Fly Baby Owner Survey Results

Updated 27 October 2001

This page summarizes the results of surveying Fly Baby owners regarding their experiences.  The intial version of this is based on 20 responses that Pete Bowers received in 1989, and I have added several responses.

Construction Time

Unfortunately, Pete didn't collect the data based on building hours.  Instead, what is logged is the start date and the date of completion.

For the examples received so far, the average time of construction is:

6.6 Years


Engines were installed on the following percentages:

65 HP:      50%
75 HP:      10.7%
85 HP:      17.9%
90 HP:       3.6%
100 HP:     10.7%
115 HP:     3.6%
125 HP:     3.6%

Most are Continentals; the 115 HP and one of the 65 HPs was a Lycoming.  The 125 HP engine is a race-tuned A-65 from a Cassut.

Here's a comment from the owner of one of the 100 HP (Cont. O-200) Fly Babies:  "Hard to hold takeoff direction down runway on full-power takeoff.  Higher powered engine and narrow landing gear probably contribute to this.  Also rudder very sensitive.  We use partial power for take off until airborne."


Propeller sizes are described by the combination of the prop diameter and the pitch:  70 x 45, where it's 70 inches in diameter with a 45-inch pitch.  Prop designations usually incorporate this; McCauley props have part numbers like ACM6948 (diameter 69, pitch 48) and Sensenich units will be called things like 74AK-2-46 (74 inch diameter, 46 inch pitch).

Generally speaking, if you have a larger engine, you need a larger-diameter and greater-pitch prop to take advantage of the extra power.  If you're underpropped, the engine reaches redline speed at lower throttle settings, and if you're overpropped, the engine can't turn enough speed to produce maximum power.  From looking at the survey results, it looks to me like some of these airplanes have the wrong props for their propeller'll see some larger engines turning smaller props than some of the A-65 examples.  What we're probably seeing here is folks basing their prop selection on what they can find on the used market, rather than having a new one made.

Here are the prop size results from the survey.  My suggestion would be to pick a prop in the middle of the ranges shown.  I identify the "standard" application for some of the prop sizes, these are from the Aircraft Spruce catalog.

65 HP

75 HP

85 HP

90 HP

100 HP

115 HP

In the survey, about 75 of the props have been metal.  Metal props are a lot easier to maintain, but a lot more expensive.

Empty Weight

Best way to show the range of empty weights is with a graph:

It's interesting to note the ~150-pound difference in the reported weights with the same engines...

Problems and Experiences

Some of the builders provided in-depth information on some subjects.  Comments in various categories are summarized

Problems in Construction

These comments are combined from the "Comments on Plans And Construction" and "Problems during Construction" categories.  Of the 28 entries I have, half of them say things like "Excellent" and "No problems."  Several left the categories blank.  The comments below are all the negative ones in these categories.

Comments on Flight Characteristics


Changes Made

Note that these are NOT approved changes. These are changes individual builders made.   Not all are necessary, or even good ideas.   These are provided for information purposes only.

Comments? Contact Ron Wanttaja.