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| Fixed Wing Discuss fixed wing aircraft. |
Topic Review (Newest First)
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| 03-31-2016 11:20 AM | |
| Cougar429 |
Re: T/T Rare Bear Build Log I posted one of the maiden on Pg 3: https://www.youtube.com/watch?v=CAMp...ature=youtu.be Unfortunately that camera could not zoom while active, so things are a bit far away. Don't think I have any others. |
| 03-31-2016 10:27 AM | |
| dean2287 |
Re: T/T Rare Bear Build Log That's great, flying season is here! This thread is a good read. I'd love to see a flight video of this bird. |
| 03-31-2016 07:20 AM | |
| Cougar429 |
Re: T/T Rare Bear Build Log Pretty much ready for the new season. I am taking one of the bracket screws with me to Toledo tomorrow to hopefully find some extras. Once done I will double check for any changes in the CofG. Most of my time has been working on the Seawind. |
| 03-30-2016 11:50 PM | |
| dean2287 |
Re: T/T Rare Bear Build Log Any more progress on the Bear? I like this model, hope it's in the air again soon. Looks like a real labor of love. |
| 02-17-2016 04:26 PM | |
| Cougar429 |
Re: T/T Rare Bear Build Log Nothing I could come up with would allow a second mix to tie to the flap channel directly so no way to run the LH unit independently. Bummer. I did the reverse trick again on one of another pair of servos and these move identically. May need a bit more rigging, but should do the trick for now. I omitted the servo slow feature for now until I am sure no major problems, (want them back up again quickly if that's the case). Just organizing the wiring and figure out where to run the second antenna so perpendicular and away from any other leads. If I can find more screws for the hinges on the second wing at Toledo should be ready for the season. |
| 02-17-2016 12:02 PM | |
| Cougar429 |
Re: T/T Rare Bear Build Log I've been at the fuse, cutting the side frames and dropping the Rx and distribution setup to allow more room. That meant moving the throttle servo forward which meant off came the cowl, etc. Got that finished and slid the wings into place to work on the programming. Those SOB 5245 servos died. First one and when I went to look at the other it did, as well. I had sent 3 back to Hitec for their service/upgrade and this was their first mounting. Not too impressed and a bit concerned as I fit the third as elevator on the Bobcat since it's so small and would fit into the stab. Anyway, back to the drawing board and spent most of yesterday shoehorning in a pair of standard size analog servos. Opened one up and reversed it so I could work from a common channel output. Unfortunately, since analog one has different travel than the other when means regardless of rigging they will never match through the range. Back into the spares and will see if I can get some to match. Either that or it will be setting up a Y harness to power the Rx as the only spare Rx output is used for a batt status indicator. Should have some pics up soon. |
| 02-17-2016 10:58 AM | |
| SmokeMaster |
Re: T/T Rare Bear Build Log Beautiful workmanship!! Well done!! |
| 02-12-2016 08:26 AM | |
| Cougar429 |
Re: T/T Rare Bear Build Log Now that I went looking to add some more details I was surprised I did not post about the end of last season. My friend put on his turbine event, (Thunderthrust over Chatham) and I finally had the chance to fly from pavement. Much different and if not rushed to land for full size ops would have been perfect. Worst was a bent L/G pin from a bit of a hard landing. That had it put away for the season with other projects taking priority. However, stalling out on ideas on how to mount the power and remote glow on the Texan so it did not stick out like a ........... Anyway, put that aside and got down to fixing a few things on the Bear. First was to pull off both elevators to cut them down to size. They are far out of scale and full deflection of 1/4" either way a ridiculous amount for a plane this size and expected speed. Believe me, that alone created some very interesting early flights! While working on that I replaced the stock flexible control linkage, (which would allow you to push each elevator beyond that 1/4") with some much stiffer hardware. The end result has the elevator panels approx 75-80% of stock and much closer to scale. At that time I looked into a retractable tailwheel, (it hangs out in flight like a whale giving birth) but with the time and space available took the lazy route and painted the wheel and gear white to match the fuse. Other problem is with that short cowl moment any weight back there requires 3-4X up front to balance and this plane seems to gain mass just looking at it from across the room  .Moving forward I pulled out the receiver deck to look into modding the frames to allow more room at the wing retainers. Pain in the behind now, especially if anything dropped. Still working on ideas there. Again, put that aside and went over to finally tackle the flaps. Looked at several different types and what I had to work with here in the way of hardware and structure and decided on a modified Fowler rig. All my past machines have sported split or some form of conventional. With the rather limited surface area figured augmenting the lift would help. The first was trying out different geometry to get the movements I wanted and simply dropping in Robart pin hinges was the first setup. Unfortunately the size I had were a bit too small. Forming hinge plates off the wing ribs also would not work as the trailing edge and ribs are not perpendicular. Oh well. My friend came to the rescue with some H/K hatch hinges and we did some horse trading. Not the strongest setup, but with their stock plastic pin drilled out and replaced with small brass hardware figured it may actually work with enough of them. Next was activation. All my current flap setups have them deployed with the servo arm and linkage as close to in line as possible to lessen or remove all positional stress on the servo output. What that means is the servo is not continuously fighting to keep the output in position. Less strain on the servo and power system that way. So, the standard servo to surface linkage would not work here and with removable wing panels no common internal setup hidden in the fuse is possible. The only solution was to have an internal linkage with approx the same distance between pivot and hinge as you would see in a standard control horn. Mind you, the geometry can work for you again with that only coming into play as the flaps deploy. So with the design figured out it was time to start cutting back the covering, (Yikes!) hacking away at the wing and start work. The trailing edge was roughly measured to have the top of the wing skin extend further back. With the lower skin cut along the line equal to the aileron I then glued a large balsa angle to give me the 45 degree trailing edge. The top skin was then sanded to conform to that angle. I doubled up the inner rib as it was now unsupported and filled all the little holes with spackle. I cut some ribs to match the trailing edge and started on the flaps. Had to do even more cutting of large balsa to give me anchor points for the hinges and actuator. Once everything sanded to match dropped on the other skin and worked my behind off sanding the leading edge to the correct angle and total length. All this had to match the servo and hatch installation, with the angle set up my foam packing the servo in place and then bonding the hatch in place to the blocks. The first took quite a while to ensure it all fit together, with the second done in a fraction of the time. In fact, just kept going and that second wing panel was completed in one go. As you can see in the pic sequence, as the flaps deploy the trailing edge heads aft and down while a gap opens at the front to allow airflow over the flap leading edge. Hopefully flight testing will tell if this works as intended and the best full extension. Once done the servo rigging will be set to get that straight angle at full. I'm on the final stages of covering that last wing and should have everything back in the wing bag in the next day or two. Then it's back to staring at the inside of the fuse. |
| 09-18-2015 06:52 AM | |
| Cougar429 |
Re: T/T Rare Bear Build Log I know it's been quite a while since the last entry. With some other priorities and a huge landscaping job we did ourselves, the only time I had the chance to fly the weather was absolutely atrocious. Typical. Much better this year. Yippee!  Think I burned more fuel this season than the last 3 combined.Anyway, dragged the Bear from storage and checked out the systems before putting it together at the field. Time to put up or shut up! That first flight mirrored the last, with it pitch sensitive in the extreme. Was able to make it down on the gear, but it flipped over and came to an immediate stop. No damage other than my pride. Toned down the elevator and tried again. A bit easier in the air. This time I hit a clump of cut grass on landing and broke one gear leg off. The other bent the pin. I fabbed a pair of new pins and checked through the gear. Amazingly the wing and mount structure looked good. I went against my own history with Futaba and grabbed up a JR 10X a while back, mostly due to the programmable servo speeds. That Tx has to have the most obnoxious set of instructions I've ever seen. Never could get the flaps set up on the Harvard, even with help from my friend that flies turbine with this system. In a fit of despair traded it for a 9303 and found that one easier to use. I have at least 8 flights on it this season and down to the last of the programming for the elevator. With 1/4" travel limits in flight, (pretty well the least of any of my larger craft) I run out when landing. Even on High Rate I am tweaking the expo to allow for some extra once the wheels touch. So far, we work from grass and unless cut like a Marine, as soon as that happens over it goes, (think I can count the number of taxis back to the pits on two or three fingers). This is instantaneous and does not even allow for up elevator in time. The extremely long legs don't help either. I have angled them forward as much as I dare and any extra drag on ground ops risks it at least doing a goat. The idea is to see if the largest wheels I can fit within the wells would help on this surface. Only thing I could find are a pair of 3 1/4 scale Robarts and I have to do some mods to get them to handle that weight. If things work out I may be able to try it on pavement at my friends jet event tomorrow. Only fear is grass stops it before it goes far. Asphalt would act like a grinding wheel if things get ugly. Plan to keep the original tires for the first attempt. I have some observations on this one. This winter I definitely plan to work on the internal framework to allow better access to the wing retainers. Just as often I am hunting for the rubber washers and nuts down inside the fuse and my fingers seem to have grown over the years. Although it has proven robust enough to survive some rough treatment this year, all that extra weight means landings are a bit faster than I would like. This limits where and how I can fly. Kick myself that I did not think to add flaps when the wings were apart. Perhaps it is due to the size, but does not appear that fast in the air. It seems the Saito 100 powered Super 'Bolt would blow right past it. This may be just visual, similar to what we had when the Antonov used to work out of our field. That one almost looked static on landing, everything happening in slow motion. If it could tolerate any more weight south of the border, this really needs a retractable tail wheel . In flight it looks like a whale giving birth .
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| 11-17-2012 04:14 PM | |
| Cougar429 |
Re: T/T Rare Bear Build Log I finally got the chance to fly the Bear again today and thought I would be coming home with a bag of bits again. Holy THEEIT! If the pilot had a barf bag it would have been full to overflowing. Once airborne it was immediately apparent the elevator was far, far too twitchy. It took microscopic movements to try and stabilize the plane long enough just to trim it out. That and the shakes kept things interesting, to say the least. After gaining some height I worked on feeling out the controls through the different speed range before getting up enough guts to bring it back down again. Took 3 approaches before I felt comfortable enough to touch down and to avoid ripping the gear out I landed with them retracted. Other than a wad of grass ripped up by the exhaust pipes the ONLY evidence was the fact the muffler pivoted aft to the firewall. Will have to unbolt it to retighten the adapter, but that is minor. I checked the CofG before and, due to the fact the elevator reacted as if tail heavy, again after the flight and it was bang on the rear of the wheel opening. Still, along with some Tx reprogramming I reattached the small bit of lead originally mounted to compensate for the lack of cowl for the first few flights. I found the RH retract hung up when I retracted them before coming in for a skid and finally figured out why once I had it on the stand. When I fabbed the new mount pads the Eflites were fit very tight to the slot. With me adding a spacer to the aft mount to tilt the gear slightly forward, tightening everything down placed side stress on the gear mech making them bind. As soon as I loosened the mount bolts the gear worked a charm. An easy fix with a bit of trimming to the opening. I think I can be confident in the wing repair as there was no tendency for tip stalls with very little trim required once airborne. Good thing with the rest of it. |
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