B26 climbing performance during full missions with take off with different bomb loads

[kraut1]

Hi,

I am currently working on a EMG mod for with long range bomber escort missions for whole Rheinland map area.

I have observed, that B26 seems to have a very poor climbing performance even with the reduced bomb load (4xM64) and 70% fuel.

 

I have already created working mods to improve this, but I would like to know if you have the same opinion about about the climbing performance?

And it would be very interesting for me to get some historical information, at least 1 or 2 examples about the real max. altitudes for operations with bomb loads + fuel.

 

Currently with the reduced bomb load (4xM64) and ca. 70% fuel the max. altitude seems to be only ca. 3500...4000m with the default settings?

With my current working modification it is possible to reach ca. 19300ft / 5880m with 4xM64 / 70% fuel.

Edited April 25 by kraut1

[Stonehouse]

I have a few of the pilot manuals, I understand our B26 was a longer wing version so presumably had better climb characteristics. Note that the engine quoted in the IL2 encyclopedia appears to be incorrect as it is given as the R-1830-92 which is the DC3s engine. Not sure if this is an issue or not.

 

 

Climb data by engine type:

 

 

According to the B26b55 file the climb speed is 240 somethings... not sure if it is mph or knots or kph. Comment in English is "Recommended Instrumented Speed of Climb" which based on the charts seems high regardless of the units. 240 kph to knots is 208 knots. 

 

One interesting thing which seems possibly buggy is the climb times in the AI files for the B26B55, note the Climbtime to 7000m is 225 secs. Looking at the B25 I believe this 225 is a typo and should be probably 2250-2259 secs. (B25 takes 2160 secs to get to 7400m according to its file) Maybe that is the issue?

 

  ////// ClimbTime = <float ALTITUDE>, <float TIME> // 32000lb, íîìèíàë, ñòâîðêè îòêðûòû
    ClimbTime = 0,0
    ClimbTime = 1000,153
    ClimbTime = 2000,298
    ClimbTime = 3000,463
    ClimbTime = 4000,677
    ClimbTime = 5000,917
    ClimbTime = 6000,1291
    ClimbTime = 7000,225

 

Edited April 25 by Stonehouse

[kraut1]

7 hours ago, Stonehouse said:

 

Climb data by engine type:

 

 

 

One interesting thing which seems possibly buggy is the climb times in the AI files for the B26B55, note the Climbtime to 7000m is 225 secs. Looking at the B25 I believe this 225 is a typo

 

Hi Stonehouse,

Thanks for your information!

I have to find a not too complex solution and think your data is very helpful:

What I found in your data and what is importent:

With maximum weight 40000lbs the B26 is able to climb to 15000ft in ca. 21...28minutes. I assume this for heavy bomb load and and some fuel, maybe 70%?

With ca. 30000lbs...32000lbs weight the B26 is able to climb to  20000ft in ca. 19minutes. I assume this for the leight bomb load 4xM64 + maybe 70% fuel?.

 

225 is a typo: yes, this I have seen too and estimated a value.

 

I have decided only to modify the AI file in a simple way (marked by me with kraut1):

-By deactivating engine overheating

-in the ai file some times different max. values are mentioned, I have equilized them.

max. altitude 7450m

max. cruise power 0.95

-what I have observed during flight is, that at least for the leght bomb load that is most importent for me the minimum climbing speed and the minimum cruising speed is too high (300km/h). I have reduced these values to ca. 270km/h and the corresponding speed for wingman even lower.

 

By this changes with my current mod:

For 4xM64 bomb load and 70%fuel the B26 is able to climb to maximum 19300ft (5880m) while flying a distance of 156miles to reach this altitude.

This is now at least a bit confirmed by your data that a partially loaded B26 for combat missions can reach 20000ft, thanks very much!

For EMG mission generation the practical max. altitude is from my point of view 5500m (Waypoints at 5600m).

I have created and tested (autopilot) a mission from my UK dummy airfield near Middelburg to Frankfurt and back and this works.

(by the way I am living in Maintal (marked)

 

AI changes:

caeroplane_b_26b_55-v2.zip

 

 

Edited April 25 by kraut1

[BlitzPig_EL]

I hope that the listed R 1820 engine is a typo, as it should be an R 2800. 

[Stonehouse]

Some further info.

Safe climb speed was apparently 170mph or 274 kph or 148 knots (rounded up) for the first 2000ft and then according to the charts I previously posted - I believe this is IAS. All the flight planning charts states in red warning text that you should not exceed 36500lbs gross weight and the charts only have values for up to 36000lbs.

 

Range chart for the B26B with later R2800 engines, noting that range increases with height even though TAS is decreased. 20000ft gives you lots more range

 

The B26 has two bomb bays but after issues in service early on the rear bay was permanently closed and equipment removed leaving only the forward bay for use. The weapon loadouts cleared for use are below. I assume in the chart above 2064lbs of bombs was the 20 100lbers as nothing else really calculates to something near 2064lbs. Interestingly the M64 is a 531lb bomb which isn't one mentioned as cleared. Perhaps a later field adaption considering the manual is April 25 1943 or just a simplification for gaming purposes or to avoid the cost of modelling more bombs for an AI only aircraft. The 600lb is the M32 (see here for others https://www.bulletpicker.com/bomb_-600-lb-gp_-m32.html). 

 

 

Edited April 26 by Stonehouse

[kraut1]

2 hours ago, Stonehouse said:

Some further info.

Safe climb speed was apparently 170mph or 274 kph or 148 knots (rounded up) for the first 2000ft and then according to the charts I previously posted - I believe this is IAS. All the flight planning charts states in red warning text that you should not exceed 36500lbs gross weight and the charts only have values for up to 36000lbs.

 

Range chart for the B26B with later R2800 engines, noting that range increases with height even though TAS is decreased. 20000ft gives you lots more range

 

The B26 has two bomb bays but after issues in service early on the rear bay was permanently closed and equipment removed leaving only the forward bay for use. The weapon loadouts cleared for use are below. I assume in the chart above 2064lbs of bombs was the 20 100lbers as nothing else really calculates to something near 2064lbs. Interestingly the M64 is a 531lb bomb which isn't one mentioned as cleared. Perhaps a later field adaption considering the manual is April 25 1943 or just a simplification for gaming purposes or to avoid the cost of modelling more bombs for an AI only aircraft. The 600lb is the M32 (see here for others https://www.bulletpicker.com/bomb_-600-lb-gp_-m32.html). 

 

 

Thanks very much!

I think for my long range / increased altitude settings especially the medium settings (Gross weight 33.856lbs) are relevant.

The 4xM64 of IL-2GB have a weight of round about 2000lbs and with 962 gals. fuel the range for the Rheinland map is no problem in respect of long range missions and even my increased altitude seems to be realistic.

I will use the modifications as it is and do some final tests with max. loads for standard medium altitude / medium range missions to check if the current reduced climbing / min. cruise speed settings have some negative effects. In case that there is an issue I will reduce for full full bomb load the fuel to... 465gals. chart.

 

 

[357th_KW]

The B-26 struggles to maintain altitude even with ultra-low fuel loads (25% etc).  I gave up on it and started using the B-25 instead.  It will comfortably cruise at 7000m.

[kraut1]

1 hour ago, 357th_KW said:

The B-26 struggles to maintain altitude even with ultra-low fuel loads (25% etc).  I gave up on it and started using the B-25 instead.  It will comfortably cruise at 7000m.

Yes indeed, even with only gun armament / without bombs!

With my mod, that will be included in my EMG Germany mod, the B26 is able to climb to ca. 5800m with the 4xM64 bomb load and 70% fuel.

And according to the data provided by Stonehouse this is comparable realistic.

Edited April 26 by kraut1

[Stonehouse]

@kraut1 If you can please post a simple, repeatable mission where the unmodded B26 struggles to reach its service ceiling of 7450m when it should be able to (per game files even though the climb-time table only gets to 7000m.......the B25 has climb-time table that goes to 7400.........I wonder .........was the B26 a copy and paste and tweak hence the typos like the 225..looking in winmerge quite a substantial part of the two files are the same.

 

If you can do so I will try to raise it as a release version probable bug for the devs to investigate

 

Note the comment re climb times and 32000lb for the B26. Possibly it can be related back to the chart from the manual if the times are for that gross weight. 

 

Edited April 26 by Stonehouse

[kraut1]

1 hour ago, Stonehouse said:

@kraut1 If you can please post a simple, repeatable mission where the unmodded B26 struggles to reach its service ceiling of 7450m when it should be able to (per game files even though the climb-time table only gets to 7000m.......the B25 has climb-time table that goes to 7400.........I wonder .........was the B26 a copy and paste and tweak hence the typos like the 225..looking in winmerge quite a substantial part of the two files are the same.

 

If you can do so I will try to raise it as a release version probable bug for the devs to investigate

 

Note the comment re climb times and 32000lb for the B26. Possibly it can be related back to the chart from the manual if the times are for that gross weight. 

 

Hi Stonehouse,

I have just flown a further full test mission with my mod:

P47-D22 full B26 escort mission from Florennes to a western Germany Rail Yard.

12 plane Vee B26 formation with full bomb load and 40% fuel and moderate wind and this mission worked well.

The formation was acceptable, there were no collisions.

This means my mod and EMG settings for EMG Germany are more or less completed

By the way, it was my first P47-D22 full mission, very intersting plane with the turbocharger. Engine controll is an interesting task.

 

I have tested now the whole week long range settings for escort fighters and high altitude settings for the B25 and B26.

So I need now urgently a break from these tests and have to care for some other tasks.

 

Concerning the "altitude 7450m test mission" for the issue I would use EMG v88.2 unmodified and create a B26 mission with "guns only".

But have not created this mission because I don't know if the EMG typical B26 speed = 375km/h for all waypoints including the climb is good practise for IL-2 mission design.

I would suggest to reduce for this altitude test fuel to 0.4 and only guns armament.

And maybe you reduce the speed to 300km/h similar to the climb speed in the AI file.

Either you could do this or maybe I next week.

 

Edited April 26 by kraut1

[Stonehouse]

Done and reported as an issue.