If you were around our workshop on a daily basis, would see that we are constantly weighing things. We are passionate about reducing weight, staying legal, and increasing utility in the design of our Belite 254 Carbon Fiber ultralight aircraft.
I weighed the Belite 254 demonstrator aircraft on certified aircraft scales today. This particular aircraft is loaded with options. It came in at 255 pounds, without fuel tank. Because the limit is 254 pounds (actually, 253.99999 pounds) this would seem to be a failure. (I mistakenly first weighed it with the fuel tank and with fuel, and it was way over... ooops.... take out the fuel tank and reweigh...)
Our fuel tank weighs about 3 pounds dry, so today's final weight was 258 pounds. Consequently, we were 4 pounds overweight relative to FAR 103. I'll explain how we solved the problem in a few moments.
Here's what's on the airplane:
1) 4130 Steel airframe / elevator / rudder
2) Covering system with UV protectant
3) Bungee landing gear
4) Grove gear
5) Grove hydraulic brakes
6) Enlarged tail wheel
7) Rudder steering
8) 45HP engine, derated to accommodate part 103 cruise speed (with more work to be done)
9) 3 blade Powerfin prop
10) 5 gallon fuel tank
11) Electric Fuel gauge
12) Airspeed indicator
14) Tachometer / Hourmeter
15) EGT / CHT
17) Turn & Bank
18) Instrument panel, made of wood
19) Transceiver and permanent antenna
20) Transponder and antenna
21) LIPO Battery System with current system
22) Engine Starter Relay (but no electric start with this current engine)
23) Voltage regulator for radio
24) Alternator (this airplane generates electricity to run avionics and charge the battery)
25) Gizmo Dock
I'm sure I'm forgetting something. It's loaded with goodies. The panel would be comfortable and pleasing to any VFR pilot.
My goal was to have a FAR 103 airplane with high technology construction (Carbon Fiber), amazing power, full panel, etc. So now I've crammed all this stuff into the demonstrator, and I'm 4 pounds overweight.
Here's the solution:
1) We quickly reconverted the gear from bungees to solid. This saves about 28 ounces. I then removed the turtledeck, as it is not necessary for flight. Another 22 ounces saved. Finally, I removed a chunk of aluminum which was simply not necessary. (We'd been using it as a base for fuel tank in the baggage compartment; no longer necessary.) It also weighed 22 ounces. Total savings: 72 ounces, exactly 4.5 pounds.
Final weight, as adjusted: 253.5 pounds. FAR 103 legal! Loaded with features, engine, and performance! It can be done. (If configured with a smaller engine, performance remains VERY SIMILAR and weight drops further -- the 28HP engine weighs 18 pounds less!!)
I've heard reports of guys breaking their bungees and consequently hitting the props/destroying the engines. I'm OK without bungees for awhile. We'll figure out something to add them back to the demonstrator sometime soon.
The demonstrator still has a little work to do in Wichita, but it will soon be ready to move to Oshkosh. For example, Friday morning, we're doing an air to air photo shoot.