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Tallyho1961
03-07-2005, 11:53 AM
On the late model Spitfires, there is a red zone on the boost gauge with room to spare beyond red on the gauge. Does anybody know the significance of this red zone? Does it indicate the powerband? Why is there room beyond?

For that matter, I'm not entirely sure what the boost gauge is. I've noticed the Spits and Hurris have no manifold pressure gauge. Is this the RAF equivalent?

BaldieJr
03-07-2005, 12:06 PM
I think it has something to do with the E-boost given by the ion drive.

Tallyho1961
03-07-2005, 12:28 PM
Please allow Earthlings to respond, my Klingon friend. http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

SS_Bubblehead
03-07-2005, 09:36 PM
The boost gauge is a measure of engine power in Brit planes and hence they have no manifold pressure gauge. I believe for Merlin spits max boost was around 20 psi that was emergency power only and intended for limited use not to exeed five minutes or so. The red band may indicate emergency power. Of course please dont quote me on this as I did not look at a text book.

Heck normal take off power for a spit was around 8 psi boost pressure, and that was also maximum continuous cruise pressure. Selecting 100% throttle for take off is simply not realistic.

OT: Small recommendation if you have FS9, Realair simulations has an addon Griffon engined spitfire that simply kicks axx.

VW-IceFire
03-07-2005, 11:01 PM
Some Mark IX models were boosted to 24lbs of boost pressure. That increased their speeds at various altitudes significantly.

ploughman
03-08-2005, 01:31 AM
Yes, I've read on these forums that the 24lb boost Mk IXs were from the 1944 timeframe. The '44 Mk IXe we have is not this type as it seems to max out at 17lbs of boost (approximately, from memory).

Would a 24lb boosted Mk IX be more of a match speedwise for the later Fw-190s who currently gleefully dissapear into the blue yonder with a string of ever receding Spits on their tail?

lrrp22
03-08-2005, 08:41 AM
IceFire,

Make that virtually *all* ETO Spit IX's operating at +25 lbs boost for the last six months of the war... http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

Spit XIV's were limited to +21 lbs boost.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by VW-IceFire:
Some Mark IX models were boosted to 24lbs of boost pressure. That increased their speeds at various altitudes significantly. <HR></BLOCKQUOTE>

VW-IceFire
03-08-2005, 10:12 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Ploughman:
Yes, I've read on these forums that the 24lb boost Mk IXs were from the 1944 timeframe. The '44 Mk IXe we have is not this type as it seems to max out at 17lbs of boost (approximately, from memory).

Would a 24lb boosted Mk IX be more of a match speedwise for the later Fw-190s who currently gleefully dissapear into the blue yonder with a string of ever receding Spits on their tail? <HR></BLOCKQUOTE>
It would make a small difference. As I've been told, the extra boost pressure translates into better speeds across the altitude spectrum rather than a specifically higher spped. It may make the FW190As at some alts easier to catch but overall it wouldn't have a huge impact.

The Spitfire XIV will be able to run them down at all but the lowest altitudes. There the Tempest V has the job of running them down.

lrrp22
03-08-2005, 03:48 PM
Ploughman,

Here are the speed increases that could generally* be expected for a Spit IXLF boosting to +25 lbs from +18:

0 ft-------+24 mph
2000 ft----+24 mph
3200 ft----+24 mph (+25 lbs M.S. gear FTH)
4000 ft----+20 mph
6000 ft----+12 mph
8000 ft----+5 mph
10000 ft---+10 mph
12000 ft---+21 mph
14000 ft---+24 mph
14400 ft---+24 mph (+25 lbs F.S. gear FTH)
16000 ft---+17 mph
18000 ft---+9 mph
20000 ft---+0 mph (+18 lbs F.S. gear FTH)

*These speeds are for LF IX JL165 which regularly tested ~10 mph slower than other LF IX's and whose engine's Full Throttle Heights were somewhat below other examples.


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Ploughman:
Yes, I've read on these forums that the 24lb boost Mk IXs were from the 1944 timeframe. The '44 Mk IXe we have is not this type as it seems to max out at 17lbs of boost (approximately, from memory).

Would a 24lb boosted Mk IX be more of a match speedwise for the later Fw-190s who currently gleefully dissapear into the blue yonder with a string of ever receding Spits on their tail? <HR></BLOCKQUOTE>