Need advice - which is easier to build? Zenith 650 or RV-9A?

They should be about the same in complexity.  I did notice that the Zenith uses blind rivets ("pull" rivets) and that may make it easier to build.  However, as a structural engineer I have some reservations about the safety of blind rivets in aircraft structure.  The RV uses solid "bucked" rivets so you need a good bucking bar and rivet gun set.   Solid rivets are better structurally and they do take a little more time than pulled rivets, but you end up with a better airframe overall.  

Thanks Joanne.

Anh

Anh:

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Joanne, you state that solid rivets are stronger structurally, and I agree.  But don't good designers compensate for rivet strength by adjusting the rivet spacing?  As long as the rivets used are certified to certain limits and specifications, and the rivets are installed to the designer's requirements, wouldn't either type of rivet provide a good quality of construction?

Ried

It is usually better to adjust for the difference in strength by adjusting the rivet size.  Rivet spacing is fairly "standardized" by having them at edge margin plus one-half the rivet diameter.  The exception is for flush head which have a minimum spacing of .5 (for tooling). 

The real issue with blinds isn't so much the static strength it is the fatigue properties.  WIth the type of blind fasteners used in these homebuilts, they have no established fatigue properties.  They are usually a self-plugging blind rivet that has a friction locked stem.  After a few years getting beaten and banged around these fasteners could lose their friction lock on the stem  Once the stem is gone the fastener will continue to loosen rather quickly and the fatigue life of the joint can be considered zero.  Fatigue is STILL a factor even on these small airplanes.

Back to the original question.

All 2 place slow build RVs will take about 2000 hours to build for a first time builder. You will spend about $2k on tools. Assuming all new  components, a day vfr RV will set you back about $55k. A glass panel, custom paint, full house interior, CS prop, IO360 will come in over $85k. Van's Preview Plans or builder's instructions, while thorough, assume you the builder is getting the hang of building an airplane as you progress through the sub-assemblies. Therefore the instructions become more terse by the time you're finishing the wings. It's not quite to the "Assemble fuselage per Drawings 30-40" stage but you should know by now that a #40 drill is the one to use with AN3 rivets.

The Zenith planes assemble quicker because of the use of structural pulled rivets. I attended Mr. Heinz's presentation at OSH a few years ago and I came away convinced that his pulled rivet is just as stout as a solid rivet for this application. The tool list is shorter and therefore fewer $$$$. All other things like the cost of aluminum and aircraft engines being equal, you'll still be into a CH for about $45-50k. The CH book  has little check boxes in the margins for tasks completed. Nice touch.

It's up to you to decide on which one looks better and fits your mission profile.

Thanks Steve for the great advice.  It's about how beginner friendly the kits are for me...I just dread not completing the project and waste money.  I went to an LSA fly-in last weekend and got to look at an RV-8 and talked to a couple CH 601 builders (alas, their planes were not there).  Thanks again.  

From the avdel website.  The AVEX series are considerd to be a "non-structural" rivet.   This means that they should not be used to hold load bearing parts together.  They can be used to hold nutplates, close out panels and structure where there is another defined loadpath.

http://www.avdelusallc.com/products/avex.shtml

Anh;

I'm glad you posted your question to this forum. Your question is the kind that really gets people to thinking about why they choose the path they have chosen when they are building an aircraft. It is a good question, because it has many different parameters to think about.

Many years ago, I was asking myself a very similar question to yours.  For me it was the RV-6A vs. CH601HDS, back in the mid-nineties.  I chose the CH601HDS, for lower tool costs and to take advantage of the blind rivet technology. Please be aware that I have worked with both blind and solid rivets - I am scratch building and built my own spar using solid rivets. It was a very enjoyable part of the project but made me happy I'd gone with blind rivets for the rest of the plane. You can pull blind rivets at amazing speed compared to solid rivets.

Blind rivets are a legitimate aviation fastener, and the ones used in the Zenith products are aviation rivets with a certified shear limit of over 238lbs. Other kit manufacturers are using aviation blind rivets now as well: The Van's RV-12, the Murphy product line, and of course, many of the sport-pilot and ultralight aircraft use blind rivets in all sorts of structural places. Commercially, EADS Socata uses blind rivets in their small aluminum aircraft. One of my very favorite, the TB-9, uses blind pull rivets in it's airframe: http://en.wikipedia.org/wiki/Socata_TB

I wanted to give you one more parameter to consider when choosing a kit: I stopped construction when my children entered high school, and have been working to restart construction of my aircraft now that they have left home. I will have to re-orient myself to the style and technology of the kit vendor in order to pick up where I left off and resume. The simplicity of the design is a huge asset to me in continuing with the construction project where I left off. Plus, even though the 601HDS is no longer sold, I have many friends and mailing lists and resources to call upon as I restart, not to mention the kit vendor, Zenithair, who offers excellent support to all their builders.

Please - come back to us and tell us what decision you make and talk out to us how it goes. I think we are all always interested in hearing your thoughts and experiences you have as you seek to build your own aircraft. 

Best of luck with your choice - either one of these products are spectacular projects that will yield a solid aircraft with wonderful flying qualities.

JKB

Thanks James.  I'm leaning towards the CH 650 due to simplicity and ease of construction.  I talked to some guys that do builder assist and they told me that a CH650 can be built in 500-700 hours.  Originally, I wanted to build the RV-12 but I had to get build it with the avionics and Rotax as it is an E-LSA, and that was going to cost a bundle.  In addition, I can start the CH 650 for $375 with the rudder starter kit; I'm going build the rudder over the winter...brrr..in New England.  I'm planning to buy sub-kits as I go.   

Thanks again, Anh

: Just for the record the Zenith  HDS  is still sold .Its listed on the Zenith site under early models .Always thought it was a great model. Your advice is very good one can not deal with better people than Zenith and their plans are easy to understand.

Thank You