Airfield Models - How To

How to Make Pushrod Exit Fairings for Flying Model Aircraft

May 03, 2015



Home
About
What's New
History
Models Gallery
Model Building Safety
Articles
Mail & FAQ
Site Map
Site Feedback
Contact
Register
Add to Favorites
Tell a Friend
Comments
Design and Build Contest
Items For Sale
Search Airfield Models

Back to How-To Articles

 

Airfield Models (http://www.airfieldmodels.com/)How to Make Pushrod Exit Fairings for a Model Aircraft

It is funny that I almost never see exit fairings on model aircraft.  They are incredibly easy to fabricate and make all models more attractive.  In fact, I do not use them often enough, but I think they will now be regularly incorporated into models I build.

I made four fairings for Rustik.  Total time including glassing the fairings was about an hour.

Other than being more aesthetically pleasing, fairings also help keep oil and other crud out of the pushrod exits and make clean-up easier.

 
 
Measure the pushrod exit hole to determine how large the fairing needs to be. This model has pull-pull controls on both tail surfaces.  Therefore, the exits are relatively small.  Shown here are the two rudder cable exits.  The holes are drilled in the upper fuselage using the pushrod exit drill guide.

1/8" inner pushrod material is glued in the exits and sanded flush with the fuselage exterior.

Measure the length and width of the exits and select an appropriate piece of balsa to make the fairings from.  Make the fairing a little on the long side to begin with so you have some leeway in getting the shape right.

Select an appropriate piece of light balsa to make the fairing from.

A variety of tools can be used to hollow the fairing.  I use a round file, but sharpened brass tubing will work.  In a pinch, a standard twist drill bit can be used as a file on balsa.

Hollow the inside of the fairing to ensure the pushrod will not bind with it. Cut the groove at an angle inside the fairing.  The exact angle is not really important.  Just be sure that it is deep enough that the fairing will not interfere with the pushrod or cause it to bind.
The fairing is hollowed at an angle to more or less match the angle at which the pushrod exits the fuselage.

Here you can easily see the angle at which the groove was filed.  This probably took all of two minutes to do.

Trim off the excess material before shaping the outside of the fairing. The black dot indicates where the groove ends.  It is there simply to make it easier to see in the photo.  Otherwise there is no reason to mark this spot.

Giving yourself some room to work, saw off the excess wood.

The fairing is sanded to shape using various grades of sandpaper. In this case, smaller sanding blocks would have been more appropriate.

The wet or dry paper is 800 grit.  Believe it or not, even paper this fine will remove a lot of wood quickly.

Give the fairing a pleasing, aerodynamic appearance. The 800 grit was not fine enough to remove all the fuzz, but at this point it is good enough to finish, so I did not bother going to finer grit paper.  A nice streamlined shape is always attractive.
The walls of the fairing can be as thin as you feel comfortable making them.  They do not contribute any structural strength to the airframe and only need to support themselves. One problem I ran into the first time I made fairings was that I shaped the outside first.  It was difficult to cut the groove without damaging the fairing.  I learned that shaping the outside around the inside is a lot simpler.
Fairings significantly improve the appearance of the pushrod exits. Here you can see the two fairings placed over the exits.  They will be glued on after they and the fuselage are glassed.

I have never tried to cover small fairing such as these with an iron-on film.  I am not sure how it could be done as they are so small it would be an awkward endeavor.

Maybe a piece of covering wrapped to make a loop with the adhesive sides ironed together could be slid over the fairing.  A heat gun can be used to shrink it.  That might make it shrink to a perfect fit, but I can not say for sure because I have not tried it.

I am sure if you make them, you will find a way to finish them.  It might be best to paint them even if you use an iron-on finish on the rest of the fuselage.

 
 

Previous
Next

Make Perfect Fitting Model Aircraft Wing Saddles
How to Make Foam Tape Servo Mounts

Comments about this article

 
 

Back to How-To's
Airfield Models Home

 
 

Copyright 2004 Paul K. Johnson