aleatorylamp
Charter Member
Hello Ivan,
I hope you enjoyed your guests!
With Yaw-Roll coupling, do you mean Adverse Yaw or perhaps Roll Moment due to ailerons? Is this because of the dihedral on the Baltimore, that the MitchellC didn´t have?
I haven´t done much flying with the plane so I don´t know what it feels like yet, but I´ll see.
I think I understood most of the Engine Tuning Tutorial, although perhaps not perfectly.
My main problem was adjusting the increased power after reducing the MitchellC´s 12.58 ft propeller blades to the Baltimore´s 11 ft ones. Obviously I didn´t want to fiddle with the propeller tables!
I did indeed adjust friction and torque graphs for the SL performance first, at 44 Mpsi and 2600 RPM, but I had to keep the Hp on the low side, like it is on the MitchellC .air file, so as not to get far too much power at altitude. Hence no 1700 Hp.
I left the critical altitude as 12500 ft as it was in the MitchellC file. I found no reference to it in any sources. I suppose I could adjust that too, but what to? The 2-speed single blower had L and H settings, depending on altitude. Maybe L below 9000 ft and H above? I don´t know, but it won´t work for CFS1 anyway. I suppose critical altitude could be anything from 10000 to 12500.
Then, the problem with adjusting friction and torque again for higher altitude was that it affects the SL performance too, so had to do it a different way. As I´d read about the boost gain in the Tuning Tutorial, I applied that, and I think it worked rather well. As you stated in your last post, you are absolutely right, it was the best thing to do, although it did take me some time to realize!
Yes, I noticed the choices you´d made, and why, as regards as regards Sea Level Power and Critical Altitude Power - they are both a little lower.
In my case I couldn´t curb a small surge in speed at critical altitude, but on the other hand, at 15000 ft performance is more correct.
I read about the basically similar Martin 167 Maryland, with its 1050 Hp engines, its tight fuselage and the same bomb-load, and how the Baltimore was developed from it. It had the same wings, but a deeper fuselage, to enable the crew to move around inside, although it was still very cramped. Then, the higher 1600 hp engine power gave better performance, even more when the engines were upgraded to 1660 hp, and finally to 1700 hp ones.
Both models seem to have been built for the East-European theater. I suppose the Americans didn´t want to use them because they were developing the Mitchell and the Marauder, which they liked more. Also I noticed that initially the designation A-30 was for the Maryland... However, I haven´t got enough time to provide a summary of the aircraft´s development history, or speculating too much about it - I don´t know enough.
Working on the .air file is still a bit confusing. I still don´t understand why we are using 284 mph max. speed at Sea-Level, as this does not appear anywhere in the sources, but I accept it gladly because you know much more about the subject than I do!
Anyway, after getting the .air file into a more or less acceptable state, I want to get on with actually building the plane. At the moment it´s only a cardboard model made with 2D templates like a toy - enough for .air file tuning, though!
Cheers,
Aleatorylamp
I hope you enjoyed your guests!
With Yaw-Roll coupling, do you mean Adverse Yaw or perhaps Roll Moment due to ailerons? Is this because of the dihedral on the Baltimore, that the MitchellC didn´t have?
I haven´t done much flying with the plane so I don´t know what it feels like yet, but I´ll see.
I think I understood most of the Engine Tuning Tutorial, although perhaps not perfectly.
My main problem was adjusting the increased power after reducing the MitchellC´s 12.58 ft propeller blades to the Baltimore´s 11 ft ones. Obviously I didn´t want to fiddle with the propeller tables!
I did indeed adjust friction and torque graphs for the SL performance first, at 44 Mpsi and 2600 RPM, but I had to keep the Hp on the low side, like it is on the MitchellC .air file, so as not to get far too much power at altitude. Hence no 1700 Hp.
I left the critical altitude as 12500 ft as it was in the MitchellC file. I found no reference to it in any sources. I suppose I could adjust that too, but what to? The 2-speed single blower had L and H settings, depending on altitude. Maybe L below 9000 ft and H above? I don´t know, but it won´t work for CFS1 anyway. I suppose critical altitude could be anything from 10000 to 12500.
Then, the problem with adjusting friction and torque again for higher altitude was that it affects the SL performance too, so had to do it a different way. As I´d read about the boost gain in the Tuning Tutorial, I applied that, and I think it worked rather well. As you stated in your last post, you are absolutely right, it was the best thing to do, although it did take me some time to realize!
Yes, I noticed the choices you´d made, and why, as regards as regards Sea Level Power and Critical Altitude Power - they are both a little lower.
In my case I couldn´t curb a small surge in speed at critical altitude, but on the other hand, at 15000 ft performance is more correct.
I read about the basically similar Martin 167 Maryland, with its 1050 Hp engines, its tight fuselage and the same bomb-load, and how the Baltimore was developed from it. It had the same wings, but a deeper fuselage, to enable the crew to move around inside, although it was still very cramped. Then, the higher 1600 hp engine power gave better performance, even more when the engines were upgraded to 1660 hp, and finally to 1700 hp ones.
Both models seem to have been built for the East-European theater. I suppose the Americans didn´t want to use them because they were developing the Mitchell and the Marauder, which they liked more. Also I noticed that initially the designation A-30 was for the Maryland... However, I haven´t got enough time to provide a summary of the aircraft´s development history, or speculating too much about it - I don´t know enough.
Working on the .air file is still a bit confusing. I still don´t understand why we are using 284 mph max. speed at Sea-Level, as this does not appear anywhere in the sources, but I accept it gladly because you know much more about the subject than I do!
Anyway, after getting the .air file into a more or less acceptable state, I want to get on with actually building the plane. At the moment it´s only a cardboard model made with 2D templates like a toy - enough for .air file tuning, though!
Cheers,
Aleatorylamp
