Monday, December 5, 2016

Intro to Induction

This week I spent pretty much the entire week working on the Induction system for the 9.  As I've mentioned before I seem to have a problem with my engine running too rich at takeoff.  I sent the fuel servo back to Airflow Performance and there is nothing wrong.  I did buy one of their new induction systems because the next most obvious cause would be turbulent air flow at the inlet to the fuel servo.  Since the new induction parts didn't fit with my cowling I have been modifying them to work.  As you can see in the pictures below I came up with what I hope is a good solution.

I did get a chance to fly it this weekend and I found both good and bad.  The good is that the airplane is actually a couple of knots faster!  The bad, but controllable, is that on takeoff with the induction wide open I actually indicate up to 18 gph now.  Not the direction I was hoping to go with that number.  I say its controllable because I can adjust mixture manually to keep the fuel flow down where I want it.  Not sure what to do next.  Originally I thought it might be an indication issue but given the amount of power that I can add by pulling the mixture out to about 13.5 gph I don't know that it would be just indication.  

So the first thing I did was to cut the majority of the alternate air inlet off.  Then I JB welded some screen to the new inlet.  I then fabricated a cover piece of the same screen material and sandwiched a piece of filter material between the two screens.  This will allow air to flow in but no chunks.

The top screen is screwed to both sides and the edges are bent to capture the filter material.  This picture has the inlet upside down such that the alternate inlet will pull from the bottom of the cowling.
Here it is after Harry and I installed the new inlet.

This is the other side of the inlet showing the alternate air flapper valve controller.
Test flight with Harry and Jeff.  In this flight we buzzed Martins house, Jeff's mom and boss, and Harry's neighbors.  Then we went to Bremerton for some lunch.

And this is the next shot in the sequence.  Pretty cool photo even though we were not in tight formation.
Martin took this picture as we were making our second pass over his house.  Notice the jet behind the clouds on the right?