Unstable EDF Racer Project

[Liam Walton]

I've dabbled in a bit of quadcopter frame design before but I've always had my eye on fixed-wing design. I've always been fascinated by everything on the leading edge of technology and I have never been too interested in mainstream aircraft. Unfortunately, this means that my first fixed-wing design is going to be quite hard to complete as no-one has ever done something quite like it. 

Essentially, I'm working on a cross between the X-29 and the X-36 optimised for small-scale flight. It will have the wings of an X-29 (forward-swept with close-coupled canard) and the yaw stabilisation of the X-36 (no tail, use split ailerons for yaw). I will go a step further and add thrust vectoring for pitch and yaw so it can hover and perform crazy maneuvers like the Kulbit. A quadcopter-style flight controller will be used to stabilise it since it's unstable in all axes.

It should be very efficient and fast but still ultra-agile. Hopefully, I'll even be able to race it against quads on tight FPV race tracks but still put on trick shows while flying LOS

It sounds crazy but I think it can work. Armed with an array of free professional-grade CAD and CFD software, I think I can handle it. Here's the early concept images for the top view, wing cross-section and ducting cross-section:


Next step is the design of the EDF inlet and exhaust. I'll draw it up on Fusion360 then analyse it in a simulated wind tunnel on SimScale. All the software I'm using is completely free on the condition that I don't make significant profit off it

[gbar7217]

I've dabbled in a bit of quadcopter frame design before but I've always had my eye on fixed-wing design. I've always been fascinated by everything on the leading edge of technology and I have never been too interested in mainstream aircraft. Unfortunately, this means that my first fixed-wing design is going to be quite hard to complete as no-one has ever done something quite like it. 

Essentially, I'm working on a cross between the X-29 and the X-36 optimised for small-scale flight. It will have the wings of an X-29 (forward-swept with close-coupled canard) and the yaw stabilisation of the X-36 (no tail, use split ailerons for yaw). I will go a step further and add thrust vectoring for pitch and yaw so it can hover and perform crazy maneuvers like the Kulbit. A quadcopter-style flight controller will be used to stabilise it since it's unstable in all axes.

It should be very efficient and fast but still ultra-agile. Hopefully, I'll even be able to race it against quads on tight FPV race tracks but still put on trick shows while flying LOS

It sounds crazy but I think it can work. Armed with an array of free professional-grade CAD and CFD software, I think I can handle it. Here's the early concept images for the top view, wing cross-section and ducting cross-section:


Next step is the design of the EDF inlet and exhaust. I'll draw it up on Fusion360 then analyse it in a simulated wind tunnel on SimScale. All the software I'm using is completely free on the condition that I don't make significant profit off it

Good one Liam, I have flown jets with thrust vectoring and have found them very responsive. Using the push/pull system on the wing surface might be better than using 2 servos, as one servo could faulter causeing the other servo to labour and burn out. Overall the concept is good, what material are you considering using in construction??

[Liam Walton]

I’m thinking of using a 3D printed nylon lattice for the wing formers with a thin EPP skin. Might even add tape all over it to get it slick and tear-resistant. Undecided on fuselage construction but the ducting will all be 3D printed nylon

[Liam Walton]

I'm using two servos because it's a split aileron. It can deploy the upper and lower surfaces up and down together as an aileron, deploy only the upper surface upwards as a spoiler, or deploy the upper surface upwards and the lower surface downwards as an air-brake. It can deploy an air-brake on the left wing to yaw left and vice-versa. When this is controlled by a flight computer, there is no need for a vertical stabiliser.

[Liam Walton]

I've updated the design to use a ring intake around the fuselage. This should be a lot simpler and much more efficient, allowing for higher thrust during high alpha maneuvers and higher top speed. Unfortunately, this means that the nose will be less structurally sound and more prone to falling off on unplanned landings due to the weaker attachment to the rest of the fuselage. Hopefully the thrust gains from a cleaner inlet will make up for the extra reinforcement weight required to keep it in one piece.

[gbar7217]

I've updated the design to use a ring intake around the fuselage. This should be a lot simpler and much more efficient, allowing for higher thrust during high alpha maneuvers and higher top speed. Unfortunately, this means that the nose will be less structurally sound and more prone to falling off on unplanned landings due to the weaker attachment to the rest of the fuselage. Hopefully the thrust gains from a cleaner inlet will make up for the extra reinforcement weight required to keep it in one piece.

What is the power supply you intend to use?? A 4s 2200ah might get it in the air for a while but you might need a bigger battery, which will add to the weight and stability.!!

[Liam Walton]

I’ll be using a 1500 4S (quadcopter battery; can survive 120A bursts) initially. I’ll eventually upgrade to something larger but I’m hoping the high thrust/weight ratio will allow me to fly at low-mid throttle mostly. I’ll be flying it like a quadcopter or a 3D plane so there won’t be a lot of WOT passes. That being said, batteries are going to be the biggest limitation

[Liam Walton]

I've completed the initial design and analysis of the fuselage and intake. This test was only used to see if there's anything inherently wrong with this style of intake. It looks fine to me so far. I'll refine it once i've finished everything else. (open image in new tab or save it to view the whole thing as it might be cut off on your device)

[Celwin]

Wow Liam, that's rocket science you're playing with there!

[Liam Walton]

Wow Liam, that's rocket science you're playing with there!

Haha, not really. I’m not doing any calculations at all. I’m just creating what looks right and then putting it into a virtual wind tunnel. If something doesn’t look right, I’ll change it. As for wing size, I’m making the wings as large as possible without getting too heavy.