Blenheim operating limits and checklists

[bando]

Originally Posted by JG53Frankyboy

how do you lock the brake ?

Well, I'm using quite some throttle sticks. The CH quadrant has 6 levers and the one from Saitec has three. So the lever on the joystick (MSFFB2) is used as the braking lever. As I shove the thing forward and leave it there, my brake is essentially on.

When I need to brake slow, this lever helps as well. For the amount of "breaking power" is equal to the amount of "travel" on the lever. Hope it makes sense.

[JG53Frankyboy]

ah, ok, you have the brake on a slider/axis.

Something to think about, i also use the MSFFB2 (with X52PRO Throttle) and the MSFFB throttle is in no use in the moment....

[klem]

Originally Posted by Blackdog_kt

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Important: Interestingly enough, since +9lbs is only to be used for takeoff when the outboard tanks are full, only these outboard tanks carry 100 octane fuel
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Are you sure BD?

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http://en.wikipedia.org/wiki/Aircraf...tle_of_Britain
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100 octane aviation fuel

As early as 1938 Roy Fedden, who designed most of the Bristol Engine Company's most successful aero engines, pressed for the introduction of 100 octane aviation spirit from the USA.[23] During 1938 the British aero engine manufacturers Bristol and Rolls-Royce demonstrated variants of their 'Mercury' and 'Merlin' engines rated for 100 octane fuel[24][25]
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Notes

1. ^ In September 1939 Bristol Blenheim Mk IVs of several squadrons of Bomber Command (18, 21, 57, 82, 90, 101, 107, 110, 114 and 139 Squadrons) were being converted to use Bristol Mercury XVs and to carry additional fuel tanks for 100 octane fuel in their outer wings. This work was completed by 7 October.[29]

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and

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http://en.wikipedia.org/wiki/Bristol_Mercury
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Mercury XV
(193 825 hp, developed from Mercury VIII. Converted to run on 100 Octane fuel (previously 87 Octane).
============================


Could it have run on 87 as well?

[Blackdog_kt]

Well, it's in your own quote

Originally Posted by klem

1. ^ In September 1939 Bristol Blenheim Mk IVs of several squadrons of Bomber Command (18, 21, 57, 82, 90, 101, 107, 110, 114 and 139 Squadrons) were being converted to use Bristol Mercury XVs and to carry additional fuel tanks for 100 octane fuel in their outer wings. This work was completed by 7 October.[29]

The way it reads to me is the outboard tanks were filled with 100 octane. I'm looking at the Mk.IV manual as we speak and the way it goes is something like this:

1) We need more range
2) We add two more fuel tanks
3) Plane is now heavier so we need more power
4) Modify the engines to run higher boost
5) Higher boost needs better fuel
6) Fill the outboard tanks with 100 octane
7) Use outboard tanks for takeoff and emergency power
8 ) Use inboard tanks during cruise because the power settings are lower and there's less risk of detonation

I'm not an engineer mind you, just going by what the manual says. Everything in the manual points to the fact that the engines could switch between 87 and 100 octane mid-flight without problems, as long as the correct boost limits for each fuel type were observed to prevent detonation.

As for the rest of the checklists, sorry for the delays but i've had a bit of a busy week. I don't want to just copy things over, so i'm taking the time to format it in an easy to read manner.

The manual mentions a lot of stuff in detail and then provides abbreviated limitations, or gives additional information in a different section. What i'm trying to do is fuse that information together in a way that's easy to read and follow.

The end result is shortened checklists that contain only the stuff applicable to the game for all relevant systems. For example, i make no mention of hydraulic pump operation because even though it's modeled in the sim, its operation is automatic.
I do this separately for every phase of flight (start up, warm up, taxi, take off, cruise, etc), so it needs quite a bit of back and forth though the pages.

As you can guess it's taking some time, but i might be able to have it done and posted during the weekend.

[klem]

Thanks BlackDog.

I tried the Blenheim the other night and it was just a pain to get off the ground, especially not knowing why (like using the outer 100 octane fuel tanks). Also need to know those max boosts for each. Some of our guys want to try it although I'm not mad on the idea

Look forward to more of your info.

[Blackdog_kt]

Well, just to get you started:

Takeoff at full fine pitch. I don't know if the sim models the different fuel in the outboard tanks. The real life drill is to select outboard tanks, set the boost cut-out to on and give it +9 lbs boost while doing what is by now common knowledge to keep it from veering to the right (brake and left rudder to force left wheel braking, more throttle on the starboard engine and less on the port one), until you get sufficient speed that your rudder becomes effective.

In one of Freycinet's videos you can also see a different method. He only gives it about 60% throttle which lessens the drifting to the right, until the airspeed rises and the rudder is again effective.

Then you can advance both throttles to full, lay off the brakes and keep it going straight with the rudder.

Lift off at about 80-100mph but don't climb. Retract gear and disable the boost cut out (which lowers your maximum boost to +5 lbs) to keep your engines healthy.
Once you reach 120mph go to coarse pitch (pull the pitch levers all the way back, anything above that qualifies as fine pitch so if you just set it to 50% of the way you're still running full fine and high RPM).

Once you reach 150mph you can start climbing. Max climb is +5 lbs and about 2600-2700 RPM (going from memory here) but i don't know how the in-game CEM agrees with that. In any case, even the manual recommends climbing at lower settings for economy reasons so it should be perfectly possible.

Max continuous is +1.5 lbs for lean mixture and +3.5 (if i'm not mistaken) for rich mixture. Once again, mixture is either auto lean or auto rich, there are no in-betweens. In this case however the full-range motion of the levers is historically correct, you just set them according to the demarcation labels on the throttle quadrant. Lean is with the levers forward and rich is with the levers back.

To cut a long story short, as soon as you lift off raise your gear, level out, go to coarse pitch once you hit 120mph, disable the boost cut-out and throttle back to +3.5 lbs boost. When you hit 150 mph trim it for climb, start monitoring your engine temps (you might need to close the cowl flaps a bit, this will also give you some more speed and a better climb) and give yourself a pat on the back.

You might also want to switch to the inboard tanks once you're established in the climb, just to start learning good habits for when the different fuel is modeled (if it's not already). Another reason for this is that only the outboard tanks have the ability to jettison fuel (again, i haven't tested if this is modeled in the sim), so it makes sense to first burn the fuel you can't dump in an emergency during cruise to maximize on saving weight in such a case.

Once you reach your chosen cruising altitude and trim for level flight, throttle back to +1.5 lbs boost and set mixture to auto lean (levers full forward) to maximize your fuel economy.

[klem]

Don't know if this will help or not but I'm attaching some info I got from reading the Blenheim MkV pilot's notes. Ours is the MkIV but the engine is the same (Mercury XV)

[JG53Frankyboy]

in my experience so far, i dont use coarse pitch at all. I dont get enough rpm to keep the engine at needed temperature with coarse
I fly only fine pitch, and reduce throttle to keep rpm and temperature in the games desired limits...

[klem]

In case you were still wondering I got a reply from the Blenheim Society on the two fuels in the Blenheim:

...... has passed me your query re fuel of different octane ratings used in the Blenheim IVs. Yes they did have two different fuels in the same aircraft!
100 octane in one pair of tanks used for take-off and emergencies with a 'Plus 9 lbs boost' lever, and a lower octane fuel for far less boost pressure, used for cruising, in another pair, and of course this did lead to many accidents, often fatal.
How this came about is explained in detail in my book "The Bristol Blenheim - a complete history" published by Crecy. You can buy one at the discounted price of under £30 for Blenheim Society members from Ron Scot the Society Hon. Treasurer on 01 992 442 608 or borrow one from a public library.
Seems to me one or more of your group could join the Society at £15pa as they publish an excellent Journal, and have an annual Blenheim Day and lunch at Duxford with access to the actual aircraft and opportunity to meet the few remaining wartime crew and the present day engineers.
Regards Graham Warner

Enthusiasts may like to buy his book and even join their society

[335th_GRAthos]

Excellent information, impressive detail.

Now, coming back to reality, why can I not start the frigging engine?

fuel cocks (the round things on the right) on
magnetos on
throttle @20%
carb heater on (off did not make a difference either)
mixture middle
select engine #0
press I to start
It turns and dies


~S~