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Old 04-11-2011, 11:52 AM
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klem klem is offline
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Quote:
Originally Posted by Viper2000 View Post
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klem, I think the consensus is that the Spitfire IIa gives +12 psi boost when the cutout is operated, but since the gauge only reads to +8, you only see +8. However, I note with interest that the "no cockpit" gauge does read to +12, and yet this also only displayed +8 last I checked, so it's not obvious whether or not this is really a bug or a feature.

The Spitfire I notes say that operating the cutout with 100 octane fuel should give +12 psi as well.

I don't know exactly what is supposed to happen with 87 octane for several reasons:
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Really we need to try to find an old set of Notes for the Spitfire I from the 87 octane days to work out what the pre-mod boost control cutout was actually for, given that climbing boost and maximum boost are the same in the Notes I have which came with the CE.

The Hurricane basically had the same engine, as the Spitfire, and therefore I wouldn't expect to see different boost figures.

FTH for +12 was about 10000' at 3000 rpm for early Merlins, and therefore you should be able to get as much boost as you're allowed at 8000.
Thanks for that.

My concern was that in three cases the boost didn't change at all (Spit1s and Hurricane DH 5-20) and the Rotol Hurricane boost barely moved.

Did I miss somewhere that these are 87 Octane and boost isn't effective?
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