3D Flat Foam Airplanes: Sizes, Gear and Setup
3D flat foam airplanes (“profile foamies”) are aerobatic models cut from flat sheets of EPP or Depron foam, usually 24–43 inches in span and 160–850 g in flying weight. Their huge control surfaces and very low wing loading let them hover on the propeller, flip and fly slowly indoors, and EPP versions survive crashes that would break a balsa model. Popular examples are the Twisted Hobbys / RC Factory Crack Yak-55 series. Here are the sizes, the gear they need and how to pick one.
By Kyle HilsonUpdated: October 20264 min read
What is a 3D flat foam airplane?
A flat foam (“profile”) plane has a flat-sheet wing and a single flat fuselage instead of a 3D body. That keeps it extremely light. Combined with control surfaces that cover up to half the wing and tail and deflect 45° or more, it can fly the slow, high-angle 3D manoeuvres: hover, harrier, torque roll, rolling circles, waterfalls.
- EPP (expanded polypropylene) bends instead of breaking. Best for learning 3D and for crash-prone indoor flying.
- Depron / XPS sheets are stiffer and lighter per strength but dent and snap. Common for scratch-built profile planes.
- Foamboard with a paper skin is cheap and easy to source but heavier and dislikes moisture.
Common sizes and specs
The Crack Yak-55 family shows how flat foamies scale up (manufacturer figures from Twisted Hobbys, checked October 2026):
| Model | Span (in) | Flying weight (g) | Motor | Where it flies |
|---|---|---|---|---|
| Crack Yak-55 Mini | 24 | – | micro outrunner | Gym, small hall |
| Crack Yak-55 Lite | 32 | 160–175 | CSP 2203 1800 kV | Gym, calm outdoor |
| Crack Yak-55 | 32 | 204 | Vertex VS28-05B 1550 kV | Indoors and calm outdoor |
| Crack Yak-55 39″ | 39 | 375–390 | CSP 2213 1100 kV | Outdoor, light wind |
| Crack Yak-55 XL | 42–43 | 765–850 | larger outrunner on 3S | Outdoor |
The rule of thumb for 3D: thrust should exceed flying weight (a thrust-to-weight ratio of 1.5:1 or more) so the plane can hang on the prop and climb out of a hover. The method for sizing motor and prop is in sizing an electric motor for an RC airplane.
What electronics does a flat foamy need?
| Part | Typical for a 32″ profile | Why |
|---|---|---|
| Motor | 22xx outrunner, 1500–1800 kV | Enough thrust on 2S for hovering |
| ESC | 10–16 A | Small and light; headroom for hover current |
| Servos | 4 × 5–9 g digital micro servos | Fast, precise centring for 3D |
| Battery | 2S 300–450 mAh LiPo | Weight decides indoor performance |
| Propeller | Slow-fly prop, around 8–9 in for 22xx motors | Big prop wash over the tail for control in a hover |
| Receiver | 4-channel micro receiver, ideally with a stabiliser | Gyro modes make hovering much easier to learn |
Kit, ARF or scratch build?
- Kit (EPP, printed): pre-cut parts, carbon rods, control horns; you glue, hinge and install electronics. Build time is a few evenings.
- Scratch build: free or paid plans printed on paper, cut from 6 mm Depron or EPP with a sharp blade. Stiffen the wing with carbon strip and the fuselage with carbon rods; profile planes flex otherwise.
- Glue: foam-safe CA or UHU Por for Depron, hot glue for foamboard, and for EPP a contact glue or foam-safe CA. Normal CA melts many foams; the glue table is in building with Depron.
- Hinges: tape hinges or fibre-reinforced tape; 3D needs throws beyond 45°, so hinge gaps must be clean.
Are flat foamies good for beginners?
Not as a first plane. They react sharply, fly in all directions and need practice in orientation. Learn basic flying on a trainer or a slow flyer first (see best slow-flying RC planes). As a second plane for learning aerobatics they are ideal: cheap, light, very hard to break and flyable in a sports hall in winter.
- Set dual rates: a low rate with about 15–20° throw for normal flight, high rate with full 3D throws.
- Add 30–60 % expo on high rates to soften the centre stick.
- Balance at the CG shown on the plans; tail-heavy profiles are twitchy.
- Practise hovering high enough to recover but low enough to see the plane’s attitude.
FAQ
What are 3D foam planes made of?
Mostly EPP foam (bends without breaking) or Depron/XPS sheets (lighter and stiffer but more fragile), stiffened with carbon rods or strips.
What motor size for a 210 g flat plate airplane?
A 22xx outrunner around 1500–1800 kV on 2S with a slow-fly prop of around 8 inches gives more thrust than weight, which is what a 3D profile needs. The 204 g Crack Yak-55 uses a 1550 kV 28 mm motor.
Can I fly a flat foam plane outdoors?
Yes, in calm air. Light indoor versions blow around in any wind; 39–43 inch models with heavier gear handle light wind better.
Which foam plane survives crashes?
EPP models. They flex on impact and are glued back together in minutes.
More on this topic: the complete RC Airplanes guide covers the basics behind this article.
About 20 years in RC. Mostly boats in the NAVIGA Mini Eco Expert class, with many self-made parts; also a King Motor Baja 5B, a home-built electric plane, home-built nitro planes he has flown, and an RC helicopter. More about SwellRC
