throttle versus rpm?

[TDeacon]

Anyone know why there are separate key commands for throttle and for rpm?  I would normally have assumed that rpm was a function of throttle (as in a car).

[TEShaw]

Let me jump right in because I don't really know.  I always assumed it was propellor pitch.

[talliven]

when flying an A/C with a constant speed prop, throttle controls Manafold pressure.  You have another control which controls RPM of the prop.  Very basic idea of how it works is:
The blade angle of the propeller  will adjust in flight to maintain a constant RPM, when you adjust the throttle you cause the engine to put more power into turning the propeller.  The engine will then cause the blade angle to increase to maintain the given RPM.  However this result in more thrust due to more bite from prop.  Normally if your gonna want fast response you want a high rpm, usually max for takeoff.  For long cruise you reduce the rpm for better fuel efficiency but you have more lag to produce full power when increasing throttle.

Keep in mind while on ground taxiing throttle will control rpm because the prop is already at lowest pitch and can no longer control rpm below a certain power setting.

hope that helps

[DamnedRen]

In this game you can set both manifold pressure and rpm. If you take a look at the E6B the next time your up you will see the best cruise settings. Set your manifoild pressure and rpm to the settings listed on the E6B then look at fuel economy, etc. Thats one main use for it. Here's another;

RPM will feather the prop and it will adjust your pitch. If you want to see it in action go up to 10k alt then shut of the engine. now push yer nose over til your doing 1k descent rate as noted on the Verticle Speed Indicator (VSI). .now push the minus (-) key on the keypad and you'll see the plane begin to accelerate. You are feathering the prop and you can actually reset your glide rate back to 1k descent and extend your actual glide path. Once you do that try hitting the plus (+) key and re-introduce drag and nose will with dip sharply due to the increased drag. Again you can adjust feather in glide to either extend or shorten your descent path. You might find this helpful if you've run outa gas and are trying to glide home.

Speaking of glide you might use this rule of thumb as a worst case scenario. Without doing any fancy number crunching if you know your not gonna make it home check your altitude and use 1000 feet for every mile you have to go to get home and you will probably make it. Here's why and it's all related to to that same question about RPM's you originally asked.

If you set a 1000 foot descent rate in glide and feather the prop, your airpseed will decay and then maintain around 120 mph. Ok, that = 2 miles in distance per minute or for every 1000 ft you've descended you traveled 2 miles. Unfortunately, we get sloppy in try trying to get the plane turned the right direction and then setting at maintaining 1k rate of descent so plan on figuring a loss of almost 1500 ft per 2 miles traveled. This is still pretty good if you use the old rule of thumb. If you gotta travel 10 miles to get home try and grab 10,000 ft of alt. Then if you make no mistakes you will appear over the field at 4k or so maybe a lil more. Not bad for going 10 miles with no gas and not having to ditch. We all know each sector (sqr on the map) is 25x25 miles so its pretty easy to judge your distance hme with in a mile. Remember to use 1k for each mile to go and you WILL make it home.

Hope this helps answer some of your question on the "why fors" of RPM.

Ren

[TequilaChaser]

to throttle up use the    =  Key (left side of backspace key)
to throttle down use the   - Key  (left side of backspace key)

to Full On Throttle use SHIFT =
for Full Off Throttle use SHIFT-

for rpm increase use KEYPAD +
for rpm decrease use KEYPAD -

default is rpm max at start up

for more info go here and read all sections

AH Help

I hope this helps........need anything more
you can reach me at TequilaChaser@flyaceshigh.com

geez Ren,
guess we was responding at same time  


my bad TDeacon, I read your why as being a where........

[TDeacon]

Thanks guys...

Now, what is E6B, and where is it described?     :-)

[TequilaChaser]

Originally posted by TDeacon
Thanks guys...

Now, what is E6B, and where is it described?     :-)

when in flight, look on the clipboard for  E6B  click it and a page will swing open to the left, and give you some great info for the particular plane you are in