Photos of a sectioned Pobjoy Niagra

[Stealth Pilot[_2_]]

I have posted a large archive to alt.binaries.pictures.aviation with
scans of 12 photos taken of a sectioned pobjoy niagra 90hp engine.

this is an engine worthy of a model engineering reproduction or even a
homebuilt engine in full size for homebuilt aircraft.

from memory the engine as photographed is 21 1/2 inches in diameter.
in one of the photos is a dressmakers tape measure graduated in
centimetres.

other dimensions....
these were taken off the pobjoy R 75hp engine on display in the
shuttleworth trust.

the splined prop shaft appears to be inch diameter. the rear spline on
this shaft that the reduction herringbone gear is positioned on is
40mm diameter. between the end of the inch spline and the 40mm spline
the tapered shaft section is 48mm long.

in the front centre of the motor is a square boss with rounded
corners. the boss is 49mm across. the hole in the centre is 36.5mm
diameter.

the reduction gearbox from front to back is about 150mm.
the width of the rear part of the casting is 60mm.

the four head fins are 120mm diameter.
the cylinder is 100mm from the underside of the head to the aluminium
face of the engine casting.
the bolt down cylinder flange is 9mm thick.

veedubber I've emailed a copy of the scans for your blog.

Stealth Pilot

[Veeduber[_2_]]

On Jun 8, 8:00*am, Stealth Pilot >
wrote:

>
> veedubber I've emailed a copy of the scans for your blog.
>------------------------------------------------------------------------------------------------

Dear Stealth,

Thank you very much. I will keep an eye on the mail box. It is
nearly 300 feet from the house and has a history of losing things.

Should you be interested, the Weak Force Press ( http://www.weakforcepress.com
) in Huntsville, Alabama has a copy of the Operation, Installation,
and Maintenance manual of the Pobjoy "R" Type Aero-Engine on a CD.
They will be happy to send you a copy for about $16 USD (more in Oz
dollarettes, of course :-)

As a point of interest to all, under the Maintenance Schedule are
listed:
Check tappet clearances and (apply)graphite grease (to ) pushrod
ends

Every 50 hours:
Clean & adjust Sparking Plugs.
Clean & adjust Magneto Contact Breaker Points
Clean & adjust Carburetter Jets & Float Chamber by removing
Jets and flushing with petrol
Remove the Rocker caps and using the Grease Gun provided:
Fill the Rockers with High Melting Point Grease

Every 100 to 150 hours:
Top Overhaul the Engine. (!!)
After 300 to 450 hours:
Remove the engine from the airframe and have it completely
overhauled
------------------------------------------------------------------------------------

There are some other equally interesting items that make the manual
something of a trip into the past. From the cam timing it's obvious
the engine was never designed to drive a prop directly, but was
intended to be used with a two-bladed metal prop turning 1400 rpm at
an engine speed of 3000 rpm.

-R.S.Hoover