SLUF (A-7) 50mm EDF design

[JustPlaneChris]

I finally decided to dive into foamboard design using CAD. I've built several FB planes over the years, but they were either from other plans or just "cut and fit". This time the design is being done in CAD before any foam gets cut. I'm probably 20 hours in, with lots of errors. But, it's starting to come together. Hopefully over the next few weeks I'll be able to unwrap the surfaces and create cutting templates. Still on the "to do list":

Internal bulkheads for the fan
Internal structure for battery tray
Servo positions and pushrod routing

It's been fun so far!

 

[Daniel Liutan]

I finally decided to dive into foamboard design using CAD. I've built several FB planes over the years, but they were either from other plans or just "cut and fit". This time the design is being done in CAD before any foam gets cut. I'm probably 20 hours in, with lots of errors. But, it's starting to come together. Hopefully over the next few weeks I'll be able to unwrap the surfaces and create cutting templates. Still on the "to do list":

Internal bulkheads for the fan
Internal structure for battery tray
Servo positions and pushrod routing

It's been fun so far!
View attachment 178636
View attachment 178637

Looks great!

 

[Grifflyer]

You're off to a great start!! Awesome airplane!!
How big is the inlet hole? It looks like it might be a tad bit too small.

 

[Daniel Liutan]

You're off to a great start!! Awesome airplane!!
How big is the inlet hole? It looks like it might be a tad bit too small.

I have two versions of F8 crusader, which is the predecessor of A7.

The hobbyking 50mm EDF F8 has a ridiculous large nose inlet. But still not big enough to suck ample air flow.

The freewing 64mm EDF F8 has scale inlet and two cheater holes. This design make it a blast.

I strongly recommend Chris use the NACA cheater holes.

 

[JustPlaneChris]

Thanks guys! I calculated the inlet area, and it's actually quite a bit more area than the 50mm fan. Same for the outlet area. I guess I won't know if it's adequate until I try it. If it doesn't work, I'll hack holes in it.

 

[Daniel Liutan]

Thanks guys! I calculated the inlet area, and it's actually quite a bit more area than the 50mm fan. Same for the outlet area. I guess I won't know if it's adequate until I try it. If it doesn't work, I'll hack holes in it.

Yes, you are correct.
The F8 crusader use Turbojet Engine, which sucks less air but burns more fuel.
The A7 corsair use Turbofan Engine, burns less fuel but sucks much more air.
So the A7 has a larger inlet (That's why i like it more than F8).

But for an EDF, always hope the inlet as big as possible A straight smooth air flow would be much efficient than the cheater holes turbulence.

 

[FishbonesAir]

Did this ever go anywhere?

 

[JustPlaneChris]

Sadly, no. But I did end up building one using slightly different methods. Link here:

https://www.rcgroups.com/forums/showthread.php?4028809-A-7-Boxy-SLUF

I'm now building a larger one based on Jetworks plans. Link here:

https://www.rcgroups.com/forums/showthread.php?4300313-Jetworks-A-7-SLUF-Corsair-II-at-150-size

 

[FishbonesAir]

Interesting. I started to read the thread, then realized how long it was, lol. I'm trying to complete a FT Tutor for a fly in this weekend, so I'll have to get back to it.