree data bins -- easier to count out than 4 degree bins. I wanted more energy bleed in tight turns, and this helps.

 

What, you have something against CDLalpha tables made up from multiples of from prime numbers?

 

Keep in mind that straight-winged aircraft would tend to have lower Cla values at either extreme of the table, as they do not generate as much lift at high angles of attack, as would, say, a delta winged aircraft.

 

Out of curiosity, and since you're using "single wing" entries, did you position the Xac tables along the mean area chord of both wings and the horizontal stabs? If so, where did you calculate the starting coordinates of the tables from?

[Lexx_Luthor 57]

Fubar THANKS for the CLa swept wingtip. I have wing Cla as constant right now. Other FMs have Cla that vary little over the flyable speed range (tables often extend far beyond max Mach), so I keep it constant for now. The high supersonic FMs do seem to have great CLa variation at higher speeds. I am TOTALLY subsonic right now. I want to do B-29 next as its very FM heavy and I want large formations, and it would be a good learn for heavy aircraft.

 

My Xac tables are all constant until I start using them over the Mach range. I now have my L/R wing Xac positioned (=0.10) so I get a fairly smooth takeoff on the one wing but that could easily change with other changes.

 

Question: In these ancient heavy metal fighters, like say F-84, how much pitch down did the pilot get by lowering flaps all the way?

[+nele 0]

Uh, I cannot help you with Thunderjet, but MiG-9 flaps were not overly efficient.

 

Is it possible to "install" transsonic behavior in aerodynamic model(s) of those early birds? Elevator lockups, aileron reversals, pitch-ups, pitch-downs, vibrations... any current model with that?

 

Nele

[Lexx_Luthor 57]

Thanks for the flaptip nele.

 

nele::

Is it possible to "install" transsonic behavior in aerodynamic model(s) of those early birds? Elevator lockups, aileron reversals, pitch-ups, pitch-downs, vibrations... any current model with that?

Oh yeah...I've got near-sonic vibrations and elevator lockup nailed...and several methods are available...and one method I've found (elevator cmdc) offers game-induced variation of vibration with altitude in addition to airspeed -- that would be one way of ensuring a rough high speed penetration ride at low level. A large change in Xac value should offer pitch problems at a specified Mach number, but I have not gone there yet. Aileron reversal would be nice for Yak-28.

 

Also, czech out Fubar's FM for MiG-17F near-sonic behavior.

Edited October 3, 2007 by Lexx_Luthor

[Fubar512 1,350]

Lexx,

 

I believe that you misinterpreted what I said. While CLa is represented as a constant, the CLa Mach table allows you some latitude in tailoring that (or fudging, it depending on one's perspective). For example, on a subsonic bird, I might declare a CLaMachtable like so:

 

CLaMachTableNumData=10

CLaMachTableDeltaX=0.10<----in .10 Mach steps

CLaMachTableStartX=0.00

CLaMachTableData=0.674,0.827, 0.923,1.000,1.003,1.012,1.143,1.070,1.054,1.059

[Lexx_Luthor 57]

Correct Fubar. I use "constant" CLa -- one value -- thus not using a CLa table to vary it, until I learn more what it does and how to use it profitably.

[Fubar512 1,350]

Just for grins, I plugged some figures into Kreelin's Aeroconvert (calculated off an accurate scale 3-view drawing of the MiG-9), and came up with the following values:

 

CLa= 2.314 (per wing)

Ymac= 2.222

mac= 1.768 (reference chord)

 

While I did not find any resources dealing with stall speeds for that particular bird, most of the straight-winged jets of the time had stall speeds within a few knots on either side of 90 kias (clean).

[Lexx_Luthor 57]

Fubar::

Just for grins, I plugged some figures into Kreelin's Aeroconvert (calculated off an accurate scale 3-view drawing of the MiG-9), and came up with the following values:

 

CLa= 2.314 (per wing)

Ymac= 2.222

mac= 1.768 (reference chord)

 

While I did not find any resources dealing with stall speeds for that particular bird, most of the straight-winged jets of the time had stall speeds within a few knots on either side of 90 kias (clean).

Woe Not bad. I'm using Cla=3.0 for Left/Right wing, and a Ymac=2.0 which are rough rounded guesses. I don't have a "mac" or reference chord. What are Ymac and mac? And what's with the significant digits in all the FMs? I always wondered if such precision indicated accuracy. If not, we can round and simplify wad of data.

[Fubar512 1,350]

mac = Mean Area Chord, Is used as Reference Chord=x.xx under the aircraft data section. It's also the area of the wing surface from where one would calculate the Xac tables from. Usually a range starting 25% of the distance along a longitudinal line drawn along the mac, aft from the leading edge (LE), and ending 60-70% of the way back from the LE along the chord.

 

BTW, calculate the the coordinates fore or aft of the centerline using an accurate three view for reference..not the 3D model.

 

Ymac = The mean area chord as represented along the "Y" axis, measured out to either side of the centerline of the aircraft(left=-value, right=+value).

 

And yes, the 'significant digits do matter.... if you're taking the trouble to do it, why not do it right?

 

BTW, Kreelin's Aeroconvert is under utilities, in our downloads section.

[+Timmy 1]

Soooo... I'll wait a bit longer to release prior to the final FM. The present one is a booger compaired to what I had been flynig (Two Allison J33-A-35's pushing her around.)

[+suhsjake 11]

That's funny, US Engines in an Russian Aircraft, OR is it?

[Lexx_Luthor 57]

British engine in the Ussian plane. German engines in the Russian plane.

 

Thanks Fubar, I'll look at the kreelin aero program.

 

 

---

 

Timmy, I'll be tinkering with this forever, so whenever you want it, take it. What cockpit are you using?

Edited October 4, 2007 by Lexx_Luthor

[+Timmy 1]

It has the Meteor F8 pit in it now and since I didn't make that one - I removed that folder and listed in the Read.me file that if they had that pit to put it in the MiG-9 folder - and if not to put some other pit in that folder and change the Data file to reflect that change.

 

I don't have any interest at all in creating cockpits - in fact, I don't fly with the cockipt enabled so it's obviously no big deal to me...

 

I'm making an executive descision and releasing it today.

Edited October 4, 2007 by Timmy

[Lexx_Luthor 57]

I would suggest the stock A-4B cockpit, although I'd like to modify the cockpit file first. In fact, I wouldn't mind Sovietizing the instrument panel. I like the A-4 for the round forward canopy frame -- very classic of that era. Another advantage is the A-4 is already in SF and WoV (don't know about WoE). Owners of only WoE would be in a pickle however.