Blenheim take off

[JG53Frankyboy]

Originally Posted by meplay

Hi Seeker, the only thing i do is basically have my right engine throttle at 100% and left at around 50% and as my back wheel starts to come up i set the left engine to 100% also. The main thing that stops me from overheating though is when ive started to roll quit fast, i start to drop the prop pitch slowly till its about half way or lower and thats seem to be the only thing that stop my CHT from sky rocketing through the roof.

i just repeat myself, WHEN you warm up the engines to 200°C (NO joke!) , the engines work simultan when opening the throttles. No need to make on 50% and the other 100% than. It just take time to reach this temperature without speeding up the game...

CoD need a "warm engines" setting, RoF players know what i am talking about

[meplay]

Originally Posted by JG53Frankyboy

i just repeat myself, WHEN you warm up the engines to 200°C (NO joke!) , the engines work simultan when opening the throttles. No need to make on 50% and the other 100% than. It just take time to reach this temperature without speeding up the game...

CoD need a "warm engines" setting, RoF players know what i am talking about

yup i only put the left 1 at 50% throttle to stop it pulling off the runway to the right. then when i get rudder authority il (ie when tail is off ground) il set the left engine to full, i use prop pitch to stop CHT going above 250

I shoulda really said that ive already got my oil temp to 40 and my CHT to 200 by the time im ready for takeoff

[JG53Frankyboy]

you checked the ruddertrim ?
because as default it is full right IIRC.....

[meplay]

Originally Posted by JG53Frankyboy

you checked the ruddertrim ?
because as default it is full right IIRC.....

yeah i put it full left rudder at start of mission, still pulls over :/ i cant stop it unless i have my left engine to 50% and right to 100% throttle, even when i turn the cross wind to zero. on one of my own missions on the channel map.

[Sternjaeger II]

lol I don't remember where I was, but it was a little airshow and a girl was commenting on a turn on/warm up engine checklist that she spotted in a cockpit: she said something like "hey, get temperature to 200 degrees, it's like a recipe!" much to the amusement of the people around her hehehe

[Blackdog_kt]

Originally Posted by meplay

Hi Seeker, the only thing i do is basically have my right engine throttle at 100% and left at around 50% and as my back wheel starts to come up i set the left engine to 100% also. The main thing that stops me from overheating though is when ive started to roll quit fast, i start to drop the prop pitch slowly till its about half way or lower and thats seem to be the only thing that stop my CHT from sky rocketing through the roof.

Actually setting prop pitch to 50% has no effect. It uses two-stage props like the Spit.MkI but the sliders don't "snap" into the top and bottom position like they should. If you set pitch full back it goes to the low RPM position, if you set it at anything higher than that it's the same as running it full fine.

Which means that running with the slider at 50% has no real effect, you can take-off just fine with it at 100% and save yourself some trouble


As for the temperatures now, i too had a bit of trouble. I could take-off just fine with an accelerated warm-up if i'm not carrying bombs, i would advance the throttles in a series of steps with the brakes on in order to "force" a temp increase. When they are running rough the aircraft shakes, when the shaking stops you know it's sufficiently warmed up for the current boost setting so you push it up a notch or two.

However, i would only get the CHT (cylinder head temp) to 150 or so and upon trying to take-off with a bombload bad things would happen. If its unloaded you get enough acceleration and rudder authority even with the engines running slightly rough, but if it's loaded the acceleration is slower, airflow is less and engine components start to fail.

My most recent trick is frequent use of the cowl flaps to actively control CHT. This is also really critical during descent and approach/landing. You can't just chop the throttle and start descending at high speed, the engines will go cold and by the time you deploy gear and flaps and need the extra power for the flare and touchdown you don't get any.

In fact, the entire profile of the approach (how low can you set boost and how fast you can go in combination with your cowl flaps and prop pitch setting) is determined by keeping the temps where they need to be.

If you just put the nose down at coarse pitch (which will cause you to accelerate even further) and chop the throttle you're about to suffer.

Instead, chop the throttles first and go to fine pitch (high RPM), this combination makes the props windmill almost face-on to the incoming airflow and acts like an airbrake. Then start closing cowl flaps (i had them at about 30%-40% and it was still resulting in too low CHT), but remember to open them again when you re-apply throttle to settle into the glide slope.

Yes, it's difficult and the ergonomics in the cockpit are not really the best, but it's highly realistic. Similar things happen with most radial engines, you can take a look on youtube at the A2A P-47 for FSX, or even better, search for some videos showing DeHavilland Beaver aircraft in Canada or Alaska starting up their wasp junior engine.

Radials need some pretty intensive temp management, this workload is the trade-off for their reliability, power and combat resilience.

[JG53Frankyboy]

Online , and ONLY online:
are you able to change positions in a Blenheim without its engines are stopping?

Offline i have not this proplem!

[bob_baer]

Why the rpm doesn't modify changing the mixture? and also changing altitudes it doesn't seem the mixture change is needed. Is it a bug?

[Seeker]

Originally Posted by bob_baer

Why the rpm doesn't modify changing the mixture? and also changing altitudes it doesn't seem the mixture change is needed. Is it a bug?

Why do you think it should?

It's true that an incorrect mixture setting will have an effect on the RPM's achievable, but one wouldn't normally mess with the mixture to suit differing engine speeds.

[Blackdog_kt]

The mixture is semi-automatic: levers in the normal range (from the middle and back) is auto-rich, levers in the weak range (from the middle and forward) is auto-lean.

This is exactly like it worked in the real one too, the levers move all the way but they only have two effective functions: for example, if you have the mixture levers 30% forward it's the same as having them 10% of the way forward, both of it corresponds to auto-rich.


What i do is warm up by applying throttle with my cowl flaps closed and the carb heat on (it seems to accelerate the oil temp increase). Also, don't forget to set rudder trim full left and have the mixture levers back so that it runs on auto-rich.

As soon as my oil temps hit 35-40 and my cylinder temps are 200 i fully open the cowl flaps, hold the brakes and advance throttles to +2 lbs boost.
I do this to clear the engines and get them to a sufficient temperature so that i can then advance throttles even more without having them choke and run rough. I also turn off carb heat (it reduces available power) and wait a few seconds for the mixture to re-adjust and the engines to stop shaking.

At that point i enable the boost cut out (this gives you up to +9 lbs boost at the cost of overheat so you cant' use it for too long), advance both throttles to +4 lbs boost or so (throttles about 60-65% of the way forward) release the brakes, select the starboard engine and gradually advance it to more than +5 lbs boost.

Initially it turns strongly to the right, even under full left rudder and rudder trim, but you can straighten it out without using the brakes: just use short bursts of +9 lbs boost on the starboard engine. Don't leave it there as it will overheat and get damaged, just give it a burst or two to realign with the runway and then pull it back to +5 or so. Immediately pull it back if you get any shaking, this is your engine telling you it's about to blow a gasket but you can prevent it if you pull it back to +5.

During all this time the port engine is running steadily at +4 lbs boost or thereabouts.

By that time i'll be having some forward speed and planning ahead a little bit i will have turned a bit to the left of the centerline by means of throttling up the starboard engine, so that i have some time to react before it starts veering off to the right again.

At this point i select the port engine and gradually advance it to +5 lbs or more. I don't use +9 unless i'm doing what i described above to keep it straight, but i think it can easily take +7 or so (approximate value, as i'm not looking directly at the instruments while "dancing" on the engine controls). Throttle is roughly 90-95% of the way open at this point. The trick is to advance it gradually so that it can warm up (remember, we had the port one running lower boost to reduce the right turning tendency), just advance throttle in two stages to give it a couple of seconds to warm up during the process, instead of going full out at once and getting the "shakes".

This makes it want to turn right even more, but by this point i have enough forward speed to keep it pointing straight with the rudder.

At this point the hard part is over. I set both engines to +5 or a bit more, force the tail up with some down elevator and lift off at around 90-100mph.
I might give it a short burst of +9 lbs boost to get an initial breath of altitude while the gear retracts, then throttle back down to +5 and disable the boost cut-out (with the boost cut-out on maximum boost is +9, by disabling it maximum boost is +5).

I then set props to coarse pitch (pull the levers ALL the way back, anything above that corresponds to fine pitch) and trade that initial bit of altitude for speed, diving back down to get into the speed range where coarse pitch works well (at least 120mph).

From this point on i just monitor my temperatures and adjust cowl flaps as needed.

All flying apart from take off and landing is done with coarse pitch. Maximum cruising boost is +1.5 lbs for lean mixture (levers forward in the "weak" range) and +3.5lbs for rich mixture (levers back in the "normal" range). Maximum climb is +5 lbs for half an hour (i think it is half an hour, going from memory here), but when flying level +5 lbs is limited to mere minutes because the RPM gets too high. In other words, +5lbs in level flight is war emergency power.

All this is with four 250 lbs bombs and 60% fuel, which is more than enough to do a cross-channel raid from one of the airbases west of Dover to Calais and back.

The aircraft is a joy to fly once you get it up in the air (apart from the slightly annoying tendency to roll, you either fly with the rudder trimmed and have the roll to contend with, or you fly with improper rudder trim in a constant sideslip and get rid of the roll) and will easily cruise at 170-180 mph with zero to +1 boost, rich mixture cowl flaps mostly closed.

Comparing with a manual someone sent to me, there are a couple of things that need tuning in our in-game Blenheim.

First of all, all engines in the sim seem to be hard to overheat or even warm-up when idling on the ground, which seems a bit off for a situation where there's almost zero airflow. As for the Blenheim in particular, the manual recommends cowl flaps closed for takeoff because they provide enough airflow to keep the engines healthy as soon as some forward motion occurs. The in-game cowl flaps seem to be less forgiving than that.

So, the way it happens in the sim is that we warm-up with closed cowl flaps and open them for the takeoff, which seems to be the exact opposite of the real procedure: idle and warm-up with cowl flaps open because engines running while sitting on the ground overheat easily, then close the cowl flaps to accelerate faster as soon as the take off run starts and the airflow helps to keep them cool.

Second, the real Blenheim carries two kind of fuel. Start up, taxi, warm up and take off is done on the outboard tanks, cruise and return to base is done on the inboard ones. The sim correctly cycles the fuel cocks, the first time you click on them it selects outboard tanks and on the second click it selects inboard tanks, but i don't know if it models the different fuel.

What happened is that they added two extra fuel tanks to gain range, but the weight went up so they needed more boost for the take off. So, they modified the engines to run +9 lbs but this also needed 100 octane fuel. In the end, they decided to run 100 octane during take off from the outboard tanks and then run 87 octane during the rest of the flight from the inboard tanks. That's the reason for switching tanks after take off, once they throttled down.

I don't know if the sim models this, maybe this is why running +9 lbs in-game is only possible in short bursts.

Finally, the in-game flap controls are similar to the Spitfire (full up or full down), while in the real one they were more like the Hurricane: up, neutral, down.

In other words, in the real Blenheim it's possible to set partial flaps. Move the control to the "down" position to start lowering them, return it to the "neutral" position to stop them where they are.
The Blenheim manual in fact recommends 20 degrees of flaps when flying in long range profile (with the outboard tanks loaded).

Moreoever, the AI in the sim also uses partial flaps, but the way they do it is by rapidly cycling between the up and down commands (you can see this if you enable the autopilot and let it take off for you).

I've posted most of this stuf in another thread under the gameplay sub-section of the forums (http://forum.1cpublishing.eu/showthread.php?t=23192) and i hope to have the most relevant portions of the manual copied over soon.

In any case, i bet the Blenheim will get its share of fine-tuning in the upcoming FM/DM improvements that Luthier announced for the next patch.

Until then, use differential thrust with short full throttle bursts to keep it straight like i described above. It's a joy to fly once you manage to take off