• Welcome aboard HomebuiltAirplanes.com, your destination for connecting with a thriving community of more than 10,000 active members, all passionate about home-built aviation. Dive into our comprehensive repository of knowledge, exchange technical insights, arrange get-togethers, and trade aircrafts/parts with like-minded enthusiasts. Unearth a wide-ranging collection of general and kit plane aviation subjects, enriched with engaging imagery, in-depth technical manuals, and rare archives.

    For a nominal fee of $99.99/year or $12.99/month, you can immerse yourself in this dynamic community and unparalleled treasure-trove of aviation knowledge.

    Embark on your journey now!

    Click Here to Become a Premium Member and Experience Homebuilt Airplanes to the Fullest!

Question of correct incidence angle for Horiz. Stabs. on my S2L?

Find deals on ebay
Find deals on amazon
Advertise with us
This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
shocktrooper

shocktrooper

Well-Known Member
Joined
May 10, 2016
Messages
145
Location
Selma, NC USA
Greetings fellow Sonerai enthusiasts! I have been away for quite a while. My bird and my-piloting, has been in deep-hibernation for almost 3 years now!
I'm actually am a lifelong musician (drummer/vocals) and have started a pro-level rock band, based in Raleigh, NC! It has taken most of my time and all of my "flying money" to get it up and running. We are currently recording our debut LP and will release our first original 'single' hopefully by this Christmas. We have also recorded 7 rock videos to date on our Youtube channel with #8 and #9 being scripted and story boarded now. I will post a link to our website at end of this post. There you will find a direct link to our Youtube and Facebook pages, on our (Music / Video , page 3) on our website. Sorry for the shameless plug for my band here...but it DOES explain my absence from the forum and the Sonerai flying adventure(s). I have really missed it. I hope to be drilling holes in the sky again this coming spring/summer 2023.!

Just for the new-guys here...I am a retired A&P, but a 'low time pilot'. I also, did NOT build my S2L...I and the 4th owner, and purchased my bird in 'flying condition' summer 2016. I have recently started a (progressive / taking my sweet-time) Condition Inspection...and have found a few things that will need repair and or attention before I fly it again.

In summary...I removed the Horiz. stabs, elevator and the rudder for the first time...and just prior to removal of Horizontals, I leveled AC and then checked the bubble level reading front to back midway across span of stab. Both sides were a full bubble off from level. i.e., high at the leading edge. There is a 4 washer (stack) that apparently the previous owner and/or his A&P placed among the attachment hardware(AN bolt/nut) for each stab., that possibly, purposely induced this AOA into the stabs...?
On my first and and every flight thereafter...I encountered no measurable, adverse effects on take offs or landings other than...HEAVY stick forces (nose-down-pitch) to overcome (with full 10 gal. of fuel) on T.O. climb out and level cruise...after substantial fuel qty. reduction from 3/4 to 1/4 tankful...the craft seemed measurably less inclined to (dive) with hand-off stick. I know if a bird wants to do one or the other...better to pitch over than lurch up...for possible unexpected stall. All my W&B calls. have always been spot on...well-within safe envelope of published W/B parameters. My bird weighs 619.8 Lbs. empty wt.
So...since I didn't build it...have no plans or build logs...and COMPLETELY trust the 'pros' here on this forum....
Should I reset the stabs back to where they were or should I set them to dead straight and level with longitude axis. FYI...aircraft is now based at my home in my new concrete slab floor (true leveled) 30'x35' metal walled hangar. Now...finally I don't have to drive 20-30 min. oneway to a remote field or AP to lay hands on my machine.
Retirement is AWESOME and GOD is GREAT and AWESOME! AM glad to be back! Thx in advance friends and Sonerai Gurus. Rock On!
www.axialflow2019.com:cool:
 
shocktrooper said:
Greetings fellow Sonerai enthusiasts! I have been away for quite a while. My bird and my-piloting, has been in deep-hibernation for almost 3 years now!
I'm actually am a lifelong musician (drummer/vocals) and have started a pro-level rock band, based in Raleigh, NC! It has taken most of my time and all of my "flying money" to get it up and running. We are currently recording our debut LP and will release our first original 'single' hopefully by this Christmas. We have also recorded 7 rock videos to date on our Youtube channel with #8 and #9 being scripted and story boarded now. I will post a link to our website at end of this post. There you will find a direct link to our Youtube and Facebook pages, on our (Music / Video , page 3) on our website. Sorry for the shameless plug for my band here...but it DOES explain my absence from the forum and the Sonerai flying adventure(s). I have really missed it. I hope to be drilling holes in the sky again this coming spring/summer 2023.!

Just for the new-guys here...I am a retired A&P, but a 'low time pilot'. I also, did NOT build my S2L...I and the 4th owner, and purchased my bird in 'flying condition' summer 2016. I have recently started a (progressive / taking my sweet-time) Condition Inspection...and have found a few things that will need repair and or attention before I fly it again.

In summary...I removed the Horiz. stabs, elevator and the rudder for the first time...and just prior to removal of Horizontals, I leveled AC and then checked the bubble level reading front to back midway across span of stab. Both sides were a full bubble off from level. i.e., high at the leading edge. There is a 4 washer (stack) that apparently the previous owner and/or his A&P placed among the attachment hardware(AN bolt/nut) for each stab., that possibly, purposely induced this AOA into the stabs...?
On my first and and every flight thereafter...I encountered no measurable, adverse effects on take offs or landings other than...HEAVY stick forces (nose-down-pitch) to overcome (with full 10 gal. of fuel) on T.O. climb out and level cruise...after substantial fuel qty. reduction from 3/4 to 1/4 tankful...the craft seemed measurably less inclined to (dive) with hand-off stick. I know if a bird wants to do one or the other...better to pitch over than lurch up...for possible unexpected stall. All my W&B calls. have always been spot on...well-within safe envelope of published W/B parameters. My bird weighs 619.8 Lbs. empty wt.
So...since I didn't build it...have no plans or build logs...and COMPLETELY trust the 'pros' here on this forum....
Should I reset the stabs back to where they were or should I set them to dead straight and level with longitude axis. FYI...aircraft is now based at my home in my new concrete slab floor (true leveled) 30'x35' metal walled hangar. Now...finally I don't have to drive 20-30 min. oneway to a remote field or AP to lay hands on my machine.
Retirement is AWESOME and GOD is GREAT and AWESOME! AM glad to be back! Thx in advance friends and Sonerai Gurus. Rock On!
www.axialflow2019.com:cool:
Click to expand...
 
OOOPS! DOH!! I misquoted myself...hey Im old now...gimmie a break! LOL!

The H stab (lead edges) L & R are (LOW!!)...the bubble went all the way to back of the sight glass!
 
On this, every airplane is going to be different depending on loading, how it was built, wing incidence, etc.. I have mine pretty much at the bottom on the oval slot in the fuselage side. Not sure how many "washers", as I made a bushing to use instead of washers but it is definitely more than the equivelant of 4 washers. My irplane has a 2275 cc engine with full starter, and electrical ssytem, so is a bit forward in the CG range.

When I initially flew the airplane in 1992 I hadthe stab leading edge set higher and I needed to hold up elevator in all flight conditions. At that time I had no trim tab. More on that later. Ove the next several flights I continued to shim the leading edge of the horizontal stab down until it would fly without forward or aft stick pressure when in cruise flight. Full throttle I needed a very little down elevator to hold level, andat slower speeds I needed up elevator, including in the traffic pattern. I did not like the fact that it didn't have a means to trim in pitch.

After those initial flights, having the stab set for cruise, I added a spring trim system. First I started with a bungee held to the elevator pushrod with a hose clamp and a quick cleat like sailboats use attached to the floor. It worked but was difficult to use. Then I went a little more exotic. I added a 1/4 turn to lock push-pull cable attached to the bungee that was then attached to the elevator pushrod. It added spring pressure on the elevator pushrod to trim the forces at speeds slower than cruise. Worked reasonably well and was easy but I probably needed to be stiffer (bigger bungee or a spring) as it would still need up elevator when trying to trim for approach speeds.

When I did a slew of mods to the airplane, I modified the elevator to add a trim tab on the left elevator. The tab is controlled again by a 1/4 turn to lock push pull cable that runs to an arm on the trim tab. This systen works very well and can trim the airplane for no elevator stick force from about 70 mph IAS all the way up to full throttle. This is the system the airplane currently has. When in cruise the tab is streamline with the elevator.

Personally if the airplane has flown I would set the stab up as it was and adjust from there. Add washers or shims if you need up elevator to hold it level in cruise, and remove them if you need to push to hold level in cruise. Then you can decide what you want to do as far as a trim system.
 
If I recall, the plans say start at neutral (no adjustment) and adjust with washers from there. I had over .5 inch down which compensated the full fuel on TO. However, you already have a data point from your previous set up so I would suggest adjusting more or less washers from that known point.
 
n109jb said:
On this, every airplane is going to be different depending on loading, how it was built, wing incidence, etc.. I have mine pretty much at the bottom on the oval slot in the fuselage side. Not sure how many "washers", as I made a bushing to use instead of washers but it is definitely more than the equivelant of 4 washers. My irplane has a 2275 cc engine with full starter, and electrical ssytem, so is a bit forward in the CG range.

When I initially flew the airplane in 1992 I hadthe stab leading edge set higher and I needed to hold up elevator in all flight conditions. At that time I had no trim tab. More on that later. Ove the next several flights I continued to shim the leading edge of the horizontal stab down until it would fly without forward or aft stick pressure when in cruise flight. Full throttle I needed a very little down elevator to hold level, andat slower speeds I needed up elevator, including in the traffic pattern. I did not like the fact that it didn't have a means to trim in pitch.

After those initial flights, having the stab set for cruise, I added a spring trim system. First I started with a bungee held to the elevator pushrod with a hose clamp and a quick cleat like sailboats use attached to the floor. It worked but was difficult to use. Then I went a little more exotic. I added a 1/4 turn to lock push-pull cable attached to the bungee that was then attached to the elevator pushrod. It added spring pressure on the elevator pushrod to trim the forces at speeds slower than cruise. Worked reasonably well and was easy but I probably needed to be stiffer (bigger bungee or a spring) as it would still need up elevator when trying to trim for approach speeds.

When I did a slew of mods to the airplane, I modified the elevator to add a trim tab on the left elevator. The tab is controlled again by a 1/4 turn to lock push pull cable that runs to an arm on the trim tab. This systen works very well and can trim the airplane for no elevator stick force from about 70 mph IAS all the way up to full throttle. This is the system the airplane currently has. When in cruise the tab is streamline with the elevator.

Personally if the airplane has flown I would set the stab up as it was and adjust from there. Add washers or shims if you need up elevator to hold it level in cruise, and remove them if you need to push to hold level in cruise. Then you can decide what you want to do as far as a trim system.
Click to expand...
WOW! Thank you VERY much for this response! Very detailed and VERY useful! This really helps me begin to think-up a way to get a trim system working for me on my bird! Will certainly consider and use this info. On every flight...I found the lack of elevator and rudder trim capabilities a bit irritating and tiresome to fly. I has a few service connected injuries that are REALLY catching up to me now...will be 59 in a few weeks!...one of them is a damaged left ankle joint that really starts to ache when flying my Sonerai...have to keep constant pressure on the left peddle to keep the ball centered in cruise. Tore out my Parental tendons in training back in '82...no MRIs at that time...X rays did not show it...walked ran..lived with it (with no P-tendons for almost 40 years!...VA fixed it but the damage to the joint was permanently done. "Some give all...All give some". Hurts every day. OK...no pity party fishing expedition here. Just connecting the dots, as to why I want/need elevator and rudder trim in my bird...ASAP. Again...TYVM Sir!
 
mhflyit said:
If I recall, the plans say start at neutral (no adjustment) and adjust with washers from there. I had over .5 inch down which compensated the full fuel on TO. However, you already have a data point from your previous set up so I would suggest adjusting more or less washers from that known point.
Click to expand...
Thanks Matt. I can always count on you to chime in with smart responses and usable solutions. I agree...I will put it all back as it was...or maybe adjust (as needed...just a washer or 2 at a time. Being a very 'short-coupled' airplane...it probably won't take much to induce a change. I am definitely wanting a practical, safe and useful trim system for elevator and rudder. Ref. my response above, to n109jb.
TYVM Sir, as always...for your timely and intelligent response. You guys ROCK!!:cool:
 
Thx for the kind words! I'm passionate about the Sonerai - it was a big accomplishment in my life and I'm happy to be able to give something back to this group if it helps in any way.
Yes, adjust a washer or two at a time - your weight may be different from the last owner and you may fly with half a header tank...these will all factor into where you end up with the HS incidence. It'll also change your elevator authority (range) so small changes are always best. I was full aft stick on my first landing which worked out fine, however, adjusting the HS gave me 'more' elevator on subsequent flights and less aft stick pressure needed in cruise.
 
Last edited:
That is how I rigged the stab on My SIILS/Jabiru3300. Had to weld up a new mount cause the Jabiru engines are lighter. Sorry photo is inverted.
In the end my flight adviser insisted on a trim mechanism for the stab as well as elevator trim. The stab trim is electric, also from Jabiru. Inspite of a 30:1 bellcrank reduction mechanism, if I ran out of elevator trim and trimmed the stab in flight, the whole aircraft sort of jumps to the new trim position. So Now I have data to set the stab for every load condition before takeoff.
Also have Hoerner wing tiptanks. Total 6 gals. Gives me 36 gals or 136 liters, It burns 21Liters/hr at 75% for 6.5 hours. I'd never attempts a 6.5 hour leg but I might use it to fly to flyins where there is no fuel, eg Casey in Northern Quebec.
But yes, you do start at .5 inch down, fly it and go from there.
BillE

mhflyit said:
If I recall, the plans say start at neutral (no adjustment) and adjust with washers from there. I had over .5 inch down which compensated the full fuel on TO. However, you already have a data point from your previous set up so I would suggest adjusting more or less washers from that known point.
Click to expand...
 

Attachments

  • Sonerai 20200901_170447.jpg
    Sonerai 20200901_170447.jpg
    1.1 MB · Views: 53
While you are brainstorming about pitch trim…there have been a few designs that make the leading edge of the horizontal stab adjustable from the cockpit. Mine is welded in place. The most popular is a bolt-on solution.
 
From my airplane, I would say an in-flight adjustable stabilizer is not needed, especially on an already built airplane. It would be nice, but problematic to install such a system in an finished airplane. On my Sonerai IIL, getting the stab shimmed correctly after a few flights, and adding a trim tab to the elevator was all that was needed. I looked to see if I had any pictures of the setup but couldn't find any. I may go out to the airport for something else later this afternoon and can take pictures. My tab is not big and operates well. It could probably stand to be a touch bigger, but is fine as is. This only requires cutting into one side of the elevator to make the tab, and running a push-pull cable back to it. I'll see if I can get pictures today. This would be my recommendation for trim.
 
Hi Ed,

Fred had this system on his 2L. I thought there were drawings on this site...but can't find them now.

Essentially you mount a pulley and drive thread to the fuselage crossover member (using the holes normally used to fix the leading edge of the stab). The mechanism sits above and behind the crossmember and drives a jackscrew fixed to the horizontal stab leading edge (also using the existing mounting holes).

The pulley is driven from the cockpit via 1/16" tensioned cable. My welded system uses pulleys on each end as well. However, I connect the pulleys with ball chain. I drilled indentations into the driven pulley to engage the balls. The cockpit pulley is simply an idler. I move the ball chain by hand rather than by rotating the cockpit pulley.

I will root around for some photos.
 
Bil438 said:
That is how I rigged the stab on My SIILS/Jabiru3300. Had to weld up a new mount cause the Jabiru engines are lighter. Sorry photo is inverted.
In the end my flight adviser insisted on a trim mechanism for the stab as well as elevator trim. The stab trim is electric, also from Jabiru. Inspite of a 30:1 bellcrank reduction mechanism, if I ran out of elevator trim and trimmed the stab in flight, the whole aircraft sort of jumps to the new trim position. So Now I have data to set the stab for every load condition before takeoff.
Also have Hoerner wing tiptanks. Total 6 gals. Gives me 36 gals or 136 liters, It burns 21Liters/hr at 75% for 6.5 hours. I'd never attempts a 6.5 hour leg but I might use it to fly to flyins where there is no fuel, eg Casey in Northern Quebec.
But yes, you do start at .5 inch down, fly it and go from there.
BillE
Click to expand...
Thanks much Bill! I will put it back where it was...take a measurement (look for .5") and see where its at. So...the ".5 inch down" is...down from dead level with long axis..ie from a level leading edge on the stab?
 
ChuckerF14 said:
Hi Ed,

Fred had this system on his 2L. I thought there were drawings on this site...but can't find them now.

Essentially you mount a pulley and drive thread to the fuselage crossover member (using the holes normally used to fix the leading edge of the stab). The mechanism sits above and behind the crossmember and drives a jackscrew fixed to the horizontal stab leading edge (also using the existing mounting holes).

The pulley is driven from the cockpit via 1/16" tensioned cable. My welded system uses pulleys on each end as well. However, I connect the pulleys with ball chain. I drilled indentations into the driven pulley to engage the balls. The cockpit pulley is simply an idler. I move the ball chain by hand rather than by rotating the cockpit pulley.

I will root around for some photos.
Click to expand...
Some color pics would be great if ya can find and post them. At your convenience of course. Thx bro!
 
You must log in or register to reply here.

Latest posts

Back
Top