Page 8 - Demo

Expectations
I have been flying the CJ3 for six years, both for business and pleasure as well as instructing in the airplane. Cessna (and Williams International) truly produced a great business jet in the CJ3. It has speed, range and economy that is hard to beat. And going into this, I had seen performance gains due to installing winglets on other business jets, but questioned whether it would really make a difference in the CJ3. My Tamarack test flight would ultimately change those assumptions. I enjoyed the first flight so much, I requested another one in California to confirm my observations (or at least that was my excuse).
From the Ground
My first flight in the Tamarack-equipped CJ3, which served as their test bed for this installation, took place at Phoenix’s Sky Harbor Airport. The first thing you notice when you approach the aircraft is its impressive ramp appeal. The winglets add approximately seven feet of wingspan and sweep up approximately four feet above the wing. At a distance, they might look similar to other winglets but once you come closer, there are obvious differences.
Rather than being a passive wing extension, the winglets are “active” flying surfaces similar in appearance to large trim tabs, on the aft portion of the extension. These movable surfaces make up the Tamarack Active Camber System (TACS) and are controlled by a system of electronic devices, which receive various inputs, including accelerometers. There is also the Atlas Control Unit (ACU) located behind the fairing on the right wing root. The ACU communicates with the TACS Control Units (TCU) located in each wing near the extension. It is these TCUs that actually move the movable surface, or TACS on the extension in response to aerodynamic loads.
When the aerodynamic load on the aircraft increases beyond 1.5Gs, the system will then move the TACS up to relieve
the load not only on the winglet, but the entire wing and thus the airplane. Using this ingenious technology, the stress on the airplane is even reduced in turbulence or normal flight maneuvers. It is this system that actually manages the load and is why the entire installation is termed Active Technology Load Alleviation System or ATLAS. In addition to providing performance gains, this design also allows the CJ3 to have an increased Maximum Zero Fuel Weight (MZFW) of an additional 400 pounds, which equates to two more passengers you can carry before adding fuel.
On to the Flight
With Nick Guida, founder of Tamarack in the right seat, and John McCann in the side “jump seat,” it was time to fly.
After engine start, we entered the fight plan into the Rockwell Collins Proline 21 Flight Management System (FMS). Our flight would consist of a simple, roundtrip back to Phoenix Sky Harbor (KPHX). The controllers were extremely helpful giving us the TFD4 OLIN transition from Runway 25L, then SSO VOR and return.
One of the first things you notice from the cockpit is the wingspan. I didn’t want to be the first test flight pilot to run into something on the ramp! But with the aid of the Cutter FBO line staff watching the wings, I carefully taxied to our departure runway. Upon takeoff, the CJ3 quickly accelerated to V1 (decision speed) and Vr (rotation) which were the same today at 102 (with full tanks).
I hand-flew the aircraft the entire one-and-half hour flight, with the exception of 10 minutes to test the winglets with the autopilot. I tried different climb profiles – Angle of Attack (AOA), IAS and pitch. In each profile, the aircraft climbed slightly better than a “straight” CJ3 with perhaps a 300-400 FPM increase in climb rate. I couldn’t calculate an exact number since I only spent a few minutes in each profile and the rest of the time testing the active nature of the winglets.
Tamarack Aerospace Group achieved FAA and EASA approvals for installation of its Atlas Active Winglets on the Cessna C525B CitationJet series in February.
6 • TWIN & TURBINE June 2018