Spit Vb Boost

[TonyJoey]

I recently got a book claiming the Spit Vb ran full throttle at +18lbs boost. In AH the boost only goes to 9, but goes to negative 9, shouldn't it just be minimum 0 and max. +18, or am I mistaken. I am very curious, as I have developed a liking of the SpitV after reading the book.

[Jabberwock]

The various Merlin engine marks of the Mk Vs (Merlin 45/46/47/50/55) were rated at different levels over the course of the aircraft's service life.

The Merlin 45 that the Mk V started life with was initially rated at +9 lbs, then uprated to +12 lbs, then to +15 lbs and finally +16lbs. This happened over the course of about 2 years.

The difference in horsepower is quite impressive. From ~1,135 hp at 18,000-19,000 ft to ~1,480 hp at about 14,000 ft.

The later ‘M’ Merlin 40/50 engines, with a cropped (smaller diameter) supercharger impeller, put out up to 1,585 hp at +18 lbs boost, but at very low altitude, around 5-6000 ft for full throttle height (the highest altitude that maximum boost could be sustained).

EDIT: Its important to note that a later, higher boost rated Spitfire Mk V would not have a higher top speed. As the additional power is all produced below the +9lbs full throttle height, all the gains in speed would happen below that altitude. Top speed is not just about total power, but power delivered at altitude.

A +16 lbs rated Spitfire Mk V would still only do about 370 mph at best altitude, but it would be about 25 mph (40 kph) faster at lower altitudes and perhaps 500 ft/min better in a climb.

[Wingnutt]

In AH the boost only goes to 9, but goes to negative 9, shouldn't it just be minimum 0 and max. +18, or am I mistaken.

at lower engine settings you actually pull a vacuum in the intake manifold, hence the need for negative readings of "boost".  Just like turbo equipped car engines of today.

[Guppy35]

The AH Spit Vb is an early Vb so it's not the later uprated engine and boost.

[jocko-]

How about a Spit Vc for AH2?  I'll even accept a Vc with a Vokes filter if it means 240 Hispano rounds 

[Krusty]

Fly a spit9. It's like 9 mph faster on the deck and has the rest of what you wish.

[Noir]

How about a Spit Vc for AH2?  I'll even accept a Vc with a Vokes filter if it means 240 Hispano rounds 

Thats what we used to have, and the spit9 was useless in the arena. Remember the good old Spit V and N1K days ?

[Kev367th]

Thats what we used to have, and the spit9 was useless in the arena. Remember the good old Spit V and N1K days ?

The old LF Vc was a blast.

[Noir]

The old LF Vc was a blast.

the fact that it used to beat the 9 model at low to medium alt was made it the most popular ride. I used to complain a lot about the N1K tho, even after the fix, and I still do in regards of the energy retention...how long a N1K can maintain 400mph+ after a dive seriously ? But that's another story, now we've got the spit16 to complain about 

[Kazaa]

The old LF Vc was a blast.

Yeah it was! I'm not sure why HTC feel the need to gimp our Spitfires.

[SmokinLoon]

Yeah it was! I'm not sure why HTC feel the need to gimp our Spitfires.

Supposedly, I do believe it is their attempt to make things "more accurate" seeing as how most of the Spit V models had the 60rd drum vs the 120rd belts for ammo feed devices.  Evidently HTC did the same with the 109G-10 as well and revmoved it altogether and added in other more accurate representations of the 109 series?

If one wants the "old" AH2 Spit Mk V, then may I suggest the Seafire?  Are they not the exact same aircraft albeit the Seafire's reinforced landing gear and tail hook for carrier landing???  I am under the impression that they are and were the exact same aircraft (frames, engines, etc). 

[Kev367th]

Supposedly, I do believe it is their attempt to make things "more accurate" seeing as how most of the Spit V models had the 60rd drum vs the 120rd belts for ammo feed devices.  Evidently HTC did the same with the 109G-10 as well and revmoved it altogether and added in other more accurate representations of the 109 series?

If one wants the "old" AH2 Spit Mk V, then may I suggest the Seafire?  Are they not the exact same aircraft albeit the Seafire's reinforced landing gear and tail hook for carrier landing???  I am under the impression that they are and were the exact same aircraft (frames, engines, etc). 

Nope -
When it was found out the Spits were being remodelled there was a Spit lineup wishlist created.
To provide a range of Spits covering specific time spans a Vb was suggested instead of the Vc. Don't know if HT and co used the wishlist at all, but it seemed to be almost granted to the letter.

Most of the V's ended up the 'c' wing, not the 'b' wing.

Seafire - If our model existed it is very rare, i.e. seafire IIc with a Merlin 45. If it is a Merlin 45 based Seafire it should only have 60 rounds per gun as they were a limited number of converted RAF Vb's.
More correctly it seems to be a Seafire IIb with a 'c' wing, very strange.

[Krusty]

Keep in mind the spit5 didn't have +18 boost for long. It was right around when AH2 was introduced, or something like that. Before that point it had the "normal" boost that it was reduced back to.

Makes no sense in having a 1943 SpitV while having a 1941 109F-4....

It's about balances, planesets for scenarios, matchups, etc.

[Kev367th]

Keep in mind the spit5 didn't have +18 boost for long. It was right around when AH2 was introduced, or something like that. Before that point it had the "normal" boost that it was reduced back to.

Makes no sense in having a 1943 SpitV while having a 1941 109F-4....

It's about balances, planesets for scenarios, matchups, etc.

Thought old Vc was always 18lbs?

Anyway yup -

1940 - Spit Ia
1941 - Spit Vb
1942 - Spit IX
1943 - Spit VIII
1944 - Spit XVI, XIV

Which is what we suggested in the wishlist, with only 1 difference - we asked for either a 25lbs XVI or a 21lbs XIV to fill the 1945 slot.

Whats missing is 1945 - Could only be either a max boost XVI or XIV or the F.21

[edit] Thinking about it - we might have asked for a cut down bubble hood XIV, just to make it different.

[Guppy35]

Thought old Vc was always 18lbs?

Anyway yup -

1940 - Spit Ia
1941 - Spit Vb
1942 - Spit IX
1943 - Spit VIII
1944 - Spit XVI, XIV

Which is what we suggested in the wishlist, with only 1 difference - we asked for either a 25lbs XVI or a 21lbs XIV to fill the 1945 slot.

Whats missing is 1945 - Could only be either a max boost XVI or XIV or the F.21

[edit] Thinking about it - we might have asked for a cut down bubble hood XIV, just to make it different.

Our mistake when we got into the discussion about the Spits was we were reasonable, trying to look at it from the scenario, what's fair etc.  We suggested LFXVI instead of LFIX just to try and cover that 44-45 timeframe.  Seems like we figured it would mean less modeling time to keep the XIV a high back too.  Again, being reasonable in our thinking.  I do recall it was one of us who suggested the V being essentially taken back to the Vb and 1941 too.

We should have kicked, stomped and been demanding!

Of course we knew it was HTC's call in the end