18 Cylinders Isotta Fraschini (straight six-cylinder x3 )

[Foketry]

I found an old maintenance manual for this interesting engine built in Italy in 1930. 2 versions were made, one aeronautical, aluminum casing, one for naval use, all cast iron.
It's a very challenging project but I decided to build the airplane version, 1: 5 scaled engine model, I think it is a 6 cylinder engine multiplied 3 times, I hope to be able to make it work.
Technical features:
Bore =140 mm( 5,5 ")
Stroke=170 mm(6,7")
Displacement = 47.100 cc (2874 cubic inch)
Power Hp = 924
Some photos and drawings taken from the manual:

 

[Foketry]

 

[ddmckee54]

I was wondering if they staggered the cylinder alignment between the three banks. With that connecting rod I guess they didn't. It's going to be interesting to see what they did with the firing order.

 

[Foketry]

I was wondering if they staggered the cylinder alignment between the three banks. With that connecting rod I guess they didn't. It's going to be interesting to see what they did with the firing order.

yes the 3 cylinders are aligned, the firing order is also interesting, the number that appears in the diagram is not the cylinder number, but the ignition order, see for example the position 1-2-3 , 4-5-6 etc.

 

[G54AUST]

G'day Foketry.

This is going to be a very interesting build.

18 cylinders,
18 pistons,
36 spark plugs,
72 piston rings,
72 valves ..........
(plus spares)

This project will def keep the grey matter stirred.

If you don't mind, I'll be watching every step with keen interest. Bring it on Maestro .....

Kind Regards,

Trevor,
Melbourne, AU

 

[GreenTwin]

Each group of three firing cylinders creates a triangle, with alternating groups of three in an inverted triangle.

Balances the power strokes out evenly along the crank, or as evenly as possible I guess.

.

 

[kvom]

Just the wiring for the plugs looks to be a challenge, esp. if the wire doesn't scale.

 

[ajoeiam]

I found an old maintenance manual for this interesting engine built in Italy in 1930. 2 versions were made, one aeronautical, aluminum casing, one for naval use, all cast iron.
It's a very challenging project but I decided to build the airplane version, 1: 5 scaled engine model, I think it is a 6 cylinder engine multiplied 3 times, I hope to be able to make it work.
Technical features:
Bore =140 mm( 5,5 ")
Stroke=170 mm(6,7")
Displacement = 47.100 cc (2874 cubic inch)
Power Hp = 924
Some photos and drawings taken from the manual:

snip

Very interesting - - - - looking forward to your pics and descriptions as you work through the build!!!

 

[Foketry]

G'day Foketry.

This is going to be a very interesting build.

18 cylinders,
18 pistons,
36 spark plugs,
72 piston rings,
72 valves ..........
(plus spares)

This project will def keep the grey matter stirred.

If you don't mind, I'll be watching every step with keen interest. Bring it on Maestro .....

Kind Regards,

Trevor,
Melbourne, AU

Hi G54AUST
It is a very demanding projectI but I will try to simplify this engine, I don't need as many HP as the original Isotta engine

This old engine is also used for tractor pulling......

 

[ddmckee54]

Are you planning on casting a lot of the parts, or carving them from billet? (Or is it too early to tell yet?)

 

[Foketry]

Are you planning on casting a lot of the parts, or carving them from billet? (Or is it too early to tell yet?)

I plan to make the most important parts by casting aluminum with the casting mold made by 3D printer, some parts lost PLA

 

[Steamchick]

Good luck Foketry! I am sure you'll succeed, as (Like the merry few before you who take on huge challenges) I am sure you simply don't feel it is too big a project! (Most of us stick to single cylinders!). The u-tube clip sounded great!
K2

 

[SPOTTER]

It is a very demanding project, good work.
I follow you.

 

[Foketry]

I am working on the project, after having done some calculations on the stroke of the pistons to size the length of the connecting rods, the cylinders and the crankshaft, I have produced some drawings:
The original connecting rods are built with steel, with very thin thicknesses, my connecting rods are 7075 aluminum, I could not make the central connecting rods with the 2 + 2 thin lateral fins, I inverted, I drew the 2 lateral connecting rods with 2 fins rather than integral in the central connecting rod. I think i get more resistance. 2 hardened pins support the 2 lateral connecting rods.

 

[Steamchick]

I think it should work. You are not planning to fly on the aircraft when finished, are you?
K2

 

[johnmcc69]

This is going to be a good one! What a beast!

I like your con rod set up, that should work well.

John

 

[Foketry]

I think it should work. You are not planning to fly on the aircraft when finished, are you?
K2

For now I am not planning to fly, but in the near future ....

 

[Vixen]

I had similar deep undercuts to do on my Bristol Mercury master rods. They were also in steel, so I was able to use a small diamond stone mounted on a high speed spindle. The grinder was rotated, by hand, about the axis of the slave rod pin. You can see the extent of the undercut in the drawing.

So, it would be possible for you to make the Isotta Franschini conrods true to scale.


Mike

 

[G54AUST]

Nothing wrong with flying; just the sudden stop at the bottom when the engine cuts out .....

R...

T...

 

[Foketry]

I had similar deep undercuts to do on my Bristol Mercury master rods. They were also in steel, so I was able to use a small stone mounted on a high speed spindle. The grinder was rotated, by hand, about the axis of the slave rod pin. You can see the extent of the undercut in the drawing.

So, it would be possible for you to make the Isotta Franschini conrods true to scale.


Mike

View attachment 136831 View attachment 136832

Very ingenious your solution, I had tried a similar thing, I should have used a 4 mm ball endmill and then an flat endmill to remove the edges, with poor quality of the lateral conrod housings, I preferred an easier solution.
Even the second solution with T slot endmill you see below, doesn't work , only an EDM machine could machining these parts on a smaller scale.

Really nice and well worked your master conrod.