Table of Contents
History of lap times
Engines for F3D pylon racing models
Propellers for F3D pylon racing models
Fixed or retractable landing gear ?
Challenging the wind
Flaps in pylon racing models ?
Landscape or portrait?
How it all works together
A Comparison of Pylon Racing Airfoils

Aspects of
Pylon Racing

Fixed or Retractable ?

On the one hand, a retractable landing gear eliminates the drag of the legs and wheels, which can be rather high (in fact several times larger that the drag of the tailplane). But on the other hand, the installation of a retractable landing gear also adds weight to the model, which has to be compensated by a larger lifting force, which causes more induced drag. The following figure compares the required power for a model with a fixed landing gear with a second model, having a retractable landing gear. This is done assuming different values for the additional installation weight and four different flight conditions:
  1. level flight at 100 km/h,
  2. level flight at 200 km/h (cruising from pylon to pylon),
  3. a tight turn at 100 km/h pulling 10 g, corresponding to the maximum lift available and,
  4. a turn at 200 km/h, pulling 20g.

Required power of a model with a fixed undercarriage, compared with models having a retractable landing gear. A ratio below 1.0 means that a fixed landing gear is better.

The results show, that at high speed, the retractable landing gear always reduces the required power by 2% to 3%, even if the installation would add 200 grams to the mass of the model. Only at uninterestingly low speeds and high loads the lighter fixed undercarriage model has an advantage. Pilots often say, that a model with a retracted landing gear has smoother handling characteristics, but this might be the result of the sleek optical impression.

Propellers for F3D pylon racing models
Fixed or retractable landing gear ?
Challenging the wind

Last modification of this page: 21.05.18

[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.

1996-2018 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

Impressum       Datenschutz