“No bird ever flew nonstop from New York to Tokyo, or raced 15 miles high at triple the speed of sound.                                                                                                   
  Birds do something else.   They do not conquer the air; they romance it..”

Peter Garrison

Jur's RV7 Aircraft Factory
3497 hours and counting

PDF

02-09/05/26 - Making front baffles - 14h

Written on . Posted in 6.12 Bill Lane Plenum.

With the diffusers modified and installed under the plenum roof, it's now time to tackle the front baffles. These are different than the original ones from Vans in the vans baffle kit when you have the Bill Lane Plenum so they have to be made by hand from stock sheet. There are some paper templates given in the Bill Lane (Front baffle templates at Sam James website section documentation is actually for the plenum v2.1 which is the Bill Lane plenum).
I cut out the paper template to evaluate the fit before cutting some real aluminum sheet. I had to tweak it here and there, especialy on the curvature of the engine and the gap in the bottom.

 When I was finally happy,I layed it out on the aluminum stock sheet and traced the contour and marked the location of the bending line.

After making a rough cut I fine tuned it on the 3M deburr wheel
I used my small bending brake and bent the side wall. 

Then fit it on the engine. It still needed a lot more tuning. probably because I was conservative on the bending line so that I would not bend it too short and end up with a gap at the engine.
I have a little too much now and continued deburring the inner curves down. Key here is to find the sweet spot of sanding down the bottom line that touches the CB-1002A ramp on the cylinder 2 baffle ramp assembly and the curvature on the engine. Deburring on one or the other will affect the gap on both sides.
Another thing to keep in mind is the angle at which the front baffle sits on the engine. It butts against a notch near the top of the engine.

Not a big deal to get this right, just a lot of work and some patience.

When I got finally satisfied, I did the same work on the passenger side front baffle. Important here to pay attention that the bending is in the other direction towards the front.

Bending

 Here is how it looks on the plane.

In the image below, I have :

- rivetted the anti rotation bracket to the CB-710B.
- with the angle on, I could make the small angle which attaches the bottom of the front baffle to the CB-710B bracket and rivetted it to the front baffle.
- drilled the angle to the CB-710B.
- drilled the top line on the front baffles to the plenum cover.
- aligned the diffusers vertically with the aluminum inlet rings and drill the side lines of the front baffles. 

The inner allignment of the front baffles looks good, this will be sealed of on final installation using high temp red RTV to seal any small gaps.