Rather than add .5oz of lead near the cg, why not go for .1oz and attach it to the tail wheel bracket or similar area at the tail.
This will give less added weight but acheive a far better 'testing' result.
Keeps it light but alters the CG dramatically (relevant to the amount added at the tail)

Just a thought

4.6oz battery? [X(]

What are you using? 2000mah nicad? [X(]

For a 40 size plane like this, you need a 1000mah metal hydride battery...... at the MOST. 4.6v or 6v .. your choice. Those battery packs will tip the scales at a whopping 2oz or 2.5oz.

4.6oz battery in a 40 size plane? [X(] You planning to fly it all week on a single charge? [X(]

The added weight is only temporary. Once the plane is balanced well other more permanent options will be used to eliminate "nonproductive" weight. If I stick to one prop (mfg & model) then no temporary weight will be necessary. However, if I play with different props to see how they perform AND I want to keep the same CG I will need to be able to add temporary weight during the evaluation period.

The battery is a 1700 mAh NiMH unit. The battery by its lonesome weighs 4.0 oz. With foam, zip tie around the foam & some adhesive-backed velcro the "final" weight is 4.6 oz. Since NiMH lose about 10% if their capacity over night I will "oversize" the battery a bit. Also, advertised capacity is 1700 while actual capacity is somewhere around 1400+ (determined by using my Accu-Cycle Elite discharge feature). In reality, when I show up at the field my 1700 battery may better be called a 1250.

A test flight this morning with 1/16" of down thrust added resulted in "absolutely no change" in the number of clicks of up elevator to have it fly straight-n-level - 11 clicks on the old trusty DX7.

Em, maybe I should just accept this airplane's "quirks" - or maybe not ...

ps - RC - your initials CH?

Cool.
Thanks

Just to verify the battery specifics (ServoCity/Hobbico.com).

Sanyo 4.8V 1650mah NiMH Battery - 4.0 oz. (4 AA size)
4.8V 1400mah NiMH Battery - 3.6 oz. (4 AA size)
4.8V 750mah NiMH Battery - 1.9 oz. ( 4 AAA size - had a couple of these for a combat plane)
not many capacity alternatives between 750 and 1400.

Pulled out the trusty straight edges & cam degree wheel using my typical "less than really accurate measuring methods" ...

Assumptions:
. SIG frequently designs their kits (source is SIG mfg rep) with the stab at 0 degrees incidence.
. I'm calling the line extending from the bottom of the stab forward to the firewall, parallel to and flush with the bottom of the stab the "datum line".

Measurements:
. The firewall is installed at 90 degrees to the datum line.
. The motor mount (mounted at 90 degrees) is angled 3 degrees down from the datum line (with washers installed). I'm assuming that this is 3 degrees of down thrust.
. The chord of the wing (center of the wing's trailing edge to center of its leading edge) is about 1/2 degree below the datum line.

In flight I'm assuming that the forces on the wing's center-line will dominate when trying to fly straight-n-level. With the stab's center-line angled above the wing's center-line the stab and elevator (when extended in the same plane as the stab) will generate an upward force behind the center of lift of the wing forcing the nose down. As a result up elevator needs to be applied to push the stab back down.

If this is scenario is correct what are my alternatives?
. adjust the elevator to be in line with the wing center line. This would requiring "breaking" the entire tail assembly apart and reconstructing / recovering.
. adjust the wing to be in line with the elevator (datum line). This would require moving the dowel hole thru the fuse down dropping the rear of the wing a bit to bring it parallel to the datum line.
. add more down thrust to the engine. The affect of this modification would seem to be dependent on throttle position.

What 'cha think?

Update: just checked the planes from a new SSE kit off the shelf: the wing center line & the stab / elevator should both be at 0 degrees. Guess that that means dropping the trailing edge of the wing a bit ...

You are correct on my initials.

Given what you've just said, I think you have positive incidence in the horizontal stabilizer.

The stabilizer is going to determine if the plane flies tail high or tail low or tail neutral. In my experience, the tail always finds it's way level when flying. It doesn't care where the wing is. The stab wants to track level. With positive incidence in the stab, the tail will fly too high and force the nose down. Up elevator trim is being used to correct and make it fly straight. I had this same problem on a Seagull Decathlon.

You can't really adjust the stab incidence now. Not without tearing it apart as you already know.

But the engine and wings are both adjustable.

You need an incidence meter. I'd prop the tail up until your stab shows 0 degrees. Then I'd put another incidence meter on the wing. I'll bet money the wing reads negative incidence at the leading edge. Thats because the stab is off to the positive side. Al you gotta do is drop the trailing edge of the wing until it reads 0 degrees on the incidence meter. This can be done with one incidence meter, but it's a helluva lot easier with 2.

The wing is on a tube. You should have an alignment dowel at the trailing edge of the wing. All you need to do is enlarge the holes in the fuse and cut some 1" donuts from lite-ply. Drill a tight hole in the center for the dowel. With the holes in the fuse enlarged, you can easily move the trailing edge of the wing up and down. Get your incidence set at 0 and glue the donuts to the inside of the fuse while the alignment dowels from the wing are sticking through. Done.

Once the wing and stab are both set to 0 degrees, I'd fly it with the CG at the middle of the recommended range. You'll need to see how it flies with the stab and wing at 0. Then adjust your engine accordingly. If it climbs when you chop throttle, you need upthrust. If it dives and drops the nose when you chop throttle, you need down thrust.

I got 2 incidence meters if you need to borrow one. Let me know. You got my email. [sm=thumbs_up.gif] You ought to come over to Pete W. house and see what we've got cookin' in his shop. We're both armpit deep in multiple projects. Tons of balsa dust and CA fumes to snort. Maybe even a beer. [8D] Careful though, Pete will hand you a sanding block and a fuse if you let your guard down.

Hey RC - thx for the info. Just spent about an hour on the horn with Pete W. Didn't know that he has built 17 SSEs.

I DO have a incidence meter and now I'm feeling pretty sheepish. I drilled out the existing holes in the fuse that locate the alignment dowel to accept a 3/8" dowel. I glued in plugs, located new centers to drop the trailing edge the necessary amount, drilled new holes for the 3/16" alignment dowel and checked the incidence angle. Both the stab/elevator and the wing/aileron pairs have the same angle. Now they have the same incidence angle.

After my chat with Pete, I am going to eliminate the engine down thrust washers. I am also going to reset the CG to 1/2" further back than the SIG recommendation. For me that will be an additional 3/8". I'm going back to the Zinger 11x6W prop for trimming flights and to help move the CG back.

I'm also going to refit the tank with small fuel line as I've been having "dead stick" issues and the fuel line I'm using is from someone else's work bench. Guess ya don't know what ya don't know until you find out from someone who does know.

Then there will be a visit to my local NAPA to pick up o-rings to refresh the OS 46 AX's carb o-ring, the needle valve o-ring and the brass fitting on the needle valve assembly o-ring.

Now if the wind will just die down a bit - today's flight was with a constant 20+ mph breeze out of the west with gusts. Made a very nice 3-point soft landing - then I packed up and left!

RC: Oh, I do have a 4Star60 wing/fuse kit that needs building. I know that it's not a 120 but maybe, if I bring the beer, I can play with you guys.

Cheers,

When I built my electric version, I stick built the tailfeathers and ailerons. I also added a full length scratch built hatch. I replaced the plywood root ribs with balsa and used lightweight covering. AUW ready to fly was 4lbs 6ozs. Flew like a feather. Although, at times, I felt it was too light to good snaps and blenders etc.

I'll try to dig up some pics later. I think I have the plans for the tailfeathers in an autocad format (I think) too.

SeamusG,
Pete and I like to build. The more the merrier, as fas as I'm concerned. Pick a spot and claim it!! If you wanna build a 4*60 then do it. I won't stop you buddy. But the 120 flies better.

You're just about ready to try a small gasser and the 120 is about the best plane in the world for a lazy sunday morning or boring holes in the sky. Take your pick. And having a nice little gasser on the nose means you can locate the tank closer to the CG and fly it for about 35 cents a flight. Glow powered, it will cost $4 per flight and it'll be nose heavy for the first 1/2 of the flight because you have to mount the 20oz tank as close the firewall as humanly possibly.

But I'm not twisting your arm or anything.

RC - as Pete keeps telling me "This is my 2nd year in the hobby - the year of many mistakes". I'm trying to get a handle on building, covering, controls, fuel systems, the electronics, engine / props, field gear - and the list goes on. Right now I'm focusing on 40 & an occasional 60 size just to simplify the various components. I have more dead stick landings than I do powered landings. Granted, very little damage but not real confidence inspiring for low level stuff !

I am beginning to appreciate both gas and electric power - cleaner, simpler, cheaper per flight. If I survive my 2nd year - who knows.

I look forward to the build party. It will give me a chance to learn so much and hopefully contribute something as well. Knowing how much space I need in my own basement to build 1 plane, how the heck are 6 guys building 120 size planes work it out?? Inquiring minds ...

I hope to get this SSE out to the field on Sunday. Need to hit Things with Wings tomorrow for some carb repair stuff 1st.

Well The word is out anyone in Arvada, Colorado area lets get together and build the 4*120's send me a PM so I can get the shop ready.

If interested.

So Seamus,
Are you just going to ignore my 'Broncos" comment several posts ago?

Well, I'm not in Colorado. Been there, and sometimes I wish I was there.
I just started my SSE. In a few months, hoping to start the 4 Star 120. Since you guys brought that plane up, I am curious if any of you guys are planning a canopy mod to the 120? I asked in another thread. http://www.rcuniverse.com/forum/m_8131900/tm.htm
If so, sure would like some info on that.
Thanks

Hey SD - emmmm, 11-10 (oops 18-10) my sympathies ...

Things that have been adjusted on the SSE ...
. new tank & fuel lines (to eliminate frequent engine shutoffs during flight)
. new needle, mixture & carb o-rings (see above - this OS 46 AX was purchased on eBay - when will I learn)
. moved the switch to pilot's left side of fuse above the tank (the tank tray was eliminated and fuel tank dropped to the floor after initial switch installation leaving room above the tank and accessible)
. expanded the old switch hole (under the servos) to be able to mount the battery snugly under the servos and added a cover

The plane now balances 3 7/8" back from the leading edge with no weight needed.

Pete W. evaluated the static (neutral) position of the ailerons and believes that a slight adjustment to both in the same direction will resolve the "11 clicks of up elevator" to achieve straight-n-level flight. I'll evaluate the current adjustments before playing with the aileron adjustment.

Tomorrow's weather is in the 60's with 4-5 mph breeze. Hope to share some good results.

My last post on the subject!

The aileron alignment adjustment was made. Subsequent flights showed no affect on the number of clicks of up elevator to fly straight-n-level.

I made the decision to "quit fiddling and fly the darn thing" - I'll just live with the 9 clicks of up elevator.

Since that decision I've had fun flying her - great fun - until today ...

I was getting a bunch of "fuel blowby" from the seams of the muffler. To clean it up a bit I used red hi-temp rtv as a head / muffler gasket, sealed the head & nut of the screw thru the center of the muffler and sealed the seam where the muffler halves joined. The results were very good. The only slop from the engine came from some fuel spitting out the carb (mounted sideways) and a very little bit out the muffler extension. Great! Less post-flight cleaning.

Well, I use 1/4-20 nylon bolts to hold the wings to the fuse rather than the SIG J-Hooks and rubber band. Worked fine until the 3rd flight today. One of the bolts vibrated loose and finally out. The result was the wing came off the plane during a roll at 100'. Postmortun - nothing that was "covered" was worth keeping.

Oh well, may my 1st SSE rest in peace(s) ...

Oh yea - SD - we got our collective butts kicked by "Oakland" [:'(][:'(][:'(][:'(][:'(][:'(][:'(][:'(][:'(]