It was the Swiss who first made the Lyomcong/Jungmann conversion but their expertise was not available outside of Switzerland. When contacted (through Arnold Wagner) Pilatus declined to make their conversion available to amateur operators, so in the USA Frank Price, Mira Slovak and Shelby Krister all worked on producing conversions. Looking through the documents provided by Steve Hawley it can be seen that there were some very prominent aviators involded: Bevo Howard, Bill Barber, Henry Haigh, Bruce Kemper and Marion Cole all played a role.
Why add a Lycoming engine and cowl?There are two obvious reasons: Performance and reliability. Converting an aircraft designed around an in-line engine to a horizontally opposed engine changes its appearance and to a small extent its flight characteristics. These are often small prices to pay for being able to actually fly the thing whenever you want, as much as you want at the touch of a button (or key).
When Marion Cole converted his Czech C-104 Jungmann from its original Walter Minor 4-III engine (100 HP) to a Lycoming IO-360 and a constant speed prop, it was to gain enough performance to be (almost) competitive at the World Aerobatic Championships.
Marion Cole's N913CB - Before and after
For most people, however, I suspect the conversion is made to benefit from the simple operation, minimal maintenance requirements, reliability and familiarity of a Lycoming engine. This is particularly true in the USA where every airport has a mechanic who was brought up working on Lycomings, and who has shelves full of parts in the back of the hangar. If you learned to fly here the chances are you learned in an aircraft with an opposed engine. (A baby duck is said to assume that whatever it first sees upon hatching from the egg is its mother, and will follow that object around for ever more. It's the same for baby pilots I think :)
The engines originally fitted to these aircraft do have some short-comings of course. The Hirth is a beautiful, almost jewel like engine, but parts are very difficult to find and an overhauls absurdly expensive. The Walter Minor is rather shaky, requires constant tinkering with the valve mechanism and is also hard to find parts for, while the ENMA Tigre is heavy, the 150 HP version is also shaky, and the safe operation of the engine requires a considerable investment in maintenance. Fail to maintain it as its designers (and Larry Ernewein) prescribe and it may well let you down.
The Jungmann was designed for an in-line, inverted engine with four cylinders Being inverted, the engine thrust line was quite high. What in 1930s USA was called a "hi-drive" engine. Look at this picture of a Joe Krybus engine mount (which preserves the original thrust line) installed on a CASA fuselage and you can readily see that even the bottom engine mounts are higher than the top fuselage attach points on the firewall.
Some of the earliest conversions overcame this problem by ignoring it and simply bolting a conventional Piper PA-18 style engine mount to the four firewall attach points. This radically changed the appearance of the aircraft and I assume, its handling too.
Placing the oil cooler on top of the engine did nothing for the aesthetics either, in my opinion. This arrangement is sometimes referred to as the "Three Amigos" cowling. Mira Slovak's Jungmann initially used this same conversion when it appeared in the otherwise dreadful movie "The Three Amigos". https://youtu.be/Q-5huk507YM?t=1h27m1s (The movie titles credit Jimmy Fraklin with the flying, but Mira told me it was really him. Jimmy was the only one with an Equity card, so he got the credit.)
This is another early Jungmann/Lycoming mount. The thrust line is higher this time, but still well below the original.
To get the engine thrust line in the right place requires an offset mount, and that requires some engineering. People have gone about that in different ways. Joe Krybus and Mike Meloche use a mount with additional bracing that connects the upper engine mounts to the fuselage structure ahead of the front cockpit (the rear cabane mounts). Woody Menear, Pilatus, APM and others have added the required bracing without using additional longitudinal tubes. Since an engineering analysis was performed for all of these different systems, and since none have been known to fail in service, I would say it is a matter of personal preference. Choose the system (matching mount and cowl) that you prefer and enjoy it!
How the Swiss "APM" engine mount accommodates the high thrust line
The rest of this article will address the history and the details of various Lycoming engine conversion systems.
Joe Krybus/Earl HickmanThe conversion engineered by Joe Krybus, optionally with the cowl designed by Earl Hickman) is one of the most popular conversions.
Pat Quinn operates from the same airport as Joe (Santa Paula, California) so is familiar with its history. Like all of us, Pat has his own tastes and opinions:
I asked Joe Krybus about the Lycoming/cowling conversions here in the USA and it his memory that either Marion Cole or Mira Slovak had the first one. I looked through my albums and found a picture of Mira Slovak’s a Jungmann at the September, 1964 Reno Air Races with the Walter engine and a snapshot of the same Jungmann with the Lycoming conversion in September, 1965 at Santa Paula. So somewhere in the late 64-65 time frame was Mira’s low thrust line conversion done. The mechanic, who was later killed in an unrelated plane crash was Hank Kennedy - as per the 1964 Mira Slovak article.
That cowling was somewhat copied by Hank Galpin on the Jungmann now owned by Jim White in Georgia. Another was copied on the Jungmann owned by Dan Miller in Battleground, Washington (As far as I know, this is the last surviving low thrust line cowling and mount). A very poor looking attempt was done by Perry Scheffler at Santa Paula. It actually looked like a Piper Apache cowl turned upside down. In my humble opinion, it was the ugliest Lycoming cowl ever. That Jungmann was destroyed in a crash by the German owner Uwe Stickler was his name . The remnants, which survive in Canada, come up for sale from time to time. Most recently for $4,000, but it didn't sell.
The Three Amigos Jungmann was another low thrust line Jungmann done by Mira Slovak, if my memory serves me correctly. It later was rebuilt using the Krybus cowling and mount. It was I the white and black color scheme that Mira used. The aircraft is now being enjoyed by John Grinalds on the East coast.
The Marion Cole cowl is what we have always called the “Frank Price Cowl”. A similar looking one is on the Jungmann now owned by Mike Meloche as well as several others, including the new one installed on Jim White’s Jungmann. Perhaps Mike can fill you in on that cowl. (He did - see below) For my taste, that cowl covered the gas tank area and makes the Jungmann look somewhat fat in the front end as opposed to long and graceful like the Krybus and Pitts style mounts. But beauty is in the eye of the beholder. Right?
"Standard" Joe Krybus cowling
Woody Menear in Hershey, Pennsylvania did an early cowling and mount which relied heavily on the then technology of the Pitts. One of the first was for airline executive, Dawson Ransom. This orange and white beauty was on the cover of Sport Aviation and was truly my inspiration to get a Jungmann. My Jungmann had a Woody Menear mount and Pitts style cowl when I bought it. It had been converted by John Bergeson in Michigan. Woody then came out with a fiberglass cowl that looked entirely different. My current cowling borrowed the look if not the style from Woody’s early cowl.
Joe Krybus installed his first cowl and mount on OK-BIG, the Czech Jungmann that he had once owned in Czechoslovakia and then owned by Charlie Knapp, a savings and loan executive. It is now owned by John Hickman in El Cajon and is the beautiful blue Jungmann that the Hickman group restored several years ago. The original Krybus cowling and mount are still installed.
One of the distinguishing features of Joe's system is the use of additional bracing tubes that pass through the fuel tank. These brace the upper engine mounts while still allowing the option of leaving the fuel tank exposed per the original.
Joe has sold 28 cowling and mount kits since his first one in 1983. Three are in Spain. Besides that, he has sold some LOM kits including one in Spain and another in Australia. In addition, he has sold five Lycoming kits for Jungmeisters including the one on my Jungmeister, U-72.
In the time before the Lycoming conversions, Joe Krybus had built a Christen Eagle. His Jungmann cowling tends to look a lot like the Eagle cowl. The Hickman family had Robbie Grove make a similar cowl to the Krybus cowl and installed it on their lovely yellow Jungmann. They then gave the molds to Joe Krybus so that he could supply them to those that wanted them. It is sometimes called the Krybus Two cowl or the Krybus/Hickman cowl.
The "standard" Krybus cowling, perhaps influenced a little by his Christen Eagle?
In England, only two Lycoming conversions are approved by the CAA: the Krybus and the Bitz conversions.
Postscript: The company that produced the fiberglass cowls using Joes molds appears to have gone out of business without warning, and Joe is having trouble recovering those molds. For now at least, Joe is able to supply only a few of the cowl types previously offered. Let's hope that changes soon!
The Mike Meloche systemI have my biases too, but I have always thought that if you were to categorize Jungmann then by far the nicest looking of the "muscle" category would be Mike Meloche's N3G. It really is stunning. Mike's conversion requires that the fuel tank is no longer exposed, but it also allows the added engine bracing tubes to be run over, rather than through the tank. Mike also makes some changes to the firewall.
Clearly I am not alone in my opinion, given the number of people who ask if it is for sale. Not while mike has blood in his veins it isn't :)
Here is the information Mike provided:
A.D. Mclarty designed and built the cowl that was on N1936G. This was Jack Williamson's airplane and finished in 1967 for around $75,000. It was later a partnership with John Downing in the mid 1980's. Jack sold his share to John sometime later and gave the cowl/mount to Frank Price to market. This cowl was put on several airplanes including my dad's N1963S.
When I purchased my plane from Joel Kozak he had purchased a cowl and mount from Frank but the cowl would not accept the injected engine so Joel made a cut out in the front to accept the lower requirements for the fuel servo. After I purchased the plane I remade the cowl to fit better and accept the fuel servo with room to spare as well for a PS5 pressure carb and the Ellison throttle body.
I redesigned the engine mount as well and used the new cowl and mounts on my plane. My mount has been adjusted with offset to compensate from engine torque and has braces across the lower four attach points.
When I started restoring my dad's plane I made a mold off my cowl cowl and made these in carbon fiber and fiberglass for several others as well. The engine mount requires the firewall to be remade from the original as it has a step going aft above the original mounts and then vertical just forward of the fuel tank. This puts the engine further aft by 2 1/2 inches from the Joe Krybus mount. This puts the CG in a more desirable location requiring no ballast in the Spanish or Czech airplane configurations.
This mount has the upper mounts that go on the outside of the fuel tank instead of through the fuel tank as the Krybus mount does (requiring tubes to be welded in the fuel tank.) The upper mounts attach to the rear cabane clusters. The engine baffling has accommodations for the air filter box on the left front side giving the cowl a completely free installation without any attachments or ducts mounted to the cowl. This renders the cowl to be removed in only minutes completely or either top or bottom left attached.
Although not aesthetically pleasing to all it is the most friendly of all cowls to do maintenance on. I have done restorations with both Krybus cowls and Woody Menar cowls and I still favor the Jack Willamson type as it renders the airplane in a more favorable CG location and hands down the easiest to remove.
I have used this cowl on several restorations including Jim White's airplane in my last restoration. We split the cowl and added one inch in width to accommodate the two hundred horse IO-360 helicopter engine. It was made up with carbon fiber and only weighs several pounds. This in conjunction with the engine mount and relocation of the battery has removed 22 lbs of Ballast from Jim's pre-restored plane. I do believe after flying it several hours post restoration it flys completely differently. Jim actually does good landings now! We just thought it was lack of skills as a airline pilot The CG makes a world of difference in the flying quality as well as the thrust location!
Earl Hickman converted his Walter Minor powered Czech N1947H in 1980 to an 180HP Lycoming. He choose the Krybus cowl/mount. When Earl started a new Spanish airplane project in the late 1980's he had a friend of mine design a new cowl that was a two piece design cowl using the original firewall. It was more rounded than the Krybus cowl and was only two pieces instead of seven. It was more aesthetically pleasing (Earl thought) to have a more rounded cowl as it softened the front of the plane and made it a little easier to remove and lighter in weight by several pounds. After maybe eight years Earl gave the mold to Joe Krybus to market as Earl felt bad the cowl had gained some popularity in community and was leaving Joe out.
The cowl uses the same engine mount as Joe's original Lycoming mount and cowl installation.
The Woody Menear system
From Brian Karli
An 11 year old boy slowly opened the hangar door. Alone, he squeezed inside. In front of him was the most beautiful biplane he had ever seen. It was blue and grey and the airport bums told him a guy named Woody owned it. Praying no one would see him, the boy pulled back the cockpit cover and climbed in. One day, he vowed, he would have his own Bucker.
Elwood Menear grew up in the Harrisburg, Pennsylvania area. While attending Penn State University, he built a Pitts Special. He was beginning his airline career flying for Air Jamaica when the Spanish Air Force began selling their fleet of Bucker Jungmanns. Woody, his brother Harry and Larry Krop bought three from a guy in Texas named Marcus Bates.
Woody came up with the idea of using the original Tigre cowl and sticking the cylinders out the side like a J3 Cub. He wanted to retain “the Bucker look”. He also wanted to keep the plane as light as possible. There would be no starter. The dimensions of the original nose bowl would not for one anyway. There would be no electrical system, battery or radio. “A light Bucker flies best” he was heard to say. Again, Woody wanted to keep his Jungmann “Bucker-ish”
The thrust line of his 150 hp Lycoming mirrored that of the Tigre. Woody told me how he did it. “I leveled the fuselage and dropped a plumb line from the ceiling where the Tigre crankshaft had been. The Tigre was removed and the Lycoming put in its place. From there, I just welded everything up”
Woody designed a 4 point mount that was both light weight and strong. Critics said it was too weak. I’m here to tell you that was not true. A Jungmann once had a prop come loose in flight. The engine shook so badly, the lower longeron broke. Woody’s 4 point mount was fine.
In 1981, Woody’s first Jungmann took to the skies. It was 900 lbs empty and flew like a dream. He designed a nice, curved exhaust system, but it kept cracking. A straight pipe system was installed in its place. The troublesome PS-5 carburetor was replaced by an Ellison TBI. He had a scimitar Hendrickson prop and a fully inverted oil system.
That eleven year old kid eventually got his first Bucker ride in this airplane.
Woody’s Jungmann was not alone in the hangar at the Farmers Pride Airport. Two other untouched CASA Jungmanns were also stored there, guarded by that eleven year old boy who begged his parents to borrow $14,000 to buy one. His parents wisely declined his request so he had to be satisfied with sitting in their dirty cockpits.
Enter a man named Dawson Ransome. The founder of Ransome Airlines, Dawson was an imposing man who flew the Hump during WWII. Always wanting a Bucker, he contacted Woody Menear and a deal was made. The eleven year old boy was there when Woody arrived at the airport with a flat bed truck and hauled off one of “his” Jungmanns.
Dawson hired Woody and his new found business Sky Classics Restorations to bring the Jungmann back to life. Dawson was impressed by Woody’s blue and grey Jungmann but wanted the convenience of a starter. He also wanted an electrical system and a radio to commute from his farm in Bucks County to his airline headquarters at the North East Philadelphia Airport. His choice of engine was the 180 Lycoming.
Woody accommodated the heavier engine by moving is mount back 2 ½ inches. He used a Pitts style nose bowl because of the starter. New axles were fabricated with Cleveland brakes. The airplane turned out beautifully and more Bucker customers rushed to Sky Classics.
Another customer was Dick Farina, an attorney from Washington DC. Although Dawson Randome was satisfied with his cowling, Woody was looking for a way to retain the “Bucker-ish look” for his next customer. He liked the lines of the original cowling but realized the value of a starter. There had to be a way to combine both and Woody had an idea. He hired a local fiberglas guy named John Worm and they started shaping foam. What they created was to be known as the Menear cowl. From the side, the cowl retained the profile of the inline engine. Woody added cheeks to enclose the cylinders and left room for a crossover exhaust. But the best part of this new, revolutionary cowling was the hinge at the top. By turning a couple of dzus fasteners, the entire side of the cowl could be opened up like the hood of a car. You could easily access the engine and it made maintenance very convenient.
Sky Classics made several cowls for other Bucker customers. Woody designed and built a clever jig for making his engine mounts. In the center was a shaft. The dynafocal ring could be moved up and down on the shaft depending on which engine you were using. One jig for both the 150 and 180 hp Lycomings.
Woody developed a number of other modifications for the Jungmann including a light weight battery tray and fiberglas gear leg covers.
Eventually, Woody got out of the Bucker business moving on to other projects. There was a Yak phase, and time was spent building an award winning SX300. Plus, Woody was flying for USAir and maintaining his private airstrip in Pennsylvania. In total, Woody restored his blue and grey Jungmann, followed by Dawson Ransom’s plane, a Jungmann for his wife Sharon, Dick Farina’s Jungmann and assisted with several others. His airplanes were eventually sold and now Woody lives quietly in Hummelstown PA where he tinkers with Porsches in his “garage mahal”.
And that eleven year old kid…well he eventually got a Jungmann of his own and still owns it today.
The Swiss playersIn Switzerland the Lycoming conversion is as popular as elsewhere. The history of these conversions is detailed in the book "Fascination Bücker" and is only summarized here.
As the Hirth engines began reaching the end of their useful life the Morand company in La-tour-de-Trême, located in the Gruyere region of Switzerland developed a Lycoming conversion based on the 150HP O-320. The model number being changed to Bü/APM 131-150. This conversion is by far the most commonly seen in Switzerland today and is generally known as the "APM" conversion..
Other people, most notably under the influence of Albert Reusch and F. Dubs went on to produce conversions with 170 and 180 HP engines (as well as modified airfoil sections, changes to the fuselage profile etc.) Model names included the famous Bü131R-170 "Lerche" and the R-180. The "Flug and Fahrzeug", Max Datwyler, and Pilatus companies participated in these conversions.
Swiss Pilot Max Datwyler produced a 180 HP Lycoming conversion known as the R-180
The cowling appears to use a rather conventional Piper style nosebowl. The "Lerche" had a similar looking cowl, but the most well known Swiss conversion is undoubtedly the "APM" conversion which is still produced today.
Thanks to Steve Hawley, we now have this description of the aircraft, as well as a copy of the flight manual.
INTRODUCTIONIn early summer of 1960 it was concluded that the standard Swiss acrobatic airplane, the Bucker Jungmeister, was no longer competitive against modern foreign airplanes.
It was realized that an ideal acrobatic airplane should have minimum rotational momentum for all axes, light power and wing loading plus considerable rate of climb both in normal and inverted flight. Of various designs the famous Focker Dr1 Triplane appears to best fit these criteria. Because of the considerable amount of money involved in the development of such an airplane, it seemed more appropriate and reason-able to equip a Bucker Jungmann with a more powerful engine.
The Aging Hirth EngineWithin a short period of time two crankshafts have broken on the Hirth HM 504 engines belonging to MFGZ owned Bucker Jungmanns. To them this was a sign that this engine had reached the end of its life cycle. In a Jungmann with two people aboard the power is insufficient for acrobatics. This is evident from the altitude loss. The Hirth engine cannot be used with a radio since the ignition system is not easily shielded. It was thus decided to replace the Hirth engine as soon as possible.
Preparation/Investigation 1) Studied A. Ruesch's Bucker R-170. 2) Designed Engine mount and cowling (similar to Super Cub) with a hinged mount. 3) Selected the Lycoming 10-320 fuel injected engine. 4) Oil tank attached to engine mount and in the air flow. 5) Pilatus AG offered to do the redesign.
Obtaining the engineThe IO-320 with fuel injection had been withdrawn from production. In order not to delay the rebuilding it was decided to equip the plane with the 10-360 B1B. This engine has practically the same size and weight. A complication was that the IO-360 is only available with the dynafocal mount and the engine mount had to be changed.
The Construction of the "Bücker Lerche"Pilatus AG made a very competent group of people available for the redesign. The new engine made it necessary to construct a new hinged engine mount. We also had to beef up the forward end of the fuselage, and also modify the fuel tank. Furthermore we had to recover the front end of the fuselage and also to change the cabane struts including it mounts. We also had to add the oil cooler, and oil tank, and an oil separator. The exhaust manifold had to be completely redesigned. Various instruments were added. The rear instrument panel was rebuilt. For the front cockpit a new cover was built and the front windshield was made removable. To start the engine an external power connector was mounted to the fuselage. The oil system was modified. A major part of this work was related to the construction of a pump for the return oil and a ball valve. To start the engine we used a portable battery that can be stored in the baggage compartment. During acro-batics it can thus easily be removed.
After various tests on the ground we began the flight test. In cooperation with the Federal Aviation Authority I put together a detailed test program. In order to perform the high altitude test an oxygen system had to be installed. With a take off weight of 610 Kg it climbed easily to 6700meters. The outside air temperature was -28deg C. The next series of tests dealt with extreme CG locations. To achieve the max rearward c.g. location 15 Kg of lead was attached to the tail end of the fuselage. To achieve the max forward c.g. location the pilot has to use the forward cockpit. Since there are no brake pedals available there it is quite difficult to taxi. To take care of that problem I used another pilot in the rear cockpit during taxiing. In order to evaluate the unusable fuel fuel volume we flew with a certain altitude until the engine quit. The following landing was almost an emergency landing. After landing the remaining fuel was measured.
Albert Rousch's Jungmann was of similar appearance, but had an exhaust system that exited at the sides of the cowling near the front.
And here is the "APM" cowling
The most noticeable features of the APM are the side vents, the accommodation for muffler required by EU noise regulations, and the very simple mounting system.
The four bolts that attach the engine mount to the firewall are simply extended so that they protrude through the cowl:
And here are some very detailed pictures of the APM system from Albert Zeller:
The "Dynafocal" version of the APM engine mount.
APM engine mount. Not obvious in this pictures is the fact that this mount uses all six of the attach points on the firewall. (Four outer mounts and the two smaller inner mounts)
We are going to see the first APM conversion in the USA before too long. The aircraft pictured at the top of this page is Brian Karli's :)
The Bitz CompanyJosef Griener developed a Lycoming conversion system which as noted above, is one of only two conversions approved by the U.K. CAA. It also has full certification in Germany for bot 160 and 180 HP varients . More inofrmation is on the way and will be added here as soon as possible.
Here are a couple of pictures from http://www.bitz-flugzeugbau.de/
Other conversionsIn addition to the conversions discussed above there were of course other "one off" or small volume conversions. Alan Abell provided some information on the "Tradewinds" conversion. I was certainly not aware of this one. The tradewinds company was based in Amariloo, Texas and was run by newspaper man Shelby Kritser. From the correspondence I now have on hand, it looks like this is the system Marion Cole installed on N913CB.
I’ll attach four photos taken from a Tradewinds conversion manual. You can see from the cover sheet that it specifies the Aero C-104 and is dated February 1966. Indeed, the photos show the modifications on an airframe that is probably Czech. I recall seeing one of these conversions at Tradewinds but I don’t believe it was this airframe, or possibly it was the same airframe with different cover. I do remember seeing a Jungmann with the pictured paint scheme but can’t recall who’s airplane it was. The list in “Fascination Bucker” is no help so Joe may be the only one to be able to comment on this with any authority.
I don’t have a photo of the engine mount itself but as the airframe modifications are very similar to the Dornier APM, I believe the thrust line very closely approximated the original. If it did, that would make this one of the first high thrust line installations in the U.S. I’ll attach a photo of, I believe, Joe Vasile’s Dornier APM from the Frank Price collection.
Aside from the attribution “Shelby McKrister” on the cover sheet, I have no idea who originated the Tradewinds conversion. I suspect that it may be or may have become the Van White Lycoming conversion. He is just down the road in Lubbock and was Jimmy Franklin’s father-in-law so I know he was familiar with Buckers and the low thrust line Lycoming mounts. Perhaps Frank Price had something to do with it. Although I met Mr. White at SAN a couple of years ago, I never asked him for details. I do know that aircraft attributed to him are modified in the same way. Here is an example in this link:
When I bought my Jungmann it had been modified with an O-320 on an early, long Menear mount fitted with a Van White cowl modified to accommodate a large induction air box. The result was ungainly at best. I agree with Pat Quinn that enlarging the firewall tends to result in a very heavy looking front end that does nothing to enhance the aesthetics of the airframe but, each to his own. In addition my cowl didn’t cool well at all. Especially in the accessory section. In an attempt to rectify all that, I revised the entire engine installation to duplicate the early Woody Menear “Pitts” type cowl like Pat’s early engine installation by John Bergeson.
After the new cowl was well along though, a preliminary weight and balance indicated that even with the much lighter firewall and cowl fitted, my 1000 series airframe would still be nose heavy so I’ve since gone back to square one. I’m now reconstructing around what I call the “Mike Reese” engine mount (photo attached) which is the mount used on the Jay Billmeyer and Wolf Troutman installations. It is 5.5 inches shorter than the early Menear, very close to the late Menear (photos attached) and slightly shorter than the Krybus mount.
I will add that due to the original sloppy Lycoming conversion, my airframe was over-all unnecessarily “Fat”. For instance, my Van White cowl alone weighed 29 lbs! I calculate that with the revised firewall and mount, removal of 12 lbs of ballast in the tail and a new cowl I’m in the process of finishing, I’ll be able to bring the CG back where it belongs and to reduce the empty weight by about 50 lbs. With some other economies, perhaps more! I estimate that in carbon fiber, the new cowl should weigh less than ten pounds complete and as an added benefit, will cool much better than the later Menear cowl from which it is patterned.
All the Best,