The Aerodrome Forum - View Single Post

John McKenzie · 3 July 2009, 01:16 PM

Hi there Tengew , thanks for that.....Although this is the case with some types such as Sopwith and maybe others , where in the case of diverse manufacturers making up their own drawings from "pattern" aircraft , supplied by the parent company , ..A wing or aileron from one firm , may not fit the same or a mateing part from another firm.........This was NOT the case with Royal Aircraft Factory design products.....With proper engineering design / drawing office , all drawings contained " parts must not be altered to effect interchangabilaty "....(this applied of course to the actual drawing) ....Also within each schedule , there was a list of drawings that fitted together. Therefor , all parts within a schedule could be made by anyone , and , provided the "limits on tolerances" were complied with , then everything would go together nicely ,. however , if the part was out of tolerance (and the tollerance would vary depending on the part )..then it would be rejected as unsuitable....It was in fact the Royal Aircraft Factory (RAF) that set up the pattern for standardisation that has come down , developed ,to us today .....For example , the identification part numbers for bolts , nut etc. ad infinitum,.....RAF (Not Royal air force ) drawings /parts became standard parts within the british A.G.S. designation system , which were used by all manufacturers as it became available...Thus , any small suitable machine shop , once an inspection scheme had been set up , could manufacture to Governement contract say 2000 of AGS157b or whatever , These would go into government stores to be drawn out by manufacturers as per contract requirement....Eg. Once a special Sopwith part , The petrol filler /neck /flange , on a Snipe say ,would now be a standard AGS part ,designed (perhaps originaly for the BE2 series ,)by the RAF at Farnborough......And (if the same AGS number ) would be interchangeable from one off say RE8 .......With reference to munitions ,(from memory ) the BSA (Birmingham Small Arms ) drawings for Lewis MG's have two or three tolerance bands for critical parts...High(stamped H ) med ? & Low (stamped L ).....Parts with the same letter will fit together ......It would be different with "Large " ordinance ,probably as you say , perhaps because of physical size and economics ?...........A wing from any manufacturers BE2c/d ..will fit any FE2b..(provided they are made to a common schedule and are within inspection tolerances ).....................

..........The critical thing with any of these "Large" reproductions ,especially if you only have a small workshop , is First Checking and adjusting all the relavent drawings for compatabilaty and then makeing all the parts WITHIN the Strict TOLERANCES ,.........Therein lies the difficult engineering part....

....." Then , any old Tom , Dick & Harry can put it together "

........Regards...John.

3 July 2009, 01:16 PM	#150 (permalink)
John McKenzie Forum Ace Join Date: Oct 2008 Location: Southampton U.K. Posts: 732	Interchangeability of parts. Hi there Tengew , thanks for that.....Although this is the case with some types such as Sopwith and maybe others , where in the case of diverse manufacturers making up their own drawings from "pattern" aircraft , supplied by the parent company , ..A wing or aileron from one firm , may not fit the same or a mateing part from another firm.........This was NOT the case with Royal Aircraft Factory design products.....With proper engineering design / drawing office , all drawings contained " parts must not be altered to effect interchangabilaty "....(this applied of course to the actual drawing) ....Also within each schedule , there was a list of drawings that fitted together. Therefor , all parts within a schedule could be made by anyone , and , provided the "limits on tolerances" were complied with , then everything would go together nicely ,. however , if the part was out of tolerance (and the tollerance would vary depending on the part )..then it would be rejected as unsuitable....It was in fact the Royal Aircraft Factory (RAF) that set up the pattern for standardisation that has come down , developed ,to us today .....For example , the identification part numbers for bolts , nut etc. ad infinitum,.....RAF (Not Royal air force ) drawings /parts became standard parts within the british A.G.S. designation system , which were used by all manufacturers as it became available...Thus , any small suitable machine shop , once an inspection scheme had been set up , could manufacture to Governement contract say 2000 of AGS157b or whatever , These would go into government stores to be drawn out by manufacturers as per contract requirement....Eg. Once a special Sopwith part , The petrol filler /neck /flange , on a Snipe say ,would now be a standard AGS part ,designed (perhaps originaly for the BE2 series ,)by the RAF at Farnborough......And (if the same AGS number ) would be interchangeable from one off say RE8 .......With reference to munitions ,(from memory ) the BSA (Birmingham Small Arms ) drawings for Lewis MG's have two or three tolerance bands for critical parts...High(stamped H ) med ? & Low (stamped L ).....Parts with the same letter will fit together ......It would be different with "Large " ordinance ,probably as you say , perhaps because of physical size and economics ?...........A wing from any manufacturers BE2c/d ..will fit any FE2b..(provided they are made to a common schedule and are within inspection tolerances )...............................The critical thing with any of these "Large" reproductions ,especially if you only have a small workshop , is First Checking and adjusting all the relavent drawings for compatabilaty and then makeing all the parts WITHIN the Strict TOLERANCES ,.........Therein lies the difficult engineering part........." Then , any old Tom , Dick & Harry can put it together "........Regards...John.