Powersport Aviation

[rv6ejguy]

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.

Originally Posted by gmcjetpilot

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.

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 **** 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.

[gmcjetpilot]

Originally Posted by rv6ejguy

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.

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

[cjensen]

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.

[Rotary10-RV]

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

[rv6ejguy]

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.

[Rotary10-RV]

Originally Posted by cjensen

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.

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

[cjensen]

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.

[kcameron]

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?

[Rotary10-RV]

Originally Posted by kcameron

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?

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

[Rotary10-RV]

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