British poppet valve radials

[MiTasol]

Nice Pictures.

The American small radial market, like the Pobjoy was fading fast in the very late 30s.
There were some European small radials including a 40hp cylinder one around 1930.

But most of the aircraft owners in the 1920s-30s-40s were a pretty practical bunch of people and the Flat-4 and Flat-6 engines came to dominate the market and even pushed out the inline 4 and 6 cylinder engines. Using 5 cylinders when 4 would do or using 7 cylinders when 6 would do was not going to last very long.

The Popjoy used small cylinders running fast to get power and required a reduction gear for the propeller.
They may have been smooth and nice to fly behind but the cost to overhaul them would have been higher than the larger, slower turning radials and the flat fours offered lees vibration than the inline 4 cylinder engines.

A lot of the engines in the 1920s and 30s were going through major changes ever few years. A/S was building these in the 1920s
View attachment 663443
Note the much cruder cooling fins compared to the Tiger engine of the 1930s.
Also note that the 1920s Bristol Jupiter not only had the crude finning of it's time but used a different cylinder head from the later Mercury and Pegasus engines. The Jupiter used parallel valves and not the inclined valves of the later engines for an easy identification feature.

What people choose to fly behind for nostalgia maybe a lot different than what they would choose to fly behind in a "working" aircraft like an air taxi or doing flight instruction and racking up hundreds of hours a year.

If racking up hundreds of hours was your top requirement in the 30s then your only option was the AS Cheetah. They had 1200 hours between overhaul in the mid 30s and Pratts 985 and 1340 were still at 800 hours in the 60s. And if you want a smooth engine a radial always beats a flat engine in that period.

And also in the 30s Bristol Jupiter engines were made under licence in more countries than any Pratt or Wright (and probably than all Pratt and Wright engines combined) so they were obviously doing something very right.

And the American Bliss Jupiter was, also, a Bristol Jupiter built under licence.

 

[Admiral Beez]

I've always liked the look of Harley-Davidson's engines for the same reasons. Beautiful engines all.

Yes...

But not the new ones...

Many in my motorcycle circle think H-D will go bust in the early 2030s.

Here's What Harley-Davidson Should Do If It Wants to Survive

Here's how I'd right the Motor Co's ship if I were made CEO.

www.rideapart.com

 

[Admiral Beez]

If racking up hundreds of hours was your top requirement in the 30s then your only option was the AS Cheetah.

There seem to be a few AS Cheetahs still running. Though some of these may be the same engine, IDK.


View: https://www.youtube.com/watch?v=A_QKE7zzf50


View: https://www.youtube.com/watch?v=AKzy0YKlv20


View: https://www.youtube.com/watch?v=NcNF6bbyV24


View: https://www.youtube.com/watch?v=G6t-2LKafV4

 

[Snautzer01]

Phoahhh!!

No.

Double phoahhh !!

 

[MiTasol]

That first video is of a Cheetah XVII or later because it has the Hoover constant speed prop and smooth cowls. Those were used on the Anson 19 and later models. This may be one of the engines from VH-BAF which went to NZ and was re-engined with Cheetah X's and helmet cowls. If so the exhaust has been made a lot longer than when on BAF.

All the others appear to be Cheetah X's from an Airspeed Oxford although some/all may be a Cheetah IX from an Anson that has been fitted with an Oxford propeller. The Anson used a Fairey Reed metal prop and those are probably very hard to come by these days. I note the Omaka Anson has a wooden prop.

The last vid is of VH-BAF after re-engining in NZ. The mods were nothing to do with making that aircraft look modern. When the wood wings and tailplanes were outlawed because of the possibility of glue delamination Terry Brain went to England and purchased some late model, metal wing, Ansons and fitted the tailplanes, wings, and everything attached to the wings except the fuselage to his Anson freighter fleet. The late model engines with their constant speed props were a far safer option for operating than the lower powered engines with fixed pitch (and therefore non feathering) props. Structurally the tailplane and wings were a straight bolt on change although there were a bunch of control, wiring and instrumentation changes required for the engines and props.

Terry kept the Mk I fuselage because the fuselages for the later aircraft had a lot of maintenance issues that he wanted to avoid.

The photos below are from when I used to maintain that aircraft in the 1980s.