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Packard Merlin boost regulator

 
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gbaddeley



Joined: 03 May 2011
Posts: 2

PostPosted: Mon May 09, 2011 04:50    Post subject: Packard Merlin boost regulator Reply with quote

Hi all;

A friend of mine is working on a flightsim project and he has asked me about the operation of the boost regulator on a V-1650-7. We have a copy of the engine manual, but it doesn't go into the kind of detail that we need. So, I have joined AEHS in the hope that there are some members with this kind of in-depth knowledge.

So, here we go, the questions are verbatim as received;

First question: The relay piston as far as I can understand from several manuals is retained to the forward position with the spring, until pressure difference between blower inlet and outlet is insufficient for reliable operation. This position corresponds to maximal reverse effect of the relay piston to the butterfly valve (BV). If engine rpm grow then the piston gets controlled and travels aft opening BV even if the throttle lever does not move. If so, what is rpm value when this transition occurs? Is it noticable?

Second question: The second Q is about emergency boost. As far as I can see it is done by opening the extra port form the pressure chamber to depression area so the pressure is determined by incoming and outgoing air. So the pressure measured becomes lower than true MP and the boost regulator force it obtaining emergency boost.
Is it correct?



Many thanks in advance to anyone able to give me some insight!

All the best;

Greg
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dbirch



Joined: 30 Apr 2007
Posts: 14

PostPosted: Sat Aug 27, 2011 12:02    Post subject: Merlin Automatic Boost Control Reply with quote

Greg,

In the event that you have not had a reply to your query, I have a description of how it all works. Will scan the pages next week and send to Kim to put on to apropriate section of website.


Dave Birch
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kmccutcheon



Joined: 13 Jul 2003
Posts: 197
Location: Huntsville, Alabama USA

PostPosted: Fri Sep 02, 2011 10:44    Post subject: Reply with quote

The Rolls-Royce Merlin Automatic Boost Control article is available for viewing at
http://www.enginehistory.org/Piston/Rolls-Royce/R-RmerlinABC/R-RmerlinABC.shtml
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Kimble D. McCutcheon
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dirwin



Joined: 21 Aug 2010
Posts: 11
Location: West Sussex, England.

PostPosted: Sun Sep 04, 2011 14:17    Post subject: Reply with quote

The above article provides the clearest overview of the boost control mechanism of the Merlin that I know of. It is clear, concise and identifies the operational variables that the boost control mechanism accommodates by design.

It is the appendix of an RR document called "Instructors notes on engine handling in flight'; a high level guide that also covers airscrew variable pitch, range/fuel consumption and other flight mode considerations on engine operation.

Greg's question relates to V1650-7; I have found that the 'V1650-3/-7 service manual' provides a better description of the boost mechanism than the 'V1650-3/-7 overhaul manual'. However the RR document above is the best overview guide of all.

DAI
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gbaddeley



Joined: 03 May 2011
Posts: 2

PostPosted: Thu Sep 08, 2011 12:36    Post subject: Reply with quote

Very many thanks guys;

I have to admit that some of the stuff is way over my head, as we just deal with the oily bits rather than the theory. I'll pass this on to my colleage and thanks again to everyone!

All the best

Greg
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