Tutorial/Manual Q's |
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BeaverDriver
Check-In Staff Joined: 09 Jun 2010 Location: Canada Points: 33 |
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Posted: 11 May 2015 at 12:54pm |
I worked through the tutorial flight for the F27, then printed out the checklist from the manual (did real the manual first, of course) and I have a couple of questions please.
The tutorial tells you to takeoff at 16,500 rpm and then climb at 16,000 rpm if I remember correctly. However, in the manual/checklist, it says to climb at 14,200 rpm at 180 KIAS. Now, looking at the rpm gauges in the aircraft (if I'm reading them correctly - please see down), even at full throttle I can't obtain 16,000 rpm, (I can get to about 15,500 or so), but if I do go even that high, it feels like I'm handling a Lear with climb rates exceeding 4000 fpm at 3/4 full gross. So if I back off to 14,200, I'm still climbing like a banshee, but also the rpm's are well into the red arc on the gauge. I'm wondering if the numbers in the tutorial and checklists are correct? Now on the rpm gauges themselves, I assume the inside row of numbers is read from the shorter needle which are the thousands of rpm's, and the outside row of numbers are the hundreds values as read from the longer of the two needles. Am I correct in that? If you look at the screenie in the link below (I'm linking rather than pasting as the screenshot is rather large), I'm interpreting this rpm as about 12,720. Am I correct in that? http://www.glenndavy.com/private/FSX/F27Panel1.jpg If so, you'll notice that I am still climbing at about 2700 fpm through 10,000 ft at 180 kts, and with a 3/4 full gross load. That seems extraordinarily high for this airplane. Having a set of aircraft manuals sure would have helped with this by the way. So, can someone please confirm the tutorial/checklist numbers for me? I can't see being allowed to cruise with the rpm's in the red except perhaps for a short time at takeoff. Incidentally, if you use the colour bands on the tach's as a guide and ignore the actual numbers, then you do get a realistic performance envelope. Thanks for your time. Glenn |
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Glenn
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snave
First Officer Joined: 30 Oct 2011 Location: Southampton-ish Points: 351 |
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Remember these are generic engines - the 100 and 200 models differed only by engine version, while the 300 was equipped with different engines, among other changes.
Can't explain your over performance issues as not seeing that here (2,700 fpm is an immediate `slow to stall` scenario unless the climb rate is lowered) have you checked weight and balance? But yes, that image shows approx 12,700 rpm.
`Proper` engine data can be found here: Clearly, there is no combination that approves 16,000 rpm. 15,000 is the max, which would also make 14,200 as max continuous seem far more reasonable. Possibly the manual is a typo.
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BeaverDriver
Check-In Staff Joined: 09 Jun 2010 Location: Canada Points: 33 |
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Thanks for this snave. That link helps a whole bunch! Anyway, this does answer a few questions, like the "rocket-ship" performance to some degree, although I am still way over performing at 12,700 rpm which is an acceptable engine parameter, albeit near the very top of the green. My C of G and weights were well within the envelope, although were the C of G to be out, the aircraft would be less controllable and give you worse performance, not better (at least that's how it works in RL - who knows in FS!). I'll watch the engine settings a bit referencing the charts in that link and see where I end up, and also double check my weights as possibly (as you suggested) I emptied the airplane by accident and really was flying with no weight.
Thanks again for this and especially for the link. Great info to have! |
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Glenn
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snave
First Officer Joined: 30 Oct 2011 Location: Southampton-ish Points: 351 |
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I think this is something that will be looked at for the path, as it's tied into the operation of the A/P.
The only non-reported issue that I'm having is a `decay` problem in engine rpms after they've matched to throttle position, but I think that may be a problem with calibration at my end. Not going to make a point of it until after the Service Pack is issued.
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BeaverDriver
Check-In Staff Joined: 09 Jun 2010 Location: Canada Points: 33 |
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Well, might be. I was hand flying at the time, but it was a stable state (I had this attitude and power setting for several minutes. I'm still thinking they may have got their power numbers mixed up in the tutorial and manual, and when you use the correct numbers, it works out quite well.
You've seen that as well (the decay) have you? Most turboprops seems to suffer from this, but it's more noticeable (I think) given the high resolution of the tach's (that 100's needle can move a lot for not a lot of real difference, compared with modern gauges). But for sure I've seen it too, if that helps. |
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Glenn
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dbcooper
Check-In Staff Joined: 06 Dec 2014 Points: 11 |
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Glad you mentioned this Glenn. Seems the tutorial, RPM's listed in the manual on page 60 for climb and cruise numbers and numbers on the gauges don't match up for any version. I'm not having any odd performance issues as long as I operate the RPM's in the green, it seems fairly close to "by the book" at least according to the very limited information I've been able to find. But there are conflicts with engine data, performance.
Snave, thanks for posting that document, nice reference material. |
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MoPlanes
Check-In Staff Joined: 06 May 2015 Points: 19 |
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There seem to be some erratic behaviour as far as the engine performance for sure. I did a test and wrote down all the numbers from SL to FL250, but as I was finnishing off writing, suddenly the browser refreshed itself and whiped out everything.
Another anomaly was that on the ground, standing on the brakes, I got 15300 RPM but as soon as I let go of the brakes it suddenly dropped to 14600 RPM (if I remember correctly) or was it perhaps 14700? Anyway, that's a loss of around 500 RPM just for releasing the brakes. Make's me think something's wrong with the engine performance table in the air file. I suspect it look's like a rollercoaster instead of a steady curve ;)
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BeaverDriver
Check-In Staff Joined: 09 Jun 2010 Location: Canada Points: 33 |
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OK, so I just finished a flight and I watched the tach's pretty closely on this one. Yup, mine are all over the place as well. Not at all sure what's going on with this, but losing 500+ rpm on the takeoff roll is pretty disconcerting, even though it's not much against the total rpm's. However, there are some problems here with the engines, and what we've been told to use.
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Glenn
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Tupolev114
Check-In Staff Joined: 12 May 2015 Points: 4 |
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Now i am taking a bit of a stab in the dark here due to the unique operation of the RR Darts but a loss of 500 RPM from a full power standing start is not a concern its a legit thing it happens, now be that as it may on a typical engine like on the 182 a 500RPM loss is a lot and i would be worried but in an engine running up to 15000+ RPM on a good day 500 rpm is small change. It is a loss because of inefficiencies in the prop when speed is increased that for a time it will need to catch up by changing the blade angle so as to maintain the same RPM and from a full power standing start this will be more pronounced than is you were to slowly increase power and speed at the same time. i would not be supprised that if once up to speed the RPM was back at the 15000+ range again which would make the above true
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BeaverDriver
Check-In Staff Joined: 09 Jun 2010 Location: Canada Points: 33 |
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That's a very good point Tupolev114. Five hundred rpm out of 15K isn't really very much. I think the problem I'm having is that it's erratic throughout the climb, even once the aircraft is stabilized in the climb much like what MoPlanes found. Yes, there will be some deviation, but this seems a bit excessive. However, not ever having been in one of these planes or having a decent video to go by, I can't categorically state that this behaviour is incorrect.
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Glenn
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