LA-5 cowl flaps

[beresford]

I tried flying this bird for the first time a couple of nights ago, and went straight to 3000m before blowing the engine. I went back to check Chuck's Guide and found the bit I'd missed, that both cowl flaps have to be fully open for take-off.

 

OK, so you start with both flaps fully open and then close them as much as you dare. But how do you use the separate inlet and outlet controls intelligently? Is it a case that the outlet flap controls heat release and the inlet controls forced cooling, and therefore you should close the inlet first?

 

I guess that the game doesn't anticipate you changing the cowl flaps that much because with the keyboard mapping you need hands like Meadowlark Lemon to shift the flaps one-handed.

[Legioneod]

Personally I just keep the inlets open most of the time and adjust my outlets as needed for cooling, probably not the best way to do it but that's what I do. Another thing to check is make sure it's not your oil overheating, it's controlled by different controls.

 

I think your inlet and oil shutters cause very little if any drag so it's best to keep them open most of the time, the outlets are the ones you want to constantly monitor and control.

Edited September 11, 2018 by Legioneod

[Frenchy56]

Inlet cowls basically have minimal effect on speed so keep them 100% at all times except steep dives.

Open outlets as you need them.

Don't forget the oil radiator.

Edited September 11, 2018 by Frenchy56

[Sgt_Joch]

the inlet cowls cause no external drag. You keep them fully open all the time. The only time you need to think about closing them is when descending say to land when you might overcool the engine.

 

even the outlet cowl can be kept at 10-20% most of the time without having an issue with cylinder head temp.

 

the only one you really have to watch is the oil radiator. 60-80% if you don't want to worry, or 40-60% if you keep an eye on it. I don't rely on the overheat warning, but follow the recommended specs. (note: La-5fn specs).

 

On the whole, the engine is fairly easy to keep cool with minimal oversight, unlike the engine in the Yak-1 which tends to overheat a lot more easily.

[peregrine7]

FWIW I did some testing about a month ago and the drag values were:

La5 Ser8, Altitude <50m. Boost on, prop pitch 100%, mix 100%. (Kuban, summer). Intake Shutter 100% open for all tests.
540 km/h Oil Closed, Outlet Closed, Cockpit Closed

510km/h  Oil Closed, Outlet Closed, Cockpit Open

498km/h Oil Closed, Outlet Open, Cockpit Closed

535km/h Oil Open, Outlet Closed, Cockpit Closed

Cockpit Open - 30km/h

Outlet Cowl Open - 42km/h

Oil Shutter Open - 5km/h 

Supercharger (at high speed) 
2,500m - Supercharger stage 2 provides 4km/h difference. This suggests the La5's break even is lower than the manual states. However this may be dependent on the airspeed(?)

These values are from memory so may be off by a few km/h. The gist is intact

Due to this in general you should keep your oil open at all times, outlet closed. If the oil gets overcooled (winter) then close it a little, on some winter maps both outlet and oil need to be closed completely to keep the engine warm. If the oil gets too hot open the outlet as needed (usually less than 30%), the outlet affects the oil temp as well. At altitudes above 2,500m it is rare to need any outlet at all - just be sure to open it up a little if you've dived way down and are climbing back up on a hot day.  Intakes are always open as they give no drag.

Edited September 11, 2018 by peregrine7

[CSW_Hot_Dog]

15 minutes ago, peregrine7 said:

Supercharger (at high speed) 

2,500m - Supercharger stage 2 provides 4km/h difference. This suggests the La5's break even is lower than the manual states. However this may be dependent on the airspeed(?)

 

No, it is because you used boost which increased manifold pressure. The higher manifold pressure the lower alt supercharger gear 2 for optimal engine performance and 3500m in flight manual is intended for throttle wide open without boost.

Edited September 11, 2018 by Hot_Dog

[peregrine7]

10 hours ago, Hot_Dog said:

 

No, it is because you used boost which increased manifold pressure. The higher manifold pressure the lower alt supercharger gear 2 for optimal engine performance and 3500m in flight manual is intended for throttle wide open without boost.

 
Boost was off for the test at 2,500m.

[69TD_Hajo_Garlic]

I'm sure it's not ideal but I fly around with inlets and oil rads open all the way and outlets only open arround 25% unless I'm in a level chase or a scenario that requires some adjustment.  Der sheriffs how to la5 video would probably get you more optimized.