When it comes to payload and range, the Encore runs laps around the V in my experience. Thats an easy, all day, everyday trip in the Encore! EVV-BFI is a different story.

From the operating manual.

It all depends on how you fly it. FL350 and MCT you burn fuel like crazy, which seems to be the normal way most fly it. FL430/450 and LRC, not so much.

Book says at mid cruise weights, FL450, ISA, MCT is 869 pph, 379 KTAS. I suspect I will be faster than that since I have been beating book consistently.

The range profile chart for LRC, FL450, ISA says that 4800 lbs of fuel will go 1630 nm in an average headwind of 40 knots. That leaves 1000 lbs reserve, which is tight, but manageable. The range profile chart includes taxi, takeoff, climb cruise, descent fuel, and includes allowance for the step climb required to reach FL450.

My modeling of this is that going west is about 50% success rate, winter being the worst time. Going east is nearly 100% success rate. This results in a average success rate of 75%. Given the situation, this is the best I can do for single pilot jet. The only thing better would be an SII converted with Williams, but lack of choice and other compromises with that airframe ruled it out. It should be noted that the winds at FL450 can be quite a bit less than those below FL410, so it can be quite advantageous to climb that high even if true airspeed goes down.

The proof will be in the doing, so I'll see how it works out in real life. Whatever the outcome, it will be a great improvement over the MU2 which can require TWO stops on the worst days to go west.

Mike C.

Can anyone explain the above? or how it relates to or supports?

Empty weight is 9243 lbs.

Max ramp is 16,100 lbs.

Max fuel is 5814 lbs.

I can thus load up 1043 lbs with full fuel. That could be 5 people, or 4 with heavy baggage.

That would go up to 1443 lbs if I had the 16,300 lbs MGTOW STC, but I don't want that because it lowers main gear cycle life.

I do have the 12,200 lbs ZFW upgrade. That means I can load 2,957 lbs in the cabin. That would be 328 lbs average per seat, which will never happen. That still leaves 3900 lbs of fuel, a decent amount.

Mine is quite a bit lighter than average. Garmin avionics upgrade reduced empty weight by 380 lbs. The pre mod and post mod weights are from actual weighing, not by math.

I've got another 100-150 lbs of possible weight reduction which could occur in the future. I intend to have the lightest V there is.

I am tail heavy. I need 200 lbs ballast flying solo, 50 lbs flying with 2 aboard, and no ballast with 3 or more. I did not have the avionics shop install permanent ballast which allows me to optimize the ballast. Operating near the rear CG limit makes the plane climb and cruise faster. Most unmodified examples struggle keeping the plane from being nose heavy, the prior owner pilot complained about that for my plane.

Mike C.

From the operating manual.

It all depends on how you fly it. FL350 and MCT you burn fuel like crazy, which seems to be the normal way most fly it. FL430/450 and LRC, not so much.

Book says at mid cruise weights, FL450, ISA, MCT is 869 pph, 379 KTAS. I suspect I will be faster than that since I have been beating book consistently.

The range profile chart for LRC, FL450, ISA says that 4800 lbs of fuel will go 1630 nm in an average headwind of 40 knots. That leaves 1000 lbs reserve, which is tight, but manageable. The range profile chart includes taxi, takeoff, climb cruise, descent fuel, and includes allowance for the step climb required to reach FL450.

My modeling of this is that going west is about 50% success rate, winter being the worst time. Going east is nearly 100% success rate. This results in a average success rate of 75%. Given the situation, this is the best I can do for single pilot jet. The only thing better would be an SII converted with Williams, but lack of choice and other compromises with that airframe ruled it out. It should be noted that the winds at FL450 can be quite a bit less than those below FL410, so it can be quite advantageous to climb that high even if true airspeed goes down.

The proof will be in the doing, so I'll see how it works out in real life. Whatever the outcome, it will be a great improvement over the MU2 which can require TWO stops on the worst days to go west.

Mike C.

At FL450, 85% of the atmosphere is below you. A sudden loss of cabin pressure to ambient would be 85% of the impact of walking out an open airlock on the space station without a space suit. This is my way of understanding the seriousness of the situation.

FL410 is not much better, 82% of the atmosphere is below you. You only get a few seconds more of consciousness.

FL450 makes a difference in two ways, a decrease in fuel burn and often a meaningful decrease in headwinds. I studied the winds aloft and it can make a 20 to 30 knot difference from FL410 to FL450. I also wonder whether it may open up more direct routings as well since it is usually empty up there.

Mike C.

At FL450, 85% of the atmosphere is below you. A sudden loss of cabin pressure to ambient would be 85% of the impact of walking out an open airlock on the space station without a space suit. This is my way of understanding the seriousness of the situation.

FL410 is not much better, 82% of the atmosphere is below you. You only get a few seconds more of consciousness.

FL450 makes a difference in two ways, a decrease in fuel burn and often a meaningful decrease in headwinds. I studied the winds aloft and it can make a 20 to 30 knot difference from FL410 to FL450. I also wonder whether it may open up more direct routings as well since it is usually empty up there.

Mike C.

Most people are not max range fliers. Every inch of altitude is *worth it* when needed for range.

It is possible I could be the only one who actually follows those rules.


The oxygen duration chart shows quite long use times:

With an 8000 ft cabin, which is what you get at FL450, over 17 hours.

I don't quite understand why the duration goes up when the cabin altitude increases. That seems backwards to me but that is what the chart says.

The cost to refill is about $100 at my home airport, which is way less than the cost of a fuel stop cycle.

The chart says I have about 1 hour for 9 people aboard (my max load). A 5 minute emergency descent would use 10% of my oxygen, so a 10% reserve would be adequate. That gives me 15 hours of usage.

In reality, if we have a full rapid decompression at FL450, doubtful any of the passengers actually get their masks on and oxygen started before they pass out. For the very few cases I know about of such an occurrence, that's been the result.

The most recent case I know of for a Citation is N804ST, a Williams converted 501, flying at FL430. This was 5 years ago.

A clamp let loose on the pressurization system, possibly from not being tightened properly, a plastic check valve flapper fractured, and the cabin fully depressurized in 20 seconds. The pilot was not wearing his mask. The cabin oxygen valve was selected to crew only, so no masks dropped for them. The pilot lost consciousness and the plane descended out of control. Pilot regained consciousness at 7000 ft and bent the wings in a pull out.

My plane is equipped with an improved metal flapper version of the check valve.

Mike C.

My friends williams converted citation lost pressure at alltitude also. At night over Guatemala.

I'd be interested in more details and the outcome.

Mike C.

They departed Guatemala and it occurred over the US. Problem was the flow pack which did not handle higher pressures/temps from the williams engines so well. I don’t think the pressure loss was complete. Sierra 501. He said the Clifford was better.

I wonder if it's because it takes less moles of oxygen to keep the inside of the human lung at sea level pressure when the ambient pressure is less than sea level?

Imagine your car tires are at 35 psi at sea level but you drive up to a mountain pass at 10,000 feet. For the sake of argument, tire volume and air temp remain the same. To keep the same 35 psi in your tires at 10,000 feet, you will have to let some moles of air out.

Edit: Did some more checking and as Mike's Citation uses a diluter-demand mask and not a positive-pressure mask, the pressure in the lungs pretty much stays at ambient cabin pressure. So the example above doesn't really work.

As far as I can tell, it works like this: At 37,000 feet the pressure in the lungs using the diluter-demand mask is going to be ambient, i.e. about 3 psi. At sea level, as O2 is 21% of the atmosphere, its partial pressure (and the body only really cares about the partial pressure of O2) is 3.1 psi. When the diluter-demand mask is set to 100% O2, although the atmospheric pressure is 3 psi at 37,000 feet, as long as 100% O2 is getting to the lungs, the partial pressure of O2 is also going to be 3 psi, which is that of sea level.

However, at 25,000 feet if the mask is still set to 100% oxygen, one breath of air is going to use more moles of oxygen from the system as the volume of the lungs is the same but the pressure inside the lungs (equal to ambient pressure) is now higher. Same volume, same temperature but higher pressure = more moles of O2. At 37,000 feet the partial pressure of O2 in the lungs from the mask was the same as sea level, but the partial pressure of O2 at 25,000 feet with 100% oxygen selected is the same as ambient pressure (5.45 psi), i.e. higher than at sea level, which is wasteful (unless needed for physiological reasons).

When the mask is set to diluter mode (the top four rows in Mike's oxygen chart), the mask mixes oxygen from the system with cabin air. You will note that oxygen use does not change radically from 8,000 feet to 20,000 feet using the diluter system.

He're a really interesting article on the respiratory system: https://courses.lumenlearning.com/cuny- ... -exchange/

Chip, you would have to remind me of popcorn right after I already ate dessert. At least they have a nice picture of an airplane on the back.

By the way, as part of your services do you check the aircraft records and make a list of all time-limited components with the times remaining?