Building projects at the Toledo R/C Expo
by Jim Hiller [email protected]
Show overview
The 2013 Toledo Show is over, and it was again an exciting place for modelers. For those of us from the North, it was a great way to take a break from winter building and catch up with friends from throughout the region.
The turbine-modeling industry is not strongly represented at the Toledo R/C Expo; representatives prefer flying events to show the latest products. That said, jet modelers were all over the floor helping industry friends, displaying current projects, and taking in the sights.
Radio manufacturers
Radio manufacturers showed up in full force, including:
- Futaba
- JR
- Spektrum
- Hitec
- Airtronics
- XPS
They were all on hand showing the latest products—new toys for the boys (and girls).
Standout models and awards
- Terry Nitsch brought his latest Skymaster F-86, painted in the deep black of the Sabre Dance. The model features functional leading-edge slats and was named Best Finish at the Toledo Show. Terry’s model is ready for test flights, and we look forward to his impressions of slat effectiveness and flight characteristics.
- Greg Wright, from Aurora, Illinois, displayed a finely detailed F-100D building project. This sharp scale model earned the Best Jet award. It’s Greg’s second F-100; his first was built with aluminum Flite-Metal and skinned with titanium in the hot section. The new F-100D is finished in camouflage with realistic weathering and worn areas revealing the aluminum beneath.
- Curtis Wade showed the largest jet on the table: a Tomahawk Designs Hawk. Curtis’s winter project is a large model built for strong performance and was ready for test flights scheduled the following weekend.
The engineering feat: Bob Bush’s Skymaster A-4
The engineering highlight of the show was Bob Bush’s Skymaster A-4. Bob, known for flying a U.S. Air Force Thunderbirds F-100 Super Sabre for many years (wearing out three AMT turbines), surprised attendees with a scale Navy A-4 featuring exceptional weathering—reflecting the workhorse nature of Navy aircraft rather than the pristine finish of his F-100.
Bob engineered, designed, and built his own onboard hydraulic system and installed it with easy maintenance access. The system powers not only the landing gear retraction but also gear doors, tailhook, speed brakes, and flaps.
Key features of Bob’s hydraulic system:
- Hydraulic pump: a standard turbine fuel pump powered by a 1,800 mAh LiPo battery (serves as the hydraulic pump).
- Pressure control: a Robart pin-type onboard pressure indicator sets maximum operating pressure. As pressure rises, the pin extends and triggers a microswitch to shut off the pump to prevent overpressurization.
- Control valves: commercial hydraulic control valves actuated by individual JR 8411 servos (a bank of five), located behind the A-4’s removable nose cone.
- Reservoir: an RC car fuel tank used as the oil reservoir.
- Brakes: use an air cylinder moved by a JR 8411 servo to supply air pressure for braking—no air pump required for flight.
- Actuators and plumbing:
- 11 actuator cylinders
- Two hoses to each actuator = 22 hoses routing from the nose to the actuator cylinders
- Systems powered by hydraulics:
- Three landing gears
- Three gear doors
- Two speed brakes
- Two flaps
- One arrester hook
- Backup: an accumulator tank stores pressurized hydraulic oil large enough to allow one extension of the landing gear if the hydraulic pump fails.
Bob also addressed serviceability and disconnecting the wings for transport. A potential problem is disconnecting hoses without introducing air; Bob solved this with connector valves featuring a ball-check system to prevent oil leakage when disconnected. On the wing side he joins the two hoses to keep oil in the wing cylinders from leaking out, a slightly more complex procedure than disconnecting a normal pneumatic system.
Bob demonstrated the hydraulics often at the show. He ran the system until the battery was exhausted, then used the accumulator to lower the landing gear without the pump running—the backup worked perfectly. The scale gear movement with hydraulic actuation mirrors full-scale aircraft and takes approximately three seconds to retract.
I look forward to seeing Bob fly the A-4 as hard and as often as his F-100. He designed the system with frequent flying and minimal maintenance in mind.
Sources
- Jet Pilot’s Organization — www.jetpilots.org
- Toledo R/C Expo — www.toledoshow.com
Transcribed from original scans by AI. Minor OCR errors may remain.
