So, I'm working on the wing for my Seagull Sparrowhawk 71" and thinking there is no mechanical reason that it will be any stronger with the two center ribs epoxied together than if I assemble it at the field with just the tube and two wing bolts. Anyone else have these thoughts?

I have built the plane and test flown it. I also have the bigger version and will build it this Winter. I don't know if it will work as you desire. The presence of the adhesives on the wing tube and the glue on the two plywood base ribs certainly adds strength. The absence of the adhesives will be a weaker structure, but by how much would be the question.

Try it, but go easy on the test flights. If you see wrinkled covering afterwards, stop flying, and glue together as designed. Good luck and please share your results. Bye the way, the Sparrowhawk flies real nice! Mine has a DLE 20 and it will sustain a 45 degree climb and the engine is well hidden in the cowl. There are pictures of the engine install in the thread dedicated to the DLE 20.

Thanks lifer,

I'm not trying to discount the positive way epoxy will help keep the wing from coming apart laterally, but I question how much the expoxy will help keep the wings from folding. As to keeping them together, I have some nice 1/8 spruce ply that I will make a wing bolt saddle with and some aluminum tubing to line the wing bolt holes in the wing. I will report back if this is not enough

Maidened today with a brand new Turnigy HP26S 26cc gasser.
I had set the CG at 115mm behind the most forward part of the wing per the latest Horizon Hobby update. WAY too nose heavy!!!
Luckily the lead wasn't attached well and fell off and the plane began to fly normally.
It's FAST! As befits a racer. But it floats so much it's hard to land.
The CG is at the forward lateral wing tip brace. Set there, the elevator is neutral. I am using low rates which is plenty.
No problem with the gear, even after an excursion in the weeds off the runway

edpare,

Can you provide your new balance point? Mine seemed a little nose heavy and I would be interested in trying your revised balance.

Thanks in advance!

I'm finding this difficult to describe because I don't know the terminology but here goes:
I know the pieces of balsa going fore and aft inside the wing that give the film covering shape are called "ribs" so I am going to call the pieces of balsa going side to side in the wingtips that give the wingtips shape "riblets".

Thus, the balance point is at the first forward "riblet" (You'll need a helper)
This should be the approximate location of the wing spar - most of my planes balance at or just forward of the wing spar.

Ideally, one would measure the chord (leading edge to trailing edge measurement) at a given point, in the case of the Sparrowhawk right at the fuselage, and then measure the balance point. That point would be expressed as a percentage. In most cases, the percentages fall somewhere between 25 to 35 percent of the chord.

The parts on the tip you referred to are called tip gussets.

I wouldn't trust the spar as the assumed balance point as some designers can put them pretty far back. The thickest point of the rib profile, sometimes called the high camber line, is usually a fair guess however.

Thanks Lifer,

I actually knew all that but you asked where my balance point was so I told you.
Balanced there, at the most forward wing tip gusset, the plane is "in balance", thus does not pitch up with additional power nor dive when power is reduced. I haven't the nerve for inverted flight yet as the motor has only one hour on it. The elevators are as inline as I can detect and high rates are enough for aerobatics.
FWIW: the wings are not epoxied together and nothing seems amiss.
FWIW2: Landing gear is not bending - maybe some others had too much weight in the nose?

So, did you end up doing the no expoxy mod on the wings to make the wings removable? How did it go? Any photos of your mods? Thanks, DG

Yes, we have no epoxy in the wing tube or wing root ribs. However, I taped them together anyway until I figure out a more economical way to transport them.