SonexAus – Tips and Tricks Feel free to add any ideas, tips, tricks or items of interest.
Dimpling using the Cleaveland Tools DIENQ set This is an alternative to the Sonex super simple dimple die set.
Fatigue of metal aircraft All metal aircraft are subject to "fatigue" the failure of components under repeated loading where the loads are not normally high enough to cause failure. Fatigue failures of home-built aircraft are not common because most of us don’t do many hours and we don’t subject our aircraft to military type flying. However, I have seen several examples of fatigue failures on Sonexes, and even experienced one myself. Inspection of possible fatigue areas is not difficult and costs almost nothing. In the linked article I have tried to describe why and how fatigue occurs and where to check on your Sonex. – Peter Anson
Fuel vent safety valve Dynamic Propeller Balancing In addition to the above linked article by me, here’s a link to a more informed article written by Brian Rebbechi. Propeller Balancing – Airsport Winter 2016.pdf
Simple Park Brake idea Cockpit Noise Fitting fire-sleeve Economical Temperature Sensors I made my own thermocouples (it’s easy) and tested them against a calibrated temperature source. They were accurate to within 1ºC at temperatures up to 300ºC. Follow link for details.
Improved seat comfort
This is a fairly neat little light-weight (so you can carry one on a trip) lever jack that works with Tracy O’Brien axles as is. For use with Sonex axles, an attachable hard point is also available. I will be selling these, but have included complete jack drawings on my web site (follow link) in case you want to make your own.
File Resources for scratch builders
From our sister club in the UK:
Stuart Garton, building a Waiex here in the UK, has done some research into the ‘chisel’ type rivets Sonex have been supplying for a year or so. Older kits have the round head rivets, newer kits will have the replacement rivets that have succeded the chisel type, neither affected by the problems Stuart describes, but if you have any chisel type rivets his research reported below will be of great help:
Sonex Pulled Rivets
Sonex’s pulled rivet supplier recently changed their tooling and in turn the design of the mandrels used across the range of pulled rivets supplied by Sonex with their aircraft kits.
Much has been written and debated on the various forums about the change in rivets and their integrity, strength and functionality which has led Sonex to source a new supplier and make available, for an appropriate fee, a replacement rivet kit. I therefore have no intention of regurgitating what has already been said, but feel free to go off and read at your leisure should you have a few hours to spare from your building time! The purpose of the following is just to share my experiences and testing which has enabled me to use the new anvil headed mandrel rivets with a very good success rate.
I have to say I am not an engineer so all my experimentation was not carried out with any scientific approach, just curiosity to try and work out why changing the head of the mandrel was causing trouble and I am sure the more technically minded will have cause to question further my findings.
There seemed to be three problems arising when using the new rivets.
Firstly, the mandrels
would break off proud of the rivet head leaving an annoying projection that had to be ground off with a "Dremel" or similar. Secondly, the mandrel would pull clean through the rivet leaving a gaping hole down the centre which whilst the factory insist has no detriment to the integrity of the rivet, does not look good and you may have a job persuading your Inspector that the rivet is sound and does not need resetting. Thirdly, and I have to say this has not happened with any of my rivets but was widely reported on the forums, is that mandrel can fall out the back of the set rivet leading to the same issues as above and a loose mandrel head floating around your new aircraft!
I started by setting a number CCP42 rivets and then cutting/grinding them open to see inside. I tried this with both holes of 1/8" and #30 diameter. It was immediately apparent that my newly acquired stock of #30 drill bits are going to be of little use. The bigger diameter of the #30 hole seemed to be the primary cause of the problem as regardless of whether the rivet was pulled by hand or at various pressures with the air riveter it allowed the mandrel to pull too far through the rivet resulting in either, in the worst case pulling all the way through and out, or just breaking off proud.
The 1/8th holes gave much better results, especially if pulled slowly and with the absolute minimum air pressure.
Having come to the conclusion that the hole size is the critical element in achieving a successful rivet I turned my attention to the CCC rivets used on the wing leading edge skins or in my case, as I am a glutton for punishment, on all skins. I initially tried the recommend method of #40 pilot holes, up drilled to #32 before dimpling with the Sonex simple dimple die.
I found a good number of the test rivets broke the mandrel proud of the skin and would require grinding off. I also noticed that the head of the rivet was set just below the skin surface, about 10thou when measured. I tried shimming the male dimple die, initially 5thou and then 10thou (very technically held in place with a dab of super glue) which left a perfectly flush rivet once pulled. The side effect of shimming the die was to reduce the finished hole diameter.
The #32 hole was opened up less by the dimpling process, so much so that the rivet would not push into the hole by hand and I made a simple tool (aluminium bar with a hole drilled centrally up one end and the other inserted into a wooden file handle) to push the rivet all the way home before pulling.
I have now riveted the flap and aileron skins with this method and only had a very small number of rivets (less than 10) that broke off proud and required any grinding.
To conclude, the hole size with both types of rivet (CCP and CCC) is critical to successful riveting. Therefore, don’t use #30 drill bits, use 1/8th, after all the rivets are 1/8th rivets and carefully check your Sonex simple dimple die to ensure it is not "over dimpling" which could well save you a few hours of carefully grinding.
Tips from the American Sonex Association
Click here to go to their website for Builders Tips Builders Tips
A guide to dimpling with the Simple Dimple Die by Peter Henry
Interesting discussion on EGT’s and CHT’s by SAVVY (Sound required)
Drilling for wing Spar Bolts
Aircraft Performance by Kerry Fores
Hinge drilling made easy by Peter Henry
Weight reduction How to reduce the weight of your Sonex by up to 40 KG’s without effecting its structual strength. By Adrian Clout.
Interesting discussion on controlling mixture by SAVVY (Quite long and sound required)
Control Stick Mods Richo’s spar tunnel contact and stick slop on control horn fixes
Note Kip Laurie no longer supplies these (since 2013) Tailwheel bracket available: From Michael De Feyter:
Kip Laurie (Waiex #0082, N111YX) has designed a new tail wheel bracket for the Sonex/Waiex to fit the larger Vans lightweight tail wheel (http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1314042541-454-123&browse=am&product=LW-t-wheel).
Kip’s posted a threadon Sonexbuilders.net about his bracket, you can read more about it there: