Spinning up for Spring: Turbine waivers

Written by Jim Hiller Turbine Waivers Column As seen in the January 2017 issue of Model Aviation.

Each year, more modelers become involved in turbine aircraft flying. Within AMA, we use the Safety Regulations for Model Aircraft Powered by Gas Turbines guidelines. Adhering to these guidelines is the responsibility of both soon-to-be, as well as experienced, jet pilots. Experienced jet pilots should share their knowledge to help new ones safely and successfully operate and fly their turbine jets. We never quit learning new things from our friends. If turbine jets are in your future, start by finding jet pilots in your area. Meet them and discuss your plans—they were once where you are. The least expensive learning you can do is through the advice of experienced pilots. With the cost of turbine motors and the complex models that we put them in, mistakes can get expensive. The turbine waiver process has been successful because we make it successful. It is modelers helping out fellow modelers. You must be prepared for your turbine waiver certification flight. What does this mean? Print a copy of the safety regulations, Document 510-A from the “AMA Documents” section of the AMA website, and read it. Also bring a copy of Document 510-D, the Fixed Wing Turbine Waiver form. This must be signed by both a contest director who holds a turbine waiver and another pilot who holds a turbine waiver. A number of turbine-related documents can be found in the “AMA Documents” section. When you show up at the field for your turbine waiver qualification flight, bring your airplane and a CO2 fire extinguisher. If you show up with a dry chemical extinguisher, others will know that you are not serious about jet modeling. Using this type of fire extinguisher on your turbine engine is an expensive mistake. It is corrosive, seals itself to hot metal, and destroys the hot metal it contacts. Don’t allow a dry chemical fire extinguisher on the flightline. Spend the money to buy the right equipment. Expect to be asked some basic questions about turbine safety regulations. They were developed and refined throughout the years as experience with turbine modeling grew. The safety regulations are a starting point that I hope sets new jet pilots in the right direction.

How about a pair of CARF-Models Eurosports with some imaginative paint schemes? These great-performing jets are fun to fly. Nick and Sebastian, from the Chicago area, have made plenty of flights on their Eurosports.

The qualification flight is an opportunity to practice proper techniques. Begin by preparing the start area. Position your airplane in a safe position, with the tailpipe pointing in an appropriate direction and the fire extinguisher readily at hand. Use your ground support unit to monitor the turbine during startup. You need to monitor the sequences to see how the temperature and rpms are responding. With experience, you will be able to detect startup issues before they get out of hand and cause a hot start. Now is the time to demonstrate your flying skills. The most important thing is to show safe and controlled flight. You do not need to demonstrate the aerobatic skills of a precision Pattern national champion. The takeoff should be straight down the runway centerline, not varying more than 10 feet from centerline. It’s a tougher goal than you think if you are not experienced with flying off of a paved runway. Strive for the same goal on landing—steering the model straight after touchdown to a controlled stop. Ending off of the runway and in the grass will not impress anyone. These two items are some of the most difficult to perform and are in the demonstration flight for a reason. Off-runway excursions can endanger fellow pilots and spectators if a jet comes toward the flightline or a crowd. This year, I observed numerous pilots having trouble transitioning from large-propeller models to turbine aircraft. All had difficulty with landings, or more accurately, the landing approach. Jet aircraft do not have the drag that a propeller does when the engine is idling, slowing the airplane to a set glide speed. With a turbine model, a pilot must set the glide speed and rate of descent with the throttle. High-drag models that are in a landing configuration are easier to land in a steep approach angle. Some sport jets are weak in this area and have flat glides on final approach, requiring good speed control with the elevator to arrive at the landing spot. Not all aircraft are that way. There are many sport jets with good drag in the landing configuration that have high-drag flap setups or additional speed boards to aid in the landing approach. Deciding which model is a good introductory-level jet for you should be discussed with experienced jet pilots. The decision should always be based on your experience and skills. The quality of your landings can be improved with consistent, repeatable landing approaches. Arriving at the transition from the approach to the landing flare with the same speed, altitude, and approach angle will make your landings more repeatable. Most bad landings can be traced to a poor approach. Practice your landing approaches and don’t be too proud to go around when you are unhappy with the setup. A windy day will affect your approach. It’s a mistake to attempt to fly a long approach on a windy day. Keep your approach consistent, including the length. The farther out you are when you turn into the final approach, the more time you have to get behind your airplane. I have observed many approaches on windy days end up short, and then get behind on airspeed control, which typically stalls the model into a hard landing. It’s great to see so many new faces in the turbine jet community. It continues to grow, so jump in and enjoy. There have been plenty of new turbine waivers issued. The many aircraft available today are well designed and tailored for specific flight characteristics meant to optimize your flying experience. Introductory turbine jet models vary from foam ARFs and balsa kits to balsa ARFs and full-composite ARFs. Many of them are suitable for varying flying skills and experience. -Jim Hiller [email protected]

Sources

Jet Pilots Organization (JPO) www.jetpilots.org AMA turbine aircraft documents www.modelaircraft.org/documents.aspx#Turbines