How many people are interested in a GOOD safe psru for the rotary?

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
129
Location
NW Oregon
Sorry, I don't have any magic for you on single rotors Wankels. They would be pretty heavy for the power produced. Several reasons:

Really big counterweights are necessary;
Firing order vibration would be huge, requiring one or both of, torsional pendulums and very long stroke "soft" isolation system.

With only one rotor, the entire eccentric mass of the shaft and rotor has to be balanced with counter weights. With two or more rotors, the primary (up and down) imbalance is taken care of by having the eccentrics evenly distributed, and the counterweights only have to balance the pitching moments. The more rotors, the smaller this whole effect is and less counterweight size needed.

The firing frequency on a single rotor is one per rev and really strong. Torsional pendulums would be useful, but they would have to be really big to tame that low a firing order. A soft system would require pretty low spring rates, which means a lot of travel and volume occupied by the spring system. You might need both...

In the end, Wankel single rotor engines will be heavier and more complex than two rotor engines of the same power.

Billski
Bill and group,
All our work has been with 2 or more rotors. To make a LSA single rotor I beleve it could be done with a light weight rotor. Either machined steel or cast titainum. That would allow counterweights of about 1/3 the mass. The torque pulses would still present some problems but no worse than a big single piston. Smoother actually since it isn't reciprocating. Just a thought. The pendrlum style dampers could be built into the counterweight and flywheel, (which is also a counterweight), to make a compact package.
The other Bill
 
Last edited:

brucec995

New Member
Joined
Oct 17, 2016
Messages
3
Location
South Eastern NSW, Australia.
Sorry, I don't have any magic for you on single rotors Wankels. They would be pretty heavy for the power produced. Several reasons:

Really big counterweights are necessary;
Firing order vibration would be huge, requiring one or both of, torsional pendulums and very long stroke "soft" isolation system.

With only one rotor, the entire eccentric mass of the shaft and rotor has to be balanced with counter weights. With two or more rotors, the primary (up and down) imbalance is taken care of by having the eccentrics evenly distributed, and the counterweights only have to balance the pitching moments. The more rotors, the smaller this whole effect is and less counterweight size needed.

The firing frequency on a single rotor is one per rev and really strong. Torsional pendulums would be useful, but they would have to be really big to tame that low a firing order. A soft system would require pretty low spring rates, which means a lot of travel and volume occupied by the spring system. You might need both...

In the end, Wankel single rotor engines will be heavier and more complex than two rotor engines of the same power.

Billski
Doesn't a single rotor wankel fire 3 times per crankshaft revolution?
 

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
129
Location
NW Oregon
No, the rotor rotates at 1/3 E-Shaft speed.
Bill
For aircraft I always thought that it would be great if you could take the drive right off one of the rotors. it would be perfect as a prop drive. Couldn't think of a reasonable way to do it. Of course if we can figure a way to do that the single rotor LSA rotary would be awesome. Hijacked my own thread!

Bill
 

don january

Well-Known Member
Log Member
Joined
Feb 10, 2015
Messages
2,778
Location
Midwest
Bill. I have a chance to buy a 13b off of a aircraft without a PSRU. I think it would be a neat power plant for a stock KR-2 if the weight can be brought down to the very minimum. But I think we are still looking at around 280 lb. with cooling Ect. I'd love to see a single or more rotor engines used in todays home built's. I'd kick down 3 or 4 grand $ if it fit my mission.
 

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
129
Location
NW Oregon
Don,
I am working with a gear manufacturer right now. He has made custom gearsets for the Reno Merlins. When we have some pricing information I will be forwarding estimates to the group.
 

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
129
Location
NW Oregon
Any chance you will have a prop governor option?
Possible, but more likely with a second generation. The drive has already been run with an MT electrical operation prop without TV issues. It would be easier to drive from the engine end, and most of the regular CS props are very heavy

Bill
 

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
129
Location
NW Oregon
Charlie,
Trying to finalize the price and methods for the ring gears. We are looking at ratios of 2.6:1 and 2.8:1. 2.8 is the preferred ratio right now. We like to keep our RPMs down so either would work, but the 2.8 ratio allows more headroom. The fact that the north central portion of Oregon has been covered in ice has made things difficult. I will post updates. We have the dyno engine hung on the plane now. Trying to complete that. Muffler is being scoped after the dyno running to be sure of it's durability. Don't want anything coming adrift!
Bill
 

wsimpso1

Super Moderator
Staff member
Log Member
Joined
Oct 18, 2003
Messages
6,518
Location
Saline Michigan
It has been five months since we heard ANYTHING about this project. Has install been finished. Report on flight performance and fuel burn? Torsional vibe survey? Come one, we want to know about this...
 

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
129
Location
NW Oregon
Billski,
Still at it. Regular job has interfered as I was living in a hotel on site while we completed a large Cleaning machine. We compressed design and delivery of a machine that would normally take 5 months to 9 weeks. This was all in work and precluded any work on the gearbox/2rotor install. Will be at the gear cutters tomorrow and will post updates.
Bill
 

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
129
Location
NW Oregon
Ross,
I am planning to check to see if we can do 2.2 or 2.4:1 on the same centers as the 2.7 would work for the Subarus too.
Bill
 

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
129
Location
NW Oregon
Billski,
Sadly my regular work won't allow a OSH visit this year. The reduction drive is a desire and alternative engines a passion, but as so many have found there isn't a large enough market to make it an only business. I have the layout and modeling done, bearings ordered, and I'm working with the gear facility now. The guy I'm working with has done reductions for Reno Merlins and does beautiful work but he isn't fast. If you or others on HBA know of a reputable gear maker put me in touch! Always best to have several sources. I will not allow myself to be one of the many B.S. slingers, that have given alt-engines such a bad name. I intend to have a product ready for use. My foremost principle is to develop the product on my buck and present it ready to go. I want the answer to a buyers question, "When can I expect delivery?", to be, "As soon as your check clears."
Bill Jepson
 

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
129
Location
NW Oregon
Got the first set of bearings in. Should be up to the task. Not a commercial post the card is only included for sizing.
TIMKEN32017X-SMALL.jpg
Bill Jepson
 

Billrsv4

Well-Known Member
Joined
Sep 29, 2016
Messages
129
Location
NW Oregon
Charlie, I am completely ready to proceed, lacking only money for some of the machining. I am going to sell my RV-10 kit for the money to complete the gearbox/s first run. I plan to return to a kit AFTER I have running examples to sell to cover the cost of production. We have an RV-3 ready to fly soon. lots of finishing stuff that takes forever.
Bill
 
2
Top