Rob G Posted February 28, 2017 Share Posted February 28, 2017 Gents, I'm wondering if anyone has access to a Merlin without its prop, or possibly a service manual. I'm trying to find out the diameter and spline count of the Merlin's prop/output shaft. Both diameters (spline and outer end) would be useful, but not critical. Absolute precision isn't required - the nearest mm will do fine. As an alternative, does anyone know of any dimensioned drawings anywhere online? I've been looking and can't find diddly. Thanks. Link to comment Share on other sites More sharing options...
Admiral Puff Posted February 28, 2017 Share Posted February 28, 2017 Can't give you an immediate answer. It's complicated by the fact that, IIRC, the number varies according to whether it's a Rolls-Royce or Packard engine. You could try contacting Judy Pay's Old Aeroplane Company at Tyabb - if anyone can tell you, they can. Alternatively, send a message to Gary at Red Roo and ask him to pass on a message to Dick Hourigan, who is also likely to know. 1 Link to comment Share on other sites More sharing options...
Rob G Posted February 28, 2017 Author Share Posted February 28, 2017 Thanks Admiral Puff- contacting the Real World was my Plan B. Basically, I hate disturbing people with unsolicited emails. <shrug> Anyone who's here is doing it under their own volition. It's for a 72nd Mosquito, so the 'exact' details probably don't matter a great deal - 24 vs 30 splines (or whatever) isn't likely to be counted. I'll start looking those email addresses up, thanks. Link to comment Share on other sites More sharing options...
Admiral Puff Posted February 28, 2017 Share Posted February 28, 2017 No probs. Tell Gary that DC suggested you contact him - that way I'll cop the flak ... I thought that we'd covered this in Southern Cross Mustangs, but I've just checked and we didn't. We did cover prop types, but not down to that detail. Link to comment Share on other sites More sharing options...
Kahunaminor Posted February 28, 2017 Share Posted February 28, 2017 Hello, According to my copy of Spitfire Engineered by Monforton it gives these figures for a Mk IX Spitfire: "36 splines, 9 castellations, 0.078" (1.98mm) pitch thread." It is double dutch to me but if it helps? Regards, 1 Link to comment Share on other sites More sharing options...
Rob G Posted February 28, 2017 Author Share Posted February 28, 2017 Lol thanks Kahunaminor. It all makes sense to me. Does it give any shaft diameters perchance? (Basically, splines are the 'teeth' on the outside of the shaft that grip the inside of the prop hub to lock it to the shaft, castellations are the up and down bits (like castle battlements) on the end that are used to lock the prop nut in place, and thread pitch is the distance between the tops of adjacent threads. Clever people, those Dutch. ) 1 Link to comment Share on other sites More sharing options...
JasonC Posted February 28, 2017 Share Posted February 28, 2017 Just been and measured a Merlin 22 (36 splines). Error is probably about +/- 0.5mm. Diameter over the splines: 95.2mm I would estimate the splines are about 2-3mm deep. Diameter over the narrower, threaded portion at the front: 75.3mm The latter over the tops of the threads. This particular shaft was not castellated at the front. Best of luck carving 36 splines in 1/72! regards, Jason 2 Link to comment Share on other sites More sharing options...
Work In Progress Posted February 28, 2017 Share Posted February 28, 2017 I think in 1/72 all you can hope do to is take a section of slightly oversize rod and scrape along with with a fine tooth razor saw, surely? 1 Link to comment Share on other sites More sharing options...
JasonC Posted February 28, 2017 Share Posted February 28, 2017 Or press in the spline slots using a scalpel blade. Still fiddly work with a rod that's less than 1.5mm across! J. 1 Link to comment Share on other sites More sharing options...
Rob G Posted March 1, 2017 Author Share Posted March 1, 2017 It's going to be interesting, fo' sho'. As has been noted, some fine scrapes may be all that can be done. Thank you to all who responded, much appreciated. Now another question, if I may - where can I source 5 and 6 stub exhausts for a 1/72 Mosquito B.Mk.IV? I need outboard 6s and inboard 5s. Can't find any resin 6 stackers anywhere. If I have to, I'll buy another kit, but I'd rather just keep on choochin' with the Hasegawa one that I have, which only has shrouded exhausts in it. Thanks (again). Link to comment Share on other sites More sharing options...
Rob G Posted March 2, 2017 Author Share Posted March 2, 2017 Anyone? Link to comment Share on other sites More sharing options...
JasonC Posted March 2, 2017 Share Posted March 2, 2017 Well, one solution is to order an extra set and cut off a single stack to build a six stack unit from the existing fives. If there's no dedicated aftermarket then that's likely your best option. J. 1 Link to comment Share on other sites More sharing options...
Rob G Posted March 2, 2017 Author Share Posted March 2, 2017 15 minutes ago, JasonC said: Well, one solution is to order an extra set and cut off a single stack to build a six stack unit from the existing fives. If there's no dedicated aftermarket then that's likely your best option. J. That's the conclusion that much searching had resulted in for me, too. Because I have spare money to throw away... :eyeroll: :sigh: Oh well. Anyone want to buy a set of 4/5 stack Mosquito exhausts? (That's a joke, Mr Mod.) Link to comment Share on other sites More sharing options...
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