Finished my 4*60 kit, ran a couple of tanks of gas thru the engine. I think its ready to fly.

But.......I'm a little worried about my control surface gap. How much is too much and how would it affect the flight characteristics?

I used those du-bro nylon hinges instead of the CA hinges it came with and it looks like I've got a larger gap than my LT-40 with the CA hinges.

Also, I had to put an 8.5 oz block of lead under the engine and a 2 oz prop washer to get the thing to balance. The plane weighs 8.6 lbs dry. The book says the flying weight is 7-8 lbs so I'm a little heavy. I think I'm OK here but chime in if you get the urge.

Thanks!

Dave

Any gap at all makes a difference to the control surface response. I would try to get rid of the gap.

If you covered the model in film use a strip of film along the top surface. For example, on an aileron, push it down to full deflection, stick a strip of film down to the wing then across the gap and onto the aileron. Don't try to shrink it. When the aileron comes back up to neutral position the film should sit down into the gap sealing it off.

With the gap sealed there are a couple of advantages: the effect of the control surface is heightened, ie more powerful; and it helps stop control surface flutter at speed.

Those hinges will leave a larger gap due to their design, just seal the gap like John said.

What engine are you using? Sounds like you need to shift weight forward (battery, rx, servos) or need a bigger powerplant.

I'm using a GMS 76 and I mounted it according to the instructions (don't know better...).

I had to notch out the RH cheek for the muffler and put a hole in the LH cheek for the HS mixture control.

Otherwise, it'd be easy to shift the engine forward.

This is such a complicated hobby (I love it!) and I'll be smarter next time..........I hope.

Dave

D-LOCO;
You didn't mention the location of your battery & servos - if you can move these forward it will help your balance and weight problem.

As to the engine; If it is possible I'd move it forward too. The cowl can be recut to fit the muffler & mix control, if you are concerned about the existing holes -they can be patched.

A key factor to a good plane is to keep the weight DOWN! [:@]

Good Luck!

Hi!
8.5oz is a lot of dead weight...let's see that's around 250g...wow!!
Get rid of it as fast as you can! And move all servos and batteries /receiver as far forward as possible.
A .76 engine in a .40 trainer????
No way! Way too much engine!

Gaps are not good! Just use a strip of plastic filmcovering (Oracover) an iron it down over the gap. See picture of my aileron on my Q-500 racer.


Regards!
Jan K
Sweden

Do what johnvb said, seal the hinge line on all control surfaces. Move everything you can forward. That's a LOT of dead weight, and I'm surprised it took that much! BUILD LIGHT!

Dr.1

Jaka, it is a .60 not a .40.

D-LOCO, It shouldn't be too hard to patch the hole in the cheeks, just fill the area with some scrap balsa and a little patch of covering. Let us know if you need help with it.

Hi!
Ooops!


Jan K

Jaka- the 4*60 is NOT a trainer!

For future reference...There's no reason to have any gap just because you are using the Du-Bro hinges. Simply cut a small section from the aileron tapered front edge where each hinge is located and this gets the surfaces as close as any CyA hinge can. I cover the stationary and control surfaces with a single piece of monokote, thereby eliminating any gap. Simply cover the wing - or stab - with the monokote, then extend the control surface - aileron or elevator or rudder - away from the surface being covered and iron the monokote to the vertical part of the TE and the LE of the aileron (for example) and then cover the rest of the control surface. Then repeat for the other side.

JLNewc has the correct idea. I have done this on all my planes. This photo is control surfaces from an LT 40 I crashed last June. It is getting an "ARF bashing" All my control surfaces done this way can get close to 0 gap....... But......... then they won't move correctly most times. I flex them to the throw I want before the glue sets. The gap opens up ohhhh so slightly, and this will now be very sufficient for most all applications. .........lownslo
PS. The other photo is my LT 40 in the works.