Real Engine 1.4

[AndiKunzi 62]

I do use P3D V4.

1. If I set the engine speed to 3350 max and the gear ratio to 1.5, the engine speed is displayed: way after redline.

3. POH values are for max. take-off mass or must be corrected. The performance with 2 pilots only (default on my plane) is comparable to an almost fully loaded C404.

4. Increasing beta max. prevents the prop to reach max. pitch at higher TAS. Using default setting, the prop exceeds redline with feathered prop in cruise at FL250.

May be there's a difference between P3D and FSX. My aircraft.cfg also includes those variables below the headline "Flight tuning". I tried to adjust the parameters because I use the simulator for serious training, especially for emergency procedures which cannot be done safely in a real plane. We operate a real world C421C, the pressurized sibling of the C404. (Still looking fpr an Aspen EFD1000 for the sim.)

I've adjusted flaps drag (and lift), prop beta max, engine displacement, compression ratio and critical altitude so far. When I'm ready, I'll post the figures here.

[FDEdev 955]

14 hours ago, AndiKunzi said:

1. If I set the engine speed to 3350 max and the gear ratio to 1.5, the engine speed is displayed: way after redline.

3. POH values are for max. take-off mass or must be corrected. The performance with 2 pilots only (default on my plane) is comparable to an almost fully loaded C404.

4. Increasing beta max. prevents the prop to reach max. pitch at higher TAS. Using default setting, the prop exceeds redline with feathered prop in cruise at FL250.

1. You did change the engine speed and added a gear ratio in the cfg file?   It doesn't work that easy. You can't simply alter values in the cfg file without doing the major work in the air file!!!

3+4 are not valid if you have changed the cfg file with your 'new' engine.  With the default FDE I get approx 1500ft/min at MTOW which is correct according to the POH.

Stall speed is also correct with flaps up/down, hence flap lift seems to be correct.

 

[AndiKunzi 62]

At default settings:

Fuel Flow is way too low since engine power is not correct. Thus, the power settings are incorrect, too. FF in the correct range are important checks at take-off and when setting climb power.

(The leaning model is also not working as it should: on a TIO engine with wastegate controller, the engine controls do not have to change with altitude. That's something which would have to be changed in the air file. Somebody with knowledge here about how to do that?)

Drag / sink rate is way too low with gear and flaps down. Those are split flaps which do produce a lot of drag. Stall speed is not affected by flaps drag coefficient, it is affected by flaps lift coefficient (and mainly by wing loading, of course).

If you pull the engines in a real life C404 or C421, the glide ratio in landing configuration is 1:stone. 

(I'm a real life CPL/ME/IR with > 1000 h ME time)

[FDEdev 955]

2 minutes ago, AndiKunzi said:

At default settings:

1. Fuel Flow is way too low since engine power is not correct. Thus, the power settings are incorrect, too.

2. Stall speed is not affected by flaps drag.

1. Not experiencing the fuel flow/power setting problems here. You know that mixture simulation and hence leaning in FSX/P3D is completely wrong?

2. You wrote that you changed the flaps lift!

[AndiKunzi 62]

Yes, leaning is wrong, but power settings are working quite well on FSX/P3D (MP, RPM, FF for given percentage of MCP), except for the position of the mixture levers.

One of the most important checks during T/O is FF within T/O range. If it is low, the T/O has to be rejected.

For the Cessna 400 series, it is FF in the white arc.

Typical cruise for a C404 / C421 is 60 %, 30 inHG, 1700 RPM, 36 GPH / 214 pph.

[FDEdev 955]

4 hours ago, AndiKunzi said:

Typical cruise for a C404 / C421 is 60 %, 30 inHG, 1700 RPM, 36 GPH / 214 pph.

Using your example (which isn't mentioned in my POH) I get 212pph (50° ROP).

As the climb performance apparently also greatly differs from the POH data on your 404, maybe P3Dv4 really changed the FDE calculation.

I'm still using FSX after I got a refund for P3Dv4. 

That said, in the few weeks I used v4 I unfortunately didn't notice any difference concerning the FDE.

 

[AndiKunzi 62]

Do you know how to have a suction pump on both engines?

If I have a failure of the critical one (L), the suction fails. All twins must have suction pumps on both engines and a gauge for both pumps, usually one pressure gauge with 2 red mechanical pop-up indicators.

If I train other pilots, I want to alter the engines which go off, but not losing suction.

[FDEdev 955]

2 hours ago, AndiKunzi said:

Do you know how to have a suction pump on both engines?

simply add a second one in the cfg file.

[vacuum_system]
max_pressure=5.0
vacuum_type=1
electric_backup_pressure=4.5
engine_map=1,1,0,0
 

 

[AndiKunzi 62]

Thank you very much!
That helps!

[Les Parson 99]

I have returned to the C404 in anticipation of the upcoming C421C. I absolutely loved the Flight 1 C421, which seems like about 50 years ago. I also have a 1980 C404 POH and a 1979 C421C POH. I never realized engines are nearly identical: 

C404 

GTSIO-520-M: Six-Cylinder, Geared, Turbocharged, Fuel-Injected Engines. 375 Rated Horsepower at 2235 Propeller RPM and 40.0 Inches Hg. Manifold Pressure to 16,000 feet.

C421C

GTSIO-520-L: Six-Cylinder Geared, Turbocharged, Fuel-Injected Engines. 375 Rated Horsepower at 2235 Propeller RPM and 39.0 Inches Hg. Manifold Pressure to 20,000 feet. 

When you say Fuel Flow is low and Drag / Sink rate is low, can you detail steps to correct .air file?  I really wish there was someone equal to Brent Stolle with the expertise to adjust FDE dynamics as exist in real-world ops. As I understand it, he is no longer in engaged in flight sim stuff. 

I recently made the switch from FSX to P3DV4, more out of desperation with continuous FSX freezes with Win 7/64. I downloaded the C404 yesterday for P3DV4 and can perform some testing as it relates to FF as mentioned above. I like the beastly feel of the 404 and would like to see it as close as possible to real-world. I feel this is a real opportunity as there are apparently folks on this thread with real time on C404/C421. Moreover, when the 421 is released, hopefully it will be close to ideal as it relates to performance accuracy. 

 

Les Parson

[FDEdev 955]

39 minutes ago, LDP1949 said:

 I downloaded the C404 yesterday for P3DV4 and can perform some testing as it relates to FF as mentioned above. 

Can you confirm the FF figures from the POH/FSX in P3Dv4 and the, according to AndiKunzi, way too low climb rate?

Btw, glide ratio with both props feathered is also correct...at least in FSX.

[Les Parson 99]

I will try and get it done today.

[AndiKunzi 62]

6 hours ago, LDP1949 said:

When you say Fuel Flow is low and Drag / Sink rate is low, can you detail steps to correct .air file?  I really wish there was someone equal to Brent Stolle with the expertise to adjust FDE dynamics as exist in real-world ops. As I understand it, he is no longer in engaged in flight sim stuff. 

T/O FF is roughly 42 GPH/engine, so about 250 pph, and must be in the White arc. Cruise climb (MP and RPM end of green arcs) is done with the FF at the blue triangle at 145 pph as per book,. In reality, a bit richer to keep EGTs down.

Sink rate in landing config is in a way that you can make really steep approaches at 140 KIAS. However, I can't tell the numbers without trying it in the plane and recording that. The C421C is also a bit different, probably.

However, if you arrive at medium loadings at the fence at a Speed of 100 KIAS and pull the engines to idle, you just don't float down half the runway until you can touchdown near stall. The plane just sits down quickly.

If someone who is involved in developing the C421 would come to Stuttgart, I could do a performance recording / comparison flight (just in case this post is read by the right person). 

 

[FDEdev 955]

1 hour ago, AndiKunzi said:

However, if you arrive at medium loadings at the fence at a Speed of 100 KIAS and pull the engines to idle, you just don't float down half the runway until you can touchdown near stall. The plane just sits down quickly:

For this effect you need to switch to x-plane as FSX/P3D doesn't simulate prop wash / loss of lift over the wings.

Nice side effect when using x-plane (and basically every other sim except FSX/P3D); you will get the correct sound when changing power/prop RPM.

That's a real show stopper and immersion killer IMO in FSX/P3D. 

[Les Parson 99]

P3DV4 Data: 

TAKEOFF: 

During takeoff roll, FF 31 GPH/engine, well below the white arc. TOW 6548; FLAP TO/APCH

CLIMB: 

Climbing out of 5000: 

MP - 33.6

RPM - 1900

FF - 21 GPH/engine

EGT - 1455F

CHT - 148F

IAS - 130 KIAS

CRUISE:

MP - 31.0

RPM - 1700 

FF - 15.3 GPH/engine - TOTAL LB/HR - 190

EGT - 1502F

CHT - 106F

IAS - 151 KIAS

TAS - 179 

TEMP - +7C / ISA +12

C404 POH CRUISE DATA: 10000 FT / MP 31.0 /RPM 1700 / STD TEMP -5

BHP - 62.2

KTAS - 176

TOTAL LB/HR - 220 

I should have checked the aircraft.cfg fuel scaler before I began. I will do that now as most Alabeo/Carenado require some adjustment. 

Any advice on how to adjust .air file is appreciated. 

Les Parson