Firewall design finished

After trial fitting the engine in different positions, I landed on the following position, down and side thrust for the engine:

As mentioned before, I didn’t quite like the commercially available mufflers and didn’t know where to fit them inside the fuselage. Then, I got some valuable help from a fellow club member. We took up the challenge together and decided to try our luck at building a custom muffler in the shape and position of the original scale exhaust! Of course, it’s still not a sure thing we will succeed, but if we’d do that would be fantastic! This would be much more practical to install, it would be outside of the fuselage which is better for cooling, and above all, it would look awesome!

I took the only two photos that exist showing the original exhaust and measured the dimensions and angles, as well as the position where it would protrude the fuselage side. Then I’ve calculated the required volume. As far as I can see right now, position, angle and length would all be exactly scale, only the diameter would be slightly over-sized. Scale diameter would be 28 mm, I’m aiming at 40 mm right now.

Time to continue working on the firewall. This is the second version with better dimensions for the engine mount. I also drew the firewall from the kit on it for reference and cut a hole for the exhaust:

Here you can see the one degree side thrust and one degree down thrust:

The engine nicely fits onto the new firewall, fixed with 5 mm Allen bolts into T-nuts attached from the back:

Then I’ve built a test stand for running in the engine later on:

But it also serves another purpose: building the muffler! I’ve cut holes in such a way that if I fix the custom muffler into it, I have exactly the right angles both backwards and sideways. Also, I’ve added a piece that resembles the fuse side so I can test and fine-tune how the exhaust should pass through the fuse side:

But for running in the engine it wouldn’t be practical, and I also want to be able to work on the engine easily, so I’ve made it detachable using magnets:

The idea is to first build the custom exhaust, and when that’s finished and firmly attached, I will cut away the sides so the muffler can move freely when I’m running in the engine.