enginehistory.org

[jkinney]

Can any AEHS members help answer the following questions regarding the Continental XR-794 sleeve valve engine?

What was the sleeve/port timing?

Who was responsible for the design? Two names that have been mentioned are C.F. Bachle or W.R. Angell.

Thanks in advance,
Jeremy Kinney
_________________
Dr. Jeremy R. Kinney
Curator, Aeronautics Division
National Air and Space Museum
Smithsonian Institution

[kmccutcheon]

Progress Report on Development of R-790 Single Sleeve Valve Engine and Preliminary report on E4-G Test, 4-9-34: L.P. Kalb signed Development narrative; C. F. Bachle signed Inspection After Failure of Master Rod report.

50-Hour Endurance Test of Continental R794S Single Cylinder Engine, 12-7-35: C. F. Bachle signed report, A. J Meyer approved.

Design Data, R-1740 Single Cylinder Sleeve valve Air Cooled Aircraft Engine, 10-1-36: Written by A. J. Meyer, Chief Research Engineer. Although this cylinder is different from the R-794, its valve timing is as follows:
Intake Opens 60 degrees early
Intake Closes 55 degrees late
Exhaust Opens 80 degrees early
Exhaust Closes 60 degrees late

Numerous Endurance and Performance test reports on the R-1740 dating from 3-4-37 through 5-3-39 are reported by C. F. Bachle, Research Test Engineer and approved by N. N. Tilley, Chief Engineer.

Endurance Test of Continental R-1740 Single Sleeve Valve Engine, 1-25-40 is reported by E. A. Hulbert, Project Engineer and approved by: Reported by R. R Thibodeau, Project Test Engineer, C. F. Bachle, Assistant Chief Engineer; and J. W. Kinnucan, Chief Engineer.

Bachle, Meyer, Kinnucan, Hulbert all had sleeve valves patents, as did Ralph N. Du Bois, Edward T. Vincent. Of these, only Andre Meyer has the number and variety of patents that would lead me to think he may have been heavily involved in the R-794. See particularly US Patent 1984537.

While this does not answer the exact question that you asked, I hope that it may give you some leads.
_________________
Kimble D. McCutcheon

[jkinney]

Thanks, Kim!
_________________
Dr. Jeremy R. Kinney
Curator, Aeronautics Division
National Air and Space Museum
Smithsonian Institution

[tmcdaid]

Out of curiosity, is that somewhat typical timing for a sleeve-valve engine? The exhaust duration of 340 degrees seems huge, especially for a relatively low-RPM engine.

[kmccutcheon]

[mbrandon]

I spent some time checking the numbers given for the valve timing on both engines and here is what I came up with as far as duration: the difference is +70 exh and +10 int between the Continental and the Bristol. Does that bring it any closer to being reasonable ? I hope I have interpreted the discussion accurately ?

Continental Engine
___________________

exh duration
80 bbdc opens at end of power stroke
180 exh stroke
60 atdc closes beginning of intake stroke
--------------
= 320 degrees exhaust duration

int duration
60 btdc opens at end of exhaust stroke
180 int stroke
55 abdc closes beginning of compression stroke
----------------
= 295 degrees intake duration

Bristol Engine
______________
Exh duration
55 bbdc opens at end of power stroke
180 exh stroke
15 atdc closes beginning of intake stroke
-----------
= 250 degrees Exhaust duration

Int duration
50 btdc opens at end of exhaust stroke
180 int stroke
55 abdc closes beginning of compression stroke
------------
= 285 degrees Intake duration

Mike Brandon

[tmcdaid]

Sorry for the math error; my question was posted late at night. Nonetheless, for a poppet-valve engine 320 degrees would be tremendously long opening duration. Kimble's comment about the piston having an effect on port area is probably part of the answer and the rest of it probably has to do with the geometry of the ports and the opening and closing process -- it may be that a significant chunk of that duration is spent with a small effective open area.

At my meager level of expertise, mostly with poppet valve timing, I know the actual gas flow cross-sectional area is a big deal, so that a major benefit of overhead cams, lightweight valves, better spring materials, etc. is that the valve lift rates can be higher, allowing good flow with less opening duration (helping low-rpm performance and greater flexibility in car and truck engines).
_________________
Tim McDaid

[jwells]

Re the designer of the R-794 engine, it might have been Archie Niven. He was the Scottish engineer who travelled to the U.S. to be with Continental after the Argylls firm went broke.

He filed more than 70 patents in his time, most of them as assignor to Continental Motors.

US patent No 1,937,123 describes in detail a 9-cylinder sleeve-valve radial and contains a lot of detail about valve timing.

Jerry W.