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dsm8

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I recently read an article regarding the instillation of a Mazda RX motor in experimental AC and was wondering if anyone has any experience, postive or negative

Thanks

Don
 
Don,

My business partner has a rotary in his RV-6A. He was the 2nd one to fly with one, behind Tracy Crook. He will tell anyone who is thinking about putting an auto conversion in their airplanes that these engines are for people who like to tinker. If you like to fly, he suggests you stay with a Lycoming.

With almost 500 hours on his rotary, he has more RV glider time than any RV pilot I know. Each time he has landed on a runway and each time the problems have been related to the systems, never the core engine.

If you want a rotary, go for it!


...and let us know how it works out.
 
was that an article in the Rvator? if not, there is a write up in one of them. i'd have to search it to find it.
 
Doug Lomheim is building 9 with rotary, impressive piece of engineering. He is an active participant under Dlomheim here. You may contact him off line he will gladly talk to you. Also there was a beautiful RV4 with Mazda rotary for sale a month ago. I bookmarked the pics and will try to locate them tonight.
 
I think I read the article you are refering to in Sport Aviation. To me, it sounded like the conclusion was that rotarys:
1) weight about the same as a Lycoming
2) produce about the same HP as a Lycoming
3) burn the same amount of fuel per hour as a Lycoming
4) MIGHT cost less - if you get one from a junkyard
5) Will be SIGNIFICANTLY more work, including a good bit of engineering and fabrication.

So........
 
rotary RVs

We have two RVs with rotary engines on our airpark. They are successful installations. You will not find any of them active on this forum because of all the criticism they get from the experts that have never done an installation. I believe they have a web site where you can visit with these guys.

Good luck.
 
RV-9A w/13B

I'm afraid I'm guilty of operating outside the normal boundaries of the experimental movement and have been working for the past 11 years or so to complete a 9A w/a Mazda 13B engine. If you look at my serial number you'll know this task isn't the quickest way to go (90116). I would estimate that going the rotary route has added about 400 hrs. to my project due to the requirement to fabricate a cooling, exhaust and intake system. Using the original Mazda components really isn't suitable due to the tight under cowl space found on our RV's and their high weight.

I went the rotary route mainly because I was impressed by its' simplicity, smoothness, and potential to save costs on the front end and over its' life (overhauls should cost less than $1500). I initally considered Eggie Subie engines but wasn't willing to pay $16K+ for something that had just as high a parts count as a Lycoming. If I were doing a rotary installation right now I would use an RX-8 Renesis engine because it will be newer and also it can be made to run extremely quietly as a 7A builder in Austin has proven.

If you have any specific questions you can PM me and I will attempt to answer them for you.

Going this route is definitely not for everyone and there are times when I wish I had just put a Lycoming on it and started flying it four years ago or so; but hopefully next summer it will be able to at least make some noise and maybe even take flight by the Fall...TBD of course!

Blue Skies

Doug Lomheim
OK City, OK
9A / 13B / FWF / Canopy
 
Rotary RV

Two friends built absolutely beautiful RV-8's with Mazda rotaries. They flew them to Vans (think both of them) where the factory guys put the Van's (does the ' go before or after the s?) -8 and a rotary powered -8 thru careful flight comparisons devised by Ken Krueger. The rotary powered plane(?s) climbed and cruised faster and IIRC were slightly less fuel efficient. Vans felt the rotaries put out over 200 hp (memory?). They were also extremely noisy. These planes had really fine paint jobs. Later one crashed in a Filbert orchard due to some sort of electrical failure - not a core engine problem. Unfortunately the pilot was seriously injured. Will try to find the RVator reference. The rotary sounds like a super aircraft engine once all cooling and support systems details are worked out. What a shame that gorgeous airplane was lost and the builder/pilot injured due to non-redundant wiring.
 
One nice benefit to the rotaries... This was true in the cars, not sure if it holds for the newer engines running in airplanes or not. If you lose oil pressure, a rotary will keep running. It will happily run without oil (or with minimal oil) and get you to your destination as it overhears. If it quits, or if you shut it down, that's it. It won't run again.

But it's a little better than a Lycoming in this regard... A Lyc will only run until it seizes... The rotary won't.
 
Rotary Myths

I was on the ACRE (AirCraft Rotary Engine list run by the cantankerously brilliant Paul Lamar for years. That was a great education on aircraft installs. I also have rebuilt and modified a few with my own hands.

Weight Myth:

I think that most, and likely all Mazda rotary installations are heavier by 30-60 pounds over the Lycomings. People tend to look at the raw weights and forget about coolant, reduction drives, etc.

Running without Oil Myth:

I also want to say that it is a myth that they will keep running without oil, this is not true at all. If you spring an oil leak at full power, your rotary will seize in short order. The cast iron rotors are oil cooled, and they overheat, expand, and then seize against the side housings. A fellow on ACRE had this happen to him due to rubber hose and worm clamp fittings on his oil cooler. (I don't know what he was thinking there, they use SS hoses with threaded fittings on the factory built cars...) Maybe he didn't realize they run much higher oil pressure... Thankfully he and the plane were fine. He was very proud of the fact that he was able to call his girlfriend to drive over with a trailer so he could remove the plane before any news crews could get a picture of it.

I think this one keeps coming up because a Mazda rotary WILL keep running without coolant. Your power will be reduced, and your engine will be toast, but it will keep running until you shut it off, well actually after, because it will be so hot that shutting off the ignition will not stop it from running. :)

Delicate Engine Myth:

They are not delicate, just particular. ;)

Low Power Myth:

I don't know of any current Mazda rotary aircraft installation with a decent port job. Mazda has these engines very choked down for emission reasons. I don't have clue why these guys use stock porting on an airplane, it makes no sense to me; it has no negative effect on reliability. I took a bone stock 160 HP 13B and did a sloppily hand-dremeled port job on it, and it was an incredible difference. I had a otherwise stock 2nd RX-7 that would go a GPS verified 158 MPH! With a peripheral port 13B you can get 240 HP at 6000 RPM, 300 HP at 7000 RPM.

Fuel Consumption Myth:

Mazda rotaries run great LOP, and set up properly will burn the same per HP as a Lycoming. In a car this is not the case, they have poor BSFC at low power levels.

Okay, I'm done. :eek:

Well, one other thought:

I think a Mazda rotary is bit heavy for a two place RV, but a mildly boosted (3 lbs) 13B on an RV-10 could be perfect. And it would weigh less, be cheaper, and have more power than the 540.


Hans
 
nucleus said:
Low Power Myth:

I don't know of any current Mazda rotary aircraft installation with a decent port job. Mazda has these engines very choked down for emission reasons. I don't have clue why these guys use stock porting on an airplane, it makes no sense to me; it has no negative effect on reliability. I took a bone stock 160 HP 13B and did a sloppily hand-dremeled port job on it, and it was an incredible difference. I had a otherwise stock 2nd RX-7 that would go a GPS verified 158 MPH! With a peripheral port 13B you can get 240 HP at 6000 RPM, 300 HP at 7000 RPM.
Click to expand...

I've dynoed my share of Wankels and never seen one produce these power levels at these rpms. They will certainly do these numbers but at about 2000 more rpms.
 
Rotaries

You know how memory tricks you -- thinking overnight I now believe those were RV-8A's. One had a P-40 like toothy smile on the cowl. Due to flooding in our house and reconstruction efforts am unable to get at old RVators, so can't give details. Maybe Vans could give you the issue. I still think the Mazda is one of the most attractive alternate powerplants. Anybody know if the 2nd of those 2 RV-8A's is still flying?
 
Rotary RV

Googled and found it! The article is in the 2005 RVator, 2nd issue that year. The title is "The Tiger and The Spitfire Come to Oregon - Rotary vs. Lycoming. Still can't get to my issue - can somebody find this one?
 
Bill Dicus said:
I still think the Mazda is one of the most attractive alternate powerplants.
Click to expand...

I don't know about that - I'll put my vote on a 2-stroke turbodiesel for that title. From a pure physics and package size point of view, this is perfect for aircraft. Unfortunately, it just doesn't exist yet as a viable product.

Now, if you want to talk about REALITY and not VAPORWARE, then yeah, probably the Mazda.

I would love to be able to hang the Deltahawk engine on my bird, but reality is that it just ain't gonna happen.
 
RV w/13B weight, power levels, etc.

With attention to detail in the weight department it is possible to bring in the total FWF weight on par with an O-320. Doing that would require using inconel vs. thick wall stainless steel for the exhaust system which adds to the cost quite a bit; etc, etc,.

Also as Ross stated, it's pretty much impossible to get 240 hp out of a two rotor at 6,000 rpm. A turbo would be required to pull off that feat or adding a third rotor (20B) should get you there. From what I have read over the years, a "ported" 13B with the high compression rotors should be able to deliver an honest 100 hp per rotor; assuming intake and exhaust systems are tweaked correctly as well.

One fun thing about the rotary experience over the past 14 years of being around it, is that I've gotten to meet quite a few retired engineers who are totally sold on the concept. Low parts count, simplicity, and the "potential" to keep the weight in line with Lycomings is very appealing to an engineering mind set...

Doug Lomheim
9A / 13B / slider frame bending today!
 
rv6ejguy said:
I've dynoed my share of Wankels and never seen one produce these power levels at these rpms. They will certainly do these numbers but at about 2000 more rpms.
Click to expand...

You have been dynoing Peripheral Port Wankels Ross?

Here is a link that shows some dyno curves for PP Mazda Wankels. Money quote:

"We demonstrated 240 HP at 6500 RPM on the dyno using two inch OD runners 24 inches long on a 13B 2nd gen engine and with a Weber carburetor no less"

This was on an untuned setup btw.

Hans
 
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nucleus said:
You have been dynoing Peripheral Port Wankels Ross?

Here is a link that shows some dyno curves for PP Mazda Wankels. Money quote:

"We demonstrated 240 HP at 6500 RPM on the dyno using two inch OD runners 24 inches long on a 13B 2nd gen engine and with a Weber carburetor no less"

This was on an untuned setup btw.

Hans
Click to expand...

I believe the factory Mazda race data which is actual but on a highly tuned, virtually unmuffled race engine with a sophisticated variable geometry intake system.

Sorry, I don't buy much of what Paul Lamar has to say. 6500 rpm is not 6000 rpm so even if his figures were real, that equates to about 222 hp at 6000 and we do see figures of around 190-210 corrected hp at that rpm on various street ported and PP engines respectively depending on induction and exhaust.

Believe what you want but 110-120 dB engines won't make you friends at the airport. With suitable mufflers in place, most PP engines will be closer to the 200-210 hp mark at 6000 rpm- and that will be very adequate in an RV as has already been shown.:)
 
Rotary Exhaust Note...

"Believe what you want but 110-120 dB engines won't make you friends at the airport..."
__________________

Ross Farnham, Calgary, Alberta


The exhaust note of an unmuffled 13B is something I really have no desire to be around, and I find it akin to running fingernails down the proverbial chalkboard! Having heard numerous 13B's over the years with mufflers of various construction types, I found it amazing how quiet it was possible to make a Renesis engine sound! An RV-7A builder in Austin TX has a crazy quiet installation and he kept all the bits a pieces under the cowling vs. placing a muffler under the fuselage. The vast majority of the sound sounds like prop noise on his installation! Since I live on a private airpark I can see a Renesis in my future at some point if for no other than for that one!
 
If one hasn?t looked into rotaries for the last ten years, I hope they will at least take time to read the Oct? issue of Sport Aviation. Some of the problems from over a decade ago have been successfully addressed.

According to the article, a good Mazda-based firewall-forward installation all-up will weigh between 325-350 lbs which they say is about the same as a Lycoming 360, just depends on configuration. It says it will also make 180-230 hp or more, burning close to the same amount of fuel.

Many advantages, a few are costs. Firewall-forward it says you?re looking at far less than $10,000. New experimental Lycomings firewall forward are what? $30-$35,000? Rebuilds for all major parts will amount to about $500.00 for the rotary.

Main disadvantages are figuring out how to cool the rotaries with radiators, but speed and airflow in a plane is to their advantage here, although a lot more thought has to be put into it. Others have noted the exhaust noise. Don?t know if Powersport has successfully solved this problem, I?ve never heard one, but it said that they make an incredibly quite Inconel system which were developed by RV flyers Jim Clark and Jerry Gustafson.

Tracy Crook and his rotary powered RV-4 won the 2003 Sun 100 at 209 mph and that was with his old 13B RX-7 engine. He?s updated to the Renesis )RX-8) and speeds are 217+. As an added bonus, Renesis parts are plentiful and roughly about half of that for the RX-7?s.

The article says many have flown over 500 hours of rotary time, some having more than 2,000.

After reading the article I looked up more info on these engines. They have come a long way, and there seems to be quite a bit of people able to help on RV's. I?ll probably still opt for the Lycoming, only because I have my hands full learning how to build my first RV, but if I had more time, and had the right neighbor, such as Crook, Atkins, Clark or Gustafson, or the like, I think I would go this route. If I did, I think I would also have an extra $25k in my pocket too.
 
It's the Rotary/Subie options that's making me rethink the 9 choice since a 7/8 would allow a heavier engine install than the O320...although there is probably enough margin in the standard W&B to not have an issue in the 9...move the battery back, etc.

Bob
 
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