109 e3b against spitfire II

[Blackdog_kt]

Originally Posted by Seadog

Asking for more power is exactly the same as asking for higher octane fuel. ( I didn't have to wait long for the "we don't need no stinking 100 octane fuel" claims from the Lufters... )

No it's not. An engine of a sufficiently bigger displacement running "normal" fuel with the appropriate boost values will still outperform an engine with a lower displacement. If they have similar displacement a smaller engine running 100 octane could reach or even surpass the HP of a bigger one running 87 octane, but a sufficiently bigger displacement would ensure superior performance even when running fuel of a lesser octane rating.

And that's without even taking into account other things like supercharger design and gearing and propeller design, things which affect not only the powerband of the engine but also the appropriate altitudes where the extra power can be better used.

What i'm trying to say is that asking for engines with more HP can mean a combination of many different things. When you are discounting them all and pretend its only the octane rating that matters you are just simplifying for the sake of pushing a personal viewpoint without having to come up with the supporting proof: "they asked for more power, so they should surely mean a better octane rating".

I'm all for Spits and Hurricanes getting their 100 octane and constant speed prop variants. Keep the current ones for battle of France scenarios (i mean we already have much of the map so why lose the ability to create such missions) and let's also add the proper battle of Britain variants.

I'm also in favor of having a 50% chance (or whatever the appropriate percentage was) of spawning with DB601N engines on your 110, which you make absolutely no mention off in any of your arguments. I've given you the benefit of doubt until now but you're gradually exhausting that reserve.

No offence meant and i'm not saying you're just pushing for a gameplay advantage for your favorite ride because i'm not the kind of fool that will pretend to know what's in another person's mind. What i'm saying is that you sure sound like that more and more as time goes by, i just don't have a way to confirm it, which makes me averse to getting convinced out of a matter of principle. I guess this goes for many others as well.

[Seadog]

Originally Posted by Blackdog_kt

1)What i'm trying to say is that asking for engines with more HP can mean a combination of many different things. When you are discounting them all and pretend its only the octane rating that matters you are just simplifying for the sake of pushing a personal viewpoint without having to come up with the supporting proof: "they asked for more power, so they should surely mean a better octane rating".

I'm all for Spits and Hurricanes getting their 100 octane and constant speed prop variants. Keep the current ones for battle of France scenarios (i mean we already have much of the map so why lose the ability to create such missions) and let's also add the proper battle of Britain variants.

2)I'm also in favor of having a 50% chance (or whatever the appropriate percentage was) of spawning with DB601N engines on your 110, which you make absolutely no mention off in any of your arguments. I've given you the benefit of doubt until now but you're gradually exhausting that reserve.

3)No offence meant and i'm not saying you're just pushing for a gameplay advantage for your favorite ride because i'm not the kind of fool that will pretend to know what's in another person's mind. What i'm saying is that you sure sound like that more and more as time goes by, i just don't have a way to confirm it, which makes me averse to getting convinced out of a matter of principle. I guess this goes for many others as well.

1) Again, pilots wanted more power. In the Merlin III, 30% more power was available through a simple mod, that could be done in an afternoon using fuel that was readily available. RAF pilots had been aware of this for several years, and they got a full transition to 100 octane prior to the BofB, indeed many France based Hurricane squadrons used it during the BofF. I don't and haven't discounted other options, but raising displacement, for example, invariably means greater weight and greater frontal area, something that pilots don't want.

2) see my post #71:
http://forum.1cpublishing.eu/showpos...1&postcount=71
By all means, include all historical engine and aircraft variants.

3) No, I am pushing for a game that sims RL. In RL Merlin III aircraft have access to much higher power at low altitude. At high altitude these advantages dwindle and the Me109 has many advantages, and this will force the Me109 pilots to fly as per RL, IE, stay high, and fight in the vertical. Dogfighting Hurricanes at low altitude is not a great idea. The RAFFC made a rapid transition to 100 octane engines and CS props and it was a much tougher proposition than the Luftwaffe had been led to believe, but thats how it was.

[Kurfürst]

Originally Posted by Seadog

I don't and haven't discounted other options, but raising displacement, for example, invariably means greater weight and greater frontal area, something that pilots don't want.

Compared to that theory, German DB 601 was same size as weight as single stage Merlin, 605 actually lighter then two staged Merlin, while the French 35-liter class Hispano Suize V12s were considerably lighter than both.

The only practical way a smaller displacement engine can keep up with larger ones is by heavy supercharging, but that does not comes free, superchargers and their systems add weight, and so does decreasing fuel effiency: more fuel need to be carried for same range.

[Seadog]

Originally Posted by Kurfürst

Compared to that theory, German DB 601 was same size as weight as single stage Merlin, 605 actually lighter then two staged Merlin, while the French 35-liter class Hispano Suize V12s were considerably lighter than both.

The only practical way a smaller displacement engine can keep up with larger ones is by heavy supercharging, but that does not comes free, superchargers and their systems add weight, and so does decreasing fuel effiency: more fuel need to be carried for same range.

They are similar, but the Merlin is a bit lighter:


from Flight, April 16 1942.
The net dry weight of the DB601N is stated in the article to be 1400lbs, but OTOH, Merlin engines were being run at much higher boost pressures when this article was written and thus greater power.

A Merlin III/XII/45 net dry weight = 1375/1420/1385lb

The article states that the DB601N had greater frontal area:
http://www.flightglobal.com/pdfarchi...0-%200807.html
and an article on the Merlin XX:
http://www.flightglobal.com/pdfarchi...0-%200449.html

[Crumpp]

Check the math on that document....

1430lbs / 1175hp = 1.21 lb/hp not 1.13lb/hp....

The Merlin has the same power to weight at the DB601.

[Seadog]

Originally Posted by Crumpp

Check the math on that document....

1430lbs / 1175hp = 1.21 lb/hp not 1.13lb/hp....

The Merlin has the same power to weight at the DB601.

It actually states 1450 lbs but also 1240hp at 2850rpm @ 10,000ft (two values given for the Merlin XX)

However, the DB601N power is WEP. The equivalent figure for a Merlin XX would be 1485hp at 14lb/3000rpm @ 6000ft and 1490hp at 16lb/3000rpm @ 12500 ft and 1280hp at 3000rpm/12lb @ TO, at least in 1942 but the TO figure is applicable to 1940 as well.

[robtek]

you actually implement that in a comparision wep is set against full mil.????
You are talking about the N, not the A.

[Viper2000]

Originally Posted by Kurfürst

Compared to that theory, German DB 601 was same size as weight as single stage Merlin, 605 actually lighter then two staged Merlin, while the French 35-liter class Hispano Suize V12s were considerably lighter than both.

The only practical way a smaller displacement engine can keep up with larger ones is by heavy supercharging, but that does not comes free, superchargers and their systems add weight, and so does decreasing fuel effiency: more fuel need to be carried for same range.

Actually, if you do the thermodynamic analysis, you'll tend to find that supercharging doesn't particularly damage fuel efficiency, provided that you have reasonable component efficiencies and make a fair comparison (which is the difficult bit).

Power:weight at sea level will tend to be fairly insensitive to supercharge because the supercharged engine sees higher pressures and therefore has to be heavier, whilst OTOH the unsupercharged engine is bigger. So you end up with a small area of thick metal vs a large area of thick metal.

The supercharged engine has a higher power density, and this will tend to make life harder for the cooling system.

If you compare at fixed cruising speed, there will be an optimum degree of supercharge, beyond which you'll lose more from the increased cooling problems than you've gained from the smaller engine. OTOH, because the supercharged engine is smaller, it has less non-cooling drag, and so you'd expect to cruise faster, which helps to make the radiator smaller.

In the end, the trade space is complex, and it isn't especially easy to make a general case that one approach to engine design is better than another. Hence the diversity of engine designs; if there was a trivial optimum then engine designers would have swiftly converged upon it, and the world would be a much less interesting place.

[TomcatViP]

Originally Posted by Viper2000

OTOH, because the supercharged engine is smaller, it has less non-cooling drag, and so you'd expect to cruise faster, which helps to make the radiator smaller.

Funny that Merlin Vs DB tell the opposite.

Seems you forgot one parameter : rpm and charging raise the strain and the temp with negative consequence on efficiency: try to win the 24h Le Mans race with a 2L engine and then jump in 7.0L 'vette

To put it in perspective : there was no successful post war Merlin engined airliner. But lot of with P&W primitives big radials

[Viper2000]

Originally Posted by TomcatViP

Funny that Merlin Vs DB tell the opposite.

Seems you forgot one parameter : rpm and charging raise the strain and the temp with negative consequence on efficiency: try to win the 24h Le Mans race with a 2L engine and then jump in 7.0L 'vette

To put it in perspective : there was no successful post war Merlin engined airliner. But lot of with P&W primitives radials

rpm isn't especially interesting. Piston speed is generally a better metric.

Liquid cooled engines run colder than air cooled engines, and actually one of the main problems for the Merlin was over-cooling of the charge during cruising flight, which necessitated modification of the aftercooler to act as a heater to prevent the charge temperature falling below 40ºC.

The Merlin powered version of the DC-4, the Canadair Northstar was considerably faster than its radial engined equivalent. Noise was a problem initially due to the stub exhausts; the big radials tended to have collector rings; a crossover exhaust for the Merlin mitigated this to some extent. It wasn't an unsuccessful machine, but it wasn't ever going to capture the US market because it wasn't American.

As for perspective, how many DB powered airliners were there post WWII?

The Merlin wasn't successful as an airliner engine for many reasons - it hadn't be designed for that sort of duty for a start. It did rather better than the V-1710 though.

But perhaps the main reason for its "failure" as an airliner was that there just weren't suitable British airliners to bolt it onto. Lancastrian, York & Tudor could hardly compete with contemporary products from Lockheed & Douglas, because Britain had basically stopped airliner development in 1939 whilst the Americans had continued throughout the War (because they needed long-range transports anyway). They weren't about to put British engines onto their aeroplanes if they could possibly help it, so the considerable technical lead of the American airframers translated directly into market share for their engine manufacturers.

It's probably better to compare the Merlin's civil record with that of Hercules & Centaurus, which faced a similar airframe problem (though of course at this time Bristol had an aeroplane division as well, which provided them with a captive market for their engines).

In this context, the Merlin doesn't look so bad.