Any good explanation about "new" spit diving ability

[GODO]

The following tested planes cant catch them (SpitV, Seafire or Spit IX) until dive ends starting at 150mph: P47D40, 190A5/A8/F8, F4U1D/C. Tests were done from 5, 10, 15 and 20k and leveling at sealevel (diving near vertical), every plane 100% fuel and minimum ammo load. SpitV vs 190D9 ended in a draw.

[SELECTOR]

oh boy

[Karnak]

When running the reverse tests do the Spit's overtake the non-Spits?  

Remember, the Spitfire's top dive speed is higher than any other fighter's.  If the Spit has enough of a head start it will reach those speeds and then no aircraft in AH (barring the 262 or 163) can catch it.  It is just a matter of whether or not the Spit's head start is enough to overcome the initial acceleration deficit and as F4UDOA's "Most over rated flight characteristics" thread pointed out, the differences are not very significant when starting from the same speed.

Put it this way, why would an Fw190D-9 begin a chase of a Spit V at 150mph?  The only way that would happen is if the Fw190D-9 pilot had messed up.  If the Spit V is cruising at, say, 260mph and is bounced by an Fw190D-9 odds are the Fw190D-9 will have at least a 150mph advantage at the start.  Will the Spit V still be able to escape in a dive?

[Widewing]

Originally posted by GODO
The following tested planes cant catch them (SpitV, Seafire or Spit IX) until dive ends starting at 150mph: P47D40, 190A5/A8/F8, F4U1D/C. Tests were done from 5, 10, 15 and 20k and leveling at sealevel (diving near vertical), every plane 100% fuel and minimum ammo load. SpitV vs 190D9 ended in a draw.

That doesn't surprise me considering that Spitfires were capable of Mach 0.85 without breaking up. P-47s could manage about Mach 0.83, with the F4U and 190 right there too. I'm not talking about Critical Mach, I'm referring to terminal velocity, which means being deep into compressibility.

My regards,

Widewing

[Crumpp]

Huh?  

So now the spitfire can outdive any plane too?  Come on.  Sure their are some pretty high Mach numbers quoted for the Spit.  

It was a post war model Griffon from what I heard AND I know the pilot almost did not make it.  The plane had to be scrapped after the flight.

FW-190 were only tested to mach .80.  At that mach number they could still be flown with "appreciably higher than normal but still acceptable control forces AND recovered without damage to the plane.  

The Spitfire's current dive modeling is OFF and does not accurately reflect it's true abilities.

Crumpp

[Urchin]

I don't think the modelling is off, I think people aren't taking net lag into effect.  

I ran these dive tests online with the results that the Spit 5 would run down a 190A5 in a dive from any alt.  Then we switched planes... and the 190A5 would run down the Spit 5 from any alt.  

So I took it off-line and recorded top speed at the bottom of the dive, the 190A5 had a ~20 mph advantage over the Spit 5 in a dive from 5k.  Don't think I tested it from higher than that, the original post might be floating around here somewhere, but it was in one of the AH2 forums so maybe not.

Do the tests offline, record the top speed at the deck when you pull out.  Hell, if you have a stopwatch (and a willing assistant), time the seconds it takes for the planes to accelerate through a set speed interval in a 0-G dive (which is how I did my tests).  

Basically doing a test side by side with another guy in-game is going to give you screwy results.  That is just the way it works, with netlag and all.

[Crumpp]

Karnak,

Found some interesting information when I dug into this.  The data just did not match up with common tactics used by the LW against the Spitfire.

http://www.fourthfightergroup.com/eagles/spit9v109g.html

The 750kph IAS limit found in the pilots manual for the 109 which the RAF based it's limits off of for the Spit/109 dive test is wrong.

After the fatal crash of Dr. Jodlbauer and a near crash by Heinrich Baeuvais in early 1941 in the 109 the RLM abandoned high speed testing and the plane was given back to Messerschmitt to determine the safe diving speed.  Messerschmitt shelved the tests and arbitrarily set the "do not exceed" dive limit at 750 kph.  After front line experience and a series of accidents, 20 in one month, the investigations had to be resumed in January 1943.

During those trials a Bf-109F2 was dove to 906 IAS kph (563 mph), mach .80 with aileron reversal and elevator reversal.  It was safely recovered at 6 g's.

The result of these trails was the increased height of 135mm on the vertical stabilizer.  This prevented elevator reversal.

The test Aircraft was a BF-109F-2 WrkN 9228, code TH + TF flown by Lukas Schmid.


The Aircraft could be dove to 890 kph IAS (553 mph) with no ill effects on the controls other than the extremely heavy control forces all Me-109's experienced.  This became the new safe diving speed.

During the LW tactical trials of a Bf-109F2 against a FW-190A2, the FW190 out dove the BF-109 and "rapidly pulled away"

Any 109 or 190 pilot with a Spit on his six should be able to push the nose down and leave the Spit setting.

Crumpp

[Karnak]

Crump,

What has that to do with anything?

In any case, .80 mach is still lower than .85 mach.

[Crumpp]

Facts are Karnak,

The Merlin powered spits didn't have that high a mach number and couldn't outdive either the 109 or the 190.

Crumpp

[Crumpp]

Infact,

20 MPH IAS is way off.  The true difference is on the order of 110 mph IAS according to the RAF's dive speed limits of the Spitfire Mk IX with +25 lbs boost for the 109G and even greater for the 190.

It should take a heck of alot of net lag to overcome that difference.

Crumpp

[MiloMorai]

(1) The maximum permissible indicated airspeeds in the different heights are not being observed and are widely exceeded. On the basis of evidence which is now available the speed limitations ordered by teleprint message GL/6 No. 2428/41 of 10.6.41 are cancelled and replaced by the following data:

Up to 3 km   (9,842 ft.)   750 km/h.   (466 m.p.h.)
At 5 km   (16,404 ft)   700 km/h.   (435 m.p.h.)
At 7 km   (22,965 ft)   575 km/h.   (357 m.p.h.)
At 9 km   (29,527 ft)   450 km/h.   (280 m.p.h.)
At 11 km   (36,089 ft)   400 km/h.   (248 m.p.h.)

.......These limitations are valid for the time being for all building series including the Me 109 G. A corresponding notice is to be placed upon all air-speed indicators in aircraft.

.......These limits are also to be found in Vorläufige Fluggenehmigung BF 109 G-2 and G-6


Flying Limitations of the Spitfire IX (from Pilot's Notes)
Maximum speeds in m.p.h I.A.S.
Diving (without external stores), corresponding to a Mach No. of -85:

Between      S.L. and 20,000 ft.   - 450
      20,000 and 25,000 ft.   - 430
      25,000 and 30,000 ft.   - 390
      30,000 and 35,000 ft.   - 340
Above      ..................35,000 ft.   - 310

Only under 10,000ft does the 109 have a greater dive speed.

[Karnak]

Originally posted by Crumpp
Infact,

20 MPH IAS is way off.  The true difference is on the order of 110 mph IAS according to the RAF's dive speed limits of the Spitfire Mk IX with +25 lbs boost for the 109G and even greater for the 190.

It should take a heck of alot of net lag to overcome that difference.

Crumpp

Where are you getting this?  I don't see any data backing that up.  You seem to be just arbitrarily stating that Merlin Spits didn't have enough power.

Keep in mind that the Spit that did .89 mach only did so because it's propellor shattered.  E.g., it had no power.

[Crumpp]

For the 190 Tactical Trials

http://www.odyssey.dircon.co.uk/Spitfire9v190.htm

For the 109.

max. Mach 0,805@7.0km
max. TAS 906km/h@5.8km
max. IAS 737km/h@4.5km
Even more interesting is the fact that they tried different positions of the trimming. With the wrong trim set - the one for cruising at high altitude it was not possible to pull out of the dive just by using the stick. They needed to use the trim wheel to recover the plane from the dive. This happened in such violent manner that the test pilot had to push the stick foreword to be not blacked out...
If the trim was set to +1.15° it was possible to recover without using the trim wheel - both flight paths, with and without the trim wheel, are very similar. So even with the concrete stick the limiting factor seems to be the pilot.
Also interesting in the dive the canopy iced, also the mechanism of the trim, so it was not possible to set it smooth, but in \"jumps\", but it was still adjustable...
- Source: Hochgeschwindigkeitsversusche mit Me 109, Messerschmitt AG, Augsburg.

http://109lair.hobbyvista.com/techref/structures/tails/109.05e43_report/05e43-p1.htm


You can find the full report of the high speed trials conducted in 1943 in "Messerschmitt Bf-109F-K Development, Testing, Production" by Willy Radinger and Wolfgang Otto.  It begins on Page 15.

Crumpp

[Crumpp]

My apologies,

It is not listed as IAS or TAS in the book.  I ASSuMEd that it was IAS.

Milo is correct, under 10,000 feet the 109 does outdive the Spit MkIX.  I believe the 190 Pilots Handbook has the dive speed listed.  ANOTHER thing to check when I get them back from being translated.

Crumpp

[VO101_Isegrim]

Sorry but what does the highest Mach numbers achieved in single tests with often modified, unarmed etc. planes matter in dive acceleration ? It might give you some very basic clue about the terminal Mach speed of these airfcraft, with a large margin of error, considering all of these these were measured with instruments prone to a large margin of error.

Similiarly, what does the laid down safety dive limits in the manuals has to do anything with the fighters ability to dive ? It`s a _safety limit_, not an indicator of how fast a fighter will accelerate in dive!

I can only speak for the 109, but those very conservative limits were very often exceeded with no damage to the plane by a considerable margin In the 109`s example, the dive speed limit is 750 km/h IAS (which was increased to 850 km/h or 528mph IAS on the 109K, even with gunpods added) - do you really expect something horrible will happen at 760, 770 km/h IAS? Nope, there`s plenty of built-in safety margin there - for example, in the mentioned Lukas Schmidt test those margins were exceeded by 100 km/h on avarage with no damage to the plane. . I am sure such exceedings could be done on most other planes as well, most of the time it would not cause critical damage. These limits only show how far the manufacturer was willing to give a guarantee. Take WW2 subs for example - manufacturers 'safe depth' limit was 90m. In real life, sub commanders could dove their boat to 340m and did come back from there.

The ability to accelerate in a dive can be determined from the design and the did comparitive dive trials. None of those will tell you the Spit should be something of a great diver - it`s a large drag machine of medium-light weight, with relatively low wingloading. None of these will it in a dive. And this theory is fully supported by all dive tests I have seen with the Spit pitted against other machines - P-47s, P-51s, FW 190s, Bf 109s -  DID outdive the Spit all the dive, whatever Mark we speak of. Mk I, Mk V, Mk IX was outdived, even the Mk XIV was outdived initially by the worst matchup 109G-6 with gunpods and reduced engine power.