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#81
08-17-2011, 07:53 AM
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Seems that 50-60% throttle is what most of you use for successfully take off without overheating.
Gonna try that tonite. xpupx, good tip on using pitch to keep CHT within margins while taxing. Will try that. 
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#82
08-17-2011, 08:03 AM
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You have only tow pitchsettings, coarse and fine. Just move your pitchcontrol from 100 to 0% when the engines are still off and watch the propellerblades......
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#83
08-17-2011, 02:41 PM
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That's what i initially found out and it's confirmed by the manual for the real aircraft, the Mk.IV had a propeller system similar to the DH hurricane and the early Mk.I Spit we have in the sim with only fine and coarse positions. In the sim however it's possible to move the pitch sliders gradually but only the fully back position switches to coarse and anything above that switches to fine.
On the other hand some people say that while the animation is that of a two-stage prop, it actually works like a fully variable one. I think we need to do some more testing to clarify this. Xpupx's write up is still good advice though, minus a small inaccuracy: there is no water temp on Blenheim. The engines are air cooled so the gauges display cylinder head temperature  Other than that it's pretty sound advice, especially the part about how each engine control affects certain parameters. I still do some things differently but it doesn't mean it's the only way. For example i don't keep the carb heaters on unless i'm flying close to clouds, because heating the air lowers its density. This means that the mixture is also altered (less air volume for a given fuel volume, it's like running a richer mixture) and i don't know if the semi-automatic mixture systems corrects that. What i've found out is that you can easily fly up to 10000ft without any carb heat at all. I just turn it on along with the pitot heater when i get fog/icing on my windshield, then turn it off once i'm out of the layer of humidity. Now, i don't know how close this is to reality, but the current Blenheim in the sim can fly fine with reduced or no carb-heat usage when in clear skies, getting a bit more performance in exchange for having to keep an eye out for potential icing effects. It's easier to just set carb heat at a certain alt and leave it there but you'll get a bit reduced performance, so it's up to us to individually decide on how to do it. However, in the real one they probably left the carb heaters on so i guess i should start doing it like xpupx does  The mk.IV manual has no recommended settings about carb heat, but the Mk.V manual does. Since the engines are the same (the main difference is that the Mk.V has constant speed props while the Mk.IV has two-pitch props), maybe we can follow the same guidelines. Here's what it says: 1) Warm intake should be used: a) For all flying at less than +3.5 psi boost, unless atmospheric temperature is more than +15 degrees Celsius. In that case (more than +15 C), Cold intake should be used regardless of boost. b) For all flying (regardless of boost used and ambient temperatures), when in conditions of high humidity, in or just below clouds, in rain, snow or sleet. Warm intake can also be used to help warm-up the engines in very cold weather. 2) Cold intake should be used for all other conditions, including: a) Starting at all times b) Take-off c) Landing, unless the bad weather conditions of 1b) apply. So, i guess it's safe to turn it on and keep it there at the altitude where the ambient temp drops below 15 C. Since we don't yet have the dynamic weather, i guess the sim uses a standard atmosphere model. In that model, the ambient temp on sea level is considered to be 15 C and drops 6.5C for every 1km of altitude (or roughly 3000ft). In other words, if CoD uses an ISA atmosphere and the carb heaters on our Blenheim are similar to the Mk.V carb heaters, we can turn on carb heat as soon as we have completed takeoff, assuming we climb at less than +3.5psi boost. I usually set it to +1 boost for a normal cruise climb, so it would definitely apply to my method. The easiest way to see what kind of ambient temps the game uses is to spawn a Blenheim in the cross country mission in the QMB without starting the engines, accelerate time for a while to let the engines and oil get up to ambient temperature and see what kind of temps the instruments indicate. I think that last time i checked this CHT temps were 10-12 C, so it definitely looks safe to turn on carb heat as soon as you climb 500-1000ft after take-off and settle into reduced power settings.
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#84
08-17-2011, 04:03 PM
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On atmosphere model - if there's a landing strip on a higher alt then one could check ambient temps at sea level then fly (or fix it in FMB) to the strip at higher alt and let the engine cool down.
 Then we'd see if there's a change in temps at diff alt at all. I could do that but I dunno where to check for alt (I never set that on the alt meter). Btw, anyone checked if temps changes over the course of the day? That should be simple. Gonna check right now actually. Brb. Ok, back now. Ran for almost an hour. In game time (tod) was from 09.00 to 23.00. I checked Oil temp and CHT. No change what so ever at anytime during the test. A bit funny is that all temps showed different - oiltemp port 17, oiltemp starbord 14, CHT port 10 and CHT starbord 12. I see this as an indication that there's no atmosphere model at all except for clouds. Last edited by Vengeanze; 08-17-2011 at 05:13 PM.
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#85
08-17-2011, 09:23 PM
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Tried with 60% throttle now and that did the trick for me.
Not much runway left but who cares. It's fun handling the Blenheim but when I read about it on Wikipedia it is depressing how little damage they did and the high number of casualties they sustained.
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#86
08-17-2011, 09:48 PM
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Quote:
Prop pitch seems to be two stage in the 3D modell. (on 0 pitch input it turns right to a more featherd position, on anything else than 0 it turns left to its takeoff position. You can observe it when the engines are stoped) However, it have a full effect on rpm in different positions (not just two stages) as I measured: Throttle 75 % IAS 200-210 mhp Height 8000ft Radiator 100% Carburetor heat 100% Pitch % / RPM 100 / 2660 75 / 2520 50 / 2320 25 / 2120 0 / 1760 My findings about the carburetor heat Carburetor heat seems to work inversely. In 100% you'll get less engine temperature then in 0% Throttle 50 % Pitch 75% IAS: 150-160 mph Height: 8000 ft Radiator 100 % Carburetor heat % / Engine temperature °C / RPM 100 / 201 / 2260 75 / 203 / 2290 50 / 208 / 2340 25 / 221 / 2380 0 / 233 / 2480 Also the carburetor heat controll lever labeld as "AIR INTAKE SHUTTER" (Don't really know how it suppose to work on this airplane) Also mixture doesen't work at all. Just try a mission with mixture at 0%, then refly the same mission with 100% an you won't notice any difference at all, regardless the altitude. Last edited by Mechanist; 08-17-2011 at 10:02 PM.
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#87
08-17-2011, 10:14 PM
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Interesting findings, maybe we can use a bit reduced pitch to prevent overheating then until they correct the propellers and the airflow/overheat modeling.
As for the mixture, it's semi-automatic (just like in the Spitfire) and that's why we can't see a difference: 0%-50% mixture is auto-rich, 51%-100% mixture is auto-lean. It will automatically maintain either of the two ratios depending on where it's set at, so moving it back and forth doesn't produce any rough running of the engines. I know you will wonder why does the lever move gradually, instead of "snapping" into the two extreme positions like in the Spitfire, but for some weird reason it was like this in the real aircraft: full range of motion for the levers but only two effective settings.
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#89
08-18-2011, 08:03 AM
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Carbheat works fine for me. Has anyone climbed over 11k ft without engine shake? 56RAF_phoenix
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#90
08-18-2011, 08:15 AM
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Quote:
56RAF_phoenix
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Linear Mode
