SonexBuilders.net

I need to take off one of my wheels to have a look at a problem with my left brake.
What's the best way to jack up a Sonex, where is the best spot to put the jack on a tail dragger?

Like this bloke did, but on one side...?

tonyr wrote:Like this bloke did, but on one side...?

Hmmm, looks familiar :D

Anyway, that was what I was thinking but perhaps there are better ways? Maybe under the spars?

I believe that is the strongest point on the airframe for jacking. Normally all the landing loads are transmitted through there so its strong enough.
You could make a U bracket out of a couple of bits of angle iron, with slots to fit under the axle retaining bolts.
Then put that on the jack pad and raise it at the axle.
I have Tracey Obrien axles which make jacking it up pretty simple.

Thank you greatly for posting this photo showing a means to jack the Sonex aircraft.
I was out at the hanger today pondering how to do this.
I pretty much came to the same conclusion, but it is nice to see a photo of how it works.

Thanks again,

Don Bowen
Viking Waiex N49YX

I've done it two ways:

- Chock the opposite wheel and the tailwheel (if so equipped).
- Use floor jack or a typical scissor jack with 2x4's to spread the load under the spar tunnel.
- Jack up the plane along the spar tunnel but off the centerline, so the wheel on that side lifts off the ground, but the chocked wheel remains on the ground.

or ( mostly works on a tail wheel airplane):

- Lift up the tail and put a custom sawhorse underneath the spar tunnel.
- Push down on the tail until the wheels come off the ground and the tail wheel touches the ground.
- Put 40 or 50 pounds of "stuff" on the horizontal tail to hold it down. I used a couple of bags of bark mulch.
- I found this process to be a 2-person job.
http://www.mykitlog.com/users/display_l ... 166&row=15

Basic premise: use the spar tunnel and spread the load so you don't punch through the skin.

the problem with jacking up a sonex from the tiedown points on the wings is finding a jack with the right travel. It takes about 8 inches before theres enough lift to raise a wheel. That means you need a bottle jack with a lot of throw that can still be fit under the wing retracted.

I ended up going with a bottle jack I put on a moving dolly with some 2x6 blocks and jack up at the fuse right next the gear leg. Works great.

mike.smith wrote:
Basic premise: use the spar tunnel and spread the load so you don't punch through the skin.

I would add to this note (if going this route) to use the bottom of the longerons at either end of the spar tunnel. The bottom of the spar tunnel between the longerons isn't stiffened by anything more than various pieces of .032 sheet.

I.e. don't put too much pressure in the open space beneath the spar tunnel between the wing attach points. The only piece of strong angle along the spar tunnel is at the top under the seat pan. The wing spars don't touch the floor. Make sure your wood, jack, sawhorse, etc is long or short enough to put the load on the longeron(s).

Rynoth wrote:I would add to this note (if going this route) to use the bottom of the longerons at either end of the spar tunnel. The bottom of the spar tunnel between the longerons isn't stiffened by anything more than various pieces of .032 sheet.

The sawhorse method accomplishes that. And if jacking up only one wheel via the second method, there is not a great deal of load on the bottom of the aircraft. The spar tunnel forms a box beam. It's quite strong. If you look at the construction of the fuselage where it meets the bottom of the firewall, there is much less structure there than at the spar tunnel. I think all the methods here work. Just be smart about how you make contact with the bottom of the aircraft.

Once you do get the wheels off the ground, remove the stock axles, throw them away and fit Tracy O'Brien axles. They extend inboard giving you a small hard point to lift. A small car scissor jack would be suitable then.

Before I fitted the T O'B axles I used to use a saw horse under the wing tie-down points. I'd get under the wing with my shoulders under the spar, lift the wing and then drag the saw-horse under the hard point. It would be a lot easier and safer with two people. If you get it wrong you stand a chance of damaging the wing skin, but I have only ever done it when there was nobody around to help.

I also have a large wooden over-centre stand that picks the whole forward fuselage up on the lower longerons. I built it so I could fit the T O'B axles. It isn't too convenient because I have to take off the cowling and leg fairings to use it, but it's very strong and stable. Would be good if you needed to remove something major like the gear legs or engine mount.

Peter
Sonex 894