4102 Nose Bowl

Product Description

4201 -Note, this part is no longer in production, it has been superseded by #4201-B

The 4201 was our ’standard’ nose bowl from 2004-2018. It was made in several evolutions, starting as one piece, and later becoming two. All evolutions came from the same plug I made in 2003, designed with round inlets 4.75” in diameter, and made to use a 13” spinner. Over the years, several hundred of these have flown. Although it is primarily intended for use on Zenith aircraft, It has also flown on two dozen other aircraft designs.
Since the beginning of its production, we provided stories and examples of how it should be finished, particularly focused on opening the inlets to at least 4.75” and installing simple ‘inlet rings’. While many builders haphazardly flew without theses easy and required steps, instrumented tests showed  the cowling worked much better when used correctly.
Over many years I modified and tested 4201 cowls with inlets as large as 5.5”, These were flown on the Highest power, slowest flying, Corvair powered planes with good success. In 2018 I began work on producing a “STOL Bowl” nose bowl to have a production part to suit such installations. Now completed and in production, it has become our #4201-B part. It included 5.5” inlets with molded rings.
Price = No longer available.
Postscript: Failing to open the inlets and install rings is akin to buying a new radiator for you car but leaving the cap off and only filling it with half the coolant. Sounds incredibly careless, but I had dozens of builders in 15 years fail to address these steps. The fasted their planes worked is a tribute to the Corvairs superior cooling. The new “B” cowling is an improvement, but it also takes care of the inlets for builders who might have failed to do so. -William


This fiberglass Nosebowl was specifically designed by us in 2003 as an elegant and aerodynamic performance cowling for the Corvair engine. Although we originally designed it for our Zenair 601, the Nosebowl will fit many other diverse Corvair applications. The 4.75″ round air inlets provide plenty of cooling air for Corvair powered aircraft with cruise speeds of 85 miles per hour and up. It is designed to be used in concert with the readily available Van’s Aircraft FP-13 spinner. The Nosebowl is made in a female mold. It is vacuum bagged and made of high quality fiberglass.  Its construction and compound curve shape yield a rigid yet light in weight part.

The use of this Nosebowl allows the simple clean engine installation. Many homebuilts are sold short performance and appearance wise by an ugly cowling. Utilize one of these Nosebowls and give your homebuilt the sharp looks and performance you’ve worked for.

I’ve been frequently asked if I’ll sell this Nosebowl to people utilizing engines other than the Corvair. Please note that a Continental and a VW are far wider than the Corvair and will not fit in this Nosebowl, and the Jabbiru engine is incompatible with our air inlets. Thus, we restrict sales to Corvair engine builders only. Besides, we designed this elegant cowling to be the hallmark of Corvair powered aircraft only. The latest version of this Nosebowl is two pieces, which simplifies shipping, installation and maintenance.


Related story:

Pat and Mary Hoyt’s 601XL on the Cover

Additional information

Weight 8 lbs
Dimensions 37 x 13 x 13 in