November 1998 , Edit note:   Model autogyro building has progressed considerably in the past few years thru the efforts of a number of GyroNuts... .  This file is of the "mechanically" hinged rotor hub, commonly used a couple years ago  (`1996 and earlier) and while the use of this type hub is certainly still worthy,  we have progressed into the simpler and perhaps more reliable "flexible" rotor hub design... The building techniques/procedures shown here are to demonstrate that building an autogyro is not as simple and routine as the average model airplane ... jb

This is a sequence of photos showing the various parts of the Matilda Rotor Hub.    Essentially, this hub is identical for all practical purposes to the original MINNIE hub.   This hub design is a simplified adaptation / modification of the original dc hub designed by Emilio Cabezas, Madrid, Spain.

EDITORIAL NOTE:   (1999) This design is several years old, and is kept here for information purposes only.  The current Minnie has a new, simpler head and hub assembly.

Materials consist of 1/16" hard,  and 1/8" light ply, along with a 1" piece of 3/8" OD brass tubing, 3 nylon hinges,  about 6" of fiberglass strapping tape,   and a few 2 / 56 nuts & bolts.

The main hub section is only about 3" in size,  and weighs about 1 ounce.   This particular hub works well for rotors up to perhaps 48-50".   A smaller size for rotors up to 34" is being used on the MINNIE,  and is slightly smaller and weighs less than 1 ounce.    You can see the MINNIE hub by skipping to the last 3 photos.....



Here are the parts of the 3 blade hub during final, pre-painting assembly.     If you look closely you can see the nylon pin hinges,   some fiberglass tape,  and a pin or two...   The brass bearing sleeve,   the top & bottom plates,   and the 2-56 bolts & nuts are there also....


This a close view of the top of the central hub section,   showing the hinge slots,  and you can note the black blade incidence shims installed on the blade tangs (blade holders).


This shows the bottom of the assembled hub.    For an idea of the size,   it is about 5 1/2" across from tip to tip,   and the center hub is about 2 1/2" across......


This is the top of the hub.   Note the blade shims,  the hinges,  and the top plate.   It is near critical to have the blade tangs radiate at 120 degrees apart.   Accuracy is very important.   Of all the entire autogyro parts,   the hub construction along with the blades,   are most important to insure a successfully flying autogyro.


Bottom view,   with the plate removed.   These hubs were designed to be dis-assembled for repair if necessary.  The bearing used are model car 3/8" OD, 1/8" ID, ball bearings.   The two bearings are separated within the brass sleeve by a 3/4" long nylon spacer. By maintaining a minimum separation,  rotor wobble is avoided........


Exploded bottom view,  showing the hinge pins (3/32 music wire).... I paint my hubs flat black.


Exploded view, after painting.......


Beginning construction of the new plastic disk hinged hub.   All the parts have been cut out,  and gluing is about to begin.   I like to use epoxy and clamp all parts very tight.....  This particular hub is for the small MINNIE machines,   with rotors of less than 34", and it weighs less than 1 ounce.


This is the plastic disk hinge.   The plastic disk shown here has been cut from a coffee can lid.   I believe this material will be strong enough for the Minnie rotor....  It would be best to use thin  (.030)   Polypropylene if available, especially for the larger hubs for rotors of over 34".


Note the simplicity.  This hub requires a lot less time to build than the previous hub show above,  and is currently undergoing evaluation.........


To  Autogyro.com rev..1-28-99..jb