fatherjack

Has a cure been found yet? Where is the "TwinProp_fat" that the errors refer to? Is it a plugin in an acf folder? Is the sim trying to load it? Maybe you should loose the KingAir350 for the time being.

I've had three machines up and die while x-planing. Cooked.

I'm on a four year old MacBook Pro and I get a bit better than that while flying an object heavy aircraft there. I did have a lot of trouble with Cormack's Dublin scenery but eventually traced that to a couple of bad 737 OpenScenery objects with double sided faces in the middle LOD. The symptom was an obvious drop off in performance while that LOD was active. I went away on contract unexpectedly soon after I fixed it and forgot about it. I never contacted the OpenScenery guys about it.

I had a couple of hours yesterday and did some flight testing. Method Reference data for these tests came from "Pilot's Flying Manual for Boeing B-17 Flying Fortress" ( available at http://depositfiles.com/files/rlud1sdr3 ). I tested five points on the Composite Crusing Control Chart (Appendix II, page 101). I have extracted that page, marked the test points and appended it to this post. I chose these tests because they would be easiest for me to execute, easiest to explain and easiest for others to replicate. All tests were conducted at or very slightly above 50,000 pounds and at 1013 hPa and 15ºc. For each test the aircraft was flown on autopilot (with one exception*) at the stated altitude and the power and RPM set. "Power" was the engine power number outputted by the x-plane "data see". It was set without respect to any of special engine controls; the power was set to the target value on screen. When power and RPM were established, the aircraft left to fly straight and level until speed stabilized. Weight was rechecked and the the aircraft left flying straight and level for another ten minutes. A screenshot was then taken. Weight was again rechecked. * The autopilot could not be set to hold 4000 feet at max emergency and this was flown manually. In each case the target speed was approached from a higher speed. This is established test flying procedure. Max Emergency speeds were achieved by descending at 500fpm to the target altitude at that power setting and then following the above procedure. In addition to the points marked on the graph I established the best lift/drag airspeed at 50,000lbs. This approximates the line marked on the chart "For long range cruising do not cruise at airspeeds below this line" (i.e. 150mph IAS for the real aircraft). In reality, 150mph IAS was the most important operating speed for the B-17 and most missions were flown at that speed. Results The raw data is presented in six attached screenshots. A summary of the test data is as follows: 24,000 feet Setting / IAS achieved / B-17 Documentation / Percentage of documented speed Max Emergency (1200hp @2500rpm) / 218.9mph / 204mph / 107% Max Continuous (1000hp @2300rpm) / 221.3mph / 192mph / 115% 65% Rated ( 650hp @ 1850rpm) / 200.4mph / 153mph / 131% 4,000 feet Max Emergency (1200hp @2500rpm) / 277.3mph / 238mph / 116% 45% Rated ( 450hp @ 1400rpm) / 197.1mph / 145mph / 136% Best lift over drag (about 400hp) / 176mph / 150mph / 117% Comment 1. The speed achieved for Max Continuous Power was greater than that for Max Emergency. 2. In no case was the result less than the documented speed in the Pilots Manual. 3. In every case the error was more than the 3% margin espoused by the aircraft's author. In two cases it was more than ten times this. 4. The error is greatest at lower power settings. Conclusions 1. The model has not enough drag allowing excessive speeds to be achieved at the specified power settings. 2. The model's best lift over drag is 26mph too fast, indicating that the model needs more parasite drag. 3. The model's propellor design is inefficient at high RPM, especially at high altitude. This compensates for the low drag and reduces the speed errors. Reason for edit: fixed typo.

That is no mystery but it is still causing problems (as are your brake priming controls). Indeed.

Yes, passable; good enough without being exceptional. But since you raise it, there are a number of minor to middling issues with it. 1. The engine locations are not correct. The outboard engines are too high with respect to the inboard ones. the outboard engines are actually not far enough outboard but that is visually insignificant. 2. The horizontal tailplane has dihedral which it should hot have. It is the wrong span too but that's not obvious. 3. The rear fuselage slopes up too much, making the fin a bit too short. 4. The mesh is not fine enough. Mesh density (within limits) has little impact on rendering performance and does not need to be scrimped on as much as many modelers think. 5. It's too shiny. A little thing but it shows up the coarse mesh too much. I have put 1200 hours (and more) into object models and I know well how much work is involved. My main criticism of the xpfr B-17 is of the aero design. The recent un-moderated personal attacks (and un-truths) illustrate the attitude of some of the authors to criticism. However since they have now invited me, here are my observations... 1. The fuselage has zero Cd. It needs this because the props are useless. Flying along with data showing you can see a L/D of 17 or 18 but you can still only manage 500 fpm at sea level. 2. The props have working angles from 89.9 to 90º and must be feathered to work, bypassing god knows what functionality in the sim. They are seriously oversized too. 3. The wings use the default NACA16 x-plane section. This is nothing like the required NACA 0018 to 0010 to spite the name similarities. They also only use two elements per mainplane, negating much of the clever programming by Austin. Multi-engined aircraft should use plenty of elements. Multi-element wings are necessary if you wish to see some of the normal aileron deficiencies at low speeds with a bit of slip. 4. Ailerons are massively oversized. 5. With no drag, this baby is not going to want to land, so they've added 60 square feet of flatplate area to the landing gear. At this stage I stopped trying to see what was wrong with it. It is a pity because, as I mentioned above, the cockpit is well executed and the exterior model is passable. One other problem area is the turbocharger control. In the real B-17, each engine has a mechanical supercharger capable of boosting the engine to 1200hp at low altitude without any extra puff from the turbos. Before takeoff the crew set full throttle and adjust the turbos so as the engines are at no more than 42" of mercury. This turbo setting is used until the critical altitude is reached. Above this, throttles are left fully open and turbo control is used to adjust power. This uses an innovative technique to access a dataref as a supplementary power control. A good idea and but not well enough executed, in my opinion, for a production release. The control effectively increases power without an increase in manifold pressure. Ultimately this may well prove to be very useful indeed as a fudge for non-plugin engine modeling. As a minimum, the manifold pressure gauges need an extra animation that factors in this new dataref. Without it, it is impossible to use it correctly.

Ah! That must be what I'm doing wrong. I swing right and move backwards. I'll have to start over from the start with priming the brakes. I did find that knob for that finally. I did see it before, but then stupidly skipped over that part. RTFM for this plan for sure! I cheated last night, set power and put the plane at 2,000 just to see how it flew. Seems to fly nice, but I think my power was all screwed up. Can I please get a type rating from the FAA after learning this sim? Tom Whereas the cockpit is well executed and the exterior model is passable, the acf of this B-17 is a disaster. I've had a look under the hood and it's a collection of misconceptions and interacting kludges. The aero in particular is useless. The attitude of the authors to problems with it is disappointing. The red letter RTFM notices would be bearable if the manual had anything useful to say. I have a B-17 Pilot's manual and it wouldn't help you either. The turbo controller which they are so proud of, is a mess. Even with the waste gates jammed open, the power available from the engines at sea level should not be less than 1200hp. Having said that, the B-17 was no wonder-plane and performance should be fairly woeful.