blue_six

Thank you Miro for letting us know. Our shared passion for flight modelling brought Kwiatek and I into contact many years ago, back in the days of BoBII. Once the initial language problems were overcome, I found his opinions and suggestions consistently insightful and invaluable. After we each moved on to different sims, it was always a pleasure to see his call sign popping up here and there, and I read his posts with great interest. His untimely passing in this tragic accident is a tremendous loss to family, friends and our flight sim community. Rest in peace, my friend. blue six

Try this one, Phil C6: https://forums.eagle.ru/showthread.php?t=169358&page=38 Page 38 of the MB-339 discussion in Mods & Apps \ Mods blue six

I prefer the one increment nose up setting shown in the original post and described by Capt Orso for takeoff, for the simple reason that it better sets the aircraft up for climb out. "Neutral" or one division nose down on the gauge requires the model to be coaxed into the air, followed by conscious and sustained back pressure and rapid re-trimming, to maintain a nose up attitude. I appreciate that the one division nose up setting runs contrary to the Pilot's Notes and our various guides - the most expedient solution to bring it all together would be to recalibrate the gauge, making the current one degree nose up appear as neutral.

Thanks for clarifying that, Yo-Yo. I can only conclude from this that I'm actually getting better at flying this outstanding module (in my mind, at least). blue six

Agree, rudder effectiveness doesn't seem to be fading with increased q to near the same degree as the other two primary flight controls. Control harmony suffers as a result. Looking on the bright side, it seems to me that the Spit is noticeably easier to taxi - it's not quite so eager to diverge from the desired path as soon as your attention wanders, and often can be brought back into line with just a short dab of rudder. I'm finding crosswind takeoffs and landings are less of a challenge, and takeoff itself seems smoother overall than at 1.5.7. Trimming for straight and level flight is quick and easy, and once done it seems to hold the intended attitude more effectively, giving more time for fiddly head down tasks like setting a compass heading. blue six P.S. I wonder how much of this is just in my imagination? Wouldn't it be nice to know exactly what they've done?

What Art-J is saying, TC, is that when your right wing has dropped and your left wheel is off the ground, you need to apply right rudder and brake, to bring things back to an even keel. Try it, it works, just don't overdo it.

General interest item. The accompanying video clip runs approx. seven mins. Take the time to explore the two links at the bottom of the article, on the life and death of Arnold Roseland - you won't be disappointed. http://www.vintagewings.ca/VintageNews/Stories/tabid/116/articleType/ArticleView/articleId/593/The-First-Flight-of-the-Roseland-Spitfire-IX.aspx blue six

I'm with zero and bernp on this one. The pointer on the airspeed indicator is overly difficult to see at a glance, unless you are zoomed in to an unrealistic level. blue six

For what it's worth, the Flight Operating Instructions and Pilot Training Manuals for the P-51D impose a limit of 10 seconds for inverted flight "because of loss of oil pressure and failure of the scavenge pumps to operate in an inverted position." The engines involved are the Packard Merlin V1650-3 and V-1650-7. Near as I can see, these are basically equivalent to the Merlin 61 and Merlin 66 respectively. I am inclined to support the OP's contention that it is unrealistic for our Spit to fly inverted for such prolonged durations, with no drop in oil pressure and no resulting engine damage. blue six

Per the initial post by Holbeach, fuel starvation eventually stops the engine. In the video clip he's attached to his post, the low fuel pressure warning light comes on and the engine begins cutting out at approx. 1:25. Temps and pressures look to remain OK, and he reports no apparent engine damage as a consequence of this prolonged time in inverted flight.

Thanks for confirming that, Holbeach. Hopefully the devs plan to implement this in the future.

I don't know, Sokol1_br, and hadn't even considered this possibility. I am more likely to forget to move the lever to "normal" after takeoff than to move it to "filter in operation" prior to landing. And unless the dust damage during and after landing was immediate and serious, or was modeled to persist and accumulate over several sorties, it seems unlikely to be an issue for me at least - at this stage, my poor Spitty seldom survives more than three or four trips before being written off in a landing accident...

I understand, thank you. The point I am making is that if the filter is mistakenly left on, there should be a performance penalty due to the associated restriction on the intake. I don't see this modeled in the sim, and think it should be. Just as hypoxia is modeled when you forget to turn on your oxygen, there should be consequences to this pilot error.

The RW Spit MkIX Pilot's Notes have a note in the "Climbing" section cautioning that leaving the air intake filter control in the filter in operation (forward) position reduces the full throttle height considerably. I'm not seeing any performance penalty from failing to move the lever to the normal (aft) position after takeoff, either in full throttle height or in straight and level max airspeed. Can anyone else confirm? I'd expect to see this modeled, eventually - perhaps we're just not there yet?

Here's a link to the info provided by Yo-Yo, as discussed by MAD-MM: https://forums.eagle.ru/showthread.php?t=163126&highlight=spitfire+top+speed

Believe you're right, BodyOrgan. Last time I tried it, death came suddenly and without warning. One second I was chugging merrily along, looking at the altimeter and marveling at my ability to get along without oxygen. A second later, snap to external view, dead as a doornail.

Agree, saw the same thing here. Left the fuel cock OFF, switched on the electric boost pump right after moving the mixture lever forward to the run position, and got a good start. Idled for 2-3 mins, switched the boost pump OFF and the engine still continued to run. Something strange going on here, it seems.

Thanks for all your work on this Friedrich-4/B, my curiousity is well satisfied. To celebrate, I repeated my earlier trial in the Free Flight IA mission, this time leaving the boost pump ON. No problems at all, clawed my way up to 41,000 w/o a hiccup, even w/o switching on the fuel tank pressurization. The DCS Flight Manual and Quick Start guide could each benefit from some attention in this area. The fuel system description makes no mention of the electric boost pump at all, nor does it appear in the various checklists for start-up, warm-up, climb and landing. It's ON by default in all the IA missions which begin with the engine already running, so clearly someone appreciates its importance.

I did a couple of quick trials last night, just using the Free Flight IA mission. Start conditions for this are 6500 feet altitude, 3000 rpm, fuel tank pressurization OFF and boost pump ON. In both cases I immediately switched the boost pump OFF, set boost to 12 psi, reduced rpm to 2850 and commenced climb at 180 mph. While climbing I adjusted throttle and climb angle as needed to keep boost at 12 psi and maintain 180 mph for as long as possible. No problems were seen with overheating, and overall, the results were not quite as bad as expected. First attempt, reached approx. 16,500 feet before the engine began to run roughly. The low fuel pressure light was not illuminated. Leveled off and switched fuel tank pressurization ON. Engine began to run smoothly again within 30-45 seconds. Resumed climb. At approx. 37,000 feet low fuel pressure light came on and engine cut out entirely. Lowered the nose and attempted restart. No success, all the way down to 10,000 feet, at which point I switched the boost pump ON and the engine immediately roared back to life. Called it a day and went to the Mess for a beer. Second attempt, switched fuel tank pressurization ON at the start of the climb. No problem seen until approx. 38,000 feet, at which point the low fuel pressure light came on and the engine died. Switched the boost pump ON and the engine immediately came back to life. Resumed climb, eventually coaxing it up to 41,000 feet, very briefly. Even flying straight and level is a challenge up there. Thought I deserved another virtual beer after that. I'm left questioning a couple of things concerning the initial engine problem at approx. 16,500 feet (first attempt, with tank pressurization and boost pump both OFF). First, why no low fuel pressure light? Second, is it realistic that we not even get to 20,000 feet w/o fuel delivery problems? If anyone out there has the time and inclination, it would be good to get confirmation that what I saw is repeatable.

Good finds, Friedrich-4/B; thanks for sharing this info and putting my mind at ease. I'll treat those 1946 Pilot's Notes with just a bit less respect from now on, and get on with exploring other features of this outstanding module.

Agree, not a good example, nor is the schematic you've linked us to entirely clear. My money is on the priming line running around not through the boost pump, given the way the two segments line up perfectly on either side of the pump. This isn't a biggie, either way. What we still don't know for certain is why we can't obtain a good engine start in the sim when we move the idle cut-off control forward prior to priming and hitting the start and booster coil buttons, per the sequence set out in the RAF Pilot's Notes. Is it an inherent limitation of the sim, or a bug that can be squashed?

Thanks Holbeach, but I'm still unconvinced. The main features distinguishing the variants of the Spitfire IX, XI and XVI are outlined in Part I (Descriptive) para 1 of the RL manual. It stipulates that the while the F IX had a Merlin 61, 63 or 63A engine, the LF IX had the Merlin 66 engine. It goes on to note that "Merlin 61 and 63 engines have S.U. float-type carburetors, but on Merlin 66, 70 and 266 engines these are replaced by Bendix-Stromberg injection carburetors." Figure 4 (Fuel System Diagram) at the back of the RL manual illustrates two configurations for the Merlin 66 and 70 engines, one with just the wobble pump (described as "early Merlin 66 and 70 engines") and one with only the electric boost pump (later 66 and 70). Our DCS version falls between these and has both pumps. A note at the foot of the drawing advises that Merlin 61 and 63 engines are not fitted with boost or wobble pumps. Based on all this and the earlier investigation of wobble vs boost pump, I'm inclined to conclude that: a. all LF IX had the Merlin 66 engine; b. all Merlin 66 engines had the Bendix-Stromberg carburetors; c. early LF IX had the wobble pump only, "transitional" LF IX had both wobble and electric boost pumps, later LF IX had the boost pump only; d. it is very unlikely that the early LF IX (which had no boost pump) would be altitude restricted in the way our DCS model currently is, when the electric boost pump is not switched ON (I can't picture the RW pilot frantically working the wobble pump in order to climb to altitude); and e. therefore, we have a bug. The engine should not be suffering fuel starvation at altitude just because the electric boost pump has mistakenly been left OFF.

We've established in another thread https://forums.eagle.ru/showthread.php?t=179160 that early Merlin 66-engined Mk IXs had no electric fuel boost pumps, just a wobble pump. Slightly later Mk IXs had both, and eventually the wobble pump was dropped in favour of just the boost pump. If we accept that having the boost pump switched ON is necessary in the sim to get to higher altitudes , this begs the question how did the early Mk IXs manage it, without this mod? Or did they? Can anyone shed any light on this? I don't think we can discount the possibility that what we're seeing here is a bug.

The impression I get from examining the fuel system schematic in the RAF Pilot's Notes for the Spitfire IX, XI and XVI is that the priming pump has its own "plumbing" to the engine, independent of the primary fuel line which runs from the lower main tank, through the fuel cock, fuel filter and engine-driven fuel pump to the carburetor. As such the primer pump circuitry is not pressurized by the wobble pump and/or electric boost pump. The Pilot's Notes for the Mk IIA and B show this more clearly, with fuel for the priming pump being tapped from the side of the lower main tank, and pushed by the priming pump along a line terminating in the words "to cylinders." In contrast, the main fuel line in this older schematic is marked "to carburetor" just as we see in the Mk IX Notes.

Thanks for this Sokol1_br, but blimey, don't you have something else you should be doing on Christmas morning? And for that matter, why am I here too? Blue six out.