KJ-66.
the classic
The KJ-66 is the model turbojet most home builders start with. Its plans are freely shared, and a whole industry of kits and commercial RC turbines grew out of it.
The name comes from its 66 mm compressor wheel, taken from a KKK automotive turbocharger. The rest of the engine is built around it: a machined aluminium front, a sheet-steel annular combustor, a cast Inconel turbine and a tool-steel shaft on two small ball bearings.
It showed that a small, simple turbojet could be built in a home workshop and run reliably, with far more thrust than the earlier FD-3/64 design and at a lower exhaust temperature.
Published figures
- Thrust
- 75 N
- Max speed
- 117,000 rpm
- Exhaust temp.
- ≈ 570 °C
- Diameter
- 110 mm
- Length
- 240 mm
- Mass
- 0.93 kg
How it is built
- Compressor
- 66 mm KKK turbocharger wheel, vaned diffuser
- Combustor
- Stainless steel annular liner (316 / 310) with vaporiser sticks
- NGV
- Inconel, fabricated
- Turbine
- Cast Inconel 713 wheel
- Bearings
- 608-size ball bearings with fibreglass cages, fuel/oil mist lubricated
what it teaches us
- Balance is everything at 117,000 rpm.
- Tip clearance at the turbine is worth more thrust than any other tweak.
- A good starter and a clean start sequence make the engine easy to live with.
Sources
KJ-66 is a third-party community design and not a Vector Dynamics product. We claim no ownership, endorsement or affiliation. Building and running gas turbines is dangerous; follow the original documentation, local laws and proper safety practice.
Next: GR-180 →ready for a real kilonewton?
Beyond the garage
UAV and target-drone makers, manufacturing partners and investors: talk to us about the VD-100.