Spikey Posted December 3, 2015 Share Posted December 3, 2015 Can somebody please solve one of life's great mysteries ans tell me the exact purpose of the power supply/generator set powered by a 500cc Triumph engin that was apparently used on Lancasters? Under what circumstances was it used? In the air or just on the ground? Where did the exhaust go? How long did it run on a tankful? And so on. I've never been able to make much sense of this ... Quote Link to comment Share on other sites More sharing options...
Daithi O Buitigh Posted December 3, 2015 Share Posted December 3, 2015 According to 'Triumph - a Century of Passion and Power' it was a detuned 500 cc Speed Twin called an 'Airborne Auxiliary Power Plant' (nicknamed A squared P squared) and was used for in flight battery charging. More details on it here Quote Link to comment Share on other sites More sharing options...
selwyn smith Posted December 3, 2015 Share Posted December 3, 2015 Most large aircraft have an APU which can supply electrics and air for engine starting. Early units, such as that fitted to Vulcans, supplied electrics only as an emergency back up and a separate air start trolley was required to start the engines. I believe the Lancaster required a 'Trolley Acc.' for engine starting as the start system was by electric motor. The triumph engine was probably a back up to keep the electrics going if the main engine generators were lost. Quote Link to comment Share on other sites More sharing options...
Daithi O Buitigh Posted December 3, 2015 Share Posted December 3, 2015 The Trolley Acc El Start' was a very heavy bit of gear (about the size of a VW beetle) and, as you said, was used to provide start up power to the first engine. Once that started, the onboard generator could then start the remaining three. I've seen it used on Lincolns with the Griffin engines and also on Shackletons However, the A squared P squared was as I said, simply an in-flight battery charger as stated in the Triumph book and had nothing to do with starting the engines. A similar syatem was used in B 29s and was referred to (even in the official manuals) as the 'putt-putt'. The idea actually dates back to the Sopwith Nighthawk in WW1 which had an AAPP to power the searchlight Quote Link to comment Share on other sites More sharing options...
trevor wood 2 Posted December 4, 2015 Share Posted December 4, 2015 The Lincoln (and Tudor) had annular cowled Merlins, not Griffons. Quote Link to comment Share on other sites More sharing options...
Former Member Posted December 4, 2015 Share Posted December 4, 2015 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Spikey Posted December 4, 2015 Author Share Posted December 4, 2015 Posted by Daithi O Buitigh on 03/12/2015 22:20:55: However, the A squared P squared was as I said, simply an in-flight battery charger That's the bit that's always had me puzzled. Am I correct in assuming that it was there just as a back-up in the event of engine-driven generator problems? How was it started, and where did the exhaust from it go? Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted December 4, 2015 Share Posted December 4, 2015 I can tell you that the ordinary trolly acc which provided 12 volts was used for starting Lancs at least after the war. Also that the Lancs in the Maritime Reconnaissance School did not have that APU installed. The trolly acc was plugged in in the front wall of the port undercarriage bay. I can remember that only too well because one day I did the standard thing after starting a Lanc up and pulled the plug out from the ground. The plug wasabouyt 4" dimapeter and 8" long.on the end on the heavy cable, It came down, bounced off the tyre and smacked me just over the right eye which meant that I was escorted to sick quarters for treatment. I still have a very small, faint scar there Quote Link to comment Share on other sites More sharing options...
ted hughes Posted December 4, 2015 Share Posted December 4, 2015 If you haven't seen this program, it is truly inspiring. It is the story of a team bringing a B29 back to life and attempting to fly it home. I wont spoil it, but the AAPP played a major part:**LINK** Quote Link to comment Share on other sites More sharing options...
Daithi O Buitigh Posted December 4, 2015 Share Posted December 4, 2015 Aircraft electrical systems are 24 Volts but the AAPP presumably was a backup. The normal 1,500 Watt generators were driven by the two inboard engines and, if one or both had to be feathered there would be insufficient or no charging current and the AAPP would take over Lots of info on the Lanc, based on the Pilots' Notes here including this bit: "...Spinning and acrobatics are not permitted. Violent use of the rudder at high speeds should be avoided. ..." Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted December 4, 2015 Share Posted December 4, 2015 Posted by Daithi O Buitigh on 04/12/2015 12:21:46: Aircraft electrical systems are 24 Volts but the AAPP presumably was a backup. The normal 1,500 Watt generators were driven by the two inboard engines and, if one or both had to be feathered there would be insufficient or no charging current and the AAPP would take over Lots of info on the Lanc, based on the Pilots' Notes here including this bit: "...Spinning and acrobatics are not permitted. Violent use of the rudder at high speeds should be avoided. ..." Of course I goofed. Just shows how much one can forget in 50 years. Not 12 volts but 24 as you said. Still remember the crack on the head though. Perhaps I can blames that for being so stupid/ Quote Link to comment Share on other sites More sharing options...
Andy48 Posted December 4, 2015 Share Posted December 4, 2015 ... or later genius Quote Link to comment Share on other sites More sharing options...
Shaunie Posted December 5, 2015 Share Posted December 5, 2015 I went to the national motorcycle museum (off the M42) yesterday and I was relating this thread to the mate of mine I went with. We were going past the triumph collection at the time and there it was, a lancaster APU, for some bizarre reason I never took a photo of it. Shaunie. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted December 5, 2015 Share Posted December 5, 2015 As I recall, the aluminium top end formed the basis for the post war Triumph 500 GP racing engine Quote Link to comment Share on other sites More sharing options...
Spikey Posted December 6, 2015 Author Share Posted December 6, 2015 So ... we're agreed that it was intended for in-flight battery charging only, and if Lancs in the Maritime Reconnaissance School didn't have them fitted, it seems to me that the unit was a hostilities-only thing. Looks like I'll always be wondering where the exhaust went ... Quote Link to comment Share on other sites More sharing options...
Robert Armstrong 2 Posted December 6, 2015 Share Posted December 6, 2015 Anyone got the Haynes 'Lancaster Manual'? Quote Link to comment Share on other sites More sharing options...
Kevin Wilson Posted December 6, 2015 Share Posted December 6, 2015 One of those would make a great field charger for batteries. I bet there arn't many left in working comndition. An uneducated guess regarding the exhaust would be that it got poked through a hole in the fus as close to the unit as possible. Quote Link to comment Share on other sites More sharing options...
Spikey Posted December 6, 2015 Author Share Posted December 6, 2015 Posted by Robert Armstrong 2 on 06/12/2015 07:57:20: Anyone got the Haynes 'Lancaster Manual'? I got it out the library a few years ago and IIRC there was no mention of it in there. One reason why I've always been intrigued about this thing is that I once owned a Triumph which had the barrel with the lugs on into which were drilled and tapped holes for the cowling when used on the AAPP, and I remember seeing a few of them in amongst the BSA M20s and the Daimler scout cars and so on in a local scrapyard. Posted by Kevin Wilson on 06/12/2015 09:39:16: An uneducated guess regarding the exhaust would be that it got poked through a hole in the fus as close to the unit as possible. Indeed, but having flown in the back of Varsity, Valetta and on one memorable occasion a Shackleton (these being built along basically the same lines as the Lancaster), that's always seemed a bit unlikely to me. However, I've asked plenty of folks over the years and wasted a lot of time on Google, but I've never managed to do any better than that ... Edited By Spikey on 06/12/2015 10:30:13 Edited By Spikey on 06/12/2015 10:32:08 Quote Link to comment Share on other sites More sharing options...
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