RADIO CONTROL JETS
Jim Hiller, 6090 Downs Rd., Champion, OH 44481
Tango ARF review
I had an opportunity to fly the new Tango Almost Ready-to-Fly (ARF) jet from Mecca Models. The Tango is a smaller model with a 67-inch wingspan, designed to be powered by 11- to 18-pound-thrust turbines.
The general layout is the now-popular twin-boom arrangement with a turbine mounted near the wing's trailing edge. Unlike many similar designs, the turbine is mounted out of sight inside the aircraft with inlet ducts leading to the turbine. No tailpipe is required with this setup, thereby reducing complexity, weight, and cost.
This is the first turbine kit to come from Mecca Models. Don Kanak of Planes Plus, the distributor of the Tango, is offering kit packages that include:
- PST 600 turbines
- Robart landing-gear setup for the Tango
- wheel and brake systems
The package prices make this an affordable jet.
Don allowed me to fly his Tango many times at the Heart of Ohio Jet Rally, and it was a pleasure. His Tango was powered by a 12-pound-thrust PST 600 turbine and equipped with the Robart retractable landing gear. With this setup, the Tango's overall weight was less than 16 pounds. The model is equipped to hold more than 100 ounces of fuel.
The Tango comes standard with flaps. Don has developed a speed-brake option for those who want additional drag devices to help set up for landing; the model I flew was equipped with the speed brake.
One Tango I flew was factory-painted in red, white, and blue. Don's other Tango—the one he flew all weekend—had a red, white, and yellow color option. This second Tango was powered by a JetCat P-80 and had the fixed-landing-gear setup.
Flight characteristics
I enjoyed flying the Tango. The power with the PST 600 was sufficient; there was plenty of power for normal flying. During hard aerobatics I preferred to leave the throttle at full power to carry momentum for the next maneuver, but that was not a real issue. With the large fuel tanks, I set the timer for 10 minutes and flew all 10 minutes on every flight.
The wide-track landing gear on the Tango makes ground handling predictable, even in a crosswind. The layout aligns the turbine centerline close to the wing centerline, so trim does not change with power application. The symmetrical airfoil gives the Tango true Pattern-flying characteristics: it loops inside and outside equally well.
Rolling maneuvers were good. I noticed some roll coupling in knife-edge flight, but this was easily mixed out with minimal offsets. The model holds knife-edge reasonably well and allows long, drawn-out slow rolls or point rolls. Minimal down-elevator is required for inverted flight when properly balanced. Snap rolls break cleanly and recovery is repeatable.
Slow flight is important for landing and approach. The Tango has a thick, symmetrical airfoil that slows well, and with the flaps it provides adequate drag for a nice approach angle. I found the optional drag brake unnecessary for most landings, though I used it on a few and it did increase the approach angle. This model stalls cleanly and is optimized for Pattern-like flying; the stall is predictable and recovery is not an issue. The Tango is a good addition to the ARF models available.
Landing-gear setup and tips
Last summer I noticed a variety of landing-gear setups on jet models. With minor landing-gear changes, many of these models could be made friendlier on landing. Some of the changes include the length of the nose gear and the stiffness of the landing-gear springs.
Suppose a pilot can land a model but it touches down a little fast and a little high. The model may bounce down the runway; each bounce becomes progressively larger. What causes this?
First, how a wing creates lift: the wing's angle of attack is changed as we slow the model by pulling up-elevator during the landing flare. This increased angle of attack allows the wing to make enough lift to support the weight of the model as airspeed decreases. If there is too much elevator, the angle of attack increases and the model can climb until airspeed slows to where lift equals weight.
I prefer to set my models nearly level on the ground. I measure the height difference between the wing leading edge and trailing edge near the center section (close to the fuselage) and set the nose-gear length so the leading edge is roughly 1/4 inch higher than the trailing edge. This setup may make the wing slightly negative at the tip if washout is present. I use this setup because almost all my flying is off pavement.
There are two main reasons for a level setup:
- Improved crosswind capability — the wing makes little or no lift during the takeoff roll or landing rollout, so the full weight is on the tires, providing maximum traction to deal with crosswinds.
- A greater landing airspeed and reduced need to get deep into the flare — give it lots of elevator and you can make a bounce-free landing.
When landing too fast with a long nose gear, the model may touch down on the nose gear first (a "wheelbarrow" landing). The airplane pivots around the nose gear until the main gear touches. The wing is then at a greater angle of attack while airspeed hasn't been reduced, so the model can fly back up. If caught on the first skip, it's just a bounced landing. If not, the following sequence can occur:
- The second bounce launches the model at a harder angle.
- Each successive bounce launches the nose up at progressively greater angles.
- The landing gear can break or the wing may stall and roll over, wiping out the landing gear from side loads.
A hard bounce involves the nose-gear spring compressing and then releasing all that stored energy, launching the nose up at a steep angle and setting up the dreaded series of hops. Why are nose-gear springs so strong? I don't know.
Consider how the aircraft weight is carried on the landing gear. On a typical 21-pound empty-weight model, the main gears will each support roughly 10 pounds, leaving the nose gear to support approximately 1 pound. Shouldn't the nose-gear spring be roughly one-tenth the strength of the main-gear springs? It sounds simple — and it is. This is why I like installing a weak spring in the nose-gear strut: it reduces the model's tendency to launch after a blown landing.
A soft nose-gear spring also gives you braking feedback. You can watch the strut compress under braking to help judge brake application. The nose-gear strut will collapse with a soft spring, indicating how hard you are applying the brakes. Normally we don't know we're braking too hard until the tires lock up, flat-spotting them and causing loss of directional control. With a soft nose-gear spring, you can watch the angle of the model as the nose dips and the strut collapses during braking.
Model setup and personal preference depend on how and where you fly. I would favor a longer nose-gear strut if flying from grass, as it reduces the load on the landing gear as the airplane picks up speed, transferring load to the wing and shortening takeoff roll. Because I fly jets off pavement, the setups discussed here are biased toward pavement flying.
It's time to pack the car and head for the field. I gotta burn some Jet-A.
MA
Transcribed from original scans by AI. Minor OCR errors may remain.
