Just got in a 4* 40 from a member here Friday.
I completed air frame Sunday. ( Kit built very easy and straight )

The question or concern is, the wing. It seems weak, it will flex very very easily, not up and down but front to back.

I was wanting some ideas on how to maybe make it stronger before I cover it.
The way it is now, I think I'd break it on a hard snap roll.

Thought about completely covering the wing with balsa sheeting.

Thoughts, ideas?

Brian

Yep.. I thought the same when I built my 4* wing... Seems pretty flimsy when built, but when you cover it, the covering gives it plenty of strength... No worries - hundreds are flying just fine as designed.. Also, wouldn't want to add weight to what is a fairly light model...

Cheers!

Jim

Thanks for the reply.
I'm a member of a small RC group in S.E Ky, and no one has one, so I was not for sure.

Brian

Once covered, the wing is quite strong.

If you have not attached the ailerons yet, may I make a modification suggestion?

Add an extra hinge 1 bay in from the wingtip. The 4* 40 has a big wing and really floats. After flying a season or two, you can make the plane a little more aerobatic by cutting a bay off each wing, shortening the wingspan by about 6 inches. The plane will roll quicker but still be a gentle lander. If you add an extra hinge during construction, it will be there to support the ailerons at the new wingtip location. If you don't clip the wings, it'll only make the attachment of the ailerons stronger.

Scott

Good one, Scott! Just about ready to hang the ailerons on mine, and will add the additional hinge... Tanks!! [sm=thumbup.gif][sm=thumbup.gif]

I have come up with a awesome idea on how to add strength to the wings and not add much weight at all.

If ya'll have built the 4* 40 then you know the wing will flex.

Now on the TE of the wing, there are two balsa sheets a inch and quarter and inch and a half in width.

This is what to do.

Take scrap balsa, the thickness of the ribs.
Go to the wing tip, and make a pattern from that.
Cut the scrap to match the pattern.
Insert the scrap between each rib on the wing, be carefull NOT to raise the balsa sheeting when you put in the braces.
Cut the scrap so it is flush with the sheeting.
Use thin CA to wick all the way down.
This has made my wing at least twice as strong as what it was before.

I'll try and upload some pic's of this modification later this evening when I get home.

Brian

I have a new 4* 40 in the box unopened, but I am planning to begin construction soon. Sig recommends a .30 to .40 glow engine; however, RCUniverse posts suggest OS .46 and similar size engines. I have a new K&B .48 -very powerful. Is this too much for this kit??

Thanks much!

Marks Towles -

(Yes, there is an "s" on Marks)

I fly (flew) mine with an OS 50SX, and don't feel that it's overpowered.

Got my ailerons reversed after a radio repair (oops!), so I am building a new one with a number of mods. I clipped the wings 1 bay, sheeted the wing, added retracts, skinning the fuse, added shaped wingtips, replaced the rudder with one based on the Venture and making a cowl. Still may make other mods, we'll see.

Scott

Do not change anything; but build it light and you will end up with a GREAT flying plane. Mine weighs 4Lbs 14.3oz and it flys great. It is powered by a Enya CX .45 and has tons of pep.

Build light
Have Fun

The Four Star 40 is very flexible as far as which engine to use.

They fly fine with a LA40 or a Saito 72. The only problem with using a 72 is the CG considerations.

Stronger in terms of flexing up and down as opposed to for and aft?
Mike

I'm not sure why people want to miss with a great design. It's Your plane do what ever You want. I have had the Four Star 40 and have now, the Four Star 60. They are such great flying planes, You have to realy work at it to miss them up.

Adding a lot of weight to this plane is the best way to make an average flyer out of it.

Light flys right.
john

You can always throttle back if you have too much engine, it is a Bear trying to throttle up an engine thats too small.

Ralph

I know a lot of people say the wings on the 4* 40's and 60"s are strong enough if built carefully, but I just don't like the flex and fragile appearance of the wings on those planes.

I just obtained a 4* 40 Kit. I plan to make a few changes. I will make another DH brace using 1/8" aircraft ply, and extend it at least one more bay into each wing. I will also add a second DH brace about 2/3 of the way back by cutting the Stock Sig DH brace thinner and gluing it into new notches. You may want to sheet the leading edge back to the first Spar top and bottom and add shear webs for 1/2 of the wingspan. The weight will go up an ounce or so, but I make up for the extra weight by using "Micafilm" which is 1/2 the weight of Monocote. I did about the same on my last 4* 60, except for the leading edge bit. My next 4* 60 will be built as above.

What I found out on my 4* 60 is that by making the inner 60% of the Strip Al. into Flaps, the plane was much easier to land as it did not float nearly as far. I plan on doing the same on my 4* 40 when I build it this winter. Just don't make the mistake I made on my 4 * 60, I increased the throw on my AL's and found out that the reduced drag of the outer 40% made it turn much quicker, so I wound up reducing the throw from the stock amount suggested in the plans, to get an easily controlable airplane. I believe the 4 * 40 will respond the same as the 4* 60 to the flaps.

Ralph

Brian,

I have seen two different 4* 60's fold the wing over the past 5 or 6 years, so I am a bit "gun-shy" of the stock wing center section. If you are careful you can reinforce the center of the wing and only add one to two ounces to the total weight. I did add another ounce by building it with flaps, but I really like the way it lands with the flaps. I would never clip the wings, in fact I always make up a 3" built up wing tip to replace the ugly squared off tip. I am probably getting enough additional Sq. In. to make up for the additional 2 to 3 oz.

Ralph

I flew a 40 for about a year. Built it totally stock and never had any problems, even when Donny the club aerobatics nut wrung it out.

It finally decided to go home to mother and flew itself into a tree trunk. Interesting thing is that it trashed the nose but the wing did just fine.

Tom

I'm thinking of building a 4 Star 40 in Bahamas to transport to UK for my son's 2nd plane, so I'm interested in any building options that allow easy transport:
- plug-in or 2-piece wing
- detachable tail section / horizontal / vertical stabilizer/control surface
- shipping box build/buy options
Any experience or suggestions appreciated.

FourStar 40 from a kit. OK, old thread, but I have to add my two cents worth.
Stock built wing and fuse, no problems whatsoever. If it can handle my violent and awkward attempts at aerobatics, it will handle anything. Snap rolls, pulling out of full-throttle dives, etc. Wing is stronger than it appears. Agree its easy to make it too heavy. I put an OS 60 4-stroker on it, had unlimited vertical but the approach looked like the space shuttle, steep and fast. Went to a Saito 50, shaved 4oz weight, same power. Flew like a dream, until last weekend. My pilot figure (Barbie doll head) took control of the plane and smashed it into some rocks.[] New kit on order, can hardly wait.

Maidened my four star 40 yesterday.

I sheeted the wing from the LE to the main spar, this added alot of additional strength and IMO improved the aethetics of the wing LE.

I have a Saito 56 in mine with an APC 12x6 prop pulls really nicely and I love the sound of the engine.

If I was to build another 4* I would do the wing mod again.

That looks real nice Andrew.

FWIW, I built mine stock and it has survived many violent snaps and hard landings. I have put the wheels into the wings a few times. I had my youngest on the buddy box and was showing him how to do snap rolls. I do them on an upline and he forgot this part and did it from full throttle at level flight, no problem.

I would ca the wing mounting dowel and hole to beef that up a bit. After MANY flights, mine got a little loose. I do this to all my planes now.

Mine has flown with Magnum 52 4st, ST51, TT46, Saito 82, OS55AX, Saito 45. Flies better lighter, still flies good with the heavier engines. The Saito 45 is off to make room for a Saito 65. The battery will need to be moved back to keep a good balance point.

Mine flew a few years at the suggested cg just fine. I started moving things around to get the cg back further. Much better!

This is a fun one!

is it ok to use a os70 4stroke in the 4*40?

Yes if that is what you have available but you will need some weight in the tail or put the batteries back there.

i have a spare 70. i could move the battery around to cg it. so its not to much motor?

You be flying around 1/2 throttle most of the time but the 70 can handle that just fine. You will like the plane

Thanks for the help