Trimming the Rear HS Spar.

[msturgis]

Hey guys working through the HS. On the blue prints it says to "trim HS rear spar to allow for elevator contorl horns......." Then it says to "see drawing 27A"

For the life of me I can not find any drawing 27A, and have no idea how much to trim off.

Any help?

 

[Maury]

Look in you preview plans set. The plan you need come with the fuselege kit.
Rick Maury
RV 7
Emp/wings done Fus in the works

 

[msturgis]

Look in you preview plans set. The plan you need come with the fuselege kit.
Rick Maury
RV 7
Emp/wings done Fus in the works

I found the page thanks. But now unfortunately I still can't find any guidence on how much to trim.

 

[roee]

Matt,

DWG 27A is not provided in the emp kit, I think it comes with the fuse kit. But you should have all the drawings in your set of preview plans. If you never bought the preview plans, buy them. They're very useful in situations like this where you need to look/think ahead of the part you're actually working on, and you don't have all the sub-kits yet.

Now, DWG 27A doesn't provide any dimensions on this. It just shows a view that demonstrates why the cutout is needed.

DWG 3 shows that the width of the cutout is 2" (1" on either side of the centerline). It also does not show the depth dimension. The depth should be deep enough such that the elevator control horns will bottom out on the stop (which is part of the fuselage) before they hit the HS spar. Make sense? So ideally, the cutout should be just slightly deeper than what that works out to be. You could cut it even deeper, but then you're weakening the spar unnecessarily.

If you cut it now, you'll be guessing at the final dimensions. Too shallow, and you'll have to trim some more later. Too deep and, again, you'll be weakening it unnecessarily. For what it's worth, I measured mine and my final depth of the cutout was 5/16". Yours will most likely end up with a similar depth, but maybe not exactly the same (several variations in construction can contribute to small differences here).

My best advice would be to poll another few builders so that you get a good idea of the ball park, and then cut yours a little shallower. You can always trim off more later, when you actually have the thing test-fitted on the fuse with the elevators hung.

Good luck!

-Roee

 

[msturgis]

Matt,

DWG 27A is not provided in the emp kit, I think it comes with the fuse kit. But you should have all the drawings in your set of preview plans. If you never bought the preview plans, buy them. They're very useful in situations like this where you need to look/think ahead of the part you're actually working on, and you don't have all the sub-kits yet.

Now, DWG 27A doesn't provide any dimensions on this. It just shows a view that demonstrates why the cutout is needed.

DWG 3 shows that the width of the cutout is 2" (1" on either side of the centerline). It also does not show the depth dimension. The depth should be deep enough such that the elevator control horns will bottom out on the stop (which is part of the fuselage) before they hit the HS spar. Make sense? So ideally, the cutout should be just slightly deeper than what that works out to be. You could cut it even deeper, but then you're weakening the spar unnecessarily.

If you cut it now, you'll be guessing at the final dimensions. Too shallow, and you'll have to trim some more later. Too deep and, again, you'll be weakening it unnecessarily. For what it's worth, I measured mine and my final depth of the cutout was 5/16". Yours will most likely end up with a similar depth, but maybe not exactly the same (several variations in construction can contribute to small differences here).

My best advice would be to poll another few builders so that you get a good idea of the ball park, and then cut yours a little shallower. You can always trim off more later, when you actually have the thing test-fitted on the fuse with the elevators hung.

Good luck!

-Roee

Roee,

Thanks for the good info. I will take your advise and go shallow, then plan on doing a final fit later on.

-Matt