This guy has very little use for Zenith Aircraft... And apparently me too.

This posting that was on the internet was forwarded to me by several friends.......


On the "801"

“This is an accident waiting to happen. The motor mount is incorrectly designed with un triangulated bays and bent tubes in tension and compression. The firewall forward weight is at least 450 pounds aluminum block or no aluminum block. No mention is made of beefing up the fuselage to take the vastly increased bending loads during landing and high G turns not to mention the increased bending loads on the wing spars. Zenairs are not over designed to begin with having very thin skins.

"The fuel burn is better then expected though and I am presently confirming the JPI 450 for accuracy. Cruise @ 11,000 msl is producing 5.9 0 -6.3 gallons an hour."

The numbers quoted above shows a lack of understanding about engine engineering in general. The fuel burn quoted at 6 gallons an hour or 37 pounds an hour means the engine is only generating 83 HP giving it the benefit of a BSFC number of .45. In the unlikely event the BSFC is as low as .40 the HP then would be 93 HP at the absolute maximum. Now you have a 450 pound firewall forward weight putting out 93 HP at cruise.

Something is seriously wrong.

"The numbers I am shooting for are one pound of engine weight for each horsepower and a small total engine profile that will fit in most airframes."

What he is saying here is he things he is going to get 350 to 400 HP with a 1.43:1 PSRU ratio. With a 2600 RPM prop that is 3700 engine RPM. No way is that going to happen.

This person is totally clueless.

I am really worried here. Probably one of the most dangerous airplanes I have seen in a very long time.

Paul Lamar”

I don't know who this "person" is or what his qualifications, but..

I am compelled to answer his hatchet job on every topic.

My project is a one of a kind. I had no group, forum or any other source to go to during the design, and test flying of my experimental aircraft, so all the calculations, fabrications and installations are a one off and done to the best of my ability using past life experiences from fabricating stuff on race boats, cars and god only knows whatever I have modified in earlier years.

I built my plane, 3000 + hours of MY time. I didn't but a half built one, or a completed one to use a test bed for my powerplant. I have been flying for almost 30 years and owned several other planes.

My experimental plane has been flying for 5 years and 300 hours. Been flown in air from 97f to -37f. Has over 500 landing, been flown from JAC, 6430 msl to 18,000 feet, full throttle, !! over a couple of dozen times to test it for strength. Been flown in all other power settings to comfirm and quantify data. Tested to +3.5g's to - 2.5 g's. Flown to OSH and back... not trucked there as others seem to do to display their creations.

My responses..

1- When is this " accident" going to happen ??

2- The mount is designed by me using triangulation, just go to my web site and look at the pics.

3- There are NO bent tubes in my mount. there are intersecting angles but that happens on ALL mounts. At those intersections the area is beefed up internally. Just because you can't see it doesn't mean crap.

4- I know EXACTLY what it weighs. I don't guess like he seems to. And it is less then his "estimation"

5- Of course I beefed up the airframe as I built it. Just because I didn't state that on my website should not give him a pass at a free shot.

6- Zenith Aircraft seem to be an "issue" to him. Mine has twice the "suggested" HP and still has not broken in half.

7- The plane has so much power that at cruise I can throttle back to ALOT.. A 801 has alot of aerodynamic drag. I can run 90@ 6.4 GPH or 110@ 17 GPH. The plane hits a brick wall so why burn three times the fuel to go a little faster. If I wanted to go fast I would have built another type plane. You would think a guy like him could draw a simple conclusion.

8- I have probably built, raced and tested more engines hen he can dream about.

9- BSFC of .45 ??? Jeez. I would be embarrased to tune a motor that rich.

10- Nothing is " seriously wrong"............. I am seriously throttled back.

11- The motor is capable of 600 + Hp in different trim. ie, different redrive ratio, different intake design, etc. The motor will not gain any more weight by changing componants, so 350-400 Hp is a no brainer.. On MY plane I purposely stayed with 1.43-1 because it for sure doen not need any more power.

12- Where did he get the 3700 RPM # from ? I turn the motor alot higher then that on take off. Yeah, the prop is kinda noisy but nothing worse then what noise a seaplane makes with a large diameter prop.

13- """ Totally Clueless""" Ya wanna bet..

And in closing all I can add is
" I am really worried here. Probably one of the most dangerous airplanes I have seen in a very long time. "

Geez... Where was he 5 years and 300 hours ago ??????.

Ben Haas.

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Replies to This Discussion


There are all kinds of folks in the world. This fellow seems less interested in helping you then proving he is an expert at something. Don’t take it personally. Your airplane and experience speak for themselves.

Learning and improving is a useful goal. Sometimes it is useful to examine someone critique to see if there is something to learn from it no mater what motivated the person to make the critique – sometimes not.

Don’t feel defensive. The person criticizing your creation may have spotty credentials and/or an ego problem. Even if this person has training in the field of airplane design, folks with training in the field are full of dogma about how a given task “should be done” or how you “should fly or not fly your airplane”. I find that odd and in conflict with what we see in the real world. One only needs to attend an air show to see wild variations in things that fly and ways to fly them.

Learn what you can. Apply it to your project. Be safe, have fun.

Dear Ben, You can't fix stupid, so I wouldn't concern myself over such commentary we know what you can and have done and your vindication is in the reality of history in your logbook!

Hi Ben,

He is just another internet wannabe pilot. Probably wouldn't know s%#t from shinola.

It is too bad that Delta Hawk didn't think better of ytou. They would have had something more to show than just another engine on a table.

Nice looking job, something to be proud of.


Dan Stanton


This is "experimental" aviation, but there are a lot of people on the internet trashing others' experimentation.  especially in the area of auto conversions. 

If someone, like you, is successful at something they themselves have been trying to perfect for many years they can get real nasty.  I sat through his presentation on the Mazda Wankel engine about ten years ago. It seemed to have great potential, but I don't think there are very many flying.

P.S. enjoyed chatting with you at OSH.  You have created an impressive plane.

I've posted a few times on this site that I'm no fan of auto conversions; but there are guys out there like Ben that are making them work. From reading Mr. Lamar's post it seems he may be a bit confused on the difference of performance of an engine at ground level as opposed to attitude (fuel consumption/hp). I'm amazed he would make such statements; "accident waiting to happen"; after 5 years and 300 hours of the plane flying. That statement doesn't give him much creditability. Also "vastly increased bending loads during landing". Unless Ben is slamming the front end on ALL landings the compression strenght of 4130 tubing (if that's whats used) is much greater than what is being delivered to it on a normal landing. Taking into account load absorbtion from the main gear, the tires. AH well; it was exciting reading considering the slow start day here at school.


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