As I do not have a KR but use this list for information on the Corvair engines performance or problems, I do not usually have anything of value to contribute. However, I have built (well, almost) a 601 HDS, and I am in the process of building a 601 XL. There are a few statements in Friday's KR net that I might be able to add further information/clarification. The comparison of the build quality of the RV to the Zenair Zodiac series, 601 HD,601 HDS, and 601 XL is difficult to make, as the Zodiac can be, but most often is not in a quick build form, that is, not pre-punched rivet holes. Determination of where to rivet is up to the builder, with some "rule of thumb" precautions regarding proximity to the edge, pitch in certain areas, number of rivets, rib location, etc. I found the most challenging portion of the build to be the use of the metric system since Zenair flip-flopped back and forth with references made in both inches and centimeters. The 'plus' side of the non-pre punched skins was that your fit was as good as you made it (like the KR?). You also trimmed all skins to the proper size, made many of your own bends, built your own re-inforcements, added strengthening braces as you saw fit (landing gear, main spar, firewall,etc.), depending on your firewall forward, weight of engine, anticipated type of use, etc.
As Serge pointed out, the use of the pop rivets makes build time MUCH less, about 1/4 or less than that of an RV where the rivets must be bucked, and helps keep Momma in the kitchen instead of helping you with the bucking bar. The HDS model that Don speaks to NEVER reached a speed of 150 MPH in level flight. In general, Zodiacs have always been overstated in regard to top speed, and the 3 or 4 years that I participated in the 601 builders net pegged it at about 130 MPH, and that was with wheel pants and significant attention to fairing. It does not perform well with a heavy engine, the best is a Rotax ULS, 100HP model. It has the same FWF as the current 601 XL, but there is a caution that using an older Continental 0-200 should only be considered after "significant upgrade of the electrical system is performed", e.g. the lighter starter and a lightweight alternator to replace the generator. To my knowledge, the only person to approach Chris Heintz top speed figures was a George Pinneo, using the Rotax 912 ULS. The Subaru proved too heavy and difficult to cool, and, having flown an HDS with a Lycoming 0-235, I can say that engine made it into a C-172 as far as handling/flight characteristics, a truck instead of a sports car. VW power (without a PSRU) was inadequate and also experienced cooling problems, and the Jabiru 2200 was underpowered as an 80 HP mill. It performs very well with a Jabiru 3300. Handling characteristics are good, and for a "bumpy, pop-not-flush-riveted, high lift high dihedral low wing spam can", it can be a lot nicer to fly than any C-150. For one thing, it is 44 inches across in the cockpit so that you can fly it FACING FORWARD, one of the biggest reasons I chose it. The stick has the option of being dual control, one on each side, as do the rudder pedals (brakes on pilot side only), and dual throttle controls are also a feature. There are wing lockers when the leading edge gas tanks are used, and, if one doesn't mind having a fuse gas tank, an additional 5 to 16 gallons can be 'placed between you and your engine', making it fly longer than my bladder will withstand. It has no flaps, and has difficulty making the landing speed for an LSA, but can easily ensure staying below top speed limits by using a fixed prop. According to one owner who recently sold his with a Jabiru 3300/fixed prop, he was able to achieve the slow landing speed by adding Vortex Generators to the top leading edge of his wing surfaces, and the lower side of his stabilizer. Personally, I found factory support to be very good. Questions were answered in a timely manner, both by phone when needed or email as appropriate. I think a lot depends on your experience level and the type of support you require, but the Heintz family is noted for their helpfulness. I did attend the 'week-end build your tail factory session' in Mexico, MO, and it was extremely helpful as I had zero experience in working with metal/riveting. A very big plus for this 'training' is that two can attend for the same price as one. I took my son-in-law back with me, and after we were satisfied that we could build the plane, purchased it and rented a small Ryder truck to bring it home to Northern CA. Unfortunately for me, he was promoted shortly after that and only worked on the plane for about 10 hours. My reason for going to the 601XL was because of my uncertainty regarding my future Medical status and not knowing for a certainty whether I could get the HDS registered as an LSA, and the lure of being able to put a Corvair engine in the XL with its larger wing surface/flaps. The HDS only offered Subaru and VW as alternates to the very expensive/high maintenance/low TBO of the Rotax ULS. The Jabiru 3300 was 'off in the future' at that time, known but not proven. Message: 4 List-Post: krnet@list.krnet.org Date: Fri, 05 May 2006 07:29:34 -0500 From: D F Lively <riksh...@interl.net> Subject: Re: KR> LSA KR-Thanks! To: KRnet <kr...@mylist.net> Message-ID: <445b452e.8e8cf...@interl.net> Content-Type: text/plain; charset=us-ascii Kenny: The Zenith 601 HD is a good choice. I have visited & toured their facility in Mexico MO as it is only about 120 miles from where I live. Additionally it is possible to upgrade it to a higer speed version by just building HDS outer wing panels that will up the max speed to 150 mph. Zenair also offers a class where they will supervise & instruct you on construction techniques in constructing a vertical fin that you can use in your own plane if you wish to continue. In 2002 I think that was about $650 but you would need to check with the on that. Don Lively Burlington IA 52601 ********
