Fuel Mixtures: Dr. I and SPAD

[Champagne]

In combat for the Dr. I, 80 percent mix seems best to me. Thoughts?

 

I need advice on this and on fuel mixture for the SPAD.

 

Thanks.

[US63_SpadLivesMatter]

Watch your rpm and adjust until you're getting the best revs.  Generally optimal mix will be lower at high altitudes, and higher at low altitudes.

 

Just be cognizant of where you're at, and adjust as needed.

[LukeFF]

Don't pay any attention to the silly percentage values - that just teaches bad habits. Just do what @hrafnkolbrandr says.  

[Zooropa_Fly]

As indeed Hrafn says..

You can use the scale on the lever as a visual guide, remembering you're likely looking at it from an angle.

I find 8.5 (85%) on the Dr1 is about max revs at lower alts, nearer 80% in the Spad.

It's not overly sensitive in most planes (RoF at least) so don't lose too much sleep over this ! Once you find the sweet spot a nudge or two in either direction isn't likely to make much / any difference.

 

And remebering it's a game, use the % if you want, maybe until you've visually fixed where the lever should be.

 

S!

 

[Sgt_Joch]

By looking at the smoke trailing behind the plane, you can tell if the mixture is too rich, ideally there should only be water vapor.

 

As to best mixture, it seems to be more of a range than an exact amount on the SPAD. I use around 70% at 2km, going down to 65% at 4km. 65% seems to be the lower limit at 2km. A range of 65-75% is good between 2-4km. I have done some rough tests, but no fine tuning yet.

 

If you dont want to use the %, you can read it off the instrument in the cockpit, but they use the same numbers, i.e. 0-100.

Edited October 5, 2018 by Sgt_Joch

[yaan98]

If modeled correctly in game, the DR1's engine would cut out below a certain rpm. I believe it is less than 600 or 700. Also, I believe the SPAD had some type of air control lever.

search on google:

"Below 6000 ft use of the altitude control lever will not perceptibly effect the power or rpm; but if the control is left shut after climbing to 3000 ft the petrol consumption will be unnecessarily high. To obtain the maximum air endurance...the altitude control lever should always be partially opened at heights of 3000 ft and over. The precise amount of opening should be determined by the tachometer reading, the control being opened to the point at which any further opening will cause loss of rpm. The throttle and altitude control levers open and shut in the same direction. The pilot pulls them both towards him when climbing, and pushes them both away from him when diving". (from the 300 hp Hispano-Suiza maintenance manual).

Edited October 5, 2018 by yaan98

[HiIIBiIIy]

4 hours ago, Sgt_Joch said:

By looking at the smoke trailing behind the plane, you can tell if the mixture is too rich, ideally there should only be water vapor.

Not in the DR1, you should see a blueish smoke from the oil.

[Sgt_Joch]

SPAD test:

-setting of 6.5 to 7.5 (i.e. 65-75 %) give the best RPM at 2 km;

-setting of 6 to 7 (i.e. 60-70 %) give the best RPM at 4 km;

 

Other question: does temperature have an impact? The SPAD overheats at over 100 c. Since there are no instructions, I have have been setting the radiator to keep the temp in the 50-70 c range. QMB starts you off at 60 c in flight.

Edited October 6, 2018 by Sgt_Joch

[unreasonable]

It is not so much that temperature has an impact on optimum mix as that mix has an impact on engine temperature.  I always found in RoF that overheating was quite rare - the radiators on the in-lines seemed good enough for european conditions. What could be a problem was over cooling. If you have longish high altitude patrols in winter it became very hard to keep the engine warm. Less of a problem in Career, but when I tried PWCG, which puts you at higher altitudes, this was certainly a problem.

 

Running an engine a leaner than what is optimum for rpm may stop it cooling quite so fast, and IIRC this worked to a degree in RoF, although I have not experimented much with FC yet.  Should be easy enough to check on our winter maps or the ME.

[ZachariasX]

1 minute ago, unreasonable said:

I always found in RoF that overheating was quite rare

"Albatros, open rads!!"

[Sgt_Joch]

I meant effect of temperature on engine performance. Running cool or hot does not seem to have any effect, as long as you dont overcool or overheat.

[US103_Baer]

What hrafnkolbrandr and lukeFF said. Adjust while watching tacho. 

 

Can't speak for the Dr1 but the Spad will need close attention to get max performance. Helpful if you can adjust mixture with one hand or without  moving hands too much.

 

Only other thing i'd add is it helps to know roughly what mixture you'll need BEFORE diving a couple of thousand metres onto an enemy. Getting down there and then having only half power to zoom or extend is a sure way to die.

 

Oh, and once engine is started on ground, adjust to optimal low level mixture before takeoff. Saves faffing about after takeoff. In the Spad that's around 80%, you can fine tune it once you start to climb out.

[kestrel79]

Do any of the current ww1 planes have an Altitude Throttle? I remember that from RoF, and I see it's now listed in the key binding in BoX. I don't think any current planes use one though?

[SYN_Mike77]

12 minutes ago, kestrel79 said:

Do any of the current ww1 planes have an Altitude Throttle? I remember that from RoF, and I see it's now listed in the key binding in BoX. I don't think any current planes use one though?

When the D7 comes out, it should have an altitude throttle.

[yaan98]

Keep in mind that fuel/air mixture vs air density was not fully understood at that time and engine modifications were added to keep them from consuming too much fuel and losing power at high altitudes (e.g. above 10 to 12,000 feet). I would really like to read how pilots used the fuel and altitude levers during flight at high and low altitudes with clear explanations on how the controls worked on each aircraft. For example, I copied this from the aerodome forums:

 

Chapter 5

Flight and maintenance (Breguet)

 

1. In-flight control of the engine

 

General note: With high-powered stationary engines, such as Fiat 300hp, one should never disengage or engage the ignition when the engine is running with full throttle.

 

All controls of the engine, especially throttle and air levers have to be moved gently and smoothly, never with sudden and jerky movements.

 

Ground handling: Check that ignition switch is off (coupe), in position 0. Mechanic squirts a small amount of petrol* into each cylinder, raises the floats of the carburetor to induce a richer mixture, and then turns the propeller rigorously around couple of times.After this, mechanic takes his distance from the propeller and announces that engine is ready for the start. (contact) Now pilot sets quickly throttle lever approx one-thirds forward, pushes ignition lever to delayed position, sets ignition switch to position "1-2" and engages the start current. (either by pressing start button if the aircraft has battery or by rotating the start magneto). As soon as the engine has started, let it idle slowly, using approx. 400-500 rpm until thermostat shows 50-60°C. Meanwhile the condition of different magnetos are tested. Only after this throttle is _slowly_ increased until full rpms are reached. This is only allowed when both oil and water temperatures have reached their normal levels, thus avoiding seizing the engine due to thick oil. Oil circulation is normal when the gauge indicates approx. 8 at idle and approx. 10 meter pressure with full rpm. 

 

Before take-off the magnetos are still on full rpm and the reduction of rpms is 30 rpm when only the magneto on intake side is connected, and the reduction is approx. 20rpm when only using the magneto on the exhaust side. Maximum rpm of the engine is 1600.

When everything is correctly and thermostat shows approx. 70°C take-off can be done. Cooling gills must be then fully opened, ie. lever pushed forward.

 

Flying: For the climb the engine is run with full rpm, ie. throttle lever is in fully opened position. After reaching 2000m of altitude, it's necessary to adjust more air for the engine (NOTE: to lean the mixture). The air lever is pulled then towards oneself one notch at a time when altitude increases, while rpms are monitored to avoid deceasing the rpms due to increased air. Suddenly opening the air lever may cause a fire in the carburetor. After reaching the desired altitude rpms are lowered.

 

If the water temperature during the flight starts to drop, the cooling gills should be gradually closed by pulling the lever towards oneself. Water temperature is kept between 70 and 80°C.

 

During the take-off it is recommended to use the upper fuel tank. For this the 3-way-switch on left (uppermost) is put to position number III (mark upwards), the needle valve on lowest position on left is closed (turn clockwise) and the right side needle valve is opened (turn anti-clockwise). Now the petrol from upper tank will flow to the carburetor by gravity, thus a possible malfunction in fuel pump will not abort the flight in the very beginning.

 

After reaching the normal altitude, the lower tank will be used. This is done by turning the 3-way-switch to position number I and the lower tap on left is opened. Now the lower tank is slowly drained using the pump. The petrol in upper tank has to be spared in the case of possible fuel pump malfunction. Similarly, when the lower tank is empty it's easy to switch using the upper tank with switch position number III.

 

Usually the upper tank is used too with fuel pump, so that the 3-way-switch is in position number II and the lower tap on the left is closed. In this case the pump will move the fuel to the carburetor with greater pressure, thus with better reliability compared with position III. So, position III is only used during take-off, when changing the fuel tank and when the fuel pump doesn't work.

 

Landing procedures - Throttle is slowly decreased with care taken that enough rpms are kept for easing a possible power-up. During the landing also the air lever is closed. And the cooler gills are closed, but the water temperature is close watched to avoid it cooling below 50°C. If the water is cooled too much, the engine will not power up when needed.

 

At the touch-down the rpms are lowered to the lowest, ie. idle. After arriving to the hangar, the engine is let to spool up to max. rpms couple of times for removing the possible carbon and dirt build-up from valves and tubes*. After this ignition is set to off and immediately the throttle is fully opened, so that a fresh gas mixture goes into the cylinders for future use.

Petrol is cut off by closing the right and left needle valves and by setting the 3-way-switch into position I.

 

Before each start and take-off the oil switch on the left has to be checked to be open. After the flight it has to be closed to prevent too much oil seeping through the pump into the crankcase.

Edited October 20, 2018 by yaan98

[Poochnboo]

In the SPAD it's that radiator that you'd better be worried about. Make sure you open and close when needed. If your engine gets either too hot OR too cold she'll quit on you. In ROF I decided to bind the radiator to the throttle. When I pushed the throttle forward the radiator opens , when I pull it back it closes. It works well and my engine never quits on me. Unless it takes a Hun bullet.

[J2_Trupobaw]

If you run with your radiator always open you will lose RPMs, especially in winter and on high altitude. YOu need to keep the coolant above 80 deg Celsius.

Edited October 25, 2018 by J2_Trupobaw

[Sgt_Joch]

I only noticed this recently, but the SPAD water temperature gauge has temperatures listed for each altitude. I would guess that is the upper limit?

Edited October 26, 2018 by Sgt_Joch

[unreasonable]

21 minutes ago, Sgt_Joch said:

I only noticed this recently, but the SPAD water temperature gauge has temperatures listed for each altitude. I would guess that is the upper limit?

 

 

Since the numbers are the boiling point of water at those temperatures, then yes it is the maximum if the SPAD cooling system was unpressurized, which I assume it was, or even if very weakly pressurized then a safe maximum allowing a small safety margin. I do not know which. 

 

Quite how this is implemented in FC as yet I have not tested:  it is such a mess with the Spitfires that I am rather waiting for the developers to clean up some of the engine management issues before I can be bothered to fly again.

[Sgt_Joch]

I see there is a red line at 60c and 80c, so I would guess optimum temp in RL was in that range.