The high thrust is apparent on taxi, where ample use of beta or braking is required to keep things moving slowly enough. And the sound is definitely different from that of the PT6, higher-pitched and louder, but inside the cockpit with the Bose on, it wasn't bad.
One of the things that longtime Caravan pilots will have to get used to is the feel of the airplane on takeoff. Because the Honeywell engine turns in the opposite direction of the Pratt, the torque is also opposite, so left rudder, and a lot of it, is required to keep things moving in a roughly straight line.
And move they do. The acceleration is quick, and time to rotate comes in seconds. It's fun, and while Austin's 9,000-foot Runway 17L is about a dozen times longer than necessary, I quickly got the idea: This is a powerful machine that can be operated from some of the most demanding airfields (or approximations thereof) on earth.
Shortly after heading out from Austin, Bobby wanted to give me a chance to see the takeoff and landing manners of the Supervan, so we decided to stop by sleepy Lockhart, a little (nearly invisible) asphalt strip south of Austin Bergstrom. Somehow we found Lockhart - well, Bobby spotted it and pointed it out to me - and we aimed that way, overflying the airport and banking the airplane around for a tight upwind leg around to the downwind for the south runway, which at 4,001 feet in length seemed spacious. The area was quiet, and as we passed overhead my Caravan companion pointed out the feedlot on the airport. It seemed a perfect fit for a little Texas flying in a working airplane.
As we came around base to final, Bobby explained to me what not to do — chop the power too soon because the big propeller and tremendous aerodynamic drag of the installation make short work of whatever flying speed you have left. I understood, thought about it some more, reminded myself three times and then proceeded to do just what he'd told me not to do, but I managed to turn a really awful landing into a garden-variety botch job. When I looked over at Bobby, who had a big smile plastered on his face, he said, "I told you! Everybody does it!" I was glad he was entertained. Oh, and even with the healthy bounce and float, we still used slightly more than 1,000 feet. With a good performance, I could cut that distance in half, I figured.
This promised to be interesting. We taxied around for another go.
Performance Counts
In terms of performance advantages, the sexiest is, of course, speed. Texas Turbines says the Supervan 900 is between 25 and 40 knots faster at cruise than the standard Pratt-powered Caravan, and our flight bore that out. The Supervan is simply able to put out a lot more power at every altitude, giving it better forward speed at both the maximum power of the TPE331 and at the same fuel flow as that of the PT6. Reducing our power to match the probable true airspeed of the stock Caravan, we saw a notable reduction in fuel burn and, hence, a big increase in range. At just about every power setting, the Supervan can cruise faster on the same fuel, more economically at the same speed and higher at the same temps.
This makes short trips quicker and certain long trips doable in one leg. In the bush or in the mountains, these factors can mean added utility — in some cases a stop for fuel, if possible, wouldn't be necessary — and added safety thanks to better reserves and escape options, and improved economy.
As you might expect, takeoff performance is spectacular, on average more than 30 percent better — this for an airplane that's an excellent short-field performer to begin with. At its max weight, the Supervan, which enjoys a 260-pound gross weight increase over the stock Caravan to begin with, still gets off the ground around 400 feet earlier than the Grand Caravan does. And the Supervan clears a 50-foot obstacle around 1,000 feet sooner than the stock airplane, doing it in around 2,000 feet.
Rate of climb is impressive, with the Supervan enjoying a 1,400 fpm maximum rate of climb at gross weight on a warm day, compared with the published figure of 800 fpm for the stock Caravan. We felt the improvements in takeoff roll and rate of climb going out of Lockhart too. Light on fuel but with five people aboard, we were off in a few hundred feet — the airport didn't feel necessary. A small field would have sufficed. Once airborne, I pulled the nose up, chasing the best rate of climb of 90 knots indicated, which gave us a rate of climb approaching 2,000 fpm on that day. Near sea level on a cool day on a 4,000-foot runway, the extra power was meaningless to us. Under marginal conditions, however, say on a very hot day at high altitude with a big load, it could make all the difference between being able to make a flight (or make it with breathable margins) or not.
Though it is the primary difference between a stock Caravan and Texas Turbine's Supervan conversion, the added power of the engine is only one of the advantages you get with the TPE331-12JR.
