Some add-ons are more anticipated than others, and some are sleepers. This one may take a few of you by surprise. If you tend to lean towards the light twin general aviation fleet then September 2011 was like an early Christmas for many flight simmers. That is when Carenado released their Cessna 337H Skymaster for FSX.
It did not come as a surprise as Carenado had been posting progress photos on their website of the project in the works. What did come as a surprise to many is just how good this one is.
Many of the AVSIM reviewers seem to be stunned by the increased quality of recent FSX add-ons and also the quantity. It is amazing how quickly some of our developers, including Carenado, can turn out these high quality aircraft.
This one in particular seems to be one of those milestone type accomplishments. This is my personal opinion only, but the Carenado Cessna 337H Skymaster has all the necessary qualities to be in the top 10 of all FSX aircraft. After a year or two of flying this one, maybe someone will post a user poll and we can see if I am correct. Right or wrong, it will be mentioned quite often when someone starts a post asking for suggestions for a light twin.
This is not because it is the only twin engine push – pull configuration that looks and flies like a high performance single or that Carenado took longer or paid more attention to this one than some of the others in their stable. It is also not because any new, special or innovative design techniques were implemented, although there are a few new ones on the Skymaster.
My suggestion is simple, the stars were aligned, the timing was perfect, the choice of aircraft was dead on, the designer made all the correct decisions, the flight model was tuned properly and the result will most likely be a true classic for FSX. The bottom line is that it looks good, feels good, sounds good, has a roomy cabin, it’s easy to fly and the view from the cockpit is outstanding.
This one is part of Carenado’s new HD series and comes with 2048 x2048 textures (4X standard), 3D gauges, digital stereo sounds, and the best quality animated pilots that I have seen in any simulation. Most of us didn’t even notice the new banner that comes with this one – ‘Ultimate Aircraft Technology Development”, a new Lexus like group at Carenado.
There are no Heidi type passengers or goofy looking pilots flying the Skymaster, these guys appear to be genuine simulator pilots. Good job Fernando.
Carenado has been listening to the user community and has for some time now been making their add-ons more customizable by us sim pilots. In addition to the expected on or off 3D knobs, window transparency selection, Reality XP integration, and all the static elements like chocks, they have now introduced a user option for instrument reflections, on or off.
Two new features are ‘Fresnel shader maps’ allowing more realistic reflections and lighting; and a new night lighting technology whereas more light produces different types of shadows. This effect produces a better immersion in the VC at night, like the real aircraft. The avionics and instruments that have light or emit light can be seen when all lights are turned off.
As most of you know, Carenado is one of the quality add-on developers for general aviation aircraft for FS9, FSX and more recently for X Plane. Based in Chile, they have a very large following by sim pilots and many just automatically purchase whatever Carenado produces on the day of release.
This is based on their track record of providing near real world type add-ons that are usually tested by real world pilots, and with options such as floats, amphibians, skis, bush, etc. They have a mix of singles, twins, tail draggers (some of the best available), tricycle gear, low wing, high wing, simple panels, complex panels, you name it they have one for you.
The Carenado AVSIM Forums provide the unofficial support for their fleet. It is not uncommon to see users posting useful add-ons or tweaks for these aircraft. Case in point, one of our senior reviewers, Bert Pieke, contributed a very ingenious XML to add a remote Increase/Decrease scroll button feature to the Autopilot for the C337H Skymaster. This allows us to tweak our altitude without looking and reaching down near our ankles. This is one of those nice aspects of modifying simulation panels vs. real world panels, and is really handy on those hairy, bad weather approaches to minimums.
Carenado follows the forums on a regular basis and is usually quick to provide any necessary patches and to make available Service Pack (SP) type updates when appropriate. This one had a SP1 about a week after release. Mostly minor, but irritating issues were fixed. Independent brakes refined, thermometer error correction, low RPM sound adjusted, GPS clickable area extended kind of stuff.
Tell me about the Cessna 337 Skymaster
The 337 Skymaster's high wing front/rear in-line engine layout started out as the fixed-gear Model 336 in 1964, powered by Continental IO-360-A 195 HP engines. A fixed gear, in-line twin didn’t impress too many folks and Cessna sold only 195 the first year of production; 86 remain on the FAA's registry today. A year later, retractable gear was added, the engines upgraded to Continental IO-360-Cs pumping out 210 HP, a sleek dorsal air scoop to help cool the rear engine, variable cowl flaps and repositioned forward engine and cowl for improved visibility were added, resulting in the 337 Skymaster.
The quick method of adding retractable gear was to borrow the complex and troublesome hydraulic landing gear system from the Cessna 210. In 1973, this retraction system was upgraded to a simpler and more reliable electro-hydraulic system. While less complex and easier to maintain, the system still isn't as robust as some of the competitors. It looks quirky and appears to drop by gravity, hesitate at the low point, then continues to lock into place. On climb out it just looks like a Cessna single engine retractable, with all the weird looking motions, twists and turns. Once securely in the dedicated wheel well, the 337 looks like the sleek, efficient aircraft that it is. It is certified to fly up to max cruise speed with the gear extended. This is very uncommon.
Cessna built slightly more than 500 modified Skymasters for the U.S. Air Force, which saw action in Vietnam as O-2A Forward Air Controllers. The military variant lost the forward spinner, gained a bunch of additional rivets for structural hardening, wing hard points and extra windows for better downward visibility. The fixed hard points enabled the O-2A to deliver rockets, flares, and other ordnance for self defense and to designate targets for air strikes.
31 civilian models were converted to the O-2B configuration for the military to use in psychological warfare. These were standard civilian models dressed up with a military paint job and modified for dropping leaflets and blasting messages with a PA system.
The 337'S gross weight crept up during its years in production. Early models started at around 4200 pounds; late ones weighed 4630 pounds, with a max landing weight 4400 pounds. The Skymaster doesn't perform that much better than a Cessna 210, but has a higher payload and the 2nd engine in the back. It has two of everything to maintain and replace, increasing operating and ownership costs. But, of course, it has two engines and that second engine just might save your life one day. Owners usually agree the extra cost is well worth it within minutes of an engine failure at a critical time.
Our simulator model is based on an H model that was built in 1975. In my digging around for specific performance information, I came to the conclusion that you could use the ‘G’ model performance data and be 100% accurate for the simulator model. There are only a few minor differences - the one that is most noticeable is the addition of the large baggage door. See Image.
OK, so what do I get in the download? One 103 MB .exe file.
The Skymaster is listed at $34.95 USD on the Carenado website. Like most Carenado products, it can be purchased at other websites including the Avsim Store. Many forms of payment are available and upon checkout, you will be given access to the executable file to download or sometimes you may receive an email with the order confirmation that will include a download link and serial number.
The ZIP file name is a little cryptic and does not have any correlation to the C337 that I can see. The exe file is 103MB, the installation is simple and quick, and requires only a username or email address and password as well as the path to your FSX directory. If using win7, ensure you have Admin privileges.
The installation will place the necessary aircraft files in the FSX/Simobjects/Airplanes folder including five repaints, and a new Carenado/C337 Skymaster folder in the main FSX directory folder which contains 6 PDF files.
This one does not come with an Instructions Manual, Owner’s Manual or a Pilot’s Operating Handbook (POH) as many other high end add-ons do. It does have some parts and pieces of a Cessna C337H 30 year old Pilot’s Operating Handbook lookalike. Here is what you will find for documentation in your FSX/Carenado/C337Skymaster folder:
Normal and Emergency Procedures – Performance Tables 33 pages
The first item is the meat of the documentation and covers the normal & emergency checklists; engine out procedures, forced landings, fires, landing gear malfunction, electrical failures, icing, and cruise performance charts. These cruise performance charts are for 2500, 5000, 7500, 10,000, 12,500 and 15,000 ft. The keyboard shortcut Shift + 2 will bring up this document when FSX is running.
Here is a typical page from the Normal Procedures and the cruise chart for 10,000 feet. There seems to be a mix of using knots and statue miles and miles per hour throughout the documentation. The charts and tables that I make will have both so you can choose your flavor.
Patrick van der Nat, aka Soya, has provided practically all original screenshots for this review. Make sure you click on the images for some breathtaking full sized screenshots. Here are the standard liveries installed. Notice the all white paint kit texture.
Cessna’s decision to build an in-line twin engine aircraft was centered around the ease of use and simplicity. I’m not totally convinced this plane is easy for a beginner to fly and it is certainly not simple, although it is fun. Oh, it is easy enough for a pilot familiar with say a Cessna 182RG or 210 to transition to the 337H or a Mooney or retractable single engine Piper for that matter. These guys and girls get lulled into thinking it is almost the same plane with an extra engine in the back for emergencies. It is a little more complicated than that.
That rear engine is totally out of sight any time the pilot is in the cockpit and it is quite easy to not immediately notice, should it decide to quit running. One must be alert at all times to check that it is indeed “pushing” its weight. The best way I found is to constantly check the fuel flow gauges. The RPM gauge is not accurate enough as it takes some amount of time for the rpm to make a significant drop, nor is the manifold pressure gauge. You can get false readings assuming you are in the air flying when the rear engine stops. But if it is not running, it will never have a constant fuel flow and the cylinder head temperature should be dropping.
This is in the simulation we are talking here, in the real world if you are airborne and loose the rear engine you will notice an immediate drop in airspeed of about 20 knots or so and it will feel like you just picked up an anchor as you will feel your shoulder harness tighten up.
In early days it was not uncommon to see aborted takeoffs of the C337 simply because the pilot failed to notice the rear engine had conked out somewhere along the taxi stage and the pilot also evidently failed to do a proper engine run-up and mag check prior to takeoff. Posted placards state, at the insistence of the FAA that the normal operation should be to lead with only the rear engine for takeoff then follow with the forward engine. This is to ensure the rear engine is actually running at normal power for takeoff. Rotation and climb out would not be a good time to discover your twin is actually a single. Single engine takeoffs are prohibited.
This is one of the reasons you see the C337 taxi with the tractor engine completely shut down. One , you don’t need two engines to taxi, two, you save on fuel and wear and tear on parts, and 3, you probably won’t attempt a takeoff if the prop you are looking at is not turning.
Ever wonder which engine is number 1 and which is number 2 in a center-line-thrust twin? When I was flying these things way back when, your pilots license rating actually stated ‘multi-engine, centerline thrust only’ if you used a C337 for your multi check ride. This was because the asymmetrical thrust when losing an engine on takeoff in a typical engine on the wing twin is so different than that of the in-line twin. The old adage of ‘dead engine, dead rudder’ does not apply to the in-line thrust versions. When you lose one of these, it is not a real big deal. Just clean it up and decide to continue with your flight, go back home or go looking for the $100 hamburger and a mechanic.
Of course, all those folks that own a Skymaster really don’t have to worry about that as long as they continue to fly their C337 and not attempt to try out a C-340 or other conventional twin with the engines on the wing.
I got my real world multi in a Piper Aztec. This was one of the few twins that would actually continue to climb should you lose an engine on takeoff. Most of my thousand or so hours in twins is flying an Aero Commander 560A. About the only thing it has in common with the Skymaster is it has a high wing and two engines. Even the door is on the opposite side of the plane.
The Pusher engine in the rear has a little better performance than the upfront Tractor engine. This is the result of a slightly different setting for the rear propeller pitch. I think it is on the order of less than 100 FPM more efficient. The specs state a 300 FPM climb on one engine, which is very respectable. There is a section in the pdf file on page 13 that outlines a fun practice drill for an engine out at altitude procedure. You don’t actually kill an engine, just set the proper rpm and manifold pressure to simulate an engine failure. I guess this would be a simulated simulation. Duh.
Many people think the C337 is the only centerline thrust twin around but Burt Rutan’s Defiant (RAF-40) is another one with similar and better performance with much smaller engines. It only comes as a homebuilt kit and has the iconic Rutan canard wing up front. No FSX version yet.
What do the numbers look like? Good numbers.
The C337H is not going to set any speed records but it does have a better than average time in the sky. The Reference Speeds pdf included in the documentation has the speeds in both MPH and Knots. This is due to the date of manufacture, when we were in the transition period from MPH to Knots. I have always liked MPH for cruise speeds because it just sounds like I am going faster.
Here are the specs and speeds for the Cessna 337H Skymaster from the pdf documentation. These are the speeds you will see when you select Kneeboard/Reference from the FSX top menu.
What PC specs do I need to run this add on? Just a basic FSX machine.
• Flight Simulator X (SP1 & SP2 required)
Here are the C337H features as listed on the Carenado website.
• Two models (one pilot / two pilots)
Note: May be realistic behavior and realistic weight and balance. This is after all still a simulation; nothing is really real, except me.
Some of the features that I find noteworthy are the
Note: Most users do not know the CDI button near the left bottom is the NAV/GPS switch on the GNS530.
Why I like the Carenado Cessna 337H Skymaster as a FSX add on.
While talking about the two rear seats, they should actually be called ‘child seats’, not because of size but because they are the same size as the two middle seats, it is just that you have to choose people over fuel if you wanted to stay within the Max allowable gross weight and fly a reasonable distance. Same as almost every other 6 place plane – it is really a terrific 4 place plane with two extra seats.
If I had to pick what I like most about flying the Carenado Skymaster in FSX it would be something to do with the spacious cabin, extraordinary visibility from the pilot’s seat in all directions, including down and the VC panel textures along with the 3D gauges and new lighting. Plus the realistic engine sounds and that big GPS face and the Collins radio large dial readouts and as stated earlier, the 9 button lighted mode selector. I also like the external textures and suspect there will be hundreds of freeware repaints available for download.
Safety-wise, the big issue is a takeoff with the rear engine flamed out, as there is no V1 engine-out, continue-takeoff speed on the 337. Just stop on the runway. To avoid wrecking your plane in this scenario, it is simple: Start your takeoff roll by bringing up the rear engine to 25 inches, making sure it responds properly, and then bring up the front to match. When satisfied, push the throttles to the firewall. You will need dual throttles in your sim setup. Some of us have them, some don’t. It really doesn’t matter a whole lot in FSX if you smash into the interstate traffic from a muffed takeoff. Just reboot, get a cup of coffee and do it right the next time or the next.
But, I was just thinking – this would be a great add-on feature by our resident XML code writer. Imagine a little pop-up slider for the two throttles, where we use the mouse scroll wheel to smoothly advance the Pusher engine up to the 25 IN MP then come in with the right throttle to match it then reach down and use our hardware throttle to push to the firewall. Now wouldn’t that be neat, Bert?
Because you are reading about a fairly high performance twin engine aircraft, I am going to assume that you already know the parts and pieces of an airplane, why they are there, and what they do. A twin is usually not the first aircraft for a real world pilot or a simulator pilot. But just in case you would like to know a lot more detail than what comes with your download, you can search the web and find a 31 page pdf that describes a ‘D’ model that is about 95% the same as this one. Google should point you to the proper location if you use these key words - ‘Cessna Skymaster 337 Manual checklists description’ This will also lead you to a 6 page Checklist that is based on a ‘D’ also about 95% correct for this model.
You can make the necessary corrections and have your own specific versions. The speeds and altitude data is not correct for the H model because one model is older and the other is a Turbo.
If you haven’t flown a lot of Cessna high wing airplanes you will be in for a weird sound when you activate the wing flaps. These are electric and use 1/3 increments. The sounds are very distinctive and loud. I think the Cessna flap designer wanted you to know the flaps were operating without visually checking. That is not a developer issue.
For those that will be transitioning to a retractable gear airplane for the first time or have just been flying in the bush for the last few years, you need to remember to let the gear down before landing. Those of us that use checklists will find that is a prominent item and a quite important one. Because it moves, is big and complicated, and gets hammered from time to time, the landing gear is prone to failure.
There is a large section in the documentation on how to deal with this issue and it is worth spending some time getting familiar with manual operation. FSX has some limitations on what can be modeled in this area, but it is all for naught as Carenado chose not to model any of the manual gear operation. Drat, double drat.
Remember to tap the brakes when you have positive rate of climb to stop the wheel from spinning. That has always been a good reminder for me to initiate the gear up sequence. I always taught my advanced students to delay the gear up sequence in the Cessna 210 due to the excessive drag caused by the wheel well doors hanging out. Raise that gear too early and your prop will be eating concrete before you know it. You have a net increase in drag rather than a net increase in lift when those huge doors are opened. This C337H is more powerful and the effect is not near as great but it is still there and it is modeled in this Carenado version.
Cowl flaps for engine cooling may be new to some of you so make sure you read up on the when, why and how to save excessive wear and tear on the engines. These are front and rear. The cylinder head temperature gauge should be in your cockpit scan. The switches are smarter than the obvious on or off. You can have them partially open by selected Open then a second later stop the motion.
Further, I have assumed you know how to fly, so I am not going to spend time on the basics but I want to know the important speeds of a new airplane and I have always made my own notes and usually printed out a little chart to have handy. I grew up as a flight instructor and it seemed that every time I reached for the POH it was not there. The students tend to ‘borrow’ the manuals and forget to put them back in the airplane.
Looking around any airplane and reading the placards is always a good idea. This is something useful to do when you are 8th in line for takeoff or some other dead time. You will find a checklist permanently mounted behind the pilot’s visor.
You will find as lot more performance data in this review than comes with the download from Carenado. This is result of many hours of research and cross checking a lot of conflicting data. You may want to screen capture a few of the charts for your notes.
Leaning the fuel/air mixture.
This is worth its own paragraph. Leaning the fuel/air mixture in this simulation is required if you wish to obtain the airspeeds and cruise performance shown in the documentation. Any of the higher altitudes require substantial reduction from the normal rich mixture settings used for standard takeoffs and initial climbs.
Fortunately, the exhaust gas temperature gauge (EGT) is almost self explanatory and has a good location in the panel. It is almost directly in front of the pilot so it should catch your attention from time to time. This is the most accurate method of measuring the leaning process and it is close to the airspeed indicator which is one of the gauges that shows the results.
The two mixture levers will appear to be pulled back almost to the full lean or cutoff position as shown in the nearby image. Continue tweaking and monitoring your settings for best performance.
EGT explanation - Exhaust gas temperature varies with fuel-to-air ratio, power, and RPM. However, the difference between the peak EGT and the EGT at the cruise mixture setting is essentially constant in the simulator and this provides a useful leaning aid.
The manual states… to adjust the mixture, using the indicator, lean to establish the peak EGT as a reference point and then enrich the mixture by a desired increment based on the table shown. Operation on the lean side of peak is not authorized. You will need to recheck your mixture settings often.
Fuel Tank Switches (forward overhead)
This can’t get any simpler. Put the pointy end on Takeoff for take-offs and switch to the Yellow side for Cruise (Level Flight Only). The only other position is OFF and it is Red and the engines will not run in that position.
The Front engine is on the bottom and labeled FRONT. The other one is the Pusher engine in the rear.
How about some nice screenshots of this bird on takeoff and climb out?
This web link has almost unlimited information that explains the nitty gritty of the systems and specific instruments or equipment for the Skymaster. I just glanced over an 11 page explanation of the autopilot. (links below) Most other components have the same level of detail.
Here are some comments from a real world owner of a 337 Skymaster.
While leaving the gear down produces a climb penalty of a bit over 100 FPM, raising it carries a temporary 240 FPM hit. This is because of Cessna's complicated gear door arrangement which adds a lot of drag while the gear is in transit. In an after-takeoff engine-out situation, it may be better to leave down the gear, just as it is recommended in some singles to leave it down until obstacles are cleared. In normal flight, the Skymaster has typical Cessna handling: heavy in pitch, reasonably responsive ailerons. Pilots praise its IFR stability.
The Skymaster's visibility is excellent - about as good as it gets in any light airplane, single or twin. The view down is unlimited, of course, and the wing's leading edge is back far enough that it doesn't block upward vision either, as with most Cessna singles. Good visibility is not only a safety feature; it adds to the feeling of roominess in the cockpit.
Speed-wise, it's really not that fast and the book numbers exaggerate, but fast enough to do mid-continent to the coast in a day. Contrary to popular myth, the rear engine does not overheat. It's really phenomenal in the landing pattern, and has superb crosswind handling. Centerline thrust in this twin is a beautiful reality.
The Skymaster is a complex airplane and does require a checkout, along with some attention to fuel management, systems and synchronizing the engines, but it is a great plane for transitioning to twins and provides lots of safety when compared to a single.
One last comment: The standard line is that there is very little indication of a rear engine failure. Other than the sputtering sound, the sudden and noticeable pressure on the restraining harness against your chest and the rapid loss of about 15 to 20 knots in airspeed, there aren't many clues. If someone cannot feel this and see the drop in fuel flow and cylinder head temperatures, they probably should not be flying anything.
So everything is perfect in this add-on?
FSX add-ons are never perfect. Sooner or later someone will find some wart or blister. Most of what I have read at in the forums are simple mistakes junior pilots are making but there is a short list that Carenado is compiling for the next service Pack. Everything I found is very minor and I could live with them without a fix. I think Carenado must put out each release with a misspelled word on the panel or window just to see if we are paying attention. I noticed the Landing Light is labeled LOG rather than LDG and the tooltips are mixed up on the Aux Fuel Pump switch, and some external antenna shadows are dotted lines but let me ask you, What do you expect for $35.00? This one is so good that I might just decide to live with it just as it is.
I did find the aircraft.cfg aircraft description is out in left field someplace, not that it affects anything, and I think I might be the first one to notice it in two months. The next patch will update the aircraft.cfg file and correct it but now that you know about it, you can backup your original and correct it yourself if it bothers you.
Until someone comes along with different numbers I am using these as the performance specifications for the aircraft.cfg file. These are the specifications that should show up when you click ‘details’ on the FSX selection screen.
I think we may be approaching the time when someone adds passengers to the empty seats. I know Just Flight has them but they look like they are made of paper and wax. I would like to see a couple of sharp looking ladies in the 3rd and 4th seat to go with the great looking front seat drivers. When I lived in Europe and two couples traveled, it was considered 3rd class if the girls were in the back, 1st class if the couples were mixed. The load manager should be able to handle it. How about it, Fernando?
This is such a short review for me that I hate to repeat what I have just said. I obviously think this is the best add-on to come out of the Carenado shop to date and I have many of their most popular ones for comparison. I don’t see any downside for this add-on. It looks good, flies good, has a large roomy cabin, outstanding visibility, a sim pilots dream with flight director, autopilot, advanced GPS, full IFR capability, dual most everything including engines, exceptional new night lighting, HD exterior and interior textures. Marvelous sounds inside and out. Spot on modeling, good looking pilots and frame rate friendly.
The only thing left for me to say is it is a slam dunk for recommendation for the coveted AVSIM gold star.
Depending on your age or inclinations, you could ask Santa to make this one of your under the tree presents, or ask your spouse, kids, grandkids, mom or dad to make it a stocking stuffer, or you could just go to the Carenado site or the Avsim Store and purchase it and be flying in an hour or so. It really is that good.
The military variant, the O-2A with the 2 extra windows near the knees on the starboard side and the four hard points on the wings for the flares, rockets, machine guns, etc. with an optional forward spinner (for the O-2B) and a few of the period paint textures would make a great follow-on package. This can replace the standard floats, amphib, skis, tundra pack.
There must be hundreds and hundreds of Southeast Asia veterans and sons and daughters of those veterans that would jump on this with both feet. It doesn’t even have to fire the flares and rockets, just static hangers. Of course, it would be nice to be able to change out the stores from mission to mission. Hello Captain Sim Weapon.
Enough said. Meanwhile, our freeware repaint artists are already at work. Check out this beauty by Russel R. Smith. Available at the AVSIM library of course.
Real world O-2A with rocker launchers.
A collection of available freeware repaints for the military variant lookalike and a representative of Reims Aviation. All freeware found in the Avsim library. Thanks guys and girls.
Is that a brown pelican? No, it’s a CIRPAS pelican. Only one of two in existence. A very rare bird, indeed.
This is a highly modified H model. Tractor engine totally removed, pusher engine replaced with an IO-550 with 300hp. Passenger seats taken out to make room for monitoring equipment. It was designed for long endurance, low altitude air sampling but has been configured to operate as a UAV surrogate for the U.S. Navy.
Pelican is now intended to function as a manned or unmanned sensor platform embodying the flight control package developed of the Predator UAV.
Used by NASA and the NPS. Go Navy.
Page 4, O-2A side windows, photo taken by Oliver Lacombe, no copyright, 2010 airventure.
Page 10, Screenshot showing Reality XP installation, by Bert Pieke, used with permission.
All other screenshots by Author
Tell A Friend About this Review!
All Rights Reserved