Blenheim Mk IV start up ?

[meplay]

Originally Posted by Dutch_851

Maybe they built the field on the side of a hill?!

Me, I gave up and allowed the plane to turn into the wind and took off that way, just missing a couple of houses in the village down the hill.

Very hairy experience!

But it was to no avail, the starboard engine gave up the ghost after only a few miles.

Nor did I succed in a previous attempt to taxi to the other end of the runway and turn around.
The engines gave up before I could get there. This was after going to the shops and making a cup of tea whilst the engines warmed up, but they still hadn't got above 40 degrees oil temp and midpoint on the CHT.

I've also tried different throttle settings for each engine, different prop pitch for each engine, but nope, engine failures every time.

As an aside though, what is the necessity for carb heat?
I thought this was only used to prevent carb icing at altitude, or in very cold weather.

A little trick i do (i dont have a quadrant or duel throttle) is when i rev up to 100% with both engines then quickly select engine 1 then drop that to about 50% throttle then select both quickly and put the prop pith down to about a third (seem to cool it, im already rolling at this point) then push forward while keeping straight until the tail comes up then select engine 1 and send it to full throttle, then select both again for the flight out!

I think you've deff gotta get the oil temp above 40 though cos it feel rough and over revs if you havent :/

[ATAG_Dutch]

Originally Posted by meplay

A little trick i do (i dont have a quadrant or duel throttle) is when i rev up to 100% with both engines then quickly select engine 1 then drop that to about 50% throttle then select both quickly and put the prop pith down to about a third (seem to cool it, im already rolling at this point) then push forward while keeping straight until the tail comes up then select engine 1 and send it to full throttle, then select both again for the flight out!

I think you've deff gotta get the oil temp above 40 though cos it feel rough and over revs if you havent :/

Yeah, that's one of the many things I've tried apart from coarsening pitch on the the roll.
I noticed on simple engine management that temps were about 50, so will try warming up to that and using your pitch technique.
If it works, I'll owe you a pint!

[Blackdog_kt]

The most common source of failure (especially if using differential thrust with the starboard engine running flat-out) is the prop governors.

I don't know how realistic the entire situation is with that mission, but what i do know is that the governors will fail on a real aircraft if the oil is cold and high power is used (as long as it's an oil-fed governor system), because oil viscosity is higher at low temps (ie, it's thicker), this increases the pressure and things start to break.

Now that i mention it, it reminds me of another little trick to try that's part of many real-world checklists. Even if the oil in the engine is warmed up, the oil in the governor might not be.
To ensure smooth running in aircraft that use oil-fed governors it's not unusual to do the so called exercising of the prop: once the engines warm up a bit to be able to generate some power without mis-firing, take it to a moderately high power setting to further help with warming-up (i'd say stepping on the brakes and using 0 boost or so would do it), then move the prop pitch levers back until you get a noticeable RPM drop (depends on the type of engine/aircraft, general aviation aircraft usually advise a 300-500 RPM drop), then forward again.

If 0 boost doesn't make the RPM needles budge, use a higher setting until you can get them to register some indication but not too high to cause problems. That's part of the reason that real-world checklists specify RPM limits for the run-up procedure. It is implied that pitch is at full fine but due to the low power the RPM is not increasing, then the pilot increases throttle until a certain RPM is reached and exercises the props to the specified RPM drop value.

What this does is command a pitch change from the governor which works by regulating oil pressure inside it. So, if you repeat this 2-3 times it has the effect of "recycling" the cold oil in the governor back into the engine where it's warmed, then back into the governor.

I haven't tested this yet (just thought of it) but i'll be pretty amazed if they modeled it.