enginehistory.org

[gryan]

Correspondents to Torque Meter discussed balancing and timing issues (valve and spark) pertaining to radial aircraft engines.

A great deal of effort was employed in this regard during the design and construction of the great radial engines. Several clever fixes and compensation schemes were realised to mitigate some of the problems introduced by the effects of the master and slave rod system.

In TM it was mentioned that a lot of work was spent on deriving "true motion" mechanisms to ensure all pistons underwent the same motion and had the same timing. This sounds very interesting. As a mechanical engineer I would like to know more about those schemes. I understand there were patents filed. Does anyone know the patent numbers or the names of the inventors? Who were the applicants and which companies were involved?

What were the mechanisms derived?

Any comments appreciated!

Regards

Gerald

PS Quoting patent numbers is a good way to compile a list of relevant data, as the patents are available to look up on the web freely.

If anyone is interested I'll post some links to some Patent Offices.

[kmccutcheon]

“True motion” schemes for radial engines fall into two broad categories: ones with slippers on each connecting rod big end, and ones with some sort of mechanism replacing the master rod.

The Le Rhone rotary is perhaps the best known example of the first type, although inventors continue to use this scheme even today. A couple of examples I quickly found in my collection of patents are:
2,040,465 – Roland Chilton, assigned to Reed Propeller Co.
2,146,530 – Roland Chilton, assigned to Wright Aeronautical Corporation

Salmson radials with the Canton-Unne mechanism is probably the best known of the second type. A copy of the Canton-Unne patent can be found at
http://www.enginehistory.org/Misc/GB190927672.pdf

Other examples include:
2,092,639 – Roland Chilton, assigned to Reed Propeller Co.
2,235486 – Charles Lawrance, assigned to Lawrance Research and Engineering.
2,256,094 – Bradford Lynch

Unfortunately, there is no patent classification for “true motion connecting rods.” US Current Classifications 74/580 and 123/54.2 abound with many such schemes. Lists of patents in these classifications can be developed from:
http://www.uspto.gov/go/classification/selectnumwithtitle.htm
_________________
Kimble D. McCutcheon

[gryan]

Kimble, thanks for your post.

I'll look up the patents you recommended.

The only example I knew of was the Nordberg. These were two stroke radials with a true motion linkage. They were used to generate electricity for aluminium smelting. The crankshafts were vertical. They had a single row (level?) of cylinders with an even number of the cylinders in the row. They were huge units (ship engine size).

As an aside; I have often thought the radial engine would make an ideal power unit for trucking (or marine) applications.

A radial can be located aft, or even ahead of a truck cab (aft is better). Access and mass distribution would be improved. Taking some load of the steering axle would be a good thing. Interesting the manufacturers insist on the in-line six and on some V-types.

When the Detroit Diesel people moved out of two-strokes (which were short and compact) and into the Series 60 four-stroke, access became much more difficult in many instances. I know technicians and mechanics who left the game rather than work on those super tall engines in tightly crowded engine spaces. A radial low & behind the cab would be an improvement.

As far as radials in marine use are concerned, here is a link:

http://www.yachtboutique.com/BugattiMarine/Engines.htm

Now where do these come from? I'm betting they're Russian.
For the power they are compact. I'd love to hear one of these running through open stacks!

They would have to be the new champions when it comes to cylinder count. Until now the largest number was the V-24 two-stroke Detroit Diesel 24V71 with twenty-four cylinders. That one did sound nice.

Regards


Gerald

[kmccutcheon]

[gryan]

And a version with more than 100 cylinders! Amazing.

Thanks for the patent numbers. I'll be chasing them up. Good mechanical engineering to read and think about.

Perhaps we should have a listing on the AEHS site for interesting patents. All that need be disclosed is the subject of the patent, the applicant (company), inventor and patent number. Patents are freely available on the web and once you have the patent number you can get whatever you want to look at.