No, I also had the short linkage (about three inches long). I had mounted the servo in the "tail brace" as it seemed like a solid point. I tend to believe what others had said here; the elevators are just prone to flutter due to their geometry. This Rare Bear gets a stronger servo, a Hitec HS-645MG. That and I will not be doing any full-throttle diving this time.

In the attached photo you can see where the servo was mounted. The brace was broken loose in the impact and thrown forward.

Here is Rare Bear #2. Just need to finish up the decals. The amount and position of the sponsors varied some while it was this color scheme, so I will probably do something slightly different from the box.

As I mentioned earlier this Bear has exactly zero exposed screws. The cowl is mounted internally with a ring, tailwheel hatch and canopy are glued on with Super Z56. The hatch is pinned in the front, tabs on the sides and a magnet in the back. It's way easier to get into as opposed to 34 tiny screws. I painted the spinner white since the Rare Bear never had a polished one.

The canopy frame was also painted with the silver being aluminum duct tape. Exhaust shields are Krylon Chrome.

Retracts are E-flite 85 degree electrics.

With two 4S 5,000 mAh packs up against the firewall it seems to balance right on the money (at the panel line). Has anyone found the recommended c.g. too far aft?

awesome car you show-off :-)

Lol, it just happened to be in the background...I swear.

WooHoo! Put two more maidens under the wings today, the second being Rare Bear. Had the inevitable stumbles. One wheel was a bit draggy and it had a tendency to nose over. Held the tail down and you can see it leap off the ground. Had elevator on high rate and consequently it was a bit pitchy for the first few seconds.

Only needed a bit of trim and was flying hands off. Have the balance as specified along the body line by the gear well and it behaved rather well. I cut the elevator and aileron control throws down after landing as it seems to need far less than expected.

Left the gear down until I'm more confident of the mixture settings. Left it a bit rich for this one. The Saitoi 125 has more than enough power, even counting the fact the prop is at the bottom end of the specs. Only wood prop I had and thought it best for the first few flights.

Anyway, it should be ready for the decals. We have a scale rally in a few weeks and it should wear all those when joining the rest of the flight line. I think it wise to only have the cowl on for display until I become more familiar with its ground handling habits.

I'm happy!

For some reason I cannot see my Youtube vid. May be blocked at my end. If not here is the link:

http://www.youtube.com/watch?v=CAMpv...1&feature=plcp

congrats on the maiden :-)

Thanks. How are you doing on yours?

Forgot to mention raising the fuel tank in line with the carb is mandatory. The engine had NO signs of fuel starvation regardless of the maneuver.

I never raised my tank...I used the stock fuel system, and it worked fine...go figure

Where are you guys liking the c.g. on the Bear? I only got to fly my first Rare Bear once (lol) but the c.g. seemed ok stock.

As I posted mine is bang on the panel line at the aft of the L/G pocket.

Some bad news to report.

As I warned earlier my not digging into the wings much deeper had worried me there were gremlins lurking in the structure. That seems to be the case here as I had it up this morning for its second flight and about 5 minutes of gentle maneuvers with the gear up it came out to bite me.

Straight and level downwind and suddenly the plane started a strong roll to the right. Tried to fight it but the plane rolled over completely and started an inverted flat spin from over 100' into the beans. Was able to cut the throttle before it disappeared. My initial thought on radio failure was discounted since I had throttle control and the most common fault to plague this plane were of horizontal tail compromises.

Grabbed a garbage bag and we headed out, strongly suspecting we would be collecting lots of glass and balsa bits. Holy THEEITT! Plane looked mostly intact as I approached and I was shocked at how little damage was done. The cause was apparent right away in the right wing as the wing tube had broken loose and tore partially out of the bottom skin. It appears the doubled and much stronger root rib kept it hanging on long enough and the inverted spin contributed to it at least remaining partially in place. There are some scars to the gelcoat, the front battery box where the weight was installed came partially loose and some dirt is impacted into the battery cover and top of the tail, but all told the major bits were carried out intact. To top it off, considering it fell on its roof from that height the canopy and cockpit were unscathed, with the only evidence some paint chipped from the pilots helmet. It will get a much closer examination, but another surprise was the firewall/fuselage juncture appear completely intact. From reports this was a weak area.

On closer examination all the wood the tube was built into was seriously compromised, with several of the sub ribs coming off the spar cleanly. This will live to fly again, but those wings will definitely have the rest of the bottom skins removed and a lot better structure installed. Luckily I will be able to use the intact left wing as a pattern for both sets of new ribs. At this point I am debating installing a shorter and smaller diameter secondary tube further aft, but have to look closer into the fuselage to see if there is room for that.

Some repair and reinforcement of the smushed fuse is in order. The receiver will be replaced just for comfort.

All told that inverted flat spin was a hidden benefit. If the wing had failed even slightly more the story would be much different.

I was hoping to have it ready for at least static display for a major scale event next Saturday. That will not be in the cards for a while now. With radio failure in the Harvard II a few weeks ago, (suspected overheating) and the Fox Eagle IV 60 mounted in the F-15 suffering a burnt piston the same weekend I'm now down to only one plane for scale events. This has been a systems failure season for me. Rather unusual. Up till now I have not lost any craft at all for quite a few years and those were to, let's say, exuberant flying.

Unfortunately my memory card filled and my friend was returning it to the car as this occurred. It would have made for some interesting viewing.

bummer...its a shame the quality control and wooden materials of these planes are so bad for such a realy nice product.
I still have not finished mine .....yet.

I just orderd the CYmodel/Easytiger giant scale Bearcat for a 90cc ZDZ engine though


Hopefully at least one bear will be in the air this year

While paint was drying in the Harvard wheel wells, (did the same gear mount mod as on the Bear) I cut most of the lower skin away on the damaged wing. The amazing thing is that it flew at all and did not fold in on itself simply taxiing for takeoff. The ribs, including ALL the structure the tube was built into are soft balsa and not glued to the aft side of the shear web, and therefore the spar, at all. It was assembled like a cabinet with only the top half of the ribs fitting through notches in the soft balsa shear web and the only glue of any substance was to the balsa skins, (also relatively soft).

All I can say to that is, Thunder Tiger, you "NOT POLITICALLY CORRECT!" *******s. This was by far worse than I could have ever expected and before anyone takes one of these airborne I would strongly advise at least skin removal to have a boo. That lousy tail construction is a good example of what to expect inside the wing. I'm surprised no lawsuits have come from this dangerous a product.

Oh, by the way, I have no way to know how their thin walled F/G wing joiner tube would have held up, but the C/F survived in perfect shape. The wing insert tube has some damage to work on, but should at least form a start on new ones if necessary.

Man yor lucky that your wing did'nt just fold up. Not alot of material there for the spar. Good that you got your fuse back though. I'd just cut the ribs out and build my own wing if that happened to me. Real shame they did'nt build this plane right at the factory I'd have one if they did.

Here is the product of a few days effort. I followed my common technique and sandwiched glass cloth between two thin layers of ply and allowed it to dry. The first two ribs from the root are 4 bids added and the outer is 8 bids added. The remainder of each sheet will be used to add doublers and gussets. along with a reinforcement to the root rib.

Ripping off the lower skin allowed me to get at the stock ribs and they were very easy to remove. I also opted to hack out the original shear web as the grain was aligned with the spars, (DOH!) and this also allowed me access to fit the new ribs directly to the spars and gear mount assembly. Removing the original tube sleeves was a bit of work to ensure they came out undamaged. Phew:rock:.

I also followed a plan that added a bit of extra work. Since the stock ribs were damaged and not to be trusted I repeatedly mounted the wing to the fuse, held it in place and slid the joiner tube in from the opposite side of the fuse. Once against the next rib in sequence I marked where the cutout had to go. Rib 2 was a bit of a mess and the doublers will cure that anyway. Once everything is in place there will be epoxy and flox added and the much tighter fitting doublers sandwiched against the ribs. Squeezing out any excess epoxy mix should ensure a good bond from the tube to the ribs.

Final fitting of the outer rib is the next step and once that is done I can start by adding balsa runners to the top and bottom of each rib to provide a greater bond area for the skins. Unfortunately I hopped over to the LHS this morning to find they were closed from this date for a weeks vacation!:yikes:.

Oh well, it's not like I don't have several other projects on the go. Hoping to put the first flight of the Harvard with the new retract installation tomorrow.

Looking good.
Glad you are rebuilding it.


Got my CYmodel/Easytiger Bearcat a few days ago.
Will go nice with a ZDZ 90cc engine on it.

Would also look nice in a Rare Bear scheme, and a chopped canopy

Wow, that's a biggun'.

Some white paint and decals would look really good there.

One thing I noticed on mine and will check on correcting was the nasty tendency to try and roll over on it's nose at the slightest opportunity. That tall gear and the recommended CofG just did not seem to work well together. I'll check on angling the gear legs forward a tad, but from the very docile flying habits on the two flights I think I can be comfortable moving that CofG slightly aft.

did you balance yours upside down at the fuselage panel line on the 2 flights ?

Yes. It was balanced at the line to the back of the fuselage wheel well.

SJN...I Love the Biggun!

see the whole F-8F thread here.....good vids there too

http://www.rcuniverse.com/forum/m_88...17/key_/tm.htm

cool..thanx!

I finally had the chance to complete the ribs. Most of the time was taken with accurately measuring for the tube fit and as you can see from the one wing installation I think I have it right. There are also aligned holes in all the ribs to feed the gear and aileron extensions or fit a guide tube if I want.

I also added enough with the doubler to prevent the joiner from busting through if pushed too hard when the wings are installed. This was a constant problem with the original soft balsa rib and doubler.

There is a lot more skin to remove and fine tuning all the ribs and edges before fabbing new skins. Still have not firmed up the decision, but the area ahead of the wheel pockets will likely remain. The conformal curves were a pain to shape and bond on and with the additional structure I do not believe there will be any compromise. I also have to decide if the current bond for the ribs to the spars will be adequate or if additional structure will need to be added. The shear webs alone may be enough.

On that note the lower spar will get C/F tape before the skin is installed. As with the Harvard I want to ensure proper washout is maintained when the skins are applied and that will require fabbing fixtures or figuring out some method to fasten each to my Adjusto-Jig.

Looks like you have turned an ARF into a kit.

Good job on the mods.

Don

Here's the latest installment. Over the course of the week I was able to do the final fit checks on the ribs and tube and bonded them in. Key was getting the angles correct with no loading on the tube to prevent easy wing joiner movement. All told I must have fit and removed the ribs and tubes at least 30 times! As it stands both wings now fit tight to the fuse, not the case with the stock installation.

The shear webs to one bay outboard of the tubes were replaced with lite ply and the BVM C/F tapes are applied. The shorter rear tape is to distribute the load from the fastener bolt and along with tying the main ribs together will bond to the lower skins. I still have to reinforce the servo pocket on the remaining wing and do some cleanup, but they are nearly ready for reskinning. On that note, in the last pic you can see the wing root fixture that sets that at 0 degrees. I removed the tips to ease the skin process and the fixture for that end to set neg 2.5 degree incidence still has to be fabbed up. They both will be interchangeable so not so much work as what I had to do with the Harvard.

As you can see I rerouted the gear lead to come out the same location as the aileron extension. Hated trying to reach them once the wings were installed and this will also simplify assembly as I won't be worried about pinching those leads in two different locations.

Reluctant to do a failure test, but can feel pretty confident they are much, MUCH stronger than stock.