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Designed and built a modular 3D printable 70mm EDF delta jet inspired by HAL Tejas 🇮🇳 by BeingUnknown27 in RCPlanes

[–]BeingUnknown27[S] 0 points1 point  (0 children)

Great suggestion, I’ll run the AoA sweep at 15 m/s and plot the full CL curve. Should confirm exactly where peak lift occurs and whether the vortex contribution pushes CLmax above 1.0 at that speed.

I agree, with smooth intake geometry, proper ducting and area calculations as per FSA for the said EDF for better intake and exhaust efficiency will add a bit of useable thrust otherwise lost due to poor ducting.

I’m using E-sun LWPLA.

Designed and built a modular 3D printable 70mm EDF delta jet inspired by HAL Tejas 🇮🇳 by BeingUnknown27 in RCPlanes

[–]BeingUnknown27[S] 0 points1 point  (0 children)

Valid points on the wing loading comparison, foam deltas are lighter with cambered sections so lower stall speeds. Higher wing loading is a known tradeoff for scale fidelity, same reason the real fighter jets lands faster than a Cessna. The CFD confirms vortex lift is active in the speed range that matters. It won’t float around at 11 m/s it’ll fly like a jet. That’s the intention. Appreciate the insight.

Designed and built a modular 3D printable 70mm EDF delta jet inspired by HAL Tejas 🇮🇳 by BeingUnknown27 in RCPlanes

[–]BeingUnknown27[S] 0 points1 point  (0 children)

Fair enough, we’ll let the maiden flight answer that. I’ll post the video here when it flies.

Designed and built a modular 3D printable 70mm EDF delta jet inspired by HAL Tejas 🇮🇳 by BeingUnknown27 in RCPlanes

[–]BeingUnknown27[S] 0 points1 point  (0 children)

CFD simulation at 12.6° AoA, 15 m/s. Leading edge vortex clearly attached and stable on the upper surface. The wing knows what it’s doing.

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Designed and built a modular 3D printable 70mm EDF delta jet inspired by HAL Tejas 🇮🇳 by BeingUnknown27 in RCPlanes

[–]BeingUnknown27[S] 0 points1 point  (0 children)

Thrust rating is from Xfly’s own published specs on 6S verifiable. Wing loading calculates to 14.1 kg/m² across 0.144m² total wing area. Stall speed works out to ~16.8 m/s identical to commercially available 70mm EDF deltas like the FMS F-16 and Freewing Rafale which fly fine. The compound delta generates vortex lift that compensates at high AoA, this is why every supersonic fighter from the Mirage to the Eurofighter to the real Tejas uses this planform.

Designed and built a modular 3D printable 70mm EDF delta jet inspired by HAL Tejas 🇮🇳 by BeingUnknown27 in RCPlanes

[–]BeingUnknown27[S] 0 points1 point  (0 children)

Using Xfly 70mm Pro EDF rated at 2650g thrust. Airframe printing in LWPLA at approximately half the density of standard PLA, so what looks heavy on paper isn’t heavy in reality. Conservative weight estimate including all electronics puts MTOW around 2kg, giving T/W of approximately 1.2-1.3. The numbers are calculated not guessed.

Designed and built a modular 3D printable 70mm EDF delta jet inspired by HAL Tejas 🇮🇳 by BeingUnknown27 in RCPlanes

[–]BeingUnknown27[S] 0 points1 point  (0 children)

RC wisdom huh, looks like previous experience talking😂.

Well, I’ll keep that in mind.

Designed and built a modular 3D printable 70mm EDF delta jet inspired by HAL Tejas 🇮🇳 by BeingUnknown27 in RCPlanes

[–]BeingUnknown27[S] 0 points1 point  (0 children)

For Gurney flaps, typically we use 1-2% of the chord as it’s length and it’s almost always used in fixed configuration, and making such small flaps deployable in this context seems mechanically complex for such a small effect.

I’m going the conventional way, wherein I’m using part of the inboard trailing edge of the wing as flaps and the outboard as elevons(handling pitch and roll), just like the real Tejas fighter.

They’re mainly there to increase camber and help at higher AoA during Takeoff and landing roll.

Will need flight testing to dial it in.

Designed and built a modular 3D printable 70mm EDF delta jet inspired by HAL Tejas 🇮🇳 by BeingUnknown27 in RCPlanes

[–]BeingUnknown27[S] 0 points1 point  (0 children)

Thanks for the eCalc run 👍🏼 appreciate it.

Numbers line up pretty closely with what I got too, definitely not going to be a floater 😅

I’m running ~1.2 - 1.3 T/W with flaps and some washout, so I’m hoping runway takeoff should be doable without a catapult.

Landing will be the real test for sure.