Why this Friday project? Most of us stare at screens all week — fiber optics, AI clusters, submarine cables. On Fridays, we unplug and build. The challenge: create a fully capable FPV airplane that weighs less than a can of soda, uses zero exotic materials, and fits in a flat envelope. The answer smells like fresh-cut balsa and a hint of parchment paper.
Mass Budget
- 🏗️ Airframe target: ≤ 95g
- ⚙️ Electronics + FPV: ≤ 130g
- 🔋 2S 450mAh LiHV: ~32g
- 🎯 Projected total: 248g
- Sub-250g = no reg headaches
Friday-Friendly Build
- 📦 Flat-pack from 2 sheets of 12"x12" basswood
- 🪚 Cope saw + razor blade + sandpaper
- 📜 Parchment paper skin (yes, baking aisle)
- ⏱️ ~90 min assembly once parts are cut
Electronics Payload
- 🛸 1104 brushless motor (12g)
- 📡 2.4GHz Rx + 5.8GHz VTX
- 🎮 Micro servo x2 (aileron/elevator)
- 📷 Nano FPV cam (3.5g)
Step 01 — Skeletonized Wing (no CNC required)
We start with a 3/16" basswood sheet. Mark your rib pattern, drill a ¼" pilot hole, and carefully remove interior webs with a coping saw. Each cutout drops weight while keeping an I-beam-like structure — a Warren truss in wood. Rough edges get a quick sanding; the parchment skin will hide any minor crimes.
🔧 Pro tip: Score the cut line first with a razor to prevent tear-out. The skeletonized wing panel goes from 12g down to ~6.8g. That’s the kind of weight loss we celebrate on Friday.
Laser-cut version would be cleaner, but hand-sawn gives you bragging rights.
Step 02 — The Parchment Revolution
Conventional heat-shrink film adds 20–30g to a 1m span. Parchment paper? ~5g/m². It's naturally slick, bonds beautifully with light mist of spray adhesive, and can be ironed flat at low temp (no shrinkage). The leading edge gets a strip of Scotch tape to resist peeling at speed.
- ✅ Drag coefficient similar to tissue — surprisingly slippery
- ✅ Zero cost if you raid the kitchen drawer
- ✅ Full wing set weight: only 3.2g
- ⚠️ Not rainproof — but perfect for calm Friday evenings
Bonding recipe: 3M Super 77 (light mist), lay parchment taut, press, then seal edges with low-tack tape. The result is crisp, white, and utterly ridiculous — in the best way.
Flat-Pack Obsession & $12 Airframe
All structural parts nest onto two 12"x12" sheets of 3/16" basswood ply. Add four 3/16" square balsa rods (longerons + spars) and parchment. That’s the entire BOM. The whole airframe costs less than a craft beer flight.
• 2x 12"x12" basswood ply (3/16") — skeleton parts
• 2x 36" balsa 3/16" square (spar caps + tail boom)
• 2x 12" balsa 1/8" round (pushrod guides)
• 24"x24" parchment paper (unbleached for style)
• Scotch tape + thin CA glue
💰 Total raw material: ~$12 USD. Electronics extra, but you can cannibalize whoops.
Slides into an A4 envelope. Assembles in about the same time it takes to watch an FPV edit. Hand-cut version requires patience; laser-cut would be even faster (but where's the fun in that?).
Motor on the nose (1104 6500kV), battery tray under wing leading edge. We'll shift the VTX and Rx to fine-tune static margin to 12-15%. A digital scale and a tiny lump of clay will lock in the sub-250g CG. The goal is a plane that feels like an extension of your thumbs — floaty, forgiving, and regulation-free.
⚙️ Friday trade-offs (the honest engineering)
Balsa vs. foam? Foam needs thick skins for stiffness. Balsa skeleton + parchment yields higher specific stiffness for less mass. Plus, CA glue repairs are instant — no messy foam-tac waiting.
Motor choice: 1104 6500kV on 2S with a 3x2.5 prop makes ~90g thrust. For a 245g AUW that’s 0.36:1 — not a rocket, but perfect for gentle climbs and scenic FPV cruising. Lower kV would be more efficient, but this keeps current low and battery tiny.
Servo reduction: One aileron servo via torque rods + pull-pull elevator. Only two micro servos (4.5g each). Every gram counts when you're flirting with 250g.
📊 Funday Friday progress snapshot
- ✅ Wing skeleton prototype finished — 22g per panel (pre-skin)
- ✅ Parchment skin weight penalty: only 4.1g for full wing
- ✅ Fuselage stick layout nested on second basswood sheet
- 🔲 CG mock-up with dummy electronics: next Friday’s task
- 🔲 Hand-toss glide test (no motor) after fuselage assembly
The sub-250g math: Airframe currently at 50g (including parchment & glue). Electronics & wiring ~58g, 2S 450mAh LiHV 32g, motor+prop 15g, FPV gear 16g → 171g plus servos (9g) and Rx (3g) = 183g. That leaves a massive 60g+ margin for wiring, connectors, and a bit of reinforcement. Target AUW: 239g — safely under the limit. No registration, no remote ID, just pure FPV joy.
This is a live Funday Friday build. Next log: CG balancing and the nerve-wracking first glide test. All design files (DXF for laser) will be open-sourced after the plane proves itself.
📡 Chatter & build-along: Bluesky @windandwireless — #FundayFriday #Sub250Balsa