Are engine temperature limits simulated?

[lwalter]

I did the following experiment:

- close oil radiator

- close engine cowling shutters

- set RPM and manifold pressure to max

After a while, cylinder head temperature goes over 300°C and oil temperature goes over 150°C.

That's what should happen.

However, I can continue flying for long time and nothing happen. No smoke, warning lights or any sign of engine failure.

Am I missing something here?

 

[StevanJ]

1 hour ago, lwalter said:

I did the following experiment:

- close oil radiator

- close engine cowling shutters

- set RPM and manifold pressure to max

After a while, cylinder head temperature goes over 300°C and oil temperature goes over 150°C.

That's what should happen.

However, I can continue flying for long time and nothing happen. No smoke, warning lights or any sign of engine failure.

Am I missing something here?

 

Heres the answer

[Northstar98]

2 hours ago, lwalter said:

I did the following experiment:

- close oil radiator

- close engine cowling shutters

- set RPM and manifold pressure to max

After a while, cylinder head temperature goes over 300°C and oil temperature goes over 150°C.

That's what should happen.

However, I can continue flying for long time and nothing happen. No smoke, warning lights or any sign of engine failure.

Am I missing something here?

 

I have had an engine stop on me but I was far below what you did.

 

The thing is the Yak-52 is the only asset in DCS to not have a damage model whatsoever (apart from really slamming it into the ground and exploding and maybe collapsing the gear), so there's that.

 

Unfortunately the only answer you're getting is "it's not abandoned but no timeframe".

[lwalter]

Thanks

I just realized by reading through the Yak 52 forum that it has been in early access for a long time.

I hope it's not completely abandonned, because it didn't take ED that long to implement better system modeling in the other WWII planes...

 

Edited October 3, 2021 by lwalter

[StevanJ]

3 hours ago, lwalter said:

Thanks

I just realized by reading through the Yak 52 forum that it has been in early access for a long time.

I hope it's not completely abandonned, because it didn't take ED that long to implement better system modeling in the other WWII planes...

 

 

 

You might be better off speaking to support.

[Callsign112]

23 hours ago, lwalter said:

Thanks

I just realized by reading through the Yak 52 forum that it has been in early access for a long time.

I hope it's not completely abandonned, because it didn't take ED that long to implement better system modeling in the other WWII planes...

 

 

Yes if you read through the forum, then you can tell there are still some outstanding issues with the Yak 52, but ED has repeatedly stated that they will be addressing outstanding issues/bugs after they get the Mosquito done. You are welcome to make a bug report if the issue has not already been reported, but hopefully you will see progress soon.

[lwalter]

On 10/3/2021 at 5:43 PM, StevanJ said:

 

You might be better off speaking to support.

 

As a general question, is there an official channel / tracker to report bugs to DCS? I thought this forum was the only place. I'd be happy to learn I missed that.

 

 

5 hours ago, Callsign112 said:

Yes if you read through the forum, then you can tell there are still some outstanding issues with the Yak 52, but ED has repeatedly stated that they will be addressing outstanding issues/bugs after they get the Mosquito done. You are welcome to make a bug report if the issue has not already been reported, but hopefully you will see progress soon.

 

I didn't know about that timeline: after Mosquito get done. Thanks  @Callsign112.

[StevanJ]

14 minutes ago, lwalter said:

 

As a general question, is there an official channel / tracker to report bugs to DCS? I thought this forum was the only place. I'd be happy to learn I missed that.

 

 

 

I didn't know about that timeline: after Mosquito get done. Thanks  @Callsign112.

Talking to support often gets you an answer thats unavailable here.
Use the search engine, to try and find the topic, if its unavailable or you cant find the problem, play a game, save the track straight after, and then post it to the bugs section with the headline as the bug that you wish to report, when its been reported youll get a stamp to say as such.
 

Edited October 4, 2021 by StevanJ

[Callsign112]

On 10/4/2021 at 1:14 PM, lwalter said:

 

As a general question, is there an official channel / tracker to report bugs to DCS? I thought this forum was the only place. I'd be happy to learn I missed that.

 

 

 

I didn't know about that timeline: after Mosquito get done. Thanks  @Callsign112.

Just to let you know, I think you are quite right in terms of what you saw with the Yak FM like numerous other people have reported. But have you seen this? Interesting video showing how good the Yak is at gliding.

 

 

[bbrz]

On 10/5/2021 at 11:24 PM, Callsign112 said:

Interesting video showing how good the Yak is at gliding.

The real one has a pretty bad L/D ratio of 7 in clean config at 160km/h.

With the gear and flaps down it decreases to 5.5.

Edited October 8, 2021 by bbrz

[Callsign112]

That is really good to know @bbrz. Did you watch the video linked to the comment you are quoting? If you do, you will see he spends a lot of time above 160, and he glides for about 40km. Not bad for an old girl with long legs. Are you suggesting that aerodynamic drag is not modeled in the DCS Yak 52, and can you tell how accurate the FM is by watching what happens to his altitude as he changes his AoA? Because I can't, but it sure looks real.

 

 

[Ramsay]

19 hours ago, Callsign112 said:

If you do, you will see he spends a lot of time above 160, and he glides for about 40km.

 

Best Glide Speed (Lift to Drag) is 160 km/h, so at higher speeds the increased drag *should* reduce the glide distance.

 

 

In the video the engine failed at approx. 4,000 m and was able to glide approx. 40 km.

 

• 4,000 m = 13,000 ft

• 40 km = 21.5 NMI

 

The expected glide distance = 5.5 NMI x 13/5 = 14.3 NMI = 26.5 km

 

So the glide distance in DCS was 50% further than expected (assuming negligible tail wind). 

Edited October 10, 2021 by Ramsay

[Ramsay]

Testing in Open Beta 2.7.6.13436, I'm seeing a glide distance of approx. 17 NM (32 km) which is 20% further than expected from the POH but not nearly as bad.

 

 

Perhaps the previously quoted 40km estimate was overly optimistic or something has changed since the video was made ?

[Callsign112]

7 hours ago, Ramsay said:

 

Best Glide Speed (Lift to Drag) is 160 km/h, so at higher speeds the increased drag *should* reduce the glide distance.

 

 

In the video the engine failed at approx. 4,000 m and was able to glide approx. 40 km.

 

• 4,000 m = 13,000 ft

• 40 km = 21.5 NMI

 

The expected glide distance = 5.5 NMI x 13/5 = 14.3 NMI = 26.5 km

 

So the glide distance in DCS was 50% further than expected (assuming negligible tail wind). 

 

 

1 hour ago, Ramsay said:

Testing in Open Beta 2.7.6.13436, I'm seeing a glide distance of approx. 17 NM (32 km) which is 20% further than expected from the POH but not nearly as bad.

 

 

Perhaps the previously quoted 40km estimate was overly optimistic or something has changed since the video was made ?

@Ramsay, thanks for your comments and for making the discussion a little more interesting.

 

Couple of things though. The approximate distance was based on the video authors recollection of the amount of time he was in the glide. So we can't really confirm the approximate distance, and your last statement would be better written as "might have been 50% further, since we seem to be on a path of splitting hairs here.

 

This was a casual conversation, and the point of interest for me was more that the author successfully lands his Vplane without power.

 

His speed also changes constantly, which makes it even more difficult to guess the distance. Then there is the issue of wind, and how the author had the simulator set up.

 

BTW how does air temperature play into things? The gliding example you provided, which I am assuming is referenced information for the Yak because I haven't looked it up myself, doesn't mention air temperature.

 

At times we see that he is well above 160. What happens to drag as speed increases?

 

But I think the biggest difference here is that you are using a referenced glide distance, while my guess was based on the amount of time aloft. Not really an apple to apples comparison here. I see now that my original guess was likely way over exaggerated. 

 

So to make a second attempt at guessing the glide distance, I had a closer look at the video and think I can improve my guess considerably. At about 17 seconds in the timeline, you see the edge of a river come into view on the left hand side of the plane. He is still in powered flight at this point. At about 38 seconds in the timeline, which is after the author makes an edit to the video, he loses power. Based on the same river section that we see multiple times in the video, and his approximate heading, I am guessing that he is somewhere over Tsutshvati about 17 NM out from his touchdown when he loses power.

 

I think some pilots might have even considered landing without the gear down in the same circumstances, but watching his AoA, speed, and the effects when he makes the error of momentarily lowering his flaps looks very real IMO.

 

So while there are no doubt still outstanding issues with the Yak 52 FM, ED has acknowledged this with a promise to fix. But I think in terms of what we are discussing here, we are grasping at straws if we want to insinuate that ED is incapable of accurately modeling resistance in their FM. I am also convinced that my original guess was way out, and that the real distance is pretty much spot on to what we would expect. I am looking forward to making the Yak my next prop. 

Edited October 10, 2021 by Callsign112

[Ramsay]

29 minutes ago, Callsign112 said:

What happens to drag as speed increases?

 

Parasitic drag increases,

 

 

AFAIK best glide is calculated at max. weight, so with less fuel, etc. the best glide speed would be slower, I did a zero fuel test as well but actually glided a slightly shorter distance than I had previously.

[Callsign112]

15 minutes ago, Ramsay said:

 

Parasitic drag increases,

 

 

AFAIK best glide is calculated at max. weight, so with less fuel, etc. the best glide speed would be slower, I did a zero fuel test as well but actually glided a slightly shorter distance than I had previously.

And do you see anything in the video that would suggest the model is reversed or doesn't represent this well? His speed and altitude seem to logically follow his AoA. In terms of the FM itself, it seems to be pretty close based on a closer look at the approximate distance. I had no idea my original guess would spark such an interesting discussion.

[Ramsay]

42 minutes ago, Callsign112 said:

And do you see anything in the video that would suggest the model is reversed or doesn't represent this well?

 

No, however the question is outside my expertise, AFAIK it's usually a matter of FM tuning rather than something missing, and I have to be guided by the feedback given by RL Yak-52 owners/pilots who say there are things that could/should be improved (but none of that matters if ED feel their time/resources are better used elsewhere).

 

For those who can, I suggest enjoying the DCS Yak-52 for what it is, rather than what it might have been.

Edited October 10, 2021 by Ramsay

[Nealius]

To answer the question: they seem to be working now. Oil still gets hot on an 11C day, but I'm able to keep it under 100 with the oil cooler full open. It used to peg at max, so that's an improvement.

Also you can very easily kill the engine by overcooling the cylinder heads. If the needle dips into the lower yellow section for just a few seconds your engine will seize.