rotary mounted on its side?

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Peterson

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If one were to use a dry sump oil system and use pre-mix fuel, do you think a rotary could be mounted spark plugs down? With the exhausts ports on top it would be easy to get a lot of heat out from under the cowling and it would be simple to build an intake. This profile is more similar to the opposed piston engine. Eventually I'd like to try to cast an air cooled case out of aluminum that would use 13B internal parts that would benefit more from this layout, but are there any issues that would make turning a rotary on its side less than ideal?
 

TFF

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Memphis, TN
Plugs on the bottom could have fouling problems if fuel and oil settled in while shut down. I doubt there would be any other problem. You are either going to be able to cool it or not. Lots of fins and heat sink area or it will burn up fast.
 

JamesG

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Yeah, plugs on top would be better. Where the exhaust is located really doesn't make much difference in cooling. Its the volume of air passing over the heat exchange surfaces that matters, not the temperature. Air has a very high heat soaking level. This is why you can put oil coolers and exhaust manifolds in front of aircooled engines without too much trouble, but passive convective cooling isn't going to do the job.
 

Will Aldridge

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Here is an article by a gentleman who put a rotary in a Lancair 235 plugs up. There are certain considerations regarding the cooling passages and their orientation that need to be addressed. I can't remember right now exactly what the potential problems are but I think it has something to do with steam pockets getting trapped at the top since the engine wasn't designed to be in that orientation. If you vent it properly or something along those lines you might be okay. Obviously do your homework on it. Paul Lamar the guy most identified with rotary engines runs a website and newsletter and I've heard (second hand so verify for yourself) that he is opposed to plugs up.
 

wizzardworks

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center-housing-cut-away.jpgPeterson, Plugs up works but a modified oil pan and pick up tube are needed. I don't like the idea of having the exremely hot rotary exhaust and possibly oily residue of
combustion impacting the windshield if the block was mounted plugs down. Also any oil settling in the rotor chambers after you shut it down will drain into the spark plug openings. The attachment
shows how 90 percent of the oil exits the block. The rest goes thru the bearing clearances in the front and rear end housings. The reason for "plugs up" was to get the distributor located where
it wasn't sticking thre the top of the cowl. Mazda changed to crank trigger ignition and those parts were adapted to earlier built engines making plugs up unnecessary.
wizzardworks
 

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Peterson

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May 25, 2014
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St.Rober, MO
Valid points. I personally never shut a rotary off at idle and believe this would prevent plug fouling issues with a plugs down arrangement, but just like any engine with factory designed oil passages a change in mounting orientation will compromise the oil system's effectiveness.

I have been looking into aluminum casting processes and was wanting to design an air cooled case that could use 13B rotors and hard gears and already be ported to run in the 6,000 rpm range making it ideal for the readily available PSRUs. The inside would probably be ceramic lined for additional heat protection with a heavy duty oil cooler and lots of cooling fin area.
 

jetboy mike

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May 12, 2013
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Everett Washington
WAY back when I was a lad we had a couple ArcticCat snomobiles with air cooled rotary engines that really went across the snows well. Replaced apex seals every other season and of course they were a bit thirsty but Grandpa was buying the gas. They were happier the colder it was and at night the exhaust would have a cherry glow under the engine where you could see the tube elbow right out of the exhaust port. It was listed as a 303cc motor but would stomp the 440's all day. The radius of the motor cooling housing was twice the diameter of the core and the engine diameter was about the same size as a 13B while the rotor itself was about a third the size of the 13B's. I know it won't scale directly but that leads me to believe that an air cooled made from 13B parts is going to have a circular cross section like most flat motors.

Interesting, hope you can prove me wrong...

jet
 

wizzardworks

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murfreesboro NC USA
AR731.jpgIMG002.jpgIMG021.jpgIMG027.jpgIMG018.jpgPeterson, Image 1 is an example of an aircooled rotary.
There are also charged cooled rotarys which circulate the fuel/air charge thru the engine core before firing it. They seem to be low HP compared to their displacement.
The rest of the images are some of the patterns for my 6 rotor engine. The real challenge is keeping the oil, air, and water separated in the engine core. Image 4 shows
the revised port entry that replaces the 90 degree elbow used by Mazda to house a rotary intake block off for low RPM. The patterns are done in slices like images
3 and 5 then stacked up. Side housings are two "O" ringed pieces open cast and joined to eliminate cored castings. Everything is machined on the little lathe in
image 3 which is a LeBlonde 27" X 113". The MFS 398 alloy has the tungston carbide nodules as a wear surface after lapping. There have been some problems with
ceramic coatings on flat surfaces with heating and cooling cycles.
wizzardworks
 

Peterson

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St.Rober, MO
6 rotor?!?! Sounds beastly! I have seen some Sachs 303 rotaries that seemed to be fan cooled. I know that RX7s run MUCH cooler with louvred hoods as hot air surrounding the engine is drawn out of the engine compartment and it would seem that if air could be removed from under the cowling as fast as it enters, an effective tunnel ram cooling could take place increasing the plausibility of such design. A prop forcing air through would help with keeping temps down on the ground while cruising at 130-150 mph should provide plenty of cool air in flight. At least in theory.

I really only know about basis green sand aluminum casting and only have access (at least for now) to low grade recycled aluminum so the best I could do any time soon would be a scale model. Still, thanks. Wizard for some great information, if I get a chance to attempt to build this I'll be trying to get in touch for more in depth info.
 

wizzardworks

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Nov 8, 2011
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murfreesboro NC USA
Peterson, You can put the radiators down the plugs side of the engine and use wedge difusers with the louvers on the cowl side. As for letting a lot of unducted air into the cowl, that is a very large cooling
drag penalty. The plan for the 6 rotor is two 3 rotor modules with doweled connector belhousings in image 2 above and a faulk grid coupling between the shafts. I could also do a four rotor similarly derated
to 530 HP normalized. Fuel burn numbers are scary high on the 6 rotor.
wizzardworks
 

Peterson

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May 25, 2014
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St.Rober, MO
I am curious, what are you building that requires 530-650 Hp of a 4-6 rotor? Sounds like you're wanting to cruise at around 400 mph :ponder:
 

wizzardworks

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Nov 8, 2011
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murfreesboro NC USA
Peterson, Only 340 MPH at sea level density. It is a large 4 surface canard with a 165 square foot main wing. There is an X-plane folder of it on Duncan's X-Plane thread.
wizzardworks
 

Billrsv4

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Sep 29, 2016
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NW Oregon
Peterson,
While with dry sump you can mount the rotary in almost any position, you would find it vastly easier to work with in the stock or plugs up orientation. When you commit to running plugs up, with EFI or mechanical FI you have very easy paths for the intake and exhaust. I am working with one of the original partners of PowerSport. They ran the rotary in the plugs up orientation in one of their earlier "superlight" engines. The tried almost every set up you can imagine, To work with one of the gearbox options they even ran it backward! To make a more affordable package they went back to a standard orientation. The problems you would face mounting one plugs down are many and varied, Trust me you wouldn't want the headaches. Mind you it could be done, but as several other posters have mentioned it probably isn't worth it. If you don't run your own machine shop you would be biting of a chunk that is bigger than you want to face unless you have a few years to work on that alone.
Bill
 
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