i am in the process of building an a-4 and was curious as to what hinges y'all use. instructions call for nylon but was wondering if c-a hinges would work. thanx in advance---henry

Hi Henry

If you want to use CA hinges, get the ones from Sig. their as strong as you'll find. One hint though. when you install them, slot both sides with an exacto knife, slip the hinges into the one side and then into the other. Don't glue them seperately. Once it's all together, 2-3 drops per hing per side, and let it set for a while. When it's cured, flex the joint to loosen up the hinge line. Your surfaces will never come off.

Ed

BTW, whose A-4?

thanx for the reply ed. my bird is a yellow aircraft skyhawk. was hoping over the holidays to get a huge dent in the building but page 7 is missing from instr. oh well!---henry

I would recommend hinge points for a jet. Using CA may melt the foam in the wing and cause a future failure. You won't find many jet jocks using CA hinges.

MMallory,
you are correct, ca hinges will wick ca into the wing and melt the foam. CA hinges are NOT for high speed aircraft and in most situations, they can induce flutter when used on jets. It is best to use some sort of pin hinge, my preference being robarts....

luv2flyrc

How exactly would a CA hinge induce flutter? If done properly, it should be just as tight as a pin hinge. I'm not sure about CA melting the foam, but it is a good point to keep in mind. I'll check it out for myself tonight.

Ed

Hey Henry:

The Yellow A/C was the first kit for me to build as well.

I had the same question about ez-hinges, and the answer I got from the factory rep was "No, use Robart hinges".

I have yet to see a jet that has been built with ez-hinges. And since this is probably your first jet, and you will be moving on to more difficult and more high performance jets, it would be best if you got used to using the proper hinges now.

Good Luck,
Scott

Ed,

I'm not sure if CA hinges will induce flutter. However, I've seen many CA hinges tear and after a little use, some will allow the surface to be easily displaced. This may all be caused by the technique used when installing the hinge. I've also seen entire surfaces leave aircraft when using CA hinges (there usually isn't enough left to determine the exact cause. Using the Robart hinge points will eliminate one more point of concern. Starting out with jets, the more concerns you can eliminate, the easier it is to concentrate on flying.

TIP: you can use a sharpened piece of brass tubing to make the holes for your hinge points. This is usually more accurate than trying to get a straight hole with a drill bit.

Originally posted by rcav8tr [


How exactly would a CA hinge induce flutter? If done properly, it should be just as tight as a pin hinge. I'm not sure about CA melting the foam, but it is a good point to keep in mind. I'll check it out for myself tonight.

Ed

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I have to agree with Mr. Ed here. I've used CA hinges for over 10 years now without a failure on every plane. If properly done they are fantastic! Can set up control surfaces with minimal gap. I don't see how they can set up flutter if done right. If you weer to leave to much gap then I guess it would be possible but other things are contributing to the flutter.
As an aside, I once had (still do) a Byrons AT6 with a 3.7 on alchaol that fluttered the ailerons off, (not properly balanced and control horn on one end of the control surface), point is, the CA hinges ripped out great chunks of the trailing edge of the wing!!! Perhaps 1 inch by three inches long and 1/2 to 3/4" thick!!!
I would have NO PROBLEM with using CA hinges....always use Sig brand because I know they work! I have a few 10 to 15 year old planes with them so I think they will stand up to time also.

Mr. ED, I think it was you who wanted the drop tanks?

Ed,

In most cases when you use CA type hinges you will get some surface movement at the hinge line since the hinges are not stiff. I have seen a jet loose its tail due to this surface movement, on a high speed pass we heard the flutter and .5 seconds later the tail came off. Flutter split the wood at the hinge line and the surface left the plane. There was NO slop in the linkage. I too use CA hinges on my giant scale planes but on my jets.....never!

Henry, MMallory, Scott

The only CA hinges I would suggest at SIG brand and only installed as per my instructions. As Dean said, if they are properly installed, they will remove portions of the wing without failing themselves.

Scott

I'm building a Bob Parks Cyberhawk and he reccommends the CA hinges for all the surfaces. Their optional on the flap because of the range of movement required. This plane is designed for 150 mph.

Ed

One of these?: http://www.kidsource.com/cyberhawk/

Is your wing built up like the one in the costruction link, or a foam/sheeted wing?

Hi Scott

Yes, that is the one. Mine is the built up wing and will be sheeted. As far as I know there is no foam wing option.

Ed

I have to chime in here with my OWN experience with hinges. I lost my first large AD Mirage a few years ago with Robart hinge points coming loose on the elevon. My "new" Mirage has 80+ turbine flights with sig ca hinges on each elevon and its the tightest, neatest installation you can get. I also used ca hinges on my Roo and was happy with them there too. I understand ca hinges are not for every application but I would not hesitate using them again. Just follow the instructions and use a FRESH bottle of ca glue.

Vin...

Mr. SimJet Ed,

Now the fact that the split was on the hinge line and the fact that great chunks of wood were not ripped out would make me think there was not enough CA used. And if there was no slop in the hinge what did cause the flutter to start in the first place? I think too many crashes are blamed on the hinge when in fact the fault lies in the installation.

Think about it...the big gas/glow engines beat the hell out of the hinges constantly and one would think that would cause fatigue of the wood surrounding the hinge leading to a loose surface but I haven't seen evidence of that yet.

Just my thoughts....not that yours are not valid....

Mr. RAM Dean....;>))

<<<Think about it...the big gas/glow engines beat the hell out of the hinges constantly and one would think that would cause fatigue of the wood surrounding the hinge leading to a loose surface but I haven't seen evidence of that yet. >>>

Hi Dean,

I tried ca hinges after a conversation with one of the "big plane" guys at our field one day. They swear by them and abuse the heck out of the flying surfaces, thats good enough for me.

Vin...

Mr. RAM Dean

I would agree with the comment that there was an insufficient bond to the mounting area. The other thing that may have contributed to the failure was the construction of the mounting area. Craftsmanship or material. I wasn't there, didn't see it, so I won't comment further.

In the end, I would say that when mounting control surfaces, no matter what style you choose, there are somethings that need to be watched carefully.

1) Tightness of the Hinge Line - The smaller the gap the better. No gap even better.
2) Alignment - All the hinge axes need to be in line in order to keep the control surface moving smoothly and minimize any extra work on the servo.
3) Mounting - Not only do you have to ensure that the hinges are glued in properly, but that what they are being glued to is strong enough to carry the forces generated by the surface in flight.
4) Maintenance - Checking the hinges every so often to ensure that they are still bonded in place and doing their job. There's nothing more painful than losing a $5000 - $6000 airplane because of a $0.50 hinge.

Just my $0.02CDN($0.012US)
SimJet Ed


BTW, where are the tanks?

================================

I agree on all four points there Mr. Ed.

My $0.12US ($0.02CDN) $Euro..who knows.....

Ain't no tanks left....I done got 'em all !!

IMO KAVAN is the best, get them at Hobby-lobby.com at bulk prices! Cheap, reliable (sounding like a salesman aye) check em out!

I wouldn't put CA hinges on a jet, stick with the Robarts. If you do decide to go against the advise and use CA hinges make sure you put them in with odorless CA.

I have had success with CA hinges on larger planes with foam sheeted wings, but that is only because I had 1/4" thick bulsa epoxied to the hinge surfaces and I put the hinges in with odorless CA. As stated above regular CA will disolve foam (try it!), but the odorless CA will not.

Joe

the hinges i prefer for jet models are the Hay's hinges... #105.. i think... the are nylon hinges, non-pinned very much like a typical c/a hinge.. scuff them up & glue with epoxy. The work great for wings & stabs that are kinda thin on the trailing edge. Have used & seen used in everything from Top-Gun F-15's to BVM Agressors III's & Vipers... they can handle the speeds & loads... On the larger modes I like to use the the Robart hinges.... my .0002 cents worth...

Regards

Dan M.

thanx y'all for all the great help, didn't mean for it to become a debate! now all i need is page 7!---henry

Personally I prefer the flat style of pinned nylon hinges like Sig , Dubro or CG.

I fold the hinge closed & use a toothpick to put a little oil on the rounded edge. This keeps excess glue from sticking there. Then put 30 min epoxy in the slots. Also "wet" the surface of each hinge with epoxy before insterting them into the slots.

You can flex it a little to make sure of alignment, then let it harden a few hours and when you first flex the joint it will crack loose any glue that may have gotten into the joint.

Robarts are easier and very nice too, but you need a few more of them to achieve the same amount of glue contact area to the flying surface.

Have also had excellent results with the CA style, but if you have a foam core, be careful to use CA that is compatable with foam. I had some "oderless" CA one time that ate foam like crazy!

Another good trick I have learned with ca hinges is to rub candle wax or crayon at the center line of the hinge before installing them. This keeps the ca glue from hardening the hinge at the bending point. I also stick a building pin through the center when installing, to keep them centered. I haven't had one split or crack in ten years since doing this.

I lost a Regal Eagle one time because the CA hinges on the elevators failed. I believe they were the Sig ones. All of the hinges failed, they did not pull out of the wood. I then conducted a little test. If you grab both ends of a CA hinge with 2 pair of pliers and try to rip them, you can't. Now wick a little CA on both sides of the hinge and try the same thing, they will rip. I used them for years with no problems on all sorts of prop planes including pattern planes, but I would never use them again on a jet.