Flight ceiling, How much is it ?

[Tarmak]

Hi Chinook'pilots,

I noticed that when I reached a certain altitude (around 9000ft),
 a loss of power appeared and it was impossible to increase my altitude...
 Do you think this is normal? 
Have we reached the altitude limit of the CH47?

Edited September 13, 2024 by Tarmak

[Hiob]

Well that would be below its max. service ceiling, but which altitude can be reached depends on other factors like temperature and weight.

[Tarmak]

Hi Hiob,

Indeed, it was a mission on Caucasus with negative temperature, 
and regarding the weight there was full fuel and no additional load.

Thanks

[Hiob]

On 9/14/2024 at 8:07 AM, Tarmak said:

Hi Hiob,

Indeed, it was a mission on Caucasus with negative temperature, 
and regarding the weight there was full fuel and no additional load.

Thanks

It‘s usually hot temps that affect the performance negativity. But the weight would definitely be a factor.

Also - I got the numbers from wikipedia so probably right, but could be wrong either.

Did you test with lower weight? Did you reach higher altitudes?

[LuseKofte]

I love the hook, I really do. But none of what we see today is ready enough to be compared to reality. 
It’s too early access. You should have no problem going higher with full tanks and no cargo. In fact if it’s nothing wrong with missions online I have yet to see any limitations in weight. You can fill it up with troops , take full internal cargo and still sling load the heaviest cargo DCS offer with no seemingly difference in performance

[dahui]

On 9/13/2024 at 3:05 PM, Tarmak said:

Hi Chinook'pilots,

I noticed that when I reached a certain altitude (around 9000ft),
 a loss of power appeared and it was impossible to increase my altitude...
 Do you think this is normal? 
Have we reached the altitude limit of the CH47?

 

No, the correct performance is not implemented yet.

9k Feet, NegativeTemps and just fuel is definetly way not enough to bring the chinook to its limit

[TKhaos]

Boeing state the maximum ceiling for the Chinook is 20,000ft, although there have been a couple of cases where it's been pushed 10% higher than that. In the UK the RAF operate with 15,000ft maximum density altitude based on there operations.

So 9,000ft sounds a little low unless you were fully loaded with fuel and cargo, which in your case you weren't as you only had fuel. Guess flight characteristics aren't fully implemented yet.  

[Marsvinet]

I managed to haul 6000lbs of cargo up to a 16000ft peak and I estimate that I had ~75% fuel left at that altitude. The last ~3000ft up to the peak was at a snails pace, with the engines pegged at 99.2% RPM, with torque at ~65% if I remember correctly. Any more collective and I started dropping like a brick due to the drooping. 9000ft sounds like you are doing something wrong or expecting too much out of the airframe.

[jubuttib]

Interesting, I was recently playing Pretense and, being the aspiring young man that I am, loaded up with 10 000 kg of supplies (some 22 000 pounds...) on roughly one third fuel, and set about crossing the Caucasus mountains in 10°C FAT conditions.

This did not go very well.

I got pretty much stuck at around 9000-9500 feet, after cranking the FADEC RPM to max to try and get some extra out of the Hook, but yeah, RPM was dropping as did the torque, and I couldn't really find a balance between moving fast enough to avoid OGE hover conditions, and maintaining altitude, let alone gaining it.

But again, this was with nearly maxed out load, took something like 75-80% torque just to get into IGE hover in the first place, I would expect a more lightly loaded Hook to easily handle that situation.

Thankfully I did manage to find a path through the valleys to get where I was going in the end...