109 elevator trim

[Al Schlageter]

http://www.wwiiaircraftperformance.o...ricane-109.pdf

see 5.

Note the comment by the pilot of the 109 saying the trim adjustment was heavy. In other words, it was not easy to rotate the wheel.

No wonder the 190 went to an electrical trim for the stab.

[irR4tiOn4L]

Originally Posted by Al Schlageter

http://www.wwiiaircraftperformance.o...ricane-109.pdf

see 5.

Note the comment by the pilot of the 109 saying the trim adjustment was heavy. In other words, it was not easy to rotate the wheel.

No wonder the 190 went to an electrical trim for the stab.

That was in a dive, where the 109's controls were all very heavy! That is not representative of how heavy the trim might be in a horizontal maneuver. Additionally, others have said the large wheel made it easier than competing designs, and I don't think we should be looking at the 109 trim in isolation.

What SHOULD be taken into accound in CLOD, and is not, however, is the reputed heaviness of the 109's controls in a dive. I've never had to use trim to pull out of a high speed dive in CLOD, and I feel that I should.

What is also interesting out of your linked notes is that the 109 lacked oxygen gear - would this result in a higher effective ceiling for the red fighters?

Extremely interesting also is the pilot's notes on the tendency of the Hurricane pilot to black out where the 109 pilot would not. Initially I read this as pulling more G's, but in actuality, they are saying that the pilots of a hurricane sat more vertically and had a tendency to black out even in similar g maneuvers! I definitely don't see blackout tendencies modelled in the sim, and that would make it rather interesting, wouldn't it, if the 109's pilots could sustain more g without blacking out!

We shouldn't pay attention to just one aspect of that pilot's report.

[Igo kyu]

Originally Posted by irR4tiOn4L

What is also interesting out of your linked notes is that the 109 lacked oxygen gear - would this result in a higher effective ceiling for the red fighters?

No.

What is said is that the RAF lacked oxygen bottles with connectors compatible with Luftwaffe oxygen systems.

Without oxygen, 18,000 ft is a hard ceiling for pilots, and even 17,000 is iffy.

IIRC it turned out that the 109 was much better than the Spitfire at very high altitudes, which was a surprise to the RAF because they hadn't tested captured aircraft at high altitude because they didn't have oxygen bottles that fitted the aircraft.

[irR4tiOn4L]

Originally Posted by Igo kyu

No.

What is said is that the RAF lacked oxygen bottles with connectors compatible with Luftwaffe oxygen systems.

Without oxygen, 18,000 ft is a hard ceiling for pilots, and even 17,000 is iffy.

IIRC it turned out that the 109 was much better than the Spitfire at very high altitudes, which was a surprise to the RAF because they hadn't tested captured aircraft at high altitude because they didn't have oxygen bottles that fitted the aircraft.

Thanks for that clarification, the pilot's notes didn't make that clear as far as I could see - only said "owing to the absence of oxygen apparatus in the M.E. 109".

My other points stand though I suppose.

[Robo.]

Originally Posted by Igo kyu

IIRC it turned out that the 109 was much better than the Spitfire at very high altitudes, which was a surprise to the RAF because they hadn't tested captured aircraft at high altitude because they didn't have oxygen bottles that fitted the aircraft.

Ah, makes sense. I thought though that Merlin performed better than DB higher up due to higher full throttle height and supercharger designs of bothe engines. I might be wrong but it seems that above 16.500 feet, the Spitfire was faster than the 109 even with 87 octan fuel and also climb performance was slightly better. It was later Spitfire marks and Friedrichs where I've read accounts of Germans being some 2000ft higher and RAF unable to climb any further but I was not aware of any advantage of the Emil over early Spitfire marks. If you could point me out to some sources that would be great!

[Kurfürst]

Originally Posted by Robo.

Ah, makes sense. I thought though that Merlin performed better than DB higher up due to higher full throttle height and supercharger designs of bothe engines. I might be wrong but it seems that above 16.500 feet, the Spitfire was faster than the 109 even with 87 octan fuel and also climb performance was slightly better. It was later Spitfire marks and Friedrichs where I've read accounts of Germans being some 2000ft higher and RAF unable to climb any further but I was not aware of any advantage of the Emil over early Spitfire marks. If you could point me out to some sources that would be great!

Depends. The Spitfire in the period of the BoB went on with just two Merlin engines, the III and XII. The latter IIRC was marginally better for lower altitudes and worse for higher altitudes.

On the German side its a bit more complicated - most books will tell you that they used 'DB 601' but in reality 109s/110s had a number of DB 601 variants installed during the Battle:

DB 601A-1 with old type supercharger - this had a rated altitude of just 4000m.
DB 601A-1 with improved type supercharger - this had a rated altitude increased to 4500m.
DB 601Aa - this had increased boost pressures, which meant it developed about 10% more power than the 601A-1 below rated altitude, operating at 1.35/1.45ata instead of 1.30/1.40 ata, but similiar altitude performance. I believe this is the variant we have modelled.
DB 601N - this one was fitted to 109s and 110s and used 100 octane fuel, and had both increased boost pressures, higher compression ratio and a more powerful supercharger with a rated altitude of 4800 m. Off all engines during BoB, British or German, this had the best altitude performance. The one fitted to the 109F had a better supercharger and a rated altitude of 5200 iirc.

In addition, during the Battle the Luftwaffe cleared increased RPMs for the DB 601 A and N-series engines, and this would increase altitude performance (the supercharger's rotation speed was linked to the engine speed, so increasing the engine speed also increased the supercharger performance)

[Robo.]

Originally Posted by Kurfürst

DB 601A-1 with old type supercharger - this had a rated altitude of just 4000m.
DB 601A-1 with improved type supercharger - this had a rated altitude increased to 4500m.

Interesting, I always thought that FTH was the main obvious difference between A-1 and Aa versions.

I am not too sure about the develompemt of German superchargers but from what I remember the A-0 (not used in the sim or during the BoB in the 109s) has had FTH of 4000m, then improved supercharger of A-1 made it to 4500m. 601 Aa was at 4000m again with better low alt performance instead. I am bit confused here with what you're saying.

Still, early Merlins had higher FTH than any of the above engines, hence my assumption the RAF had slight advantage at high alt.

DB 601Aa - this had increased boost pressures, which meant it developed about 10% more power than the 601A-1 below rated altitude, operating at 1.35/1.45ata instead of 1.30/1.40 ata, but similiar altitude performance. I believe this is the variant we have modelled.

The DB 601A we've got in game is appartently modelled at 1020PS so I suppose it's the A-1 version with FHT at 4500m.

Originally Posted by Kurfürst

DB 601N

We haven't got this one modelled (perhaps better to compare with Merlin XX at slightly later stage of the conflict), there are no E-4/N (or E-7/N) or Hurricane Mk.II in the sim.

[justme262]

I still don't understand... let me get this straight

Ok I'm in a BF109 diving at high speed on a hurricane with neutral trim and forward pressure on the stick to hold the nose down, he sees me and breaks right. I roll right and pull back on the stick gradually accelerating the turn and increasing the angle of attack till eventually one wing or the other stalls and I spin. Does trimming the whole horizontal stabilizer delay the high speed stall? Can my plane achieved greater angle of attack with the stabilizer trimmed by wheel compared to the elevator raised by stick?
If either way I reach same maximum angle of attack and stall in same place then what's the difference?

In real life the elevator forces go up at high speed so I can see an advantage to a pilot trimming the nose up at high speed but in this "sim" none of the fighters have heavy controls at high speed so why not just pull back on the stick.

[Kurfürst]

Originally Posted by Robo.

Interesting, I always thought that FTH was the main obvious difference between A-1 and Aa versions.

I am not too sure about the develompemt of German superchargers but from what I remember the A-0 (not used in the sim or during the BoB in the 109s) has had FTH of 4000m, then improved supercharger of A-1 made it to 4500m. 601 Aa was at 4000m again with better low alt performance instead. I am bit confused here with what you're saying.

Still, early Merlins had higher FTH than any of the above engines, hence my assumption the RAF had slight advantage at high alt.

It's mind dazzling, I agree.

http://kurfurst.org/Engine/DB60x/DB6...sheets_A1.html
http://kurfurst.org/Engine/DB60x/DB6...sheets_Aa.html

I did check my references. It seems that that Aa had the new type of Lader, it just had higher boosts, which can be maintained to lower altitudes only of course, and so seemingly the high altitude performance is worse than A-1 with new Lader.

However checking the power curves show that the A-1/new Lader has very similiar, practically the same altitude performance.



ie. at SL

DB 601A-1 with old Lader: 990 PS (1.3 / 2400 rpm), 1100 PS (1.40 / 2500 rpm)
DB 601A-1 with new Lader: 990 PS (1.3 / 2400 rpm), 1100 PS (1.40 / 2500 rpm)
DB 601Aa: 1045 PS (1.35 / 2400 rpm), 1175 Ps (1.45 / 2500 rpm)
DB 601N: 1175 PS (1.35 / 2600 rpm)

Merlin III: 880 HP (+ 6 1/4 lbs / 3000 )
Merlin III: 1180 HP (+ 12 lbs / 3000 )
Merlin XII: 990 HP (+ 9 lbs / 3000 )
Merlin XII: 1165 HP (+ 12 lbs / 3000 )

So at SL the Aa is a bit more powerful, the Merlin can only keep up with 100 octane.

4.5 km - this is the FTH of the A-1/new Lader

DB 601A-1 with old Lader: 960 PS (1.3 / 2400 rpm)
DB 601A-1 with new Lader: 1020 PS (1.3 / 2400 rpm)
DB 601Aa: 1000 PS (1.35 / 2400 rpm)
601N, Emil version with lower FTH: 1050 PS

Merlin III: 1015 HP (+ 6 1/4 lbs / 3000 )
Merlin III: 1080 HP (+ 12 lbs / 3000 )
Merlin XII: 1140 HP (+ 9 lbs / 3000 )

Essentially there is very little difference between these engines at the most common BoB fighting height, the 601A with the old lader is a bit poorer, the others are essentially the same. The Merlin XII is the best for these altitudes.

at 7 km (23 000 feet)
DB 601A-1 with old Lader: 705 PS (1.3 / 2400 rpm)
DB 601A-1 with new Lader: 750 PS (1.3 / 2400 rpm)
DB 601Aa: 725 PS (1.35 / 2400)
601N, Emil version with lower FTH: 920 PS (1.35 / 2600)

Merlin III: 780 HP (+ 6 1/4 lbs / 3000 )
Merlin XII: 830 HP (+ 9 lbs / 3000 )

So if we go higher we find the 601A with the old Lader was not competitive, but the new one was practically the same as the Merlin III.

Te rare Merlin XII and 601N trump all the others, the 601N being the best engine at altitude by far.

Originally Posted by Robo.

DB 601Aa - this had increased boost pressures, which meant it developed about 10% more power than the 601A-1 below rated altitude, operating at 1.35/1.45ata instead of 1.30/1.40 ata, but similiar altitude performance. I believe this is the variant we have modelled.

The DB 601A we've got in game is appartently modelled at 1020PS so I suppose it's the A-1 version with FHT at 4500m.

We haven't got this one modelled (perhaps better to compare with Merlin XX at slightly later stage of the conflict), there are no E-4/N (or E-7/N) or Hurricane Mk.II in the sim.

I was going by the 1.35/1.45ata rating, which would point to the Aa. 1020 PS may well point to the A-1 however, its the A-1's rating at altitude.

I haven't seen the data files myself however, just one post on the board. Can you PM me how to extract these? Thx!

[Robo.]

Originally Posted by irR4tiOn4L

That was in a dive, where the 109's controls were all very heavy! That is not representative of how heavy the trim might be in a horizontal maneuver. Additionally, others have said the large wheel made it easier than competing designs, and I don't think we should be looking at the 109 trim in isolation.

I agree, but from the accounts and the above video it would seem that although being big, it was not very fast in adjusting the trim. Also, comparing the 109 design to competing designs (with trimtabs), it was rather different and more effective as such (with more surface to work with), although slower and more difficult to operate at higher speeds - adjustments would happen in jumps and it would not be easy to trim when the speed has buit up already. Also, French tests mention that even vertical manoeveurs trim was needed where D.520 could easily turn with the stick only etc.

Originally Posted by irR4tiOn4L

What SHOULD be taken into accound in CLOD, and is not, however, is the reputed heaviness of the 109's controls in a dive. I've never had to use trim to pull out of a high speed dive in CLOD, and I feel that I should.

My point precisely. Not in a dive I would say but at high speed even in horizontal flight. The behaviour in the dive had nothing to do with the compresibility effect, it was purely loss of effectivity as the speed build up afik. On full real settings I would expect to need to trim before I enter the dive otherwise I would encounter difficulties. I would expect the trim control to be slower (and heavier IRL) as the speed is rising. In the sim I can get full nose up at any speed with the move of my thumb, the aircraft reacts immediately and too swift leading to unrealistic manoeveurs.

The 109 was very agile in the hands of a good and experienced pilot and is more difficult to master than some other designs. This is sort of the case in the game already (at least that's how I see it), one thing that ruins this for me is the trim and few other things that make flying the 109 much less challenging. But let's stay with the trim:

1. THE RANGE. The real thing had the range of 12 degrees from -3 to +8 degrees, neutral being 0, (Take off setting was between 0-1). The indicator and the range is correct BUT it seems to me that the neutral position is not 0 in game. It seems the range is symetrical, therefore the neutral position is at 3. If you set your elevator trim to 0, that will lead to nose-heavy situation in the sim. I believe the 109 should have more range in tail-heavy direction.

2. THE SPEED AND RESPONSE - asstated above, the animation in the sim is certainly wrong (see RAE test quoted beforehand) and the speed and response is too swift as I mentioned earlier. I would expect the trimming becoming more difficult (slower) at higher speeds and ideally, we would have adjustments in 'jumps' as mentioned by Finnish pilots re. hand placement and movement. Anything would be better that what we've got now imho.

Originally Posted by irR4tiOn4L

What is also interesting out of your linked notes is that the 109 lacked oxygen gear - would this result in a higher effective ceiling for the red fighters?

This is most certainly wrong, the 109 has had oxygen equipement as a very modern fighter. Perhaps that particular machine (damaged and acaptured iirc) had it removed or they have had no mask or compatible exuipement to refill it or similar reason, but the oxygen bottle is down on your right hand side with the breather tube and hoses and gauges (blue for oxygen in LW cockpits).

Originally Posted by irR4tiOn4L

Extremely interesting also is the pilot's notes on the tendency of the Hurricane pilot to black out where the 109 pilot would not. Initially I read this as pulling more G's, but in actuality, they are saying that the pilots of a hurricane sat more vertically and had a tendency to black out even in similar g maneuvers! I definitely don't see blackout tendencies modelled in the sim, and that would make it rather interesting, wouldn't it, if the 109's pilots could sustain more g without blacking out!

This is very interesting and important point. I know nothing about pilot's position in the cockpit regarding blackout. The only thing I recall is that in the Spitfire, the pilot was able to lift his feet from the rudder and rest them on a horizontal bar. Apparently that would also make pulling high Gs easier and I've heard on many accounts that the position in the cockpit was very important.

The difference between Hurricane and 109 should be considered in the sim.