need evidence Low RPM at 60% Torque at altitude

[Rabies]

I've put a simple mission together (cold start) to rescue troops at elevation, in bad weather. Apart from fuel, the chinook is empty. I have noticed that I begin to lose rpm when I approach 6000ft ASL, and it continues to deteriorate as  I climb, the whole time my torque is around 55-60%. At around 7500ft my RPM is 74% and I'm still airborne LOL 

 

 

 

dcs.log afghan test.trk CH47_2-ship_QRF_Transport_V2.miz

[Mr_sukebe]

That’s very normal for helicopters

[Rabies]

4 hours ago, Mr_sukebe said:

That’s very normal for helicopters

Surely not at 7000ft in a chinook, and still remain flying with your rotors at 74%! 

[Mr_sukebe]

Don’t take my word for it, read this example:

https://billingsflyingservice.com/ultimate-heavy-lift-helicopter/#:~:text=CH-47 Chinook%3A Lift Capacity at Altitude&text=For example%2C at 5%2C000 feet,level maximum of 26%2C000 pounds.
 

 

[Rabies]

11 hours ago, Mr_sukebe said:

Don’t take my word for it, read this example:

https://billingsflyingservice.com/ultimate-heavy-lift-helicopter/#:~:text=CH-47 Chinook%3A Lift Capacity at Altitude&text=For example%2C at 5%2C000 feet,level maximum of 26%2C000 pounds.
 

 

I know performance deteriorates at altitude and temperatures. However, this is an empty hook, struggling to get above 7000ft, with rotor dropping to 74%. However, if I place a hook already in the air at 13,000ft, it’s maintaining rotor rpm at 100%.  

Edited November 3, 2024 by Rabies

[Lord Vader]

Spawning an helicopter at high altitudes is not really a good comparison as it's not a realistic setup.

At this point, the flight model and performance of the DCS: CH-47F is still work in progress and may be subject to several improvements. 

Regardless, if you have performance documentation to support the idea that those RPM to Altitude ratios are incorrect, please send that unclassified publicly available documentation to @BIGNEWYand we'll have a look. 

[Emppu]

I don't own afghanistan map and am unable to check your track, could you verify if these are probably icing conditions?
I'm observing a maybe related issue in caucasus, winter and snow. After prolonged flying at sea level in -5°C, NG rises at same power setting, after about 30 minutes NR begins to drop below limits, and continues till generators come offline.

If this is modelled icing on purpose - great! I'd appreciate a confirmation by a developer

Gesendet von meinem XQ-AS52 mit Tapatalk

[47_Driver]

On 11/1/2024 at 10:22 PM, Rabies said:

I've put a simple mission together (cold start) to rescue troops at elevation, in bad weather. Apart from fuel, the chinook is empty. I have noticed that I begin to lose rpm when I approach 6000ft ASL, and it continues to deteriorate as  I climb, the whole time my torque is around 55-60%. At around 7500ft my RPM is 74% and I'm still airborne LOL 

 

 

 

dcs.log 396.41 kB · 0 downloads afghan test.trk 18.22 MB · 0 downloads CH47_2-ship_QRF_Transport_V2.miz 546.39 kB · 0 downloads

What is the Outside Air Temperature at altitude in your scenario? Don't look at TQ in this case, you need to be looking at NG. You're likely running into NG Limiting due to atmospheric conditions/aircraft configuration. This would give you similar indications to what you are experiencing. However, (and keep in mind this module is still WiP), the aircraft would not remain airborne at 74% NR. Your Generators would have failed long before that as well and you would be descending rapidly, whether you wanted to or not.

[BIGNEWY]

a reminder please do not share real life manuals here on the forum, if you need to PM us. 

thank you 

[dahui]

On 1/2/2025 at 10:19 PM, 47_Driver said:

What is the Outside Air Temperature at altitude in your scenario? Don't look at TQ in this case, you need to be looking at NG. You're likely running into NG Limiting due to atmospheric conditions/aircraft configuration. This would give you similar indications to what you are experiencing. However, (and keep in mind this module is still WiP), the aircraft would not remain airborne at 74% NR. Your Generators would have failed long before that as well and you would be descending rapidly, whether you wanted to or not.

with 74% NR, the Generators are your smallest Problem

So on the Chinook the first Limit is usually NG? Not even MGT? Thats interesting

Edited January 20 by dahui
typo