2 different ways to change the drag on a plane?

What are some ways I can reduce drag on a single-engine plane?

• What are some custom hacks that can increase air speed?

• Answer:

  Keep the airfoil as free of bugs as possible.  Laminar flow wings, like those on a Cirrus, are extremely susceptible to contamination.  In those cases, a solid covering could cost you 10 knots or more.  Even less laminar flow wings, like those on a Cessna or Piper, can be affected by bugs.  In those cases it'd be just a few knots but everything counts. A good coating from a surface friction reducer helps too.  One of my clients uses Race Glaze on his wings - he coats the plane entirely once every few months and uses it as a touch up to remove bugs after each flight.  I think we're seeing an extra 3 to 5 knots for it.  This and keeping it clean are probably the cheapest and least laborious ways to get a little more speed. Be very careful about filing down anything like a rivet.  If you remove too much, you can compromise the attachment and potentially cause severe damage in flight.  If you do want to try that tactic (rivets can cause a lot of parasite drag), then take the plane to a reputable shop where you know the workmanship.  Better to err on the draggy side, even then. Wheel fairings, sleek antennas, submerged antennas... all that stuff will help.  If you want to spend a few dollars by making some modifications that have been STC'ed by the FAA, check out LoPresti.  These guys are hands down the best I've seen for finding ways to squeeze a few knots here and a few knots there out of your plane.  I've seen them add more than 10 knots to some older planes for not much money by changing 3 or 4 things.  You can find them here: http://www.loprestiaviation.com/index2.htm  Finally, consider your CG location.  An airplane with an aft CG will have less induced drag (and thus go a little faster) from the tail-down force caused by your horizontal stabilizer and a lower angle of attack on the wings.  Instead of going into a dissertation about why this happens, I'll link to a place that has already done the work: http://ma3naido.blogspot.com/2007/09/effect-of-load-distribution.html It is EXTREMELY IMPORTANT that you make sure you stay within your CG limits if you do this.  With modern computers and graphs it should be a really easy thing to do, but a lot of us don't do that very often anymore.  There are tons of iPad apps, flight planning software, and even just excel spreadsheets that are already made that will make this easier for you.  Just be sure to plug your specific weight and moment into the calculator before using it.  An aft CG will affect different airplanes differently.  If you're flying a Cherokee 6 then we're talking about 1 or 2 knots.  If you're in a Seneca, 3 or 4 knots.  A Baron can get an extra 8 knots out of a CG shift... and so on.