For any of you that have experience with the airplane I have a question. I was reading an article about the Tamarack winglets and read something that just didn't make sense to me. They talked about using a CPCalc system to determine how long it would take to clime to FL410 (before the winglets were installed) and the system said it would take one hour and 54 minutes.

My question is, how can this be right? What am I missing?

step climb?

I don't think so. Why would a computer calculator add step climbs in?

I am thinking it would be very rare you would climb to flight level 410.
I rode right seat in a CJ a lot and we never were higher than mid 30's.
Never flew more than 2.5 hrs though.

Because the airplane can't climb directly to altitude at the takeoff weight.

Step climbs are relatively common in lighter jets.

The climb can continue when you reach a certain weight, or perhaps a certain AOA indicating enough reserve lift available.

I looked up the climb numbers for the CJ, 525, serial #0001 and subsequent, in the Operating Manual, revision 4, 525OM04.

For MGTOW, ISA, the CJ climbs directly to FL410 in 43 minutes. At ISA+10, it takes 110 minutes, a step at FL390 until the weight is 9221 lbs. No other conditions require a step climb per the book.

I don't see anything that is 1 hour 54 minutes. Perhaps someone is exaggerating the issue to make the mod look better?

It should be noted that climb times are SUPER sensitive to temperature. Just 10C more really hurts the CJ. So when you add just a tiny bit of wing to the airplane, like a winglet does, then you can find these cases where the standard airplane takes a long time to get to altitude and the winglet airplane gets there in much less time. But this is something of a contrived situation, using a test case on the hairy edge. If you compared the two airplanes going to, say, FL390, you find the difference isn't so great any more. The lesson is don't assume what appears to be huge improvement in one condition means all others are proportionally improved the same.

Mike C.

I don't use CPCalc but Nick from Tamarack advised that was the numbers he got from it.

I've never not been able to climb direct to 410 at MTOW. It usually takes 45-55mins depending on temp. I tend to fly high on all my legs using 400 and 410 on my weekly 450nm trip.

The Williams will struggle at ISA+10 and hotter. It's been ISA+18 in my neck of the woods but that drops off to ISA to ISA+5 thru mid to high 30's. I've never seen it above ISA+6 at 410. So you have your climb rate drop off thru the late 20's but improves in the high 30's.

My profile is climb out at 220, the M.5 at the change over then I hold VS at 1000, thru about 340 I wind down to 800 and thru 380 600 and 390 500. Worst I've had is 300 ft/ min thru the last 1000 ft when ISA+6 and an increasing tail wind.

Just finished my 61.58 check at FSI @ SAT yesterday so I'll be starting the trip back to Oz where I pick up my CJ with the Tamaracks installed. Interesting to see the performance increase in climb etc. I don't believe the 25-30% claims.

Thanks

Andrew

The only thing I could think of is that the time calculated was actually 54 minutes vs 1 hour 54 minutes. I spoke to a pilot friend of mine that flies CJ's and he confirmed time to climb to FL410 is typically ~45 minutes.

You are right, no way it is almost two hours to get up there... it's time to land by then!

Here's a CJ coming out of LA, 30 minutes to FL370 no way to know how heavy he is. http://flightaware.com/live/flight/N199 ... L/tracklog

Here's one coming out of Denver, less than 25 minutes to FL400
http://flightaware.com/live/flight/DCM6 ... A/tracklog

Gerry, as an FYI, I'll take the evo!!!

The 400 isn't from sea level. So 25 isn't real.

Here is a sea level take-off direct to 410 I'm 43mins at MTOW.

Andrew

Yes it's a great bird! I'm doing some research for a family member though. I absolutely love flying my plane.

I flew a box pattern the other day trying to find out which of my two pieces of equipment was more accurate on TAS. I have a GRT similar to a Trillogy and then my Garmin G3X. At 17,500 the Garmin displayed 280ktas, the GRT displayed 285ktas and the average of my ground speed from the box pattern came to 293.25ktas. I'm aware that there will be some wind error and such but was surprised to see my actual true airspeed was a considerable amount more than the GRT display considering at FL280 it says I'm at 312ktas. I'm planning to have my prop converted to the Villinger de-ice and should hopefully pick up 5-8 ktas.