Apparently helicopter piston engines are kept in the mixture full rich position when flying. Even at higher altitudes. I checked through the real handbook of the G2 and there is no mention of leaning the engine at higher altitudes as you would do on a piston normal-aspirated fix-wing aircraft.
However, when I tried to take off at KTEX airport elevation 9000’ MSL, the helicopter loses power and settles back onto the ground. After leaning the engine the same way I would lean a fixed-wing aircraft, I managed to take off, fly around the airport, hover, and land.
Either the engine is modeled wrong in that it was supposed to produce power at 9000’ or the general rule of helicopters to be flown in the full rich position (that goes against my experience and knowledge flying fixed-wing aircraft) is wrong and the G2 is correctly modeled.
Other forums with real pilots did mention the full rich mixture for R22 but I did not see a mention of the G2. Some users on this forum brought the subject up in the main G2 discussion.
Please help me investigate if the model is correct for the 9000’ elevation.
Detailed steps to reproduce the issue encountered:
Place the Cabri G2 at airport KTEX (elevation 9000’) with the default settings engine started and ready for departure. Weather clear sky with no wind, standard temperature. Try to take off with the mixture fully rich.
EDIT: Changed this post from a bug report to a discussion.
This depends mainly on your weight, the air temperature and air pressure (look up density altitude).
For the best performance you should fly at 50 kt IAS (Vy), any faster or slower airspeed will require more power.
That’s for flying… Hovering takes much more power.
It is actually quite realistic, that you can’t take off at a 9000 ft airport.
That is why it is so important to understand all the charts in the performence section of the flight manual.
For taking of you would need at least in ground effect hover performance (excluding a running takeoff, where you slide on your skids until you get fast enough to take off).
A strong headwind will be your best friend, reduce weight and have a lot of space to build up speed while you are still in ground effect (try to think of it like a takeoff run in a fixed wing aircraft). Build up speed until you hit 50 kt and only then increase your altitude.
Thanks for the effort in explaining and elaborating on this topic.
If I was to start the Cabri at KTEX for example, with full rich, should I be able to fly still? Let’s assume I made the helicopter light and the temperature is a standard day. Density altitude 9000’ as well.
My experience was that the helicopter loses power and settle back. By losing power I mean it really loses a lot of rotor RPM. I then leaned it like a C172 and whalla I was flying like I was at lower altitudes.
Am I right to then file this bug, and the issue here is that on 9000’ feet the engine should still allow me to take off and accelerate to 50kts and beyond with the mixture in full rich? Or is it more like do not touch the lever. Stay away from 9000’ airports. Can it lean like an aircraft piston or is it just Rich and a few degrees later in cut-off with leaning in between?
Would you please mind trying this out yourself and see what you are experiencing?
Just trying to give positive feedback to MS and the team for a better flight model. Maybe they are aware of it and already on it. But it is not mentioned on the known issues page.
There is an O-360-J2A engine with ma-4spa carburetor. If you have them on a plane like Cessna, and if you are going to take-off from an airfield placed at 9000 - it is OK to lean (ma-4spa carburetor are not to be leaned before 5000 feet) because the plane accelerates quickly and you will not overheat it most likely - the airstream helps a lot, there is some air cooling. Those engines use fuel not to overheat the engine, like a cooling liquid. Can you accelerate the G2 to the safe for temperature limitations airspeed, where the air is cooling effectively - quick enough? What if you need full power for emergency? Leaning the engine is not always simple - you have to do it slowly at cruise or full open throttle settings. Lean to peak temp and then rich to 50-100 degrees rich of peak on EGT gauge if you have it. In the simulator you can do whatever you want. However there is a reason they do not lean in their real flights.
Nice explanation also thank you. Make sense. The cooling of a helicopter engine is more critical because in a hover there is not much airflow such as in a flying C172.
So it is also about entering the hover and accelerating to say 50knots to get that airflow going.
Thanks, I did consult the manual before and counted the word “Mixture”. It came up 7 times if I remember correctly and never was leaning mentioned. Only the ones you also quoted.
the rich mixture and lack of leaning are partly due to the cooling of the engine
What remains is the reason for this bug: a) is the G2’s engine behavior at 9000’ correctly modeled? Should the engine behave as it is? The graph says I can hover at 9000’ but the sim did not reflect that.
The helicopter was certified for 13000’ What will happen if I take off at say my home airfield’s 5584’, and climb to 9000’ in the cruise (rather boring to climb that high) without leaning?
===> Please before anyone replies, please also try this flight for yourself. <====
KTEX 9000' ISA+10 1232 lbs take-off weight, no wind.
I’ve already made a test up to 14000 ft, though with reducing mixture nearly to 50%, as mentioned through the link below
“doing the mentioned way, make me to be able to climb to around 14000 ft in MSFS, with take-off from 4CA1 and landing on KLAX I think 50% is nearly the limit though on ground the engine is able to accept very low fuel flow in MSFS”
I will re-check 9000 ft with maintaining the mixture on Full RICH and conditions, as requested
Just to mention a point, I found maintaining sufficient forward speed helps a lot while climbing to 14000 ft previously, thus accelerating the climb and reducing time to achieve
30-40 kts were enough
I could not even reach a liftoff for a few seconds in my original flight. Therefore could not even reach 50kts. Unless someone pushed me over the cliff at KTEX.
At the current altitude on KTEX, the extreme limit for ISA + 10 is 7°F / -13.9°C, in order to be able to at least taxiing, just floating (without climbing or descending)
ISA + 10 : -25°F / -31.7°C allow to climb a bit on low power limit
With an OAT of -3 °C / 26 °F (which is ISA at 9000 ft) I can only hover IGE with carb heat set to cold.
With carb heat cold I can take off normally from the IGE hover.
With carb heat on auto I need to do a running take off, but still manage to get airborne.
Bear in mind that you need a very stable hover, in reality unnecessary pilot input will greatly increase your power requirements in a hover (not sure how accurately this is modeled in the sim).
But overall I feel like everything feels very accurate and that the relative power requirements for the different phases of flight seem to be realistic.
The only thing that throws me off is the power indication of the multiple limit indicator (MLI), but I have already created a bug report for that.
