Bad Ways To Save Weight

Sukhoi Example

Extra 330 Example

"Hop Up" Items

Package For a Typical 40%

72" wingspan (40 cc engine class) - 11 lbs.
80" wingspan (50 cc engine class) - 13 lbs.
96" wingspan (80cc engine class) - 18 lbs.
103" wingspan (100 cc engine class) - 21 lbs.
118" wingspan (150 cc engine class) - 27 lbs.
123" wingspan ( 160 cc engine class) - 31 lbs.
 

Planes in these classes could weigh in at these weights if they were designed and built with light weight in mind. Careful attention to every detail is necessary to achieve these weights. There are a few aircraft companies which offer aircraft which can be built to the weights listed above. Most of the other manufacturers' aircraft, whether they are kits, ARF's or ARC's, produce sport planes which can be lightened but will never be exceptionally light planes without major changes to the cowl, fuselage, wings and tailfeathers. You can reasonably  lighten planes so far before thinking about a new airplane altogether.

Planes of these weights must be carefully designed and tested. Strength is required in areas of high stress, and these areas are often defined through field testing of prototypes. We don't recommend that you take a hole saw to your current airplane unless you know what you are doing because you could weaken it and the results could be disastrous.

The weights of the planes described above are achieved by stripping off all unnecessary components such as pilot, instrument panel, and wheelpants and the use of standard mufflers rather than canister mufflers, wooden propellers, light cowl, CF parts, Li Ion batteries and more. An airplane which is the ultimate in light weight must be designed in at the very beginning, however, trying to do the best you can with the airplane you have can have very positive results.

1) Don't lighten the wings. It may well be possible to take weight out of the wings, but many planes, especially ARF's, have had a preponderance of wing failures.
2) Don't eliminate your redundant Rx battery pack and switch harness. Though tempting, we recommend the use of two batteries and two switches in Giant Scale aircraft.

We modified a Hangar 9 1/3 scale Sukhoi ARF for Tom Smith of the Sarasota Florida club. This plane typically  weighs 26.5 pounds with a Zenoah GT-80. We were able to save over 5 pounds to bring the weight down to 21 3/4 pounds. This weight includes a redundant battery and switch system (5 ounces) and pilot. The plane could be made 1/2 pound lighter (21 1/4 pounds) by simply removing these two items.
 

  
The plane could be even lighter if the wing was built with lighter balsa and less plywood, the fuselage had less plywood and more balsa, the cowl was produced from thinner fiberglass, and the ailerons were stiffer to be able to use only one servo per wing instead of two, the hatch was built with balsa instead of plywood and aluminum, and more. With the redesign and only one Rx battery and switch, no pilot and such the weight would be closer to 18 pounds. None the less, at 21 3/4 pounds the plane flies dramatically better.

**Lightening of the fuselage and using a lighter engine and eliminating ballast was accomplished by moving the wing rearward 2", and using a single servo pull-pull system to move the CG forward.

We modified a Hangar 9 1/3 scale Extra 330 ARF for Brian Jantzen of the Sarasota Florida club. This plane originally weighed 27.5 pounds. We were able to save 2 3/4 pounds to bring the weight down to 24 3/4 pounds.
 

Again, the plane could be even lighter if the wing was built with lighter balsa and less plywood, the fuselage had less plywood and more balsa, the cowl was produced from thinner fiberglass, and the ailerons were stiffer to be able to use only one servo per wing instead of two, the hatch was built with balsa instead of plywood and aluminum, and more. With the redesign and only one Rx battery and switch, no pilot and such the weight would be closer to 18 pounds. To avoid a tail heavy condition which would require moving the wing tube rearward for balancing, we did not lighten the motor box or use a lighter engine or mufflers.

Following are items which will take weight out of your aircraft. Combining these components with careful lightening of the airframe itself will result in an aircraft which is much more pleasant to fly.

Other Items you may need:
MPI Miracle Switches w/ 6V regulator
Li Ion Charger

Other Items you may need:
MPI Miracle Switches w/ 6V regulator
Li Ion Charger