Aerodynamics & Flight Mechanics Troubleshooting Guide

This page helps you to cure the most common problems that you may encounter when flying your precious model airplanes.

The model airplane depicted below has some problems.


Photo taken during an F3A-X contest in Tübingen, 1983.

  1. inappropriate flight attitude:
    most planes are designed for flight with the wings in a level position. The fuselage is poorly shaped and does not create enough lift to counteract the weight of the model.
    Remedy: use a better fuselage shape and increase the fuselage height.
  2. center of gravity too far aft:
    removing the engine during flight shifts the center of gravity too far aft. This results in reduced longitudinal stability.
    Remedy: move the wing back towards the tail plane until the center of gravity reaches the 25% chord line of the wing.
  3. front end of tuned pipe open:
    The conical end of the tuned pipe should be connected to the exhaust of the engine (that is where the oily, hot mess comes out).
    Remedy: add a fuel injection and ignition system to use the pipe as a ramjet engine when the piston engine drops off.
  4. asymmetric horizontal tail plane with pointed wing tip:
    cutting away part of the tail does not improve handling capabilities. Pointed wing tips may be a means to reduce induced drag, if such a thing exists at all.
    Remedy: To compensate for the asymmetric drag, offset the engine to the port side.
  5. reduced aileron area:
    chopping off half of the aileron reduces roll rates. The drag reduction due to a smaller wing surface is quite small.
    Remedy: increase aileron deflection and add a wing warping servo.
  6. flying close to neighbors:
    the trees and houses are dangerously close to the model airplane.
    Remedy: cut the trees and demolish the house.

Last modification of this page: 03.01.07

[Back to Home Page] Suggestions? Corrections? Remarks? e-mail: Martin Hepperle.

Due to the increasing amount of SPAM mail, I have to change this e-Mail address regularly. You will always find the latest version in the footer of all my pages.

It might take some time until you receive an answer and in some cases you may even receive no answer at all. I apologize for this, but my spare time is limited. If you have not lost patience, you might want to send me a copy of your e-mail after a month or so.
This is a privately owned, non-profit page of purely educational purpose. Any statements may be incorrect and unsuitable for practical usage. I cannot take any responsibility for actions you perform based on data, assumptions, calculations etc. taken from this web page.

© 1996-2006 Martin Hepperle
You may use the data given in this document for your personal use. If you use this document for a publication, you have to cite the source. A publication of a recompilation of the given material is not allowed, if the resulting product is sold for more than the production costs.

This document may accidentally refer to trade names and trademarks, which are owned by national or international companies, but which are unknown by me. Their rights are fully recognized and these companies are kindly asked to inform me if they do not wish their names to be used at all or to be used in a different way.

This document is part of a frame set and can be found by navigating from the entry point at the Web site http://www.MH-AeroTools.de/.

Impressum und weitere rechtliche Hinweise für Deutschland