Project Martin A-30 Baltimore

Hello Ivan,

Well, don´t worry about it. I didn´t get upset about it and just took it in my stride, and I didn´t see the post you say you got Smilo to delete. It was NOT like Mudpond´s AirEd.ini that destroyed my AirEd Installation for a number of days (I don´t mean the newest AirEd.ini with the upgraded parameter names...), so I suppose that a bit of criticism IS justified in that case..!!

Then, I also re-edit posts a lot, not only to add additional information that will save posting another post, but also when I realize I have misunderstand something and have to change something I have answered, and I rush back to the computer barely in time before the 400 minutes are up, to edit out some frustrated comment of mine which is not applicable and out of place anyway! So it happens to us all. I think that was what you were referring to. With my bad memory it has taken a while to remember...

I saw the Minimum Governed RPM comment in the new AirEd.ini, about it controlling AF99 Prop animation, and was thinking of trying out something later on. Sounds interesting.

The Mk.IIIA .air file still needs toning down a little, but it´s slowly also getting there!
.
I´ve never been to Lisbon, and they say it´s quite beautiful. I hobe your Anna Honey enjoyed it. The Europeans are very fond of their Port Wine. Here on the Canary Islands there is a slightly stronger and more aromatic variety (because there´s more sun) of this sweet wine called Malvasía, which is truly excellent!

Cheers,
Aleatorylamp
 
Actually I had never seen the comments in AirEd.ini on this subject but will look for them when I get the chance.
I had always thought that I was the first to experiment with them.
Once I had a workable solution, I probably would not have been looking for an alternate description.
That just goes to prove that there really isn't much that is new.

Perhaps this WEP Additional Boost Gain isn't new either?

I have a bunch of experiments in mind, but have way too many distractions at the moment to get anything significant done....

- Ivan.
 
Hello Ivan,

Do check your e-mail for an off topic subject completely unrelated to this one, which may be of some value to you.

Both parameters available in AirEd, in the new .ini called Emergency Boost MP Offset and Emergency Boost MP Gain Offset, and in the older .ini called Press Change Rate and Pressure Increase, are nowhere to be found in FDEditor, so they must both be newer than FDEditor. If you want, I can send you the older .ini file.

Must get to sleep!
Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

I sent the information to my sister. I will also do some checking. The actual problem possibly is a bit different than one might expect.

Regarding AirEd.ini, I found that my copy was pretty old as well. It is newer than the one that comes with AirEd, but still dates back to around 2003 or so. I just did a quick search and found one dating back to 2012 but have not had a chance to look it over for comparison yet.

- Ivan.
 
Hello Ivan,
I hope it helps anyway.

I had a short look at the newest 2012 air.ini and it has no help info comments on parameters for the old simulators, because it is intended for use with the new ones, and these parameters are all marked as "obsolete", which may be even more confusing for us, or at least irritating, when you are using the program.

The parameter titles it it, however, seem to be very much the same as in the .air file that comes with the program and dates from 2006. This one does have quite a lot more info files, and although investigation at that time was more for the newer simulators, the older ones seem to have been taken into account for comparison purposes, so this .ini file is probably the most useful.

The old one I am using is from 2000, and may be quite similar to the 2003 one you have. As you commented earlier, there was rather more limited knowledge available at that time, so some of the info files could contain outdated information.

But the thought still remains... The newer simulators started transferring more and more control into the aircraft.cfg file, so investigation on the effects of older .air file parameters on the older simulators may still not be complete.

Another thing on the Mudpond aired.ini file: It is intended for an .air file editor called AirWrench, so why didn´t they call it AirWr.ini? There is no reference to that respect in the .ini file itself, so if you have it "lying around near" your AirEd and use it there, it will be a great headache. On the other hand, yet another .air file Editor called AAM also uses the aired.ini file, but its use with AirEd causes no problems, so I would say that the Mudpond people could have issued some kind of warning to this respect.

Cheers,
Aleatorylamp
 
Hello Ivan,
I noticed on the second B-25 Engine description, the yellowish one, that S.L. normal Horsepower was 1500 Hp, and Take-off was 1700 Hp. So there was a 200 Hp difference, and I only have about 35 Hp difference.
I´m going to try and reduce the present normal power of 1565 Hp at S.L. to 1500 Hp, maintaining 1700 Hp for Maximum Take-off.
So, by adjusting Boost Gain from 1500 Hp, and not from 1600 Hp, maybe the curve will behave a little better!"
Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

I have experimented a bit with Air Wrench, but have never been that interested because I am really interested not so much in having a program build the AIR file for me, but rather to know how to do it myself.

Regarding the B-25 "Normal" Horsepower, one has to wonder which rating is being described and what the manifold pressure actually was.
Without that, it really gives no additional information.

- Ivan.
 
Simulator or Similator (!!)

Hello Ivan,
Yes, same here as regards Air Wrench although I never got it because I can´t use a spread sheet very well anyway, except to put in test and exam marks and calculate the final marks for my students!

Regarding the R-2600-13/29, it IS like you say: The lack of further data on manifold pressure values are making it difficult to increase the difference between normal power and take-off power to 200 Hp, i.e. 1500 Hp to 1700 Hp. Without the normal power S.L. Hg value, all that occurrs to me is to try experiment with lower values to see what happens.

If Maximum Continuous is at 38 Hg at 6700 ft with low blower, and 39 Hg at 13000-15000 ft with High blower, then maybe a single-speed blower approximation would be 39 or 40 Hg for Sea Level.
If that´s not enough, I could always reduce it until I get a satisfactory difference, and then see what happens higher up.

Being a simulator, something similar to reality should come out.
Maybe we can then call it a "Similator"!! Ha ha!

I´ll see if anything useful can be done!

Update:
--------
Surprise, SURPRISE!: Something useful HAS appeared:
I just went back to the latest normal-style best result .air file I got for the Mk.V, but this time left everything as it was except for reducing the Normal Max. MP value to 40, and raising the WEP MP increase to 4 Hg.
This way the Total Max. Hg is 44. I could hardly believe it!:
At 500 ft it read 1502 Hp with 40 Hg (normal), and 1707 Hp with 44 Hg (WEP)!
So we have a "Similator", which we can use to make deductions on data missing from specifications, maybe?

Cheers,
Aleatorylamp
 
Good accuracy at low and medium altitudes

Hello Ivan,
Further to the Baltimore Mk.V .air file I´m testing for curve-similitude with R-2600-13 SEFC specs, I found several other other points below critical altitude that coincide rather well at different throttle % positions with the desired Mp values.

I thought this was very pleasing! These include MP and Power settings for other operating conditions: Economical Maximum, Minimum Specific Consumption and Minimum Cruising (between 500 ft and 6700 ft).

You had mentioned in your tutorial and on other occasions that CFS was very good below critical altitude, and this only corroborates it! Higher up, also as you had commented, we can only go for the best approximations, and we have seen the results as being quite acceptable for this .air file.

I was debating whether or not to include the 5-minute Military Power with its 42 Hg into WEP. For the moment, and following your idea, it is within the normal procedural throttle settings so as to give a little excitement to the game, and I´d feel inclined to leave it there unless you have second thoughts about this.

Cheers,
Aleatorylamp
 
Last edited:
Hello Aleatorylamp,

I am not so sure about "very good" below critical altitude.
I would now state it as "very predictable" at most altitudes.
That does not mean it is necessarily a good match at medium altitudes as was shown with the FW 190D.

As I stated before here in this thread:
You know the WEP Limitations of CFS.
I do not believe that they have a great resemblance to reality other than where a power adder of some kind is used.
The question is whether or not "Normal Maximum" should be restricted in duration.
I think it should not, but it really is a matter of opinion.
The limits are either WEP limits or none at all.

It is your choice here, not mine. I made my choice on MY project and you know everything I did.

- Ivan.
 
Normal and Emergency Maximum

Hello Ivan,
I don´t understand it very well. You mention Normal Maximum - i.e. Maximum Continuous?
This is at 1500 Hp and 38 Hg for 6700 ft, and 1350 Hp and 39 Hg for 15,000 ft in the SEFC.
It is called Maximum Contiuous, which unless I am mistaken, we have never questioned.

The 5-minute Emergency Maximum or Militatry Power is at 1700 Hp and 42 Hg for 4500 ft, and 1700 Hp and 41 Hg for 15000 ft in the SEFC. At the moment, this is what is now is UNrestricted in the .air file, despite being a 5-minute affair, and was the reason for my question. Anyway, for the sake of gaming it is better, and now we only have the full 44 Hg Take-off Power in WEP.

Low and Medium Altitude performance:
For some extra .air file trials with the Economical Maximum and other operating conditions, provisionally, I placed Military Power into WEP, so WEP controlled MP at 41-44 Hg instead of only at 42-44 Hg. I wanted to calibrate lower throttle positions in % to correlate with the lower MP readings and powers.
The comparison between what the SEFC stated and what the CFS .air file did, was quite interesting - It was much better than I had expected. Just in case you are interested, these were the results.

Percentage indications are throttle positions. For these tests, WEP includes MP from 41 to 44 Hg.

At 500 Ft:
---------------
SEFC:
1700 Hp, 44.0 Hg (Max Take-Off)
1500 Hp, 40.0 Hg (Normal or Max Continuous, Exact MP estimated).
Baltimore Mk.V:
100%: 1706 Hp, 44.0 Hg, 293.6 mph
100%: 1502 Hp, 40.0 Hg, 281.4 mph
Comments: Reasonably close.

At 4500 ft (Military Power)
--------------
SEFC: 1700 Hp, 42.0 Hg
Baltimore Mk.V:
96% : 1705 Hp, 42.7 Hg, 303.2 mph
95% : 1672 Hp, 42.1 Hg, 300.8 mph
Comments: Quite close.
100%:1771 Hp, 44.0 Hg, 307.0 mph (Max. Power not quoted in SEFC)

At 5500 ft (Emergency Max or Military)
--------------
SEFC:1700 Hp, 42.0 Hg (Hg expected but not quoted in the other "yellowish" SEFC)
Baltimore Mk.V:
96% : 1704 Hp, 42.1 Hg, 306 mph

At 6700 ft
--------------
SEFC:
1500 Hp, 38.0 Hg (Max Continuous)
1125 Hp, 31.5 Hg (Economical Max)
1005 Hp, 29.5 Hg (Min Specific Consumption)
_900 Hp, 27.0 Hg (Min Cruising)
Baltimore Mk.V:
95% : 1495 Hp, 38.1 Hg
87% : 1128 Hp, 31.2 Hg
73% : 1027 Hp, 29.4 Hg
67% : _911 Hp, 27.2 Hg

The .air file then, will stay with 44 Take-Off Power in WEP and Military Power outside WEP. Maximum Continuous is outside WEP anyway.

Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

Regarding "Normal Maximum", I was intending it to mean the non-WEP maximum.
I believe it would be the 42.0 inches Hg setting.
So is this considered WEP in CFS or just the maximum non-WEP setting?

Regarding the rest of your settings, I do not see how having a match to the SEFC at 94% or 95% throttle is useful.
How can you prevent the player from using 100%?

- Ivan.
 
Hello Ivan,
OK thanks, no problem, then it is the military power setting at 42 Hg that you meant.

>So is this considered WEP in CFS or just the maximum non-WEP setting?<
A good question, your question, that´s why I mentioned it.
On the real plane, it was a 5-minute affair too, as was the 41 Hg power at 12000 ft., but as we are playing a game, we have poetic license to put it in wherever we want. There is only one WEP setting, so on one hand it is impractical to have to adjust from 44 down to 42 Hg with the throttle, if we want military power, (Key 9 is not not enough for 94%), and on the other hand, with 42 Hg outside WEP, players can use it all the time... so at the end, I would agree with you, that WEP should only be the 44 Hg for Take-off...

Showing the different matches for the MP Hg readings at different throttle % positions was not intended for players to use. I only wanted to show how CFS is surprisingly accurate for Hp-MP readings from S.L. to 6700 ft, meaning that we have done a good job with the .air file (but OK, we already knew it was a good .air file).

However, to show the discrepancies between SEFC and CFS performance numbers for heights further up, wouldn´t show anything, as we already know about the peak below the estimated engine criticial-altitude and the 100-200 hp differences above the aircraft´s critical-altitude.

Incidentally, I have found a free .pdf book called "Alamein to the Alps" about the RAAF Squadrons in Africa and in Greece, who used the Baltimore after the Blenheims. Apart from being a tribute to those airmen, with detailed acounts of missions which are interesting but quite distressing, there is a technical description as of page 33. It appears that the Mk.IIIA and Mk.IV units were used and that the engine was the R-2600-19 (an improvement over the -13, but not as good as the -29). Performance was similar to the -13, and there is a description of a shallow dive at a screaming 300 mph. So for these models, obviously, horizontal flight at 305 mph was peak performance - the 5-minute thing.
Another interesting thing is that they describe maximum fuel efficiency at 165 mph with 24 Hg. (Being a lighter plane than the Mitchell, it would tie in quite nicely).
Then they said they could outrun the Me 109 ´s by 100 mph, but at the expense of almost doubling their fuel consumption from 184 to 320 gal/hr, which meant that they would not be able to get back to home base but would have to ditch, so they had to use evasive maneuvers and their powerful defensive armament.

Anyway...
Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

I know about the unwanted peak in engine output about 2/3 between Sea Level and Critical Altitude, but I don't know about the 100-200 HP ABOVE critical altitude. I am really not sure what you are describing here.

We still have no idea how good the AIR file is.
So far, all we know is that the engine output is "Fairly Reasonable" within the limits of Combat Flight Simulator.
Engine Performance is only a small part of the AIR file even though it affects so many things.
There are still many many other issues that need to be addressed.
Unfortunately, most of those things that need to be addressed can only be tested subjectively.

My understanding of the R-2600 series of engines is that the -13 and -29 are pretty much equivalent.
The aircraft manuals for the B-25 Mitchell directly state this.
The -19 was a lower powered version from what I have found thus far.

Regarding reaching 300 MPH in a shallow dive, the question you should as is whether this was True Air Speed or Indicated Air Speed.
Depending on the altitude, 300 MPH IAS could be quite fast.
Outrunning ANY model of the Messerschmitt 109 by 100 MPH is pure hyperbole.
Just look at the numbers and see if they make sense for this account to be true.
The only Allied "Bomber" I can think of that had even a small hope of doing this in level flight would have been the DeHavilland Mosquito and it would have to be a very early Me 109 that was pursuing.

Regarding defensive armament, my opinion is that the Baltimore fits into the mediocre category.
In what manner was its armament "Powerful"???

- Ivan.
 
Hello Ivan,

Thanks for your answers and comments. Yes, you are right about the lower power of the -19 compared to the -13 and -29, because it gave1660 Hp. The coment in the book that it was an improvement referred to the 1600 Hp GR2600-A5B predecessor engines of the MkI/II. Sorry about the confusion!

Anyway, the research in itself is proving very interesting, and we are still limited to deductions and comparisons with the SFEC´s that you have provided, in order to reach any kind of possibly better conclusions. That´s also why I continually come back with comments and questions, in order to bounce off ideas, which I hope will be interesting for you too!

I will need some time to answer your questions as the .pdf book I have found is very long and there are several parts I have to copy out - the .pdf does not allow cutting and pasting!

There are 221 pages, and I made a .txt copy, but I don´t know if that´s even worse to find something.

http://www.454-459squadrons.org.au/d...the%20Alps.pdf

Anyway, I´ll see what I can do!

Cheers,
Aleatorylamp
 
Hello Ivan,
About your question on the air speed:
The .pdf book mentions, during an account of a reconnaissance mission:
"We find at about a thousand feet, that 24 inches of boost, 1650 rpm will give us 165 miles an hour Indicated Air Speed, and aconsumption of 84 gallons an hour. This is our most economical cruising, and makes a safety range of three-and-three-quarter hours, calculating safety range to be eighty-two percent of the absolute maximum."

Then, my comment on a Baltimore outrunning an Me109 by 100 mph must be completely wrong. I must have seriously got confused with something in the text there! Ever so sorry... Some hyperbole...!!

The following may also be of interest to Smilo:
I cut and pasted some of the relevant text from the .pdf book.

One of the attached text files contains information from the .pdf text regarding the development of the defensive armament on the Baltimore Models, and two stories about being attacked by Me 109´s.

The other text file contains a description of the Mk.IIIA and Mk.IV, as well as test results reporting flaws of the earlier models. Later on, the .pdf mentions rudder problems on the Mk.V, and how they were replaced with scavenged older rudders at the air base (not in the attached texts).

Enjoy!
Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

At low altitudes, the Baltimore COULD probably outrun a Me 109E and give a Me 109F a pretty good chase.
It would have no hope against the Me 109G or anything later though.
Please note that the 109 did not carry all that much fuel either, so at full power, the late versions would go completely dry in a bit over a half hour.
Earlier versions were better but not that much better. (Figure on 45 minutes to 1 hour at high power settings.)

I have always wondered if the prohibition of a Luftwaffe after the Great War managed to cripple German Aircraft designs in less than obvious ways; if one only designs gliders, then thinking of a good location for fuel isn't a great concern.

Regarding the accounts of fighting off Me 109s:
Note that only ONE Me 109 was downed and perhaps two were damaged.
Obviously if a bomber were shot down, its crew would not be reporting the outcome of the attack.

The Me 109 in any version except the "cannon boats" were adequately armed only for fighter combat.
The heavy structure of a larger plane was much harder to destroy.
This was recognized by the Luftwaffe which is why they mounted gondola weapons on bomber interceptors.
In general with the exception of the Macchi C.205 Veltro in later versions, the Italian fighters were also too lightly armed for bomber intercepts.
Two machine guns are not really enough for a good bomber interceptor.

- Ivan.
 
Hello Ivan,
I see. Very interesting indeed!

Another curious thing mentioned in the book is that some attacks were carried out by Me109 aircraft with long range tanks, but the knowledge about them had to be kept secret, and was fortunately not widespread. This was because some crews ended up as POW´s, and during interrogation, were not to say that they had seen such aircraft, as it would have given away the fact that they were snooping around in a location given to them by British Intelligence, whose information came from the decyphering of the Enigma Code.

Anyway, let´s see how the rest of the two .air files comes out - like you say, the engine isn´t the only thing.

Tomorrow is my daughter´s graduation ceremony, and hopefully I´ll get my 32-year-old car back from the electrician´s - there´s a mess with the useless electronic module that controlls, of all things, also the indicator lights and the dashboard instruments, damaged through a short circuit in the reverse-light switch thanks to more stupidity of my previous mechanic. This has now combined with a problem on the the ignition-switch starter-connections, and perhaps I´ll get the car back in time for tomorrow... You can imagine how everyone is blaming me in the house for this... The electrician is installing a separate starter button and trying to adapt a scavenged instrument cluster, as an original replacement for it costs several thousand dollars - only the burnt-out speedometer is 1200 dollars!! They can eat it. If the electrician can´t do anything, I´ll see how I can re-wire the indicator lights onto a separate circuit to work independantly from the stupid dash-coard computer that really does nothing useful anyway - ignition is mechanically controlled by the injection pump anyway!

Cheers,
Aleatorylamp
 
I really did not understand your meaning of attacks by Me 109s with long range tanks.
The typical Me 109, especially late in the war tended to fly often with drop tanks because their internal fuel capacity was so little.

- Ivan.
 
Hello Ivan,

As fas as I can understand from reading the .pdf book, it appears that in North Africa, the Baltimores were doing photographic recon somewhere, following instructions from British Intelligence, who were deciphering German radio communications coded with the Enigma, or Purple Machine. (Alan Turing...)

The Baltimores had their own 300 imp. gal) long range tanks fitted in the belly (no bombs), and a few had encounters with Me109 aircraft with long range tanks - or drop tanks.

If forced to ditch and then captured and sent to the Stalag Luft camps, they were not to mention during interrogation that they had seen Me109´s with long range tanks, as it would have given away the fact that they were snooping around somewhere where the Me109´s had to go with long range tanks, giving away the fact that the English knew about the location of what they were looking for. The English had to keep their deciphering of the Enigma Code secret.

Cheers,
Aleatorylamp
 
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