5 cylinder Radial Engine

[rdean]

I did not plan on building this engine as it is designed for an RC airplane and I never got into that hobby. It not something you can just set on the counter and start it up for a while to watch it run like I do with my other engines. It is recommended to use at least a 20" propeller and produces some serious horse power.
I ran across a set of plans for an Edwards 5 radial engine and was just looking through the pages when the master rod drawing caught my eye. It looked like an interesting part and I thought I will make just the rod for a conversation piece that's all. Well it turned out very nice almost excellent but it didn't demonstrate how the other rods were connected and the path that they followed.
The other four rods were all identical and a rather easy build so I decided to make them but now I had to make the link pins to hold the rods on. Well the link pins are held in position by the link pin retainer plate that captures the pins and hold everything together. Not exactly there is a C clip that holds the retainer plate in place but that clips on to the crank pin that is pressed into the crank shaft arm and there is a needle bearing in the master rod to match the crank pin. I might as well make the crankshaft too so I can attach the crank pin to something and really demonstrate how a radial engine works.

So now you see how all this got started and just keeps going.


I have now decided to try my hand at building this complex model engine and I will give it my best shot.


The crank shaft also has a counter weight that bolts onto the crank throw.



I will be following the plans closely but I will be using the materials I have on hand as much as possible.

This is an example of the engine. I hope mine looks half as good.


Thanks for looking
Ray

 

[DavidR8]

Definitely following along!

 

[StevSmar]

I have the plans for the Bentley BR2 which would be a fantastic project! Unlikely I’ll ever build it though, it’s too far down on my “projects I‘d like to do” list.

 

[rdean]

StevSmar a Bentley BR2 is a nine cylinder radial which is way above my pay rate. I am concerned that I may have bitten off more than I can chew with this 5 cylinder.

I will start with this 4.5 diameter aluminum round I had in the drawer for the main housing. I turned it down to 4" and started hollowing it out on the lathe.


There was a big pile of chips in the waste basket but after some time this appeared.


Now it goes over to the mill for many more operations.
I mounted the housing on the rotary table with a spoil board underneath so I could drill some holes all the way through and it will be a spacer for future operations..


I spot drilled the ten holes around the outer flange but as you can see there are 14 holes. The four with the black marker are in the wrong place. I kept reading the wrong numbers on the print but no foul as none of them will cause any problems in fact two will be milled away later and the other two will be covered by the rear plate.
There is a valley about an inch wide and a 1/4" deep in the bottom of the housing. At first I thought I would cut it while it was on the lathe but I had second thoughts. I decided to do the valley on the mill using the rotary table and it turned out much easier and more precise than I could have done it on the lathe.

Thanks for looking
Ray

 

[rdean]

The needle bearing came in for the master rod and it even fit. Now you can see how these pieces go together.


I flipped the rotary table up to vertical and using a milling head cut the flats on the housing.
Because the milling head does not cut to the outside edge of the head I had put a sacrificial piece of wood behind the housing so I could make the cut all the way across the face. There are 5 flats for the cylinders and 5 smaller flats for the mounting brackets.
This went remarkably well with no chatter.


A few views so far.






So far I have mostly stayed with the plans except for the rear crankshaft bearing. (32 X 12 X 10)
I had a bearing that was a little smaller on the OD and 0.312 in width. The bore was 0.500 and since I started with a 1/2" drill rod for the crankshaft I used my bearing. Being narrower I increased the thickness of the bearing lip in the housing in order for things to line up again.
Many more holes to drill and tap but not today.

Thanks for looking
Ray

 

[rdean]

Boring, drilling, and taping day.

I used the boring head in the mill for the cylinder holes.
Then drilled and taped 10 holes of 4-40 size for the rear plate screws.
And 20 holes drilled and taped 6-32 for the cylinder mounting screws.



No drill bits or taps were hurt making this part.


Another view with it all shined up.


I am very happy how this housing turned out. A major step forward.

What do you think?

Thanks for looking
Ray

 

[DavidR8]

That looks amazing!

 

[Janderso]

That looks amazing!

It sure does!!!
Well done sir

 

[rdean]

Thanks DavidR8 and Janderso comments are always welcome.
Ray

 

[StevSmar]

No drill bits or taps were hurt making this part.

That’s a great accomplishment- and no doubt a great relief!