Another Radial - this time 18 Cylinders

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I also have a full set of dynamotive merlin castings. I purchased last summer so must of got one of the last sets.
I think you should make a start on this great engine and then I can use all your knowledge from the build when I finally get round to building mine.
His work truly is remarkable. I found his webpage sometime ago when I was researching the Merlin and drooled over his model. He must do his own castings not to mention all the research needed to come up with a set of plans from which to work. In the video what you seem to hear most is all those internal gears. He probably included every single one of them. He is definitely one of a kind. It would be an honor to spend a month with him in his shop watching him work. - Terry
What about a pratt and whitney r1830 radial from castings 1/6 scale. Bruce satra made the castings and I believe paul knapp has taken over.
What about a pratt and whitney r1830 radial from castings 1/6 scale. Bruce satra made the castings and I believe paul knapp has taken over.

I have trouble with those really tiny parts nowadays. I have trouble seeing them, my fingers can't hold them, and someone keeps coming into the shop to hide them from me. - Terry:wall:
I'm so glad I got caught up with this thread. Thanks for all of your detailed diagnostics and math, it's really helping us that are getting started designing an engine from scratch! I really love the sound of the thing. Very nice!
Hi Terry

I'm attempting to model an 18 cylinder radial in Pro/Engineer, similiar to Solidworks. This is just a bit of fun. I don't have the skills to even begin being able to produce one.

As you can see from the attached images, my connecting rods are too short and approaching TDC, the piston is still only half way up the bore. I'm doing this purely from photographic reference as I don't own Hodgson's drawings. The PCD of the journals on the crank and master rod is all correct so I must have the length of the master rod and slave rods considerably shorter than they should be. What length are they?

If the engine is allowed to sit a few days, there is also some oil from one or two lower exhaust pipes whose cylinders were left standing with open exhaust valves. If I were starting the engine build over, I would include pushrod tubes.

Hi Terry. Early on the build thread you mentioned not bothering with pushrod tubes (or maybe you just preferred the exposed pushrods to see motion etc). Later in post #374 you mentioned tubes might be a good idea in hindsight. Can you elaborate? I didn't quite get the connection between the oil/exhaust & the tubes. Just overall cleanliness of grit getting into the pushrod ball end interfaces? Or would tubes somehow be used to contain lubrication? How is any lubrication contained on the upper pushrod ends in any event? (what prevents them from running dry?)

I could have sworn there was a pic/vid showing tubes on your engine, but now I cant seem to find. Maybe I'm mixed up with this build. (I'm having an issue accommodating the 3d pushrod/tube geometry, I think that's what these ball-in-socket ends are all about).

Anyway, just wondering if you had thoughts or since modded your engine in that regard.

I didn't use pushrod tubes on either of my radials. What you may be remembering was the small diameter hypodermic tubing I added to tbe pushrods on my 18 cylinder radial in order to build up their diameters for cosmetic reasons. If I were doing it over again I would include pushrod tubes because most of the oil leakage over time comes from the lower lifter bushing clearances. - Terry
I extended the design of the 9 cylinder radial plan set that I purchased from to come up with my 18 cylinder radial. Ageless also offers plans for an 18 cylinder engine. - Terry
WOW, JUST WOW !!! th_confused0052 I've seen smaller models (5/7/9 cylinders), but haven't seen a running 18-cylinder.

None of us are worthy !!! :bow: :bow:

Hi Terry,
Totally gob smacked,lost for words,just have to watch.
Thank you for for taking me on the journey.
im just getting started on Solid works modeling of this cool engine. It’s a bit overwhelming at first but your nice description and pictures really are helping. I’m used to building 2-3000 hp Hemi Engine not something micro miniature. One of my sons just bought a new mill and lathe. Not full sized thing like you have however. We debated a long time about getting a cnc set up but we each have different products and goals. I’m an engineer by trade with toolmaker experience so I’m comfortable around machines and chip making.
my goal to start is to complete the three d model with the fixtures so I have a better feel for making this engine. There are a lot of parts and fixtures .

anyway it really nice to se the beautiful machined parts. I hope I can at least show something similar. I’ve had some medical issues so my shop efforts will take much care on my part. I must not let my doctor know of this. He has restricted from even playing tiddlywinks winkys due to eye injury.LOL.



Byron Nelson

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I’ve been away for a while with login issues then this double vision thing came up . I hope you can forgive some spelling and context mistakes it’s very difficult to type.I do proof read but it hard to se some mistakes with a patch eye and magnifying glass. As a result I’m really limited in the shop. I’m not eve supposed to be thereno Ridley winks either. Without safety glasses.LOL

Anyway I think I understand your crankshaft. I came the same conclusion that many trial assemblies would be necessary so pressing the crank together seemed out of the question. Many years ago when we first started using narrowed rear ends in our dragsters. Custom axels were not available yet. The solution was to use a large axel cutbit off the flange and machine it for a common bearing. Then bore the old hub or new one for a press fit and weld it on the seam. It worked for a while but post weld heat treat was hard to get so the solution was to drill for a dowel pin on the joint line and weld this apparently reduced the stress on the welded joint as there were few issues until the very high power motors were developed axel came about then too . It appears that you have come up with about the same solution without the weld do the cranks are more easily separated. Looking at the original full size Gleason gear works created a spline and socket with a massive bolt to hold the crank in alighment for assembly. The square key seems ok so that’s good if the tool blank is square an true. So nice job with a nasty problem. I haven’t finished my cadd model yet due to this med issue. There is no glasses solution to fix a messed up brain in fortunately. I’m reduced to transferring my old machine shop and welding skills to my son and grand son. Twin nice people to have around. My cat helps with personal comfort. I’m training her to wak on a leash so I can get out and about.. I’ve looked into service dogs but the stimulus package is still unsolved. There may be help later. Service dogs are very expensive 10_20 grand or more. I did find two retired ones but they were on opposite coasts and transportation was just too much. You can fly out and bring them back but sometime you have to buy a seat. Often you may need proof that you have had instructive trading with a specific dog especially a large breed. The really can only sk two question. Is this a service dog. If you respond yes they can ask what service do’s he provide. You explain briefly but no demo is necessary. The dog must be very stable and be quiet. No other documentation is necessary or legal there are no registry in the us recognized by threads. Regardless of what sales people tell you. Flashing a fancy document or business car can get you removed in many states. More and more are becoming wise to fake registries. Our state had laws pertaining to this but not police enforced.vests are not necessary you don’t have to be polite if someone tries to pet or distract your dog. My 6 yr old saw the star trek episode that a guy touched 7 of 9 inappropriately and she said remove your hand before I remove it from your arm. Never under estimate a 6 yr old. He was holding my K9 dog leash and a guy reached over to pet the dog. My son said touch me or this dog and you may have one less @&$? hand. 100 pounds of dog 60 pound boy. The guy backed away the dog had a smile that only German shepherds have. He probably had been around dad on a bad day. LOL. Kids are more observant than you think.
Nice job on your parts. I’ll try and follow more closely from here.


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