Milton

MAP FOR 75% power will depend on RPM and Altitude and the desired fuel burn (high or low) same for 65%. The engine designers always give a HP table (which by the way there are so few who can come to grips with the older PW 1830's in the flight sim world as you set RPM and MP to achieve a desired BHP output so down low this could be a low RPM and low MP but the higher you go of course you need to increase both up to a point. Another example the RAAF always operated the PW 1830 at 31"MP 2050 RPM lean in the cruise which for most altitudes gave you about 600 HP output [@154KIAS], most commercial operators would be higher).

For this engine an ideal high power output was 280 HP not the maximum 340 and a range between 280 and 180 HP was considered normal operating range.

For example you can achieve 300 plus horsepower with the following settings at different altitudes:
3400/48"
3200/44"
3000/44"
2800/41"
2600/40"


Generally I would recommend using the [following] figures for operating these aircraft:

TKOF 48" 3400 RPM
Initial Climb at 300ft 46" 3200 RPM and gear up
Second Stage at 1500ft or safe height, 40" and 3000 RPM for the climb this should give 140 KIAS all the way to FL's without a problem, leaning from 5000ft to about 33% lean above 10,000ft.


3000 RPM 40-30 " MP will give 80-90% power
2750 RPM 32 " MP will give 75-60% power
2600 RPM will give 65-50% power.

So the desired fuel burn was the consideration, you always just accepted the speed that you got which was the outcome rather than aim for a specific speed for an power setting. Normal cruise would be 75% power lets say 180 KIAS and 65% power would be a economical cruise at about 170-150 KIAS, dependent on altitude. The trouble with this is that there is no one size fits all and it all depends on the OAT, Air pressure and air frame condition and of course weight, which sounds evasive but you generally worked out what were the desirable fuel burns and speeds that the operation demanded and flew them accordingly. Supercharging let you keep the power output at higher altitudes or at lower MP and RPM at lower altitudes. Effectively the fuel burn should be from 300 lbs per hour at max power coming back to normal lean operation of @150-140 lbs per hours, so you would flight plan on those figures. So that is what you aimed for, merely reducing MP and then RPM according to what you were after. In the RW economy was king unlike in the sim where it does not matter unless of course you get half way across the Atlantic and run out of fuel and prematurely end your flight.

I ran an altitude test on the model and this is what was the outcome. Using 40"and 3000 RPM there was no MP decrease until 10,000ft and 40"could be maintained until F140 with 3000 RPM at which point MP continued to decrease until it reached 30" at F210. The ROC of climb by this stage was down to 250 FPM. As there is no fuel flow gauge in this model I could not determine what the fuel flows were with any detail but in gross amounts they seemed ok. Those figures by the way are what I would expect from a supercharged engine. so I think they are ok.

I did note that I am inducing that flashing effect if I shut down a mag on the mag check which also generates smoke outside but it does dissappear not sure why or if there is a connection but it is strange. I do not get any real indication of a mag drop which is not a bad thing (brand new mags it would never be more than 50 RPM but as they wear that can increase) The dead cut on the switches works and the props cycle ok as well. I am using 20" and 2000 RPM on the runups.

I will give the new model a go. Other than that I really enjoy this one as well good stuff. I think I will have tinker with the views so I can ride up back now and then LOL.

Cheers

Mike