Next task (WINGS) The reinforcment of the wings should be much quicker than the stab. WOW!!!!, Was I shocked when I removed the sheeting, it appears that somewhere in this kits life a mouse, yeah thats right a MOUSE took up residence and was having a great time chewing the balsa ribs and skin, leaving behind little turds. In one of the photos you can see a round balsa patch in the top wing skin where the little critter chewed a hole and another where it chewed on the ribs.. Anyway I reinforced the gear mounts with triangle stock and epoxied the entire area with two part resin. Doing so will allow the resin to wick into areas that were not glued by the manufacturer it will make the wood structure much stronger. I guess I will find out when I do the first landing. I plan on using E-Flite retracts as it does'nt make sence to install more expensive gear in a plane that might leave the gear on the runway and the plane in the dirt. I also plan to make the inner gear doors on a door sequencer. See the photos.http://www.rcuniverse.com/forum/atta...mentid=1987383http://www.rcuniverse.com/forum/atta...mentid=1987398http://www.rcuniverse.com/forum/atta...mentid=1987384http://www.rcuniverse.com/forum/atta...mentid=1987385http://www.rcuniverse.com/forum/atta...mentid=1987386http://www.rcuniverse.com/forum/atta...mentid=1987387http://www.rcuniverse.com/forum/atta...mentid=1987388http://www.rcuniverse.com/forum/atta...mentid=1987389http://www.rcuniverse.com/forum/atta...mentid=1987394http://www.rcuniverse.com/forum/atta...mentid=1987395http://www.rcuniverse.com/forum/atta...mentid=1987396http://www.rcuniverse.com/forum/atta...mentid=1987397

If you've gone that far, take a GOOD look at how soft the wing tube ribs are. On mine those ribs were only half glued to a full length soft balsa shear web, not even the spars. Second flight one came apart.

If you have an incidence meter, I'd appreciate a reading on washout. Set mine to 2 1/2 negative, identical to the Harvard, and it was overly pitch sensitive on the next flight.

Also would love to see your inner gear door rigging. Wanted to do something on mine, but the area between the inner wells is stuffed with gear and wiring. I believe in the original setup the tank fit there. I raised mine to mid level with the carb, (that original location is far too low for good flow and mixture consistency) and fit the 2S LiFE pack below it.

I would be glad to discribe and photo share the gear door set up and construction with you. Question, I assume you are flying your RB, probably one of the very few, how many flights have you done and are there any quirks I might need to know?

Only have 3 flights on it so far and have posted earlier the details, but here it is again:

Maiden was relatively easy, except with the stock gear leg mounting it wanted to nose over at every opportunity, (we fly from grass) and it was out of trim for a bit. Made up some wedge plates and cut and epoxied the mount slots for the new orientation. Moving the wheels forward when extended reduced that tendency a lot.

Have a vid of the maiden here:

https://www.youtube.com/watch?v=CAMpvFxMCkc

Held the tail down for the crosswind and it launched earlier than expected. Was out of trim for the first minute or two. Also needed more expo on elevator. Kept the speed up for the first landing as a stall that low can ruin your whole day.

The bounce on landing was due to a rise in the runway. That has caused all sorts of grief to the Harvard I flew immediately before and that one is on its fourth retract version to try and tame the beast, (in all the flights not one landing where the gear has survived, all because of the wire geometry. Now have struts, so it should soak up the bumps without leap frogging back in the air.

Back to the Bear. On the second flight things were going much better, with trims and expos making a big difference in manners. Only problem was my camera card was full and my friend was heading back to the car to get another when it flipped to the right. Gave it left aileron and it returned to level, then immediately flipped over on its back. Cut the throttle and watched an inverted flat spin disappear into the beans beside the runway. Things looked pretty ugly and I went as far as to grab a garbage bag to pick up the pieces. Pretty surprised to find some gelcoat damage, a broken receiver battery box above the engine and a mark on the back of the pilots helmet.

The cause was immediately apparent as the wing tube had torn out the bottom of the right wing. Luckily, when it flipped over the wing snapped back into place long enough to stabilize the descent. Had nothing to do with me as I doubt could pull off that maneuver with this plane if I tried.

That's the reason I stressed having a look at the wing tube mounting. The structure and bonding on mine was so poor it was a wonder it didn't collapse taxiing across the field.

Only "Homer" during all of this is I did not measure the washout on the intact wing before carving off the lower skin. As mentioned, I made fixtures to hold 2 1/2 degrees negative while bonding on the new skins. Next flight was so hairy in pitch I landed gear up, (breaking off the muffler outlet pipes). Had confirmed CofG after the repair and again once this was over. Was bang on the money. I had made no programming changes and this is identical to the Harvard, which is pretty tame in the air, so cannot account for this behavior.

The inner gear doors are complete, (see photos). I used light ply to trace the contour of the front and back of the openings and 1/4"x1/2" balsa to join them and sheeted with 1/8th" balsa. Surface mounted mini servos with the servo horns glued to the inside of the door with a adjustable connector on the servo output arm. The doors are covered with white monokote and the trim color is model masters brass paint for air brush application. The color match is not exact but close and it's on the bottom so I hope I don't get to many complaints about the match.I installed and set up the door sequencer w/3sec. delay to be sure the gear will not interfer with them. they are mounted to the fuse with Great Planes fabric hinges and CA glued. If anyone has any suggestions or comments I would be greatful.http://www.rcuniverse.com/forum/atta...mentid=1990990http://www.rcuniverse.com/forum/atta...mentid=1990995http://www.rcuniverse.com/forum/atta...mentid=1990998http://www.rcuniverse.com/forum/atta...mentid=1990999http://www.rcuniverse.com/forum/atta...mentid=1991000http://www.rcuniverse.com/forum/atta...mentid=1990996http://www.rcuniverse.com/forum/atta...mentid=1990997http://www.rcuniverse.com/forum/atta...mentid=1990991http://www.rcuniverse.com/forum/atta...mentid=1990992http://www.rcuniverse.com/forum/atta...mentid=1990993http://www.rcuniverse.com/forum/atta...mentid=1990994

Beautiful work. I have to admit to not thinking there would be enough room for a servo in the well itself. Solves so many problems.It might take a bit more work now, but another option for me would be to mount the servos against the rear face with the shaft only protruding through the wall.

How stiff is the structure with balsa sheeting alone? Also could not spot how you hinged the doors.

Any issues programming that sequencer?

Cougar
The servos are better fit to install in the back and front well wall particularly if you do not have a servo reverser or match box. One door will open and the other will close without it. I chose to mount them in opposite positions to eliminate the match box for now. If they work I will be installing them in a perminate position thru the back wall of the well with a match box.The location for now is temporary.The balsa sheeting on the inner gear doors are strong and addaquite for there proposed purpose. They will be closed during any high speed flying and only opened during landing approaches at lower speeds. The hinges are at the very top of the well and bottom of the fuse, I used Great Planes CA hinges. The sequencer was set up using a mock up door for testing until my light bulb came on and I was successful programing them,( trial and error ) I also chose to make new gear doors to replace the supplied plastic ones. (See photos.) What size wheel did you use and mfg. name?http://www.rcuniverse.com/forum/atta...mentid=1991234http://www.rcuniverse.com/forum/atta...mentid=1991235

3" main wheels. Can't remember the manufacturer. Believe they're Sullivans.

I thought that sequencer had multiple outputs that could be set for direction. Been a while since I looked at the specs. With a P-51 and FW-190 somewhere in the schedule, will have to get a few.

Once I had the bugs out the plan was also to chuck those thin plastic gear doors. Since I redid the wells they would not fit anyway. My method to pattern this type of assembly was to tape a relatively thick and clear plastic sheet, (such as that used to cover document folders) and mark each intersection. I then transfer those intersections to what will be the door material. With straight lines joining them together this is relatively easy.

As for the door material I was going to use my standard method for making stiff structures. Two thinner sheets of ply can be layered with one or more bids of glass cloth. Flat bits are simple as the entire setup is weighted down between two sheets of 1/4" plexi. Once cured it is VERY stiff and can be cut to shape on the saw. I can tailor the number of bids and layers of ply to get any thickness and strength required. Often make wing joiners, firewalls and braces this way and can state with confidence the final product is nearly indestructible.

Contoured is a bit more difficult, using a method similar to what you had to form the inner doors. With this method you would use only the first thin sheet as the inner layer to hold the correct shape. Once removed it may be necessary to hold it in a fixture to prevent warping. I would then do the bid and sheet layering to build up the assembly.The fun is to limit the amount of epoxy while still getting a good bond by controlling the location and amount of weight used. This is where sand or shot bags are really great. Plastic sheeting is again placed over the top layer and then more thin ply to help weigh it down uniformly before the bags are placed on.

In many cases thinning with methanol just a bit helps penetrate the ply sheets. It does slow down the cure time, but that's often not important.

Once cured you can cut and sand the outline to fit.


Basically this forms a composite with wood as the laminating material. Think DeHavilland Mosquito, (without the gunfire). It can be used for simple contouring, mostly in one direction as the ply tends to only work that way. For compound curves the bid and epoxy are used alone.

The sequencer does have 3 modes of opperation, I used the simple set up mode F-1. Trying to make sense of the instructions requires a rocket scientist.

Been a while since I read the instructions, but believe those modes should select what happens to the inner doors, ie. if they remain open with gear deployed, etc. However, I would assume it would be able to select servo direction, but that may only be for gear as mechanical setups could use multiple servos linked to the separate retracts.

I have started working on the battery box and it's installation thru the fire wall into the fuse. I first built the box to enclose (2) four cell lipo's. The box will extend about 4" past the fire wall and 7" into the fuse in order to make it easy to install the batteries. I had to modify the fire wall to fit the box. The extenson of the box @ 4" past the FW is to aid in balancing the plane. I use 4000mah, and 2600mah batteries so one set is shorter than the other but the outside dimensions are the same. I will hold the battery in place with a removable cleat (one for each size battery) held in place with a dowel glued in place and a rc car body clip. The fitting into the fire wall penetration went very well and the box appears to work well. (See photos)http://www.rcuniverse.com/forum/atta...mentid=1991848http://www.rcuniverse.com/forum/atta...mentid=1991852http://www.rcuniverse.com/forum/atta...mentid=1991856http://www.rcuniverse.com/forum/atta...mentid=1991857http://www.rcuniverse.com/forum/atta...mentid=1991858http://www.rcuniverse.com/forum/atta...mentid=1991853http://www.rcuniverse.com/forum/atta...mentid=1991854http://www.rcuniverse.com/forum/atta...mentid=1991855http://www.rcuniverse.com/forum/atta...mentid=1991849http://www.rcuniverse.com/forum/atta...mentid=1991850http://www.rcuniverse.com/forum/atta...mentid=1991851

Could anyone help me with ideas on how to connect the canopy to the fuse so it can be easily removed. I was thinking counter sunk magnets in the fuse. However, someone must have a good system that does not involve ruining the exterior finish and I'd durable and easy to remove

thanks for any help

Don't know how this double post happened.

If you go back a bit I covered my mod for a quick release canopy setup. This was required since all the switches, wing retainer system and remote glow were internal to keep the model clean.

Anyway, here it is again:

Not one to like screws marring what would otherwise be a beautiful finish, thought the difficulty of accessing the systems and checking status was abysmal with the stock setup.

Therefore, I copied what my friends use for their much higher performance turbine jets by building a frame the canopy could be bonded to. This proved a bit of fun as I was working through the cockpit opening for some of it.

The first step was to make a pattern to follow for the side, front and back pieces and for that used hard paper found at the back of writing pads. The sides came first as everything would be oriented from that base formed from a single sheet of lite ply sandwich.. It took quite a few fits and removals to get the sides relatively tight to the canopy to minimize the amount of heavy bond agent required. This was true throughout the fabrication as many checks and fits were done to ensure both a tight fit and no undue stress on what was a relatively fragile skin.

The second bit of fun comes from the fact the front and back have an intersection at multiple angles and are radiused to the sides so some form of build up was required.

Once the frame starts to take shape the work actually becomes a bit easier as you can drop it on to the fuse with the canopy removed to set up the attachment points and method. To that end I drilled three holes from what was still a gaping hole at the firewall on an upward angle through the forward flange and frame. Through this would be 3 C/F rods anchored into the frame so that when it was in place there was a slight amount of force holding the frame tight to the fuse. This eliminates aerodynamic flutter and wear that could rip the canopy off in flight, yet proves remarkably strong.

NOTE: Behind both the front and rear flanges I added either a full semi circular frame, or just extra ply doublers where the pins and retainers penetrated the fuse. That skin is too thin and weak to stand up for this use long-term.

For the quick release, I fabbed the frames from small pieces of lite ply, set up so that my wire pins would slide forward against spring pressure to release the canopy. Against the wood are small washers to keep the springs from wearing in and on the pins are small wheel retainers. To be able to work them externally, I cut down those pesky thumb retainers used to hold RS232 cables to the back of your PC. They fit into the metric collars and hold the wire tight, as well and are the only pieces external.

Bonding on the cockpit and windshield are then pretty conventional. Just ensure you roughen the skin as the amount of lift generated can be surprising.

As with anything, preparation is key. The longer spent on proper fit the better it will work and look. The final proof here was the plane did a gainer into the beans inverted, with the full impact on the canopy and top of the vertical stab. Both survived and the only damage was a mark on the pilots helmet.

Thank you,

Bill........

Its great that you guys are still updating the thread......got me back to building mine ;)
Just installed a saito 125, and ordered a 90 degree nuckle for the exhast so it can be hidden in the cowl.


Last week I bought the little 620mm Rare Bear hrom hobbyking with a 4s 1000 battery........wow, is that a cool plane to fly.......blistering fast, but can also fly at a normal speed and make realy nice slow rolls.
:cool:

See what happens when you leave it alone....it had a littleun' when you weren't looking.

Would be nice if they could match the cowl color better.

You will find the 125 a perfect fit. I have a Slimline on mine so everything but the valve covers and exhaust stubs poke out the cowl.

I've been absent for a while doing other projects. I have in my absence finished the Rare Bear. Where to start, I installed a E-Flite 110, with a Castle 100amp ESC, set up on 8c, 4000mah batteries. The gear are E-flite 90-120 electric retracts with my own custom struts. 2 3/4" wheels. The prop size I choose for the maiden flight is a XOAR 17x8. The total weight of the Bear is 12lbs. The maiden flight had good ground handeling and smooth roll out, at takeoff it pitched up and to the right probably from torque. After correcting the attitude to level flight and continued climb substantial trim was required. After that excitement the Bear performed flawless and was a joy to fly. The maiden flight time was 4 minutes then set up for landing and that was spot on perfect, the roll out was a little long but the visual of the Bear on the runway after the flight was awsome. I look forward to many more great flights. I was going to do a second flight but my gear door sequencer failed and the gear would not function so I did not fly. I am using a ASSAN sequencer does anyone have any experience with it or have any suggestions to avoid future landing gear failures and possible damage?

Congratulations on your maiden flight I can't wait to get mine up in the air

Congrats on the maiden dougwilber. Any pics or vid?

Not working with that large electric rig, (except for helis) cannot say if the prop is a good match. Are you able to take current/watt readings? I'm running 16" on mine. That 17/8 may be a bit much.

You also did not say if you had sufficient airspeed at takeoff. With normal prop rotation, if too slow and on the hairy edge, the tendency is for the left wing to drop and/or a roll to the left that frequently ends inverted or close to it by the time it tries to rekit itself.

As for the Assan, no experience but would be interested to hear what you find. Have been looking at trying one of those.

My flight report and a modified photo at the El derado dry lake bed Las Vegas, Nevada. The flight take off was normal and the plane performed spetacular in the air. The landing was picture perfect, however the lake bed surface was rough and I sought out and found a rut and damaged the main landing gear. Repairs are necessary so the Bear is down for a while. Bummer!!!!http://www.rcuniverse.com/forum/atta...mentid=2025851

How fast is yours with the Power 110? I have a similar setup in mine, except I have a 16x12 three-blade on mine.

dougwilber, love that "Bob Hoover" look you have there with that hat.

Did you reinforce the stock gear blocks before installing the Eflites? Found them pretty weak on mine, (common to a lot of ARF's) and totally modded that area.

Also wanted to know if you had to cant your gear legs forward. May not be necessary as you fly off dry. With grass mine had the tendency to nose over at the slightest opportunity.

Speed??? I don't know the speed it flew at. Maybe later I can get a GPS flight. Gear mods were done with triangle stock and epoxy. Installed without any cant.

I mean ballpark. Was it quick? Sluggish? Nothing special?