Hi, guys I have some question about the exit hole in a canister's tunnel.

I'm building the H9 Edge 540 with the ZDZ 80, have a KS 89 canister muffler to be placed inside the fuse.

I have made a tunnel for it with a diameter of 85 mm, the canister has a diameter of 65 mm, look at the picture!

My problem is that I have also to make a curve for the air to exit on the bottom of the fuselage. No problem about the construction, but I wish to have some advice about the area and shape.

Do you think is better to gain higher pressure or higher speed just before the exit out of the fuselage ??

Because I have to shape the duct with an exit area bigger or smaller to obtain that.

I have seen many picture of german plane with a tunnel and exit curve like the one below, I understand that this is made by a german company, but I whant to do it myself because I think is not so difficult and I already have the duct now!

What can you tell me about that ?

Also a constant diameter till the exit can be considered, and is actually what I'm planning to do!

Moreover I don't like to live the hole at the exit as it is, but instead I wish to close the hole and make 10 opening divided in 2 row at 45 deg, just like the second picture but with a different number and dimension of the aperture.

Now the number and area of the 10 opening equalize the area of the duct (so no change in speed or pressure at the very and of the exit), but to obtain a sufficent area for cutting this opening, I have had to enlarge the duct at the end (gradually till the duct encounter the fuselage) so In this portion I have a pressure increase, but the air can't go anywere because the bottom of the fuselage let only escape the air allowed by the aperture size (that as said before is equal to the area of the duct).

Does it make any sense ?

I hope to have been clear enough, sorry for my english !!




Best Regards

Gianluca