DCS Mustang Developer Notes

[DDSSTT]

Hot air balloons heat up the air inside the balloon and the result is an air less dense then the air outside which makes the balloon lighter then air. this causes the lighter balloon to float on the heavyer outside air.

[Echo38]

Hot air balloons heat up the air inside the balloon and the result is an air less dense then the air outside which makes the balloon lighter then air. this causes the lighter balloon to float on the heavyer outside air.

 

Yes--this is what I was saying. Heating a gas expands it, so wouldn't cooling a gas contract it, reversing the process? And if cooling a gas compresses it, then why wouldn't compressing the gas cool it, reversing the process?

[DDSSTT]

I pretty sure it has to do with the confined space. Example, Hot Air Balloon, the gas is allowed to expand and exit the top hole in the balloon but as with the supercharger it is confined to a small space. This is forcing atoms to get packed tighter and tighter which I think is were you get your heat. the friction between the atoms as they want to expand away from each other.

[Yo-Yo]

How? I thought that compressing matter (in any state) causes it to become colder, not hotter. No?

 

Did you ever pump a bicycle tire?

[Nate--IRL--]

Yes--this is what I was saying. Heating a gas expands it, so wouldn't cooling a gas contract it, reversing the process? And if cooling a gas compresses it, then why wouldn't compressing the gas cool it, reversing the process?

 

Contract =/= compress.

 

Nate

[WildBillKelsoe]

You have that backwards - expanding a gas cools it - compressing a gas heats it up.

 

Nate

 

OK, lads, science class..

 

 

Compressing a gas makes its particles come closer together in confined space. Think of it as compressing rice, so, more contact between particles, more friction, more kinetic energy produced, and more heat generated.

 

expanding a gas has the opposite effect, because the particles are getting further away from eachother, less friction, more space to traverse freely without bumping into eachother that often with compression, and hence less thermal.

 

Even if you rub your hands together on a cold night out, you'd generate heat that warms you up, because each finger and palm (gas particles) are coming together in contact, and the gas in between is being compressed as you rub, so that is heat from compression.

[Echo38]

I pretty sure it has to do with the confined space. Example, Hot Air Balloon, the gas is allowed to expand and exit the top hole in the balloon but as with the supercharger it is confined to a small space. This is forcing atoms to get packed tighter and tighter which I think is were you get your heat. the friction between the atoms as they want to expand away from each other.

 

Contract =/= compress.

 

Ah, okay. I think I get it now. Sort of. ; ) Thanks, gentlemen.

[Echo38]

Oh! I've had an epiphany--it has to do with putting energy into the system. I wish I had thought of that earlier; it would have saved me a lot of puzzling. If you have to put energy into the system, either to expand it or to compress it, then it heats up--this makes perfect sense. (Now why didn't they just say so on all of the science-y web sites I visited trying to figure this out?)

[sam777777]

Oh! I've had an epiphany--it has to do with putting energy into the system. I wish I had thought of that earlier; it would have saved me a lot of puzzling. If you have to put energy into the system, either to expand it or to compress it, then it heats up--this makes perfect sense. (Now why didn't they just say so on all of the science-y web sites I visited trying to figure this out?)

 

That's correct, the expansion of the gas is to negate the input of energy into the system, much like how an equilibrium reaction in chemistry favours the side that negates any input into the system (Le Chatelier's Principle).

[Yo-Yo]

[leafer]

Turn this into a full-blown WWII sim and take my money again already!

[Double_D]

Turn this into a full-blown WWII sim

 

Great Idea...:thumbup:

[Echo38]

I like that idea, as long as each aircraft remains fully detailed. I'd be very disappointed if it ended up being a less-than-realistic survey sim like Flaming Cliffs, with the aircraft not being fully modelled, and the systems & engine management simplified. The world has enough low-detail survey sim-games. But if Eagle Dynamics were to make a full-blown WWII sim in which each aircraft (added individually over time) were as detailed as the P-51D, then that'd be the best thing I can imagine to happen to the P.C. flight sim world.

Edited September 21, 2012 by Echo38

[MACADEMIC]

I like that idea, as long as each aircraft remains fully detailed. I'd be very disappointed if it ended up being a less-than-realistic survey sim like Flaming Cliffs, with the aircraft not being fully modelled, and the systems & engine management simplified. The world has enough low-detail survey sim-games. But if Eagle Dynamics were to make a full-blown WWII sim in which each aircraft (added individually over time) were as detailed as the P-51D, then that'd be the best thing I can imagine to happen to the P.C. flight sim world.

 

+1!

 

MAC

[VIMANAMAN]

RE Yo-Yo's vid...

 

Nice!

 

I haven't played with this yet but that's a nice demo. I Like the parabolic dive (?) / low/no G start, and then demonstrating how you need some G to extend, and a further couple of manoeuvres to lock.

 

I read an account of a contemporary 51 pilot with a gear emergency and how he was helped by another more experienced 51 pilot by radio. It took the emergency pilot about 20 minutes of increasingly aggressive side slips to get both locked.

 

I'll have to try this.

 

Cheers

[VIMANAMAN]

Full blown WWii sim!!

 

That would just blow everything else away!

 

I won't hold my breath, but here's another +1 hoping!

[Static]

+1

Yes! Please! IL2 COD does not work with Windows 8, so far everything else works fine. A replacement is much needed.

[Wolf Rider]

OK, lads, science class..

 

Compressing a gas makes its particles come closer together in confined space. Think of it as compressing rice, so, more contact between particles, more friction, more kinetic energy produced, and more heat generated.

 

 

and the heat created is blown off thereby making the compressed gas colder... repeat the process a few times and you get liquid nitrogen/ oxygen, CO₂, etc

 

 

expanding a gas has the opposite effect, because the particles are getting further away from eachother, less friction, more space to traverse freely without bumping into eachother that often with compression, and hence less thermal.

 

 

the expanding gas absorbs heat from its surrounding environment... cooling the nearby environment

 

 

Even if you rub your hands together on a cold night out, you'd generate heat that warms you up, because each finger and palm (gas particles) are coming together in contact, and the gas in between is being compressed as you rub, so that is heat from compression.

 

rubbing two sticks together to create a fire, gets you warmer :) and a just as red glowing shoulder as pumping a bicycle tyre does

 

 

:book:

Edited November 19, 2012 by Wolf Rider

[sobek]

Compressing a gas makes its particles come closer together in confined space. Think of it as compressing rice, so, more contact between particles, more friction, more kinetic energy produced, and more heat generated.

 

Ouch, sorry for being such a smartass but that hurts just too much. ;)

 

Temperature in a gas can be explained as the mean kinetic energy of particles if you subtract coordinated particle movement, not the amount of particles "rubbing" against each other. Collisions between particles are ideal (unless they form a chemical bond or a different element or energy is dissipated in the form of radiation), that means kinetic energy is not transformed.

 

The reason why a gas gets hotter when you compress it is that in the process of compression, you increase the mean kinetic energy of particles.

 

Heat and temperature are different things, btw.

[ATAG_Snapper]

+1

Yes! Please! IL2 COD does not work with Windows 8, so far everything else works fine. A replacement is much needed.

 

Good news, Static:

 

 

http://forum.1cpublishing.eu/showthread.php?t=36078

 

Good luck!

[Blarney]

I would love to see more Developer Notes like this thread started with. I was asking a few questions about Manifold Pressure vs Engine Speed and I think an article about it in this thread would be really useful. Yo-yo and a few others chimed in and were very helpful in pointing out that the propeller changes pitch (and therefore pushes more air) to maintain engine speed. Would be great to see a full write up on the topic.

 

Other ideas might be to talk about limitations of the P-51D, what to avoid, and what to take advantage of. I've been watching some of the Dogfights series on YouTube where they interview actual P-51D pilots. They talk about special maneuvers like 'pull the stick into your gut, give full bottom rudder, then push the stick forward to recover'. Discussion on this kind of stuff would be great too. I really enjoy listening to these guys talk about how they actually flew the aircraft beyond what the Army gave direction to.

 

Talking about this stuff might be useful for Yo-yo too so he can improve his sim design in case we discover something that you can do in the sim that would be impossible in real life.

[Der_Fred]

Would it be possible to have a 'bug' thread.

 

I posted a question for the few P51 pilots and an aviation forum:

This is more of a comparison/question between Flight Sims (DCS) and reality, which I hopefully like to clarify ?

With the DCS P51 I'd set the speed to around 250 mph and then at the same time, pull full on elevator and apply full right rudder.

Knowing that this application is contrary to propwash and torque, at that speed I'd still expect to go into an accelerated stall, if not, a full spin to the right.

 

Would this assumption (and physical conditions) be correct ?

 

The reply

If you apply full controls as described above, the aircraft will enter a flick-roll, and most probably break apart. In something like a P51, it will be sheer madness to do this at anything above about 150 KIAS.

 

Flick maneuvers are limited to 110 KIAS in the Harvard/T6.

[159th_Viper]

Would it be possible to have a 'bug' thread.

 

I posted a question....

 

What exactly is the perceived bug? That the aircraft is not going into an accelerated stall to the right?

[sobek]

Would it be possible to have a 'bug' thread.

 

See attached picture.

[159th_Viper]

Would it be possible to have a 'bug' thread.

 

I posted a question for the few P51 pilots and an aviation forum:

 

This is more of a comparison/question between Flight Sims (DCS) and reality, which I hopefully like to clarify ?

With the DCS P51 I'd set the speed to around 250 mph and then at the same time, pull full on elevator and apply full right rudder.

Knowing that this application is contrary to propwash and torque, at that speed I'd still expect to go into an accelerated stall, if not, a full spin to the right.

 

Would this assumption (and physical conditions) be correct ?

 

 

 

In furtherance to my above query, herewith vid of what happens when I do what you said, ie full elevator/full right rudder at 250mph:

 

D6OJLH6Hd18

 

Track: Mustang stall.trk

 

Would appreciate it if you would point out in the vid what should not be happening/how it should be happening so I can investigate further.

 

Ta

Edited March 24, 2013 by 159th_Viper