Aces High Bulletin Board
General Forums => Aces High General Discussion => Topic started by: ALF on February 11, 2004, 10:47:05 PM
-
Im really not sure I understand the purpose?
In AH1 I never bother with RPM....cause it doesnt seem to do anything that the throttle doesnt do....am I missing some key game feature....since beta 1 no less:eek:
The engine going more or less silent is freaky!
-
rpm now does what it should very well.
big fuel savigns at low rpm and throttle settings
-
RPM = revolutions per minute, Not decible or volume per minute....
:)
It is very odd...I agree....even in a car your engine doesn't get quite when you reduce power. It's does loose some volume - guestimating around 6db, but it doesnt have the severe lose of volume as currently the case with new patch. A step in the right direction - guess you could say "right street - wrong address"
Imagine it would be hard to sync audible revolutions of the engine to correspond with throttle changes in the game..not sure - leave that stuff to the programmers...lol
But - Engine sounds should be more of "half-way doppler effect" Oscilating up with pitch as power applied (some volume) and decresing pitch as throttle released (with slight decrease in volume). Hopefully not to much pitch increase as to where the planes sound like ricers on a saturday night at taco bell.....
A prop plane flying at 1000ft is about 88 decibles - about as loud as a garbage diposal. I'm guessing due to proximity - that would equate to roughly 92-98db in cockpit. A jet flying at 1000ft is around 102 dbs. Currently if full power in AH is set to roughly 98dbs - when you throttle back, it sounds as if it drops 45 decibles to 53db - almost to the sound of a dish washer in comparison. It seems that it should only drop a quarter of that or less. (10-12db from full power to off)
-
Cars are insulated, tuned piped, mufflered, & catilytic convertered, & exit 12 feet behind the driver.
Airplanes are big growly radial engines with NO pipes, NO mufflers ohh & they exit within a few feet in front of the cockpit.
Ya think maybe they'd sound a bit diff?
Start up your lawnblower or snow mower.
Play with the throttle up & down. Hear the difference?
-
stop flying ur lawnboy ghost :)
-
Still a lawn mower doesn't have as much of a decible decrease with power as the throttle does with patch 13.
Currently as is - the throttle sounds like a volume control....not controling RPMs
-
On the positive side, you can now hear your engines overreving than the set amount during powerful dives. It's really cool!
-
I race cars. A racecar has no mufflers etc..... just like a WWII fighter.
There is a HUGE difference in noise at different rpms. At idle the car is really not that loud. At 3k rpm its much louder... just starting to cause babies to cry. At WFU 8000 rpm.... small children are in a panic, wives are screaming for help and red blooded men have a grin from ear to ear.
It sounds like speaker volume should be adjusted. Make it normal at idle, pretty lound at cruise and so loud your wife is pitching a fit at full throttle. That will be closer to realistic.
Fang
-
Not sure of all "racing" rules, but for eveyones benifit.....
If you've been to a sanctioned track, most have decible regulations on the cars. The rules that I found were that the nosie level / exhaust from the car can be no more that 96 db at 100 feet. Which roughly equates to being withing 5 feet of a lawn mower
I guess this is about SPL(sound pressure level) or "intensity" of the sound. When a engine is on idle - the engine is still emitting a certain db per "stroke" or "revolution". As the throttle is apllied, the revolutions increase and so does the frequency(time) that an indivual "stroke" db is produced. When you're at 200Rpm it will seem quiter than when you're at 3000rpm due to the fact that you have 3000 individual "stroke" decibles crammed into a minute rather than 200 "stoke" decibles.
Basically, If you shoot one round off in a gun - it's loud, but not that loud as compared to 3000 rounds firing off in one minute. Where as 3000 rounds being fired will pale in comparision to 8000 rounds in a minute.
What i'm getting at is a "percieved" loudness. The guns are all firing at the same db, just the frequency of fire makes it seem louder.
Granted there are other factors involved, coupling for one will make an engine running at a certain RPM seem lounder as well as amount of fuel burned per stroke.
-
I agree with waffle. The volume should change a bit but its the frequency that should be the dramatically tied to our throttles.
Very nicley put waffle, i was thumbing through my dust covered physics book looking for some equatiion describing a combustion engine operation when I got down to your post. Another analogy, is dipping your hand in hot water for 1 second then out for 1 second is completely different from dipping it in for 10 seconds, thenout for 1 second, even tho the water temp does not change.
-
The volume should change a bit but its the frequency that should be the dramatically tied to our throttles.
Why?
The momentary throttle up/down is not going to effect anything with an engine equipped with a CSU prop. The characteristic sounds and noises each engines makes is determined by its internal structure and engine revolutions, no?
If cutting the throttle drags the plane down to a really notieably slower speed, and thus, to a level where the CSU cannot compensate and hold the designated RPMs, it's then it should start revving down, isn't it?? :confused:
-
I always thought throttling down reduced volume because less fuel is being pumped into each cylinder per revolution, thus there is a less powerful combustion and hence less noise. It's not the prop blades whizzing through the air that makes most of the racket, it's the thousands of controlled explosions happening a few feet in front of you. ;)
-
ok - one more example....
Take remote control planes or gas powered R/C cars.....
When you're piloting them - you can hear your engine just fine at a slow speed...the engine emits a lower frequency audio pitch at a slower cycle. When throttle is applied the audio pitch increases as the engine cycles increase. But, there is very little audio difference in Sound pressure levels, or decibles. Some, but not as much as one would think.
pls note pitch here is related to acoustics, not aerodynamics.
I'm trying to clarify the engine volume thing - not worried about props cutting through air and other noise created by prop driven aircraft.
-
seems like it gets too quiet when you throttle back..
-
cc Waffle, I think people more or less agree that the engine becomes to quiet when throttled back. The "sound pitch linked to RPM" part, I don't see any problem.
In FB, the engine does become a little less loud when throttled back, and emits a low pitch 'chugging' sort of growl when left to idel. It's definately not 'silent'.
-
What if, Im flying a B-17 at high altitude and want to slow down abit (IAS) Do I use the rpm or manifold setting?
When I want to save fuel. Do I leave the manifold at the normal cruise speed? (in a B-17 about 35) and reduce the rpm's?
-
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
Kweassa you are right.
You guys have to remember the variable pitch props, otherwise you sound like ......
-
Originally posted by Waffle BAS
ok - one more example....
Take remote control planes or gas powered R/C cars.....
When you're piloting them - you can hear your engine just fine at a slow speed...the engine emits a lower frequency audio pitch at a slower cycle. When throttle is applied the audio pitch increases as the engine cycles increase. But, there is very little audio difference in Sound pressure levels, or decibles. Some, but not as much as one would think.
pls note pitch here is related to acoustics, not aerodynamics.
I'm trying to clarify the engine volume thing - not worried about props cutting through air and other noise created by prop driven aircraft.
I understand what you're saying, and for the most part, I totally agree with your theory. But, there are some considerations that you may be over looking which could slitely alter your view.
Adding to your theory, you almost have to consider more then one engine type and model. And for game files your gonna have to find a real tight compromise if you are truly going for accuracy. Theatrics would be a flipside.
All engine types run different, while still functioning around the same fuel engine thoery.
Let me try to use a car engine here for an example. Most American made cars would fall directly under your theory. However, there are other models which perform differently. An engine will have different audio effects if you instantly crush the throttle to nothing, verses a gradual deceleration. If you instantly reduce fuel input the engine is still at a high rpm and will suck air back and cause, in some cases, a popping, much the same way a Harley would. In a gradual deceleration the RPMS are slowing matching the fuel intake, therefore you do not get such a radical effect. My BMW is louder at a low RPMs, with lower tones (sometimes as low as say,..40hz), it resonates my house when I can barely even hear it run. The engine groans on acceleration, pitch climbs rapidly. Then suddenly, as the engine RPMs go over a certain point past 3000 (or as I hit 70 mph) the engine goes completely quiet, even while still accelerating. When I decelerate quickly the audio of the engine comes to life again. Most American cars, on acceleration, will turn into a higher (almost jet like) pitched whine and continue to climb. So we have different effects depending on the engine model or type. This is where you need to really dig into individual engine characteristics to be accurate.
This would most likely lead to HTC having to set each planes’ response to individual settings, and maybe sound files. I would think it would be extremely tiring research alone to do this. It’s almost a science in itself to get total correctness for the game. Higher quality files allowing a wider sound spectrum would include higher and/or lower tones\frequencies to help achieve this goal. So the sound file has to be correct for the combination of file and coding to be accurate. This is why I would think that instead of a global setting for audio it would fall into an individual engine model concept. I highly doubt HTC, much less any other sim, is going to tackle this, but I may be wrong about that.
Now throw into the equation that each plane was insulated, or not.
You HAVE to include prop noise because it does add to volume\pitch as well. Depending on the plane engine and prop design, I some times hear the prop more.]
So while I agree with where you are going with this, I also add my own personal views into the same theory.
-
Ok - lets do this....take your engine out of the plane...Take of the
prop.. mount it to whatever the hell you would mount it to to test it....
Fire it up - How loud is it? Full throttle? Idle?
Lets start here and get this sound in the ball park first.
then we can worry about prop noise. Those should be on a seperate file shouldn't they since they are not tied with engine noise :)
BTW - what are the commands to increase / decrease prop pitch...did I miss something on day 4 of ah training?
-
I am not smart enough for the physics debate club, but for whatever reason, in real life I do not get a similar audible experience riding in real life aircraft as is currently implemented in Beta 13 and I think that should be the real point.
-
> Lets start here and get this sound in the ball park first. Then
> we can worry about prop noise.
Sound good to me.
> Those should be on a seperate file shouldn't they since they are
> not tied with engine noise :)
Absolutely
-
I have a nice cockpit recording of a 109G-2 with DB605 from start up, take-off, flight and landing. (test flight of a restored warbird). I wish AH (or any flightsim) could reproduce engine sound like this, it's awesome.
It's a 12 meg mp3 file. If anyone can host the file for me, I'll be happy to share it. :)
-
We are all in danger of getting too technical here.
I think most of us when we open up the throttle want to hear a sound to remove our fillings and one that sounds like a warbird at an airshow doing a highspeed pass.
When the throttle is at idle it should sound like same warbird on a slow approach put-putting and coughing to touchdown.
Now all of this is seperate and distinct from the engine management fuel economy etc (which btw i think is a good idea).
Basically when fly a virtual Spitfire I want it to sound like virtually every Spitfire I have ever seen and heard ie when you push the loud lever (throttle) it sounds "Big and brash" and when you pull it back to idle its not quiet but "small and polite".
I know there are many reading this that will say ahh but in real life thats not how it should be . That may be so but also in real life we ordinary mortals have a perception of how things should be (all engines should sound like a V8 , all women should have a perfect figure, all men should be hung like a horse et al) so I imagine most of us here will agree that a warbird should sound like a warbird whether its right or wrong.
I think I can see what Pyro was trying to do but it just doesnt work for me.
Adjuster
-
Well, the mp3 I've got sounds exactly right ... because it is exactly right. ;) And by listening to it you will understand how the engine sounds when applying power, changing revs, increasing speed (wind noise) etc.
-
give it to me sholz I will host it. Do you know how to sftp?
erg
-
I know what FTP is but SFTP?
-
Originally posted by Ghosth
Cars are insulated, tuned piped, mufflered, & catilytic convertered, & exit 12 feet behind the driver.
Airplanes are big growly radial engines with NO pipes, NO mufflers ohh & they exit within a few feet in front of the cockpit.
Ya think maybe they'd sound a bit diff?
Start up your lawnblower or snow mower.
Play with the throttle up & down. Hear the difference?
Another oddity is that there is no increase in engine song when engaging WEP. If manifold pressure increases, HP increases, if HP increases there is a corresponding increase in exhaust volume. When I would switch on ADI and push up the boost to my R-2800s (C-118 has four of them, C-131 has two), there was a marked increase in engine volume.
And, what's the story with this unstable taxi nonsense? Don't these guys realize that most aircraft had lockable tail wheels and tricycle types had nosewheel centering devices? I've taxied quite a few aircraft, including several tail draggers and I've never seen anything like the constant swinging in AH2.
My regards,
Widewing
-
I'd like to hear that sound file too GScholz. Get it hosted asap :)
-
Originally posted by ergRTC
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
throttle is not tied to rpm
Kweassa you are right.
You guys have to remember the variable pitch props, otherwise you sound like ......
Sure it is...we don't have turboprops.
With engine running on the runway, set pitch to fine, pull the throttle to idle, What happens to RPM?
It drops.....
It should drop when windmilling too, but it really doesn't. It stays at max rpm with the engine off, until about 100 mph and below, where it then drops just 500 rpm... needs some work.
In any US fighter, to decrease speed, you first pull back the throttle, then adjust rpm. This prevents overboosting. To increase speed, you adjust the rpm up and then add throttle. Again, this prevents overboosting. When at military power, you decrease rpm via pitch, you will get an increase in boost. It doesn't work like that in AH2. If you pull off rpm in AH2, you get a decrease in boost... that is backwards. In the real world, pulling off rpm at max power via pitch would so severely overboost the motor as to do damage within seconds.
I also was unable to get the P-51's RPM below 2,000 rpm. We should be able to get all power settings as they appear on the P-51. Likewise, same problem for the P-38L. The Flight Operation Instruction Chart for the P-38L shows 1,600 rpm at 28 in/Hg (MAP) for most economical cruise... I can't get close to that.
If modeled correctly, engine blowups would be common until people learn that throttle IS tied to rpm ......
Picture some guy cruising along at 2,100 rpm, 34 in/Hg MAP... He spots the enemy boring in and rams the throttle up to max power.... Blam goes the motor!
What he should have done is first push up the rpm, then advance the throttle. Later aircraft like the P-51, P-38 and Fw 190s had a automatic throttle/prop control, which increased rpm according to throttle position.. Older aircraft did not have this feature and many late war aircraft didn't have it either.
This is how it should work in AH2 if realism is important.
Having a couple of thousand hours behind R-2800s and R-1830s, I've seen more than my share of overboosted (and sometimes damaged) engines from careless engine management.
Adding engine management is a good thing... getting it right is even better. I suggest that the guys at HTC get their hands on a few pilot's and NATOPS manuals and review the basic relationship between rpm and throttle in these aircraft.
My regards,
Widewing
-
I also was unable to get the P-51's RPM below 2,000 rpm. We should be able to get all power settings as they appear on the P-51. Likewise, same problem for the P-38L. The Flight Operation Instruction Chart for the P-38L shows 1,600 rpm at 28 in/Hg (MAP) for most economical cruise... I can't get close to that.
There's a P-38L in AH2? :rolleyes:
-
Originally posted by GScholz
I know what FTP is but SFTP?
Secure FTP (somthing like SSH File Transfer Protocol) using tuneling and encryption if I'm not complelty wrong :)
-
YEs it is secure ftp. When I get to the lab tomorrow I will set up a way for you to send me the file.
Widewing
1) I think the p51 wep is a bug, as I assume most people believe at this point.
2)Of course you are right about the boost and the over boost, I am only arguing against the silly idea most people have that increased throttle = increased rpms, and that increased throttle means altered pitch (of course under certain circumstances they do, pushing up from idle on the runway and the like).
As you know neither of these are correct IF ... all of the things that would keep you from blowing up your engine are accomplished by the game.
If your hub is altering your pitch to maintain constant rpm, as long as your giving it enough throttle the keep the prop turning, your rpm should remain constant.
----
Now, as for the unreal side of this, I am sure they are refining things like how the pressure responds to dropping rpm at constant throttle. HTC have said they dont want this to be overly complicated, so I assume engine blowouts due to mismanagement are not going to happen, although I wish they would....
as far as pilots, hitech owns a plane does he not?
erg
-
does anybody know how much more fuel mix is sucked into an cylinder with higher throttle settings? I cant imagine its THAT much more at high throttle than idle. I assume it has to be more, but i cant think mechanically of why? The suction is increased, but so is the frequency of the stroke. Most of the added fuel goes into firing more cylinders per unit of time.
I think a lwan mower should be a good example of the noise model here. its definatley more pitch oreinted than volume, imho.
-
Originally posted by WhiteHawk
does anybody know how much more fuel mix is sucked into an cylinder with higher throttle settings? I cant imagine its THAT much more at high throttle than idle. I assume it has to be more, but i cant think mechanically of why? The suction is increased, but so is the frequency of the stroke. Most of the added fuel goes into firing more cylinders per unit of time.
I think a lwan mower should be a good example of the noise model here. its definatley more pitch oreinted than volume, imho.
Typical for the Allison V-1710-89 as installed in the P-38L:
Power setting of 1,600 RPM @ 22 in/Hg consumes 46 gallons per hour.
Power setting of 3,000 RPM @ 54 in/Hg consumes 334 gallons per hour.
Not an insubstantial difference.... Little more than doubling the RPM and MAP results more than 7 times the fuel burn rate.
I think its a great idea for HTC to accurately model fuel burn rate and engine management.
Now, stand within 10 feet of a Packard Merlin at idle. It's loud but not painful. Do an engine run-up to 30 in/Hg and it gets painful. Go to full power (tail tied down, as well as chocked and tied down main mounts) and you better have hearing protection. It has nothing to do with the pitch of the sound, it's the huge increase in decibel level that causes the pain.
My regards,
Widewing
-
Originally posted by ergRTC
as far as pilots, hitech owns a plane does he not?
Yes, HiTech does own a sport plane, an RV8-A with tricycle gear if I'm not mistaking.
It is powered by a Lycoming with a Hartzel constant speed, two blade prop. It's a kit plane, and not one for someone with minimal mechanical skills either. They are highly regarded in the sport plane community. You can check out the various RV kits at Van's Aircraft (http://www.vansaircraft.com/)
My regards,
Widewing
-
Originally posted by Waffle BAS
Still a lawn mower doesn't have as much of a decible decrease with power as the throttle does with patch 13.
Currently as is - the throttle sounds like a volume control....not controling RPMs
Same thing here ...
-
Originally posted by Widewing
Typical for the Allison V-1710-89 as installed in the P-38L:
Now, stand within 10 feet of a Packard Merlin at idle. It's loud but not painful. Do an engine run-up to 30 in/Hg and it gets painful. Go to full power (tail tied down, as well as chocked and tied down main mounts) and you better have hearing protection. It has nothing to do with the pitch of the sound, it's the huge increase in decibel level that causes the pain.
My regards,
Widewing
Now this P38 has to be tied down, correct, so that means there's prop on it......how much of the decible increase is in prop noise??
I'm just tring to sus out the "engine" only noise..so lets take the engine out off the 38 and fire it.... no prop....
measure the dbs then....measure the pitch(audible) change in the engine only..as the throttle is increased. There will have to be a pitch change.....Increasing the throttle in in any engine will affect the pitch.
I hear planes land / take off now and then from the airport near here...only recently did I start listening.....
Now this is from the ground, so am I hearing prop noise or engine? - the plane was finishing taking off - and had a resonance off around 400hz...my guestimation. It cut power and leveled off.....the pitch(audible) dropped to near 300-320 HZ.
400hZ is a little lower than a standard A note on a guitar. "G" is about 315, i believe. It did not get softer, but stayed the same level Db wise....
So now this is PITCH (audio) change.. was it a prop, or the engine?
-
Thats It!
I'm going to the airport with a db meter, Real time frequency analyzer / oscilliscope and a 12 Pack! :D
-
It's funny, but I thought AH1 had it right. The volume of the engine didn't decrease so much, but reduce the prop rpm and the rpm of the engine decreased.
Current AH2 engine sounds are much like ww20l (a feature I didn't care much for), reducing throttle setting had no effect on engine rpm sounds. Yet switching from max rpm to economy rpm produced a reduction in engine rpm sound.
Don't think I care much for the present settings.
-
"Currently as is - the throttle sounds like a volume control....not controling RPMs"
I wish somebody with more of a clue than me could help clear up the throttle and rpm thing. In these planes throttle (while flying) does not = rpm. So saying something about high throttle and idle, or something about volume control not rpms leads to a unreal expectation of the behavior/sound.
Also, fuel consumption can be related to throttle position not just rpms, as in the example widewing gave us. Engines under load maintaining the same rpm as an engine not under load consumes much more gas. Example granny gear in a truck pulling something or an idling truck just sitting on the pavement.
-
Originally posted by Waffle BAS
Now this P38 has to be tied down, correct, so that means there's prop on it......how much of the decible increase is in prop noise??
I'm just tring to sus out the "engine" only noise..so lets take the engine out off the 38 and fire it.... no prop....
measure the dbs then....measure the pitch(audible) change in the engine only..as the throttle is increased. There will have to be a pitch change.....Increasing the throttle in in any engine will affect the pitch.
I hear planes land / take off now and then from the airport near here...only recently did I start listening.....
Now this is from the ground, so am I hearing prop noise or engine? - the plane was finishing taking off - and had a resonance off around 400hz...my guestimation. It cut power and leveled off.....the pitch(audible) dropped to near 300-320 HZ.
400hZ is a little lower than a standard A note on a guitar. "G" is about 315, i believe. It did not get softer, but stayed the same level Db wise....
So now this is PITCH (audio) change.. was it a prop, or the engine?
Let's keep this as simple as possible.
Decibels is a measurement of pressure.
Pitch is a measurement of frequency.
Regardless of the frequency, without an increase in pressure, there is no increase in "loudness".
As to the P-38, it's a poor plane to use for this type of analogy. Its exhaust is effectively muffled by the turbo installation. P-38s are surprisingly quiet. Likewise, the P-47 is less obstrusive than the F6F, despite having, essentially, the same powerplant.
On the other hand, the P-51D has short stacks that are in line with the open cockpit when on the ground. Exhaust noise is direct and very loud. Prop noise is substantially less than engine noise when on the ground. At high altitude, prop noise can be incredible when the prop tips go supersonic (remember that props have a spiral motion through the air, and tips going supersonic was/is common for a large diameter prop turning at max rpm, especially up high where the relative speed of sound is considerably lower than at sea level).
By the way, you wouldn't tie down the tail of a P-38 for a high power run-up, it has a nose wheel. You may want to tie down the main mounts because it's probable that the brakes wouldn't hold and it might jump the chocks.
My regards,
Widewing
-
Correct decibles are a measurement of sound pressure levels...
Pitch has, in this thread, been misconstrued as prop pitch and frequency (audio). As i blieve RPM has been to horsepower
"Let's keep this as simple as possible.
Decibels is a measurement of pressure.
Pitch is a measurement of frequency.
Regardless of the frequency, without an increase in pressure, there is no increase in "loudness"."
What I am getting at is that the "Engine" only sound seems so very off in a SPL (decible) way right now.
Take the engine starting right now. It's fine until the sound jumps over to the "stock" engine .wav file.
If your throttle is off - It sounds like you engine drops out when the start cycle completes.
The very last 3/4 seconds of the engine start sound, sounds to me, what an engine at idle would sound like.
So in a perfect world, we'd have a idle engine with a nice low lope to it (or other engine characteristics depending on the engine).
Then as we increase the throttle to the engine, the frequency WOULD rise To the approrite sound of "X" engine at "Y" RPMS.
You cant fight physics... Audio frequency will always increase/decrease in proportion to how many RPMs the engine is putting out, as will exhaust noticiably change. A percieved loudness is due to the coupling / phase of exhaust...hence "tuned" pipes in autos and what not. There will also be a slight increse in Db as more power is applied due to the strength of the combustion and rate of combustion.
There are also many variable and different types of engines...
some resonate at different rpms differently...some RPM setting things will seem to "settle" out....when a harmonization occurs between Engine exhuast / RPMs / vibrations...
Think of when you're driving on a highway and there's a certain speed your car just "likes" It's seem quiter and smoother.
Like I said before - Engine only...let not take prop noise into account yet....
Thats another subject that should fall into place once the engine sound is hashed out.
hehe Widwing...glad you realized about the not tying the 38s tail down...got that from your first post....lol. hindsights always 20/20 i guess :) Actually - I miscontrued your previous post....lol you were talking about a merlin..I had allison on the head
-
Hmm, let me see if I can explain in written words what it is about this change in engine sound that bothers me.
It's like listening to a recording of an engine constantly running at high/mid rpm range. Then to simulate the engine returning to idle, the volume is simply reduced. No change in sound pitch, or the combustion detonation frequency.
It needs more work HiTech.
-
The faster the engine the higher the sound frequency.
The slower the engine the lower the sound frequency.
The bigger the "bang" in the cylinders the louder (bigger sound waves) the engine. (more fuel /higher manifold pressure)
The smaller the "bang" in the cylinders the quieter (smaller sound weaves) the engine. (less fuel lower manifold pressure)
Prop noise is speed and angle of attack to generate noise from air turbulance.
However air "slap" would be louder at higher AoA. Which would be permitted at higher manifold pressures.
As the prop rpm increases the frequency would increase.
Fundamentally the frequency increases with rpm but the volume should increase with manifold pressure................... which is a function of both throttle and rpm. (and additive)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Waffle I believe AH has always assumed that pitch control is automated as a function of RPM setting. Hence at a given rpm setting the prop pitch changes with every change inmanifold pressure to utiles the power available without changing rpm.
RPM can only be changed by the pilot once set the prop pitch changes to maintain it.
-
Tilt got the fundamentals down nicely. However I'd like to add that the mechanical noise of the engine is not reduced by reducing boost. The supercharger is linked to rpm and will whine just as much at low boost as at high boost, same with valve ticking, engine vibration and any other mechanical sound. The best way to recreate this would be to have two different sounds. One for the mechanical sounds that stay constant at a constant volume level regardless of boost, and one sound with the deep roar of the engine which gets lower with the reduction of boost. Both sounds change in frequency with rpm. A second way would be to only change the volume of the deeper tones (mid-bass tones) of the sound, while leaving the higher tones (typical of mechanical noise) at the same volume. A third/second sound of engine "sputtering" may be mixed in for low rpm and low boost levels.
My friend who runs the http://www.lordpanzer.com site has graciously agreed to host the 109G2 Cockpit recording for me.
In-Cockpit_flight_109G2.mp3 (http://www.lordpanzer.com/downloads/In-Cockpit_flight_109G2.mp3) (12 megs. Right-click - "Save as")
-
great clip - you could sample alot of that....
-
Originally posted by GScholz
The supercharger is linked to rpm and will whine just as much at low boost as at high boost,
Agreed the super charger would be a constant volume but will change in frequency with rpm...........
(except multi stage superchargers which are not "sound" modelled in AH so when it is switched in the engine model to the 2nd stage we do not hear it)
AS `said I agree the KISS approach would be to have a fixed back ground mech noise that varies in frequency with rpm then an exhaust note that varies in frequency with rpm and volume with manifold pressure.
Splutter could be used during the start up .wav and left there.
-
I think the 'mechanical' and 'combustion' sounds is an absolutely fantastic idea.
-
wherever this is going, I think AH1 "felt" better than the latest attempt in AH2
-
I'm sure you all know this but a constant speed prop alters the pitch or "bite" of the blade to maintain a constant rpm as needed when factors such as throttle (power) change. The pitch or frquency of the sound produced by the engine is tied directly it's rpm which is the same as the prop. Even though I've never flown a constant speed prop plane I suspect that HTC probably has this part right. What I find that doesn't feel right is how long the prop will spin at a high rpm once power is chopped completely.
-
http://www.microsoft.com/games/flightsimulator/fs2002_articles_machado_propeller.asp
Explains what is going on pretty good (does not address sound however)
Also of interest: http://www.wolf-aviation.org/aircraft_noise.htm
-
Wow - only 13 more post and we'll have as many post in this thread discussing engine sounds as there are supplying information to HTC that they requested in the sticky above this thread :)
-
Beta 14 is now available for download:
(Snip)
"Increased engine volume at idle setting"
Long threads sometimes are useful ...
:)