SonexBuilders.net

I'm probably opening up a can of worms here but I like to explore all possible engine choices for my Onex and I will admit upfront my ignorence on the subject.
I know the first thing everyone will hit me with is weight.The Aerovee/Revmaster/Great plains all weigh in at around 160lbs and produce 80/85 hp for a power loading of around 11.25lbs/hp.
The 0-200 weighs in at around 215lbs http://www.tcmlink.com/EngSpecSheetDocs/O200B.pdf and produces 100 hp for a higher power loading of 9 lbs/hp.
Other examples of single seaters in the Onex weight category and lower ,that are built around the 0-200 are all of War Aircraft Replicas such as there P51,Hawker Sea Fury and F-4U Corsair all with a gross weight of 900 lbs the CP80 Zephyr GW840 ,Cassutt IIIM GW 850 ,SR1 Snoshoo GW 760 and the Taylor Titch GW760,for a power loading of 7.6
Why the 0-200 over the v-dub's .Keep in mind that the Onex is stressed for aerobatics.
Forums are filled with storys about the shortcomings of the vw's .Crankshafts breaking,propeller hubs separating etc. .Maybe a lot of mis-information based on a lot of false assumptions.Andy Walker mentioned he has chosen the Jabiru over the Aerovee because he doesn't want to spend his time tinkering with the VW.A valid argument. In other forums I belong to there is the doubt that any VW engine co. out there produces an engine that will run for more than a couple hundred hours before it needs a tear down.True or false?(none of them give a TBO)
I do know however that the 0-200 has an impeccable track record.We have all flown behind one and never gave reliability a second thought.0-200 with 400 hrs left on them can be had for the price of a Revmaster .As a homebuilder I can rebuild the 0-200 myself.There is currently advertised in my most recent RAA magazine a running 0-200 with accessories and 2000 hrs on it for $4000 cdn.What will sell quicker,a Onex with an aerovee or one with a Continental 0-200?
So why have only a few out of hundreds chosen the 0-200 for there sonex's :?: and why should you or I not choose it for our Onex?
If money were no object I would choose the UL260i,96hp ,158lbs hands down but money is an object,but so is peace of mind.

As I see it, it's not a weight penalty that just affects performance, it's structural.

Sonex has set a 200 lb firewall forward weight limit. I'm not sure who has added an 0-200 to their Sonex but what have they done to strengthen it? I like the motor but I would not step into an 0-200 powered Sonex... :shock:

N111YX wrote:As I see it, it's not a weight penalty that just affects performance, it's structural.

Sonex has set a 200 lb firewall forward weight limit. I'm not sure who has added an 0-200 to their Sonex but what have they done to strengthen it? I like the motor but I would not step into an 0-200 powered Sonex... :shock:

Thanks,well now I know :( .As to other sonex with 0-200 I only did a cursory search on the internet eaachapter486.com - Weblinks
http://www.eaachapter486.com/index.php? ... m...view... - CachedThe Sonex is the ideal Sport Pilot Aircraft with its simple construction, affordable price, ... It is powered by the Continental 0-200, 100 H.P. engine. ... and did not go to the said site just took what I read on the google page as gospel.My bad :oops:

What I find confusing is the fact that Sonex would design a plane with this type of limitation.Was it just a way to assure the sale of their own engines? In most other homebuilts you read about builders are always sticking the biggest engine they can afford on their planes ,just making sure that the weight and balance falls in the envelope when all is said and done.Some achieve it by moving the seats back a couple inches.some by moving the battery behind the seat.So this would imply that the structural integrity of the sonex firewall is such that it can't withstand the greater weight .It's only 20 extra HP or 2.75lbs/extra HP.
Oh well it was a fun idea for a while.

As you consider adding 50-60 lbs of engine to the nose of your Onex, don't forget the additional weight of a stronger motor mount and the weight you will need in the tail to keep the CG in the proper location. An O-200 on a Sonex isn't a fair comparison. Heavy planes fly like pigs. Also don't expect your modified plane to have good resale value. May not be easy to insure either?

My opinion....bad idea.

People have fitted the Corvair engines (about 210lb) in Sonex aircraft, and they seem to do okay. Lighter is always better of course, but I think you could get away with an O-200. It's going to make the airplane a bit porky and eat seriously into your useful load (unless you certify to some scary number), but it probably won't be unsafe unless you start doing a lot of aerobatics or overloading it. It does seem like the factory engine options are better suited to the airframe, but it's all up to you...one of the great things about E-AB aircraft...

Andy Walker wrote:People have fitted the Corvair engines (about 210lb) in Sonex aircraft, and they seem to do okay. Lighter is always better of course, but I think you could get away with an O-200. It's going to make the airplane a bit porky and eat seriously into your useful load (unless you certify to some scary number), but it probably won't be unsafe unless you start doing a lot of aerobatics or overloading it. It does seem like the factory engine options are better suited to the airframe, but it's all up to you...one of the great things about E-AB aircraft...

Great Andy ,I get knocked down and you come along and give me false hope :? The more I look at the UL260i the more I wish I had a lot of money.

Here is something Andy said that you need to focus on....."Lighter is always better of course".

Mike53 wrote:Sonex has set a 200 lb firewall forward weight limit.
What I find confusing is the fact that Sonex would design a plane with this type of limitation.

Heavy airplanes fly lousy! They aren't fun and they aren't safe.

radfordc wrote:

Mike53 wrote:Sonex has set a 200 lb firewall forward weight limit.
What I find confusing is the fact that Sonex would design a plane with this type of limitation.

Heavy airplanes fly lousy! They aren't fun and they aren't safe.

I whole heartedly agree if you are strictly talking about adding weight without increasing Horsepower.By hanging a 100 HP engine we have indeed added weight but we have increased the power to weight ratio from 11.25 lbs/hp
to 9lbs/hp.A Supermarine Spitfire has a power to weight ratio of 3.46 lbs/hp .I don't know how safe it was to fly but I'm quit certain it would be a lot of fun :mrgreen:

You're assuming the Aerovee Onex will always fly at gross weight....but probably not. I think the numbers will look more like this:

Aerovee/Onex 600, 200 pilot, 60 fuel = 860/80 = 10.75 lb/hp

O-200/Onex 700, 200 pilot, 60 fuel = 960/100 = 9.6 lb/hp

I'll bet the 100 lb lighter plane will fly better.