190 A5 and A8

[Denniss]

And following that the G series.

No, that was a different beast. Long range fighter-bomber with additional DTs and reduced armament.

[GScholz]

It was a "mud mover" as Milo put it. With the success of the F series the Germans wanted a longer range version. They called it "Jabo Rei", short for "Jagdbomber mit vergrösserter Reichweite" (fighter-bomber with increased range).

[Krusty]

F-3 is corelates to the A-3, F-5 on the A-5, F-8 on the A-8, F-9 on the A-9, etc..

Would be nice if our F-8 got a little revamp (more ord/canon options/variety), and we got an earlier A-8 and turned the current A-8 into a much later A-8 (or leave it as is and add an A-9 ).

The "problem" with our A-8 is that it's been too averaged for a very wide-ranging and extremely dynamic plane varient (when looking at all of it's various possible production models and enmass field/powerplant upgrades).  Having two of it's heavier (and underpowered) varients as the ONLY available options in Aces High IS it's only "problem", at least imho.

You've got quite a few things mixed up there...

The F series is not analogous to the A series. the A-5 is where they really started creating F-3 models. A-5/U-kits were really the same as F-3 and G-3 variations. These designations were applied after the fact when it was decided an F and G line would be better off tailored to their specific duties.

The F-3 was directly built off of A-5s. They were identical. It was just a way of hanging an extra couple of bombs off the wings. It was not that different. When you get to the F-8 they renamed the system to match the equivelant A-series (so F8 = A8 with modifications). This is also when they started adding more armor specific to ground attack. Plates lined the belly of the plane, as well as the oil cooler ring being much thicker. No outboard guns were carried, ever, in F-models because weight problems. There would be a couple of bomb options to add to our F-8 but realistically speaking there's not much more to add to it. It didn't have any guns options.

The G-series was a bit different. These were intended to be long-range planes. They would replace the Ju87-R-2 series. They were meant to fly very long range sorties over relatively safe airspace and deliver a small bomb load and return to base. To this end they had plumbing on both wings to carry 2 DTs, and a centerline bomb. Rarely, you could have the opposite (single center DT and 2 wing bombs). They had the cowl guns removed, a reduced 20mm ammo load to save weight, and an added oil reservoir in the cowling to accomodate longer flight times. They had direction finding and sometimes autopilot equipment to better facilitate endurance flights. However, they were most often dropping a single bomb on one target at a time. Not very useful for AH.


Our 190A5 is actually modeled after a crashed/rebuilt G-3, reballasted to A-5 supposedly. HTC won't say this, but it matches the speed curves exactly. Other A-5s were much faster. Not sure if it was the captured/reworked nature of the plane, or what. We pretty much have the worst of the worst examples for our A-5 performance in-game. Not sure about how our A8 stacks up (normal, worse, better than average?).

EDIT: However, our A-8 has the weight of a sturmbock but NO armor benefit from one. It's significantly overweight by about 250kg, and the guns loadout weights seem a bit off-kilter too.

[Debrody]

The only place where the A-8's power curve is different from the A-5 is for WEP. That's because the A-8 has higher WEP boost which reduces full pressure height for each supercharger stage. More boost = more fuel burn = more air needed = lower altitude where the supercharger can deliver the needed pressure for full boost.

So the more boost it gets, the slower it is?
Seriously, that logic just cant be right. Reduce the boost and it will be faster at high alt? Then why the germans werent limiting the high alt boost on the A8? Just as how the G14 works, compared to the G6.

If a plane gets more power, its supposed to be faster, not slower, right?

[Charge]

According to my sources:

A4 -> F1
A5 -> F2
A5U17 -> F3
A7/A8 -> F8

As with F series there were only G1,G2,G3 and G8 used operationally.

***

According to my tests:

A5 has MIL 1.34ATA, WEP 1,42ATA, 19k FTH

A8 has MIL 1.34ATA, WEP 1.58/1.64ATA, 20k FTH

The speed curves do not look correct IMO. Increased boost should push the FTH downwards along the top line. See here: http://www.wwiiaircraftperformance.org/fw190/fw190-a8-12jan44.jpg

The FTH rises only with GM-1 where more oxygen is injected into engine via chemical reaction. MW50 and C3 only provide additional cooling and enable more ATA for engine. The curved top line for a supercharger is practically the speed limit of the charging impeller as it can only rotate at certain max speed after it starts to heat up radically and the efficiency starts to fall, this concerns the turbocharger as well.

***

No 190 had turbochargers, although Hirth turbos were tested along with inverted V engines. All German fighters were supercharged with various types and configuratins of superchargers. As a clarification a turbocharger utilizes exhaust pressure to charge incoming air, whereas supercharger takes its power mecanically from engine via a clutch, although 109s have a hydraulically coupled supercharger and that is why its speed curve is different to that of machanically coupled BMW801 of a 190.

-C+

[Denniss]

The 801s (and Jumo 211/213As) had a two speed supercharger, that's the break in the power curve, similar to the break in Merlin-powered engines when the second stage kicked-in.
DB engines had a single-speed supercharger with the noted fluid coupling.

F-1= A-4/U3
F-2= A-5/U3
F-3= A-5/U17, the first to be noted with underwing racks for 50kg bombs
F-8 -according to Fw docs they planned to remove some of the additional armor due to weight limitations

G-1= A-4/U8
G-2= A-5/U8
G-3= A-5/U13
G-8 - only built as pure groundattack G-8/R5, similar to the F-8 but without extra armor

[GScholz]

So the more boost it gets, the slower it is?
Seriously, that logic just cant be right. Reduce the boost and it will be faster at high alt? Then why the germans werent limiting the high alt boost on the A8? Just as how the G14 works, compared to the G6.

If a plane gets more power, its supposed to be faster, not slower, right?

Look, this is not rocket science ok; let's look at the speed chart for MIL power:



Both aircraft have the same engine power. You can clearly see how the A-8's heavier weight and more drag (gun bulges and protruding cannon muzzles etc.) causes the aircraft to be slower than the lighter and less draggy A-5. At the same engine power.

The only thing I find strange is the way both curves taper down to the same speed at sea level. I'd expect the A-5 to be faster at all altitudes.


Now let's look at the WEP speed chart:



Now the A-8 has more power than the A-5 and you can clearly see that the added power makes up for the added weight and drag. The A-8 is faster below 4k and between 10k to 18k. However the A-8's engine has the same supercharger so the added engine boost lowers full pressure height (the maximum altitude where the supercharger manages to provide full boost) to 18k from about 23k for the A-5. Above 18k the A-5 is faster not because it has more power, but because it is lighter and less draggy than the A-8. Above 23k both engines are again producing the same power since they are now limited by the supercharger.

[GScholz]

The speed curves do not look correct IMO. Increased boost should push the FTH downwards along the top line. See here: http://www.wwiiaircraftperformance.org/fw190/fw190-a8-12jan44.jpg

Well, if you look at the chart it actually does:



You can clearly see that the FPH of both supercharger stages are lowered for WEP.

MW50 and C3 only provide additional cooling and enable more ATA for engine. The curved top line for a supercharger is practically the speed limit of the charging impeller as it can only rotate at certain max speed after it starts to heat up radically and the efficiency starts to fall, this concerns the turbocharger as well.

Not quite; MW50 and C3 is injected in the eye of the supercharger, cooling the charge as it is compressed by the impellers. The cooling does not allow more pressure; it makes the charge denser. I.e. more air and fuel in the same volume at the same pressure. FPH is reduced since the supercharger must do more work to compress the denser air, but the benefit is greater than the loss:



As you can see, even above FPH there is a benefit of using MW50/C3 injection since the cooler, denser charge has more energy.

[Krusty]

I suspect the overweight nature of our A8 is the main culprit for speed... though I don't know why it would affect it THAT much. The outboard guns only detract 1 mph. The cowling bumps are minimal. Otherwise the airframe is identical, as far as drag, surface area, wing area, frontal area. Identical.

So I'm a bit at a loss as to why such a drastic difference off-wep. I've never really understood that part.

This is just for in-game curves. Historically the A-5 did even better than ours, so who knows what's going on.

[GScholz]

I'm guessing we have one of the Sturmbock versions with the heavy armor (including external armor on the sides of the cockpit) for bomber interception. Not the Normaljäger which was lighter and cleaner.

[Charge]

"The only thing I find strange is the way both curves taper down to the same speed at sea level. I'd expect the A-5 to be faster at all altitudes."

That tells me that between these two aircraft there is basically not much difference dragwise from aerodynamic point of view, not from guns or gun bulges. The difference starts to emerge with altitude because of increased weight which increases induced drag.

***

"You can clearly see that the FPH of both supercharger stages are lowered for WEP."

And that is correct, but the point is that you cannot go faster above FTH unless you get more air injected into engine and that happens only by installing a larger impeller which still has the same limitation for "tip speed" which affects the smaller impeller, so bigger impeller actually rotates slower in the axle than a smaller impeller but due to larger geometry it can move more air in less dense air, but still the "edge" of the impeller travels at the same speed as that of a smaller impeller. However, as you increase the impeller size its efficiency drops below that of a smaller impeller in denser air, possibly because its output needs to be heavily restricted to prevent over boosting because its rotation speed is tied to engine revs? This should not much of a problem in fluid coupled superchargers, as in DB605AS engines vs DB605. Interesting in this chart is that in 109 the airspeed is increased also above FTH: http://www.wwiiaircraftperformance.org/me109/me109g6-combat-emergency.jpg

Maybe the different behavior can be explained by the fluid coupling vs. clutched? But that would mean that in DB605 the impeller is not running at maximum speed which is possible due to fluid coupling. In FW that is not a option. There's two gears, low and high and the resulting impeller revs are tied to engine revs and the only way to limit boost is to regulate the air feed before (or after) the impeller.

***

So you can either rotate one impeller at various speeds, as it is done in 190, or you increase the number of impellers as in Spit 14 and Ta152 which is more efficient but comes with a noticeable weight penalty.
http://www.wwiiaircraftperformance.org/fw190/fw190-a8-3jan45.jpg

Or, you can provide additional oxygen chemically e.g. with GM-1. Which is what I think we see here: http://www.wwiiaircraftperformance.org/fw190/fw190-a8-level-speed-13nov43.jpg

***

"FPH is reduced since the supercharger must do more work to compress the denser air, but the benefit is greater than the loss"

That sounds logical too. I'm don't know which explanation is right.

I have tried to explain this rather difficult concept to myself by simply comparing the speed charts and the known charger configurations in various planes and I'm happy of any new information people can provide.  

-C+

[Krusty]

Oh, as a side note regarding F-1/F-2 models:

Technically it is true that the F-1 was based on the A-4 variant, however the main addition was a centerline ETC50 bomb rack and the deletion of outboard MG/FF weapons to save weight. Only 18 were built, since the A-4 was replaced by the A-5 quickly after the order was placed. The order was changed from 190A4/U3 to 190A5/U3, and the A5/U3 was intended to be the first F-1 production series. However, after-the-fact they named the small number of A-4/U3s as "F-1" and decided to rename the A5/U3s as "F-2." Only 60 of these were made. Also, our 190A-5 in-game has the ETC50 rack which was quite common, so we have that base covered. The main production variant was the F-3, which was essentially an A-5 with wing racks and possibly more protection for the fuel tanks. Over 270 of these were built ad well received by jabo units. It's main differing points from the F-8 is it did not have C3 injection, and did not have the aux tank to store extra fuel for this C3 injection. Main loadout was simply the 50kg racks outboard and 1 centerline DT or bomb.

For all intents and purposes, it really went from F3 to F8.

[Krusty]

Or, you can provide additional oxygen chemically e.g. with GM-1. Which is what I think we see here: http://www.wwiiaircraftperformance.org/fw190/fw190-a8-level-speed-13nov43.jpg

I'm not sure what those lines indicate, but it cannot be GM-1. GM-1 isn't allowed below 10,000 meters, and was never installed on any of those planes. It was a heavy installation and took up a lot of room. Looking at that chart it does seem that our A-8 matches the top SPEED of a standard A-8. We just have the weight performance problems. That means that once the weight is fixed our top speed might be adjusted back down a bit to stay in line.

[Wmaker]

I'm not sure what those lines indicate, but it cannot be GM-1. GM-1 isn't allowed below 10,000 meters, and was never installed on any of those planes.

Those lines look exactly what engaging GM-1 would look like as a performance gain similar curves are seen in plenty of other original speed performance docs which explicitly associate them as being due to the use of GM-1. The actual altitude at which GM-1 can be used depends on the feed rate of the nitrous oxide and the engine that it is being used in.

Here for example in this flight test of a Bf109G-3 (DB605A-1) GM-1 injection is engaged at 8000 meters:

1. Flug an 9.9.43

                      Steigflug mit Dauerleistung bis in VDH, über VDH
                      Steigflug mit Kampfleistung. Ab 8000 m Zusatzlich
                      GM 1.

http://kurfurst.org/Performance_tests/109G_Lmessung_gm1/109G3_16261_gm1.html#blatt1

While the use of GM-1 was very very rare, saying that it was never used by 190A isn't correct either. In his book Fw190 Jagdflugzeug Peter Rodeike for example mentions the use of GM-1 in an Fw190A-8/R4 in the end of '44/start of '45 by 10./JG 11. A GM-1 went into the same space that was normally occupied by the AUX tank.

[Debrody]

Both aircraft have the same engine power. You can clearly see how the A-8's heavier weight and more drag (gun bulges and protruding cannon muzzles etc.) causes the aircraft to be slower than the lighter and less draggy A-5. At the same engine power.
The only thing I find strange is the way both curves taper down to the same speed at sea level. I'd expect the A-5 to be faster at all altitudes.
Now let's look at the WEP speed chart:
(Image removed from quote.)
Now the A-8 has more power than the A-5 and you can clearly see that the added power makes up for the added weight and drag. The A-8 is faster below 4k and between 10k to 18k. However the A-8's engine has the same supercharger so the added engine boost lowers full pressure height (the maximum altitude where the supercharger manages to provide full boost) to 18k from about 23k for the A-5. Above 18k the A-5 is faster not because it has more power, but because it is lighter and less draggy than the A-8. Above 23k both engines are again producing the same power since they are now limited by the supercharger.

Thanks for explaining this for me.