Author Topic: SpitI and 109E4 (Read 519 times)

niklas · « **on:** March 16, 2002, 07:55:30 AM »

After the correction of the Emil i had a look at the charts, and i´m wondering myself a bit now.

First what i know about the Spit1a:
The Merlin III engine (it is a Merlin III isn´t it?) had basically the same performance like a Merlin II, but a Rotol or De Havilland variable pitch airscrew could be mounted. Btw, Is it true that the Merlin III did not have a pressurized water cooling system -introduced with Merlin IV- and still used Aethylenglycol? If so, than i understand now why the 109 was considered better especially in high altitudes.

Anyway, the performance of the Merlin II/III:
Maximum Takeoff 3000rpm, 6 1/4lb, 0ft: 880hp
Maximum Rated altitude 3000rpm, 6 1/4lb, 16k: 1030hp
with 2850RPM, 6 1/4lb, 15k: 1025hp

In AH 6 1/4lb is normal power, and you can boost the engine to 71/2, almost 8. Isn´t this too much power then?

On the other hand, even with normal power, the spit can´t reach the 16k critical altitude. Performance begins to drop at 10k. There seems to be also a bug with the boost indicator of the Spit I: At 10k it begins to drop, but at ~14k it begins to raise again to the maximum, like a 2nd stage (Though performance doesn´t raise).

Now the Emil had the DB601A. Instead "more boost", it looks like we don´t have the takeoff boost at all(1,4 ata, 2400rpm). Instead it looks like we have the 5min rating (1,3ata, 2400rpm) for emergency power.
Ok, takeoff power was only allowed in very low altitudes, but a little more performance for short sprints or climbs in low dogfights is very helpful.
Next little problem: The critical altitude seems to be only 4km, but this was the old charger of the 601A0 or B0 series. The A1 and B1 mass production engines had the 4,5km charger.

Now my real question: how does it come that Spit1 can climb with Emil? The SpitI was 400lb heavier, and has near ground 100hp less power, even without the takeoff power of the Emil. I can´t see any reason why the spit should climb as well as a Emil (I don´t consider 50ft/min a difference).

niklas

mora · « **Reply #1 on:** March 16, 2002, 10:48:20 AM »

I have always thought that 109E had a slight edge over Spit I in climb and speed, but according to HTC charts there is virtually no difference.

Of course I could be wrong.

SageFIN · « **Reply #2 on:** March 16, 2002, 11:05:42 AM »

Well, for climb, thrust vs. weight. Weight... ok, so the Spit is heavier. Thrust -- Spit has less HP, but apparently has more thrust. Does it have a better propeller? Exhaust thrust? (didn't AH use a generic efficiency value for all props though?) Also, the Spit has cleaner airframe and less drag, but I'm sure that the effect is negligible at climb speeds (correct me if i'm wrong).

Sox62 · « **Reply #3 on:** March 16, 2002, 01:28:56 PM »

Don't forget wingloading.

niklas · « **Reply #4 on:** March 16, 2002, 03:07:24 PM »

I slowly get the impression that the topspeed of a Merlin III engine was combined somehow with a climb performance of a Merlin VII from a Spit MKII.

The climb performance peaks out in 10k, the topspeed in 16-18k. Too much difference for a ram-effect imo. It can be explained
a) by a lot less rpm for climb, especially in combination with a 2 pitch propeller, but this isn´t the case here
b) more boost. But more boost for the climb? The spitfire performance test shows a test with rotol propeller which comes close to the AH performance, but the rotol propeller wasn´t realized until the MKII and furthermore i´m convinced that a VII engine or RM2M engine was installed in this test that produced more power.

Sox, lower wingloading gives you an advantage in high altitudes. In low-mid altitudes, the lower weight and less drag of a design with higher wingloading (smaller wing) is better for a climb.

niklas

Wilbus · « **Reply #5 on:** March 17, 2002, 06:37:20 AM »

Spitfire Mk I used a Merlin II Niklas, will dig up some more numbers and post about the 109 E3/4 and Spitfire Mk1 tonight.

Nashwan · « **Reply #6 on:** March 17, 2002, 11:36:36 AM »

Only the first 74 Spit I's used a Merlin II, the rest had the Merlin III.

Seeker · « **Reply #7 on:** March 17, 2002, 11:54:16 AM »

Has any one noticed the trimming in these two A/C?

I know combat trim is only supposed to be aproximate; nontheless, I do find it surprising that CT is *much* closer to optimum on the 109 than the Spit.

Every source I've ever read, and I mean *every* source, says a 109 at high speed needs constant left rudder. Ours don't. This should be especily marked in the early 109's.

I do wish that this a-historical crutch could be removed.

No trim, nor ammo counters for planes that did not have them, thank you very much.

What's next, sidewinders?

Wilbus · « **Reply #8 on:** March 17, 2002, 12:07:48 PM »

Cc Seeker, aswell as other things, specially 190's, needed no trimming. Sidewinders and amrams coming soon...

Seeker · « **Reply #9 on:** March 17, 2002, 12:23:58 PM »

"specially 190's, needed no trimming"

If that's true, how come a leading cause of 190 crashes was pilots playing with that electric trim thingy (which I will make no attempt to pronounce nor spell), trying to tighten the turn with tail up trim?

Over do it, and it would snap roll violently and auger.......

All planes need trim, all the time (well, post WWI, any way). The point is, was it set on the ground for an optimum speed (109 rudder trim); or could the pilot set it himself (most later planes).

The 109 should be out of trim at anything less than it's optimum (at least, any thing earlier than the G models, I beleive) - it's one of it's most known charecteristics, just like the early merlins cutting under negative G.

J_A_B · « **Reply #10 on:** March 17, 2002, 12:57:30 PM »

The problem is trim in a real aircraft doesn't work like trim in a simulation because our desktop joysticks don't work the same. As a result the effects of trim in a game are considerably more pronounced than in the real world. This is why all airplanes have in-cockpit adjustable trim for all axis, although their real-world counterparts often did not.

I seriously question the value of bothering to model trim in a game; it simply doesn't work right. At the same time not having it at all isn't a very good solution. There just doesn't seem to be a good answer.

J_A_B

Wilbus · « **Reply #11 on:** March 17, 2002, 01:57:49 PM »

Seeker, the 190 Elevator was the only thing that could be trimmed in the air. Rudder and ailerons needed no trimming becaus they staied the same (very close, only very small changes) in all speeds. The elevator could be trimmed 2 degrees up and 1.5 degree down, far less then any other plane during the war, it was not required to trim more because the elevator too, staied almost the same in all speeds.

The 190 design team with Kurt Tank in the lead, put in a great deal of time in balancing the controls like this and they succeeded. Like you said, it was trimmed with electrical buttons (first all electrical fighter in the world) but not more then +2 and -1.5 degrees.

The reason pilots "play" with the trim to tighten then turn is so they don't have to have the stick pulled back all the time, of course there was a difference between 450mph and 170 in a turnfight but FAR from as much as in other fighters at the time.

This is something that is not modelled in AH and it takes away one of the 190's many superior things and advantages over other planes through out the war.

A good source is "Focke Wulf Fw190 in Combat" by "Alfred Price".

Seeker · « **Reply #12 on:** March 17, 2002, 02:12:03 PM »

"The 190 design team with Kurt Tank in the lead, put in a great deal of time in balancing the controls like this and they succeeded. Like you said, it was trimmed with electrical buttons (first all electrical fighter in the world) but not more then +2 and -1.5 degrees. "

Granted, it was revolutionary, and very, very good. But not perfect.

"The reason pilots "play" with the trim to tighten then turn is so they don't have to have the stick pulled back all the time, of course there was a difference between 450mph and 170 in a turnfight but FAR from as much as in other fighters at the time."

You're commenting on the use of trim in normal flight. My point with respect to the Wulf was that pilots over used it, especialy green pilots, and it killed them.

However, that wasn't the thrust of my post. I only ever see comments on negative aspects of LW rides - I've never seen a post saying something along the lines of "Please remove trim on the 109, it's historicaly incorrect. And while you're at it, please fix the Spit's roll, that seems a bit off too".

Posts saying in effect "It's LW, so it'll not only be made porked, but will remain so" are counter productive to all concerned. It's a fact that very often, the LW fans are indeed the most informed and the most passionate about thier rides; which can lead to differences of opinion and frustration.

It's a myth to think they're the only ones, or a special case, either positively or negatively.

Single issue politics are allways suspicious.

Wilbus · « **Reply #13 on:** March 17, 2002, 03:02:25 PM »

Agreed seeker, it was definatly not perfect, however in terms of Trimming, the 190 was near perfect

Like I said, ailerons and rudders needed no trimming at all, elevator needed some in big speed changes and to have alot of trim up made it easier to fine adjust in turns. However, you don't turn better when you trim then if you have stick fully back, hard to explain, don't get a better turn radius thanks to trim, just takes some preasure off the stick.

Allso, 109 trims that didn't exist (aileron and rudder) should be removed as well as ammo counters on planes that didn't have them.

Kweassa · « **Reply #14 on:** March 17, 2002, 05:34:53 PM »

Quote

Also, 109 trims that didn't exist (aileron and rudder) should be removed as well as ammo counters on planes that didn't have them.

Agreed.

Take the fantasy trims out, and take the ammo counters out in other planes. I think that's actually more profit for LW planes than other people can bear