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Geronimo553

Why was the BF109K faster than the P51D? Video

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Found this lovely video that is very informative. So I thought I would share it for others to enjoy. Hopefully this will assist the devs as well.

 

Also Greg posts very informative quality videos in general, check out some of his other content.

 

Edited by Geronimo553
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I cant recall if he brings this up, but IIRC he does not. The 109 was not faster than the P-51D. At best altitude, both planes hit around the same 440mph. The Mustang was faster as altitude dropped off. 

 

The 454mph figure normally quoted is for a propeller than never entered production

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Great vid! If I was a mustang pilot I wouldn't be afraid of the K4 perhaps being marginally faster at certain altitudes. The K4's huge advantage in climb, acceleration and most likely sustained turn performance make it a very dangerous opponent.

Edited by JG27_PapaFly
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I highly recommend Greg's channel too. A lot of interesting stuff is explained as simple as possible. From a practical point there are water methanol kits for cars too. I wonder why the method  is not used by the cars industry. Not necessarily as a fighter perspective for boosting the power, but from the bomber perspective to increase the range.

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31 minutes ago, JG27_PapaFly said:

Great vid! If I was a mustang pilot I wouldn't be afraid of the K4 perhaps being marginally faster at certain altitudes. The K4's huge advantage in climb, acceleration and most likely sustained turn performance make it a very dangerous opponent.

If it weren't for it's climb rate the k4 would be easy to handle. It can climb away at will and can slow climb like mad.

Climb is what makes it most difficult for me to counter, speed/turn/acceleration aren't much of a problem for me, but for it to be able to climb so easily is a huge advantage for the K4.

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1 hour ago, Legioneod said:

If it weren't for it's climb rate the k4 would be easy to handle. It can climb away at will and can slow climb like mad.

Climb is what makes it most difficult for me to counter, speed/turn/acceleration aren't much of a problem for me, but for it to be able to climb so easily is a huge advantage for the K4.

 

Maybe the Lighting will be able to stay long enough in climbs to snipe the K4. Nose guns and counter-rotating props should help immensely.

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14 minutes ago, Ehret said:

 

Maybe the Lighting will be able to stay long enough in climbs to snipe the K4. Nose guns and counter-rotating props should help immensely.

 

109 pilot did say that one of the main tactics they used against the P-47 and P-51 (tight slow climbing turn) didnt work on the P-38 because it could stick right with the 109s due to it's low stall and good maneuverability.

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1 hour ago, JG27_Kornezov said:

I wonder why the method  is not used by the cars industry.

Because it's an inherently stupid thing to do, unless you are looking for bragging rights on the quarter mile. There are other means to get that kind of power today. But it exists. Occsionally. Methanol is not really cool for these purposes, as it enriches the mixture. It is less efficient than water in that respect. But Methanol helps faking a good "octane rating", as it ignites late. But the upside is, it doesn't freeze. Not really a problem for your racer car. But even the "water" in the Jug required some additives to keep it from freezing. But you know, you could run your engine on nitromethane. Like dragsters in the good old days. You can get a lot of power, but very little range.

 

1 hour ago, JG27_Kornezov said:

but from the bomber perspective to increase the range.

Water doesn't burn. It is heavyer than fuel. You get absolutely no range for the weight of the water and the and the whole system. If you are looking for range, adding displacement is adding less of a weight/space penalty then the injector kit and the water. Increasing fuel quality however (=/= octane rating) directly increases your range. The more efficient your burn, the more heat you get from it, the more range you get from it.

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Thanks for the link:

he BMW M4 GTS notices a 49 horse power gain from the water injection system over the competition pack M4.  BMW claims fuel efficiency can be increased by as much as 13 percent.  Emissions are lowered by as much as 4 percent.    These efficiency gains are typically seen with forced induction engines which output at least 107 hp per liter.  

The lower air temperature also prevents pre detonation of the air/fuel mixture.  Pre detonation has been a problem with turbo motors since turbos naturally heat the intake air.  The water injection system cools the air significantly enough to where the turbo's boost has been safely increased to 22 psi from the standard 17 psi on the base models.

What are the disadvantages?

The downside of this system is that you have another tank in your car to fill.  The BMW M4 GTS can seamlessly adjust for a full or empty reservoir without issues.  Bosch claims 1,800 miles can be driven on a full water tank before needing to be refilled.

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7 hours ago, JG27_Kornezov said:

The downside of this system is that you have another tank in your car to fill. 

...to fill with something that freezes in winter.

 

But it is a fun exercise indeed.

 

But power nowadays is really the least of your issues with engines. Also, emissions during leadfoot driving of these is something that diesn't translate into emisions measured by any standardized cycle. Hence, there is really nothing to be gained in terms of value for the car manufacturer. On the contrary. The injector system you had you have to charge in full on the extras list, making it really prohibitively expensive. You just don't earn money with that. Just to compare: Metallic paint is 500$ profit for 50$ cost. A sun roof is 2000$ loss over 4000$ you charge the buyer, but you absolutely have to feature a sun roof. But if you  make made that 7000$ for 1000$ profit, nobody buys the sun roof and your car will not sell.

 

It is not a product, unless somebody comes specifically asking for it for the simple reason that he wants it and he is willing to pay whatever it may cost.

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On 4/6/2019 at 7:21 PM, Legioneod said:

109 pilot did say that one of the main tactics they used against the P-47 and P-51 (tight slow climbing turn) didnt work on the P-38 because it could stick right with the 109s due to it's low stall and good maneuverability.

 

Good point! The P-38J will surprise a lot of Messerdweeb-pilots when it's releaseed.

 

The P-38 was very underrated among leading Luftwaffe pilots. Probably because they met the early versions in africa and only on very few occasions mixed with the late Js and Ls, which were transferred to 9th AF units by that time. I think the 479th transferred to P-51Ds in fall '44 and they didn't do too bad in the Lightning. Just ask Robin Olds, who made ace in three different types of aircraft. Not officially in the F-4, but there are people that seem to know a story or two about that episode of his career...

 

3 hours ago, ZachariasX said:

It is not a product, unless somebody comes specifically asking for it for the simple reason that he wants it and he is willing to pay whatever it may cost.

 

But that's ony a feature that's gonna fly with premium cars. You know, a six-wheel AMG G-Class Merc, etc.

"Real petrolheads" (TM) are looking for different solutions.

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45 minutes ago, Bremspropeller said:

 

Good point! The P-38J will surprise a lot of Messerdweeb-pilots when it's releaseed.

 

The P-38 was very underrated among leading Luftwaffe pilots. Probably because they met the early versions in africa and only on very few occasions mixed with the late Js and Ls, which were transferred to 9th AF units by that time. I think the 479th transferred to P-51Ds in fall '44 and they didn't do too bad in the Lightning. Just ask Robin Olds, who made ace in three different types of aircraft. Not officially in the F-4, but there are people that seem to know a story or two about that episode of his career...

 

 

But that's ony a feature that's gonna fly with premium cars. You know, a six-wheel AMG G-Class Merc, etc.

"Real petrolheads" (TM) are looking for different solutions.

 

Yep I think they'll be surprised by the Lighting.

One of the few German aces who gave credit to the P-38 is Johannes Steinhoff, he considered the toughest allied aircraft to fight when flown by a good pilot. He also said if a P-38 pilot spotted you during an attack there was little chance to get the kill since the 38 could maneuver so well.

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On 4/7/2019 at 2:00 AM, JG27_Kornezov said:

BMW M4 GTS notices a 49 horse power gain from the water injection system

The reason for that is the ability to run higher boost than without water-methanol injection. It significantly lowers intake air charge temperatures hence rising the detonation threshold that's why you can run higher boost without detonation. This is used quite often in tuned cars like Lancer Evos or STIs for example.

Edited by Arthur-A

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On 4/6/2019 at 7:21 PM, Legioneod said:

 

109 pilot did say that one of the main tactics they used against the P-47 and P-51 (tight slow climbing turn) didnt work on the P-38 because it could stick right with the 109s due to it's low stall and good maneuverability.

 

Only, the P-38 doesn't stall at particularly low speed. It has a 23% higher wing loading, assuming combat weights of 7000 and 3000 kg for the P-38 and 109, respectively.

For equivalent lift to be produced by its airfoil, it would've had to hit CLmax of around 2.8. However, the two airfoils used on the P-38 both have CLmax around 1.6 under lab conditions - that is to say, without interference from aerials, fuselage or engine nacelles.

 

In order to get close to the 109's wing loading, the P-38 would have to be run almost out of gas, considering its empty weight is over 5.8 tons, and engine power wise even the G-14 with its AM engine has around the same power/mass ratio (and probably better prop efficiency at most altitudes and speeds since the production P-38 was never refitted with a large chord paddle prop).

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11 hours ago, PainGod85 said:

 

Only, the P-38 doesn't stall at particularly low speed. It has a 23% higher wing loading, assuming combat weights of 7000 and 3000 kg for the P-38 and 109, respectively.

For equivalent lift to be produced by its airfoil, it would've had to hit CLmax of around 2.8. However, the two airfoils used on the P-38 both have CLmax around 1.6 under lab conditions - that is to say, without interference from aerials, fuselage or engine nacelles.

 

In order to get close to the 109's wing loading, the P-38 would have to be run almost out of gas, considering its empty weight is over 5.8 tons, and engine power wise even the G-14 with its AM engine has around the same power/mass ratio (and probably better prop efficiency at most altitudes and speeds since the production P-38 was never refitted with a large chord paddle prop).

P-38 has a power on stall speed of around 75-80 Mph IAS (gear and flap up), thats pretty good imo.

I'm also just relaying what the German Ace said the P-38 could do. All he said was the P-38 had no problem following them in a slow steep turning climb. He said it was a tactic he used constantly against P-51s and P-47s but that he couldn't use it against the P-38.

Edited by Legioneod

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21 minutes ago, Legioneod said:

P-38 has a power on stall speed of around 75-80 Mph IAS (gear and flap up), thats pretty good imo.

I'm also just relaying what the German Ace said the P-38 could do. All he said was the P-38 had no problem following them in a slow steep turning climb. He said it was a tactic he used constantly against P-51s and P-47s but that he couldn't use it against the P-38.

 

http://www.wwiiaircraftperformance.org/p-38/p-38-67869.html

 

Quote

 F.   Maneuverability

              The airplane is highly maneuverable considering the high wing loading. It has a fairly large radius of turn for a fighter but this is greatly improved by the use of maneuvering flaps.

 

V2NErTx.png?1

 

From NACA TN 1044: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930084610.pdf

 

You physically cannot have high wing loading and large turn radius while keeping a low stall speed, it's aerodynamically impossible.

 

So no, the P-38's CAS stall speed certainly isn't in even in the ballpark of 75 mph.

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8 minutes ago, PainGod85 said:

 

http://www.wwiiaircraftperformance.org/p-38/p-38-67869.html

 

 

V2NErTx.png?1

 

From NACA TN 1044: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930084610.pdf

 

You physically cannot have high wing loading and large turn radius while keeping a low stall speed, it's aerodynamically impossible.

 

So no, the P-38's CAS stall speed certainly isn't in even in the ballpark of 75 mph.

 

http://www.wwiiaircraftperformance.org/p-38/p-38-67869.html This is what I went off of. And also I'm telling you exactly what the pilot said, I don't see why you're trying to argue against it.

 

EDIT: Just realized we're using the same link/sources. It states a power on stall of 75mph with flaps and gear up. Also, P-38 doesn't have that large of a turn radius, it's better than the P-47 and P-51 iirc.

Edited by Legioneod

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Just now, Legioneod said:

http://www.wwiiaircraftperformance.org/p-38/p-38-67869.html This is what I went off of. And also I'm telling you exactly what the pilot said, I don't see why you're trying to argue against it.

 

Because your take on that report is demonstrably wrong. An airfoil tested to a CLmax of around 1.6 in the flight tunnel doesn't magically produce a CLmax of 2.8 once it's installed as a wing on a plane.

 

The P-38's manual value for indicated stall speed cites 95-100 mph. This is incompatible with the report's assertion that the plane stalls at 99 mph clean and power off, and it calls into question the speeds further cited for power on stall speeds at the very least.

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4 minutes ago, PainGod85 said:

The P-38's manual value for indicated stall speed cites 95-100 mph. This is incompatible with the report's assertion that the plane stalls at 99 mph clean and power off, and it calls into question the speeds further cited for power on stall speeds at the very least.

How are they in disagreement then? Seems that they agree with each other in indicated stall speeds.

Also, at the end of the day there's really no point in arguing over this, I was just stating what the Ace said himself, disagree with him all you want. I got no reason to argue.

Edited by Legioneod

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2 minutes ago, Legioneod said:

How are they in disagreement then? Seems that they agree with each other in indicated stall speeds.

Also, at the end of the day there's really no point in arguing over this, I was just stating what the Ace said himself, disagree with him all you want. I got no reason to argue.

 

Because the flight test data asserts the following:

 

Quote

Indicated airspeed
Corrected for instrument error

 

Emphasis mine. This means position error correction had ostensibly been performed. However, for all intents and purposes, the given stall speeds are what would be expected to be indicated, uncorrected readings because they compare well with what the pilot gets from his instruments - which, in every case back then, means uncorrected numbers.

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On 9/30/2018 at 7:28 AM, Lord_Flashheart said:

I cant recall if he brings this up, but IIRC he does not. The 109 was not faster than the P-51D. At best altitude, both planes hit around the same 440mph. The Mustang was faster as altitude dropped off. 

 

The 454mph figure normally quoted is for a propeller than never entered production

It's good that you pointed out the 452mph and propeller, gave me some insights but your statement that the K-4 wasn't faster than the P-51D isn't true at all. I analyzed some files and came across to the following speeds just for an example: 

 

6.000m alt: K-4 -> ~716km/h;  P-51 420mph (676km/h)

7.863m alt: K-4 ->~706km/h; P-51 -> 442-444mph (711-714km/h)

10.973m: K-4-> ~658km/h, P-51->404mph (650km/h)

 

So, overall except around 8-9km alt, the Bf109 K-4 is faster than the P-51D.

 

All the data was gathered by these official documents http://kurfurst.org/Performance_tests/109K_PBLeistungen/files/5026-18_DCSonder_MW_geschw.jpg and http://www.wwiiaircraftperformance.org/mustang/P-51D_15342_Level.jpg which I assume are the ones they used in game. For the K-4 I used the continuous thin line that corresponds to the propeller 9-12159, the one that entered in full production.

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Just now, 9./JG54_Yellow_13 said:

I think you forgot that 150 octane has a critical pressure altitude in the engine (full throttle height), in which after that doesn't make any difference in flight performance: http://www.wwiiaircraftperformance.org/mustang/tk589.html 

 

TK589 was not using 75" and had wing racks fitted.

75" Hg Mustangs were faster below full throttle height.

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28 minutes ago, Talon_ said:

 

TK589 was not using 75" and had wing racks fitted.

75" Hg Mustangs were faster below full throttle height.

Just stating, there's no way it could be faster than the K-4 at the altitudes stated, despite that at this graph, the 75"Hg boost has a full throttle height of around 10.500ft (3.200m) way lower than 6km as I prevously stated.

 

Considerantions: it's a P-51B, knowing being faster than the P-51D version, despite that, it's still slower than the K-4 at the highest speed. I'd love to see the extrapolations and files used in game to compare to the real result, as with 75" both planes are evenly matched up, with the tendency of P-51 having higher speeds at low altitudes (maybe high too with 75"?)

 http://www.wwiiaircraftperformance.org/mustang/p51b-speed-wf.jpg

p51b-speed-wf.jpg

Edited by 9./JG54_Yellow_13

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