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adlabs6
03-06-2004, 10:24 AM
Did they fix that wierd effect where you chop the throttle, and the thrust seems to keep on coming until you also chop the prop pitch? Do the planes as a group seem to lose energy faster now with no thrust (I mean engine idle, not off)?

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adlabs6
03-06-2004, 10:24 AM
Did they fix that wierd effect where you chop the throttle, and the thrust seems to keep on coming until you also chop the prop pitch? Do the planes as a group seem to lose energy faster now with no thrust (I mean engine idle, not off)?

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Gibbage1
03-06-2004, 10:29 AM
Its not the throttle. Its the constant speed props. Even though you chop the throttle, the prop pitch will automatically lower to try and keep the engine at the same RPM. You WILL decelerate, but there is not much fritchion. If you wish to decelerate faster, change the prop pitch, and go into combat flaps. If you want more, do some S turns. Or just fly the P-38L with the dive recovery brakes. Those help a lot http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif

Gib

VMF-214_HaVoK
03-06-2004, 10:34 AM
If you fly US planes just touch the rudder or do a roll and you will lose plenty of speed http://ubbxforums.ubi.com/images/smiley/16x16_smiley-wink.gif

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adlabs6
03-06-2004, 10:52 AM
So it's unchanged. Thanks for answering.

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tsisqua
03-06-2004, 10:59 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by adlabs6:
So it's unchanged. Thanks for answering.
<HR></BLOCKQUOTE>

Yup, its still correct, darn it all!

adlabs6
03-06-2004, 11:07 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by tsisqua:
Yup, its still correct, darn it all!<HR></BLOCKQUOTE>

Hi Tsisqua, I hope I wasn't misunderstood? It's not the RPM I was wondering about, but the deceleration when closing to idle. Maybe I didn't say it clear enough.

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BuzzU
03-06-2004, 11:14 AM
You'll notice the AI will roll to slow down while flying in formation sometimes.


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HarryVoyager
03-06-2004, 11:21 AM
Incorrect.

With a constant speed prop, if the engine is not providing enough energy to keep the prop turning at the specified speed, then the engery is being ganked from the airflow around the aircraft, which produces tremendous drag when the engine is idled at full fine pitch.

That's why twin props have their props set to go full super course/feather if the pitch governor fails. If they went full fine, they would cause a drag spike that could potentially put the aircraft into a spin.

Now, singles, on the other hand, go full fine, because the assumption is, if the engine isn't producing enough power to push the prop, you're going down anyways, so it's better to send the prop to a state where it is capable of generating controllable power.

Short summary:
Fine pitch==highest drag, but lowest torque on the engine.
Course pitch==lowest drag, but highest torque on the engine.

Harry Voyager

BfHeFwMe
03-06-2004, 11:24 AM
What's your VVI doing as you pull throttle back. You pull it back you have a trim change that's going to angle the nose down, expect to retain your speed. Try doing a slight upward pitch or at least hold altitude, do a bank turn with wings about 30 degrees bank angle without any elevator once your power is chopped, than see if you still want to complain about lack of bleed.

I can cross the middle of the runway at 600Kph, chop power, using only the bank will allow me to drop flap and gear before turning base on final. By the time I've turned 270 degrees, down to 180 Kph, bleeds just fine with good nose control.

I notice most flyers don't control AoA on approach, they ride it straight in nose down and fast. You simply can't do such a thing unless you've already dumped the speed in advance and already have established good nose AoA control. Your never going to dump it with nose down and hot.

TooCooL34
03-06-2004, 11:30 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by HarryVoyager:
Incorrect.

With a constant speed prop, if the engine is not providing enough energy to keep the prop turning at the specified speed, then the engery is being ganked from the airflow around the aircraft, which produces tremendous drag when the engine is idled at full fine pitch.

That's why twin props have their props set to go full super course/feather if the pitch governor fails. If they went full fine, they would cause a drag spike that could potentially put the aircraft into a spin.

Now, singles, on the other hand, go full fine, because the assumption is, if the engine isn't producing enough power to push the prop, you're going down anyways, so it's better to send the prop to a state where it is capable of generating controllable power.

Short summary:
Fine pitch==highest drag, but lowest torque on the engine.
Course pitch==lowest drag, but highest torque on the engine.

Harry Voyager<HR></BLOCKQUOTE>
Incorrect incorrect.
When you idle your engine, pitch already went to coarse pitch state to keep up rpm setting.
You're assuming you're controlling pitch manually in CSP.


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ucanfly
03-06-2004, 11:38 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by TooCooL34:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by HarryVoyager:
Incorrect.

With a constant speed prop, if the engine is not providing enough energy to keep the prop turning at the specified speed, then the engery is being ganked from the airflow around the aircraft, which produces tremendous drag when the engine is idled at full fine pitch.

That's why twin props have their props set to go full super course/feather if the pitch governor fails. If they went full fine, they would cause a drag spike that could potentially put the aircraft into a spin.

Now, singles, on the other hand, go full fine, because the assumption is, if the engine isn't producing enough power to push the prop, you're going down anyways, so it's better to send the prop to a state where it is capable of generating controllable power.

Short summary:
Fine pitch==highest drag, but lowest torque on the engine.
Course pitch==lowest drag, but highest torque on the engine.

Harry Voyager<HR></BLOCKQUOTE>
Incorrect incorrect.
When you idle your engine, pitch already went to coarse pitch state to keep up rpm setting.
You're assuming you're controlling pitch manually in CSP.


=815=TooCooL34 in =815=Squad, South Korea<HR></BLOCKQUOTE>

Hmmm I think I disagree with this disagreement. IF your at idle the CSP governer tries to go to as fine a pitch as possible to keep the RPM setting until it run out of prop pitch. AT that point it become a fix pitched prop. This has the effect of lowering RPMs when in idle and not diving or not going very fast. I find it hard to explain how you can maintain 3000 RPM in a CSP plane at idle below 180 mph for as long as it does in the game. Physics appears to be violated.

tsisqua
03-06-2004, 11:42 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by adlabs6:
Hi Tsisqua, I hope I wasn't misunderstood? It's not the RPM I was wondering about, but the deceleration when closing to idle. Maybe I didn't say it clear enough.<HR></BLOCKQUOTE>

My apologies, then for seeming to be a smart-a$$. I should have read better, because so many on here think that their A/C is going faster because of the sound that the engine makes, without actually looking at the air speed. At 100%, the plane will decelerate better than at say, 85%. The sounds that are made, as well as the indicated rpm, may or may not be modelled corectly, and since I don't know too much about constant speed props (I've only flown fixed pitch in R/L), I will leave you to the guys that do. My apologies again, Mate.

Tsisqua

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HarryVoyager
03-06-2004, 11:46 AM
Linkies: http://www.avweb.com/news/columns/182082-1.html

tsisqua
03-06-2004, 12:10 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by HarryVoyager:
Linkies: http://www.avweb.com/news/columns/182082-1.html<HR></BLOCKQUOTE>

This is a great site, Harry. I've read it, still need to read it about 5 more times, so I bookmarked it. Thanks.

Tsisqua

adlabs6
03-06-2004, 01:52 PM
Hey, no worries Tsisqua. http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif Like you say, I think the engine sound played maybe doesn't tell us much.

BfHeFwMe: When I was doing this I was constanly retrimming to retain altitude. My intention was to reduce airspeed from 350 or so for landing approach, while remaining on a straight in course.

Let me say this... I was playing around with this some more, and I may have found my failing. I was expecting more nose down activity at idle throttle, and in FB it seems that I can retain altitude from bleeding speed by raising the nose (maybe 5-8 degrees?) above the horizon. What had eluded me before, was that the sink rate was ever increasing, despite my trimming efforts. When I deliberately pull the nose (via stick) up above the horizon (again, looked between 5 to 10 degrees), I can stop the sink, and speed bleeds off a more quickly.

So, it would seem that my expectation from past sim experience was that a nose down action would be the result of idle throttle, and that airspeed would remain (near) constant in that case (descending, control speed with pitch). In FB, I was observing the nose remaining near level in many cases, and the airspeed not dropping fast at all. The missing link was the sink rate, which is apparently counting as a gain of speed due to decent, regardless of even a slight nose up attitude.

Maybe the plane I flew before didn't have a rate of climb dial? I can't remember now. I think that's what's up.

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WarGod5475
03-06-2004, 02:36 PM
hey the planes do seem to slow down alot better ... landings are way eaisier. you dont have to line up 5 miles out just to have a in the grass on the other end of the runway landing. lol
i used to hate that.
dont know ifits the props flaps or what but you can slow down when you need to.

TX-EcoDragon
03-06-2004, 02:40 PM
Adlabs: While in their clean configuration the aircraft were and are in the sim very clean and as such take some work to slow down, especially while descending. This is however true of the full scale aircraft as well. When slowed and placed in the landing configuration the increase in drag may be a little less than what is accurate, but it is slight. I tend to use the forward slip on most all of my approaches, and this seems to provide me with more than enough descent rate at a given speed. In the df environment I imagine this is how all pilots would have flown their approach anyway, to get on the ground from combat altitudes quickly(increasing descent rate without an associated increase in airspeed). Most aircraft (even slow, draggy, fowler flap equipped fixed gear, Cessna 172s) are flown into the airport environment at pattern alt of ~1,000 feet/305 meters above ground when as far as 4 miles away, and then configured and slowed before further descent. Fly in on a straight in approach and you will need a shallow flight path (usually 3.00 degrees in the modern world) and a slow airspeed to touch down at the point specified.

Slow most anything in the sim down to 200-180 kmh or below at a short distance out, and the descent rate can't be faulted.

Regarding some of the statements about constant speed props: Because engine oil pressure drives the pitch of the prop, and it must be sufficiently high to do its job, pulling idle power (and a few hundred rpm above it) will take the prop out of governing range and it will move to its highest RPM setting in singles, and in most basic twins (without pilot intervention or an automatic system in the twins equipped with feathering). This will result in an increase in RPM when pulling the power back though the increase in drag is pronounced in many aircraft. With these clarifications the info HarryV posted is right on.

S!
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BfHeFwMe
03-06-2004, 11:17 PM
Yup, your on the path for working great tactical approaches and those lovely sinking slow three point landings with AoA nose control.

Couple of things you can experement with, engine compression is modeled to a degree, but the effect is very small, so you don't notice it with the sink rate and speed too high. Try holding your altitude AoA slightly positive, chop throttle and pitch, than let your RPM's bottom all the way out. Once you hit bottom at idle, roll pitch back in. You can shave off 50 Kph very quickly in a Mustang, thats enough to get you down to safe flap deployment and gear speeds.

Combine it all with a 30 degree constant bank and you'll need to add some power on the threshold, going to slow you that efficient and quick.