Hurricane mixture

[bob_baer]

Hi guys I know it's already been discussed but I'm confused. In the hurricane how does it work the mixture? Is it true that it's linked to throttle position?
Thanks
Ciao

[Vengeanze]

At work now but isn't it the Spit that has the mix connected to the throttle?
It's mechanical meaning that there's a spring on the throttle leveler that physically pushes the mix leveler back to weak mix when you throttle down.

The hurri is independent of the throttle.

Or if it's the other way around.

[Blackdog_kt]

The hurricane's throttle handle has a knob that extends to the side, which pulls back the mixture lever when throttling back. This is also why the mixture is reversed and rich is backwards: the aim is to have the mixture go to rich when throttling back to prevent running rough at low throttle settings.

It's similar in the Tiger Moth with its manual mixture and in order to maintain similar controls among all RAF aircraft and not confuse the pilots when converting from one type to another all RAF aircraft, even those with semi-automatic (auto-rich and auto-lean) mixture controls, follow the same reversed system.

[Vengeanze]

Originally Posted by Blackdog_kt

The hurricane's throttle handle has a knob that extends to the side, which pulls back the mixture lever when throttling back. This is also why the mixture is reversed and rich is backwards: the aim is to have the mixture go to rich when throttling back to prevent running rough at low throttle settings.

It's similar in the Tiger Moth with its manual mixture and in order to maintain similar controls among all RAF aircraft and not confuse the pilots when converting from one type to another all RAF aircraft, even those with semi-automatic (auto-rich and auto-lean) mixture controls, follow the same reversed system.

That's what I said...but in different words.

[bob_baer]

Thanks guys, isn't the hurricane mixture semiautomatic? And why it's needed to enrich the mixture throttleing back and not leaning it increasing throttle? Making some tries it seems that increasing throttle keeping rich the mixture is giving too less power (also at sea level during take off)
Does anybody know how semiautomatic mixture works?
thanks
sorry too many questions??

[Blackdog_kt]

In reality it should function just like the Spitfire: two settings, auto-lean and auto-rich.

In the sim the lever moves through the entire range (instead of snapping into place in the top and bottom position like it does in the Spit), but i don't know if this means the mixture is gradually adjusted (ie, fully manual) or it's indeed semi-automatic.

For example, the Blenheim had semi-auto mixture too but the levers in the real aircraft did move through the entire range (they do too in the sim): lower half (1%-50%) was auto-rich and upper half (51%-100%) was auto-lean, but the manual advised to set them to the edges anyway just to be on the safe side (in terms of control linkage movement tolerances).

Maybe the Hurricane's controls were similar?

Essentially, it's like having the same car using paddle shifters on the steering wheel in one model or using a normal stick shifter in another model: the stick shifter moves through all the positions but the only effective ones are where it engages a gear.


Now, as to mixture restrictions, lean mixture has the effect of raising engine temperatures. That's why using combat power is better done with rich mixture. Also, throttling way back in an abrupt manner might cause a cut-out in the engine (as opposed to smoothly setting moderate power for cruise and leaning for fuel economy) and that's why the Hurricane's controls were designed that way to prevent it.

[Das Attorney]

I jst had a look in the sfs files for the Hurricane and Spit for info on the two mixture controls.

In the respective fmd files they have the following methods of operation for the mixture control:

Hurricane

PHP Code:

EngineMix           Slider 


Spitfire

PHP Code:

EngineMix           Toggle 


And as we know, the Hurri has a slider and the Spit a 2 position selector.

In the rolls-Royce.emd, the [MerlinIII-RG-Hurricane] and [MerlinIII] both have this in common:

PHP Code:

Carburettor         RollsRoyceFloat DiffuserBore 6.1 cm OrificeSlowFast 1.0 sec Heater AutoEngineOil Altimetric DensityRatio Dresser BoostDriven Input +4.5 lbsqin to +6.25 lbsqin Output 1.0 to 1.01 


and

PHP Code:

Mix                 Slider Multiplier Range 1.21 to 0.87 


So, it looks like the engines operate using exactly the same parameters, but the selector in the Spit I is limited to just x 0.87 or x 1.21 as a richness multiplier and in the Hurricane, the entire range is available (like x 0.98 for example). I'm not totally sure, but it seems to suggest that.

[bob_baer]

Do you usually keep it rich and turn to weak only in calm cruise?

[TomcatViP]

Yes at very low rpm cruise and alt >4km

At lower alt I didn't find a satisfactory lean mixture level due to overheating concern (I like to engage a fight only with a cool engine)

[ATAG_Doc]

Thanks for the info. I didn't know that. I cannot fly the hurricane just because I'm always spewing black smoke and sputtering. lol So that thing is not a slider huh. But it is but its either up/down?? Should snap but not?