AVSIM Commercial FSX Aircraft Review

Lockheed P-38 Lightning

Product Information

Publishers:  FlightSim Developers & SkyUnlimited

Description: World War II-era twin-engine prop fighter.

Download Size:
FSD - 406 MB / SU - 133 MB

Simulation Type:
Reviewed by: David Wilson-Okamura AVSIM Senior Staff Reviewer - December 14, 2009


The Lockheed P-38 was designed in the late 1930s to be a high-altitude interceptor. Production began in 1941, before Pearl Harbor, and continued through the end of World War II. German pilots called it the “twin-forked devil,” because of its double tail booms. But its engines fared poorly in the cold, damp climate of Europe. It was valued for reconnaissance and for attacking ground targets, but on escort missions and against German fighters, it was disappointing.

FSD Lightnings over Germany
FSD Lightnings over the Pacific

Meanwhile, commanders in the Pacific were clamoring for machines and materiel; this is where the Lightning proved its truth. Both of America’s top aces, Richard Bong and Thomas McGuire, established their records in P-38s, which the Japanese called “two planes, one pilot.”

The Lightning was fast -- capable of speeds in excess of 400 miles per hour -- with good forward views and heavy armor. Unlike most Allied fighters, whose gunfire converged at a fixed distance, the Lightning clustered all of its guns in the nose; this allowed it to concentrate fire at distances both long and short. It could carry rockets under its wings, or bombs under its fuselage; a few Lightnings were even equipped to evacuate casualties. Most remarkable of all, the Lightning was one of a very small class of fighters that could engage in a successful turning fight with a Japanese Zero.

This was discouraged -- the official tactic of Allied fighters in the Pacific theater was boom and zoom -- but it was possible. This was in part a feature of having two engines: by extending his maneuvering flaps, and then by giving more power to his outside engine, a pilot could “push” his aircraft harder into a turn.

SU Lightnings defend the Aleutians

The Lightning has been available in Flight Simulator for some time. If you go to the Just Flight website, there is a payware model with a free demo. It works in FSX, but the model was compiled for FS2004.

What we didn’t have, until this fall, was a P-38 model that was developed specifically for FSX, using FSX tools and features. Then, all of a sudden, there were two products, from two different publishers: FlightSim Developers (FSD) and SkyUnlimited (SU). The SU Lightning came out in September and sells now for US$21; it includes four different models and sixteen different liveries. The FSD Lightning appeared just a week later and sells for US$26; it comes with three different models and eight liveries, including a restored version with modern avionics. As of this writing, both products have been updated once. This review will consider the two products side by side.

Test System

Core2Quad Q6600 @ 2.4 GHz
4 gigabytes RAM
Nvidia 8800 GT (512 Mb)
Samsung 20” widescreen LCD (1680 x 1050)
Windows 7 (64-bit)
TrackIR 3 with Vector Expansion
CH pedals, yoke
Saitek X45 throttle
Sidewinder Precision Pro joystick
Sound Blaster X-Fi XtremeGamer sound card
Logitech X-540 5.1 speaker system

Flying Time:
15 hours

Installation and Documentation

Installation of both products was painless and automated. SkyUnlimited’s product is protected by the well known Flight1 wrapper. FSD uses its own anti-piracy scheme. In my experience, if there’s going to be trouble, it usually occurs when you need to reinstall something -- which I had to do recently, when I upgraded to Windows 7. With both products, the reinstallation went smoothly with no hiccups.

What about documentation? SkyUnlimited comes with several short PDFs, most of which are concerned with the history of the P-38, as recounted on the p-38online.com website and reprinted by permission. A longer PDF, derived from an original, late-model Pilot’s Operating Handbook (POH), provides a checklist for all phases of flight and for emergency procedures. Finally, there is a description of the features that are particular to this model.

The FSD manual has less information on the P-38’s history, but more illustrations, including cockpit diagrams, performance graphs, and some cartoons from the original training materials. Again, most of the text is in the form of checklists, and comes from a vintage POH. In addition, there are three manuals for the avionics suite in the restored “Red Bull” version. These total almost one hundred pages and cover the Garmin GNS 480 GPS, the Bendix/King KFC 225 autopilot, and the Garmin SL30 nav/comm transceiver. All three instruments, with their accompanying manuals, were developed for earlier FSD product.

Both products, SU and FSD, include kneeboard checklists; the FSD model also includes a kneeboard reference page, with graphs from the manual. The FSD kneeboard is easier to read, chiefly because it’s formatted in a larger font. But both models use the kneeboard and that’s appreciated.

External Model

Ironically, the exterior models for both products were both created by the same person, Kevin “Gibbage” Miller. How did this situation arise? The SU model was originally created for FS2004 (and you can still buy that version for US$15). After Miller moved on, Stephen “Stiz” Barstow recompiled the model for FSX, retagged the animations, converted the texture calls to use the more efficient DDS format, and added bump mapping. He also created 3D gauges, which we’ll talk about later.

Miller, meanwhile, was not standing still; like Barstow, he was learning new tools and honing his craft. The result -- what he has learned about modeling since his original Lightning for SkyUnlimited-- is the FSD P-38.

FlightSim Developers SkyUnlimited

Does this mean the FSD product is better? The external model is better, yes. The original modeler thinks so, and so will you after you study these screenshots. The differences can be summarized under two categories: 3D structures and textures.

As a rule, the FSD structures are smoother and more articulate. Textures are more reflective, colors are richer, bump mapping is more subtle, and details are sharper. On the SU fuselage, stenciled writing is blurred; on the FSD fuselage, it is legible.

FSD close-ups

That being said, Miller did a good job the first time around. Now that Barstow has added bump maps, his original model still looks good, comes with more liveries, and includes a recon version, F-5E, that’s not available in the FSD package. The SU product, though it falls behind in quality, inches ahead in quantity.

Both products come with a paint kit, and some purchasers have already uploaded their own repaints; it’s possible then, but not guaranteed, that FSD will eventually catch up with SU on the livery count. A good place to find repaints for both products is Sim-Outhouse.com, which specializes in military aircraft and also hosts an active forum.

FSD can launch rockets SU has wheel chocks, oil pan

Both products also include a full range of animations. Pilots move, fuel tanks can be removed (you don’t see them actually fall), machine guns fire (with sound effects), side windows roll down, an access ladder folds down behind the canopy, and the engine nacelles open for the ground crew to rearm the guns.

On the SU model, the wheels are chocked and pitot tubes are covered when you park; if you want, there’s also an oil pan for maintenance. On the FSD model, bombs can be dropped and rockets can be launched from under the wing; you can hear the rockets from the virtual cockpit and see them race ahead of you, but they don’t blow anything up. Both products have red/green/amber recognition lights on the fuselage belly, but only the FSD version can turn them on individually.

Virtual Cockpit

The SU product comes with a 2D cockpit; the FSD product doesn’t. If this matters to you then your choice is easy: SkyUnlimited is your only option. FSD is assuming -- and I think they’re right -- that most of us fly exclusively from the virtual cockpit (VC). And here the choices are more difficult.

Both products have 3D gauges. To my mind, this is the dealmaker. I wouldn’t have said it a year ago, but I think we are at the point in payware development where the best models -- I’m speaking here of small aircraft that don’t have glass cockpits -- all have 3D gauges. Of course, as soon as I say that, good products that don’t have 3D gauges leap to mind -- and happy customers jump to their defense.

I’m not proposing a rule here, just making an observation. 3D gauges are harder to build than 2D gauges, but they look better, enhance frame rates, and move more smoothly. When I think about my favorite planes from the last two years, they all have 3D gauges. And so do these products from FSD and SkyUnlimited.

FlightSim Developers



Several of the plane’s important switches are hidden behind the yoke, so both products allow you to make the yoke disappear. Both cockpits also feature reflector gun sights, but these are for show: neither of them is gyro-corrected like the real thing. (To see how the real thing works, watch this eight-second video: http://www.youtube.com/watch?v=Blem3FlkaMc.) As A2A, Classics Hangar, and other developers have shown, this can be simulated. But in the absence of shootable targets, it’s fair to wonder: is it important?

FSD cockpit lighting SU cockpit lighting

So much for what the two cockpits have in common. How do they differ? Generally speaking, the FSD cockpits have more detailed 3D modeling and shinier textures. The SU cockpits are modeled with less precision; and the textures are matte green instead of glossy black. The SU panel also has labels stenciled on its surface, with various speed placards, a compass card, and a compressibility chart pasted on the yoke. The FSD gauges have better glass reflections, but the SU gauges seem to be rounder. The SU altimeter also lacks a ten-thousands needle, which the FSD altimeter has, and which this plane actually needs.


What I like best, though, about the SU cockpit is that the flaps lever moves when you press the flaps button on your controller. In the FSD cockpit, the flaps will work -- and you will hear them extend and retract -- but if you don’t drag the lever with your mouse, it won’t move to indicate the new position. This kind of behavior isn’t unprecedented (cf. the prop lever in the Digital Aviation Do-27), but it’s hard not to prefer the more straightforward system of the SU product, in which the flaps lever is synchronized with the yoke or joystick.

Modern avionics (FSD)

That being said, objects in the FSD cockpit are modeled more smoothly. And some pilots will prefer the cleaner look of the FSD instrument panel. Another point in FSD’s favor is the option to fly with modern avionics -- which amounts to a second instrument panel. If you prefer vintage gauges, this won’t matter: both products have them. But if you want to fly long distances (and you don’t want to navigate by dead reckoning) then the modern suite of instruments is useful, powerful -- there’s a reason they each come with their own manuals -- and well polished.


The sounds for both products were created by the same person, David C. Copley, who recorded them from Glacier Girl, a P-38 that was recovered in 1992 and restored to flying condition, fifty years after she made an emergency landing on the Greenland icepack.

With a couple of exceptions, the sound files for the two products are either identical or indistinguishable. For stalls, the SU product has a clicker sound; the FSD product has a wind rumble. The FSD product also has a motor sound for the dive flaps and a deeper, more layered wind sound.

Flight Model

Unfortunately, I am not a pilot of anything, much less a vintage, high-octane, high-altitude fighter-bomber like the P-38. What I have to say, therefore, about the flight model of the two products comes from reading about the real plane, not flying it.

But first, a few words about pedigree. The FSD flight model was produced by the same David Copley who did the sounds; in 2000, Copley produced a freeware model of the P-38, and the flight model in this product has evolved from that. SU’s flight model, by Jerry Beckwith, also goes back a few years, to FS2004.

SU climbing FSD descending

Compared with other fighters from the same period, the P-38 was sluggish in the roll access; this is accurately reflected in both products.

What made the Lightning infamous, however, was the loss of control that pilots experienced in a high-speed dive. It was called compressibility and it began with buffeting: the elevator would seize up, and the dive would steepen. To pull out, the pilot could use elevator trim -- that worked sometimes. Or he could wait until the plane descended into thicker air and his elevator started to respond again -- but by that time he was already hurtling down toward earth at terrific speed.

One response was pilot training: don’t let your speed build up in a dive, especially from high altitude. The other, technical response was to add dive flaps: spoilers that opened under the wing and interrupted the airflow.

How well is this modeled in the two products we are reviewing? Both products include the L variation, with the dive flaps, and both products simulate control failure in a steep dive (but minus the violent buffeting). In the FSD planes, you can always save yourself with elevator trim. Not so in the SU versions: trim has a more subtle effect there and, once established in a steep dive, you are probably cooked.

Speaking of getting cooked, there are also minor differences in engine handling. The FSD engines will blow out if you push them too long at full power. The SU engines are, you could say, less realistic or more durable: you can run them at full throttle forever.

Both models are turbocharged (just as the real birds were) so that you don’t start to lose manifold pressure until about FL250. The difference is fuel-to-air ratio: the real Lightnings adjusted this automatically, and so do the FSD models. With the SU models, you have to adjust the fuel mixture yourself, or you will lose power as you climb. This isn’t a big deal, and to fix it you just need to change one line in aircraft.cfg: fuel_air_auto_mixture=1 instead of 0.

Another difference -- one that favors the SU model -- is drop tank behavior. When you drop tanks in the SU Lightning, the plane suddenly gets lighter and climbs -- which is what you’d expect. When you do the same thing in the FSD Lightning, the nose pitches down slightly. That doesn’t make sense to me, but my degree is in literature not physics.


The SU product, because it is less detailed, has better frame rates. The difference is noticeable, but on my rig (described above) both products were able to maintain my frame lock speed of 20 fps except in the most demanding situations (heavy weather, dense autogen).

FSD texture lag

The FSD product is more demanding. For one thing, it uses larger texture sheets: they look sharp, but they’re more work for your computer to manipulate; and it’s possible to get bogged down if you don’t have a robust video card and lots of RAM. For customers in that situation, FSD provides a set of reduced-size textures; they aren’t as sharp, but they use less memory.

When I first started testing these products, I was running the 32-bit version of Windows XP. With the FSD product, there was a noticeable lag between switching to a new view and all of the textures loading; this is not unusual on high-end models, but there was no such lag with the SU product. A week or two later, I installed the 64-bit version of Windows 7; the sim was smoother in general, and the texture lag was reduced to a point where I no longer noticed it.


I’m not one of those people who say, “It’s all good.” When you hear that, it’s usually because something is bad. In grown-up land, all products are not created equal. But in this case, both products are good.

If you like it shiny, or you need modern avionics, FSD is your obvious choice. If you want to save a few bucks, or you’re worried about frames, the safe choice is SkyUnlimited. FSD has more detail, SU has more repaints. Both products have the same, rich sounds; and both products feature 3D gauges in the virtual cockpit. It’s refreshing to have a real choice.


This review was originally published in December 2009. Since then, I have learned a couple of new things about the P-38 and its in-game avatars. According to modeler Kevin Miller, "No P-38 ever flew combat with a 'Gyro Stabilized' (K-14) gunsight. There was a prototype with one mounted, but the bulk of them were diverted to P-51s and some P-47s. The P-38 used a standard optical gunsight (N-9)."

Chuck Jodry, who worked on the FSD project, also clarified some points about the FSD's feature set. There is a way to watch your bombs and tanks drop away, even in spot plane view, by using a 2D popup. There are sounds for the machine guns, as well as the bombs; and if you're flying online, anyone within a 1200-foot radius will hear your guns and see your tracer rounds. "It isn’t possible in an FSHost session to be destroyed by these rounds, but it does add something of a thrill to a game to see these whizzing by."



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Lockheed P-38 Lightning

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