Blackbird Sims / Milviz Forum Archive

I have a strange problem with the Bobcat. So far it seems to only happen when I get to higher altitudes where things such as mixture and temperature management play a more more significant role, but despite that obvious place to look for answers, I cannot resolve the issue.

Basically what happens is that despite all gauges remaining in the correct zones, the power simply ebbs away - almost completely - after perhaps 20 minutes or so. The throttles still move in response to control input however the power output from the engines just falls completely away - the best I have seen is around 17 inches. Often it is much worse than that and I basically only have idle power.

But I cannot work out what I am doing wrong. I am maintaining mixture correctly, carb and oil temps correctly, running at acceptable prop rpm and cruise settings. Yet this same problem occurs no matter what. I don't know if it is coincidence of not but I have not seen it happen when hopping between airfields but in cases like that I would barely ever get above a few thousand AGL and the flights are generally short. Again, coincidentally or not this issue only seems to happen at higher altitudes which as mentioned would immediately rouse suspicion in relation to temperate management - but again I cannot see what I might be doing wrong. All the needles are pointing in the right places.

The only "fix" seems to be to completely turn off the bank of four magnetos (on the lower right hand side of the instrument panel) and the master switch for a handful of seconds then turn them all back on and then re-start the engines. Though sometimes this will only work if I do an emergency landing first. That made me suspect something electrical but again there is only so much electrical stuff in this aircraft - and things like the generator switches etc, for example, don't seem to have anything to do with the problem.

I can only think I am missing something obvious here or there is some sort of obscure bug in my setup or FSX Steam causing this issue, since it is completely unique to this aircraft (and I have three other Milviz and several other third party where I have never encountered this issue before).

Nevermind. How embarrassing. It was icing!! Sorry to waste your time. My guess is maybe props and / or intake since I was always making sure all temps on the gauges were in the correct zones. And actually the sound did slightly change when this was happening - though not simply the same as closing the throttle.

That would have been my first guess or an errant weather program.

Thanks for the reply Steve and again sorry I did not bother to even check this first. As for the weather program, it is actually my own - I wrote it so I could get infinitely varying weather from flight to flight day to day even when simming totally offline in the "old" FSX (which I only ever use offline). But it is based on the weather theme SDK and when it comes to cloud icing, the "choices" are somewhat granular. You get no icing_none, icing_trace, icing_light, icing_moderate and icing_severe. Although I was at pains to have my weather generator use real world theoretical calculations, in the end when it has to create the theme it has to decide at that level of granuality. Same for turbulence, precipitation, etc. But even so, I am incredibly impressed by the way even good old FSX simulates weather.

So anyway after much thought and not wanting to be limited in the sim like I might be in the real world (grounded due to weather) I have just added a "cheat" checkbox on the interface screen to eliminate all icing regardless of whether it should theoretically exist or not. And if I want to be really serious I can just leave the checkbox unchecked and avoid clouds and keep to lower altititudes on days where icing might be occuring higher up if I am flying an aircraft such as the Bobcat.

I've being testing the changes for two days now and have had zero issues, so the "fix" works perfectly though it is not realistic. So I will pay more attention to the way I fly the Bobcat in future!

But I have to commend the modelling here since I am sure it was not my imagination the sound even changed when it happened. Almost like the engine was being over-worked (which I suppose is one symptom of prop icing amongst others).

I have never come across the issue before though - mainly because all aircraft I have flown apart from this Bobcat are perfectly capable of IFR flight and did not really have any extensive modelling of potential failures like these high end payware aircraft have.

Anyway, this has given me even more appreciation for what is now a 15 year old simulation - and an appreciation of why (here in Australia at least), they strongly advise to turn back to your departure airfield if you run into unexpected cloud formations and you are flying an aircraft ill equipped to fly through IMC and / or you are not licenced to do so.