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Why don't our warbirds cough and struggle on startup?


Nealius

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Whenever I watch real-world videos of old warbirds being started up, the prop cranks on the starter for about 5 seconds, then it sputters and coughs for another 4~5 seconds before running at idle RPM.

 

Contrast to DCS in the Mustang, Spitfire, Kufurst, Anton, and Thunderbolt, we get 1~2 seconds of starter crank, one or two coughs, then the engine instantaneously starts to ~1000+ RPM.

 

It's kinda strange having the engine start almost instantaneously. What's the deal?

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If you go to an event like Oshkosh where some of the absolute best maintained warbirds show up, there's very little "struggle" to get any of them started.

 

Couple two or three blades maybe and they come to life.

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Neither Merlin here "coughs" on startup - you can just hear some throttle adjustment on the startboard start:

 

 

Here's a possibly over-primed spitfire start. No coughing, just a little low RPM:

 

 

P-51, nothing really here either apart from a single exhaust pop - also seems like from an rpm/ throttle drop

 

 

Even after 17 years idle this one (Griffon engine) 3:20 starts without "couging" and spluttering.

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That first P-51 startup is slow like what I'm talking about. In DCS I've never had a Mustang start that slowly. I hit the starter, one or two prop turns and I open the mixture lever, and it's instantaneously running at 1000rpm or so instead of slowly accelerating to that rpm.

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Neither Merlin here "coughs" on startup

 

Here's the thing, he does have a point however. And I'd say these videos aren't even examples, jut exceptions. Engines do have some trouble on startup. In a general search you'd find roughly half do, in various ways.

 

There is something wrong with our Merlins in DCS, they lack dynamics. You can not only consistently, without fail, blindfolded and muted start the engine first try, then immediately firewall the engine. It won't stall, damaged, strain, or any adverse effects. There is no need to have the throttle cracked to startup in DCS...it means nothing to do it. Irl, if you pull that throttle back too far you risk the engine stalling. Not so in DCS. Additionally the engine will try to fire off even if the magnetos are off. We can't even wait for six blades to go by, because even with the ignition off, the engine will try to fire. And when shutting down, it happens again. Even with mags off, as you creep the throttle forwards as the RPM falls below iirc roughly 1200, the engine will continue to sputter for a long time until you've opened the throttle wide. And if it's wide anyways, it'll still try to turn over with the mags and fuel cut.

 

Merlins lack dynamics in DCS;

They're too consistent

Don't allow for some variants of the startup and shutdown procedures

Don't change depending on conditions

Invulnerable to negligence

 

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Here's the thing, he does have a point however. And I'd say these videos aren't even examples, jut exceptions. Engines do have some trouble on startup. In a general search you'd find roughly half do, in various ways.

 

There is something wrong with our Merlins in DCS, they lack dynamics. You can not only consistently, without fail, blindfolded and muted start the engine first try, then immediately firewall the engine. It won't stall, damaged, strain, or any adverse effects. There is no need to have the throttle cracked to startup in DCS...it means nothing to do it. Irl, if you pull that throttle back too far you risk the engine stalling. Not so in DCS. Additionally the engine will try to fire off even if the magnetos are off. We can't even wait for six blades to go by, because even with the ignition off, the engine will try to fire. And when shutting down, it happens again. Even with mags off, as you creep the throttle forwards as the RPM falls below iirc roughly 1200, the engine will continue to sputter for a long time until you've opened the throttle wide. And if it's wide anyways, it'll still try to turn over with the mags and fuel cut.

 

Merlins lack dynamics in DCS;

They're too consistent

Don't allow for some variants of the startup and shutdown procedures

Don't change depending on conditions

Invulnerable to negligence

 

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My stumbling, awkward view on this, as I think you are right . . . but . . .

 

Awhile back, Nineline poked fun at me (taken in stride) as I tongue in cheek requested that the new X-Ray damage model be applied to buildings and trees!!! He sent me a GIF of a PC catching on fire, which is accurate.

 

Engines, especially WWII engines, modeled to take into account ambient temperature, humidity, ambient temps of engine fluids and fuels, to do things like condensation of fuel in manifold intake runners, varying venturi performance based on temps, fuel density etc. Leaky piston rings, varying cylinder compression based on wear and tear. Cold crank reaction based on cold oil, and weak batteries etc. would pretty much cause the same thing . . . your PC to catch on fire.

 

While I too enjoy (and have routinely witnessed cold engine starts of all kinds) watching old cranks struggle and spit and sputter, I have a feeling the fluid dynamics, and all the other computational modeling that would have to be generated in real time to replicate this, would require a server farm capable of running at teraflops.

 

Just my layman's guess as to why it would probably be far too difficult to implement. But I also ask for the X-ray damage system to be applied to trees . . . so there is that to consider.

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Not my video, but I keep it like lot of other because they often get deleted from youtube.

Turn down the volume. And look the start up of this one ^^

 

Always impressive those flames coming from the engine.


Edited by JG13~Wulf
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  • ED Team
Cold crank reaction based on cold oil, and weak batteries etc. would pretty much cause the same thing . . . your PC to catch on fire.

 

 

You already have it without smoke from your computer.

 

And you always have mint fresh engine that in RL starts from the first flash in a cylinder.

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You already have it without smoke from your computer.

 

And you always have mint fresh engine that in RL starts from the first flash in a cylinder.

 

Even better, a good day to be wrong!

 

Also, I love those factory fresh engine starts, nothing more harmonious than the R2800 firing cleanly every time.

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I can add that most of the modern warbirds sits in hangars for months with oil sprayed into cylinders to prevent oxidizing.

But if you looks at warbirds run almost every day starts up are very clean and nice.

But must disagree here with yo-yo, Freshly build engine will smoke a lot, if assembled properly with pre oiling every part including cylinder liners, pistons, piston rings, valves, supercharger internal parts etc etc, it will smoke a lot at beggining.

I think our warbirds have new engines but with 10-20 minutes fly tests done before assigning to units.


Edited by grafspee

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You already have it without smoke from your computer.

 

And you always have mint fresh engine that in RL starts from the first flash in a cylinder.

 

Tlaking of this, is in the futur, a option to set the "age" of the plane is something you (ED) think about ? Not something that is necessarry. But could have some interest in campaigns.

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Although I admit certain engine startup dynamics would be a "nice to have" aspect, I don't think it is essential in combat sim (especially given the results of recent thread about auto-startup players vs manual-startup players), and I recall reading ED developers' comments on the subject in the same spirit in the past.

 

It belongs in civil flight sims (like in Accusim products with their persistent wear modelling), but there are more glaring omissions in DCS right now that need to be taken care of to make it a viable warbird competitor for 1C offerings.

 

Besides, such a dynamics aspect would have to be based on random numbers generator somewhere in the code, and we know that would render replay tracks recording impossible by definition. At least now the tracks do actually work every now and then ;) and that is a more important factor for me.

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You already have it without smoke from your computer.

 

 

 

And you always have mint fresh engine that in RL starts from the first flash in a cylinder.

Even with magnetos off? Before giving us a chance to count this six blades before turning the mags on?

 

Or not stall from the throttle being too retarded while cold (a feature btw Art-J, which even in a combat sim, in this particular sim I'd consider an important factor as immersion has always been a big selling point for DCS). Not any troubles at all when the engine is immediately firewalled 2 seconds after started?

 

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Tlaking of this, is in the futur, a option to set the "age" of the plane is something you (ED) think about ? Not something that is necessarry. But could have some interest in campaigns.

 

Maybe one day if A2A build an aircraft for DCS?

 


Edited by David OC

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Speaking of funky engine behaviour, ive recently flown some hours in a 1936 rearwin sportster 8500 with an 85hp 5 cylinder leblonde radial engine, what works on somedays dont work on others with regards to starting it up, thats for an engine that is soon to be 90 years old.

 

for shutdown simple things like idling it 100rpm too low can actually let the engine turn over with the mag switch off.

 

point is all engines are different, even those that are of the same type, there are many factors that can affect how an engine performs be it mechanical or environmental, i for one would love a very complex engine system for realisms sake but knowing what is real now is like comparing apples to oranges.

 

a lot of the aircraft in service are flown regularly and properly maintained and repaired after damage from combat, it is my experiance that an engine that makes it past a certain amount of hours will almost always continue to run for hundreds if not thousands of hours to come if properly maintained and regularly started. much in the same way a car engine would.

 

my experiance only being around 110 hours ppl with 5 in a tigermoth, 5 in a supercub and about 30 in the Rearwin. That being said a lot of the people i have flown with and spoken to operate aircraft that still use the original engine castings much in the same way that the rearwin is.

 

that being said for a sim its a balanance between cooking someones computer and having as much realism as you please. being a combat sim i would like to see enhanced damage models first for hostile fire.

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Tlaking of this, is in the futur, a option to set the "age" of the plane is something you (ED) think about ? Not something that is necessarry. But could have some interest in campaigns.

 

The Mi-8 has an engine age/wear/efficiency (forgot the official term) slider in the Mission Editor. I'm sure they could do something similar for the warbirds. The lower the slider, the more prop turns and coughing it takes to get started.

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Because it's assumed it's 1944 and our engines are well maintained, frequently flown (albeit not yet worn out) engines, that aren't hangar queens maintained by part timers with varying levels of DIY experience.

 

It's not perfect, I'm sure, and there are always going to be niggling flaws and imperfections, but as with Wikipedia, Youtube videos are only useful as a starting point not necessarily indicative of the full picture (see props, afterburner at night, etc etc, what you see and what the camera sees, etc)

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Even with magnetos off? Before giving us a chance to count this six blades before turning the mags on?

 

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Why you want count six blades before turning mags on, in the first place.

I don't get this part at all?

Not mention, that it is not possible in war time P-51.

Engine was cranked manually by ground crew before start, and starter button in p-51 is at the same time booster coil switch which will provide high voltage to ignition distributors.

But you can do it in Spitfire there is separate button for booster there so you can count 6 blades in Spity.

Pls show me this part mentioned in P-51 manual or P-51 pilot's notes, where pilot is supposed to count 6 blades.


Edited by grafspee

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Why you want count six blades before turning mags on, in the first place.

I don't get this part at all?

Not mention, that it is not possible in war time P-51.

Engine was cranked manually by ground crew before start, and starter button in p-51 is at the same time booster coil switch which will provide high voltage to ignition distributors.

But you can do it in Spitfire there is separate button for booster there so you can count 6 blades in Spity.

Pls show me this part mentioned in P-51 manual or P-51 pilot's notes, where pilot is supposed to count 6 blades.

The revised 1954 (AN-01-60JE-1 to a different T.O. 1F-51D-1)and 1957 (T.O. 1F-51D-1) flight manuals. It is performed this way in A2A's P51 familiarization video.

It is also said so in ED's own manual on pg. 127

Iirc this is a small way of prolonging the engine's life, by letting the engine rotate a few times and get oil around. Particularly when ground crew isn't available to rotate the prop by hand, like in our case.

 

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Edited by Magic Zach

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The revised 1954 (AN-01-60JE-1 to a different T.O. 1F-51D-1)and 1957 (T.O. 1F-51D-1) flight manuals. It is performed this way in A2A's P51 familiarization video.

It is also said so in ED's own manual on pg. 127

Iirc this is a small way of prolonging the engine's life, by letting the engine rotate a few times and get oil around. Particularly when ground crew isn't available to rotate the prop by hand, like in our case.

 

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Like i said, second world war time p-51 had no option for that.

While starting engine, it has too low rpm to get proper pressure in oil system. Sometimes it takes couple of seconds to get oil pressure after engine start up when rpm are much higher. This counting blades is more like safety against hydro lock. 1.5 crank revolution supposed to deliver oil to engine before start ?? I some how don't believe in this.

What you need to extend engine life time is electric oil pump.

A2A recreated modern p-51 which are flying now, not 1945 war time warbirds.

I will agree with other things , like throttle response when engine is cold, what to good imho.

Other thing which i don't like about p-51 start up that you have to do everything in order if not engine wont start.

For example, when you forget to prime engine, priming while cranking engine is not working, but in RL you for sure can do something like that.


Edited by grafspee

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Like i said, second world war time p-51 had no option for that.

 

Why not

 

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Why not

 

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Because starter button is hot wired with booster coil, unless you dont prime engine you will fire it up once you hit starter button. Looks like in modern p-51 magneto switch is cutting off booster coil as well.

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Awhile back, Nineline poked fun at me (taken in stride) as I tongue in cheek requested that the new X-Ray damage model be applied to buildings and trees!!! He sent me a GIF of a PC catching on fire, which is accurate. [/Quote]

 

I remember that post, but that is then limitation in DCS engine instead limitation in physics modeling.

 

It would not need be perfect, just a simulation. You add each tree a few break points depending their size. Like flying an aluminium made WW2 plane on 600 year old oak and the plane squeezes as a tin can under foot. Make it a F-14 kind and it will cut few trees by it mass, especially from upper proportion.

 

Having example 3-5 cut lines on tree and make the upper part of trunk to fall on direction of impact force and you have wanted effect.

It doesn't need to be dynamic or similar manner full physics calculations but just neatly animated cut and fall.

 

And it needs to be done only for trees that are near aircraft and on the way of flight path to be activated, otherwise just for weapons as bombs that put few trees fall away from explosion point.

 

Engines, especially WWII engines, modeled to take into account ambient temperature, humidity, ambient temps of engine fluids and fuels, to do things like condensation of fuel in manifold intake runners, varying venturi performance based on temps, fuel density etc. Leaky piston rings, varying cylinder compression based on wear and tear. Cold crank reaction based on cold oil, and weak batteries etc. would pretty much cause the same thing . . . your PC to catch on fire. [/Quote]

 

Again not required. We are talking about just a random effect now and then. Just add some sound effects, some smoke effects and propeller start-up problem effects.

then just randomly add them to happen.

 

It is after all just now and then when player needs to start engine second or third time.

 

There is no requirement to model and emulate engine in atomic level for that. That is just unrealistic expectations already that what DCS does now at level it does it.

 

When it is random, you can take just some common causing factors to increase it's likelihood. Like if you have too high mixture it happens very likely. Or if you have cold engine (first start) or if you have couple other variants then it has higher change to happen once or twice.

 

It is nothing more than a effect that is ran. Just like now with jets that you can have a turbine stall and need to do an air start. Need to have that proper RPM and proper throttle position and off you go....

 

It just adds the feeling that engine has that starting problem here and then and everything is not so perfect.

 

Like we do not need to have bugs modeled to have dirty windshields, or model FOD by modeling small rocks or something....

After all it is about simulation, not about emulation. So you can just add the random effects without emulating why such effect happens.

 

To simulate things, one doesn't need to know what happens inside a black box when it is known something else can happen.

 

Just a Random Number Generator is performed, known as "roll a dice" that did an engine just have a one or two problematic start-ups. What does it cost? Couple repress a button to start engine?

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I remember that post, but that is then limitation in DCS engine instead limitation in physics modeling.

 

It would not need be perfect, just a simulation. You add each tree a few break points depending their size. Like flying an aluminium made WW2 plane on 600 year old oak and the plane squeezes as a tin can under foot. Make it a F-14 kind and it will cut few trees by it mass, especially from upper proportion.

 

Having example 3-5 cut lines on tree and make the upper part of trunk to fall on direction of impact force and you have wanted effect.

It doesn't need to be dynamic or similar manner full physics calculations but just neatly animated cut and fall.

 

And it needs to be done only for trees that are near aircraft and on the way of flight path to be activated, otherwise just for weapons as bombs that put few trees fall away from explosion point.

 

 

Again not required. We are talking about just a random effect now and then. Just add some sound effects, some smoke effects and propeller start-up problem effects.

then just randomly add them to happen.

 

. . .

 

Just a Random Number Generator is performed, known as "roll a dice" that did an engine just have a one or two problematic start-ups. What does it cost? Couple repress a button to start engine?

 

Appreciate your insight and responses . . . but I am just a layman, so I will leave this to the experts. I am not the one that can weigh in on applicability, or feasibility.

 

If these things are possible, wonderful! After all, I still get a smile when I strap on an airplane, and see the needles swing in response to my actions, a very happy consumer here.

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