# Considering a Rotary conversion, need help

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#### DLrocket89

##### Well-Known Member
Hi everyone,

I'm getting started building a Bearhawk. For those of you who don't know, it's a 4 place STOL / "utility" airplane. I'm intending on making use of the STOL part of that.

The design can use 160HP-260HP...the 260 is actually limited by weight, not thrust. I would like to get to the upper end of that spectrum while keeping the weight resonable. Hence, a rotary has possibilities.

My original plan was to buy a Conti O-470 or a Lyc O-540 near TBO. Figure proabbly $5K for the engine, I'd do the rebuild myself, but still looking at probably$15K in it by the end. For that kind of cash, why not get something that's even better, especially if I can learn a bunch in the process?

So, what's the current "state of the art" for converting rotaries? Most of the posts I've read have been from 2003-ish talking about the "new" Renesis engine, companies that no longer exist, etc. My main research so far has been into Real World Solutions, otherwise that's about it.

1) I'm interested in a turbo or a supercharger for better T/O performance, not necessarily high-altitude performance (though that would be a nice "bonus").
2) I'm fine with fabircating whatever requires a welder (exhaust, engine mount, etc).
3) I could design/machine/build a PSRU, but I doubt I could do better than someone who's been working on it for a few years. Who has the most "proven" design around?
4) I'm fine with building my own setup, but does anyone out there havea completed FWF for it?

#### Lucrum

##### Well-Known Member
Log Member
So, what's the current "state of the art" for converting rotaries? Most of the posts I've read have been from 2003-ish talking about the "new" Renesis engine, companies that no longer exist, etc. My main research so far has been into Real World Solutions, otherwise that's about it.

1) I'm interested in a turbo or a supercharger for better T/O performance, not necessarily high-altitude performance (though that would be a nice "bonus").
2) I'm fine with fabricating whatever requires a welder (exhaust, engine mount, etc).
3) I could design/machine/build a PSRU, but I doubt I could do better than someone who's been working on it for a few years. Who has the most "proven" design around?
4) I'm fine with building my own setup, but does anyone out there have a completed FWF for it?
A turbocharged two rotor will fit your requirements.
AFAIK RWS's PSRU gets good reviews, I have no personal experience.
I'm not aware of a FWF setup for an aircraft rotary. Maybe someone else does.

Here are some potential resources.
Tech and Performance - RX7Club.com
Aircraft Rotary-Best Practices
Atkins Rotary - Rx7 | Rx8 | Mazda | Rotary | Engine | Parts
AZRR - Arizona Rotary Rockets Store
Engine Parts
Pineapple Racing
Racing Beat - Mazda Rotary 1986-92
Rotary Response and Racing - Mazda RX7 Rotary parts and performance , RX-8
rotaryengine.com | Rotary Engine Specialists | Mazda Performance | RX7 Specialties
RX7 Store - Rotary performance parts and accessories

#### DLrocket89

##### Well-Known Member

That looks like a good listing of things. There was one place that had a 3" dial thing that would let you dial in variable boost...that would be fantastic...

So, I could probably talk to some engine builder and ask them to build me up a solid "core" of an engine, then buy all the stuff to convert it to airplane usage (PSRU, ignition, etc). Or, buy parts myself and build it.

*shrugs* could be fun.

anyone else?

#### Kristoffon

##### Well-Known Member
If your objective is to build an airplane, as opposed to endlessly tinkering with an engine, stick to stock configurarion as much as you can.

#### DLrocket89

##### Well-Known Member
If your objective is to build an airplane, as opposed to endlessly tinkering with an engine, stick to stock configurarion as much as you can.

Yeah, I hear you. I know a turnkey solution isn't available for less than \$30k...so, I'm going to get a builder to build the engine, buy a PSRU, buy an engine controller, etc etc...

Log Member

#### DLrocket89

##### Well-Known Member

I've seen his work, looks very nice. I like the whole idea of the rotary due to reliability and whatnot, try to get away from valves, cams, and other such things.

#### Mac790

##### Well-Known Member
I like the whole idea of the rotary due to reliability and whatnot, try to get away from valves, cams, and other such things.
Theoretically you are right, no valves no cams, etc, but you will have to use PSRU, which will be probably the weakest point in your installation. So theoretically old Lycozaurus might be more reliable, than Rotary with a PSRU. What PSRU are you thining about, seems that there are only two, Tracy and Powersport (r they still in business, did you cal them?)

Seb

#### Bob Mears

##### Well-Known Member
http://rotaryaviation.com/ Yes, Tracy is still in business. I chose his PSRU, Engine monitor, and engine controller, and have been very pleased with my purchase. There's several of these flying now and they are proving to be superb products.

#### Mac790

##### Well-Known Member
Bob, thanks for the answer but it seems I wasn't clear enough, when I said R they stil in business, I meant guys at Powersport, I know Tracy is still in the business, and I know that many people use his PSRU. What is your current status, any chance for test flight soon?

Seb

#### DLrocket89

##### Well-Known Member
Theoretically you are right, no valves no cams, etc, but you will have to use PSRU, which will be probably the weakest point in your installation. So theoretically old Lycozaurus might be more reliable, than Rotary with a PSRU. What PSRU are you thining about, seems that there are only two, Tracy and Powersport (r they still in business, did you cal them?)

Seb

Haven't called anyone yet. Seems like Tracy's PSRU seem to be holding up pretty well. Another thing is that I (at least to me) think it would be easier to inspect a PSRU as compared to say, a cam haft for spalling or something.

The PSRU is the only that that didn't go wrong for him!

#### DLrocket89

##### Well-Known Member
Given things I've read, here's where I'm at right now.

1) Have an engine built up by an engine builder who specializes in Mazda's for aviation use, planning on using a Renesis. Tracy Crook says on his website that he is in contact with engine builders who know what his systems need, and who can put one together for me. Sounds like the ticket.

2) Current plan is to use Tracy Crook's EC3, EM3, and RD-1C PSRU.

3) Order a turbo, making sure that it's capable of "continuous boost" (see the link above)

4) After looking through the NTSB accident database searching for "Mazda", one thing has come to light. Keep the gascolator cool! 2 of the 3 fatal accidents were caused by vaporlock....one of them was a cracked exhaust that blew right on the gascolator. Oops. Thinking I'm going to put a special air intake just to cool the gascolator. On that note, 4b) start making a list of all of the little "tweaks" I keep reading about.

Generally, I'm trying to tread in the footpaths of others before me. Before going too much further, I should probably order Tracy's book.

#### Lucrum

##### Well-Known Member
Log Member
Generally, I'm trying to tread in the footpaths of others before me. Before going too much further, I should probably order Tracy's book.
Sound wisdom.

#### danF

##### Member
See Aircraft Rotary Engine News Letter for discussion of rotary engines in aircraft. Lots of good info and answers to questions. Buy moderators book How To Cool Your Wankel for tips on oil and coolant system design.
I am looking to build a single rotor for LSA. The goal is 130hp and 140lbs firewall forward.

DanF

#### DLrocket89

##### Well-Known Member
I'm now plugged into the FlyRotary email forum, lots of good info there. Tracy Crook said that if I want 300HP, go triple rotor. What do people think of the trade between a NA 3 rotor or a turbo 2 rotor? Talking weight, HP, and reliability....

#### Lucrum

##### Well-Known Member
Log Member
I'm now plugged into the FlyRotary email forum, lots of good info there. Tracy Crook said that if I want 300HP, go triple rotor. What do people think of the trade between a NA 3 rotor or a turbo 2 rotor? Talking weight, HP, and reliability....
You can certainly get 300 HP from a turbo 13B and for less weight than a NA 20B. But, and I'm no expert, I think you'll be running it hard enough that engine life will be noticeably reduced.

#### DLrocket89

##### Well-Known Member
You can certainly get 300 HP from a turbo 13B and for less weight than a NA 20B. But, and I'm no expert, I think you'll be running it hard enough that engine life will be noticeably reduced.
turbo Renesis would be even better?

#### Lucrum

##### Well-Known Member
Log Member
turbo Renesis would be even better?
Probably, but I would still think, at 300 HP for a 2 rotor, it would still affect engine life more than most would prefer for our applications. Again I'm not saying it can't be done.

I've seen video of dyno testing where 300+ HP per rotor was acheived for short durations. Of course these are studded engines with water injection, turning 9000 RPM and using very high boost pressures. When you start pushing them that hard blowups become much more common at least based on what I've read.

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