Aero Engine

[Heritech]

This is my first go at joining a forum and determining how it all works. In 2014 I was able to get a number of castings for a 1/6 size Pratt and Whitney Wasp Junior Radial Engine. I have done some machining and due to a number of reasons I have had to leave the project.
I am hopeful that I can get back to it soon.

The item that I would like to 'find' is the 9 cylinder head castings, which I understand were on sale in those days.

I wonder if somewhere in some-ones parts boxes there might be a lonesome set keen to get going again.

Many thanks, John.

 

[Olli-Matti]

Who made that kit back in the days? Do you have any pictures. Interesting topic the P&W wasp Jr. It is like 75cc in 1/6 scale?

 

[H Pearce]

Funny that this should come up today. I have just today been in contact with the person who is currently producing those castings. he currently doesn't have a full set available. i have asked for an indication of timing and will post here when i find out. I don't imagine it will be soon. PM me for contact details as i don't want to put his personal email on an open forum where all the spammers can find it.

 

[Herk]

The Wasp Jr was 985 cubic inch so a 1/6 scale version would be a whopping 164 cubic inches or 2660 cc, while a 1/16 scale would be 61.6 cid or about 1000 cc. A 1/6 scale version would be quite impressive and might end you up with something like this Kitfox with a Rotec

 

[Peter Twissell]

Herk, when an engine is scaled, it's capacity is scaled by the cube of the scaling factor. This is because not only is the stroke scaled, but also the bore and the capacity of each cylinder is given by PI x (1/2 bore) squared x stroke.
Thus a 1/6 scale engine has 1/(6x6x6) the capacity of the full size.
That is 1/216, so the P&W wasp in 1/6 scale will be 985/216 cubic inches, =4.56 ci or about 75cc.
Pete.

 

[ninefinger]

FYI - the castings were originally made by Vernal Engineering ( Bruce Satra ). Not sure who has the dies now but they are very fine castings. I must say that the engine is not for beginners, myself being one who has been picking away at this engine for over 10 years (but very infrequently).

 

[Aerostar55]

This is my first go at joining a forum and determining how it all works. In 2014 I was able to get a number of castings for a 1/6 size Pratt and Whitney Wasp Junior Radial Engine. I have done some machining and due to a number of reasons I have had to leave the project.
I am hopeful that I can get back to it soon.

The item that I would like to 'find' is the 9 cylinder head castings, which I understand were on sale in those days.

I wonder if somewhere in some-ones parts boxes there might be a lonesome set keen to get going again.

Many thanks, John.

John - Are you talking about the R-985 produced by Bruce Satra and drawn by Bob Roach ?

 

[Heritech]

John - Are you talking about the R-985 produced by Bruce Satra and drawn by Bob Roach ?

Yes I am. As noted earlier, I have a collection of castings and I have done some machining over the years. I am looking for a set of 9 cylinders.

The item is on Drawing J18, part 40. A less attractive solution would be guidance to a source of raw materials - 4140 Steel, 35 o/d, 20 i/d and 400 long.

Can someone help here. and - can someone tell me what push notifications are?

Regards, John Gibson ( Heritech).

 

[Heritech]

Funny that this should come up today. I have just today been in contact with the person who is currently producing those castings. he currently doesn't have a full set available. i have asked for an indication of timing and will post here when i find out. I don't imagine it will be soon. PM me for contact details as i don't want to put his personal email on an open forum where all the spammers can find it.

Hi There, thanks for the comment, as you will know I am seeking a set of 1/6 scale radial engine cylinders for a Pratt & Whitney mode at a reasonable price. Can you help?

 

[ninefinger]

Hi John,

The cylinders (Drawing J18) were never available as a casting to my knowledge. There was someone offering them machined on CNC but I never investigated to far as I was rather short on money back then (more than 10 years ago).

The cylinders can be machined but are a finicky operation, and my experience shows its best doing the fins on a rotary table on the mill with slitting saws - this was recommended to me and worked very well compared to trying to cut fins on the lathe. The rest of the cylinder machining is rather standard except maybe the thread for the head is quite fine. BTW no need for a buttress thread as shown in the drawings, make both the head and the cylinder with regular 60 degree V threads, this is how my cylinder heads were threaded as supplied to me by Bruce Satra.

Lastly - the material call out of 4140 is for a workhorse engine to be run alot. I choose to use free machining steel to make machining a lot easier with the trade off for longevity - but as I will likely run it only very occasionally I think this is ok.

Regards,
Mike

 

[Heritech]

Hi John,

The cylinders (Drawing J18) were never available as a casting to my knowledge. There was someone offering them machined on CNC but I never investigated to far as I was rather short on money back then (more than 10 years ago).

The cylinders can be machined but are a finicky operation, and my experience shows its best doing the fins on a rotary table on the mill with slitting saws - this was recommended to me and worked very well compared to trying to cut fins on the lathe. The rest of the cylinder machining is rather standard except maybe the thread for the head is quite fine. BTW no need for a buttress thread as shown in the drawings, make both the head and the cylinder with regular 60 degree V threads, this is how my cylinder heads were threaded as supplied to me by Bruce Satra.

Lastly - the material call out of 4140 is for a workhorse engine to be run alot. I choose to use free machining steel to make machining a lot easier with the trade off for longevity - but as I will likely run it only very occasionally I think this is ok.

Regards,
Mike

Hi There Mike,
Thank you very much for your response to my request for Cylinders on the P&W aero. It is good to see your advice re the materials and the threads. Your comment re longevity is very valid and I will move in this direction. Thanks again. John

 

[GrahamJTaylor49]

A very knowledgeable gentleman that I have heard of, by the name of Alan Milliard, has made a motor from 2 cylinders from a radial engine from a DC3. Calls it the Milliards Flyer and is a 5 ltr vee twin motorcycle. Look very retro and goes like the devil. Look it up on U-Tube.

 

[GrahamJTaylor49]

Sorry, that's "The Flying Milliard".

 

[comstock-friend]

It's Millyard. The links are: