Rotary engines

[John A]

This is interesting, rotary engines. https://youtu.be/DCt_G8j8Hfw

[oldbike54]

 Technically those are rotating radial engines .

 Dusty

[Roebling3]

A favorite airplane is the Depurdussin, racing monoplane. It had a twin row 14 cylinder air cooled engine and set stunning speed records, at the time. Late 20's iirc.
A replica @ 3/4? scale was built by the late owner/founder of Old Rhinebeck Aerodrome, Cole Palen, in Red Hook, NY. Great place to visit!
I believe his Depurdussin is still at 'Owls Head transportation Muse`, Owls Head, ME. Another great place to visit - year 'round.
BTW: The Depurdussin had very poor landing characteristics and no brakes. Palen hid disc brakes on his. It was still a handful.  R3~

[DougG]

Hi John,                                                                                                                   11-9-20

I read in a few places that HD engines began as two cylinders basically "cut" out of an eight cylinder radial aircraft engine on a common crank.  This gave them their iconic "potato - potato" loping idle.  I think the front wheel radial engine the article is describing in the motorcycle is a two-stroke.  The HD is a four stroke, of course.  But yup, a number of different geometries have been tried...each has its pros and cons.

Frankly, I'm partial to the "V the way it's meant to be". 

Be well, stay well,
DougG

[Testarossa]

The word rotary is is used specifically to distinguish Gnome and LeRhone derived and similar fixed crank engines from fixed case radial engines. Rosaries go all the way back to Samuel Langley and generally precede radicals. The purpose was to keep cylinders and heads cool at low airspeeds.

Typed this on my phone which has auto-complete, which I hate, but the result in this case is amusing enough to keep.

[Two Checks]

There is the proper term, "fixed crank".
But I think rosaries were firmly established many, many years before...


Harleys have a common crank, just like Guzzis and our cages.
But Harleys use a common crank pin with a knife and fork rod arrangement.

[Antietam Classic Cycle]

"Rosaries" and "Radicals" 

[oldbike54]

"Rosaries" and "Radicals" 

 When the radical priest came to get me released
 We was all on the cover of Newsweek

 Dusty
 

[Triple Jim]

The word rotary is is used specifically to distinguish LeRhone derived and similar fixed crank engines from fixed case radial engines. Rosaries go all the way back to Samuel Langley and generally precede radicals. The purpose was to keep cylinders and heads cool at low airspeeds.

Right.  I heard and read about rotary airplane engines years before "rotary" referred to Wankel engines.

[PhilB]

Hi John,                                                                                                                   11-9-20

I read in a few places that HD engines began as two cylinders basically "cut" out of an eight cylinder radial aircraft engine on a common crank.  This gave them their iconic "potato - potato" loping idle.  I think the front wheel radial engine the article is describing in the motorcycle is a two-stroke.  The HD is a four stroke, of course.  But yup, a number of different geometries have been tried...each has its pros and cons.

Frankly, I'm partial to the "V the way it's meant to be". 

Be well, stay well,
DougG

That's speculation at best, and has no basis in reality.  For one thing, actual radial engines always have an odd number of cylinders per bank.  There's no such thing as an 8-cylinder radial engine.

The 45 degree angle on Harleys is mainly because that was the widest they could get at the time, when adding a second cylinder, without redesigning their existing frame.

PhilB

[n3303j]

That's speculation at best, and has no basis in reality.  For one thing, actual radial engines always have an odd number of cylinders per bank.  There's no such thing as an 8-cylinder radial engine.
PhilB

Glen Curtis Aviation Museum
Hammondsport, NY

A really interesting museum in the middle of nowhere. Out on a ride with Son-in-law and spotted a C-46 in front of a building. Pulled in and ended up eating up most of a day examining their fine collection of aircraft, motorcycles, boats and bicycles. Worth the trip.

[Testarossa]

Ford actually called this an X-8 engine, and it never went into production because of production complexity and running problems never resolved. Instead Ford went for a flathead V8, which actually ran efficiently. Only two X-engines ever went into production as far as I know. Rolls Royce had an X-24 in 1939 made from two 60-degree water-cooled V-12 blocks, so it didn't have a round "radial" shape. It was heavier and less reliable than the more powerful V-12 Merlin. And there's a Russian tank engine I don't know anything about other than that it exists (or existed).

[n3303j]

X-8 preceeded this engine by about 25 years.

[Denis]

Technically those are rotating radial engines .

 Dusty

No, those are straight up rotary engines.

[oldbike54]

 Before everyone gets all worked up , Megola defined their engine as a radial , which was what had stuck in my head all of these years . Carry on .

 Dusty

[DougG]

Hi All,                                                                                                                                                          11-10-20

            As I said, "I read in a few places that HD engines began as two cylinders basically "cut" out of an eight cylinder radial aircraft engine on a common crank."


"But don't take that to mean radials are extinct -- oh, no. If you want to see 25 percent of a radial in action, you need look no further than your local biker dive or Harley dealership: Harley Davidson's classic V-twin engine is essentially just two cylinders hacked off of an eight-cylinder radial. The V-twin's signature rumble is a result of its even cylinder count, which, you'll recall, doesn't work well with this engine design. This coincidence of origin should come as little surprise, since Harley rose to fame primarily by catering to returning World War I veterans who were already largely comfortable with the radial design."

"Influences of the radial design can be found in modern-day Harley-Davidson V-twin motorcycle engines, however. With the two piston rods attaching to the crankshaft on a single rod journal, the Harley-Davidson air-cooled engine operates with many of the same principal designs as the radial engine."

"No, The 45-degree Harley Davidson V-Twin is not an incomplete radial.  But, in a reply to one of my answers about the Harley Davidson, Quora Writer Bosley Plourde explained Harley’s V-Twin to me. He reasoned that, as the only 45-degree engine that can be balanced is a V-16, HARLEYS SHOULD BE CONSIDERED V-16s WITH 14 MISSING CYLINDERS!"

        There are several other quotes with footnotes, but the discussion continues and the earth continues to spin, unperturbed by these differences of fact and opinion.

Be well,
stay well,
DougG

P.S.  Bosley Plourde?  Say that three times fast...now that's a name that sounds like an idling Harley! 

[slowmover]

While looking up Wankel engines I found this. Norton Classic air-cooled twin-rotor motorcycle.

[huub]

a proper norton wankel
pretty hot exhaust gasses ( look at the 2 minutes point)
https://www.youtube.com/watch?v=j-1nKtxZ2Wk

[JJ]

While looking up Wankel engines I found this. Norton Classic air-cooled twin-rotor motorcycle.

Yes!!  The famous Norton Rotary!!  A few more photos I took in 2011 from a guy's collection...

[Tim Henry]

And don't forget Carlo Guzzi was an ww1 airplane mechanic the cylinder on the original single looks very much like a radial cylinder

[wymple]

a proper norton wankel
pretty hot exhaust gasses ( look at the 2 minutes point)
https://www.youtube.com/watch?v=j-1nKtxZ2Wk

I believe Mazda used a double walled exhaust for that heat.

[Testarossa]

X-8 preceeded this engine by about 25 years.

You're right. And when you think about the dynamics of an X8 it doesn't make much sense. The pistons don't move like a boxer engine -- the opposing pairs move with each other on the same crankpin. Even if the action is offset by pistons on the second crankpin, the rocking motions -- in all axes -- must be fierce.

Real radials have an odd number of cylinders so i na four-stroke cycle they fire evenly and sequentially --  1-3-5-7-2-4-6. And they have ring-shaped cams to greatly reduce the number of parts. In the 20s and 30s aircooled radials were the most dependable engines available for aircraft -- hence Lindbergh used a Wright Whirlwind.

[ohiorider]

A classic rotary like a Le Rhone has pistons, rods, and a crankshaft.  Yet it isn't a reciprocating engine.  Agree or disagree?

- the crank is bolted to the firewall of the airplane, therefore, it cannot turn.
- the cylinders rotate around the stationary crankshaft.
- the pistons rotate along with the cylinders.

Each piston rotates along with the cylinders, but they don't move up and down. 

I wanted to describe this, but the level of detail is more than my aged mind can distill.  Or more than I want to type.

BTW, another neat feature of the early rotary motors was the fact that they didn't require a flywheel ....... the rotating cylinders served that purpose.

Bob

[n3303j]

A classic rotary like a Le Rhone has pistons, rods, and a crankshaft.  Yet it isn't a reciprocating engine.  Agree or disagree?

- the crank is bolted to the firewall of the airplane, therefore, it cannot turn.
- the cylinders rotate around the stationary crankshaft.
- the pistons rotate along with the cylinders.

Each piston rotates along with the cylinders, but they don't move up and down. 

I wanted to describe this, but the level of detail is more than my aged mind can distill.  Or more than I want to type.

BTW, another neat feature of the early rotary motors was the fact that they didn't require a flywheel ....... the rotating cylinders served that purpose.

Bob

Pistons do move up and down in their cylinders. Just imagine you grabbed the crankshaft output of a running engine with a bad mount. The mount breaks and the engine spins around the now stationary crank. Only problem is supplying fuel and spark (not insurmountable).

[Chuck in Indiana]

For one thing, actual radial engines always have an odd number of cylinders per bank.

True, for the most part, but I have seen a few (in museums) with equal numbers of cylinders.

[ohiorider]

Pistons do move up and down in their cylinders. Just imagine you grabbed the crankshaft output of a running engine with a bad mount. The mount breaks and the engine spins around the now stationary crank. Only problem is supplying fuel and spark (not insurmountable).

The point I was making is that the pistons don't reciprocate.  Each piston and rod rotates around its individual stationary big end crank journal.  In essence, the cylinders slide up and down around the pistons.

[n3303j]

The point I was making is that the pistons don't reciprocate.  Each piston and rod rotates around its individual stationary big end crank journal.  In essence, the cylinders slide up and down around the pistons.

No movement relationships within the engine have changed. Pistons still move up and down in the bore.
Just propeller is mounted on the "wrong" part. 

[Testarossa]

"But don't take that to mean radials are extinct -- oh, no. If you want to see 25 percent of a radial in action, you need look no further than your local biker dive or Harley dealership: Harley Davidson's classic V-twin engine is essentially just two cylinders hacked off of an eight-cylinder radial. The V-twin's signature rumble is a result of its even cylinder count, which, you'll recall, doesn't work well with this engine design. This coincidence of origin should come as little surprise, since Harley rose to fame primarily by catering to returning World War I veterans who were already largely comfortable with the radial design."

This is complete bullsh*t. Origin of Harley twin in 1909 has nothing at all to do with radial engines, and there never was such a thing as an eight-cylinder radial. Radial engines didn't go into general production until a decade after the first Harley twin. https://www.rideapart.com/features/247758/the-birth-of-the-harley-davidson-v-twin/

Radials don't have Harley-style forked piston rods but attach the big ends to a single master rod, the only one that rides on the crank throw bearing. Radials do not have Harley-style camshafts, but two cam rings (except for Bristol sleeve-valve radials which were way weird).

The first radials were developed FROM MOTORCYCLE engines in Europe by Jacob Ellehammer in Denmark (1903) using three, then five Peugeot cylinders, but never went into production. Alessandro Anzani had a three-cylinder "fan" engine in 1905 for his own motorcycles. It went into small-series production for airplanes and was used by Louis Bleriot to cross the English Channel in 1909. It became a three-cylinder "inverted Y" radial engine. There were some water-cooled five-cylinder radials before WWI but none went into production. Mass production of five- and seven-cylinder air-cooled radials didn't start in earnest until 1920, in Britain and the US, especially after the US Navy demanded them for all its planes.

[Off @ 90]

Yes totally agree with Testarossa . Radial engine cylinders are always odd numbers per row. Another interesting anomaly with radials is  the elliptical motion of the the slave crank pins compared to the circular path of the master rod crank pin.
This small difference in piston moment is compensated  by a special contact breaker cam in the magneto . This is one reason radials have that offbeat exhaust note.

[ohiorider]

No movement relationships within the engine have changed. Pistons still move up and down in the bore.
Just propeller is mounted on the "wrong" part. 

Here ya go.

http://stonehengeairmuseum.org/1918-le-rhone-rotary-engine

extract:  ........ rotaries delivered power very smoothly because there are no reciprocating parts ........

http://www.animatedengines.com/gnome.html

extract:   ..... Balance
Note that the crankcase and cylinders revolve in one circle, while the pistons revolve in another, offset circle. Relative to the engine mounting point, there are no reciprocating parts. This means there’s no need for a heavy counterbalance.