I flew this afternoon and tested the effect of my “speed mods”.  See below:

The only difference between the runs, other than the speed mods was that it was 11 deg. cooler with resultant increase in MAP and Fuel Flow.  Not sure how to interpret the temp difference.  Obviously the engine made more HP, on the other hand the air was thicker.  Even tradeoff?

Here are the speed mods I made:

a)      Gap Seals:

1)      Both sides of Rudder

2)      Upper and lower Elevator

3)      Upper and lower Flaps

b)      Antenna base fairings with RTV

c)       Various seams and interfaces with RTV and/or Tape

Overall, I am fairly pleased with the results – although it took longer than I thought and I spent way too much time on my back on a creeper.

One minor drawback – when flaps are deployed my airplane “sings” to me.  High pitched humming sound – not objectionable.  In fact it could be considered a safety feature!

I think I am going to try it again to see if I can get more.  Here are my candidate improvements:

d)      Flap hinge fairings – there has got to be a couple of knots with those

e)      Bottom of ailerons – I have been told that there is a knot there

f)       My speedbrakes are slightly recessed and some of the screws are “boogered” or stand proud.  If I get them flush and smooth the screws that might be worth something.

As always comments, suggestions, expressions of incredulity, and explanations as to why the only reason for the increased speed is the decreased air temp. are welcome!

D. Brunner

N241DB