Spit question

[Crumpp]

No extra cooling drag, as the radiators didn't change afaik. I think M&S are talking about a prototype, with possible changes in the intercooler radiator as well.

The extra drag of intakes is lumped under cooling drag.  See page 312.

The later type caused little external drag, but initially air bled around and through the filter even when it was bypassed in flight, leading to a reduction in ram. Later blanking plates were fitted to fully bypass the filter when if flight. see page 281 - 282 of Spitfire the History, which includes tests of several Spitfires with and without the blanking plates. Adding the plates increased full throttle height by 900 - 1300 ft, and increased speeds by 5 - 11 mph.

Yes but that performance is lumped into the evaluation on Pg 312 of the intakes on the Mk IX I would imagine as the trials took place almost a year later.

Facts are there are no "magical" tropical filters.  Adding that feature has engineering consequences.

Does anyone have the manufacture’s guaranteed performance percentages on the Spitfire Marks?  Seems the aircraft exhibits a very wide swath of performance even among the same variant.  I assume that the General Performance specs listed in Shacklady and Morgan are the manufacture’s listed specifications.

It would be nice to get a representative model.  Since real aircraft performance is not as exact as a computer model, one of the first things the community should recommend to HTC is where in that range we should model.

This will prevent some aircraft from being represented by performance figures that are at the upper end of the manufacture’s guaranteed performance percentages while others are modeled at the lower end.  We can avoid gross misrepresentation of Historical engagements that way and end up with better fights.

All the best,

Crumpp

[Kurfürst]

From what Neil posted, British defined 3% variation in max speed for production fighters. Ie a 404mph plane like the spit9lf, was accepted for service from the manufacturer anywhere between 392mph and 404mph.

[Crumpp]

From what Neil posted, British defined 3% variation in max speed for production fighters. Ie a 404mph plane like the spit9lf, was accepted for service from the manufacturer anywhere between 392mph and 404mph.

Yes, I have a copy of that memo.  That seems to be a generalization explaining aircraft performance variations and not anything specific to the Spitfire.

It does list the 3% as an industry standard for fighter performance.  

Focke Wulf, G.m.b.h., Bremen also lists 3% speed variation in the Anton.

I was hoping for something from Supermarine on their design.  It looks to me like the variation is a little wider than 3%.

All the best,

Crumpp

[Guppy35]

First wing bomb racks hung on Spits were by 126 squadron flying from Malta in August 1942 when they hung two 250 pound bombs from racks underneath the outboarf cannon bay on the Spit Vc

Not positive but I believe the first use of the IX with bombs was in April of 44 when they were going after No-Ball targets.  I believe it was a single 500 pounder on the centerline at that point and that it was post D-Day with the intro of the E-wing that the 2 wing hard points were added on the LFIXe and LFXVIe.

Drop tanks development was begun in 39 with the first operational extra tank being the tank they fixed on the port wing of the Spit II that were introduced in late 41.  It didn't work very well and was limited to only a couple squadrons.  The 30,45 and 90 gallon tanks were developed in 1941 but I can't find an exact date of introduction other then it would have been in late 41 or early 42.  The Malta flights with the 90 gallon tanks began in March of 42.

I think the reason our Spit Vb in AH doesn't have the tank is that it is the early 1941 version prior to the tanks being introduced.

[Crumpp]

Guppy,

Do you know Supermarines manufacture’s guaranteed performance percentages for the various Spitfire Marks?

All the best,

Crumpp

[Guppy35]

Originally posted by Crumpp
Interesting Stuff, Guppy.  Essentially then all Spitfires are tropical.  Wonder how they got around the physics and not suffered a cooling drag increase?

 

According to Shacklady and Morgen it went from 8% to 12% with new filters in Spitfire Mk IX.  The Spitfire MK VIII had a "universal" filter but it still seems to effect performance as you are hanging extra cooling drag on the aircraft and was the same on used on the Spitfire Mk IX AFAIK.

However it does not answer my question:



Do you know the answer?

All the best,

Crumpp

The filters had shutters that could be opened or closed from the cockpit for filtering or not filtering the air.  This was true on the large Spit Vc tropical intakes and on the streamlined version used on the VIII, IX and XVI

[Crumpp]

On page 244 it shows the operation of the large tropical filter on the Spitfire.  It looks to me like you could open and close the intake but you could not bypass the filter element in flight.

The German systems closed the intake forcing air through the filter.  When the aircraft was in flight, the intake would be opened and the filter bypassed.

This seems to be a feature in the "universal" intake found on the later Mark Spitfires but does not seem to be the case in the earlier tropical filter.

All the best,

Crumpp

[Guppy35]

Originally posted by Crumpp
On page 244 it shows the operation of the large tropical filter on the Spitfire.  It looks to me like you could open and close the intake but you could not bypass the filter element in flight.

The German systems closed the intake forcing air through the filter.  When the aircraft was in flight, the intake would be opened and the filter bypassed.

This seems to be a feature in the "universal" intake found on the later Mark Spitfires but does not seem to be the case in the earlier tropical filter.

All the best,

Crumpp

Yep, my mistake, I thought you meant whether it could be closed or opened similar to the way the 109 had set up.  

Always dangerous when I start delving into the technical side of stuff.  Guess that's why I ended up with a History and English degree and not engineering or math

[Kurfürst]

Thanks for the answer, Guppy, though it's a bit strange if no IX would fly bombing sorties for almost 2 years in service. OTOH their mission profile was probably high escort until 1944 when they became numerous enough to take the other tasks from the Vs.

When did the E-wing appeared in production, August-September 1944? How widespread it was?

Note on the Sandfilters on the 109s, it operated the way Crumpp describes it, the shell could be opened/closed from the cocpit with a bowden. It was a simple, easily added device to filter the dust out near the ground. According to specs I have, it came with a -10kph speed penelty near SL, and -200m cost in FTH. Pretty typical for these filters, see the MkV tests with iceguard, there's similiar penalty in FTH.

[Kev367th]

'e' wing was used on  -
all the XVI's
retrofitted to a number of XIVs and IXs.

From the F.21 onwards I believe the wing was a new design, standard fit was 4 x 20mm.

Didn't know about this one though -
'd' wing - long-range wing for reconnaissance versions with armament replaced by fuel tanks

[Kurfürst]

Can it be confirmed that XVIs only came with E-wing ? One Brit datasheet I have lists them with either 4x,303 or 2x,50...

[Guppy35]

Originally posted by Kurfürst
Can it be confirmed that XVIs only came with E-wing ? One Brit datasheet I have lists them with either 4x,303 or 2x,50...

I don't have an exact date on the E wing.  They appear in photos of Spit IX/XVIs post D-Day.  The Spit pilot's logbook I have, shows his first flight in his E wing Spit XIV as mid July 44.  He designated it it specificallly a Spit XIVe.

From the official RAF Spit IX/XVI maint manual.  Note how the E wing is designated on the IX as well as the type, ie; LF, F, HF, while there is only a single line for the XVI, meaning it was only built as an LF and with only the E wing. as it lists only the Merlin 266 and the armament of 2 20mm and 2.5mg

Also interesting to note that there is no FIX listed with an E wing.  Another reason any call for it on our FIX in AH is wrong

[Squire]

For the XVI, they entered service in October 44 with 2nd TAF, by which time the E wing was standard in production (6/44). I doubt you will find any photos or refs to operational XVIs with C wing armament.  I understand the early versions tested by the AFDU in the summer of 44 had C wings, and docs probably show that.