Fun stuff, hu ?

I can't account for someone else's model's accuracy as far as performance goes.. but from my real 182 eperience, 22" of manifold pressure would be on the "economy" side of cruise settings. To get 145KTAS out of a 182 at say 3,000msl, you'd probably be looking at 24/2400, but that's from memory.

I'm sure you know the difference between indicate and true airspeed, so I'll only "hint" that  your 120 might have been indicated..  

What's neatly realistic about this, is that even though you took great care in planning, your actual experienced varied quite a bit.. keeps you on your toes to NEVER fly with exactly the amount of fuel you'd need  

As you do this more.. stuff will become instinctive.. BUT also like in real flying; as soon as you get complacent, something will bite you.. lol

Quick note:  VFR cruising altitudes are thousands plus 500. ( 0-179 = 3500, 5500, 7500, etc.) ( 180-359 = 4500, 6500, 8500, etc.)

IFR altitudes are the thousands..

Until you come across a true dilema, I'm gonna just observe. Sounds like you're more than on the right track..  

Edit.. ( my C177RG performs very close to realistic.. easy on FPS too, makes a good, complex aircraft trainer )

Thanks for the feedback guys!

Mobius - I guess you're right about the mountain, in VFR conditions it wouldn't be such a worry and of course you often see light aircraft flying quite close to such terrain features. Stupid question, but again I need to clarify - does flying VFR mean I can always ignore the approach plates to an airport and just enter the pattern about 1000 ft above airport elevation on the downwind leg and land (after announcing my intentions of course) dodging any obstructions I see etc. Or are there special VFR plates? Is using approach plates based on instrument approaches even allowed if you're filed VFR??

Well, if I do need to, or can at least choose to use approach plates during VFR I will use 5500 as a cruising height on the same trip to Iliamna...
...thanks Brett, forgot the rule. And - I forgot about true airspeed - d'oh!

The E6B emulator calculates 120 at 3000 as 127.200 ktas, so still nowhere near 145. But then the emulator wants me to put in MSL which I understood to be the real height above sea level. Is/can MSL mean pressure altitude instead, or density altitude?

Stern's book and newly-found common sense tells me that true airspeed should be based on density altitude i.e. pressure altitude corrected for non-standard pressures and temperatures.

http://www.flightsimbooks.com/flightsimhandbook/CHAPTER_02_23_Airspeed_Indicator...

So is the emulator oversimplifying or can MSL mean density altitude?

Well, the density altitude (3000ft, 14 degrees C (20 at sea level)0 was 3580 and if I put that into the emulator I get the exact same result as for 3000ft...127.200 ktas. Hmmm. Maybe at such low altitudes the difference between pressure altitude, real altitude and density altitude are not worth worrying about??   Unless there are extremes of temperature and you're higher up?? If so, any rough guidelines on what those extremes could be?

Brett, I will certainly try out your C177RG when I feel like a change from the 182 during September, which I plan to spend doing VFR flying with navaids so I can check what I'm doing and learn the ropes before moving towards 'serious' IFR navigation in October. The reasons why I'm using the Carenado 182 and not the default 172 as in your course are a. I've paid for it and want to use it b. it comes with detailed performance charts and c. the Flight Sim Handbook and other books here:

http://www.flightsimbooks.com/

are ancient books based on FS 1995 and they use the C182 which was the default bugsmasher at that time - as you probably know.  

Thanks a lot for your help so far... I'm looking forward to planning my next VFR tonight, and flying it tomorrow. Will report back  

Roger, over and out.

krigl wrote on Aug 25^th, 2008 at 8:57am:


You can shoot an IFR approach under VFR if you want, but generally you enter the pattern at the appropriate altitude as you described. If you want more realism, try to find the specific pattern altitude and pattern directions for the airport in question (it ain't always 1000 AGL and left-hand!).

Quote:

No. Density altitude is pressure altitude corrected for (nonstandard) temperature. MSL is based  on standard temperature (15 degrees Celsius).
Wait, you answer your own question below...

Quote:




Quote:


Only if temps are standard, from the surface to the high FLs.
For flying light aircraft, generally DA is not worth worrying about for the cruise profile- as Brett said, you shouldn't be calculating performance to the last drop of fuel.

Personally, for that kind of flying in the sim and RL, I only give a damn about my groundspeed while in cruise. Why fuss with calculating true airspeed when all you need to do is time your progress to determine groundspeed?
But density altitude  critical for takeoff and landing performance, so temps on the surface are an important factor... and under some conditions, time-to-climb numbers may be so affected by DA that you need to consider that for flight planning (like if you're taking a 150 up to 10,000 on a hot day, LOL).

Enroute, DA vs. pressure altitude can affect the altimeter setting, but of course one should be getting altimeter corrections from ATC or automated stations. I never use any calculation for that, other than the simple rule of "high to low, look out below" (as you pass from a high pressure area to a low pressure area, your true altitude will be lower than indicated... and vice-versa). Watching the weather, or knowing from a report or forecast what lies ahead, can help you at least watch out for misleading altimeter readings if you can't get an update on the radio. If it's critical, say on a flight over mountains in poor vis or at night, it could be wise to land somewhere and just set the altimeter to the field elevation there.

And one more aside: VFR cruise altitudes (odd/even thousands plus 500) start at 3000 AGL. So if you're flying over terrain that is 1000 MSL on average, you can fly any altitude you want up to 4000 MSL.

Great stuff guys, thanks a lot for your patience and time!!

So I won't be 'afraid' to practice IFR approaches at non-controlled airfields, and at controlled airports I should let the ATC vector me in. Stupid question again maybe, but what are approach plates and SIDS and STARS and so on for at controlled airports? In case the tower gets taken out by a meteorite?

3000 ft AGL is something which I missed! Not MSL! So if the mountains are at 10 000 then I can fly VFR up to 13 000 without worrying about odd and even thousands+500?? Wow. Well...doesn't that create conflicts with faster, heavier aircraft? Or other aircraft flying IFR in VFR conditions... My guess: a. the heavies are no problem in controlled airspace, and outside they are too high, and b. flying by IFR will be at 4000 AGL minimum... right?

I'm worrying about all the niggly details, pressure vs density altitude etc because I want to train my brain to deal with these things, and because I want eventually to progress to higher flying stuff...
Once I've got my head round basic flying I'm going to try VFR at 12 000 ft too to get a feel for it.


Brett_Henderson wrote on Aug 25^th, 2008 at 10:07am:


I think - course is the direction in which you are trying to go, heading is the direction your plane is actually facing while following that course, track is the 'path' your plane is following over the ground (ideally similar to the course), bearing is.... ah. Wait a minute. Erm. Dammit. Well... ...  ...  

I need to do some more reading methinks...

Alright Brett!  The SID/STAR explanation makes sense - keeping the airlines in place - and if I'm flying into a large controlled airport it's most realistic to just let ATC vector me in - though more interesting to ignore ATC and fly the whole approach myself and hope they let me land when I'm on final ...and that there's nothing on the runway...

I was trying to get to grips with approach plates before I decided to go back to square 1 and VFR. When explained it all makes sense - but looking at an approach plate with no explanation makes my head hurt...

I hope you will find time to do that instrument training course - the question is how many people need it. Hard to tell - everyone's like 'I flew my PMDG 747 from LA to Hong Kong last night' and you just don't know if they are really seriously simming the whole flight or just doing it 'seat of the pants' with GPS and taking screenshots - my usual approach.    And if they can't really 'fly' properly - do they want to learn? 

Anyway, I've got to get to grips with the basics before working through your VFR stuff, so I'm off to plan a flight now.

Cheers

Roger

Here comes another long, probably boring progress report - I've been away for a short break and bought a new gaming console, but had at least some time to thoroughly plan a flight between Homer and Iliamna, Alaska. I spent about 2 hours making the flight plan from scratch, trying to figure out what information I needed to put on it, and in what order, with help from the FS Handbook, SkyVector, E6B emulator and Carenado's performance guide.

I flew the Victor airway that heads west from Homer then doglegs (at Nosky) up to Iliamna. It was about 110 NM if I remember. There was what I think is called a fix (Walus) midway between Homer and the dogleg bit. I flew at 6500 as we were heading west, VFR, and the minimum altitude for the airway was 6000. I set up a nice crosswind for the first 2 thirds of the flight, then changed it and the visibility at Nosky dogleg.

Question - does the distance from Homer to the fix count as a 'leg' in flight planning? I had 3 legs - Homer to Walus fix, Walus to Nosky fix, Nosky to Iliamna. There was no change of direction at Walus.

For each flight I do I'm giving myself aims and checking my success.

Aim 1 - make a detailed flightplan and consider all variables. I was fairly successful there - I found there was little info I wanted that wasn't in it during the flight.

Aim 2 - calculate flightpath with magnetic and wind variation. Here I was not so successful and kept moving off course. If I hadn't referred regularly to my terrain map, and the in-sim map I would have got lost. I think I input the temperature at 2 degrees higher than I calculated for when setting up the flight, not sure if this would make a big difference. If I didn't make that mistake - looks like the perf. figures and the results of the E6B... or perhaps the simulator itself - can't be completely trusted for flying 'by the numbers'. I guess that, like in real life, the use of instruments to check your position regularly is very important for getting from A to B - and that's why VFR only pilots are not allowed to stray far from base, right?

Aim 3 - track outwards from Homer NDB, and at the dogleg Nosky, intercept the Iliamna NDB. On my first flight I failed to do this utterly, because the ADF just would not work! I tried doing it in FSX as well and it wouldn't work there either.    I was so frustrated! I tried other NDBs and couldn't get any joy there either, and not in the default C172 or my Aerosoft Twotter, and the explanation in the learning centre wasn't helpful either, especially as it seems to describe a slightly different set-up - for example there are not 2 frequencies that can be swapped like with the nav radios, but only one etc. There seems to be a button which if you press it the needle sits horizontal and does nothing. I thought I might have pressed it by mistake but I couldn't see it and in fact none of my ADF buttons responded... Very annoying. I went off and played Oblivion instead. On returning from a short holiday I tried again, and instant success - the ADF worked (!!) though the buttons still don't seem to...  

So I did the flight again, got the temp right, and saw a lot more fidelity between what I'd planned and what actually happened, though still got blown off course a bit - but checking the ADF, the terrain map and then the in-sim map (to see how I was doing) kept me closer to what I wanted. Fuel consumption turned out higher too than the previous flight and closer to my conservative planning estimate.

Next flight coming up - I'm going to repeat some short 'milk-run' hops in the Himalayas and see during planning and in-sim how height affects performance in the C182RG, flying from one place at 4100ft up to Lukla at 9 000ft -ish and back again, with different air temps and payloads. Then I'm going to repeat the same hops in the default C172 and see what happens there, and then try a Super Courier, or other STOL plane. I'm curious if I'll really see/feel a difference for each, and how much. I've never paid much attention to it before.

Question - The flight to Lukla will basically be ascent all the way. For calculations of fuel used etc should I take the average height we'll be at? Or split the short trip into several legs at different heights. Or would it be more sensible to stay out of the mountain valleys by circling at the home airport up to height and then flying a straight path to Lukla? It would certainly use more fuel - and be less fun...

Question - how does one go about seriously planning a flight in a plane you don't have the performance data for? Estimate, based on something similar that you do have data for, or know well? Rely on the FS in-sim planner? Such in-depth data as comes with my Carenado planes is very rarely seen.

If you've got this far - thanks for reading and have a good day!  

Any comments or question answers welcome...

Krigl

My reply here might be a little out of order... I'm answering in order of significance..lol  And I'm on my way out the door (been in Ohio this weekend)..

First..  It sounds like there was just some sort of NDB glitch the first time you tried this..  but it DOES point out a realistic aspect to simming. Had you been in the default C172.. I'll bet you'd have had no instrument problems. The fact that you're learning in a more complex airplane, and having mystrerious problems, is JUST TOO REALISTIC  

Now.. remember that NDB navigation with wind is tricky stuff... My lessons here in our forum cover it pretty well. I'll just point out that if you aren't well versed in it.. you can end up flying all over the place.. even an arcing spiral to/from and NDB.. because they don't use radials (like a VOR).. they just use a bearing relative to your heading (NOT YOUR COURSE OR TRACK)..

As far as your calculated headings (E6B derived) not working out well.. I'd have to see the raw data, and the heading you came up with. That should all work out pretty well in a sim.. because the winds aloft DO end up being what you planned for.


VFR piloting is only limited by weather... visibility and cloud layers, mostly. VFR pilots can go anywhere that VFR conditions exist. Now obviously.. an IFR pilot is more skilled in navigation... and my rule is that you shouldn't be taking long X-coutry flights until you ARE instrument rated..But there's no FAA rule about it.

If there is no heading change at a fix (or waypoint, or airport.. or any other VFR reference).. there's no need to make it two seperate legs.. But that's a personal thing. There's certainly no harm in making yourself practice all that stuff. IFR flights are different.. in that a fix (or waypoint, etc.) could very well end up be a reporting point.. and could very well end up being where ATC might change your flight-plan on you   ...  so it's a little more important to know your status (fuel remaining, etc.) at each leg.

Note:  (altitude, not height)

If you're gonna fly into the mountains.. pretty much climbing the whole time.. planning gets a little tricky. This isn't something a VFR pilot is likely to do. A flight like that would be filed IFR, more times than not. That aside. ..  You need to keep in mind a new variable. Your ground-speed will not only be affected by wind.. but by the fact that you're climbing. You've introduced a new angle. Planning for TAS and computing ground speed from that won't be accurate in a climb. The easiest thing to do is to just add 20% to your times.. hrence 20% more fuel.. AND remember that your burnning fuel at a power setting much higher than normal cruise (you're gonna find out why pilots don't like non-turbo-charged airplanes for mountain flying..lol).

As far as getting accurate data ? This can be a fun learning experience too. Take the plane out and make your own chart (KIAS vs Fuel-flow for different power settings) (always remembering to lean properly). Also note what type of vertical-speed you can hold; every 1000 feet or so while at Vy...  That should give you a good data-base.

ALL this stuff is making you get that piloting frame of mind firmly anchored in your noggin  


I'll check back in tonight.. when I get home..