The Corvair Powered Zenair 601XL
November 28, 2004
It's been a while since we've updated our 601 page. We've been very busy, and I trust that you've taken
an opportunity to read about Corvair College #8 and other events going on at
our hangar elsewhere on our Web site. In order to answer a number of questions that came in by private e-mail,
we're grouping together some operational notes on the 601 here which should prove to be of interest to
people who are planning on installing a Corvair in their own 601. In the above photo, you can see our 601
airborne with Gus at the controls over South Florida. This photo was taken on the way to the first Light
Sport Aircraft Expo in Sebring, Fla. This was the premier event in what will become an annual gathering to
specifically showcase Light Sport Aircraft airplanes. Our own Corvair powered 601 fits in this category
perfectly, and we had a commercial space of our own to display the aircraft and a firewall forward package at
The most frequently asked question about our aircraft is how well it fits into the new LSA category. The
answer is that it's a perfect match for the category. Grace and I traveled to Oshkosh for the very first
LSA Conference three years ago February. Working for EAA Publications, and having a monthly column in the
EAA's Light Sport Aircraft magazine, keep me closely in touch with the developments of this new category.
The 601XL model was specifically designed by the Heintz family to meet the then-proposed, now in effect Light
Sport Category airframe requirements. Our installation of the Corvair engine, now flight proven with more than
110 hours, including the round trip to Oshkosh this summer and more than 20 passengers since then, is an
excellent match and keeps the airplane within the limits of the category.
Potential 601 builders commonly ask how much our airplane weighs. When we weighed it just before its first
test flight, it weighed 755 pounds empty. We've altered it slightly since then, and today it tips the scales at
750 pounds empty. The gross weight limitation of the category is 1,320 pounds. Thus, our airplane has a 570
pound useful load. If you're new to flying, the useful load of the aircraft covers the passengers, baggage and fuel.
Our 601 has the standard 24 gallon tanks, which when full, subtract 144 pounds from the useful load leaving
426 pounds for passengers and baggage. We have extensively flown the aircraft near or at its gross weight for
many of its flight hours. Unlike many aircraft which perform poorly at gross, the 601 is an outstanding
design which can easily maintain 750 feet per minute rate of climb at gross, even on a warm, humid Florida day.
Most newer pilots, familiar only with common certified training airplanes, find this a very pleasing
difference from their normal training hours.
Further, I'd like to add that our airplane is certainly not the lightest combination possible of the 601 and
Corvair. Contrary to what many people think, the taildragger version of the 601 is heavier than the
tricycle gear model. Our own particular airframe started off life as a tricycle geared airplane, and only
later became the XL taildragger prototype. Thus, it has the internal structure of both models. We've also had
a chance to work on other tricycle gear XL kits and weigh the components carefully. It is my honest opinion that
a tricycle gear XL with a Corvair engine like ours could be built at slightly less than 740 pounds. This
compares very favorably with the other engine options for the XL. Most customer built 3300 and 912 powered
XLs finish up around 725 pounds. On the other extreme, Lycoming O-235 powered XLs generally weigh close to 800
pounds. The Corvair strikes a very nice balance between reasonable weight and being very affordable.
Above is a photo of myself speaking with a customer at our booth at the LSA Expo. We hit as many air shows
as possible every year. The direct feedback from speaking with builders and going to events in person is
invaluable when it comes to understanding the market, what people want and can afford, and what they're capabilities
as craftsmen are. In my experience, businesses that do not attend Oshkosh, Sun 'N Fun and many other events
each year invariably fail for the dual reasons of being out of touch and an understandable loss of customer
Above, my test pilot Gus Warren speaking with another customer at the LSA Expo. Gus has worked with me for
more than 10 years, and is well known as an excellent pilot with the distinguishing characteristic of being a
patient and articulate instructor on all issues relating to the flight of light planes. Gus' father, the
legendary Clare Warren, is a flight instructor with more than 20,000 hours of instruction. In our shop, Gus
extends his family's reputation every day. A large part of our success is due to addressing the complete needs
of builders, from basic instruction through installation, at free Corvair Colleges, in person at air show forums
like Oshkosh, and in familiarization and operational flights in our demonstrator plane. Offering less is a
dis-service to potential customers.
In the photo above, Gus is giving a pre-flight briefing to Derek Hulbig of Toronto, Canada. Derek drove
down for Corvair College #8 at our hangar. He's a 601 builder who is currently working to complete his Corvair
engine from our Conversion Manual. Like Gus, Derek is a very burly guy. Together,
they weigh more than 500 pounds. But the 601's efficient airframe, and its 44" wide cabin flew both of them
in comfort with a good rate of climb. In extreme cases like this, we do not operate the airplane with full fuel.
But two FAA sized people could fill up the 24 gallon tanks on the XL, still carry 86 pounds of baggage,
and be within gross weight. With the standard Corvair engine, this combination performs very well. With the
ground adjustable, 2-blade Warp Drive prop we specify, this combination will meet all of the LSA speed
requirements, including the top speed limit if the propeller is pitched to a low setting. In short, the
Corvair/XL combination meets both the letter and intent of the LSA Category, while being an excellent flyer
and an affordable, easy to build aircraft.
In the above photo are the brothers Gingras, 601 builders from Crestview and DeLand, Florida. They're both
pilots, but Glen, on the right, is a 25 year A&P who earns his living as a helicopter mechanic. Gus took
both of them for familiarization flights in our 601. When an aviation professional like Glen chooses a Corvair
engine for his own XL, it's something of a compliment. Being able to serve their needs, from information and
parts through flight experience, is the way we operate our engine business.
Of the 80 people who attended our recent Corvair College #8, 33 of them were 601 builders. Gus has provided
flight experience for about 20 Corvair engine builders in our own airplane. The 2005 air show season should
see a half dozen of our customers complete their own Corvair powered 601s. We'd be glad to have you as a friend
and customer and help you realize your dream of building and safely flying your own airplane.