Dudley,

Since you already have the stabs mounted you might want to consider simply stripping the covering from the undersides of the stabs to access the internal structure.

As I stated a few posts back, I opened my stabs to install hard balsa blaocks for the Robart Hinge Points that I chose to use over the stock CA hinges. That is when I discovered just how thin the trailing edges of the stabs and leading edges of the elevators were. The material is most likely metric, but it appears to be about 3/16" thick which I don't believe is enough material for these types of hinges. I decided to use 3 Hinge Points per elevator, one about 1.5" from the tip of the stab and the other two on 3-3/4" centers. This put each Hinge Point between the existing ribs of the stab.

My suggestion would be to cut the elevator hinges and switch to the small Robart Hinge Points. You could use standard hinges but due the lack of material in the stab trailing edge and elevator leading edge, you'd have to add internal blocks to allow pinning the hinges. IMO, it would be easier to utilize the Robart Hinges. Once you determine where you want to locate the hinges you can just open the skins on the bottom side of the stab. I cut openings of about 3/4" width by 1" long, centered on the pilot holes drilled for the hinge points. Then cut custom balsa blocks and cemented them into position. Before I glued the blocks into the wing, I carefully dripped CA onto the intersection of each rib and the upper/lower wing skins tilting the parts as needed to allow the CA to run along the rib/skin interface. I also cut openings to allow direct access to the CF tubes to insure they are glued securely to the ribs. Once satisfied with everything, all I have left to do is close the underside of the stabs, fill the cracks, and recover the bottoms of the stabs and elevators.

HTH

Rich

Ossie

Assisted a mate with maiden of his "Rare Bear" on Monday.

Two comments.

If you're planning on putting that G2300 in yours, then reinforce everything. The "Rare Bear" airframe certainly doesn't need that kind of two stroke capacity or claimed power potential to fly either scalelike or 'reasonably' fast. I know the real one is a pylon racer. Structurally, the TT replica isn't.

The second, is definitely rework and reinforce those default U/C mounts. On the second landing which was completely normal and without excessive speed or ROD, with a marginal crosswind (torsional force) component, the right (retract) gear leg collapsed as it ripped itself and the U/C mount out of the wing. The first landing had been been smoother than the second. The default installed gear mount is not 'up to speed'. Surface was short dry grass.

Bearcat is a beautiful looking form in the air. Initial impressions are that it flies true with no particular characteristic unexpected vice. Nice whistle emanates from the cowl flow which can be heard above the engine's note.

Dudely,

If you are planning on big power I would urge you to cut unto the bottom side of the stab. Once in there you can epoxy each rib to the rod, CA each rib to the sheeting, glue tha back side of the elevator hinges. I am also going to add some light ply formers between each rib. I also would not use CA hinges.

Also, I would suggest to seal all hinge gaps with tape or untracote.

I am also really thinking about moving the elevator servo back there. There is a perfect place to mount it about 3 inches from the control arms. Then fab up a short "Y" out of 4/40 threaded wire. I have never liked the stock setup with the big long balsa pushrod. I really don't want to add tail wait, but with an OS 160 I have a little pwer to spare and will consider adding some weight to the nose to balance out. Still thinking about this one.

Also. make sure you sand the fuselodge real well where you epoxy in the bulk heads. I talked to Steve at ACE today and he said he has some reports of folks that have had there bulkheads break loose.

Update on Stab Failure

I called ACE yesterday and left a message for Steve in customer service about my stab failure. They are in the middle on inventory this week so I only got the answering machine.

Steve returned my call today and we talked in length. He was very supportive and is sending me new tail section first thing Monday after inventory ends.

We discussed the stab situation in length and we both agreed that if you plane to put the power to this plane you need to beef it up. He was very reasonable and sensible about the whole thing and had to admit that ARF's are made in factories by people that don't necessarily do it right all the time.

I personally don't have an issue with the RB or ACE. I think this is a great plane. Let me tell you, in the air she flies like she's on rails. For those of us pushing the envelope you need to expect to make mods. plain and simple. If it is to much work for you, get a different plane.

Some key points Steve made in our discussion:
* Make sure the surface where you glue you bulkheads is prepped well a good slow setting epoxy is used. He has had some reports of these break free from the fiber glass.
* The stab rods are not Carbon Fiber. They are Fiber Glass and can potentially flex. An ACE rep with the RB fitted aluminum rods inside these tubes to strengthen them. (I think this is a little much, but what do I know. I may look into getting some CF rods though, I don't want to add the that much weight to my tail.)
* Do not use more then 2 degrees of down thrust for the engine. I forgot to ask what the stock setup is but I think it is good deal more than 2 degrees.

Well, that's it for now. I strongly urge those of you running big power to cut into that stab and beef it up.

Anyone here from VAMPIRE lately? He is running a 160. How is his bird holding up?

Oh yes, one more thing. I was running an OS 160 with a Master Airscrew 16x8 3 blade. I just found a 16x10 3 blade ( didn't know they made those), so this bird is really gonna scream when I get her back up. I should have the video from the first flight up on our club site in the next day or so so stay posted for the link.

Dudley,

To add to what Jwortner has to say about installing the bulkheads in the fuselage.

In addition to sanding the inside of the fuselage (use something course and narly, like 60/80 grit) you also need to sand the edges of all the plywood where they are laser cut. Although laser cutting is pretty much the norm today it has one downside. The cutting process leaves a coating, sort of like carmelization of a Hamburger Bun on a grill, which prevents the glue from soaking into the wood, leading to an inferior joint. So sand the edges with 120 grit to remove this burned coating.

As far as adhesives go, only use CA to tack glue the formers into position. Before you glue them in, clean the area in the fuselage which is to receive the former with a solvent such as denatured alcohol or acetone after you've sanded. This dissolves the release agents and guarantees the glue bonds to the glass. Once you're satisfied with the location of the former, tack glue with thick CA and then use Zap a Dap Goo, Shoe Goo, etc. These work well to bond wood to fiberglass structures because they are solvent based, the solvent will actually slightly soften the resin used to lay up the component and makes for a very strong glue joint. If you'd rather use an epoxy product, I'd consider using 2 Hr epoxy with mill fiber mixed in until you get a nice slightly runny mixture. You don't want it too runny, because it won't stay where you apply it. On the other hand you don't want it too thick, as the mixture won't be wet enough to soak into the wood and fuselage to make a strong joint. Of course if you like to spend money you could use Aeropoxy (BVM Product) or the similar products made by 3M or Loctite. Whatever you do, don't use CA for these joints, it's just too darn brittle and will typically break loose from the fiberglass structures.

Rich

JWortner,

About the downthrust.

I measured the downthrust on my RB with the stab set to 0 degrees and obtained 3.75 degrees of downthrust. I reduced the downthrust to 2 degrees and reset the right thrust to 1.5 degrees by recutting the slots in the plywood pieces which support the firewall. I might still have the measurements I used recorded on the former sides. I'll check to see if they're still visible.

Rich

I fully agree with the statement "for those of us pushing the envelope you need to expect to make mods"; that's why I'm making a new stab. The stock stab might be OK for sport engines (with or without mods) but I'm not willing to take the chance. It will only take a few evenings to cut templates & cores, sheet, add LE/TE/tips then re-cover. Some might say it's overkill but at least I know that it will be strong enough. We've used them on warbird racers (160+) and they've never given us any trouble.

Sanding the glass before installing the formers (inside the fuse) is standard practice and I would have done it even if it's not listed in the instructions.

I suspect that at least some of the gear mounting failures might be caused by the un-sanded laser-cut plywood parts. Glue just doesn't stick to that stuff very well. Looks like some tri-stock and epoxy/milled glass will be in order.

This is STILL a great kit!

OK Bear Fans, I have the Rare Bear video online at our club website www.valkyriesrc.com. In the center of the home page is a button for this months video This was only the second time I flew it so it is nothing fancy, but you can see how a 160 pulls it along. Let me know if you like the video!!!!

Oh yes, if you go to the video page www.valkyriesrc.com/Videos.htm there are a few more videos. The one of Don Hoffman's Kangaroo jet if pretty snappy too.

All this stab talk makes me want to pull the sheeting off the bottom sides and do some glueing and reinforcing just for peace of mind!!

I couldn't agree more about what a great bit of kit this is!! I don't think I've ever bought an ARF that didn't require some kind of modification.

Nice flyin bear in that video!.. was that before or after your stab mishap?....(something's wrong with the compression though because it's very choppy even when ya save to disk)

HighSierra,

No this was the 2nd flight. I heard the noise on the 3rd flight and grought her in for a closer look.

Not sure why the video is choppy. I just viewed it with no problem.

I you like your bird I would open up the bottom of the stab and add a little more ply and glue to sure things up.

When I get the new ones from ACE next week, I am going to open the bottoms, form new skin to be ready to glue at end of operation, then reinforce and fit everthing just right, then glue the stabs on when I can glue from both inside and out, and then reskin and cover. I just opened my second stab up and it was getting ready to goo too. See next post.

Just opened up the stab that was still on the plane. This one was just started to show signs of play. The first pic gives a view of the 2nd and 3rd ribs in the stab. You can see how well I got epoxy at the end of the large rod. You can also see that while the 3rd rib had good factory glue to the skin, the 2nd did not.

The second pic shows where the front rod meets the 2nd rib (which also had good expoxy contact that can not be seen due to angle). You can see the stress cracks. You can also see where the skin is separating from the first rib, and where the factory cut through the 2nd rib.

Why don't they do a recall before somebody gets injured and they have a major lawsuit to deal with?

MANFRED....Look, If you cant find something positive to say , then dont bother posting up, Simple.

Thanks for the video!!! Great job with the website and film work. Anyone hit those powerlines yet?

BTW, video seemed to work great for me but I have broadband cable connection and powerful video card etc....

Would love to see more in the future, perhaps after your modification work is complete...

DagoNbr4,

Yes, many have hit the lines including myself. As a matter of fact, I was doing a waterfall with my 72" Cap232 about a month ago and waterfalled right into the lines!

As soon as I get the tail repaired I plan on a second video of the RB with a video overlay of a radar gun clocking it. Moving from a 16x8 to a 16.10 prop. Should be interesting.

Thanks for the thanks! It takes time to make those videos and it is nice to know when someone enjoys it.

JWortner....Great Video! Keep up the good work! The Flying Heads always get a thrill at a chance to view the flight characteristics of a plane prior to flying it. Maybe try to show us the stall speed...(at high enough altitude)
Again, super footage...What camera, and video software are you using for production?
Dudley

[>:] I was wondering if any one has used the CA hinges included in the kit ?
I have had real good luck with some of the good CA hinges never had one break or come loose. even in heavy and fast airplanes 20 to 25 lbs. and 125 plus mph.
By using these other things to make it lighter especially in the tail it will need less balancing weight.
I have a kit new in the box never touched yet. they look great, and sounds like they fly great.
I would like more info on this before I make my decision to build or sell.

Don B

...No one seems to have reported any problems with the stock CA hinges....i used them in mine ..... Provided there installed correctly you shouldnt have a problem.

For those of you that want to open your stabs and reinforce, I have attached a PDF with patterns for the ribs. I tested and at least on my printer it prints to scale. Just to be sure I included the overall length in CM so you can verify if yours prints to scale.

There are 3 ribs in the diagram, the first rib, the second rib, and a new third rib that I am going to insert between the existing 2nd and 3rd rib. I am going to extend the first rod to be longer to meet this new rib.

I wouldn't trust the location of the rod holes, but they are there for approximate reference. I would finalize them after laying them in the plane against the existing rib.

My plan is to double the first and second rib, and then add the new third rib to accept the extended front rod. I ordered carbon fiber rod from Dragonplate.com that I will use to replace the fiberglass rods that come with the kit. The rod has the same inside diameter, but a slightly larger (about .002) outside diameter, hence a thicker wall. I am a little concerned about the larger diameter because there is not much wood between the outside if the rib and the rod hole. I think I will slightly enlarge the rod holes in the ribs, and slightly reduce the diameter of the CF rod using my 1 inch belt table sander.

This may be overkill but what the heck. For those of you reading this and saying "MY GOD!!!!!",,,, I suspect that if you just cut into the bottom of the stabs and ensure that the rods are glued to the ribs, and the ribs are glued to the skin, you would probably be ok. But since I have a 160 up front, I think I will beef it up a little since I am in there.

Also, I made the new 4inch forked pushrod so that I can move the elevator servo to the rear. I know this will add tail weight, but I was never happy with that stock balsa pushrod. The pushrod is 50 grams distributed from CG to rear of plane. The servo and new linkage is about 35 grams, so it won't be to bad.

All in all I am sure I will have to add a little nose weight, but not to worried with the 160 up front.

I will post pics when done. Waiting for the stab from ACE. Hope to have it today.

Here is the template for the ribs.

Ops, just tried and can not attach a pdf. Hmmmm. I will just attach the scanned jpg. I just tried printing and if done correctly it does come out scale. If you have a problem and want the PDF send me a private message with your mail and I will send you the PDF.

Thanks for the reply Lord Lucan I will use the CA hinges then.
What do you guys think of a YS-91 for it?
We use Magnum # 2 in them and swing a 15 x 8 APC @ 9600 rpm they make goood power this way.

Thanks Don B

...check out around posts 367 [8D]...think there were some issiues wit the eng mount on the YS..and rocker cover hight..[:-]

Very cool video. I was going to go with a 4 stroke on mine but after seeing that video, I'm going with your set-up.

Now, all I have to do is save all the mods mentioned in this thread somewhere. How does one go about saving this thread to CD?

I wanted to build my RB as soon as I got it but it'll probably be a couple of years now before I get to it and I'd hate to have this thread disappear for some reason.

To bad the ARF buildewrs/dealers don't also offer the same thing as an ARC aircraft. It would save time and money at the 3rd world builders' shops and it would save time and frustration to the buyers. I'd rather be able to inspect the raw product and cover it myself...but that's just me.

Don

any recommendations on which retracts to gowith for the RB? The wire legs on the sets I've seen so far let the appearance of the plane down. Are there any suitable ones that look like the real ones too?

I am using the Robart Series 550 85 degree retract assembly that is made to accept the Robart 7/16" Series 440 Strut. I beefed up the retract mount by adding 1/4" plywood pieces underneath the current mounts. The rear piece extends back to the wing spar and the front piece extends to the back of the wing leading edge. I hope this will be enough to hold this strut setup.

I am using the 550 series Robarts as well but I am using the 663 series Robostruts. They will accept up to a 4" wheel but I may have to modify the wheel well a little bit in order to fit the 4 " Sky-lite wheels I bought for them. I bought the wheels with aluminum hubs as I really like the way they look but I may wind up using 3&3/4" tires just to save cutting up the wings. I am also installing a retractable tailwheel assy in mine but haven't figured out how to handle the gear doors for it yet. I'm kinda new to this retract thing. My only previous experience has been with mechanicals & wire struts and I always thought they looked worse then no retracts at all.