I
Jongbloed Reducer With roots in the world of auto racing, a new gear reduction unit . . . mated to the Mazda 13B by Bill Jongbloed Jongbloed Aviation Box 40, Chino Airport Chino, CA 91710 First a bit of an introduction as the name Jongbloed is actually pronounced "Youngblood". I'm Bill Jongbloed and my background is in automobile racing and spans 23 years. The last 12 years have been devoted to the manufacturing of modular racing car wheels, however, prior to this I was an active racing car mechanic and fabricator. Since aviation is where I've wanted to be since childhood, entry into the market seemed a natural. Also, having witnessed first hand the development of both Chevy V-8 and Mazda rotary engines made me feel that they were both quite suitable for use in experimental aircraft.
Once the decision was made to develop a reduction drive unit, a decision had to be made between cog belts, Hi Vo chains or spur gears. Belts seemed to be the simplest and I had lots of experience with them as accessory drives on race cars. We found, however, that to harness 200 BMP required a 6.0 inch wide belt. That wasn't too bad, however, my intent was to eventually harness up to 750 BMP and this would require about 22.0 inches of belt width! Chains were next up and weren't as bulky as belts but it was becoming apparent that gears would still be the best all round solution. So gears it would be and thought was initially given to using gears from a Muncie 4speed automotive transmission. That became a fleeting thought as it became apparent that, short of bearings and seals, the gear reduction unit would be best if all component parts were designed and built from scratch. My father is a retired aerospace mechanical engineer, so I joined forces with him and asked a friend of mine from racing named Pete Weissman to
look over our shoulders. He agreed and the design was begun. Pete, by the way, designs and manufactures probably the best and most exotic racing car transmissions in the world, from TransAm racing right up to Formula One. Our layout was to be a very simple, strong and compact design using straight cut spur gears with a quillshaft to isolate the harmonics of the crankshaft (eccentric in Mazda) from the gears and prop shaft. The quillshaft is very critical as, for instance, any change in the crankshaft will also require a change in the quillshaft. This simple approach also enabled us to complete the program in a reasonable length of time (our spare time). Our gearbox layout raises the propshaft up 5.0 inches vertically and offsets it to the left 1.0 inch giving extra room around the exhaust system. This 5.0 inch vertical offset also allows all of the Mazda accessories, such as water pump, carburetion, alternator, oil filter and foil fill neck, to remain in the stock location. This goes a long way towards minimizing the homebuilders already large task SPORT AVIATION 21
Jongbloed Reducer at hand. Joining the reduction unit to the Mazda engine is a bellhousing of our design. Incorporated in the bellhousing are Lycoming type compression mounts that act in concert with another pair at the rear of the engine (front in the car) to complete the mounting of the powerplant and gearbox assembly in the airframe. A stock Mazda starter motor is used along with the automatic transmission flywheel. Now, let's look at the powerplant itself. The Mazda 13B engine was chosen because of its turbine smoothness and its compact design. It is also an expandable design and, in fact, a three rotor version is currently being raced by the Mazda factory. My guess is that within 2 years these engines will see introduction in the passenger car market and aircraft are only a natural at that point. This version is called the 13G, more on this later. The Mazda engine is very simple mechanically, however, it can't be run backwards so one important note is that you will need a counterclockwise propeller. Fred Griffith of the Great American Propeller Company assures us that this causes no hardship other than simply ordering the right prop. Our conversion of the Mazda utilizes turbocharging. The reasoning is twofold as we not only wanted to offer an engine with superior performance at altitude, but also to muffle a non-turbocharged Mazda requires an act of God plus about ten feet of tubing and mufflers. The turbocharger does a commendable job while boosting performance. This noise business is really important and seems to be often neglected. Since noise is a byproduct of fuel, let's discuss fuel consumption. A properly tuned Mazda will have fuel specifics of .55 to .60 Ib./hp/hr. and since it is liquid cooled, won't need to run rich for climb. That sounds high, however, in his forum last year at Oshkosh, the AVCO-Lycoming man stated that while an air cooled motor may cruise at .45 Ib./hp/hr. if you checked consumption on the entire flight or "mission", as he put it, the total fuel burn would average .55 to .60 Ib./hp/hr. Doesn't that sound a lot like the supposedly thirsty Mazda? The next subject is how fast will it turn? Mazda's are quite happy to run for long spans of time at 5000 to 6500 rpm but they get tired really quickly if
they are spun faster than that; I don't care what the guy in the bar tells you, 22 JUNE 1987
Bill Jongbloed
he probably has the wrong tachometer! A Mazda set up such as ours will produce 170 BH at 5000 rpm and 200 BMP at 6500 rpm. Remember that there is no magic, so cast a wary eye towards those claims of 300 BMP and 250 pounds. To reach those HP levels you must spin 9000 to 9500 rpm and that only happens on racing tracks in racing cars. My engine consultant is Clayton Cunningham of CCR racing whose motors are about the best in the business and he says 6500 rpm. As far as 250 pounds goes, it's true but that's a race engine without an aircraft gear reduction. What dwells under our turbocharger is a basically stock 13B motor with a mild port job'plus one mandatory modification. There are some planetary gears inside the motor which must be exchanged for their hardened counterpart. These gears are available from a variety of sources but they are a must. Carburetion is at this time experimental, however, an automotive Holiey 2 barrel seems just fine unless aerobatics are your desire with negative GS. Now, let's return to the gear reduction unit as we've just talked about rpm. Our unit is geared at 2.29 to 1.00 which means that you will have a propeller turning 2875 rpm for takeoff (6500 engine rpm). Cruising at 5000 engine rpm will give you a propeller turning 2183 rpm. If you ever wondered why gear ratios seem odd, such as 2.29 or 4.56, the reason is this. The term "prime numbers" means that each tooth of, say, this pinion gear will, with each revolution of the gear, move over one tooth so that each gear tooth will contact every tooth on the opposing gear. This greatly reduces the wear of the gears and is why gear ratios are always odd, such as our
2.29 to 1.0 ratio. Speaking of gears, ours are machined from 8620 steel and carburized. Our shafts are machined from 4130 and 4340 steel then heat treated and ground to finish size. Oiling is by splash, however, provision is made for pressure oiling should that be desired. Hydraulics can also be provided for constant speed propellers although great hope is placed on the new electric constant speed propellers being developed by the Great American Propeller Co. of Oceano, CA. A prototype can be seen on our test engine and considerable testing will be carried out in cooperation with Great American. Cooling, radiators and plumbing have for sure turned many homebuilders off to automotive engines, and for good reason. Designing a proper cooling system is a major task and is another neglected area. Towards this end, we embarked on a universal cooling pod assembly that looks like the belly scoop from a P-51 Mustang. This was no mistake as the Mustang cooling system actually developed thrust from its hot exhaust air. This is called thrust recovery and in the case of the P-51 was reputedly worth 150 BHP! So much for having to design your own, and remember our pod assembly can be shifted fore or aft to achieve the best weight balance prior to final installation. Our pod is also narrow enough to fit under the fuselage of a Long-EZ. Continuing on the subject of weight, let's now look at powerplant weights. According to Jane's, a Lycoming 0-360 weighs 268 pounds and produces 180 BHP. That's fine but put that engine on a scale with oil, exhaust and acessories and it will read 325 pounds. Besides, once you are up to 10,000 feet, your available power is 125 BHP, giving a
powerplant power-to-weight ratio of 2.6 lb. per hp. Now, by installing our Mazda conversion, your engine-gear reduction weight, including oil, water, turbo system and accessories, will be 330 pounds forward of the firewall and 50 pounds aft in the cooling pod. You will have turbine smoothness, better aerodynamics up front where it counts and 200 BMP at 10,000 feet. Total package weight is 380 pounds, giving a
power to weight ratio of 1.9 lb. per hp. Remember, too, that the cooling pod will be virtually drag free due to thrust recovery. Mounting of any powerplant requires a proper motor mount and cowling. The mount that you see in the accompanying photos is designed to fit a Lancair kit. We have been getting cooperation from Lance Neibauer (Neico Aviation), Van's Aircraft (RV-4) and a fellow named Richard Cabrinha who has a
new kit called the Free Spirit. Interest has also been shown by White Lightning, Air Shark and numerous Long-EZ builders. Our intent is to produce motor mounts, cowlings and cooling systems so that the homebuilder can get on with building his kit in a reasonable length of time. In a future article the testing phase will be discussed, so until then I'll stop writing and get back to work. See you at Oshkosh '87, Booth C-4.
WE SHALL REMEMBER THEM RICHARD J. OLIVER (EAA 114964),
Woodstock, GA. January 22, 1987. Member of EAA Chapter 268. FRANK L. PARET (EAA 260773), Silver Lake, NH. January 23, 1987. JOHN J. DOWD, SR. (EAA 123075), Warwick, NY. January 24, 1987. EDWARD NEAL BOUCHER (EAA 260558), Valley Heights, AZ. February 9, 1987. NICHOLAS PUZZELL (EAA 167820), Basking Ridge, NJ. February 23, 1987. ELMER NEIBECKER (EAA 3830), Morton, IL. March 2, 1987.
CARLTON
K.
PATTERSON
(EAA SHELBY
212506), Gloversville, NY. March 3, 1987. Member of EAA Chapter 602. GEORGE VUXTON (EAA 183894), El-
mira, NY. March 17, 1987. Member of EAA Chapter 533. ARTHUR G. HODGE (EAA 238708),
Janesville, Wl. April 6, 1987.
KENNETH FLOYD CHENAULT, JR.
(EAA 110655), Dallas, TX. April 11,
1987. ROBERT T. SPRAGUE, JR. (EAA
HAGBERG (EAA 2473), Greenville, IA. April 12, 1987. ALEXANDER YAREMA (EAA 38443), Allentown, PA. April 15, 1987. Member and Co-Founder of EAA Chap-
ters 70 and 855.
STANLEY C. MOCKRUD (EAA 8567),
Madison, Wl. April 20, 1987. Member of EAA Chapter 93. DEAN A. BOHRER (EAA 90442), Toddville, IA. April 20, 1987.
111230), Williamstown, MA. April 12, 1987.
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