general aircraft speed bug

[KEMPI]

Here is the H75 Wep vs No Wep.

[madrebel]

319 is faster than the fastest any P36 was ever tested at. Also, btw, critical altitude for the H75-A was higher than 1.5KM. Meaning the tested speeds of 311, 313, and those below are at much higher altitude.

http://www.wwiiaircraftperformance.org/P-36/Curtiss_Hawk_75-A_Detail_Specifications.pdf

note, that link has a two speed supercharger and is using the SC3-G variant of the 1830 making 1065HP.

and a test of the P36B showing a speed of 317.5 at 17K feet.

the P36 in game, if these tests are accurate, is significantly faster than any tested speed at 4500 feet, roughly a third of its critical altitude.

I'd be curious how fast the H75 is at 4.5KM.

Edited January 19, 2021 by madrebel

[Devildrivr]

23 hours ago, j10b said:

This is the scary thing.   Can someone disable or look at the trims?  its ridiculous that you have people mapping trim to game the game.  Most of the A/C in game didnt even have the option for trim. Now you have guys using trim like it snaps to 100% in an instant.  No its a wheel... usually in a not so user friendly location when you are in a fight.   Its faster and more abused than the automatic stick mounted trim on some of the advanced aircraft I've flown.   at this point with all the abuse it should be removed from game. 

I can't imagine what this is doing to player retention, especially when it comes to new members looking too subscribe and that are interested in the air combat aspect of the game. I think it would be hard enough with the steep learning curve as this game has a lot of moving parts and it can take time to fully retain and grasp.  I know there are a fair amount of good players that play and or that have played on and off for years, I too am one that has come and gone since the beginning and I do enjoy the dynamics of working as a team over discord to land a kill, with that said, diving in from 5km on an opponent is one thing, watching opponents complete high g maneuvers outside of what should be possible all while retaining energy to no end is another.  

[tcooper]

18 hours ago, Kempi said:

There is some user error in this also a few seconds from user error can skew the numbers.

Also @tcooper the mph is off I believe.

The only other way to measure this more accurately is to run it for 320km rather than 32km.

 

I am a little confused now. According to the german wikipedia, the mile used in aeronautics is scaled as 1 mile = 1.852 kilometers. So I used that. Is the stupid imperial system screwing with me and are the usual aircraft speeds quoted in landmiles as in 1 mile = 1.609 kilometers?

I always thought for aeronautics they use the same mile that is also used for knots, as seen here: https://www.metric-conversions.org/speed/kilometers-per-hour-to-knots.htm

Either way, thats just a problem of measurement units. My main argument of relative speed-advantages or disadvantages between the aircrafts in the game remains of course.

c00per

 

 

[slamen]

I just tested in Offline H75A

No wep

SL= 118.22 sec/square (16km)  ... 487kph or 302.7mph ..... things I noticed... MAP= 90

2.5km= 107.27sec/square....  537kph or 333mph      MAP= 88

4.65km= 99.6sec/square...    578kph or 359mph    MAP=80

5.79km= 99.53sec/square... 578kph or 360mph

 

 

 

[j10b]

20 hours ago, slamen said:

I just tested in Offline H75A

No wep

SL= 118.22 sec/square (16km)  ... 487kph or 302.7mph ..... things I noticed... MAP= 90

2.5km= 107.27sec/square....  537kph or 333mph      MAP= 88

4.65km= 99.6sec/square...    578kph or 359mph    MAP=80

5.79km= 99.53sec/square... 578kph or 360mph

 

 

 

thats not too bad its only 40 MPH faster than it should be. Which according to the tests by the allies the 109e Spitfire Mk I versus Me 109 E (spitfireperformance.com) is slower than the hawk in game.  Out run and out turn??? what more could you want??

[delems]

This is all really depressing.

Didn't think I could feel more pessimistic than during tier 0....  I was wrong.

[fidd]

The discrepancy may be TAS versus IAS. at 1,500m altitude, the difference between the two starts to become noticeable. TAS is used for navigational work, as with wind vector applied it give's ground-speed, but performance speeds are such as "top speed" are invariably quoted in IAS.

[rfh556]

I am looking for a little more clarification on what you are saying. The conversion from IAS to TAS should effect all aircraft roughly equally, I am not sure if each individual aircraft type has its own TAS model coded that would require a conversion into CAS or if it is just one universal IAS to TAS ratio for each aircraft but either way the difference between TAS and CAS is usually quite small.

All the aircrafts top speeds in difference altitude bands should be coded in either TAS or IAS but not a mix of the both. If they are a mix of both that in itself would be problematic.

[fidd]

6 hours ago, rfh556 said:

I am looking for a little more clarification on what you are saying. The conversion from IAS to TAS should effect all aircraft roughly equally, I am not sure if each individual aircraft type has its own TAS model coded that would require a conversion into CAS or if it is just one universal IAS to TAS ratio for each aircraft but either way the difference between TAS and CAS is usually quite small.

All the aircrafts top speeds in difference altitude bands should be coded in either TAS or IAS but not a mix of the both. If they are a mix of both that in itself would be problematic.

It is, as you say, negligable at the 2000' and speeds most Private pilots bimble around at, but as you get up towards 5000' it starts to become a factor for navigation. As you say, it will be an equal effect for all aircraft tested at the same altitude, however, if using the transit over points on the ground to compute speed, it's important to remember that it's that TAS value that you need to compute the IAS in which the top-speed is usually quoted, as it's the IAS which defines the performance of the aircraft. I forget the numbers these days, but the diifference quoted in expected and calculated speeds did appear to be "not inconsistant with", the differences between IAS and TAS at that altitude. The point is TAS is the basis for navigation, IAS the basis for the performance of the aircraft.

That is something of a simplification. I'd need to get  out my old text-books again to go through it all properly. Hope that helps.

I can't offer an opinion on the way our aircraft, and the atmosphere they flying, is modelled, as I have no idea how that was done.

Edited January 22, 2021 by fidd

[rfh556]

3 hours ago, fidd said:

It is, as you say, negligable at the 2000' and speeds most Private pilots bimble around at, but as you get up towards 5000' it starts to become a factor for navigation. As you say, it will be an equal effect for all aircraft tested at the same altitude, however, if using the transit over points on the ground to compute speed, it's important to remember that it's that TAS value that you need to compute the IAS in which the top-speed is usually quoted, as it's the IAS which defines the performance of the aircraft. I forget the numbers these days, but the diifference quoted in expected and calculated speeds did appear to be "not inconsistant with", the differences between IAS and TAS at that altitude. The point is TAS is the basis for navigation, IAS the basis for the performance of the aircraft.

That is something of a simplification. I'd need to get  out my old text-books again to go through it all properly. Hope that helps.

I can't offer an opinion on the way our aircraft, and the atmosphere they flying, is modelled, as I have no idea how that was done.

Ahh I see what you mean now. I was confused because I thought you were implying the fact that the speeds being TAS would effect how the aircraft ranked in regards to their order. They can't be used to compare to aircraft performance to their recorded specs but they can be used to compare relative aircraft as far as being able to see if they are in the correct order and roughly their relative performance (at 4921 feet the effects of IAS to TAS are still within %10 and it will effect performance numbers between relative aircraft by about a knot or two)

But too your point I did the TAS conversions, this is at 4921 feet assuming ICAO standard atmosphere as I don't know how the games atmosphere particularly temperatures vs altitude are coded (for clarification an increase or decrease of 15*C up or down will effect IAS 8 knots up or down for the fastest and 7 for the slowest aircraft). I am also assuming coopers numbers are in knots as they seem like they would be far too low all together if MPH 

A/C        KTAS      KIAS       MPH

F2          295          269         310

H75       291          265         305

E4         287          262         302

H81       286          260         299

E1         284          259         298

SIIb       283          258         297 

SIa        280         256          295

D520    261          238          274

DB7     259          237          273

110C   258           236          272

Hurri1   241        220            253

 

Even this though is kind of useless because aircraft manufactures are going to test their aircraft at their max performance altitude, which is going to be different for all of these aircraft. So these numbers are going to appear too high or low for any specific aircraft unless there max performance band is at 1500m(4921ft). Really you should get into the performance charts of the aircraft and look at what you should expect at that certain altitude. Either way the Hawk 75 seems way to fast haha.

I just ran the numbers again assuming a 2*C drop per '1000 and the speed numbers still seem relatively low for most aircraft across the board compared to the specs I am looking at, but again these numbers all come from a certain altitude band and the specs have all been from some different altitude.

Managed to track down some charts here.

http://www.spitfireperformance.com/

Interesting look at the ones where I can understand the language or at least understand some of the A/C types/engine names haha.

Edited January 22, 2021 by rfh556

[rfh556]

Speed testing for the P36, which ended up being in TAS anyways. Its a P-36A flown with a variety of propellers the fastest of which maxes out at as TAS of 281MPH or 244 TAS knots at '5000. Which at ICAO standard with 5*C works out to 227KIAS

http://www.wwiiaircraftperformance.org/P-36/P-36.html

Edited January 22, 2021 by rfh556

[fidd]

3 hours ago, rfh556 said:

Ahh I see what you mean now. I was confused because I thought you were implying the fact that the speeds being TAS would effect how the aircraft ranked in regards to their order. They can't be used to compare to aircraft performance to their recorded specs but they can be used to compare relative aircraft as far as being able to see if they are in the correct order and roughly their relative performance (at 4921 feet the effects of IAS to TAS are still within %10 and it will effect performance numbers between relative aircraft by about a knot or two)

But too your point I did the TAS conversions, this is at 4921 feet assuming ICAO standard atmosphere as I don't know how the games atmosphere particularly temperatures vs altitude are coded (for clarification an increase or decrease of 15*C up or down will effect IAS 8 knots up or down for the fastest and 7 for the slowest aircraft). I am also assuming coopers numbers are in knots as they seem like they would be far too low all together if MPH 

A/C        KTAS      KIAS       MPH

F2          295          269         310

H75       291          265         305

E4         287          262         302

H81       286          260         299

E1         284          259         298

SIIb       283          258         297 

SIa        280         256          295

D520    261          238          274

DB7     259          237          273

110C   258           236          272

Hurri1   241        220            253

 

Even this though is kind of useless because aircraft manufactures are going to test their aircraft at their max performance altitude, which is going to be different for all of these aircraft. So these numbers are going to appear too high or low for any specific aircraft unless there max performance band is at 1500m(4921ft). Really you should get into the performance charts of the aircraft and look at what you should expect at that certain altitude. Either way the Hawk 75 seems way to fast haha.

I just ran the numbers again assuming a 2*C drop per '1000 and the speed numbers still seem relatively low for most aircraft across the board compared to the specs I am looking at, but again these numbers all come from a certain altitude band and the specs have all been from some different altitude.

Managed to track down some charts here.

http://www.spitfireperformance.com/

Interesting look at the ones where I can understand the language or at least understand some of the A/C types/engine names haha.

That's all brought a lot back. As commercial instructor over 20 years ago, I used to be red-hot on all this hard-won theory. It's amazing how fast your brain dumps it when you've no longer got students with degrees in aeronautics seeking 'help' with ground-school when the weather clamped and we couldn't fly. It was often a toss-up as to whether they were teaching me - or vice versa. Hot on theory they may have been too, but it was the practical flying experience, good judgement and things like keeping a running mental plot of what was occurring unseen around you just from the RT, that they lacked. They learned damn quick though.

All you've typed above looks broadly correct in method. Personally I can't believe the figure for the H75. We are not talking about a particularly "slippery" airframe and so I'd not expect it, or the H81 to be especially quick, in fact, if asked to guess, I'd have put both at sub D520 speeds.

If it helps any of you to see the difference between TAS and IAS, In still-wind the TAS gives you your ground-speed. Your IAS gives you performance, meaning that flying at a particular IAS at 50' will feel exactly the same, in terms of response to control inputs, with the same rate-of-climb etc, as the same aircraft flown at the same IAS but at 10,000. You will need a lot more power just to achieve the same IAS at 10,000' as you would at 50'.

Edited January 22, 2021 by fidd

[fidd]

2 hours ago, rfh556 said:

Speed testing for the P36, which ended up being in TAS anyways. Its a P-36A flown with a variety of propellers the fastest of which maxes out at as TAS of 281MPH or 244 TAS knots at '5000. Which at ICAO standard with 5*C works out to 227KIAS

http://www.wwiiaircraftperformance.org/P-36/P-36.html

Do you mean that, or should the 2nd quoted "TAS" be IAS?

[rfh556]

9 hours ago, fidd said:

Do you mean that, or should the 2nd quoted "TAS" be IAS?

The documentation I posted shows "True Speed MPH" which I take as meaning TAS. The reports are from the War Department in 1940 though so maybe the nomenclature has changed and that isn't what they mean but that seems like a reasonable conclusion. 

Edit, ahh I see what you are getting at now, I just converted the 281 TAS MPH to 244 TAS Knots. I then converted the 244 KTAS to 227KIAS using ICAO standard atmosphere and a standard temperature lapse rate of 2*C/'1000 feet as I don't know the specific temperature that day, for reference a temperature +/-10*c of standard results in the a deviation of +/-4 KIAS.

Edited January 22, 2021 by rfh556

[j10b]

On 1/21/2021 at 1:58 AM, fidd said:

The discrepancy may be TAS versus IAS. at 1,500m altitude, the difference between the two starts to become noticeable. TAS is used for navigational work, as with wind vector applied it give's ground-speed, but performance speeds are such as "top speed" are invariably quoted in IAS.

Really, lets talk about TAS vs IAS which i used to calculate everyday in a Bomber.  This is NOT right in this case, as there is NO wind. 

[fidd]

13 minutes ago, j10b said:

Really, lets talk about TAS vs IAS which i used to calculate everyday in a Bomber.  This is NOT right in this case, as there is NO wind. 

I do not understand why you're talking about wind being a factor in IAS to TAS calculations. It's not relevant. The only relevance of wind in relation to TAS is in the calculation of ground-speed and drift angle, for computing time to fly between two physical locations and the heading and time required for the track flown to be between those two points.

[j10b]

On 1/22/2021 at 12:38 PM, rfh556 said:

The documentation I posted shows "True Speed MPH" which I take as meaning TAS. The reports are from the War Department in 1940 though so maybe the nomenclature has changed and that isn't what they mean but that seems like a reasonable conclusion. 

Edit, ahh I see what you are getting at now, I just converted the 281 TAS MPH to 244 TAS Knots. I then converted the 244 KTAS to 227KIAS using ICAO standard atmosphere and a standard temperature lapse rate of 2*C/'1000 feet as I don't know the specific temperature that day, for reference a temperature +/-10*c of standard results in the a deviation of +/-4 KIAS.

This is all good only if we have atmospherics.  You can use an E6b to get it in about 20 sec., or my super cool TAS/GS compass I have somewhere. Although for real life navigation purposes its best to use groundspeed, as you are navigating for timing ton a point. There are no environmental in this game so you are only solving for ground speed.  Generally speaking for military flight they use indicated.   

I am not sure where True comes into play here.  No fighter guy was spinning a whiz wheel, the bomber crews would, as they kinda had too.   I think the end of the day here, the H75 is faster than is should be.  Period Dot.  Because you have to assume the other side is using the lesser number, and that includes your own side.   Its hard to believe that they took the h75 up with a massive tailwind to get its true.  Which is now modeled in the game.   Physics doesnt work with the HP and type of engine it has with Hp to weight. 

[j10b]

17 minutes ago, fidd said:

I do not understand why you're talking about wind being a factor in IAS to TAS calculations. It's not relevant. The only relevance of wind in relation to TAS is in the calculation of ground-speed and drift angle, for computing time to fly between two physical locations and the heading and time required for the track flown to be between those two points.

OMG i love people with zero clue trying to come up with ways to justify.   So what relevance does TAS have here?    Oh you figured you would have a reason for the hawk to be faster.  Seeing no one else used TAS in their "top speed"  Just the hawk with less power...... Right.  Also neither IAS or TAS is irrelevant anyways as its not ground speed.   I read the true MPH not as TAS but as true ground speed corrected for wind.

Its saying for performance and in a perfect world this A/C will travel XXX MPH at this alt, SEL, ETC  

 

 

EDIT: also note the IAS decreases as we climb in the game...

 

a quote for those that have no clue about TAS. 

 

Indicated Airspeed, and True Airspeed are very close to each other.

But when you get hotter, colder, go faster or higher, the two differ from each other dramatically.

For example, at 25,000 feet the King Air I fly shows 180 knots indicated, but I file for 280 knots true airspeed on my flight plan. That’s a 100-knot difference between the two! The altitude and temperature are what drives the two apart.

Note, if I the airmass I flew through had no wind, my ground speed and true airspeed would be identical.

Edited January 25, 2021 by j10b

[fidd]

I fear you've completely misunderstood my posts. I have already posted that I find the in-game speeds of the H75 and H81, surprisingly high. I am NOT attempting to suggest that their current speeds are correct, or that either should, or should not, be faster than any other particular aircraft.. All I was trying to put across, is that TAS is not usually employed when charactering the speed of an aircraft (in comparison to others), but IAS is, and, that the apparent difference of two quoted top speeds for one of the aircraft that were being banded about looked to me, to be not inconsistent with one speed being quoted in IAS and the other in TAS, the latter being the faster of the two speeds.

All I was attempting to do was to ask those with access to the performance data in question, to verify that the quoted speeds were from charts in the same units, as mixed units would have resulted in something close to the apparent discrepancy.

In short, I was asking a question, not making a case.

Down Boy!

Also, if I were you, I'd not assume that others in here know less than you. There's a great many in here with expert knowledge in many different fields. Welcome to the game!

 

[rfh556]

2 hours ago, j10b said:

This is all good only if we have atmospherics.  You can use an E6b to get it in about 20 sec., or my super cool TAS/GS compass I have somewhere. Although for real life navigation purposes its best to use groundspeed, as you are navigating for timing ton a point. There are no environmental in this game so you are only solving for ground speed.  Generally speaking for military flight they use indicated.   

You are correct, we do not have wind components in the game but as far as we know the effects of altitude on IAS to TAS conversation are models, I am not sure if the effects of temperature are coded in or not. You don't need to get your E6B there are readily available means on the internet to do the conversion.

2 hours ago, j10b said:

I am not sure where True comes into play here.

TAS is being brought up because c00per ran speed tests on the aircraft by flying them between two know points on the map, in this case over two grid squares which is equal to 32 km. This would give us a TAS as since you stated there is no wind in game so groundspeed=TAS. I then converted all c00pers TAS numbers to IAS at 1500m's. The documentation I found of the Hawk 75 had its speed tests done in "True Miles Per Hour". Why they recorded that in True I don't know, you would have to take that up with some member of the War Department that did these tests in 1940.

2 hours ago, j10b said:

  No fighter guy was spinning a whiz wheel, the bomber crews would, as they kinda had too. 

No one is arguing that TAS is somehow relevant to a fighter pilot combat flying, it was being used because the numbers c00per recorded were in TAS, then converted.

2 hours ago, j10b said:

 

 I think the end of the day here, the H75 is faster than is should be.  Period Dot.  Because you have to assume the other side is using the lesser number, and that includes your own side.   Its hard to believe that they took the h75 up with a massive tailwind to get its true.

I assume you are now talking about the H75 documentation I posted.

TAS never includes wind, if they were recording the aircrafts speed on the ground by timing it over multi points then they would be recording groundspeed, if they wanted to find TAS from speed they would have to find the wind components from that flight and subtract that wind component to get an accurate measurement. More likely is they recorded the IAS and recorded pressure and temperature on that day then converted it to TAS in hopes that it would make numbers recorded on different days and different conditions more comparable (Yes I know temperature and pressure will have other effects on the A/C other then effect IAS to TAS conversions.)

I highly doubt the War Department when testing different types of propellers and deciding which one would be best suited for the A/C would be intentionally recording Groundspeeds and trying to pass them off as True Airspeeds.

2 hours ago, j10b said:

 

  Which is now modeled in the game.   Physics doesnt work with the HP and type of engine it has with Hp to weight. 

 

[fidd]

On 1/19/2021 at 8:08 PM, tcooper said:

 

I am a little confused now. According to the german wikipedia, the mile used in aeronautics is scaled as 1 mile = 1.852 kilometers. So I used that. Is the stupid imperial system screwing with me and are the usual aircraft speeds quoted in landmiles as in 1 mile = 1.609 kilometers?

I always thought for aeronautics they use the same mile that is also used for knots, as seen here: https://www.metric-conversions.org/speed/kilometers-per-hour-to-knots.htm

Either way, thats just a problem of measurement units. My main argument of relative speed-advantages or disadvantages between the aircrafts in the game remains of course.

c00per

 

 

Speeds for aircraft are almost universally quoted in knots, ie nm/hr. You're correct in saying that 1nm = 1.852km. The knot is used because it is much more useful for dead-reckoning navigation methods than any metric value. 1 degree subtending to a distance of 1mn at 60nm range. From this, if you're 5 miles off track at 30 miles distance since your last fix, then that'd mean an error of 10 miles at 60 nm range, giving a 10 degree drift angle, therefore you need to adjust your heading twice that, ie by 20 degrees to arrive back on track after a further 30 miles. It's the sort of useful mental-arithmatic you can easily do in your head if you havn't a navigator or a suite of nav instruments to use. It's not super precise, but it's "close enough for government work". If pilots used kmh then the arithmatic for a lot of these speed/distance/time/drift/heading calculations become a lot harder, because you lose the relationship between distance and degree that exists with degrees and nautical miles or knots.

I tend to work in metric, but it's worth remembering that a lot of Imperial measurement conventions were based in real life, and directly applicable, distances, such as the turning-circle of a team of horse pulling a plough for example. Which is why the system lasted well into the 20th Century in the English speaking world. Metric is good, but it Imperial is better in some circumstances - aviation being one. It's also harder to make a balls-up of fuelling an aircraft in Imperial - no decimal points to get wrong, so metric does have some draw-backs.

[rfh556]

On 1/21/2021 at 10:37 PM, rfh556 said:

Ahh I see what you mean now. I was confused because I thought you were implying the fact that the speeds being TAS would effect how the aircraft ranked in regards to their order. They can't be used to compare to aircraft performance to their recorded specs but they can be used to compare relative aircraft as far as being able to see if they are in the correct order and roughly their relative performance (at 4921 feet the effects of IAS to TAS are still within %10 and it will effect performance numbers between relative aircraft by about a knot or two)

But too your point I did the TAS conversions, this is at 4921 feet assuming ICAO standard atmosphere as I don't know how the games atmosphere particularly temperatures vs altitude are coded (for clarification an increase or decrease of 15*C up or down will effect IAS 8 knots up or down for the fastest and 7 for the slowest aircraft). I am also assuming coopers numbers are in knots as they seem like they would be far too low all together if MPH 

A/C        KTAS      KIAS       MPH

F2          295          269         310

H75       291          265         305

E4         287          262         302

H81       286          260         299

E1         284          259         298

SIIb       283          258         297 

SIa        280         256          295

D520    261          238          274

DB7     259          237          273

110C   258           236          272

Hurri1   241        220            253

 

Even this though is kind of useless because aircraft manufactures are going to test their aircraft at their max performance altitude, which is going to be different for all of these aircraft. So these numbers are going to appear too high or low for any specific aircraft unless there max performance band is at 1500m(4921ft). Really you should get into the performance charts of the aircraft and look at what you should expect at that certain altitude. Either way the Hawk 75 seems way to fast haha.

I just ran the numbers again assuming a 2*C drop per '1000 and the speed numbers still seem relatively low for most aircraft across the board compared to the specs I am looking at, but again these numbers all come from a certain altitude band and the specs have all been from some different altitude.

Managed to track down some charts here.

http://www.spitfireperformance.com/

Interesting look at the ones where I can understand the language or at least understand some of the A/C types/engine names haha.

 

Managed to track down a 109F2/F4 Performance table. The report looks like it was done by a US company during WWII.

Edit. Actually I just realized that the 310 MPH I posted above is MPH Indicated. So then this charting is showing very different speeds. As 310 MPH true would be about 270 KTAS.

That makes me wonder if there if there was an error in data reading when the speeds were programmed into the game. Though probably not, its most likely just a coincidence that they line up.

Plus I found an original German source that is showing different numbers anyways so the estimates from that US report just might not be that good.

Edited January 26, 2021 by rfh556

[rfh556]

Also here is the link to the thread where I found the performance data. Lots of cool old reports on that forum in general.

https://ww2aircraft.net/forum/threads/bf-109-performance-thread.16470/

[fidd]

10 hours ago, rfh556 said:

 

Managed to track down a 109F2/F4 Performance table. The report looks like it was done by a US company during WWII.

Edit. Actually I just realized that the 310 MPH I posted above is MPH Indicated. So then this charting is showing very different speeds. As 310 MPH true would be about 270 KTAS.

That makes me wonder if there if there was an error in data reading when the speeds were programmed into the game. Though probably not, its most likely just a coincidence that they line up.

Plus I found an original German source that is showing different numbers anyways so the estimates from that US report just might not be that good.

Bear in mind that the German's had very limited access to tetra-ethyl lead after 1941, and therefore no 100 Octane, so I'd expect their performance figures for trials of captured aircraft to be slightly poorer in relation to allied figures.