Quantcast

Mazda Rotary Engine

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

AIRCAB

Well-Known Member
Joined
Feb 6, 2015
Messages
89
Location
Vancouver Island
Thanks guys, I had to text copy the link, open in browser, then it worked. It must be HBA issue, I can not respond with quotes in, also.

Thanks again, Steve
 

Lendo

Well-Known Member
Joined
Feb 6, 2013
Messages
534
Location
Brisbane
Urquiola, Interesting about secondary air injection - never saw that before, however all it's doing is burning any residual fuel as it's flung into the exhaust.
The standard side inlets do have overlap, as that assists with exhaust extraction like in any combustion engine, the problem is that it also carries fuel with the air, with a standard inlet system.
I notice Tracy Crook timed his fuel to enter the inlet tubes after the Exhaust had closed, hence only air to assist with the exhaust extraction, same problem, fuel burning in the exhaust.
The Rx8 with it's restrictive side exhausts carries unburnt fuel into the next combustion event. As the fuel is flung against the outer wall the apex seals carries it towards the inlet.
The latest Fuel Injection has the injection at the top of the Rotor housing and the high pressure can handle any initial increase in pressure, in the combustion chamber.

I believe a reworking of the depression in the rotor, might eliminate most of the Squish areas, maybe all of the Squish areas, maybe we might see that in the next edition. There is a limit of thickness between housing and Rotor edges (around the depression) that the areas can maintain supporting the flame front, once that's exceeded the flame is extinguished.

Hope that helps to understand for those interested.
George
 

Lendo

Well-Known Member
Joined
Feb 6, 2013
Messages
534
Location
Brisbane
I probably should have said the Hydrogen Rotary development doesn't have any overlap at all, but I thought the reasons would be obvious.
George
 

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
139
Location
NW Oregon
print-screen-dyno.jpg I am amused by the comments made by many on this forum by those knowing of the wankel rotary only through hearsay. Ignorant comments like those made by Starflight and several others make obvious that they don't know this engine, and for reasons I can't fathom want to pass on malicious gossip. Many people make similar comments about 2 strokes, and they are wrong as well. (I can be considered quite knowledgeable about 2 cycles having done engine work for world championship GP bikes.)
First thing to note is the sad loss of Powersport. They were the first group to do a full aircraft worthy conversion. Their mazda based package was the first, and to my knowledge the only automotive conversion ever considered by Van, (Richard Vangrusvigen) to sell as a firewall foward alternate to a lyc for his kit aircraft. Powersport partner Steve Beckham flew back from Osh in their wankel powered RV-4 side by side with Van's demonstrator RV-4. They stopped at the same airports to re-fuel during the trip. the Powersport conversion used LESS fuel at every stop all the back to Oregon. Powersport's Superlight engines weighed in at 178 pounds FF with radiators, but without the exhaust. That engine was p-port intake and exhaust and in the final version produced over 200 dyno proven HP at 6900 RPM. There are many reasons that business efforts can founder that have nothing to do with the quality of the products offered. In the case of Powersport it was the death of one of the founding partners in a non engine related accident. There are several people in the process of developing a new reduction drive. I wish them well. Most of the naysayers have never even seen one of thes engines run. Enjoy,
Bill
 

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
139
Location
NW Oregon
BTW HBA, If it is possible to post videos or MP4s I will post the short video of this dyno run here. It should be noted that there are two versions of this configuration this one being the "small port" version. That is the lower output configuration. these tests were done to check if the restrictive muffler designed to fit under the cowl would run well. it produced 180 hp on the dyno. later the same day this engine fitted with a less restrictive muffler produced 197 HP with the 1-5/8" ports. The other set of housings has 1-3/4" intakes and should prove to make well over 200.
Bill
 

narfi

Well-Known Member
Log Member
Joined
Feb 23, 2016
Messages
943
Location
Alaska
you can post youtube videos here, so if you upload it to youtube, then just use the link in the post or 'insert media' icon in the textbox.
 

thjakits

Well-Known Member
Joined
Jul 3, 2014
Messages
75
Location
Panama, Rep. of Panama
Weeeeell, if you are going to post REP (.... Rotary Engine Porn), than I will just jump the pack and put this up!!

Mind you - NOT an aircraft engine, but a 4-rotor Mazda Race Engine, non-turbo, variable length intakes - that thing won LeMans (before they outlawed the Rotary - ...sore losers!!)
It is also to show the potential of a correctly built Rotary..

BUT - the following video clip is all about "Rotary Symphony" - push up the volume and enjoy - watch the flies, you will be grinning the rest of the day!! :)



....the funny thing is, one is waiting for the engine to spit out all the parts - one is waiting for the operator to up shift (he does, but he goes through all the gears right at the beginning of the run...) - count them at the end of the run, when he is shifting down again...

NO doubt you will want to learn more about this car, so help yourself:

https://en.wikipedia.org/wiki/Mazda_787B

- this gets really interesting from 05:47 on - compare the sound of the RX-8 to the 787 on the dyno - the 787 also appears again - at the very end 12:50 you see a "study in Rotary Engine Exhaust Designing" - with one of the "problems" of the Rotary - dealing with the exhaust!! VERY high acustic energy dynamics, the white spots in the exhaust are the hottests parts, from exhaust itself and augmented by acustic energy (raw decibels and worse ....pulses)

So - from following Rotaries most of my conscious life ( I never built one or even drove one!!) - IF I were to build one for an airplane - it would need to be a specific build - decouple the engine from the PSRU - turbo, constant speed (this allows me to build and fine tune the engine for a few specific rpm areas) most likely all peripheral port, correctly sized and timed (NOTE: the youtube clips are ALL about performance/sport/race CAR engines, aviation applications would be vastly differently built... car engines will exploit the powerlevels around 9000 rpm, for a aircraft engine you probably will redline around 6500,accordingly you will size intake/exhaust, port sizes/shapes/locations)

Unfortunately - MISTRAL ENGINES from Switzerland stopped development years ago - they sold a few units for Experimental use, but lacked the funding to finish their program - google them up!!
This was an all-out professional adempt on a certified engine line up - from 2-rotor normal aspirated Avgas (200 hp) to 3-rotor turbo, Jet-A injection (350hp - ...up to I don't know what altitude!!)
( I had contact with the CEO for a while and we traded quite a few interesting emails - I even tried to connect them with a certain helicopter manufaturer, who at the time was looking for a non-turbine solution for their next size up development. Mistral came up with twin-engine design (2x 2-rotor engines, turbocharged, we were looking for a 350 hp total power level up to about 15000 ft, their design suggestion would have given a 20 min OEI of 300 hp and 5 min 350hp - from either single engine!!, they had that already run on the dyno and the engine didn't brake a sweat. Unfortunately- neither company would make the 1st call.... and rest is history - or an alternate timeline! Mistral closed the doors nad the helicopter sports a turbine today! ...mind you, various redundancies in the engine controls, basically each single rotor was run seperatly - so - even if 3 units would fail - ONE rotor could still provide substantial power in an emergency!)

As it is - I think ANY future ICE engine development will only support existing systems - electric drive is very much on the horizon!! (See - https://www.theverge.com/2019/12/12/21012891/electric-airplane-first-flight-magnix-harbor-air )

The only other ones I hope will succeed are a German Diesel (RED A3,https://en.wikipedia.org/wiki/RED_A03 , ... and hopefully the smaller A5)) and this new design -https://www.ainonline.com/aviation-news/general-aviation/2016-11-08/ain-exclusive-higgs-diesel - to explain the principle http://www.bernardhooperengineering.co.uk/opads.htm )

Also unfortunately - either Jet-A diesel is very EXPENSIVE!!
Successfully converting a car-diesel-engine derived aero-engine is a lot more complex than one would believe - there are a few out there, and it cost them a LOT to get to market...

Now - I suggest before you adempt to build up a Rotary - look up Paul Lamar's website/newsletter (http://www.rotaryeng.net/ - scroll down a few inches and you see a Mistral besides a Lycoming, and right below that you can see the 787 engine!!WARNING - as far as aero rotary is concerned this is a pure ADULT site and highly addictive! ;) ) and read a few decades worth of forum stories to get your Rotary System tuned for "AERO-rotary" - BEFORE you hack that old RX-7 engine apart.... maybe you are still in time for a last ICE hurray - before the evil electric drives take over!! :)

...nough said!

thjakits
 
Last edited:

AIRCAB

Well-Known Member
Joined
Feb 6, 2015
Messages
89
Location
Vancouver Island
Well the video,s on U Tube are not ALL about automotive based engines! As for Paul Lamar, and rotaryeng.net, he did lots to promote, and disseminate information about wankel aviation power! He was also involved with the design of the harmonic coupler used in the TTC aircraft.

Steve

 
Last edited:

EzyBuildWing

Well-Known Member
Joined
Sep 23, 2009
Messages
87
Location
Sydney NSW Australia

Hey guys.... Check the dyno-sheet above!
A turbo'd 13B with light-weight Aluminium-billet CNC'd end-plates can output 150 HP at 3000RPM .
This could direct-drive a 72" Carbon-prop.
No need for a complex and heavy PSRU.
At those low-revs, the engine is loafing...and would last forever. Totally under-stressed.
Ultra-reliable and turbine-smooth!
End-plates are about $3k each.
Turbo chops-up the exhaust noise.
Has to be the way to go!
 

aeromomentum

Well-Known Member
Joined
Jan 28, 2014
Messages
128
Location
Stuart, FL USA

...
At those low-revs, the engine is loafing...and would last forever. Totally under-stressed.
...
Low revs is not the same as low stress. Many engines are limited by Brake Mean Effective Pressure (BMEP). BMEP is one measure of "stress" in the engine. For the same displacement engine, the higher the RPM where you get the power the lower the BMEP. https://en.wikipedia.org/wiki/Mean_effective_pressure

While the wiki talks about the more common piston engine, BMEP is applicable to any positive displacement engine including Wankel and rotatory engines.
 

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
139
Location
NW Oregon
Aeromo,
You are so right about stress levels. something else to consider is efficiency. The rotary is a PORTED engine with all the openings opening very quickly and like other ported engines, (think 2 cycle), they need RPM to run in their best power range. EzyBuild, You could up the pressure and get one running at 3K but it would be likely to get terrible fuel consumption figures. (also remember I like rotary engines but I'd recommend against it.)
Bill
 

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
139
Location
NW Oregon
HBA'ers as i mentioned we did a video of the test bed engine. I wasn't sure if it was still on Youtube. This the muffler built to fit in an RV-3
Bill
.
 

rv7charlie

Well-Known Member
Joined
Nov 17, 2014
Messages
1,003
Location
Jackson
In addition to the BMEP and efficiency issues, there's the issue of prop interface. While the E-shaft is a lot stiffer than a typical crankshaft, hanging a prop on it introduces a very big unknown, at best. Many worry about thrust loads and thrust bearings, but a much bigger issue is *bending* loads on the crank/E-shaft. A Lyc crank's 'thrust bearing' is a shoulder on the crank running against the engine case. But its bearing that isolates *bending loads* from the crank throws is about 4" long. Think of it as a couple of sleeve bearings that are about 3" apart. In addition, a prop bolted directly to the E-shaft will have a quite large diameter area within inches of the prop, having an adverse effect on prop efficiency. The typical cure for this, a 'prop extension', will aggravate the bending load issue.

You can get a pretty good idea of the seriousness of bending load issues by looking at crank breakage issues in direct drive VW & Corvair a/c conversions. Many (most?) of the successful conversions are now running an additional bearing with and effective extension on the nose of the crank, to isolate the bending load from the crank throws. You rarely see crank breakage issues with Subarus, because Subarus almost always use reduction drives.

Finally, an all-up normally aspirated 13B ready to fly will weigh around 330 lbs (I can show you a pic of engine and scale). Adding a turbo will push the weight well beyond 350 lbs. This is still 'in the ballpark' of O-320 Lyc weight, but it's now a much more complicated engine, limited in takeoff performance by smaller prop diameter (3000rpm vs 2700 for full power).

Charlie
 

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
139
Location
NW Oregon
Charlie, You are correct about thrust bearing issues. The Mazda rotary doesn't have much in the thrust bearing department. The reduction drive has tapered roller bearings to allow thrust in both directions.
Bill
 

Attachments

AIRCAB

Well-Known Member
Joined
Feb 6, 2015
Messages
89
Location
Vancouver Island
YES of course - just go to youtube and put anything you like inthe search window - if there is NOTHING on youtube - ...it doesn't exist! :)
You had to be on Paul Lamars email group to appreciate the development of this projects. Lots of nay sa
YES of course - just go to youtube and put anything you like inthe search window - if there is NOTHING on youtube - ...it doesn't exist! :)
YES of course - just go to youtube and put anything you like inthe search window - if there is NOTHING on youtube - ...it doesn't exist! :)
You
YES of course - just go to youtube and put anything you like inthe search window - if there is NOTHING on youtube - ...it doesn't exist! :)
Had to be part of Paul Lamar,s email group to appreciate the development of this project. Lots of nay sayers,s in the beginning, but all seem to have gone silent!
 

pictsidhe

Banned
Joined
Jul 15, 2014
Messages
8,812
Location
North Carolina
Aeromo,
You are so right about stress levels. something else to consider is efficiency. The rotary is a PORTED engine with all the openings opening very quickly and like other ported engines, (think 2 cycle), they need RPM to run in their best power range. EzyBuild, You could up the pressure and get one running at 3K but it would be likely to get terrible fuel consumption figures. (also remember I like rotary engines but I'd recommend against it.)
Bill
Best power and torque rpm for ported engines, as well as valved, depends on port size and timing. It is quite possible to make a low rpm rotary, with smaller ports. Making ports smaller tends to be much harder than making them bigger, though...
 

pictsidhe

Banned
Joined
Jul 15, 2014
Messages
8,812
Location
North Carolina
Low revs is not the same as low stress. Many engines are limited by Brake Mean Effective Pressure (BMEP). BMEP is one measure of "stress" in the engine. For the same displacement engine, the higher the RPM where you get the power the lower the BMEP. Mean effective pressure - Wikipedia

While the wiki talks about the more common piston engine, BMEP is applicable to any positive displacement engine including Wankel and rotatory engines.
I calculated rod stresses on Briggs V twins, combustion forces are bigger than the inertial forces.
 

rv7charlie

Well-Known Member
Joined
Nov 17, 2014
Messages
1,003
Location
Jackson
There's usually a good reason why some 'simple' idea has never been tried before, and that reason is usually, that it has. Or there's an obvious reason (to the engineers) why it hasn't.

You can make a low rpm rotary. It'll just be a very low power/weight rotary. Mazda has spent over 50 years tweaking it for optimum performance. If they could have built one with more bottom end power for automotive use, it would have happened. If you're familiar with the breed, you know that the intake system is almost as big as the core engine, solely to get low end & midrange torque up enough to be useful in a car. That includes primary and secondary (and in some engines, 'thirdary') ports, with different timing. At low rpm, the porting, and runner length, are already optimized for low rpm.

The torque you get is what you get, unless you massively boost the engine. Torque in a rotary is relatively low, compared to most piston engines; somewhat analogous to a turbine. Its power comes from the rpm portion of the HP equation.

You could make a low rpm turbine, too. But you won't find any in production.

Charlie
 

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
139
Location
NW Oregon
Guys Powersport was doing the best “low RPM” wankel porting. They were tuning for 6000 RPM. They finalized at 208 HP at 6500 with very small ports. Keep in mind that all your parts need to handle that 200 HP.
Bill
 
Top