I am using the gauge on the meter per the instructions and it is likely I am getting it backwards so I apologize for any confusion. What I know is that I have downward incidence (.5 degrees) without shimming the main wing compared to the rear stab. Unfortunately I glued the stabilizer into place when I first put the plane together assuming that the kit was good to go out of the box. It was only after I read this and other threads that I found there may be issues so I rather than building a new rear stab I would first like to make sure that remediation is needed.

My first issue is determining the datum line. If I use the horizontal line or molded seam about an inch or so under the main wing my rear stab has about +2.5 of incidence and the main wing is about +2. If I raise the rear to get level or 0 on the rear stab then the fuse is pointing downward but this is not out of line with what I have observed on my super cub when I do the same test. It is with this alignment that the main wing goes to -.5 degrees. Then when I shim to get +2 the leading edge is about 5/8 - 3/4 inch above where it would be if bolted directly to the wing bed.

I read in one of your previous posts that originally you had the same incidence between the main wing and rear stab or 0 difference and now you are adjusting to +.8 difference where the main has greater incidence. Maybe I should tone it down a bit to match those settings? I'd be curious to know how it worked for you. As I stated before my known high wing flyers have 2 degree difference but those are a single engine configuration so that may be appropriate for them but not a twin.

Hello freddy, I am not an expert on these matters but I can relate my experience. I believe the most important angle is the wing and plus 2-3 degrees should get you in the air without a problem. If the horz stab is close to the wing then you should be well within the elevator trim range. Again you should be in the air without a problem. If after you get it in the air and trimmed and find that you have 8-10 degrees of up elevator then you may want to shim the wing to increase the angle of incidence. That was my experience. From your measurements I would think you are ready to maiden and see what the trim is.

The real hazard is the inconsistency of the dimension between what should be identical models. You could find that you have a negative incidence and some equally off horz stab angle then get air born only find that you have a handful. Keep us posted on your maiden results.

Jim

Thanks. I reduced the shims so that both the main and h-stab have the same incidence angle. Will bring extra shims when I head out to maiden... hopefully soon.

So did it ever fly

I haven't flown it yet. I need to get a couple of large 3s batteries for ballast and some cap packs for the ESCs since the battery cables are pretty long. Money has been routed to other projects that are more aligned with my current flying skills.

One of the concerns I had is that the rear h-stab seemed to be pointed upwards too much. Now that I have some experience flying other planes and tweaking those to work I decided to pull down the transall and look at it again.

Stab definitely pointed up compared to fuselage so taking the risk that I might have to build a new stabilizer I gently removed it from the fuse with a chisel blade. Re-measured with the incidence meter and wound up dropping the leading edge 11mm so it would line up with the fuse correctly. I then built a shim from balsa and re-glued everything back together. Now I have -1.8 degrees of incidence (hope I have that right) when compared to the main wing (main wing is resting again on the wing bed without any shimming)

Re-evaluated CG and now I need much less weight up front. Glad I did that because this plane may not have survived the maiden with my lack of skills. Still remains to be seen how it flies but I did notice while checking other things the motor mounts were loose. Apparently the glue holding both firewalls didn't hold.

Still need to get batteries and cap packs for the ESCs but now I can get away with smaller 3200 mah or even 2700 mah 3s batteries rather than the pair of 4000mahs I originally balanced with and had to be as far forward as possible to get the 75mm cg point.

Today was finally the day to maiden the c-160 and happy to say the plane is still flyable

Super nose-heavy at 65mm, Pushed 2700mah 3s (x2) batteries back as far as they would go and still have a bit of up-trim. Will get that sorted eventually. Going to go back to the recommended 75mm before I put her up again. I know that changing the incidence of the h-stab to line up with the fuse is what brought the CG more in line with the manual.

Impressed with how fast this thing will fly at 1/2 throttle. No shortage of power at all using the e-flite power 25 1200KV motors . Cruise speed is right around 15% throttle. I've set 25% expo on ailerons as they are very effective. She'll float real nice too and the sound of a twin is way cool.

Full circle: although this is not the first plane I've flown it is the first twin and is the airplane kit that got me interested in flying planks. I knew from the start I was going to have to get some experience before flying her and it has been hard at times to not take her to the field. I've learned a lot about how to make this plane fly thanks to jimschroed then taking my time checking and measuring things like incidence. I'm still far from being a skilled pilot but this was a milestone for me so a grin from ear-to-ear is acceptable yes? Also thanks to my flying buddy vrated for helping me trim out the plane and taking the photos.

Congrats! Looks real nice in the air, and nice pics.

Twins are cool...

Originally Posted by cwrr5

Congrats! Looks real nice in the air, and nice pics.

Twins are cool...

\

Thank you. Yes, very cool. I did counter rotating props and don't know how much that helps but she tracks straight on the ground and in the air. No rudder or aileron trim needed.

Oh, I forgot to post a picture of the mod to the rear h-stab so here it is:

Just finished the construction of a Amain Hobbies Model C-160....44 " ws.

It is a feather with 3 heavy A123 1100 mahr cells in it. 16.5 ounces RTF. W A is 1.5 s f..

The plane is a old GWS foamy long out of production. This foam is EXCELLENT !! More like EPO. Sand off all the molding nipples. Cameo paint& full decals.

Engines are the old Hyperion 12 mm inrunners KV of 6,000 rpm turning a 4 to 1 gear box. On 9 volts the motors & gears HOWL like turbines. At about 40, thousand rpms into the gears.

You still have to maiden? Be interesting to hear your thoughts on how it flies.

I built the old GWS 4 engine version with 4 of the same motor & gearboxes. 3' roll at WOT . lift off. WAY TOO strong in a vertical climb. Great plane flown by a antsy pilot in too much wind. I will take it to my old club field for a real pilot to maiden and fly. At 82 it is time to not pilot anymore. I am a real danger to others when flying.

Looks like the 3 A123 cells at 4.7 ounces will need to be 1/2 way out of the battery space . cut out some of the foam battery compartment wall.

how far back from the L E is a more stabile COG point ?

Thank you

I am too old to remember the GWS COG point.

I did a 72 inch C-160 some years back, two 25 motors and on one 4 cell pack. The plane was crazy powerful. I still have it after many flights, never did any modes to anything other than make it electric. I use 10X6 props without counter rotating props. I will shoot some pics of her today and maybe check the weight. But I doubt I was over 6 pounds. I got it from Nitro planes years ago for 129.00 Most likely it is a CMP.
Dave
Now I want to fly her, been sitting for a year or so. been using the battery pack in other planes so it is still good.

Ok wow update. I just checked the weight. I am at 7pounds 3/4 pounds. Just never felt that heavy. Got her dusted off and gonna charge up batt. I am using a 4 cell 5000mah battery. But i think i may put a new 5 cell 5000mah 75c battery in. Maybe i can squeeze a little more time from her. Aa it was i only ever got 4 good mins and that was bout 3/4 throttle. With a lot of on the deck full throttle low passes. Just looks so cool doing that. Plus the sound is amazing. Also i put landing lights in the main wheel houses. They come on via a servo a 9 volt battery and a micro switch. So here are some pics. If i can get my brother come along i will try and shoot some low passes on the deck