Powersport Aviation

I met with Jim and Jerry from Napa, CA at OSH last week to talk about their installations. Also had several email corespondence with Ray at Powersport in the last couple of days, and I have to say that I am impressed with the engine and installation-especially as a firewall forward kit. Prices are comparable to the Lycosaur/Lyclone prices when new or remanufactured prices are considered.

They need a few orders to get things going again, but are on the path to producing the engine kit again. Currently producing and shipping PSRU's and exhaust systems.

I am definately considering this an option for my -7 with a rotary. I will still put a fixed pitch prop on the front as the electric MT C/S is mucho dinero $$$, and I just can't see adding that much to the price of the firewall forward. Plus, the performance numbers don't add up to be much better than the FP.

Anybody have any thoughts on these guys?
Did anyone else meet them at OSH? I know Ray was there, but no booth.

I'm pretty much up on all alternative engine packages out there. I think these guys have by far the best engineered rotary on around. Real engineering and testing went into the redrive. Machining and installation details look top notch and very well thought out. I like their proper solution to rad layout and cooling with the new cowling, which looks mean and they are the only ones out there to have the guts/ confidence to fly to Van's to test head to head against Van's demonstrators. That says a lot. I think these guys have done it right and the price looks reasonable for what you are getting.

Powersport RV8s

I enjoyed looking at these planes at Oshkosh. The two builders were very generous with their time.

You mentioned performance numbers on the variable vs. constant speed prop. Were these tests run on an auto conversion?

I would reconsider the fixed pitch prop. The range of RPMs you can fly with a typical auto conversion really cries out for a constant speed prop.

rv6ejguy said:

I'm pretty much up on all alternative engine packages out there. I think these guys have by far the best engineered rotary on around. Real engineering and testing went into the redrive. Machining and installation details look top notch and very well thought out. I like their proper solution to rad layout and cooling with the new cowling, which looks mean and they are the only ones out there to have the guts/ confidence to fly to Van's to test head to head against Van's demonstrators. That says a lot. I think these guys have done it right and the price looks reasonable for what you are getting.

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These guys have a very nice engine package. They have some money problems right now. Their cooling solution is clunky and somewhat marginal. A very large rad relying on pressuring the cowl. Not as good a system as direct ducting. I have spoken to Steven Weinzerl the engineer who did the PSRU, a very intelligent guy. Powersport builds a dry sump that was sold through Mazda Speed, another nice unit though pricy. The engine and PSRU is very nice. Perhaps an escrow account for buyer protection? They need to do a better job on the rad, otherwise top notch.
Bill Jepson

rv8ch said:

I enjoyed looking at these planes at Oshkosh. The two builders were very generous with their time.

You mentioned performance numbers on the variable vs. constant speed prop. Were these tests run on an auto conversion?

I would reconsider the fixed pitch prop. The range of RPMs you can fly with a typical auto conversion really cries out for a constant speed prop.

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I would agree that a variable pitch or C/S prop is required for most atmo auto conversions otherwise takeoff and climb performance would be kinda poor. You just don't make much power at 4K on a Wankel in the ground roll.

The rad layout on these involves a big aluminum rad mounted just off the firewall. There is a top cowling off photo here: http://groups.yahoo.com/group/E-SubieForum/

Not elegant but I bet ground and climb cooling is no problem. Agreed that there are probably lower drag solutions but nobody is flying one ...yet.

RVator Article on the powersport Wankel

Here is the RVator article on the two nice RV8's tested against Van's demo planes. (Why the 200hp was slower than the 180hp RV I don't know, no explanation was offered in the article, except I would guess it is tired from several thousand Demo flights.) Click to enlarge, click again to enlarge more



I think the rotary is one of the best alternatives, and the Powersport is one of the nicest looking engine kits I have ever seen, regardless of power plant. I am in the Lycoming camp, but appreciate the rotary. My family had a Mazda RX3 when I was in High School. Later I bought a tired old Mazda RX2 beater to abuse, drove it, sold it for parts. The RV3 suffered the dreaded overheat that melted case seals they where known for in the early days. They have improved greatly since than, but you still don't want to overheat them.

A hydraulic prop on the rotary would be great. I am not a fan of $10,000 electric MT prop. The noise and especially the fuel burn will be harder to solve. The fuel burn is due to the inherent basic design of the Wankel combustion chamber. The use of a turbo charger can improve the fuel burn (MPG) if you fly real high (mid-hi teens) all the time (ie, O2 sucking), but that is not how I fly or use my RV, which is 80% local or short X-C. A turbo is not for me. As far as noise I read a forum post that the turbo cuts some of the noise a bit, but I still don't think stealth is the rotary long suit.

A turn off for me is the use of oil. You have to fill an oil injector every gas fill-up or add it to the gas, like a two stroke. Oil consumption on a healthy Lyc is about 1qt in every 16 hours flight, so you might get by with breaking out the oil once between oil changes.

The last is turn off is cost. If you go with a Powersport it will cost more than say a $19,000 new 180hp Lyc clone. All the alternative engine kits cost more than a Lycoming. However Tracy Crook @ RWS offers bits and pieces for a do-it-your-self rotary. With Tracy's parts and a used Mazda engine and home-grown rebuild, you can get under say 13K. It has been done many times by builders with fairly good results, but don't think it is as refined as the Powersport in looks or performance. However add an expensive MT prop you are at or more than a Lycoming. No offense to Tracy but the Powersport is a better set-up, but it cost way more. With Tracy you are left to make, design, fab and install many details, but there is nothing wrong with that. The powersport is more of a fully engineered package.

Still it cost more than a Lycoming clone and is only a few MPH faster at greater fuel burn (up to 35% more fuel burn!). With national 100LL around $3.23 that could be significant over time. So cheap rebuild or not, it is something to consider. A Lyc will give you say 2000 hours of flying before rebuild. That is how many years?

Powersport has been around forever developing their engine and reduction drive. It was started by the late RV'er Everett Hatch, who pioneered the rotary engine in RV's. Unfortunately he was killed in an untimely RV3 crash, possibly from pilot incapacitation. The work he started is continued by Powersport. I would love to see them succeed. So all you pony up and buy those power sports.

Cheers George

George,

Thanks so much for the very nice write up! That's exactly what I was looking for-information, not an argument! Very much appreciated! I do have the RVator article, and read it with great anticipation and interest. I met Tracy at OSH this year, and a local friend of mine is going that route. That's probably the route I'll take as well, because it will ultimately come down to money. But, if something changes in the next year or two financially, Powersport will hear me knocking!

I am planning on using a fixed pitch prop on either engine. I have read several articles that INDICATE that the performance gain is not that great with the C/S prop-maybe I'm wrong, but a Catto three blade should give me some really great numbers. I know that take off performance will suffer a little, and climbing at 2000fpm vs. 2500fpm isn't that big of a deal for me. $10-12k for the electric prop is ridiculous.

I talked with Dave Atkins at OSH, and his oil use is no where near that high. Probably varies with each installation/engine condition/type of oil injection used. Fuel burn...well I can't argue there, but I will be able to use 93 octane as well, so there's some cost saving opportunities there. 100LL at my airport is $3.76/gal!!!!

Thanks again!

The oil issue is no big deal in the Wankel. Just add your oil prior to fueling. No different than using TCP in a Sube or Lycoming. Just don't forget! (Add to preflight checklist). It's a pretty good Lyc that only burns 1 qt. every 16 hours. The ones I fly are more in the 4-8 hours per qt. The Wankels I have worked use nowhere near this amount of oil.

As discussed previously, Crook and others are reporting fuel flows pretty close to Lycs when aggressively leaned using his ECUs. Crook appears to be a straight shooter but it would be best to verify these claims with a head to head at Van's under controlled conditions.

Using auto fuel can save a lot of $ if it's available at the airport or if you are willing to haul it. I can't be bothered myself but for others, it's no big deal.

I'm not keen on a $10,000 prop either but a fixed pitch prop on most auto conversions results in a serious degradation of takeoff and to a lesser degree, climb performance. You just don't develop much thrust with a Wankel at 4000 rpm with the blades mostly stalled on takeoff. With a high enough power to weight ratio, this may be acceptable to some however. This is the reality of working with the smaller engine displacements of most auto engines.

Noise is a BIG issue with the Wankel and much research is ongoing on muffler designs to take the acoustical and temperature punishments dished out by these engines. This is a weight, space and maintenance consideration. Turbos quiet these engines WAY down and solve the fixed pitch dilema but at higher cost, weight, complexity.

I had always heard and read that these are turning more like 6000 rpm for takeoff, turning the FP prop at around 2600 rpm. Takeoff performance shouldn't suffer at that point, correct?

On one of the Rotary lists this morning, Tracy said he averaged 6 gph for his entire trip to OSH and back! 17.1 hours and 101 gallons of fuel. Pretty good if you ask me!

Not possible to have 6000 on takeoff with a fixed pitch prop and have much less than 7000-8000 in cruise flight. To have 6000 in cruise, I'd guess that you'd be closer to 4000-4500 rpm static on the ground at WOT.

Problem with most auto engines including rotaries is that power peaks are usually developed at 5000-7500 rpm. You can't develop rated power at 1000-3500 rpm below power peak plus a FP prop is partially stalled at low airspeeds leading to poor acceleration and thrust. With a Lyc, power and torque peaks occur at almost the same rpm and are very flat so a FP prop works pretty well on a light aircraft like an RV.

Yes, it does seem that Tracy is getting pretty decent fuel flows compared to the Powersport guys.

Come on

rv6ejguy said:

The oil issue is no big deal in the Wankel. Just add your oil prior to fueling. No different than using TCP in a Sube or Lycoming. Just don't forget! (Add to preflight checklist). It's a pretty good Lyc that only burns 1 qt. every 16 hours. The ones I fly are more in the 4-8 hours per qt. The Wankels I have worked use nowhere near this amount of oil.

As discussed previously, Crook and others are reporting fuel flows pretty close to Lycs when aggressively leaned using his ECUs. Crook appears to be a straight shooter but it would be best to verify these claims with a head to head at Van's under controlled conditions.

Click to expand...

TCP? Why would I use that? I never have used that and I was a flight instructor in a fleet of 35 plus aircraft, most with Lycoming engines. Lead fowling in a typical (higher compression) O-320/360 today is a non-issue, as long as the pilot leans the engine properly on the ground.

Yes 16 qts an hour, what are you saying I am lying?

robertahegy said:

I put 8 quarts in with a new filter on my 0-360. Half a quart (or more) goes in the filter leaving 7.5 (or less) in the sump. I go 25 hrs without having to add. I use about 1 qt in 25. Very little gets on the belly.

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OneTwoSierra said:

I've put 8 qts in the last 2 oil changes in my 0-320 with oil screen only. The oil drops to 7.5 quarts rather quickly (4 or 5 hours) and then slowly burns another 1/2 qt over the next 20 hours. I'm going to stop wasting that quart and go with 7 and see what she does. I appreciate all the discussion on this topic.

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If your Lycoming is burning a qt every 4-8 hrs , you have worn valve guides, rings or both? My twin with 2150hrs used less than 1qt in 8 hrs, which is after 2150 hours. My RV-4 used about 16-18qts/hr. With the new cylinder materials, Nickel-Carbide and thru hardened jugs, oil use has been lowered even more (read above).

Adding oil or any additive is a pain in the backside and you have to do it every time you add gas with the Rotary. I asked Tracy Crook about this. I forgot the oil use but it was significant, like a 3/4qt per fill up, which is about 1qt every 4 hours. Rotary uses more oil than a Lycoming, because it needs oil in the fuel to lube the seals, like a two-stroke engine! I mean it is not big deal and you don't have to be defensive and throw some useless Lycoming number out like a qt in 4 hrs. I mean it is just a fact and you don't have to attack a Lycoming to justify it. It is just the way it is. Every time you fill up you have to break out the bottle of oil to put in the tank. Lycoming might go several fill ups before getting the bottle out. Some are going oil change to oil change with out adding oil to their Lyc. Yes you check it, but that is little effort compared to adding oil. If it is not big deal to you, than great, Mo-power-to-ya. I hate it. I flew Cessna Citations Jets. When uplifting Jet-A I had to add the anti-ice called Prist to the fuel in a little spray-can.

This thread was started to discuss the Powersport, not attack Lycoming with exaggerated claims. When faced with facts like the RVator article I hear excuses and attacks. I can't understand why you have to justify the fact a rotary is thirsty, loud and uses oil. If you have data that is well documented, than just present that with out all the pot shots and defensive attitude. If you want a Wankel get one, but be realistic, it has limitations. Don't be so insecure you feel you must justify your choice in engine by tearing down the prime engine used in most aircraft. Don't justify the limitations of the Wankel, embrace them. There is a reason Mazda is the only one making a rotary engine car. They burn more gas. That fuel burn is justified in a hot sports car and may be an airplane. FACE THE FACTS:

THE ROTARY ENGINE RV-8 IN A FLY OFF AGIANST A LYCOMING POWERED RV-8 BURNED 34% MORE FUEL WITH AN ADVANTAGE OF 3-4 MPH.

I think that is pretty good. However when Tracy wants to race my RV-7 180HP Lyc, 4into1, dual EI, NASA/Lopresti/SamJames style cowl. Bring it. I know power sport engines are modified to make more power than the near Stock 13B Tracy uses. Again go slow, leaned out=Better fuel burn; GO fast, rich=High fuel burn. Apples and Apples. In the end the only way to get efficency is fly high, which applies to the Lycoming or any engine. This is as much or more from aerodynamics of flight and lift/drag relation of the airframe as it has to do anything with the engine.

Lets have a Cross country side by side fly off between Tracy's RV-4 and a RV-4 with Lycoming. Than we can see who is burning more fuel. Even a Lycoming with fuel injection can run lean of peak and get real low fuel burn, at the expense of speed. Again, lets o this. ANY RV-4's pilots with a IO-320 out there want to do this? I say IO-320 because Tracy's RV-4 is as fast as a fast 160HP Lyc powered RV, however a IO360 would work to. Tracy raced in the 160hp class lastat Sun-in-fun but claims it makes 180hp?

Fuel burn? Facts, how fast was Tracy going in this super lean mode. I have flown my RV-4 to 17,500 and got fuel burn down below 5.25gal/hr and still had TAS of +165MPH (that was a O320 150HP Lyc). When you open up a Wankel (race mode) it will drink fuel at a higher rate. I like how you ignore the RVator article and divert the rhetoric to Tracy and his ECI can go into super lean mode. Look Apples and Apples. You want power you burn gas. Wankel will burn more than the equivalent piston Lycoming producing the same thrust. Deal with it. You can mitigate this weakness but you can't eliminate it. You want to dream of super efficient super Lean mode go ahead. Accept it or continue to be delusional. People don't fly "Super Lean". Tracy's own test on a new rotary engine produce eye watering fuel burns (17gal/hr) or something like that. Again the experts agree that the physics of combustion in a rotary engine has inherent inefficiencies. I know I am blaspheming on the alter of rotary, but it is true.

As far as noise, prove a turbo makes the rotary quite. Facts, numbers, test. I don't care I love engine noise, including a rotary. Again from the RVator:

DURING THE RV-8 FLY OFF THE ROTARY POWERED RV-8 GOT THE ATTENTION OF THE AIRPORT AUTHORITIES!

G

rv6ejguy said:

Not possible to have 6000 on takeoff with a fixed pitch prop and have much less than 7000-8000 in cruise flight. To have 6000 in cruise, I'd guess that you'd be closer to 4000-4500 rpm static on the ground at WOT.

Problem with most auto engines including rotaries is that power peaks are usually developed at 5000-7500 rpm. You can't develop rated power at 1000-3500 rpm below power peak plus a FP prop is partially stalled at low airspeeds leading to poor acceleration and thrust. With a Lyc, power and torque peaks occur at almost the same rpm and are very flat so a FP prop works pretty well on a light aircraft like an RV.

Yes, it does seem that Tracy is getting pretty decent fuel flows compared to the Powersport guys.

Click to expand...

6EJGuy,
Tracy is flying with a newer version of his PSRU with a 2.82:1 reduction ratio. Take off is at 75-7800 rpm and cruise about 4800. (I don't remember what his static RPM was.) Don't be as concerned with those high RPM numbers as the rotary doesn't suffer at higher R's as piston engines do. In fact Mazda did stress studies when preparing to build it's '91 LeMans winner and found that at 6000 RPM the net bearing load was zero. (due to various balance factors) Tracy is swinging a 79" prop if I remember correctly and on his first flight wasn't ready for the torque reaction and P factor when he firewalled the engine and almost ended up in the weeds to the left of the runway! The rotary does have a wide RPM range and I'm sure a C/S prop is the way to go. I like Tracy, but if you want to run a C/S Mistral's Psru may be the way to go for you. Expensive at around $6500 bucks, but comes equiped for driving a prop govenor and a second alternator. The unit is a purpose built planetary with a 2.82:1 reduction drive using spur gears designed for the power output. A great looking magnesium casting as well. I'm glad they will sell to experimental builders. Unless Tracy goes C/S I will use the Mistral unit on my RV-10.
As an aside, Mistral will also sell you a "engine forward" package with the PSRU, C/S prop, and governor at a "reduced" overall price. (I didn't ask) They have been very honest at promoting the rotary though and it's probably worth a look.
Bill Jepson

Hey George,

I hope those last couple of paragraph's weren't directed at me and my comments. I have never boasted about low fuel burn of a rotary. I know Tracy was running super lean, and I was just making mention of the low burn he achieved for that particular trip. I am not that concerned with fuel flow rates, and if my power comes at the expense of higher burn rates, so be it. I can accept that. There's no question whatsoever in my mind that the rotary is thirsty. I'm not going to use one in an effort to conserve fuel. And I will never attack lycomings, or the clones. I've said it before, and will say it again, they are great engines, and I have no problem with them. I've had two previously, and they were almost perfect in performance, and just about 100% dispatch reliable. If I ever go back to certified airplanes, a lycoming will power it again.

No hard feelings, man.

Fuel burn? Facts, how fast was Tracy going in this super lean mode. I have flown my RV-4 to 17,500 and got fuel burn down below 5.25gal/hr. When you open up a Wankel (race mode) it will drink fuel at a higher rate. I like how you ignore the RVator article and divert the rhetoric to Tracy says his ECI can go into super lean mode. Look Apples and Apples. You want power you burn gas. Wankel will bun more. You want supper efficient and you claim a super Lean mode is more efficient than another type of engine
Accept it or continue to be delusional. People don't fly "Super Lean". Tracy's own test on the new engine produce eye watering fuel burns. Again the experts agree that the physics of combustion in a rotary engine has inherent inefficiencies. I know I am blaspheme on the alter of rotary, but it is true.[/QUOTE]

George,
I will NOT insult LYC's, but you should know the the rotary using more fuel at the same MAX and CRUISE output is a MYTH not a fact. Early rotaries were truly gas hogs in around town driving in auto use. They had thermal reactors (read afterburners) to get the HC smog levels down. The use of FI and improved intakes and exhaust technology has provided a much more efficient engine. In '91 running the rotary powered prototype to a overall win at Le Mans Mazda finished with the MOST fuel remaining of all the prototypes! There are many factors which go into this, but the engine was shown to be at least as efficient as any of the pistons running. You are going to use a similar amount of fuel in the rotary to produce a given HP level as a Lyc will. As to the oil thing, THIS IS A NON ISSUE, if you don't want to add to the fuel tanks RUN THE STOCK SYSTEM. The oil consumed isn't even close to typical LYC oil consumption. This isn't an insult just a fact. Throughout rotary development the amount of oil injected has continually gone down, with the newest RX-8 engine using the least of all.
Bill Jepson

Hey Bill,

Those were the numbers I was referring to, but it seems like dragging names into threads can cause problems. Anyway, thanks for posting that. You are right about the high RPM contentness in the rotary.

What a lot of people don't realize (but many do) is that the rotary turning 6000 rpm is the rpm at the eccentric shaft. The rotors are only turning 2000 rpm. The e-shaft is a solid piece of balanced metal turing a very small radius. This has probably been posted here before, but I can't remember.

The Mistral is another outstanding package, and I am hot on that one too! There PSRU is the perfect solution, being able to use a hydraulic C/S prop. Pricey though, even more so than Powersport. Does anyone know if there FWF package comes with an engine mount?

I listened to the RV-8's fly at OSH, and didn't think they were obtrusive. Louder than a 180-200 horse lyc, yes, but I didn't think they were any louder than a 210, Bonanza, or Viking taking off. It's just a different sound to me, and it's pretty cool sounding, and I was right next to the runway at the approach end.

Maybe it's just me, but I think they sound good!

No sir, I am a happy camper

cjensen said:

Hey George,I hope those last couple of paragraph's weren't directed at me and my comments. No hard feelings, man.

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Oh no sir, I am laughing and appreciate your comments. I just have to keep Mr/ RV6EJGUY in line. All in good fun of course.

I would like to see more side-by-side fly-offs so we can cut thru the emotion of bull. I don't care what the out come is, and would love an alternative to come out head and shoulders above, but this is the real world. I would love the Subi, Rotary, Lycoming to go head to head and really get the facts. We have some data and I think most of the pros and cons are on the table with some noise and smoke clouds. I like to cut thru the noise and smoke.

Cheers George.

cjensen said:

Hey Bill,

Those were the numbers I was referring to, but it seems like dragging names into threads can cause problems. Anyway, thanks for posting that. You are right about the high RPM contentness in the rotary.

What a lot of people don't realize (but many do) is that the rotary turning 6000 rpm is the rpm at the eccentric shaft. The rotors are only turning 2000 rpm. The e-shaft is a solid piece of balanced metal turing a very small radius. This has probably been posted here before, but I can't remember.

The Mistral is another outstanding package, and I am hot on that one too! There PSRU is the perfect solution, being able to use a hydraulic C/S prop. Pricey though, even more so than Powersport. Does anyone know if there FWF package comes with an engine mount?

Click to expand...

Chad,
The Mistral rotary comes with a custom built rear cover that attaches to the standard Dynafocal mount. They will also supply mounts for a bed (Conti) style mount. Their prices are higher on everything as they are certifing the rotary, as opposed to just suppling parts. Certified engines are great, but they have their problems too, witness the extension of the Lyc cranckshaft recall to new 4 cylinders as well. ANY engine has pluses and minuses. I believe the rotary makes a excellent aircraft package. Powersport has a nice package, but it is not without flaw. Powersport has had money problems as well that have prevented a lot of additional product development, hope they can get their problems ironed out. Alternate engines are best used by those who have enough engineering expertise to contribute to the design process. If you have any doubt put in a standard aero engine. On the other hand developing your engine package can have the same rewards as building your own aircraft. You MAY produce something that works better than the standard. The converse is also true so always be sure to use the best possible parts and systems throughout. It's your tail on the line!
Bill Jepson

All internal combustion engines TARGET approximately the same air to fuel mixture, ideally somewhere around 14:1. Lean mixtures generate a lot more more heat than rich ones do, particuarly so at high power levels; the actual mixture used ends up being a compromise. Water cooled engines should be able to run slightly leaner than air cooled engines, because heat breaks down lubricating fluids and we have to regulate piston/head temps.

From what Ive gathered, the rotaries (and probably most of the auto conversion fuel-injected motors run safely/leaner compared to carburated motors- because their mixture is automatically optpimised by sensors and computers, not by "feel" as most of the old-school Lycs, etc.

However, the conventional aircraft engines run at about 1/2 the automotive conversions' rpm, which likely burns less volume than an a smaller automotive motor running at a faster speed. It is a matter of large displacement x rpm/2 x fuel concentration with the Lycs vs smaller displacement x rpm x concentration with the rotary. The rotaries fire on each rotation of the crankshaft, the 4-cycle engines on every other rotation. Im guessing the displacement of the Lycs is the 320/360 cu/in listed in the engine series??? The rotaries have 1.3 liter displacement.

All in all, actual fuel burn rates are pretty close from what Ive seen reported, with the older rotaries slightly higher, and less efficient, due to the rounded constantly-changing shape of their combustion chamber. The newer Mazda Renesis designs have a better design that looks to be more efficient at low rpms than the older motors were. There is also the issue of the geared reduction units- there are always efficiency losses thru a tranny and propeller.

The sound issue is also a push- noise generation depends on the individual exhaust systems being compared. Tracy's muffled engine is quieter than most of the Lycs on the flight line. With straight pipes, the rotaries are probably worse- exhaust is hotter (more energy to dissipate) and has a higher pitch (more like a snarl than a roar).

The oil burn rate in the rotary is much less than the 2-cycle motor we all love/hate-- not a big deal. The oil loss rate is unnoticable when the burned oil is pulled from the crankcase. I feel the best solution is to use a separate oil tank to provide 2-clcyle oil to the rotor lubricating pump, and use a synthetic oil in the crankcase. Mixing oil with fuel is another common racing alternative that works well, generaly requiring a few ounces of 2-cycle oil per 5 gallons fuel added to the tanks. I dont like the potential of detonation, fuel/oil separation under extreme conditions, or problems with the oil mixing completely with the fuel in the tanks under that scenario.

Oil and Gas

Rotary10-RV said:

There are many factors that go into this, but the engine was shown to be at least as efficient as any of the pistons running. You are going to use a similar amount of fuel in the rotary to produce a given HP level as a Lyc will. As to the oil thing, THIS IS A NON-ISSUE, if you don't want to add to the fuel tanks RUN THE STOCK SYSTEM. The oil consumed isn't even close to typical LYC oil consumption. This isn't an insult just a fact. Throughout rotary development the amount of oil injected has continually gone down, with the newest RX-8 engine using the least of all.
Bill Jepson

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Ok that is good. I would like to see that. I am not saying in some operating condition the Wankel can approach the efficency of a piston engine, but lest have some side-by-side fly offs. There it is in black and white in the RVator. OK. So now we should have Tracy do a fly off using his equipment.

As far as oil, I agree it is a moot point with Av gas costing an avg of $3.23 a gal. However I got it from the horse?s mouth, Tracy and the oil burn, or should say use, was high. I don't recall but it was the better part of a qt to each tank of gas. Really no lie, 16-18 hours per qt is not an unrealistic amount for a Lycoming. So what is the real world oil use of a Rotary engine?

Cheers George

George, George, take it easy. No one is calling you a liar. I am just putting forth with what I see with club and rental Lycs, some low, some high time. My friend's O-360 RV is pretty good, he says a qt. in about 12 hours. A used to fly a Tiger a lot with an O-360. Had 400 hours on it after a complete overhaul, Broken in by the school owner an A&P. Used 1 qt. every 4-6 hours like clockwork. Ran fine, good compression and leakdown and went right to 2000 hours again. To say that a Wankel uses a lot of oil, what do you mean by a lot? They hold about 6 qts. and I have many friends and customers with Wankels over the years. You could easily drive 5-10,000 miles before adding a qt. of oil. I think Mazda spec'd something like 1.5cc in 3 minutes at 3000 rpm through the metering valve. This works out to over 30 hours per qt. My Sube goes 35 hours before I add. Many Eggenfellner Subes add no oil between changes at 40-50 hours- big deal- it's no real burden to add some oil.

gmcjetpilot said:

TCP? Why would I use that? I never have used that and I was a flight instructor in a fleet of 35 plus aircraft with Lycoming engines. Lead fowling in a typical O-320/360 is a non-issue as long as the pilot leans the engine properly on the ground.

I merely mentioned that adding 2 stroke oil to your fuel is no harder than adding TCP say to my tanks. I was not saying that you need to run TCP in a Lyc. Is it more trouble than adding nothing? Of course. A lot of trouble? No. You add what you need. If you are adding Prist to jet fuel, you do it. If you add TCP to my 100LL in my Sube, I do it because it is important.

Adding oil or any additive is a pain in the backside and you have to do it every time. I asked Tracy Crook about this and the oil use is more than a Lycoming, because it is needed to lube the seals. I mean is just a fact and you don't have to attack a Lycoming to justify it. It is just the way it is. Every time you fill up you have to break to bottle out and put in the tank. If it is not big deal to you, than great, Mo-power-to-ya. I hate it. I flew Cessna Citations Jets. When I had to add Jet-A I had to add the anti-ice to the fuel.


Yes 16 qts an hour, what are you saying I am lying?


If you are burning 4-8 qts you have worn valve guides, rings or both?
My twin with 2150hrs used less than 1qt in 8 hrs, which is after 2150 hours.
My RV-4 used about 16-18qts/hr.

The tread was started to discuss the Powersport, not attack Lycoming with exaggerated claims. When faced with facts like the RVator article I hear excuses. I can't understand why you have to justify the fact a rotary is thirsty, loud and uses oil. If you have data that is well documented, than just present that with out all the pot shots, which indicates a defensive attitude. If you want a Wankel get one, but be realistic, it has limitations.

Fuel burn? Facts, how fast was Tracy going in this super lean mode. I have flown my RV-4 to 17,500 and got fuel burn down below 5.25gal/hr. When you open up a Wankel (race mode) it will drink fuel at a higher rate. I like how you ignore the RVator article and divert the rhetoric to Tracy says his ECI can go into super lean mode. Look Apples and Apples. You want power you burn gas. Wankel will bun more. You want supper efficient and you claim a super Lean mode is more efficient than another type of engine
Accept it or continue to be delusional. People don't fly "Super Lean". Tracy's own test on the new engine produce eye watering fuel burns. Again the experts agree that the physics of combustion in a rotary engine has inherent inefficiencies. I know I am blaspheme on the alter of rotary, but it is true.

Click to expand...

I'm not ignoring the fine article you were so kind to post. I'm simply saying that others in the Wankel field do not agree. I think Tracy was mentioning around 7 gal/hr. at 160-165 knots TAS. Tracy has apparently experimented running in cruise at AFRs in the 17 to 1 range with no ill effects. We can cruise auto engines at 17 to 1 and some lean burn engines at 22 to 1 because they have better chambers and fuel disribution than aircraft engines. Funny how you are quick to quote Tracy for high oil consumption and then disbelieve his fuel flows. We do not know what AFRs the Powersport guys are running.

Inherently the combustion process in a Wankel is relatively inefficient due to high surface to volume ratio of the combustion chamber however there are many offsetting factors, no valves or valvetrains, less moving parts and lower frictional losses than piston engines. Shaft hp is highly influenced by frictional hp losses in all engines. It's what get to the prop that counts on the whole package efficiency.

You can make hp at quite lean mixtures in liquid cooled engines. Look at the turbo engines in Cart and F1 of years past when fuel limits were brought in. Honda was able to still make over 680hp with very lean mixtures. Auto engines are different in many ways than air cooled aircraft engines. Even in turboed aircraft engines, best SFCs are obtained at LOP with some extra MAP added.

You are right in saying one thing here. The Powersport aircraft tested here burned a lot more fuel for the mission than the Lycs did. They also outperformed them despite higher weight. The other thing the test proved is that they were damn loud. Fine. These two guys obviously like them despite these drawbacks. The state of the art is progressing every day on Wankel conversions and Tracy Crook and Mistral are the two at the leading edges of current development. I hope that Powersport is able to get back to a position again to offer their conversions.

100%

rv6ejguy said:

The state of the art is progressing every day on Wankel conversions and Tracy Crook and Mistral are the two at the leading edges of current development. I hope that Powersport is able to get back to a position again to offer their conversions.

Click to expand...

I agree. I hope both these parties and power sport do well so they can continue to improve their products while making a little money. The thing I like about the RVator fly off is the Black & White facts and no opinion. The noise thing is subjective. Also I am all for using the Lycoming bench mark to shoot for or shoot at. Really that speaks well for the Otto cycle that has been around for +150 years. The Wankel is 60 years old and still around. Many other ideas have come and gone. The new hyd prop Mistral reduction drive sounds great. Yes $6,500 is a lot of green. Bottom line for me, for any alternative engine to buy its way into my cowl, is it has to exceed the bang for the buck formula:

Final price of installation + Final weight of installation + Effort to install + Reliability (redundancy and system issues) + operational cost + efficency + overall performance + general satisfaction + (want to be differnt) = BINGO

Depending on how much weight you put on one factor over the other depends on you choice. I think the power sport has hit a home run in some areas that where strike outs before. Other areas not so much, but they are still swinging, no fault of their own. They spent a decade of development to bring this to market. For me in the above equation BINGO = Lycoming. The (want to be differnt) factor is a big ZERO factor. I did have a funny haircut in college for a while, but in my aircraft design I don't mind conforming. However as soon as an engine (any engine) can fill the boxes to my liking, BINGO might equal a rotary, but not quite yet.

MORE SIDE BY SIDE FLY OFFS BETWEEN LYC POWERED RV's AND ALTERNATIVE ENGINE RV's. The cafe foundation would be perfect to do these test with instrument packages on the aircraft.

Cheers George

WOW! My head is spinning from this thread! I love it! I am going to have to re-read this to get it all to sink in.

George,

You are so right on the CAFE foundation. I can't believe the EAA won't endorse them!

I will gladly agree to a fly-off when I'm done, but that's gonna take some time. There will probably be several ahead of me, so hopefully this can happen sooner than later.

combustion chamber efficiency

George&Guy
On thing that is overlooked in the combustion chamber efficiency arguement is that the rotary is a prime candidate for rotor coating (cermet or ceramic) to seriously improve chamber efficiency. The over-cooling provided by the large or rather long and high surface area combustion chamber is improved by coatings available now. I'll ask Tracy on the FlyRotary forum if his new engine uses the rotor coatings to improve efficiency. The other thing is that Tracy won the race to OSH in his RV-4 twice (in his weight class) so he must be doing something right!
Bill Jepson

I agree that the Wankel will only show more potential as it is developed and I think things like coatings may see the fuel flows dropped as TE is improved. The surface has just been scatched so far. Tracy just ignores all this stuff yaked about in these forums and flies the thing, wins races with it and lets the results speak for themselves as he improves his products. I hope Tracy or another Wankel guy will step up to the plate and do a fly off at Van's. The Egg guys say they will soon too with a Sube. Both will prove interesting.

When I get my -10 done and tested, I plan a trip to Aurora to show its stuff and I'll do another article in Kitplanes too if they are interested with a head to head against an IO-540 RV10.

May the Wankels continue to hmmmmmm while the rest of us go boing, boing.

cjensen said:

WOW! My head is spinning from this thread! I love it! I am going to have to re-read this to get it all to sink in.

George,

You are so right on the CAFE foundation. I can't believe the EAA won't endorse them!

I will gladly agree to a fly-off when I'm done, but that's gonna take some time. There will probably be several ahead of me, so hopefully this can happen sooner than later.

Click to expand...

Chad,
A quick side note off topic. We (my EAA chapter) had C. J. Stevens who was the chief test pilot for CAFE for years at our last meeting. He said that the rift between the EAA and CAFE came when the editor at Sport Aviation said that they wouldn't print any articles anymore that couldn't be understood by an average student pilot! He said that the CAFE articles were too technical. Talk about dumbing down, it really torques me off. The EAA is more interested in warbirds, antiques, and certified than the original EXPERIMENTIAL base. There are several alternate organizations trying to start up catering to homebuilders.
Bill Jepson

Ha! Dumbing down...that's great, simple way to put it! Just wait 'til more and more of the LSA airplanes get going. EAA will be (is) ALL OVER those certified birds. I support the LSA movement, but EAA will get farther and farther away from their beginnings with this.

Dumbing-down is dumb

Besides reducing the value for those of us that want more technical content, the biggest problem with dumbing-down the articles is that it hurts those they're trying to target. How are new and technically illiterate pilots supposed to learn if they're not exposed to detailed information about how aircraft fly and perform?

kcameron said:

Besides reducing the value for those of us that want more technical content, the biggest problem with dumbing-down the articles is that it hurts those they're trying to target. How are new and technically illiterate pilots supposed to learn if they're not exposed to detailed information about how aircraft fly and perform?

Click to expand...

Kevin,
There seems to be more misinformation around the more technical the subject becomes. I couldn't agree more with you about the "dumbed down" articles hurting those searching for knowledge. This thread about Powersport as example. Many reading here wouldn't know this is the second time around for Powersport, it was started in the NW by Everett Hatch a real mechanical wizard and had great promise. Everett was killed in a non-expermental aircraft accident. A great loss to the alternative engine world. The new Powersport bought the company later and is a well meaning company but is suffering financially. (I got that info from a inside source.) I REALLY WANT THEM TO PULL THROUGH THIS AND SUCCEED. The previous to prevent them from thinking I'm trash talking about them. Powersport HAS really done their homework on the conversion. I have only one knock which is they aren't providing for constant speed props on their PSRU. That and the somewhat high initial cost stopped me. I really hope we can provide some well designed conversions to test against Lyc based aircraft of the same type for proof-of-concept.
Bill Jepson

BTW are you the "TDC" Kevin Cameron? If so I would love to talk rotary with you off-line if possible. WRJ

quote from a earlier Cobra post

"However, the conventional aircraft engines run at about 1/2 the automotive conversions' rpm, which likely burns less volume than an a smaller automotive motor running at a faster speed. It is a matter of large displacement x rpm/2 x fuel concentration with the Lycs vs smaller displacement x rpm x concentration with the rotary. The rotaries fire on each rotation of the crankshaft, the 4-cycle engines on every other rotation. Im guessing the displacement of the Lycs is the 320/360 cu/in listed in the engine series??? The rotaries have 1.3 liter displacement.

All in all, actual fuel burn rates are pretty close from what Ive seen reported, with the older rotaries slightly higher, and less efficient, due to the rounded constantly-changing shape of their combustion chamber. The newer Mazda Renesis designs have a better design that looks to be more efficient at low rpms than the older motors were. There is also the issue of the geared reduction units- there are always efficiency losses thru a tranny and propeller."

I wanted to comment about the assumptions in the prior startement.
First; Slower engine RPM doesn't automatically result in less fuel consumption! The factors are HP generated, load moved/lifted/stopped, frictional losses, and actual combustion efficiency. A 250cc road motorcycle might get 75-100 mpg while turning 4-6000 RPM. While a Lyc IO-540 isn't designed to turn that speed and would probably grenade at 5K! Not a knock they are just different. Rotarys have no stop-start motion and the ability to balance exactly for lower losses. For most engines operating somewhere near the torque peak reguardless of RPM usually results in best milage.
Second; The rotary runs well considerably leaner than most pistons can. Tracy and Mistral are both reporting that they can run lean-of-peak for most if not all operations. Mistral is reporting compareable numbers (or better) comparing their rotary IN OPERATION IN A PIPER ARROW to a Lycoming powered equivilent in side-by-side conditions. Tracy (who claims personal cheapness) leans before take off!
Bill Jepson

cjensen said:

Hey Bill,

Those were the numbers I was referring to, but it seems like dragging names into threads can cause problems. Anyway, thanks for posting that. You are right about the high RPM contentness in the rotary.

What a lot of people don't realize (but many do) is that the rotary turning 6000 rpm is the rpm at the eccentric shaft. The rotors are only turning 2000 rpm. The e-shaft is a solid piece of balanced metal turing a very small radius. This has probably been posted here before, but I can't remember.

The Mistral is another outstanding package, and I am hot on that one too! There PSRU is the perfect solution, being able to use a hydraulic C/S prop. Pricey though, even more so than Powersport. Does anyone know if there FWF package comes with an engine mount?

Click to expand...

Chad, I went back to this post to mention that several people have been working on taking power off the rotor for a built in 3:1 RPM reduction!
Bill Jepson

Rotary10-RV said:

Chad, I went back to this post to mention that several people have been working on taking power off the rotor for a built in 3:1 RPM reduction!
Bill Jepson

Click to expand...

I really enjoy mechanism design and love to see "new" components.
This connection to the rotor will be impressive to me for sure!
The rotor orbits at the E shaft rotational speed and rotates at one third the E shaft speed.
The rotor rotationally accelerates and decelerates significantly on its path around the housing and I believe obtaining a connection to it that will result in a smooth rotational output for a propeller will be an interesting study.
-mike

mlw450802 said:

I really enjoy mechanism design and love to see "new" components.
This connection to the rotor will be impressive to me for sure!
The rotor orbits at the E shaft rotational speed and rotates at one third the E shaft speed.
The rotor rotationally accelerates and decelerates significantly on its path around the housing and I believe obtaining a connection to it that will result in a smooth rotational output for a propeller will be an interesting study.
-mike

Click to expand...

Mike the rotor doesn't accellerate and decellerate, it orbits a perfectly circular ORBIT. The rotor rotates and orbits which causes the variable area for the otto-cycle. The only accelleration and decelleration is with the overall engine speed. It is really amazing and hard to wrap your head around. Felix had several 5 chamber designs and one similar to the current one in which the chamber spun and e-shaft was fixed like a old radial! I believe that it was an NSU engineer that helped Wankel "finish" the rotary into the configuration we have today.
Bill Jepson

Rotary10-RV said:

Mike the rotor doesn't accellerate and decellerate, it orbits a perfectly circular ORBIT. The rotor rotates and orbits which causes the variable area for the otto-cycle. The only accelleration and decelleration is with the overall engine speed. It is really amazing and hard to wrap your head around. Felix had several 5 chamber designs and one similar to the current one in which the chamber spun and e-shaft was fixed like a old radial! I believe that it was an NSU engineer that helped Wankel "finish" the rotary into the configuration we have today.
Bill Jepson

Click to expand...

I think maybe I have a reference frame issue here. The rotor certainly orbits in a circular path and if your reference is from the center of that orbit, its velocity is constant and therefore its acceleration is zero. But, if your reference is the housing, then certainly there is an acceleration component.

Use an automobile tire as an easy to understand example of my confusion. From the axle or spindle reference frame, there is no acceleration of the tire at constant vehicle speed but, from the road's perspective, the tire stops at the contact patch and then accelerates to twice vehicle speed at the top and back to zero again as it completes one revolution.

I go back to my earlier post, it will be interesting to me to see a mechanism that can take the wankel rotor's rotational velocity for power output while somehow ignoring its orbiting velocity (and accelerations from my reference frame)

Not a naysayer, just an interested bystander.

Rotary10-
I actually agree with you on this. My assumptions were based on looking at the motor's volumetric flow- that a certain amount of fuel/air physically flows thru the engine at a given speed, defined mostly by the "pistons" displacement, the number of times it refills (rpm), and the fuel/air mixture which were assumed to be constants for comparison sake (not in the real world where mechanical systems are imperfect).

Looking back in retrospect, I realise that I overlooked two things. 1.) while it is true that the rotary fires on each rotation of the rotor, it only fires on every third rotation of the crankshaft, and crankshaft rotation is what is normally measured. Therefore the correct formula should use the factor rpm/3, not "rpm" alone for the rotary.

2.) I failed to consder the pressure driving the fuel/air mix into the intake manifold- basically assumed everything happens at ambient pressure/temp with no restrictions to flow. That is incorrect as you indicated, except at full throttle.

I agree with your assessment the the engine is most efficient at the torque peak- the technical term (I believe) is the maximum abdiabatic efficiency point, where the combustion chamber pressure peaks and the engine uses the every bit of air that it can muster. With turbocharging, the rpm range at that point where we have to tune most carefully, because it is the point where detonation control is the most critical, and I believe, where the heat generation peaks as well.

I dont know about the lean burn part of your comment, but it makes sense to me. The large surface area of the piston/combustion chamber should be less prone to detonation; heat generaton and (related) detonation is really what determines how lean you can run safely.

cobra said:

I agree with your assessment the the engine is most efficient at the torque peak- the technical term (I believe) is the maximum abdiabatic efficiency point, where the combustion chamber pressure peaks and the engine uses the every bit of air that it can muster. With turbocharging, the rpm range at that point where we have to tune most carefully, because it is the point where detonation control is the most critical, and I believe, where the heat generation peaks as well.

I dont know about the lean burn part of your comment, but it makes sense to me. The large surface area of the piston/combustion chamber should be less prone to detonation; heat generaton and (related) detonation is really what determines how lean you can run safely.

Click to expand...

Torque peak actually occurs at peak volumetric efficiency and peak chamber pressure. On either side of this rpm, VE and CP are lower. Max heat generation is at peak hp rpm where the maximum amount of heat is being liberated per unit time. Detonation is most likely to happen at or near peak torque however this is dependent on ignition advance to a large degree. The Wankel does have better anti-detonation qualities than most piston engines due to it's high surface to volume ratio chamber but it can certainly still detonate. John Slade's turbo 13B has demonstrated operation up to 46 inches MAP on 87 octane auto gas which is quite impressive.

Recent testing has revealed than the mixture strength has far less to do with detonation tendecies than previously thought or commonly believed. In cruise conditions, the lean limit is usually defined by mixture distribution between chambers, mixture homogeny, spark energy available and mixture turbulence. Engines which have these items optimised are capable of running LOP smoothly and efficiently.

It don't matter

All this info is good, and may be technically and theoretically correct, how fast the rotor turns, the speed of the combustion flame front or the angle of the dangle, and it means nothing, the proof is in the number's (real world performance, side-by-side against a Lycoming powered RV).

Right now the only reasonable side-by-side numbers is from the RVator. And the only big negative was the fuel burn. Now bring in a representative, Real World Solution 13B or other new rotary engine company (all I think use Mazda cores) to flight test against a Lycoming.

When someone says I burned X on a X-C flight, that is great info, but with out a long list of supporting data to back up the MPG it means nothing. My 150HP Lyc RV-4 from Seattle To Phoenix was doing 265 MPH at 6.5 GAL an hour! (pause, wait) and could have made it direct (1100 sm) with no stops (wait, pause). True, but missing some info. I was at 12,500' and had a 70kt tail wind. I also would have burned 28 gal with 32 gals tanks (31 usable), so technically it would have been possible (but not wise). I passed my normal fuel stop (Redding/Red Bluff, Ca) and landed in Bishop CA in 3 hours (about 724sm). Obviously with out the fact I had 70kts of tail wind the data is not usable. (If I would have had larger tanks by 8 gals I would have went non-stop direct to PHX.) True story, not many times you get tail winds like this.

BTW, a Lycoming can also run LEAN of peak (if fuel injected).

Cheers George

BTW, a Lycoming can also run LEAN of peak (if fuel injected).

Cheers George[/QUOTE]

George, What we were making a point about is that the rotary can run lean of peak more safely than a piston engine. Any piston engine, Lycs included. The Piper Turbo Meridian was using lean of peak operation to show good fuel numbers and they are now facing a class action suit for failure to make TBO. I am not getting on Piper's case here as I believe most pilots are not well trained on LOP operation. That is I believe LOP failures are pilot induced most of the time. Rotaries are less prone to problem and have proven pretty bulletproof LOP in NA operation. Turbo is also good LOP with the need to preform normal detonation prevention measures like retard at high boost, like any ICE.
Bill Jepson

cobra said:

...Looking back in retrospect, I realise that I overlooked two things. 1.) while it is true that the rotary fires on each rotation of the rotor, it only fires on every third rotation of the crankshaft, and crankshaft rotation is what is normally measured. Therefore the correct formula should use the factor rpm/3, not "rpm" alone for the rotary.

Click to expand...

Here I may be showing my ignorance again on this engine but it looks to me like there are three combustion events per rotor revolution (one for each of the three faces) and therefor one combustion event per crank revolution per rotor.
On the 13B that means two combustion events per crankshaft revolution, one every 180 degrees of crank (e shaft) rotation.

-Mike

i agree with the LOP operation bill. we deal a lot of malibu/mirages (meridian is the turboprop ), and we see a whole bunch of the mirages not making times because of poor LOP procedures. i have time in both malibu's and mirages, and i still need instruction on how to operate them properly. i just don't feel comfortable running LOP if i'm not absolutely certain that i'm doing it correctly. there's been some printed material circulated recently that states that LOP operation of the TSIO-540 is not recommended anymore. too many people looking for lawsuits, i guess.

anyway, the rotary is superb at LOP operations.

what was this thread about??...the rotary, Powersport...oh yeah.

this has been a great discussion.