SonexBuilders.net

There is an excellent article in the May issue of Flyer magazine (dunno if that goes outside of the UK) by Francis Donaldson about how the Sonex got to be approved in the UK. You may know that in the UK it is like drawing blood from a stone to get a type approved - which is both good and bad depending on your viewpoint.

Francis Donaldson is the Chief Engineer at the UK Light Aircraft Association and gets to test fly just about any number of permit planes. He's very well respected for his work and attention to detail and by all accounts a pretty decent bloke although I have never met him.

Anyway, overall a very positive review and it noted some interesting modifications required for the LAA, for example improving the longitudinal stability with flaps down by using an automatic elevator tab connected to the flap system and noting that with the heavier 3300 jab or Aerovee and dial a trim fitted the level flight stability was far superior to 2200 jab installation without dial a trim fitted. They even fitted a potentiometer to the dial a trim and connected it to the EFIS for a visual bar chart indication of trim. He also noted that he thought the tail wheel version was more stable in the air than the nose wheel version as well as easy to land and being excellent on the ground even without diff brakes.

They quoted some pretty good figures too which I'm pretty sure were test data: Max level speed 156kts & 1160ft/min RoC.

I think the best part was a reference or two to the RV calling it a mini RV at the price of tube and fabric microlight. In the past there was talk of a bit of friction between the LAA and the Monnetts but if this article is anything to go by that hatchet has been well and truly buried. Now all it needs is aerobatic approval like the RVs. Its amazing that there are over 500 RVs in the UK but only a dozen sonex. I think this article may change that number a bit. I know at least one will be added......

Cheers.

Interesting. It's a shame that they have to water down a design that does not exhibit unsafe flying qualities. An "aviator" is supposedly at the helm after all.

I'm happy to see the Sonex grabbing hold in the UK. It should have happend a long time ago...

I dont think they have watered it down really but they have probably reduced pilot workload a bit. LAA would probably argue that it makes it a safer aircraft without suggesting it was a dangerous one in the first place which clearly its not. The mods are pretty minor really.

It also looks like Waiex and Onex are on the way to the UK too! Happy days.
8)

The trim indication on the EFIS is interesting. I've always wondered how (other than just "feel") the Sonex trim system can be accurately set neutral for takeoff, etc. Guess I'll find out when mine flies, LOL.

The UK modifications seem to consist of:

• Flap angle limited to 25 degrees
• Flaps pull up trim tab
• Dial trim is required
• Trim indicator required
• Fibreglass tail tips are required
• Cage under the seat in case it collapses

I have to wonder if many of these modifications are really necessary. Sonex aircraft seem to be able to fly the world over without any of these changes yet for some reason here in the UK our air is different.

I am currently building Sonex 1526 documented here http://kdmiller.unospace.net/mediawiki/index.php?title=Main_Page.

Craig

I don't think it's just the UK, most countries in Europe (under the JAA) are like that.
I'm Belgian but I've lived in Australia for 5 years now. When I started building my Sonex here in Aus, one of my pilot buddies in Belgium immediately was interested in my project and wanted to build his own in Belgium.
Unfortunately the Sonex is not on the approved kit aircraft list in Belgium (forget about scratch building in Belgium), so after months of investigation (he really tried hard) he dismissed his plans of being the first Sonex builder in Belgium and determined that it was just all too hard so instead he decided to build an RV-7, which is on that notorious list.
It was possible, especially because the Sonex flies in other European countries that operate under the JAA, it was just very, very very hard (not worth the trouble).

ccm wrote:The UK modifications seem to consist of:

• Flap angle limited to 25 degrees
• Flaps pull up trim tab
• Dial trim is required
• Trim indicator required
• Fibreglass tail tips are required
• Cage under the seat in case it collapses

I have to wonder if many of these modifications are really necessary. Sonex aircraft seem to be able to fly the world over without any of these changes yet for some reason here in the UK our air is different.

The weirdest one to me is the cage under the seat. Sonex aircraft have been hard landed, pancaked into fields, and endured every other kind of abuse to the seat structure, but to my knowledge none of them has ever collapsed. In fact, in a REALLY hard impact, the under seat cage might just cause more broken metal bits to pierce your bum and break your back! It seems the British authorities are looking only at at the design according to some checklist of criteria, and not the Sonex operational history.