Pitfalls of accelerated time

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Stratocruiser2
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Pitfalls of accelerated time

Post by Stratocruiser2 »

I don't know about anyone else, but on long overwater flights in the Connie I have tended to use accelerated time once of out of range of any shore based navaids, mainly because I don't want to sit for hours doing very little! I do however temporarily reset normal time over the Atlantic when getting close to the Ocean Stations (weather ships) just to allow myself time to get an accurate fix and then go back to accelerated time after setting a heading for the next leg on the autopilot.

I was conscious that accelerated time should be limited to a maximum of 4X, as advised in the A2A Connie manual, so I haven't tried to exceed this. I have however found that when flying on a setting of 4X, the aircraft can behave quite erratically with marked uncontrolled fluctuations in RPM and MP occurring intermittently despite leaving the engine on the recommended cruise settings. This can result in both RPM and MP exceeding the red line transiently and, if accelerated time is left on 4X for long enough, the effect appears to be an inevitable steady rise in engine temperatures, which I think on at least one occasion led to an in-flight engine fire. When the temperature gets too high I have tended to reset normal time for about 5 minutes which usually allows the engines to cool down. These uncontrolled engine fluctuations are not as marked if accelerated time is changed to 2X but they are still present.

Another issue related to the use of accelerated time which anyone contemplating using it needs to be aware, is that the Captain's Log still records in normal time although the distance flown is correct!

Please don't read this as a complaint - it isn't! It's merely a couple of observations which I thought I would share. The A2A Constellation is, in my opinion, the most perfect add on aircraft that I have ever purchased :D and I am very conscious that flying in accelerated time is not a reflection of reality. Indeed the Connie is not alone in this as many FSX aircraft behave quite erratically under these circumstances.

Bill

AviationAtWar
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Re: Pitfalls of accelerated time

Post by AviationAtWar »

Does engine/airframe time accumulate in real time or the accelerated time?

Stratocruiser2
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Re: Pitfalls of accelerated time

Post by Stratocruiser2 »

AviationAtWar wrote:Does engine/airframe time accumulate in real time or the accelerated time?
I just looked at the pilots hours and didn't notice the engine/airframe time. I will check that on the next transoceanic flight I make and let you know, if someone hasn't given you an answer in the interim.

Bill

AviationAtWar
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Re: Pitfalls of accelerated time

Post by AviationAtWar »

Thanks! I'd check myself but my sim will be down for a couple more days.

spesimen
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Re: Pitfalls of accelerated time

Post by spesimen »

Stratocruiser2 wrote: I have however found that when flying on a setting of 4X, the aircraft can behave quite erratically with marked uncontrolled fluctuations in RPM and MP occurring intermittently despite leaving the engine on the recommended cruise settings.
i can confirm that i have seen this. the first time i tried 4x, i would get a spike every 5 seconds or so where the manifold pressure and rpm would redline and then drop back to the original value.

however it is not 100% reproducible. i tried it again just now, and it seems to be working smoothly at 4x. i have no idea what is different between the two situations, unfortunately. i had been sticking to 2x and hadn't tried it since the first time, until i happened across this thread...

edit: one possible difference is that i'm not in career mode at the moment, i will give 4x a try when it is turned on during the next flight

cheers
-andy crosby

Dogsbody55
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Re: Pitfalls of accelerated time

Post by Dogsbody55 »

Stratocruiser2 wrote:
AviationAtWar wrote:Does engine/airframe time accumulate in real time or the accelerated time?
I just looked at the pilots hours and didn't notice the engine/airframe time. I will check that on the next transoceanic flight I make and let you know, if someone hasn't given you an answer in the interim.

Bill

It's been my experience with other A2A planes that accelerated time does not affect engine/airframe time. If you fly for an hour at X4, you will only put 1 hour on your airframe time. Haven't tried this yet in the Connie so I can't say for sure, but I'm guessing it won't accrue on airframe time.


Cheers,
Mike
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Stratocruiser2
Senior Airman
Posts: 160
Joined: 14 Feb 2016, 06:35
Location: Wales

Re: Pitfalls of accelerated time

Post by Stratocruiser2 »

spesimen wrote:
i can confirm that i have seen this. the first time i tried 4x, i would get a spike every 5 seconds or so where the manifold pressure and rpm would redline and then drop back to the original value.

however it is not 100% reproducible. i tried it again just now, and it seems to be working smoothly at 4x. i have no idea what is different between the two situations, unfortunately. i had been sticking to 2x and hadn't tried it since the first time, until i happened across this thread...

edit: one possible difference is that i'm not in career mode at the moment, i will give 4x a try when it is turned on during the next flight

cheers
-andy crosby
You are correct Andy, it is not 100% reproducible, but on my flights I guess the redline MP/RPM spikes occurred during approximately 75% of the 4x segments that I flew. I was in career mode during most of this time apart from one flight (where I accidentally hit the slew key shortly after take off from Bermuda!) but I am pretty sure that the bad spikes also occurred when using 4x during this non-career mode flight.

I will to do a few test flights in accelerated time with various settings turned on or off to see if I can identify any pattern to the occurrence of these spikes.

Bill

Have just done a test flight where I flew in normal time and also in 2x and 4x accelerated mode, flying either manually or using the autopilot. Although I didn't manually fly in accelerated mode for more than a few minutes each in 2x and 4x (as the Connie difficult to trim for level flight while in accelerated mode) the spiking issue didn't occur at all. However when the autopilot was in use the spiking started to occur after just a few minutes in 4x mode. With other aircraft I have sometimes noticed that they can pitch up and down while in the faster accelerated modes, which I think is probably the autopilot chasing the assigned altitude but I have never noticed power fluctuations except in some modern airliners with autothrottle enabled. Clearly the autothrottle as a cause does not however apply to the Connie!

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