Pratt and Whitney R-2800 Double Wasp engine

[AlbertD]

I have been studying photos of this engine to detail my Corsair's R-2800. To me it looks like there are ignition wires going to both front and back of each cylinder. It looks like the front cylinder has one wire going directly into the front and one going over the top for the back of that cylinder. Then you have two wires between each front cylinder going to the back of the engine for each of those cylinders. Am I seeing that right?

 

Thanks for any help clearing this up for me.

[Juggernut]

R-2800-8/8W (B series engine): 18 cylinders = 36 spark plugs with one high tension lead each,front and back (both rows).  On this version, there are two magnetos and they're both contained in one single unit, up front, 12 o'clock mounted between the two distributors (10 and 2 o'clock) on the prop reduction gearcase.  It's a Bendix-Scintilla DF18LN dual magneto (I think it's a LN but some are RN's...left turning vs. right turning).  Both distributors and the ignition harness are either pressurized(distributors) or hermetically sealed (harness) to prevent ignition flashover (spark jumping from one lead/contact to another within the distributor) at high altitude which plays havoc with engine operation. Ignition leads are high voltage carrying cable, surrounded by braided metallic conductive cable (to eliminate radio noise from the ignition system) and then covered in rubber.

 

Firing order of an R-2800 18 cylinder engine is:   +11, -7 starting with the no. 1 cylinder.  1+11=13-7=6+11=17-7=10 and so on, until you get back to cylinder No. 1.  To figure out the firing order of a 14 cylinder radial engine, the numbers are +9, -5.

 

Probably more than you ever wanted to know about an R-2800-8/8W engine but helps you understand what you're modeling.

Edited December 29, 2020 by Juggernut
Edited for readability

[AlbertD]

5 hours ago, Jennings Heilig said:

All piston aero engines have two separate ignition systems (in case one fails).  So each cylinder has at least two spark plugs, one attached to each separate magneto.  Yes, you’re seeing it right.

Thanks for confirming what I was seeing. 

 

41 minutes ago, Juggernut said:

R-2800-8/8W (B series engine): 18 cylinders = 36 spark plugs with one high tension lead each,front and back (both rows).  On this version, there are two magnetos and they're both contained in one single unit, up front, 12 o'clock mounted between the two distributors (10 and 2 o'clock) on the prop reduction gearcase.  It's a Bendix-Scintilla DF18LN dual magneto (I think it's a LN but some are RN's...left turning vs. right turning).  Both distributors and the ignition harness are either pressurized(distributors) or hermetically sealed (harness) to prevent ignition flashover (spark jumping from one lead/contact to another within the distributor) at high altitude which plays havoc with engine operation. Ignition leads are high voltage carrying cable, surrounded by braided metallic conductive cable (to eliminate radio noise from the ignition system) and then covered in rubber.

 

Firing order of an R-2800 18 cylinder engine is:   +11, -7 starting with the no. 1 cylinder.  1+11=13-7=6+11=17-7=10 and so on, until you get back to cylinder No. 1.  To figure out the firing order of a 14 cylinder radial engine, the numbers are +9, -5.

 

Probably more than you ever wanted to know about an R-2800-8/8W engine but helps you understand what you're modeling.

Not too much information at all. I love the mechanics of the airplanes and engines in general. You also answered the question of the braided shielding on the cables. I might try to replicate that for the heck of it instead of using the standard lead wire. I have some of the Anyz braided wire in .05mm which might be close enough. I almost bought a period R-2800 service manual on ebay but $50 plus shipping was more than I wanted to pay. Thanks for taking the time to share your knowledge. 

[Cheetah11]

 

16 hours ago, Jennings Heilig said:

All piston aero engines have two separate ignition systems (in case one fails).  So each cylinder has at least two spark plugs, one attached to each separate magneto.  Yes, you’re seeing it right.

 

Hi Jennings

 

All but aero diesel engines. The Russian post war 42 cylinder turbo charged diesel radials for the use in bombers were impressive engineering achievements. When turbo prop engines overtook piston engines in these applications the radials were re-engineered for marine use in fast patrol boats.

 

 

 

 

 

 

 

[Juggernut]

Quote

I almost bought a period R-2800 service manual on ebay but $50 plus shipping was more than I wanted to pay.

 

Don't do that unless you really want that paper copy.  There are sites like Aircorps Library and Avialogs that have a lot of manuals that you can download and save as PDF documents (Avialogs I think is the only site that will let you download the documents...with a paid subscription) and a years subscription to both would probably be less than what you would've paid for that paper manual alone with the shipping. 

 

I'm a member of Aircorps Library and I can tell you that they have a copy of the R-2800 maintenance manual in their documents.  They also have a lot of manuals (blueprints and manuals) for the F4U Corsair.

Edited December 29, 2020 by Juggernut

[AlbertD]

11 hours ago, Juggernut said:

 

Don't do that unless you really want that paper copy.  There are sites like Aircorps Library and Avialogs that have a lot of manuals that you can download and save as PDF documents (Avialogs I think is the only site that will let you download the documents...with a paid subscription) and a years subscription to both would probably be less than what you would've paid for that paper manual alone with the shipping. 

 

I'm a member of Aircorps Library and I can tell you that they have a copy of the R-2800 maintenance manual in their documents.  They also have a lot of manuals (blueprints and manuals) for the F4U Corsair.

Great, thank you. I'll sure enjoy it.