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I am about to fly from Gibraltar to Northern Japan with upgraded airports all the way (mostly payware) at about the distance from Gibraltar to Mallorca between them. The truth is I have hardly flown COTS thus far because when I bought it I only had Orbx PNW and Fjords but truly I love big airports with proper terminal buildings not generic ones and exotic locations plus a long part-way round the world route - it took me 6 months to finally get everything sorted (as an aside I still need at least Karachi and Kunming to make it complete but could not find any good ones).

Anyway I found a spreadsheet on simviation which allows me to enter all the airports so I have the distances between them so will do that.

With flight planning I have no idea how to calculate what altitude I should get up to or even how long I should remain there when I get there (max altitude for whatever flight). Given they are mostly not so long hops (fits into my life's schedule) I found during a test run that I was waaay too high.

I don't care about waypoints and navigation per se and will be using FSMAP the whole way but wonder about jet streams and such but know next to nothing truly how to use them or even if that is in FSX ?

Anyone therefore with flight planning tips ?

Please excuse my total ignorance on the topic.

I know that your takeoff weight will be a big factor in time to climb. If I'm heavy it takes 800 to 1000fpm airspeed indicated 150kts <>to 18k where I level off as the turbo's are heating up. Fuel is set to auto lean, manifold pressure reduced to 40 and rpm reduced to 2100. It takes time for airspeed to get up to 250kts. As airspeed reaches 250 I take the altitude hold off and let it slowly climb on its own. I prefer to cruise at 25000 on long trips at a average cost of .78 cents a gallon.
I don't know if this has anything to do with your question other than being a factor to consider. I've had numerous pressuration problems at 30000. This aircraft is not a modern jet and if you push the engines to hard, failure may occur... Just my personal experience.

Thanks sixgun but the angle I am looking at is different. As is usual with me I have missed explaining the context properly, sorry.

The main issue is that if I climb up too far then coming down may take too long and be inefficient considering the distance.

Consider this extreme situation just to explain the issue.

Lets say I climbed by the book with no regard of the distance to the destination airport and just reached recommended cruise altitude but then found myself with needing to circle the destination airport many times because you shouldn't be coming down greater than so many feet a sec cause then passengers will complain.

In this case I should not have climbed so high because the leg I was flying was too short for the 377 to reach max cruise altitude.

So I was wondering if there was a flight planner or spreadsheet which could easily automate this process.

If I input the distance it might calculate I can be at max cruise altitude for 1 hour or better to only get to x number of feet.

This would aid me especially with shorter legs and also to aid me in deciding when to start my descent.

Correct me if I'm wrong, but it doesn't seem like you want to get too heavy into the performance aspects of flying the 377. With that in mind, finding the answers to some of your questions requires only pencil and paper. To find your top of descent: you are at 21000 ft and wish to descend to 1000ft. 21000-1000=20000. You wish to descend at 500ft/min. 20000/500=40. Takes 40 min to descend. You want to descend at 200 kts. So [200x40]/60=133.3. So, thats your desired spd multipled by the time in minutes its going to take divided by 60 (minutes) You need to begin your descent around 133 nm from your destination. Its not an absolute figure, but a good place to start. As far as altitude you could get into the tables if you wish. Or you could just figure something in the teens for short distanes and something in the mid 20's for longer distances. As far as fuel goes, use the flight planner in fsx, look at the navigation log to get a rough estimate of fuel needed ( in pounds) . Again its a rough estimate but a good place to start and it will get you where you're going. Later, you can start to plan flights using more realistic figures.

In general, you have less to gain by going high in a piston aircraft. In jets, it's often worth it to go as high as possible, barely having any cruise segment, before starting down again. Cruise level selection is crucial for the overall economy. Not so in pistons, due to the specifics of how the fuel is converted into prop shaft torque/jet thrust, respectively. Going higher essentially gets you there a bit faster, with the same fuel used.

Every aircraft, engine and prop combination will have altitudes which render them more or less efficient, but the changes won't be staggering. If you don't have access to the specific information for your aircraft, aim to go as high as you need to get above the weather if your aircraft is capable of it. Just find an altitude which gives you an enjoyable flight.

Ok that was awesome advice guys - thanks a lot!

I found this spreadsheet "Excell FSX Flightplan Creator"
http://simviation.com/1/browse-Utilities-65-1

I just enter the airport codes and it calculates distance. I have then from columns I to P done some rough calcs using the info in Row I from the Pilot's Manual for the COTS 377.

Now I can see how long it takes given you cannot exceed 300ft per minute in the descent or babies will start crying!

Does this seem right ? - 600 NMs to go from 30,000 to 1,000 feet at only 200 feet per minute?

First column from COTS Pilot's manual

Climbing to 30,000 feet.......................Descending (200 ft/m) Distance (assumes speed 250 kts)
(142,000 pounds)..............................From altitude (feet).......Minutes....... (Kilometres).........(Statute Miles).....(Nautical Miles)

Torque PSI 197.......................................10,000...................45................347.......................216....................188
RPM 2350..............................................20,000...................95................733.......................456...................396
Elapsed time 67 minutes.............................30,000...................145...............1119......................695....................604
Distance (Nautical Miles) 230
Distance (Statute Miles) 265
Distance (Kilometres) 426


On page 60 of the PDF Accusim manual

As the engineer of the plane, do your best to avoid changes in “cabin
altitude” in excess of 300 ft /min and the folks in the back will be
comfortable.




Edit - just found this on page 117 of the PDF for pilot's manual for cots

Distance to Sea Level (not displayed) is only displayed when your aircraft is in a
descent. This can help you establish a steady descent. For example, if you are 100
miles out from your destination, you would descend at a rate that would put you on
the ground at 100 miles. This is a sea level calculation, so take into account your
airfield height when using this calculation.

Yes, it would take around 604 nm to descend 29000 ft at 200ft/min @ 250 kts. I think the key phrase is "avoid changes in cabin altitude" which is portant if you are handling the pressurization of the aircraft. You can descend the aircraft at 500 ft/min, or more, at higher altitudes, without adverse reactions from the passengers. 500 to 1000 ft is okay. Once you get closer to field elevation you should bring it closer to 300 ft/min and under.

Absolutely,30000 ft is do-able. But i'm not sure its important to climb so high. If you do, go slowly, with step climbs or you could overheat your turbo bearings! As "ft" mentioned earlier, there isn't the same necessity to climb higher to gain greater efficiency.

Ah I see !

Lets say I climb then to 20,000 feet.

Would you say 500-1000 ft a minute is ok down to 12,000 feet for example and then 200 ft a minute below that ?

I plan for a 500 ft/min descent all the way down to around 2500-3000ft above field elevation, then start to bring the descent rate towards 300 ft/min or less. You can descend faster if you need. But figure 500 ft/min as a good mark. If the flight engineer is handling the turbos and pressurization, then around 1000 ft above the field the waste-gate to the turbos is opened (turbo control switches set to takeoff) and the cabin is at ambient pressure. This is where, if you descend too quickly, you're going to hear the babies! Also, watch for the power drop as this happens and bring the throttles up to counter the drop.

20000 ft is fine. I usually fly between 20000 and 24000. But feel free to experiment with all of these parameters, including your rates of descent!

Awesome Jacques - problem solved.

Thanks dude!

Have fun! Best passenger aircraft for FSX ever created, I think!

I have done some research and put in all the numbers that Plan-G requires and have it on a network PC (got some numbers from Oskar's comments on this forum and others elsewhere).

It calculates when I should descend automatically in the flight plan because of the help I received here for the descent rate! Thanks! Even has a glide-scope kind of gauge to tell me if I am on track.

I chose the starting airport, sights along the way and the destination. I then looked at the pop-up altitude graph screen and chose 1,000 feet above the highest mountain on the route as the max altitude.

Cannot believe how great Plan-G is with the 377 and how little time it takes to learn how to use it (great step-by-step worked example in the manual). It has really changed everything about how I fly (I was using Fsmap before). Will donate for sure.

So first proper flight with COTS (overshot the runway though ). Will try ILS for the first time having just watched how simple the "basics" (I know there is a lot more to truly understand if you are fussy about flying real world style) on youtube - is that how that gauge works?! So simple!

Looking forward to more!


BTW From memory I found a website that stated that over the course of a "flight plan" the usage would be something like 540 US gallons per hour (put that figure in Plan-G). Obviously it is different depending on weight, how you fly - economic or performance cruise etc etc etc but I entered it for all stages of flight just to give a rough estimate.

Well the first question to ask is what's your distance for flights? That will tell you the altitude to climb to. On my recent 4470nm trip from mcdill afb in Florida nonstop to bassingbourn I climbed to 29k. I have recently found that climbing any higher then that really needs a good reason to go there. I've found that at 29k I can save the extra time to gain speed easier and get over the hump quicker since there's a little power left. So your saving about 30-45 minutes of climb and using that for cruise. I cruise at starting .63 manual mixture. So you gain add about 100-200nm to your cruise for free instead of climbing. So the reason better to good to go higher. Turbos are fine up to around 24k. If your turbos are hot any lower your climb setup isn't good. Remeber climb rpm and mp of 50-51". Rpm should be around 24-2500. Leave it at the top of the green. You should climb on auto rich only. The benefit is so slight that it doesn't make sense not to. The gain is only 3-6lbs/hr ea engine. At 24k take control of the turbos and keep them below 150. Yellow is fine as long as you aren't cruising in the yellow for turbos. Once the turbo lowers in temp raise the turbos 5% till all in.

So back to subject, cruise should be set to how far your going. 200-500 at 15-18k. 500-1000 18-24k. Anything over 1000 anything below 24k is too low. Manual mixture is a requirement. If you only use auto lean your throwing fuel away. More about this search for a max range contest it's explained in crazy depth. And works wonders. Any more questions feel free to ask. I have all kinds of info that not in the manual.

Be aware that the speed that you need to use for your time of descent calculation is not the indicated airspeed but the ground speed. You first calculate your true airspeed by taking into account your altitude, then you calculate your ground speed by taking into account the wind speed and direction at your altitude, and your actual course. Notice that the wind direction is given in true heading in weather reports so you have to make a magnetic variation correction. Use an E6B for those calculations.

Two things. One, this all depends entirely on the weather. Two, it's entirely of benefit to climb as high as you possibly can, and it doesn't matter if it's a jet or a piston engine. It's just that jets have a lot more trust and can maintain higher speeds, so it's not as much of a struggle as a prop plane is to climb.

All planes are effected by the same physics, when you give, you get, and it all happens in mostly equal quantities.

At low alt you have dense air which creates lots of power and the engines don't have to work hard, but that air functions as wind resistance. At high alt this reverses and although you have the benefit of thin air air also holds back your engines. Really it's a question of engine power. Since the B377 has so much of it, you can really fire up the engines if you want to.

At high alt you also have less gravity, which helps. It's not much, but it helps. I think at 40k it's a 0.4% reduction.

When it comes down to it, higher is better because of thinner air. It's more efficient. To prove my point, what's a B377's fuel economy in outer space? Infinity. I mean, I'm just proving a point, here. Higher is most certainly better, as long as, you know, you can get there.

But the question is, SHOULD you try? That depends. It takes a lot of engine power and fuel to climb and doing so is inefficient compared to just cruising, so the benefits of the high cruise need to outweigh the climb. The price you pay for climbing is very substantial. In my extreme example, the fuel it takes to put a spacecraft into orbit does not outweigh it's otherwise infinite fuel economy if your goal was just to get to the other side of the planet. You use 5% or 10% of your total fuel capacity in your B377's climb at max gross weight. That high alt had better be worth it. Is it?

Check out the winds aloft. You absolutely need to do this. Look at the different flight levels and see if the winds change much. You have to be weary of high altitude winds because they can be pretty epic. 100+ knots! But then again, they can be pretty epic in your favor.

So you can break down your cruise altitude into three conclusions.

Winds aloft are horrible: Climb just high enough to get out of the clouds/weather/turbulence/terrain and just cruise there.

Winds aloft are awesome: Float that joker as high as it'll go and ride the waves. Very low IAS okay since you'll have epic winds pushing you.

Winds aloft/flight plan are substantially variable in direction. You may have to do some step climbs or descents. Generally speaking step climbs okay and step descents you should be weary of, since you burned a lot of fuel to climb. As long as your flight profile has all of the ups before all of the downs, you should be good and feel free to get complicated to avoid those winds.

How high is the limit to climb a B377? The plane has way too much power and is limited by it's pressurization limits, but the established service ceiling of 32k or 33k is a pretty good upper limit. For a traditional, realistic flight you don't want to exceeded that.

I'm usually pretty lazy in my climbs, no more than 500 f/m, and descents are also lazy. If you're getting less than 300 f/m at climb power you should seriously consider if you should stop climbing. I use the 300-rule on all my flights in all sim aircraft as a decision point about the ceiling of my flight.

Hope that helps.