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Mazda Rotary 
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Has anyone been able to get a Mazda rotary to run with this system- or will I be out here alone? Specifically, I would like to know if anyone has the code written for the stock Mazda rotary CAS, (2 primary and 24 secondary teeth with none missing) for ignition events every 360 degrees/ rotor? Like a 2 stroke.


Wed Apr 03, 2013 3:25 am
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What do you mean by "this system" exactly? A little education for me: How often does the 24/2 pattern complete? Once every 360 or once every 720?

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Wed Apr 03, 2013 1:20 pm
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Ahhh, I see your sign up info. This is the wrong section, I'll move it after you post again.

If the answer is "once every 720" then there is nothing left to do regards events. FreeEMS is different from other setups, nothing is specific, everything is generic. Rotaries are not special in this regard.

Because you're not doing trailing spark plugs separately, you have enough channels to do what you need to do. You'll also need some staging code, however Sean has written some code for that that he is using, simple but effective.

Fred.

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Wed Apr 03, 2013 1:29 pm
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Thanks Fred for the input. I have been building this plane for over 2 years and am trying to complete it. I know from your other posts that you are familiar with rotary engines. I was reviewing the code last night for the missing tooth wheels and they all seem geared toward a crank or cam sensor that fires based on normal recip 4 stroke engines- meaning firing every other revolution and 720 degrees between firing events. As you know the rotary fires each rotor face with each crank revolution. I was trying to see if anyone had written code for the original CAS with no missing teeth so that I wouldn't have to re-invent the wheel. If I had to write it, I would use the top tit of the CAS as the synchronizing point, and the lower as the counter. The rotary CAS has 2 tits at 180 on top and 24 teeth on the bottom, and turns at half engine speed. I am sure you know all this. My other issue is the time between firing- I need a minimum of 7500 and more like 8000 rpm for takeoff, and 6000 for cruise. that is an interval of .0075 seconds to read the CAS, MAP, Outside temp, coolant temp, intake temp, atmospheric pressure, figure the fuel, trigger the spark, and reset.

I will look for Seans code and see if it might work and post again. I did a search for rotary engines and did not see it.

By this system I was referring to the FreeEms. I am getting up to speed on the system through the forums, and from reading the code. I will have to add a few parameters specific to airplanes- like default sensor variable values that will enable us to land in the event of sensor failure, etc. I also have to read OAT, since it gets really really cold in the northern latitudes at 15000 feet. My initial tendency was to do this through calculation rather than a table, but CPU resources and interrupts are causing delays.

I saw on another post where someone was asking about "fly by wire" full throttle control. That is my ultimate goal. One position for takeoff power, one for cruise, one for flight idle or descent, and one for idle or landing. There will be a sort of manual over ride for ground movement, emergencies, etc.

Kevin Alderman


Wed Apr 03, 2013 2:11 pm
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the 24/2 pattern- I answered the question but it was inside the rest of the response.

The top ring of the CAS has 2 teeth 180 apart with a single mag pickup.
The bottom ring has 24 teeth with a single pickup.
The CAS turns half engine speed, so it would be 720 degrees.

Thanks for the work on this project. I couldn't use the MS system because I cant change it like I need to. A lot of aviation guys are tired of paying 50K for engines designed in the 40s, and are trying to develop an alternative. I am hopeful this project will work-

Kevin Alderman


Wed Apr 03, 2013 2:15 pm
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Again, you don't read a decoder to find out what can be scheduled where. If the decoder knows about 360 degrees, then that's all it can fire in. If that's all that you need, you're good to go as is. And yeah, very familiar with the NipponDenso 24/2 CAS ;-) Rotaries are pretty un-special, however we've not had one run yet, so you could be the first :-) Read this: viewtopic.php?f=54&t=1084

As for sensor overrides being air-plane specific, that's far from true. Virtually nothing is special about being in an aircraft either. Not entirely true, but mostly true. I've got some plans to do that, and do it well, however if you need to hack something in in the mean time, go ahead :-)

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Wed Apr 03, 2013 3:59 pm
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Would you stay with the OEM CAS or go to a hall effect sensor and toothed wheel?

Or another way- do you know of any bad issues with the CAS? This engine can expect many hours at 6000 RPM without a break until landing.

Kevin Alderman


Wed Apr 03, 2013 4:58 pm
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Stick with the CAS, a proper VR setup is superior to a hall setup, despite what various M$ using idiots may say. The OEM stuff is likely way more reliable than anything you can rig up yourself, too. As for RPM, those CAS units are also used on 4AGE engines that spin 8k and when raced never drop below 6k. I'd be much more worried about your apex seals :-)

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n00bs, do NOT PM or email tech questions! Use the forum!
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Thu Apr 04, 2013 12:24 pm
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Fred- in our developer notes you made the comment about everyone using the images that you have on the github page. Do you have an image for the Mazda 24/2 CAS? I would like to start with a baseline image before I start hacking, it might make things go faster from this end. After the system is tested and working, then I can make modifications specific to what I would like to do with my plane.

I have been busy with other peoples planes, and havent had time to work on mine. I even ordered the VR chips, but dont have time to make a board. I ended up buying one from Jean Belanger and when It gets here I will finish assembling the boards and start testing.

KA


Sat May 04, 2013 2:45 am
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Image as in photograph or firmware?

http://builds.freeems.org/firmware/dev/images/ grab PRESTO or SNOTROCKET images and it will work with your dizzy, which btw, is Denso/Toyota, not Mazda, and used only on the F2T engine and rotaries :-) In contrast variants of it are used on most Toyotas between 88 and 98, maybe newer stuff too, unsure.

Fred.

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DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Sat May 04, 2013 9:49 am
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