SonexBuilders.net

I dont want to start a flame war either, and I am not building an aerovee, so this is a moot point for me, but I would think the name of the supplier is not as important as the confirmation that it is not a chinese made crankshaft. That would worry me and I would not fly behind any parts that are made in China due to quality issues that have arisen from chinese made parts in the market.

I have not heard of any issues with the Aerovee cranks, and there are quite a few out there flying, so that is a good indicator they are well made and the terminology used of forged steel and nitrided is what you want to hear your crank is made from.
Aerovee parts are zero time parts as well, so they are new, but if you would feel better, you always have the option of taking it to a shop and having it magnafluxed as confirmation. You are the one that has to fly behind it, so you are the one that needs to feel comfortable with it.

SvingenB wrote:Looks good to me. Now if someone can track down who the only major VW racing crankshaft supplier in the world is.

All I know is that they used to get a lot of their stuff from CB performance, that seems to have changed in recent years (cylinder heads are a specific example which where clearly CB but are now Mofoco).
CB would suit the description of a "major VW racing crankshaft supplier" but they are certainly not the only one, Scatt would be another one (probably the best and most expensive), Bugpack would be a third.

I know CB performance does not want to supply parts for use in aero conversions anymore, read the thread here for more info: http://vwaircraftengines.com/viewtopic.php?f=25&t=311, liability seems to be their concern in this matter.
However, perhaps they've got an agreement with Sonex to still sell them some of their parts without labels/serial numbers, as long as the parts cannot be traced back to CB and Sonex therefore assumes full liability (if there is such a thing in experimental aviation).
(Only guessing here)

xray will only show voids or low density areas of a casting or forging. Forgings do not have voids or low density areas due to the process. A steel casting, on the other hand, will have voids due to trapped gasses or non metalics trapped in the molten metal. In a class 4 xray standard, used on steel castings, the voids are acepable as long as they are spherical. Low density areas due to shrinkage are not acceptable. Forging is done to densify the cast structure and cause the grain to follow the shape of the forging. Grain in a casting is not directional. Grain in a forging is like grain in wood. Normally the only forgings/castings that are xrayed, and held to a higher standard, are parts like railroad car wheels and nuclear grade castings, and the few steel parts on a airplane, and you can't afford those. The liabilty responsibility of the producer of a railroad car wheel lasts the life of the wheel. 100% xray of those castings.
This is more than you wanted to know, but the point is, xray won't tell you anything about the quality of a forging. Magnaflux of the surface will find cracks, but a nitrided surface doesn't usually generate cracks. It's a low stress heat treatment and only skin deep. If the supplier didn't have a quality control system in place that backs up the product, he woouldn't be in business very long.

Just saying.

Not more than i needed to know, i'm happy for the lesson thanks :)

vicdelgado9 wrote:I have not heard of any issues with the Aerovee cranks, and there are quite a few out there flying, so that is a good indicator they are well made and the terminology used of forged steel and nitrided is what you want to hear your crank is made from.
Aerovee parts are zero time parts as well, so they are new, but if you would feel better, you always have the option of taking it to a shop and having it magnafluxed as confirmation. You are the one that has to fly behind it, so you are the one that needs to feel comfortable with it.

Good points.

Excellent! I definitely did not know this. Thanks for that post.


Robbie Culver
Sonex 1517
Chicagoland
Tails and Wings complete - finishing fuselage.
N1517S reserved

MichaelFarley56 wrote:

SvingenB wrote: Did you even read the response from Sonex? They care so much they won't even tell us. I find that kind of odd, a bit over the edge care-vise, but that's me.

I did read the response from Sonex and I agree 100% with what Robbie said. If I was Sonex, I wouldn't tell you either. Sonex is the company that pours a lot of money into engine and airframe R&D to make sure they're selling the best product available. Sonex is also the company that would loose revenue if someone else goes out and starts offering their parts at a reduced cost (not that I think someone could; Sonex prices seem very competitve).

No one is pointing a gun to your head, making you buy and use Sonex products. I, and I think I speak for most others on here, have 100% confidence that Sonex is supplying me with the highest quality parts available, and I'm happy letting them do all the leg work to find these parts! If they don't want to offer me their supplier that's fine; I'm thrilled with them as my supplier!

+1!

If I ran an experimental aviation company, and I offered an engine kit, there is no way I would offer up information on how to bypass my company and purchase direct.

Interesting theory, but hardly even of academic interest. What is happening is people rebuilding their Aerovees with Force One hubs, or getting Hummels, GPs or Revmasters from the start (or some factory Jabiru/Rotax/UL). This is why I want a straight answer from Sonex. Do I trust the 2.1 crankshaft, or not?

My view on this is the 2.1 crankshaft "system" is not in principle any different from a Limbach crankshaft (thousands of certified VW based engines flying, lots of them with heavy CS props). There is no secrets to a good working system other than good quality steel and attention to details. The rest has been done by Ferdinand Porsche more than half a century ago. As far as I'm concerned the Force One hub is a solution to a problem that does not even exist, but it comes with a high quality forged crankshaft, a known entity, and the reliability is proven to be 100%

This is my engine, not Sonex. I am the one who shall know who makes the parts, not Sonex. This is experimental aviation, not a silly competition in "who put most blind trust in the vendor". If Sonex were to assemble the engines themselves, this would be different, but this is a moot point, since they don't.

Anyway, the 2.1 crankshaft also has a 100% reliability record as far as I can figure. Since it is a custom made and very specialized part, it is highly unlikely Sonex would change manufacturer, making this a refined product. All bets are this is an OK part. It just would be nice with a little more knowing and a little less betting.