As I talk to the pilots and owners who have upgraded their Citations with our Active Winglets, it has frequently struck me that there is a lot of operational knowledge out there that it would be beneficial to share with the CJ community in general. This blog is the first in a series that will attempt to pass along some of that knowledge and spread the best practices for operating a CJ with Active Winglets.
In this edition, I’d like to talk about altitude, and specifically your cruise altitude. Now, we all know that we don’t always get the altitude we request due to ATC or airspace constraints, but it has a significant impact on the benefits you will get from Active Winglets. Let me explain.
I frequently give demo rides to pilots who rarely fly above the mid-thirties and have even met some who are less than enthusiastic about flying at FL410 or FL450, but that is where the real efficiency gains occur.
As pilots, we don’t really talk about “range” as a guaranteed number. Obviously, a 100 KT headwind can put a wrinkle in that non-stop trip you had planned. Instead, we talk about endurance. We say an aircraft is “a 4-hour airplane” or a “5-hour airplane”. Given that endurance, we then figure out if, given the prevailing conditions, we can make a trip non-stop.
Here’s where ATLAS really helps. For every 1,000 feet of altitude you gain 3 to 4% specific range. Think about that number. The table below illustrates the improvement of specific range vs. altitude during cruise.
This next table shows the flight planning for a 1300 nm leg. Notice the higher altitude will result in the lower fuel required.
Note that some of these are landing empty, but that is in the book. Several leg lengths show requiring way more than the tank can hold! See the performance charts here if you want to dig further.
For reference we set a world record of 1853 nm with a 26 kt tailwind in our CJ with winglets. The book says we would have burned more than 3503 lbs without winglets! We landed with 482 lbs!
Active Winglets allow you to climb to cruise altitude quicker, thus burning less fuel. That saved fuel, quicker acceleration at altitude, and elimination of the need for step climbs directly translates into more endurance and thus greater range. The key concept here is to get to altitude quicker where you will be burning less fuel. The reduced induced drag from Active Winglets also means that the power can be pulled back and you are still going to hit the MCT cruise performance numbers. So that “4-hour airplane” can become a “5-hour airplane” and that expands your operational possibilities.
The proof is always in the data, of course. One of our customers, Steve Foote, recently flew his CJ2 from Newburgh, NY to St. Thomas non-stop in 4 hours and 15 minutes. Steve looked at flight planning tools and no CJ2 that he could find had been previously capable of making that flight and arriving with an NBAA IFR reserve. The key was that he made the 1,500 NM trip at FL 450, quickly getting to the optimal altitude and thus increasing the endurance of the aircraft.
On our Tamarack flight in N52ET from Paris, Texas to Paris, France with only one stop in St, John’s, Newfoundland, the key was also getting to FL450 as expeditiously as possible to increase our endurance.
Our website has a lot of these stories, and I’d encourage you to browse through them. Or better yet, we have a lot of owners now flying with our Active Winglets who would be happy to talk with you about their personal experiences and techniques. Just reach out to us and we’d be happy to help you make those contacts.
Blue skies and tailwinds!