Sonex turning radius
Posted: Mon Mar 12, 2018 8:07 pm
by lstinthot
I am entertaining the toe brakes right now. I am looking at what the turning radius is for the Sonex. Has anyone measured the turning radius? Our airport does not have a full length taxi along with a handful of others around here. How often does someone have to get out to pick up their plane to turn it around? Looking through the past forums it just references the turning radius as “fairly tight”. What is the most narrow airport people are able to turn around in?
MIke
Re: Sonex turning radius
Posted: Mon Mar 12, 2018 9:00 pm
by EdW
With toe brakes, you should be able to make an (almost) locked wheel turn, which should give you plenty of room on a normal runway. Not much more than wingspan-width.
Ed
Re: Sonex turning radius
Posted: Mon Mar 12, 2018 9:01 pm
by kmacht
Never had a problem with the turning radius with regular brakes but if you are installing toe brakes for a tighter radius you will need a full swivel tail wheel as well.
https://www.google.com/amp/s/flyboyacce … guide/amp/
Keith
#554
Re: Sonex turning radius
Posted: Mon Mar 12, 2018 9:38 pm
by EdW
Yeah, hadn’t considered that. I was thinking a castering nose wheel.
Ed
Re: Sonex turning radius
Posted: Mon Mar 12, 2018 10:54 pm
by SonexN76ET
With no toe brakes but with Tricycle gear I can easily do a 180 on a 40 foot wide runway.
Jake
Re: Sonex turning radius
Posted: Mon Mar 12, 2018 11:07 pm
by daleandee
lstinthot wrote:Has anyone measured the turning radius? … What is the most narrow airport people are able to turn around in?
Hi Mike,
I replied earlier but it hasn’t shown up yet. For a tail dragger the answer is 50 feet. You can see it here at the very beginning of this video where I do a 180º turn on a 60 foot wide runway:
https://www.youtube.com/watch?v=1VP7UYEqQ-g
Again, you can see Tony Spicer display the same turning radius on his turf runway before take off (at the 23:00 mark):
https://youtu.be/oP2P5XduWmQ?t=1380
Hope this helps …
Dale Williams
N319WF @ 6J2
Myunn - “daughter of Cleanex”
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
Signature Finish 2200 Paint Job
171.9 hours / Status - Flying
Member # 109 - Florida Sonex Association
Sonex turning radius
Posted: Tue Mar 13, 2018 1:01 am
by caveman370
Hi,
Myself ( Mike) and John Gillis have the Flyboy accessory’ swivel tail wheel. It’s awesome with toe brakes. Pivot on either main if you need to
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Re: Sonex turning radius
Posted: Tue Mar 13, 2018 8:16 am
by peter anson
kmacht wrote:Never had a problem with the turning radius with regular brakes but if you are installing toe brakes for a tighter radius you will need a full swivel tail wheel as well.
https://www.google.com/amp/s/flyboyacce … guide/amp/
Keith
#554
Well, strictly speaking, Keith is right of course, but I have independent brakes and a non-swivel tail wheel and my Sonex has enough grunt to drag the tail wheel around a tight circle, even on sealed surfaces. It’s not great for the tyre of course, and not as controllable as a full swivel tail wheel. Have to admit I only do it occasionally and normally only on unsealed surfaces.
Peter
Re: Sonex turning radius
Posted: Tue Mar 13, 2018 10:59 am
by Gordon
Full Swivel Tail wheel
I am also using the full swivel tailwheel from Flyboys (the same type I used on my RV-7). This is a quality product and Blake and Vince Frazier are great to work with. I am also using a 6" tailwheel and 5:00x5 tires (same as the RV’s) along with Hegar hydraulic heel brakes with the Sonex style hydraulic brake cylinders.
I would sooner have toe brakes but that requires welding up something and getting the geometry just right. The Hegar heel brakes (Aircraft Spruce) simply bolt to the floor ( I riveted up some special brackets for them) so the installation was quite simple and easy.
I learned to fly in the 60’s with heel brakes so I don’t find them to be a particular “hardship”.
Note…the tail DOES sit a bit higher (2 1/2") so the angle of attack is less in a 3 point attitude.
Gordon…Onex…Hummel 2400
Re: Sonex turning radius
Posted: Tue Mar 13, 2018 7:25 pm
by lstinthot
I just received an email from Flyboys about their full swivel tail wheel. It looks appealing. They did mention the higher stance for the 6" version and recommend going with the bigger front wheels if ordering the 6" wheel. What would be the down side to having more visibility over the front with the higher tail? Possible nose over easier?
Mike
Re: Sonex turning radius
Posted: Tue Mar 13, 2018 8:17 pm
by kmacht
Less angle of attack when doing a 3 point landing. A higher tail wheel will make it a little more difficult to be in a full stall right when touching down since the wings will be at less of an angle. May not make a big difference, don’t know until you try it.
Keith
#554
Re: Sonex turning radius
Posted: Tue Mar 13, 2018 11:13 pm
by sonex892.
kmacht wrote:Less angle of attack when doing a 3 point landing. A higher tail wheel will make it a little more difficult to be in a full stall right when touching down since the wings will be at less of an angle. May not make a big difference, don’t know until you try it.
Keith
#554
I’m not sure even a standard tailwheel Sonex is fully stalled in the 3 point attitude. I have a homemade fully swivelling tailwheel with a pneumatic 6" Peter Anson type tailwheel. The noticeable differences are, better visibility lower noise while taxying and of course being able to spin around on a main wheel.
Re: Sonex turning radius
Posted: Wed Mar 14, 2018 9:08 am
by Sonerai13
sonex892. wrote:
kmacht wrote:Less angle of attack when doing a 3 point landing. A higher tail wheel will make it a little more difficult to be in a full stall right when touching down since the wings will be at less of an angle. May not make a big difference, don’t know until you try it.
I’m not sure even a standard tailwheel Sonex is fully stalled in the 3 point attitude.
A Sonex/Onex/Xenos is nowhere near stall angle of attack when sitting at a 3-point deck angle. In fact, most tailwheel airplanes are not near a stall in the 3-point attitude. But it’s especially true in the Sonex line. That’s why it’s important to recognize the 3-point attitude visually, so that you can find that attitude and fly the plane onto the runway. If you attempt to “stall” the plane on landing, your tailwheel will be about 3 feet lower than the main wheels when it touches the ground. That will make for a rather abrupt arrival rather than a 3-point landing.
Re: Sonex turning radius
Posted: Wed Mar 14, 2018 10:05 am
by Gordon
Flyboy Full Swivel Stance
Mike…the problem with the higher tail stance is not a “nose over” issue. The problem is when doing a full stall 3 point landing…you hit the tail wheel first…then the mains. It’s not that big a deal, both my RV-6 and RV-7 would hit the tail wheel first… a split second before the mains. I have 800 hours in taildragger RV’s and can confirm this is not a problem. The early RV-4’s were the worst for that until Van’s came out with 3" longer main gear legs to combat that problem.
The “up side” as you mentioned is that you have a bit better view over the nose while taxing.
Gordon…Onex…Hummel 2400
Re: Sonex turning radius
Posted: Wed Mar 14, 2018 4:01 pm
by lutorm
The turn radius depends on how many G’s you pull… 
Re: Sonex turning radius
Posted: Wed Mar 14, 2018 4:21 pm
by GordonTurner
Ahhh. Closing in on the answer. Turn radius is a function of TAS and G.
Re: Sonex turning radius
Posted: Wed Mar 14, 2018 4:55 pm
by Waiex 49
I have added the Sonex disc brakes with toe pedals and independent left/right master cylinders. This was, in my opinion, a major improvement over the stock “pull on the lever” drum brake system with no independent brakes the “direct steering” stock setup.
While the Sonex disc brake kit has numerous shortcomings, required several modifications and was a general pain to install, I find the Sonex disc brakes actually work pretty well and the plane benefits from having independent left and right brakes and this can serve to tighten up the turning radius even with the direct drive tail wheel.
I now have the 6" full-swivel tail wheel setup from Fly Boy Accessories. The full swivel tail wheel is really nice and allows the plane to pretty much pivot on the main gear for very tight turns on the ground.
I already had a 6" tail wheel on my plane so that is what I went with when ordering up from Fly Boy Accessories. It really does put the tail up higher and lowers the nose. I can get away with this because my titanium tail wheel rod is bent from years of abuse and this lowers the tail back down a bit.
If you are interested in going this route, I would NOT recommend going with the 6" tail wheel. The 6" wheel gives too much lift for the tail and I believe the 4" setup would be much better suited for the Sonex / Waiex airframes. Fly Boys has a very nice 4" full swivel tail wheel setup for the Sonex.
I am very glad I upgraded the brakes and went to a full swivel tail wheel on my Waiex. While the Sonex disc brake kit sucks pretty badly, I made it work. If I had it to do over again I’d probably get wheels/brakes from another vendor. Having independent left/right brakes is really, really nice and worth the effort. I used the Hegar master cylinders from Spruce and toe brake pedals I bought off the forum. The tail wheel from Fly Boys Accessories is very nicely made and worth the extra $$.
Just my 2 cents worth. Hope to see you all at Osh!
Fly safe,
Don Bowen
The Outlaw Viking Waiex N49YX
Re: Sonex turning radius
Posted: Thu Mar 15, 2018 7:50 pm
by lstinthot
Thanks for all the responses. I like the idea of toe brakes, just need to determine if I want to take the weight penalty as I am already going to be a bit on the heavy side. Just one more thing to add 
Sonex turning radius
Posted: Sun Mar 18, 2018 9:20 am
by drPete
Don,
I too have the Flyboys tail wheel but haven’t committed to the installation on my XenosB yet.
- Any weight & balance issues with the heavier assembly?
- Any appreciable tracking/wear issues with the slight difference in angle between the FB and Sonex tail wheel sockets?
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