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Mazda 13B rotary discussion

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Dan said:

>Should I buy a "scrap" engine and rebuild, or look at a >proven "aero" rebuilder? (I have a qualified car mechanic next door >who is very willing to help :-) )


Engine rebuilding is a skill I didnt want to learn. There are quite enough learning curves and challenges in building without adding this one. Given that the engine is THE most critical single component in the airplane, I decided I didnt want to fly my first ever rebuild attempt, so I had my engine rebuilt by an expert for about the cost of a good nav/com. While most flyers are using 2nd gen engines, I think that there is significant value in getting the 3rd gen REW ('93 or better) engine which is fairly rare in the US. Mine was imported from Japan. I'd recommend coordinating getting a 3rd gen core to Bruce Turrentine and have him rebuild the engine for aviation use. Bruce made the how-to video on 13Bs and is Tracy Crook's vendor of choice. What more can you ask? (see link to Bruce's email on my web site links page). Of course, there's the RX8 renaisance (4th gen) engine coming out this year. If you're just starting out building, this may be the one to shoot for.


Cozy IV mounting is now standardized by conversion concepts. Electronic fuel injection and redrive are available from Tracy Crook (and flown by him in his RV). Igniters are from a 92 Corvette. For exhaust I'm using a turbo and a straight pipe (similar to Greg Richter's Cozy III) except that I'm using the stock 2nd gen T03 turbo and a manual waste gate. I still have to fit the intercooler in somewhere. Cooling is still an experimentation thing. I'm using two stock mazda oil coolers, a big aluminum aftermarket rad and an electric cooling fan from a Ferrari. I'm HOPING to achieve adequate cooling and minimum possible drag by using a cowl flap arrangement and exhaust augmentation, feeding everything from the plans NACA without adding big P51 scoops all over the cowl. Electric water pumps are sounding very interesting. Prop is a serious laminated wood screw from Performance Props set for an initial max power level of 280HP. (The PP prop looks good, but I might go with Catto if I were doing it again). Intake is getting close to standard. I hope to have mine soon. Cowlings are still do-it-yourself, but its fun and fairly easy to do compared with building a spar or a wing. I might take molds off my cowlings one day. There's lots of discussion and pictures on my web site http://kgarden.com/cozy/chap23.htm


Overall advise for new builders considering a rotary....

Get on with building you're airframe. Delay the decision as long as possible while keeping an eye on developments in the rotary world. Don't waste you're time reading the Rotary Newsletter. Join the flyrotary newslist, get contact magazine and Central States. Visit Tracy Crook, the Cozy Girrrls, Greg Richter (Blue Mountain Software), myself and any other "Wanklers" you can find. Take a look at the rotary installations at fly-in's, but dont copy the plywood intake plenums and automotive hose clamps you'll see there. Don't get into this to save money. Plan to spend almost as much on you're 13B firewall backward installation as you would installing a low time Lyc. Plan to save a LOT on on-going maintenance.


I hope all the above helps.

As always - I'm wide open to questions, comments, suggestions, critisism and absolute ridicule.


John Slade

I can be reached on the "other" forum http://canardaviationforum.dmt.net

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This is slightly off topic, but you do mention propellors... Has anybody tried an Ivoprop with a Mazda (or Subaru for that matter)? I have heard that they aren't recommended for large 4 cylinder aviation engines (ie IO-360) because the power pulses are too large, but with a rotary I would assume this wouldn't be a problem.


To me they look like a very nice way of getting a constant speed prop without the huge cost. I laos think that its really cool that you can easily add/remove blades from the prop.

Rui Lopes

Cozy MkIV S/N: 1121

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>Has anybody tried an Ivoprop with a Mazda

Not that I've heard of. The other thing I've heard about IVO is that they're not all that efficient at cruise / WOT. i.e. you'll get better top speed with a wood prop. The adjustable pitch will get you better performance for take off and maybe climb, but on the other hand, Greg Richter gets off the ground REAL fast with his Turbo and fixed pitch even though his prop is a couple of inches short due to a repaired crack. Add this to the stories of blades breaking off for whatever reason, and added complexity and I decided on fixed pitch.

I can be reached on the "other" forum http://canardaviationforum.dmt.net

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Dont EVER consider a Ivo. Look at the NTSB reports on prop failures and you will find Ivo leads the pack. I dont know how that guy keeps insurance on his buisness...


John is right, the only advantage of a controlable pitch prop is take off performance. With the amount of hp we have in our planes improving take off performance should not be a consideration. Fixed blade props are designed for cruise performance so an adjustable would not be an improvement in this area. They are really not worth the weight, cost or maintence headaches...

Regards, Nick


Charleston, SC LongEZ, N29TM, 2400 hrs


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Glad to see more rotary discussion. I am still working on the airframe. Tracy's ignition and redrive are sitting in their boxes in my computer room unitl time. A friend is welding on my second engine mount design, dubbed the Mk-2. I am building a Long so conversion concepts does not have my mount, they do seem to do nice work however. Still debating my intake manifold design, probably use the stock lower manifold, a racing style wrap over, and then build a composite runner with an automotive style throttle body on the end. I ran this past Tracy up at his place and he said that sounded like it would work well., (Good enough for me) Exhaust will be a pretty straighforward welded pipe with a muffler added. I plan on using the John Slade method of gobs and gobs of pour foam and then sanding for an original shaped cowling. NACA scoop and aftermarket aluminum radiator, with a Mazda or lighter aluminum oil cooler. Still debating the radiator cooling fan idea for cooling during taxi, I am in Florida so that is a concern always. Keep up the good discussion here. See pictures at http://mevans28.tripod.com


Matt Evans

Clearwater, Florida

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>using the John Slade method of gobs and gobs of pour foam

Actually I used blue wing foam scraps and "great stuff" from home dept., then covered the whole thing with sheetrock putty. You'd use a lot of pour foam to make a cowling. See pictures of my cowl construction at http://kgarden.com/cozy/cowl.htm

The cowl is the fun part!

I can be reached on the "other" forum http://canardaviationforum.dmt.net

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The CONCEPT of the Rotary is fascinating. Small size, low weight, good power, spinning instead of recipricating parts, et. al. The EXECUTION of the idea is the problem.


I don't have experience with the engine in the aircraft world, but the engines are auto conversions (mostly) and I do have experience in the automotive world. They seem to have continuous cooling and oil seal problems. (Check the extended warranty rates) I've seen several sites raving about the rotary engine in an aircraft... only to find a mention in passing about an oil leak or cooling problem. Scary...


Count me in the Sooby conversion camp. No offense intednded, My 02...

<--- *Most opinionated member who hasn't even ordered plans yet!

This ain't rocket surgery!

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>seem to have continuous cooling and oil seal problems

Cooling "issues", certainly. Every installation is an innovation thus far and there seem to be some tricks to cooling a water cooled engine both during take-off and then at 200 mph cruise. I think we're getting closer to the answer here. There are quite a few 13Bs buzzing around the sky consistantly these days. The oil seals I've heard about have been lost during the early cooling experiments. Again, current rotary flyers (Atkins, Graham, Crook, Lassen, Richter to name just a few) dont seem to report these problems except during initial innovation stage that they all had to go through.


Keep in mind that the 13B is installed in a sports car. People tend to thrash sports cars, taking them up to peak power quickly and repetitively. When used in an airplane the engine won't be running at more than 6000rpm, just over 50% of its normal max). True, we'll be drawing more HP from it on a continuous basis than a car will ever get, but then the engine is very robust so catastrophic failure isnt likely. I've added 3mm seals instead of the stock 2mm. Also, I'm using a 3rd gen engine which has better oil galleries.


There's definately a lot to be learned about the rotary and aviation, and its not a direction (yet) for those who want to keep it simple and just fly.


I hope to add to the knowledge base soon.

I can be reached on the "other" forum http://canardaviationforum.dmt.net

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