sonex trim systems
Posted: Sun Mar 31, 2013 12:58 am
by n502pd
I am wanting to use a simular system to the aeroconversions dial a trim, except I want to utilize the trim tab instead of the springs. Has anyone done this? How did it work out?
Do you feel it is better than, the same as or worse than the spring system attached to the control assembly? What did you use for a trim system setting indicator? thanks! Joe S/N 1510 :?:
Re: sonex trim systems
Posted: Sun Mar 31, 2013 5:33 pm
by kmacht
I have to ask why would you want to do that? The dial a trim system works well and the lever trim system works well. What would be the advantage of combining the two systems. If you hook the trim tab to the dial a trim knob there is no way to see where your trim is set at before taking off. With the dial a trim you can feel the force on the stick to see where it is set. With the lever system you can see where the lever is set.
Keith
Re: sonex trim systems
Posted: Mon Apr 01, 2013 9:30 pm
by n502pd
Well, Kieth, thanks for the reply! I am not really confortable with springs on the controls. Just me. I had flown C172 for many years with its direct system and am very comfortable with it.The trim tab connected to dial trim clone, has an in cockpit indicator on the instrument panel, in direct sight with no fumbling below the panel for a ‘reading’. I like that too. It all uses bowden style cables and a jack screw. it has a crank knob on it so it can be turned quickly, but from what I hear(having not flown Sonex yet) that should not be a real problem. Also, this clone has cost me less than $5 for one of the bowen cables. Thats my story! Thanks again for the comment!
Re: sonex trim systems
Posted: Tue Apr 02, 2013 9:29 am
by kmacht
Do you have any pictures of your setup for an indicator for the dial trim clone? That seemed to always be the biggest drawback of hooking the standard trim tab to the dial a trim crank. If there was an easy way to add an indicator it would probably be usefull to those with even the standard dial a trim system.
Keith
Re: sonex trim systems
Posted: Tue Apr 02, 2013 11:09 am
by n502pd
Hi Keith! I will work up the pictures on my clone. I have not installed it yet as I dont have the spar tunnel and wings complete, and wont be for quite a while yet. But, I can show how it is intended to work.
As far as putting an indicator on the Sonex system, I have nothing to show. Some may not think my idea is sophisticated, but it will function properly. I have not decided just where to mount the indicator…on the pannel or on the glare shield. It will probably be a last minuet decision. You also have to realise that I am sort of a tractor mechanic…I tend to over build things! Maybe some one can use the idea to add an indicator to the Sonex unit.
If you want, send me your private email and I will return the pictures that way. Or, since I am a real nubie here, help me with how to post pictures, if that is even possible.
Thanks for the interest!
Joe
Re: sonex trim systems
Posted: Wed Apr 10, 2013 3:55 pm
by n502pd
Hi Keith, two pictures are susposed to ber available from these url’s. One is of the clone itself, mounted in place of the dial a trim, connecting to the trim tab with an uninstalled bowden cable. the crank handle is too long just now as I have not fittet it to the instrument pannel yet and will be shorter. second pix shows indicator that attaches somewhere to the instrument pannel, probably between a couple of the steam gauges I am using, and will have a some sort of scale behing it as a relati9ve reference to the trim tab position. No springs or anything to rub on the bottom of the seat! We shall see how it goes! Let me know if you can not get the pix to work
Joe, s/n 1510 scratch building TD
Re: sonex trim systems
Posted: Tue May 21, 2013 6:58 am
by dcstrng
Interesting discussion with good options. Other than perhaps more primitive looks, I’ve often wondered why the Wittman pitch trim system isn’t more popular for aircraft like the Sonex with fairly balanced pitch characteristics (or so I’ve read – absolutely NO personal experience). The Sonex dial-a-trim is essentially a more refined (albeit more intricate, as well) version of the Wittman system – works by simply loading the loading the pilot’s pitch control mechanism to the elevator rather than the mechanical gymnastics of adding a trim-tab on the elevator and then running the actuation back to that. The Wittman system simply acts on the control stick itself – even more basic than the Sonex it appears to me.
Inquiring (albeit geriatric) minds want to know… :o
– Larry
Re: sonex trim systems
Posted: Tue May 21, 2013 9:48 am
by daleandee
Personally … I like the plans designed lever trim with a tab on the elevator. I’ve had the “Dial-A-Trim” system and it works but there isn’t a visual way to see where the trim is set. You are correct that it loads the elevator tube as it removes the load from the stick. My biggest concern with the “Dial-A-Trim” system is that if the bolt from the elevator tube to the elevator bell crank were to fail (the odds are extremely unlikely) then you would have no trim to fly the airplane with.
Other advantages of the lever/trim tab are; quick to set, less weight, less money, and fits on the side panel out of the way. A quick glance tells me whether I’m set for take-off and it’s very intuitive to learn how much to move it for different flaps settings and speeds.
Just one man’s humble opinion.
Dale Williams
N319WF @ 6J2
Myunn - “daughter of Cleanex”
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
22:30 hours - Phase One
Status - Flying
Re: sonex trim systems
Posted: Tue May 21, 2013 10:39 pm
by n502pd
I have, since I posted my pix, re-done my trim system to be about 75% lighter and quite a bit smaller. It functions the same way, with the panel mounted indicator. I like it much better than the original…much smaller! Not flight tested for a great while, though. making nose ribs for the wings just now.
Re: sonex trim systems
Posted: Wed May 22, 2013 10:46 am
by dcstrng
daleandee wrote:Personally … I like the plans designed lever trim with a tab on the elevator…
Other advantages of the lever/trim tab are; quick to set, less weight, less money, and fits on the side panel out of the way. A quick glance tells me whether I’m set for take-off…
I’ve seen several builder’s pics and the side-panel mounting certianly appealed to me for its simplicity – but my plans have not yet come so I can only guess how it actually works…
– Larry
Re: sonex trim systems
Posted: Fri May 24, 2013 9:15 am
by onex28
Dale could you post a photo(s) of you installation or direct me to web photos, I’d like to see how you designed/mounted the trim control handle. Thanks.
David
Re: sonex trim systems
Posted: Fri May 24, 2013 6:00 pm
by daleandee
Hi David,
I installed the standard Sonex plans trim system.
http://websites.expercraft.com/daleande … g_id=55209
http://websites.expercraft.com/daleande … g_id=66633
I have read where some builder’s have increased the size of the trim tab slightly. From my flight testing so far I haven’t found a need to do that. But I still have gross weight testing to do.
Dale Williams
N319WF @ 6J2
Myunn - “daughter of Cleanex”
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
22:30 hours - Phase One
Status - Flying
Re: sonex trim systems
Posted: Fri May 24, 2013 10:29 pm
by onex28
Thanks Dale, that helps a lot.
Re: sonex trim systems
Posted: Mon Mar 02, 2015 1:37 pm
by ihab
Hi there,
[ resurrecting an old thread ]
n502pd wrote:I have, since I posted my pix, re-done my trim system to be about 75% lighter and quite a bit smaller. It functions the same way, with the panel mounted indicator.
-
Do you have pictures of your new trim system?
-
Has anyone thought of using a mixture knob as a trim control? It would allow quick, large adjustments; it can be rotated for fine adjustments; and the position should be very clear just by looking or feeling. Though I guess one would have to make a mark on the rod somewhere to indicate the neutral “takeoff” position.
Ihab
Re: sonex trim systems
Posted: Mon Mar 02, 2015 2:54 pm
by n502pd
Let me dig it out of the to do box, as I have not completely installed it yet. Still working on wings. I will post photo too. The bowden cable from the cockpit to the elevator trim tab is per the plans. the indicator is not designed/built yet,but will be connected by another bowden cable to some sort of top of glare shield indicator, mostly because my round gauge panel is full! Might take a day or to to get the pix and post back.
Re: sonex trim systems
Posted: Mon Mar 02, 2015 2:57 pm
by n502pd
I forgot to clarify…my system isnt ‘new’ per se, but just my clone of the original Sonex method. I didnt intend to mislead. The newer and lighter is in reference to my original clone, which was too large for the afore mentioned full panel.
Re: sonex trim systems
Posted: Mon Mar 02, 2015 4:45 pm
by ihab
n502pd wrote:Let me dig it out of the to do box …
Thank you! I look forward to seeing it!
I also wonder, idly, whether some arrangement that uses a reduction gear attached to the main shaft, driving a pointer that could either spin on the same bearing as the shaft or on a separate little bearing beside it, would be a good indicator. It would require a lot of mods to the system but it would probably not be too expensive if Sonex added it to their Dial-a-Trim.
Ihab
Re: sonex trim systems
Posted: Mon Mar 02, 2015 5:06 pm
by Bryan Cotton
I personally see no benefit to being able to move trim quickly. The only lever type trim systems I have flown were in gliders, and due to the small speed range for normal flight there was limited trim authority. The Pawnee had a spring system run by a window crank. It had an indicator but you could also tell where it was whilst on the ground by where the spring put the stick. You don’t really need an indication of trim position while in flight, at least in most GA airplanes. You fly the airplane and trim away pressure.
Re: sonex trim systems
Posted: Mon Mar 02, 2015 5:22 pm
by ihab
Bryan Cotton wrote:I personally see no benefit to being able to move trim quickly.
Fair enough, makes sense.
Bryan Cotton wrote:The Pawnee had a spring system run by a window crank.
Sounds pretty good actually…
Bryan Cotton wrote:You don’t really need an indication of trim position while in flight, at least in most GA airplanes. You fly the airplane and trim away pressure.
In my own flying (which admittedly has been so far only in the C162 “Flycatcher”, with its awful annoying rudder return spring of death from hell, but that’s a rant for another thread…), I have a checklist item to to set takeoff trim. In a pinch, if I forget, I can overpower it and just put the nose where it belongs, but it’s a bit of a scary feeling…
Ihab
Re: sonex trim systems
Posted: Mon Mar 02, 2015 11:47 pm
by radfordc
Bryan Cotton wrote:I personally see no benefit to being able to move trim quickly.
I really liked the lever trim in my old Sonex. When you lowered the flaps there was an immediate strong nose down force. It was nice to be able to trim off most of the pressure with just a quick tug on the lever. Some of the guys with the dial-a-trim just don’t bother since it takes so long to trim.
Re: sonex trim systems
Posted: Mon Mar 02, 2015 11:55 pm
by mike.smith
daleandee wrote:Personally … I like the plans designed lever trim with a tab on the elevator.
Other advantages of the lever/trim tab are; quick to set, less weight, less money, and fits on the side panel out of the way. A quick glance tells me whether I’m set for take-off and it’s very intuitive to learn how much to move it for different flaps settings and speeds.
That goes for me, too. Dirt simple, and works perfectly. Infinitely adjustable. About as light as you can possibly get, short of adding lightening holes in the lever.
Re: sonex trim systems
Posted: Tue Mar 03, 2015 9:47 am
by DCASonex
Seems many of the proposed alternatives to the Dial-a-Trim just regain the functionality of the original simple lever. I have mine set straight up when neutral. On landing, flip it back to full nose up after putting in 10 degrees or so of flap and leave it there until on the ground. No need to be ultra precise on setting for takeoff, the forces are not that great even if you forget to reset it. (Been there, done that). Can trim to hands off very easily with slight movement of the lever, not over sensitive. I have auto-pilot that gives visual indication of need to adjust trim on scale of 1 to 10 up or down. Very easy to adjust trim with that lever to keep neutral, Dial-a-Trim or the like would work as well for that, but doubt if it would be a real improvement.
In my setup, have center stick with dual side mounted throttles. Electric flap switch right next to throttle, and the trim lever just below the throttle. One hand remains on stick, the other on throttle. That would not be possible with dial-a-trim or the like, and electric trim would add no benefit over that lever. Have flown a Sonex that had dial-a-trim, Owner tended to leave it set in one position, and missed out on advantage of being able to quickly adjust it when landing.
There are plenty of things that one can improve on Sonex. For example: My electric flaps and hydraulic brakes means all controls are in reach and I can keep shoulder belts tight at all times. That trim lever may look crude, but it works, give it a try.
David A.
Re: sonex trim systems
Posted: Tue Mar 03, 2015 12:42 pm
by ihab
radfordc wrote:When you lowered the flaps there was an immediate strong nose down force. It was nice to be able to trim off most of the pressure with just a quick tug on the lever.
Ah thanks (and same for the subsequent replies by others).
One of the cool things about the mighty Flycatcher, actually, is that if you are trimmed for your pattern speed (90 kias or thereabouts), extending flaps does not require any trim, so you just drop flaps, point at the runway, and land.
Ihab
Re: sonex trim systems
Posted: Tue Mar 03, 2015 10:35 pm
by paulonex
Can you provide a few photos of the lever trim system w/trim tab - to see if I can reverse engineer it for the onex
The onex uses the spring system and I’m not a big fan
Thanks
Paul
Re: sonex trim systems
Posted: Tue Mar 03, 2015 10:53 pm
by fastj22
paulonex wrote:Can you provide a few photos of the lever trim system w/trim tab - to see if I can reverse engineer it for the onex
The onex uses the spring system and I’m not a big fan
Thanks
Paul
I’m surprised the Onex uses the spring system exclusively. I would think it would be like the Sonex and allow either. I do understand why the Waiex and Xenos must use the spring.
Re: sonex trim systems
Posted: Wed Mar 04, 2015 2:57 pm
by n502pd
Hello again! I have updated my info on my clone of the Dial-A Trim system. Please see my kitlog site at Joseph A Nelsen - Experimental Aircraft Builder's Log, and look for 3-4-15 entries. there are 4 of them. comments??