How many Robart Hinges does it take?
 

I was just wondering how many Robart hinges to use on my H9 Edge 540? I bought the 3/16" hinges and was wondering how many to use on each aileron? Should I use them on the other control surfaces as well? How many there, same size?

Thanks for the help?
Jeff

One more thing
 

What is the adhesive of choice on Robart hihges? Is seems to me that epoxy would give more time for accurate placement of multiple hinge installation.

Jeff

How many Robart Hinges does it take?
 

I have always spaced them just the same as any CA or klett type hinge.

Epoxy is just great and an easy way to use it is to coat the hinge area with some Vaseline (don't get it on the 'spike' ends that will be epoxied) then glue one side first to either the trailing edge or the control surface. After the epoxy has set it's easy to install the other side. - Watch the gaps between the surfaces and recess the hinges a bit to keep the gap to a minimum.

While you're at it check out the Robart hinges with a control horn on one half. They give a strong control attachment that doesn't have exposed screws on the top surfaces.

quint :D

How many Robart Hinges does it take?
 

Quint,
Thanks for the reply.

Is it easy to align the hinges when glued in the first half? I'm talking about the rotation (I guess) so the pivot point is parallel to the wing or aileron or ?

I saw the Robart hinge with the control horn attached. I wondered about those. I like the idea of no exposed screws. I was considering using controll horns with ball links to help minimize free play (or at least that was my thinking). Is free play a problem with the combination hinge/control horns?

Thanks :)
Jeff

How many Robart Hinges does it take?
 

It's quite easy to align them, just fold them over to have the free end pointing up or down at 90 degrees and make sure they are all lined in a straight line by placing a straight-edge such as a ruler across the hinges. The rotation is natural since they have to hinge up and down... ;) If you decide to use the units containing the control horn, be sure to cut a very narrow slit into the surface that will receive the horn and test fit them before epoxying. - When the epoxy is setting is no time to find out the hinge won't slide all the way in because you forgot to cut a slot for it. :eek:

Free play is not any more of a problem than other methods since it's mostly based on hinge and linkage slop. The Robarts have little free play and don't seem to loosen up with time.

quint :D

How many Robart Hinges does it take?
 

Thanks again Quint!

Jeff

How many Robart Hinges does it take?
 

One more thing, H9 recommends that the mating edges of the wing & aileron be sealed with monokote or ultrakote to eliminate flutter. It would seem easy to do using CA hinges, is it still possible with the much thicker Robart hinges?

Jeff

How many Robart Hinges does it take?
 

The sealing of the gaps is really effective on these big models. I sealed the gaps on my Sig SU31 and was absolutely amazed at the increase in control effectiveness. I used the gap sealing tape from Northeast Sailplane, it's great stuff. I actually had to program out a little of control throw for low rates.

Vince

How many Robart Hinges does it take?
 

Thanks Vince,
I'll see if I can find some. What is it like? And, are there any difficulties using it with Robart hinges, since you can't really get all the way to the middle?

Jeff

How many Robart Hinges does it take?
 

Vince,
Is the gap tape shown below the one you recommend?
Is the hinge tape used the same way or as a hinge?

Thanks,
Jeff


Hinge Tape and Gap Seal

Hinge Tape is made of tough transparent mylar and comes in a 10-foot strip. Once you stick this stuff on, it won't come off, so be sure to align it properly before applying pressure.

Gap Seal is a stiff mylar that has adhesive only on one half of the tape. It is designed to seal the gaps in your wing at the surface hinges, yet allow for smooth movement of the hinge. This stuff works great, and we highly recommend it. It will stick to covering or natural wood finishes.
Hinge Tape (10 feet) $4.95
Gap Seal (10 feet) $4.95

How many Robart Hinges does it take?
 

Jeff, I conclude from your posts that you may not be planing to set the Robart hinges deep enough into the surfaces. When using them, (Remembering to coat the hinge pin areas with Vaseline) push the hinge deeper into the wood so that the two surfaces have no more gap than a CA hinge. - In the case of a tapered control surface and a square cut trailing edge, it means that the leading edge point of the surface touches the trailing edge by sinking the Robart hinge into both pieces, leaving only the hinge pin exposed.

Apply a strip of sealing material with an accordion fold to allow for the movement of the surface(s). - Heck, I use a 1" wide Ultracote or Monokote strip pre-folded lengthwise and applied in the gap from the bottom so it doesn't show from the top. ;) This will give you good control authority at low speeds and along with a tight linkage and strong servos can push surface flutter out of your flight envelope.

quint :D

What about Servos?
 

Hi Quint,
I do have a tapered control surface and a square trailing edge. I will sink them deep as you describe (touching the trailing edge). Vaseline sounds like a good idea too. As far as sealing, is an UltraCote seal on the bottom enough? I don't have to seal both sides?

As far as servos, I will probably go with Hitec's since my budget is not unlimited. I will look for high torque, but should I go with metal gear or digital or ? I'm not too knowledgeable about servos. Also, does Hitec make decent receivers? My primary (Futaba) one is in my Spacewalker. Heck, i would switch the two if the Futaba is much better. I'd hate to loose my Edge to a receiver hiccup. I have a Futaba 8U radio.

What would I do without this NG, you guys are great! :)

Jeff

How many Robart Hinges does it take?
 

A strip of Ultracote applied to seal the seam along the bottom is enough, there is no need to do both sides. I like Hitec servos very much and they are a good buy for their performance. The Hitec 605BB is a good choice if limited in budget:

http://www2.towerhobbies.com/cgi-bin...1&I=LXN588&P=0

But the 645MG is very nice for metal gears and not much higher in price:

http://www2.towerhobbies.com/cgi-bin...1&I=LXUZ90&P=0

The Tower Hobbies Receiver is the same as Futaba and better priced:

http://www2.towerhobbies.com/cgi-bin...I=LXJB52**&P=7

And finaly, you might find a complete Hitec airborne pack with the servos you want at a good (package) price if you call around a bit.

quint :D

How many Robart Hinges does it take?
 

On Edge:

You just received very good info for what you are doing.
I used the stock ca hinges on mine, but had several of them break. I use Robart hinge points on everything else and have replaced the ones in my edge.
I have been using elmers poly Pro bond for the hinge points, with the way that glue expands it fills any void and has proven to be extremley strong, it does take a lot longer to set but I think it is worth it.
When you get to fly it, use the elevator throw they call for, I think it was 9/16 up & down, It may not look like enough but it is plenty, if you use any more than that it will be prone to snap.
Even with that little elevator throw, the plane will do a very tight loop.
I am using Hitec digital non coreless 5645 servos, they have been great.
Good luck, Have fun, it's a nice plane.

More servo questions...
 

Jemo,
Thanks for the info. Where do you get elmers poly Pro bond?

Can anyone tell me the pro's & con's of metal gear and digital servos? When and where are the prefered uses?

Jeff

How many Robart Hinges does it take?
 

Probond,
Any hardware store should carry it. Canopy glue will also work well for hinge points and you can clean up with water!.

Countersink the hingepoints so the control surfaces will touch when they are installed and dry fit everything.
I use vasaline applied to the hinge pin and fingers with a toothpick and heat it to get the vaseline into the joints. Wipe off any on the outside.

Glue both sides at the same time and flex the control surface to make sure everything is lined up. As you flex the control surface the hinges will line up if they were fairly lined up to start with.

The Hitec servos are the best on the market. They draw less current than many regular servos while JR and Futaba servos draw much, much, more current and are more likely to overheat.

The coreless Hitecs are the best but will cost about $75.00 dollars, still alot cheeper than JR at $118.00 or Futaba at $139.00 which have less power, less speed, and more current draw.

You will have to CALL around for that price because it is below the manufactures suggested price.

Brian
KB1DTB

How many Robart Hinges does it take?
 

Thanks Brian!

Jeff

How many Robart Hinges does it take?
 

I bought the corless 5945 from Chief aircraft for $75.00 each.
www.chiefaircraft.com

And the non corless 5645 from servo city for &50.00 each
www.servocity.com

How many Robart Hinges does it take?
 

Jemo,
What are the advantages of coreless servos? Are they worth the extra $$$?

Jeff

How many Robart Hinges does it take?
 

Jemo,
Same thing for digital servos, what are the advantages?

Thanks,
Jeff

How many Robart Hinges does it take?
 

Digital servos are supposed to be better for various reasons, holding power, centering etc.
The non corless will be fine for your edge, even a lot lesser servo will be ok.
I got the coreless for my Carden 30% extra just because I wanted the best I could afford.
You can never go wrong buying the very best servos, but you probably don't really need to spend the extra money unless you are into serious contest stuff.
The Hitec servos are programmable, using their servo programmer. From what I understand you can set and match centers, reverse etc., some people really like that function.

Don't forget , strength is the important thing if you are into 3D.

How many Robart Hinges does it take?
 

The cored or coreless Hitec's are superior to any other manufactures servos and the coreless Hitec's use less power and are stronger than the cored servos.

Brian
KB1DTB

How many Robart Hinges does it take?
 

Skypilot_one

Yes, I like them both. I first used the non coreless, 5645 in my Hanger 9 edge and liked them very much. When I built the Carden 30% I used the coreless 5945, they are great as far as I am concerned. I am running thr 5945's on 6 volts, plenty of speed and lot's of power.