Spitfire speed at sea level - V 4.5 patch

[Talisman]

Hi Folks,

Testing the V 4.5 patch Spit 1a 100 Octane at sea level, I am finding it slower and I am also finding this a noticeable negative factor in low level combat too.

This is my test:

Establish cruise at sea level. Accelerate to best speed with BCO off (the resulting speed is lower than pre-patch for me). Engage BCO (reduce power to do so) and accelerate to best speed (the resulting speed is lower than pre-patch for me and the acceleration to it appears rather slow).

In short, I have yet to get to 310 mph unless with the nose down and I find this aircraft slower at lower altitude in combat.

Is anyone else finding the same? Perhaps it is just me and a strong headwind has been added in some of the standard quick missions that I used to test with.

Perhaps this is an example of the new engine mechanics, but if it is then something may have been missed regarding the 310 mph sea level speed.

Thoughts anyone?

Happy landings,

56RAF_Talisman

[BOO]

Hello Talisman

with the rads in at 40%, the prop pitch reduced to 75-80% and conducting the same test I can get the IAS in cockpit to 300. In wonder woman view the dial is at 305.

The label readout nearly always reads to the lower full 10 mph (so if you are doing 298mph IAS itll show 290)

I'm not sure which test results are being compared but I also understand that the effect of the armoured windscreen is to take about 6mph off over the non armoured glass early types.

I don't personally feel that the new FM is hampering the spit in any way in lower level combat.

[Kalthios]

Prevailing winds do not effect IAS.

At 7k ft asl and 70% fuel, 2800 rpm, radiator open enough to stop overheating:

Ia 100 oct - 300 mph
IIa - 270 mph

same settings at 14k feet:

1a 100 oct - 270 mph
IIa - 275 mph

I haven't learned engine management in the 109, but did a quick speed test with the 109/4N, radiators fully open, 2600 rpm, full throttle, no WEP:

@ 7k feet (2133 meters)
109/4N - 292 mph (470 kph)

@ 14k feet (4267 meters)
109/4N - 285 mph (460 kph)

[Talisman]

Hello Talisman

with the rads in at 40%, the prop pitch reduced to 75-80% and conducting the same test I can get the IAS in cockpit to 300. In wonder woman view the dial is at 305.

The label readout nearly always reads to the lower full 10 mph (so if you are doing 298mph IAS itll show 290)

I'm not sure which test results are being compared but I also understand that the effect of the armoured windscreen is to take about 6mph off over the non armoured glass early types.

I don't personally feel that the new FM is hampering the spit in any way in lower level combat.

Hi Boo,

Thanks for getting back. Interesting that you get the same IAS and wonder woman view speed result as I do with this test. Thing is, prior to the patch, wonder woman view clearly showed 310 mph and the needle on the cockpit ASI gauge was much higher before than it is now at top speed (this is very noticeable). I know how to fly the pre-patch CloD Spit fast and I know how it used to perform at sea level (4000+ hours). It has been stated in previous forum discusions going years back that 310 mph is the correct speed for the Spit 1a 100 Octane we have modelled. When you have a 109 on your tail (or a 109 trying to get away), that 5 mph makes all the difference. Also, if this speed has been shaved off, how might it be effecting performance across the range?
Top speed without BCO is not looking good either.

Thanks again and happy landings,

56RAF_Talisman

[Talisman]

At 7k ft asl and 70% fuel, 2800 rpm, radiator open enough to stop overheating:

Ia 100 oct - 300 mph
IIa - 270 mph

same settings at 14k feet:

1a 100 oct - 270 mph
IIa - 275 mph

Also, prevailing winds do not effect IAS.

Hi Kalthios,

Thanks for getting back. Spit IIa not looking good either, with or without BCO, but I can get more than 270 mph with BCO on at sea level.
I am begining to think that some fundamental change, perhaps an error, has taken place regarding the Spitfire performance in terms of level speed.

Happy landings,

56RAF_Talisman

[Tibsun]

Every aircraft is slower as flaps doesn't give you additional 5 mph speed anymore.

If you take a look at Kalthious post, you see that the Ia 100 oct is doing 305 mph thats 13mph faster than the E4 - wait for it .... N with the db601 N engine!!! (He clearly missed the 5mph) and what about the E1 - E3 wich historically should be also a good comparision against the Spit 1a 100oct so don't say the Spit is too slow below 7k feet.

109s where always faster above 4km/14k feet where the fixed altitude bug applies, now 109's can use their strength at higher altitudes.


Your negative combat factor is you are turning too hard. And you clearly didn't try out the 109's, especially the non N or B version of it, wich are not available in every map.

[Kalthios]

It would be great if an experienced 109 pilot could test out top speeds at 2133 meters and 4266 meters and report back, the various models would be nice as well.

So I flew the E4s at 7k feet, trimming the rads as best I could, with autopitch:

E4B
No WEP: 298 mph (480 kph)
WEP: 308 mph (495 kph)

E4N (WEP would not activate):
No Wep: 301 mph (485 kph)

E4
No WEP: 292 mph (470 kph)
WEP: 298 mph (480 kph)


Still would like experienced 109 pilots data.

[Tibsun]

Try it all with open rads in first place?

And yes 109 was faster above 4k so what's your point there?

The Spit 1a 100oct is faster than all of them with atleast 5km/h below 10k feet also with experienced pilots and top notch 109s.

Spit1a 100 oct is faster and turns better, almost in any kind it is outperforming the 109 and your beloved B version below 10k feet, yet you are still complaining.

Try it out yourself you are seeing things wich aren't there.


EDIT: There we go, doing more flap is not really possible and changing speed by 1km/h at most. You've got your results. Turns better and is faster than the best top notch 109. What else do you want?

[Kalthios]

Went back and tested the Ia 100 oct again at 7k feet, 198 kg of fuel. Top speed of 295 mph.

[Talisman]

Every aircraft is slower as flaps doesn't give you additional 5 mph speed anymore.

If you take a look at Kalthious post, you see that the Ia 100 oct is doing 305 mph thats 13mph faster than the E4 - wait for it .... N with the db601 N engine!!! (He clearly missed the 5mph) and what about the E1 - E3 wich historically should be also a good comparision against the Spit 1a 100oct so don't say the Spit is too slow below 7k feet.

109s where always faster above 4km/14k feet where the fixed altitude bug applies, now 109's can use their strength at higher altitudes.


Your negative combat factor is you are turning too hard. And you clearly didn't try out the 109's, especially the non N or B version of it, wich are not available in every map.

Steady on Tibsun. I started this thread to focus on the Spitfire. If you want a thread about another aircraft type or something else than please start a new thread. Please don't let this thread get hijacked for other purposes.

I am confused by your response. Are you privy to some information that says that all aircraft will be slower than historical speeds?

I don't see why the fixed altitude bug applies to the historical top speed of Spit at sea level. Particularly as careful effort was made in the past by TF to get the top speed at sea level historically correct for the Spitfire. I am sure that TF have not suddenly thrown historically correct data out of the window and suddenly decided that the Spitfire must be slower.

Also, please don't pressume to know how I fly; I have not mentioned turning at all, so I am not sure why you think it relevant and I do not appreciate your diversions from the main topic.

Please stay on topic and don't make this personal. Thank you.

Happy landings,

56RAF_Talisman

[Talisman]

It would be great if an experienced 109 pilot could test out top speeds at 2133 meters and 4266 meters and report back, the various models would be nice as well.

So I flew the E4s at 7k feet, trimming the rads as best I could, with autopitch:

E4B
No WEP: 298 mph (480 kph)
WEP: 308 mph (495 kph)

E4N (WEP would not activate):
No Wep: 301 mph (485 kph)

E4
No WEP: 292 mph (470 kph)
WEP: 298 mph (480 kph)


Still would like experienced 109 pilots data.

Please Kalthios, this thread is about the Spitfire Mk 1a 100 Octane top level speed at sea level. I would very much like for this thread to stay on topic. Thank you very much.

Happy landings,

56RAF_Talisman

[Kalthios]

No worries, I'll take my science elsewhere, Cheers.

As for the Ia, as I said previously:

"Went back and tested the Ia 100 oct again at 7k feet, 198 kg of fuel. Top speed of 295 mph. "

The other speed figures put the speed of the Ia into perspective. I started a top speed thread in the Flight School forum if anyone is interested in perusing and contributing.

Historically, I remember reading that the Spitfire Ia went 360 mph and the 109 340 mph, here is the source: http://www.spitfireperformance.com/spit1vrs109e.html

[RAF74_Buzzsaw]

No worries, I'll take my science elsewhere, Cheers.

As for the Ia, as I said previously:

"Went back and tested the Ia 100 oct again at 7k feet, 198 kg of fuel. Top speed of 295 mph. "

The other speed figures put the speed of the Ia into perspective. I started a top speed thread in the Flight School forum if anyone is interested in perusing and contributing.

Historically, I remember reading that the Spitfire Ia went 360 mph and the 109 340 mph, here is the source: http://www.spitfireperformance.com/spit1vrs109e.html

Hello Kalthios

With all due respect, some science for you:

Aircraft airspeed measuring devices depend on pressure to get their readings... they read in Indicated Airspeed... IAS.

IAS is not the same as True Airspeed... TAS... unless the aircraft is at sea level.

That is because air pressure decreases with altitude.

To determine TAS at altitudes above sea level, you need do a calculation.

TAS=IAS/sqrt(delta)

where Delta=ratio of air density to ISA SL density
=288.15/(T+273.15) * (P/1013.25)

and P= Ambient pressure in HPa(mB)
T= ambient temperature in degrees celsius

In your example, i.e. 295 mph at 7000 ft, the actual True Airspeed is approx. 337 mph.

My suggestion is you do some further investigation:

https://en.wikipedia.org/wiki/True_airspeed

Regarding your claims for top speed for the 109's:

I have not seen anywhere 340 mph listed for the 109E... not even by French or British in their captured tests.

The 109E-3 which was used in these captured tests was crashlanded... had a bent prop, and had to be equipped with a different non-standard prop... so there were inaccuracies there.

Still, the French got 570 kmh as their maximum TAS at altitude... that is 354.5 mph.

The same aircraft was then turned over to the British, by that time not running very well... it tended to overheat, and the British got max speed at alt of 348 mph.

German documents tend to agree fairly closely with the French results, slightly higher.

But of course, aircraft out of a factory can vary in maximum performance results by as much as + or - 5% depending on what serial number you are testing.

[Kalthios]

Buzzsaw, let's talk about it in the Flight School forum, don't want to hijack a thread.

[Tibsun]

Steady on Tibsun. I started this thread to focus on the Spitfire. If you want a thread about another aircraft type or something else than please start a new thread. Please don't let this thread get hijacked for other purposes.

I am confused by your response. Are you privy to some information that says that all aircraft will be slower than historical speeds?

I don't see why the fixed altitude bug applies to the historical top speed of Spit at sea level. Particularly as careful effort was made in the past by TF to get the top speed at sea level historically correct for the Spitfire. I am sure that TF have not suddenly thrown historically correct data out of the window and suddenly decided that the Spitfire must be slower.

Also, please don't pressume to know how I fly; I have not mentioned turning at all, so I am not sure why you think it relevant and I do not appreciate your diversions from the main topic.

Please stay on topic and don't make this personal. Thank you.

Happy landings,

56RAF_Talisman

Sorry if I have mixed it up with Kalthious post and 109s.
It was some kind of a reply to you with taking his post as example.
If you say it's negative in combat and at the same time you say it's not about turns and you don't compare to other planes, well sorry if I confuse up things here, I thought it was ment against the counterparts.
As Boo said, it was mentioned somewhere here that the Spit without armor and with dehavilland prop was doing 312mph but the 1a 6mph less - now it is doing exactly this, it was also mentioned that previoulsy all aricrafts where too fast.
Now they aren't anymore and you can't achieve it anymore by adjusting rads close to overheat. I wish I could get a bit more out of it when going hardcore, but well you can't do it to any plane anymore.

As for me, this data is not from me, and I'd like to see the source of the Spit 1a 100oct doing 310mph with CSP and armour. I always like to have them as historical as possible. (Now to say, not every aircraft test might reflect the historical perfomance)

[RAF74_Buzzsaw]

I will post this reply here as well... It is posted originally in another thread.

------

Both Blue and Red types are slower at Sea Level than in TF 4.312.

That is partly historical adjustment and partly the fact there has to be some balancing to make sure the maximum altitude climb ceiling of the aircraft types is accurate.

Even with that considered, 305 mph for the Spit IA 100 octane is not incorrect... although you see higher speeds on certain British tests with 100 octane, it is important to understand those tests were done with a Spit I, an aircraft which did not have the bulletproof windshield fitted, and the windshield typically reduced top speed due to its considerable drag. (it was fitted outside the cockpit instead of inside, as was the case with the Spit VC and later types) The loss of speed due to drag when the windshield was fitted outside was calculated in testing by the RAF at between 6-10 mph. Also a Spit I had a different prop, a prop designed for better speed instead of climb... the Rotol prop on the IA 100 octane was focused on improved climb. (so slower)

The important thing players will discover about 4.5 is the Spits are faster relative to the 109's at sea level and lower altitudes when compared to 4.312. They are slower at higher altitudes. Both results are historical.

I will not comment any further about performance... except to say the aircraft are more accurate than 4.312.

[Talisman]

I will post this reply here as well... It is posted originally in another thread.

------

Both Blue and Red types are slower at Sea Level than in TF 4.312.

That is partly historical adjustment and partly the fact there has to be some balancing to make sure the maximum altitude climb ceiling of the aircraft types is accurate.

Even with that considered, 305 mph for the Spit IA 100 octane is not incorrect... although you see higher speeds on certain British tests with 100 octane, it is important to understand those tests were done with a Spit I, an aircraft which did not have the bulletproof windshield fitted, and the windshield typically reduced top speed due to its considerable drag. (it was fitted outside the cockpit instead of inside, as was the case with the Spit VC and later types) The loss of speed due to drag when the windshield was fitted outside was calculated in testing by the RAF at between 6-10 mph. Also a Spit I had a different prop, a prop designed for better speed instead of climb... the Rotol prop on the IA 100 octane was focused on improved climb. (so slower)

The important thing players will discover about 4.5 is the Spits are faster relative to the 109's at sea level and lower altitudes when compared to 4.312. They are slower at higher altitudes. Both results are historical.

I will not comment any further about performance... except to say the aircraft are more accurate than 4.312.

Thank you for the explanation Buzzsaw.

Happy landings,

56RAF_Talisman

[Spindinio]

I will post this reply here as well... It is posted originally in another thread.

------

Both Blue and Red types are slower at Sea Level than in TF 4.312.

That is partly historical adjustment and partly the fact there has to be some balancing to make sure the maximum altitude climb ceiling of the aircraft types is accurate.

Even with that considered, 305 mph for the Spit IA 100 octane is not incorrect... although you see higher speeds on certain British tests with 100 octane, it is important to understand those tests were done with a Spit I, an aircraft which did not have the bulletproof windshield fitted, and the windshield typically reduced top speed due to its considerable drag. (it was fitted outside the cockpit instead of inside, as was the case with the Spit VC and later types) The loss of speed due to drag when the windshield was fitted outside was calculated in testing by the RAF at between 6-10 mph. Also a Spit I had a different prop, a prop designed for better speed instead of climb... the Rotol prop on the IA 100 octane was focused on improved climb. (so slower)

The important thing players will discover about 4.5 is the Spits are faster relative to the 109's at sea level and lower altitudes when compared to 4.312. They are slower at higher altitudes. Both results are historical.

I will not comment any further about performance... except to say the aircraft are more accurate than 4.312.

Sadly they are not more accurate and 305mph is incorrect for a Battle of Britain aircraft. I would have written this direct into the TF forum but unfortunately the access wasn't granted following our meeting, so I had to pick up this point here.

You are correct that the highlighted part is true. The armoured shield DOES affect the speed by an estimated 6mph (A.&A.E.E or RAE didn't mention "6-10mph", only 6mph) and the aircraft also had a different prop. This is correct for the tested aircraft

Early production Spitfire Is achieved top level speeds is excess of 360 mph. Trials by the Aeroplane and Armament Experimental Establishment (A.& A.E.E.) at Martlesham Heath and Boscombe Down obtained maximum level speeds of 362 mph for Spitfire I, serial number K.9787, 367 mph for K.9793, and 364 mph for L.1007. These aircraft, however, do not represent the condition of those that first fought against enemy fighters over Dunkirk in May 1940. A number of improvements were necessary to make the Spitfire ready for war. The addition of a bullet proof windscreen was one of those improvements, however, it cost about 6 mph and resulted in a maximum top level speed ranging from 355 to 360 mph during the Battle of Britain

As I pointed out to Mystic Puma long before 4.5 release and this information was passed on through the forums and you gave back the same answer as in your post above.

In reply I sent Mystic Puma the following information and he posted that into the forums but it appears to have been missed or ignored......further on in the same page

Spitfire Mk. I serial No. N.3171 first flew on 10 November 1939 and was delivered to A.& A.E.E. at Boscombe Down for flight trials on 16 November 1939. It was equipped with a Merlin III engine, Rotol Constant Speed Airscrew, bullet proof windscreen and domed hood. The A.&A.E.E. trials of N.3171 resulted in level speeds of 283 mph at sea level and 354 mph at 18,900 feet with the Merlin engine operating at 6.25 lbs/sq.in., 3000 rpm. For comparison, Spitfire Mk. I R.6774 equipped with de Haviland Constant Speed Airscrew and armoured windscreen achieved 288 mph at sea level and 355 mph at 17,800 using 6.25 lbs/sq.in., 3000 rpm. The similarly equipped Spitfire I R.6770, except fitted with 2 cannons and four Browning guns, reached 358 mph at 18,000 ft. 1e The Royal Aircraft Establishment (RAE) obtained 314 mph at sea level and 359 mph at a full throttle height of 11,500 feet using +12 lbs/sq.in. boost.

Also here: http://www.spitfireperformance.com/spitfire-I.html

Aeroplane and Armament Experimental Establishment Boscombe Down 30 July 1940
Comparison of Performance of Rotol and DH Airscrews on Spitfire

Both the aircraft are similar externally and are fitted with bullet proof windscreen and armour plating over the tank, etc.

Aircraft R6774 is fitted with DH airscrew and N3171 with Rotol airscrew.

It will be noted that these aircraft are about 12 miles an hour down in speed against the previously tested K9793, but the relative comparison remains. This loss in speed is accounted for, by 6 miles an hour for the bullet proof windscreen and 6 miles an hour due to loss in engine power.

So you can see that the TF4.5 Spitfire is modelled in error by taking the test results from the Battle of Britain specification N.3171, R.6774 & R.6770, then viewing the specification of non-Battle of Britain specification K.9787, K.9793 & L.1007, then making the calculation.

I don't know about the 109's other than they are, in all tests, considerably slower.

Sincerely hope that these issues can be fixed.

~S~