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

[+streakeagle 865]

In what other sim could you have this fight over late 1950s Europe?

It was 2 vs 2. My wing died almost immediately as the AI isn't really programmed well to fly planes that go fast but can't turn. It was a game a patience trying to set up a shot without departing controlled flight. Altitude was always plenty high up for easy recovery. I came in fast from above, but throttled back and if necessary applied brakes to reduced range rate for targeting/firing. Eventually, the AI cooperates if you have enough fuel to wait it out. Took a while to bag the leader, but the proficiency gained doing so made it far easier for me to set up a firing solution on the wingman.

 

As presently modeled in SF2, the Voodoo is extremely difficulty to employ in a dogfight, but has quite a bit of power. With well trained pilots and sound tactics, it could even be reasonably effective.

[macelena 1,070]

When you don´t have much flight time with this sim, yuo get to prefer the tighest turning aircraft. One of the things i love of this sim is that it covers a period in wich aircraft were handicapped in some way or another. Fast and sluggish, slow but agile, and so on. You fight against you aircraft limited envelope as much as you do with your adversary. As i got more used to it, i got to appreciate more some underrated aircraft wich were impossible to use succcesfully before you knew them. The first plane i got used to exploit was the Phantom, then Mirages, and lately, i´m playing campaigns with F-100s and enjoying it when i couldn´t even imagine they could be any good. You just have to be smooth, cool with them. You don´t experience something like that playing with post 4th Gen aircraft in other sims. 

[+streakeagle 865]

There is no other sim that supports the Century series so well. DCS will never have this planeset (at least this century!). When I hosted and played SFP1/WoX online, quite a few of the people joining were somewhat new. So, I frequently flew the F-100D, F-104G, and A-4E while they learned to use the F-4 or flew much more maneuverable MiGs. With the advent of WoV, the F-105D was added to my stable of aircraft I could fly against newbies. Aircraft with major limits are fun and challenging for me. Though, it is nice if they have at least one strength that can keep you alive or even allow you a shot at winning.

[+daddyairplanes 9,012]

First thought on seeing the title..... zone 5 and run motherf....er!

[Toryu 156]

I've found that flying Jaguar A or F-100s (underpowered as hell) or similar jets, really teaches you to manage your energy. If you step up to airplanes with more power (albeit not necessarily more turning-capability), you'll feel like a bad mofo.

 

Usually, once either ammo or fuel are out, AI planes tend to fly straight and level to their homebase, which makes plinking them out of the sky pretty easy.

 

I guess the Voodoo is a great aircraft for learning to fly well - gotta re-install the fighter-versions and give it a try or two!

Edited June 30, 2014 by Toryu

[+streakeagle 865]

If you have the fuel to do it, having the speed/power to avoid the enemy until he runs out of fuel works in reality, too. Duke Cunningham's 1v1 with a MiG-17F in the vertical didn't end in a win because he outflew the MiG, it was because the MiG dove away and tried to extend, presumably to disengage. A number of MiG-21s went down to lack of fuel in the Middle East. Unlike SF1 AI, SF2 fighter AI does have a tendency to perform evasive maneuvers even after running out of fuel and attempting to head home.

 

But I can assure you that I was hearing stall sounds and/or departing to get my nose on the MiG-15s in an F-101. I think a falling refrigerator can turn inside a Voodoo!

[+Spillone104 553]

Actually the everlasting problem with the AI is another one. You can't catch them by surprise, And actually this was the key factor in many fights. In this case the Voodoo have a clear advantage having a radar and being way faster than the MiG-15. In SF2 they always spot you even if you are in their blind corner. And this always put the player in difficulty in this case. Plus, the stock FM for the AI MiG-15 and 17 is "just a bit" generous, giving them the ability to still fly with a swept wing at a mere 80Km/h in turns.
On the other hand the F-101 FM is VERY formative.

[+streakeagle 865]

TK went from one extreme to the other: the original AI always acted surprised (more like comatose) unless tasked with some sort of anti-air mission AND at the waypoint where the mission was supposed to take place. That caused tons of complaints from just about everyone that ever played the game from the original Walmart release of SFP1. So, rather than make some complex AI that carefully evaluated what each pilot should know and how they should react to that knowledge, TK went for the simple solution: make the AI see everything all the time. Blind spots specified in data.ini files are worthless: not used by the game. I like to design historical missions from Vietnam using the Red Baron reports, but I can't simulate surprise. The moment a mission starts, all the enemies approaching from blind spots are automatically called out and either evaded or attacked. Aircraft with bubble canopies are penalized by this behavior. However, this all-knowing capability makes almost every dogfight fun/challenging at the expense of realism. Despite the cheats and limitations, SF2 AI is pretty much the most interesting I have ever fought against. Give the AI a good turn fighter, or better yet an aircraft that has power and can turn, and the AI gives me a decent run for the money!

[Lexx_Luthor 57]

streak, you could set visibility distance to near zero, so planes are invisible to AI, and use maybe 360 degree radar cones with defined ranges to simulate varying AI visual capability. Of course, you lose the modelling of radar then. But if you are doing mainly visual engagement simulation, it should work, don't need radar anyways.

 

--

 

I've found, over the SF-1, that applying a non-standard waypoint behavior makes AI unresponsive to any fighter threat...say set a normal cruising waypoint as APPROACH for example. I forgot now which of the many non-standard behavior settings work best, but if you poke around, you should find one or two that can simulate, for example, some escort fighters refusing to respond to interceptors and so keeping their drop tanks until a "normal" waypoint, all while assuming other escorts in the mission take up the slack and are set to normal waypoints so the sleepy escorts and the bombers are not threatened.

Edited July 2, 2014 by Lexx_Luthor

[stephenmcparlin 8]

The F-101 had a fairly complete collection of non-linear flight mechanics nasties. I've heard the quote "Gentlemen, we may not have invented pitch-up, but we've certainly perfected it". I've seen the NACA free-flight rocket model reports, and I concur. The Voodoo is a beast: masses of power and straight line acceleration, no significant turning ability at low speed. It's similar to the F-104 in many respects, but it's heavier and even draggier.
 

The Vietcong and NVA used to set traps for RF-101s by stringing cables across the ends of valleys that they were known to transit in and out of the mountains to the west of Vietnam. The pilots would not be able to get enough pitch rate to escape over the ridges. Very nasty.

It's notable how poor the handling qualities of most of that generation of USAF fighter aircraft were. MIL-STD-1797A came into force as a means of getting manufacturers to design with handling qualities in mind. The F-86 (and particularly the later models, with slab tailplanes) had beautiful controllability, the F-100 was a dog, and the F-101 and F-104 were totally merciless towards pilot error. The F-102 and F-106 did have nicer handling characteristics, but their complex weapons systems were let down by the Hughes Falcon being unable to hit any target smaller than Nebraska. The F-105 was better than either the F-101 or F-104 in respect of controllability, but had a high wing loading. When encountering an air-to-air threat, you used the same tactics as an F-111, point the nose towards the cows and shove the throttles forward.

p.s. The only western jet I know that had even *worse* handling characteristics would have been the early models of Gloster Javelin, which had every vice under the sun plus some they'd invented specially. Indeed, the increased throttle-dependent drag when turning on the reheat system was greater than the extra thrust generated. This meant that when you pushed the throttle forward, the aircraft slowed down and the fuel gauge unwound as all that kerosene was converted to noise.

Edited August 8, 2014 by stephenmcparlin

[MigBuster 2,864]

 

p.s. The only western jet I know that had even *worse* handling characteristics would have been the early models of Gloster Javelin, which had every vice under the sun plus some they'd invented specially. Indeed, the increased throttle-dependent drag when turning on the reheat system was greater than the extra thrust generated. This meant that when you pushed the throttle forward, the aircraft slowed down and the fuel gauge unwound as all that kerosene was converted to noise.

 

Sounds about right!

[Toryu 156]

 

The Voodoo is a beast: masses of power and straight line acceleration, no significant turning ability at low speed. It's similar to the F-104 in many respects, but it's heavier and even draggier.

The 104 isn't draggy. In fact, it's pretty clean (no surprise there - nothing much there to create any drag), allowing a similar or greater range at low level, hi speed than, for example, a Phantom (a real gas-hog by the way!)

The same is actually true for the Voodoo. Also, neither aircraft (as far as I can remember) had any pitch-oscillation issues leading up ti APC/PIO at high dynamic pressures - unlike the F-4 which had stability-augmentation band-aids over it's relatively poor unaugmented flight-chraracteristics all over the place.

 

 

The F-86 (and particularly the later models, with slab tailplanes) had beautiful controllability, the F-100 was a dog, and the F-101 and F-104 were totally merciless towards pilot error.

A pretty short-sighted conclusion IMO.

Both, the F-101 and F-104 suffered from severe pitch-up. Pitch-up is, however, not unique to T-tail designs, but also plays a decisive role on other highly-swept wings (Sabre-Dance anyone?). What T-tails do, is making recoveries in steady-state conditions hard. A bad thing in theory - in practice, most aircraft went into gyrations (thanks to precession created by the pretty powerful gyro which the jet-engine in those fighters represented). This in-turn meant that pitch-ups in the 104 usually transformed into violent spins, from which recoveries could be made...or not.

 

The point about these behaviours is, that they're rather predictable. Exceed x degrees (or units) of AoA and you'll find yourself in a wild ride. Nothing special there, as other aircraft behaved similarly upon deperture, providing much less of a warning (F-8, F-100, etc.) and fewer ques.

Apoart from pitch-up (and maybe some BLC-issues in the F-104), those airplanes were relatively straighforward in handling if you just didn't go into indian-country with your AoA (inertia-coupling during quick rolls is another topic, but most pilots won't go there to often, as it's pretty uncomfortable on your neck).

 

In short, the F-101 and F-104 had pretty clear boundaries between "flying" and "being in for the ride".

Those boundaries are tighter than on other airplanes, makeing them less useable - granted!

But it also makes it easier to stay out of there - other planes (F-8, F-100, etc) will let you get away with more. But they'll get interesting suddenly when flying at high AoA and the warning provided by the aircraft (no stick-shaker that is easily detectable) may not be enough of a hint to pilots with different backgrounds. Their handling is less "digital" (either "flying" or "not flying") and thus harder predict for less experienced pilots or pilots transitioning from other airplanes.

Granted, pilots will always need a lot of time on the airframe to fly it proficiently and efficiently.

 

The F-100 kind of was a dog (more than 800 non-combat crashes during normal operational flying), but it actually didn't handle that badly (adverse yaw was a factor on most airplanes these days - the F-104 for example just wouldn't achieve high enough AoA to experience it, so it wasn't a problem there). It lacked thrust, but that wasn't an issue isolated to the F-100. Many pilots still remeber it fondly.

 

All of that cut short: Most aircraft are getting dangerous when flying outside the numbers quoted within SOP. Some aircraft will let you get away with more stuff than others. The F-104 did'n experience that many "pilot error" accidents that were unique to F-104 characteristics. Most of the pilot-error stuff was issues that will kill any pilot in any airplane (CFIT).

What made many early crshed on the F-104 unnecessarily deadly was the crappy ejection-seat. Most other aircraft of the time had Martin-Baker seats with a higher survivability rate due to the much greater ejection-envelope (particularily in the "low and slow"-regime).

 

 

The F-102 and F-106 did have nicer handling characteristics, but their complex weapons systems were let down by the Hughes Falcon being unable to hit any target smaller than Nebraska.

Many people involved with the Falcon claim that it was generally a better missile than the Sidewinder. What it made it suck was both, the complex switchology and the hit-to-kill warhead.

 

 

The F-105 was better than either the F-101 or F-104 in respect of controllability, but had a high wing loading. When encountering an air-to-air threat, you used the same tactics as an F-111, point the nose towards the cows and shove the throttles forward.

The F-104 (when used as fighter) was considered the best aircraft in US-inventory below 20000ft (ref. "Project Featherduster"). It had about the same turn-capabilities at high speeds as an unslatted F-4. At low speeds, it sucked - but it wasn't designed for knife-fights in a telephone-booth.

The F-104 featured superior controllability at high speeds to most other airplanes, thanks to it's high roll-rate, making it able to quickly point it's lift-vector into another direction. It would also accelerate quickly when unloaded. It's SEP was phenomenal for the early 60s.

The later flap-limits (lower to T/O up to 450KIAS/ M0.85, extended up to 540KIAS/ M0.85) made it turn rather well at speed.

 

 

Indeed, the increased throttle-dependent drag when turning on the reheat system was greater than the extra thrust generated. This meant that when you pushed the throttle forward, the aircraft slowed down and the fuel gauge unwound as all that kerosene was converted to noise.

Would you care to elaborate that phenomenon?

 

___

BTW: If you'te looking for interesting flight-characteristics, the Jaguar might be high on your list. Underpowered, unsufficient tail-area, a tendency to stall the engines and some very interesting roll-coupling autorotation-modes. Most pilots liked it anyway.

[stephenmcparlin 8]

I've read the test pilot reports on all of the above... I'm actually an aircraft designer. :-) You may be able to find my AIAA White Paper on handling issues online somewhere. I'm not going to quote classified sources on an open forum, but I have read them. In the case of the F-104, the basic zero lift drag is *very* low, but the wing has a horribly low aspect ratio (subsonic lift-dependent drag) and a sharp leading edge (flow separates at very low CL). The unswept wing layout also contributes to very high lift-dependent wave drag at supersonic turn conditions. I'd suggest you read Dietrich Kuchemann's "The Aerodynamic Design of Aircraft" to get an idea of drag dependency on configuration. Other useful sources on supersonic drag include NACA reports 1284 and 1335, both by R. T. Jones.

 

Steve

 

Oh, and throttle-dependent drag: Base pressure is a major factor in zero-lift drag, increasingly so at supersonic Mach number. The best UNCLASSIFIED reference I can point you at is Charlie Boppe's Von Karman Institute lecture notes on Drag Estimation and Prediction, part of AGARD-R-783, which cn be downloaded from the NATO RTO website. In the case of the Javelin, the combination of a large, flat, base and the pressure drop in the base when the reheat kicked in resulted in a larger drag increment than thrust increment.

Edited August 9, 2014 by stephenmcparlin

[Streakfalcon 57]

MMMmmm yes indeed, I find NACA reports shallow and pedantic... indeed

[+streakeagle 865]

Robin Olds flew the Voodoo. He actually used it to perform a formation air show (think Thunderbirds). It wasn't agile by any means, but it didn't just fly in straight lines either. He also had a very low opinion of the AIM-4 Falcon. However good the Falcon looked on paper or in staged tests, it took too long to fire, had even more limited launch parameters than the AIM-9B and early AIM-7s, and was rarely able to hit a fighter sized target. The Falcon might have been effective in its intended role of heavy bomber interception at altitude, but it was (thankfully) never employed in that role, so there is no real world data to confirm whether it would have worked as well as advertised. 

[Toryu 156]

 

In the case of the F-104, the basic zero lift drag is *very* low, but the wing has a horribly low aspect ratio (subsonic lift-dependent drag) and a sharp leading edge (flow separates at very low CL).

The low attainable CL in clean configuration is worked-around by the availability of hi-lift devices up to M0.85. In this case, the LEF deploy to 15° and the TEF also deploy to 15 or 20° (forgot the exact number). Depending on the version and engine insatalled, the F-104 manages to attain a similar sustained G as an unslatted F-4 at speeds above 420KIAS. SEP is also relatively close between the two when above 400KIAS at low-med altitudes.

 

Fun Fact: The F-104's L/Dmax is actually grater than the F-4's.

 

BTW: On the F-104, the fuselage amounts to roughly 50% of the net-lift at higher AoA.

 

 

The unswept wing layout also contributes to very high lift-dependent wave drag at supersonic turn conditions. I'd suggest you read Dietrich Kuchemann's "The Aerodynamic Design of Aircraft" to get an idea of drag dependency on configuration. Other useful sources on supersonic drag include NACA reports 1284 and 1335, both by R. T. Jones.

I did some calculations about a similar problem for a Mach 4.4-cruising space-launch system a couple of months ago, so no need to dig up 'ole Küchemann.

 

The unswept wing of the F-104 creates a supersonic leading-edge, which is unsexy indeed. Therefore, however, they gave the leading-edge a very sharp radius (well, almost no radius at all), to minimize drag of this wing-configuration. I'd hazard the guess that the sharp leading-edge actually leads to lower overall wave-drag than of contemporary fighters with a subsonic leading-edge and a much thicker wing/ blunter nose-radius. The trade-off was the need to apply BLC on the TEF for attaining manageable landing-speeds (180KIAS with the flaps at LAND, 220KIAS in final-approach with the flaps at T/O!)

 

You'll also know that due to the AC's shift at supersonic speeds, G avilable also shrinks down. I don't have actual figures on the shift of the pitch-moment at hand, but I'll expect the shift on the F-104 to be smaller than on contemporary designs, due to the comparatively small size of the wing (small chord-length and thus small change in pitch-moment resulting due to the AC-shift).

 

I also don't have the max avial-g figures of the F-4 at supersonic speeds at hand (I might ask a buddy who flew the F-4F and probably has the figures out of DASH-1 still memorized, though).

A Mirage III can not attain more than 2.5 to 3g (also due to shock-induced pressure loss around the elevon-hinges) at Mach 2. I don't expect the F-4 to be able of attaining more than 3-4g at supersonic speeds, either.

 

Thus, the overall resultant drag is not as important as one might think: With g-avial being low, the turning radii-large and fuel-consumption astronomical, supersonic turning is not that much of a deal. What's more important is transonic acceleration and SEP.

 

 

Robin Olds flew the Voodoo. He actually used it to perform a formation air show (think Thunderbirds). It wasn't agile by any means, but it didn't just fly in straight lines either. He also had a very low opinion of the AIM-4 Falcon. However good the Falcon looked on paper or in staged tests, it took too long to fire, had even more limited launch parameters than the AIM-9B and early AIM-7s, and was rarely able to hit a fighter sized target. The Falcon might have been effective in its intended role of heavy bomber interception at altitude, but it was (thankfully) never employed in that role, so there is no real world data to confirm whether it would have worked as well as advertised.

 

Streak, I know those stories as well. Olds wasn't wrong at all - missiles should be simple and they should provide easy solutions for the pilot instead of creating problems.

There's a quote of a programm test-pilot on the Falcon in one of the F-4 books I have. He states that the Falcon per se was the superior missile (better seeker, higher maneuverability than the Sidewinder models at hand at the time), but it indeed was designed for intercepts with a relatively narrow cone of firing and relatively long time available for switchology and procedures (cooling the seeker, etc.). It really wasn't a dogfight-missile in it's incarnation at the time (or any time later, for that matter).

In the end, it all came down to the Air Force wanting to have an Air Force missile, replacing a Navy missile hanging on their Navy airplane. There was also inner-USAF issues with one command insisting on keeping the Falcon and one insisting on the Sidewinder.

Politics at it's best...

Edited August 10, 2014 by Toryu

[macelena 1,070]

I can´t discuss in any of the topics dealt with here with my limited knowledge, but i just checked the wikipedia AIM-4 page again. Apparently, the Falcon achieved 5 kills out of 54 missiles fired, so its Pk isn´t as bad on paper when compared to contemporary missiles. However, i don´t know if those 54 firings reported included missiles failing to leave the rails or left useless by the seeker going out of coolant. Apparently, the issues were adressed with the XAIM-4H, but it remains weird that no iniciative allowed for those improvements to be ready before deploying the weapon since, apparently, there were many concerns on their use. Again, complacency loss of focus by some commanders seemed to be an issue regarding this.

[stephenmcparlin 8]

The aerofoil on the F-104 is actually a 3.5% thick biconvex section, which is what you get if you only have 2D design methods, which was the case before around 1954. The fuselage lift comes from development of vortex flow on the forebody, which becomes the dominant factor in the subsequent nose slice and flat spin as AoA increases. Theres an interesting comparison with the F-5 and T-38, which also have an elliptic fuselage cross-section, but with the primary axis horizontal, rather than vertical, as in the F-104. Slab-sided forward fuselages are a very bad idea for directional stabilty at higher alpha, something seen on the F-4 and F-8 as well as the F-104. The worst I've seen is actually the A-7, which has relatively less inertia about the yaw axis, so develops a spin very quickly on departure. Rule of thumb for shift in aerodynamic centre with Mach number is that it progresses from 25% mac to 50% mac between drag rise onset and the leading edge going supersonic. Because of the short chord, the physical shift in c.g. will be small. I'd estimate a static margin of about 6% for the F-104 subsonically, which implies about 31% at supersonic conditions. The F-4 did have the ability to pump fuel fore-and-aft, depending on flight condition but I don't know whether there were any comparable rules for c.g. management in the F-104.

There is published SEP data for the F-4E, showing that it has a 4g STR capability at M=1.2 at the tropopause (corner point for the F-4 is supersonic). Supersonic SEP is hugely important for BVR combat, as it's a major factor in no-escape zones for head-on engagements. The F-4F was unique in losing BVR capability until the mid-life upgrade restored it. My former section head at RAE Farnborough, Dr A Jean Ross, did a very thorough analysis of the transonic nasties present on the F-4 (wing rock was possibly the most disturbing to the pilots), while Air Commodore Dave Best, former head of ETPS, was seconded to RAE to work with us when he was a young test pilot, back in the early days of Typhoon, told me many hairy stories of time on Phantoms, both as a test pilot instructor, and on operational squadrons.

The supersonic manoeuvre limit on the Mirage III is, as you suggest, due to progressive lack of trimmable lift coefficient at higher Mach, although this is more due to the high static margin than loss of control power. I know that Dassault played around with relaxed stability on the Mirage 50, but I don't know if they implemented a fully longitudinally unstable FCS before the Mirage 2000.

[Toryu 156]

I think the yaw-stability is not that much an issue on the F-104, as it reaches it's pitch-up boundary somewhere around 22° AoA, where most conventional swept-wing aircraft still do have some AoA-margin available. It most-probably will depert violently, but that is primarily due to the engine acting as a precessing gyro. Interestingly, the A-7 recieved maneuvering-flaps later in it's career, which supposedly cured it's nasty departure.

 

The shift of MAC is naturally also dependant on the basic geometric shape of the wing. A delta-wing will have it's CoL shift up to around 67% root-chord, while a basic, unswept flat plate will go for 50%. Both values are theoretical, of course, and only act as first approximation.

 

I know the F-4 had lots of tanks in a longitudinal arrangement (and the Echo had a 7th tank - something the F-4F lacked), but I'm not sure about the CG shifting capabilities. The british Phantom (courtesy to it's Spey engine and the required fuselage-modifications) did have a different volume-distribution*, leading to larger wave-drag and thus generally a lower performance closte to the Mach or beyond, despite the more powerful engine (on paper - don't know the dynamic thrust curves at high Mach and/ or altitude - being a turbofan, the Spey had to give some performance away in that realm).

 

The Mirage 50 was an Mirage 5 with the F1's Atar9K-50 (hence the name) and either an Agave radar (taken from the Super Etendard, for the ground-attack version) or with a Cyrano IV radar (taken from the F1, for the A-A version). The versoin you mean is the Mirage IIING, which had a couple of modifications, large (non-moveable) canards and the FBW-System of the Mirage 2000. They squeezed-out about 2 more available g throughout most of the flight-envelope. Much of that comes from the canards alone, however, decreasing the stability margin.

Interestingly, sevral parties have develloped ther own canard-versions for the Mirages. The swiss canards, for example only have about 70% of the israeli canards' area.

 

Referring to the Javelin:

I've read several different accounts of why the afterburner didn't quite work out.

One was the absence of divided fuel lines, whith the afterburner-pump bleeding off too much fuel from the mainline fuel-lines, thus leading to a diminished fuel-flow to the combustion-chamber.

The other one was the abscence of a con-div nozzle, making the jet-pipe choke.

The third one is your explantaion, which I haven't quite come to understand properly, yet. As I understand it, you're talking about the boattail-effect with the exhaust-nozzle having the wrong shape for the resulting pressure/ flow-distribution with an engaged afterburner, thus creating a large amout of drag there.

 

A very interesting discussion, by the way!

___

* Basicly, it was down to the intakes being a good portion larger and the engine-bays being a lot more voluminous.

Edited August 10, 2014 by Toryu

[stephenmcparlin 8]

Afterbody drag is a big deal for most modern combat aircraft, particularly supersonically. Some are worse than others. Charlie Boppe of Grumman was particularly keen to point out that the F-14D had superior supersonic performance to the F-15, largely because the latter had a very high throttle-dependent drag and much bluffer boat-tail (corresponding to about 50% of zero-lift drag at supersonic conditions). High fuel burn at supersonic speeds was tactically limiting on the F-15, when trying to chase down Iraqi MiG-23s escaping to Iran. The F-14 and Tornado F3 were inconvenienced far less, due to their lower supersonic drag.  It's also the case that relatively few fast jets actually have convergent-divergent nozzles, with most relying on a simpler, lighter convergent nozzle and accepting the thrust penalty of an underexpanded jet. The PW F100 and GE F110 engines both have these as standard, as does EJ200 on Typhoon. The F404 engine on the F/A-18A-D does not, I think.

Working with a convergent nozzle implies a choked flow at, or just beyond, the nozzle exit (effectively the shear layer on the inside of the nozzle pushes the boundary out). Varying thrust then requires a higher mass flow (or rather, nozzle pressure ratio) or nozzle area. The trade-off is determined by external drag of the nozzle plus the associated mass.

[+CrazyhorseB34 937]

Dude, I can tool every 60's American jet in the air with the MiG-15Bis with Fubar's flight model in this sim. Just have to be a smart Ivan. Since no other medium let's you do this I would say that it all depends on the dude holding the stick.

 

Same way I tool Israeli F-15's and F-16's with MiG-23's.

 

Stay low....radar off....GCI vector....merge low masked by ground clutter..... zoom climb...radar on....... boom and zoom.... radar off... rinse and repeat.

Edited August 11, 2014 by CrazyhorseB34

[Toryu 156]

Doesn't the convergent nozzle rely on an underexpanded flow anyway? With the nozzle being convergent only, the exhaust jet can reach Mach 1 at max (which is much higher than Mach 1 in the ambient air, due to the temperature of the exhaust-jet). Thus, in order to expand into supersonic flow, it needs the nozzle-area to be increased behind the throat.

IIRC, on most nozzles this is achieved by secondary air and a secondary nozzle, but some aircraft (eg. Tornado, Mirage IIIC with the Atar 9B with an eyelid-nozzle) obviously can do without the seondary nozzle.

 

With the afterburner-jet being accelerated up to Mach 1 (which is higher than Mach 1 in the colder, ambient air), this might actually enough to attain a velocity of Mach 2, if the exhaust is hot enough.

The trade-off would be a really bad underexpanded exhaust-jet.

 

At 40,000ft, a sonic exhaust-jet with equal velocity of Mach 2 of the ambient air would have to be at ~600°C at the throat area - that's by using a=sqrt(gamma*R*T). Now, I don't feel quite happy by calculating isentropic through an afterburner-nozzle, but it gives us a first shot to make a guess.

 

 

Dude, I can tool every 60's American jet in the air with the MiG-15Bis with Fubar's flight model in this sim. Just have to be a smart Ivan. Since no other medium let's you do this I would say that it all depends on the dude holding the stick.

Seems to me that you can always drag the AI into a knifefight. They're not really into using their strenghts (except that means rolling their lift-vector on the enemy and pulling some Gs).

Edited August 11, 2014 by Toryu

[+CrazyhorseB34 937]

True about the AI. Wish we could tweek that a tad.

[stephenmcparlin 8]

The total pressure in the jet should *always* be higher than ambient at the exit, hence when running with a fully-expanded jet, there is no pressure difference across the free shear layer surrounding the jet stream. The diamond patterns in the jet efflux are caused by the reflection of shock and expansion waves until ambient pressure is reached. Nozzle pressure ratio is a key performance parameter, as the excess pressure ratio beyond unity is a measure of the residual momentum of the jet. Most of that excess pressure is converted into momentum. Kuchemann and my old colleague and neighbour, Dr Johanna Weber, worked out most of the aerodynamics of jet propulsion at Goettingen, Volkenroede and then Farnborough in the mid-1940s. There is no mechanism here for attaching files, but I produced a pdf of the relevant equations on propulsion that I provide to undergraduates doing one of my Aircraft Design Modules at universities in the UK.

[+streakeagle 865]

There isn't a fighter plane in the SF series that I can't beat with any other fighter plane in the series. AI is a huge factor, but having played SFP1/WoX online for a few years, I could rack up kills against much better planes while flying F-100Ds, F-105Ds, and F-104Gs. A good plane alone is worth little without a smart, well-trained pilot to employ it correctly. Doghouse flying a MiG-17 was virtually unbeatable. The king of early SFP1 online dogfighting was the MiG-19... turned about the same as a MiG-17, and accelerated/climbed better than an F-4 or MiG-21 in the vertical. Yet I could defeat MiG-17s and MiG-19s while flying the way underpowerd F-100D when they were flown by lesser pilots or AI.