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Old Jul 26, 2012, 10:59 PM
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Canada, AB, Calgary
Joined Jun 2011
34 Posts
Interesting range of suggestions...

1. first thing I checked was if the wheels were spinning freely - check
2. then I checked if the tailwheel was loose or misaligned - check
3. reversing the gear gives it a rear sweep with the wheels under the CG for easy nose overs. The forward sweep must be normal and not the result of a crash.
4. checking for symmetry showed a difference of 1/8" in the left and right forward sweep (photo) - corrected now. I can see that being a problem perhaps.
5. both wheels were splayed out (as in not pigeon-toed) - better now. Really hard to bend the short axle bits.

Will test it at the field this weekend. Thanks for the help.

I replaced the BL25 motor shaft and the motor isn't running as quietly as it used to - sounds a little rough when it starts up - and in the meantime the Hyperion ZS3025-8 970KV I ordered has arrived. I was hoping to fly it on the BL25 for a set, then swap to the Hyperion and feel the difference the same day or next. Should I bother risking a deadstick on the repaired motor? I imagine the beating it took getting the shaft out couldn't have been good for it (installing the new shaft was a breeze). I've only had the plane out five times with about 6 flights each so the stock 'feel' isn't ingrained in me yet.

Also attached some pics of an aileron horn that just pulled out before any crash.. epoxied it back in, pulled the other out, and epoxied it too.

HS-82MG's are waiting to be installed next.
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Old Jul 27, 2012, 12:39 AM
certified crash instructor
Scottsdale Arizona
Joined Dec 2009
2,214 Posts
The same thing happened to my aileron horns, the replacement wings have a tab now with 2 screws going thru to horn. I would use the hyperion motor, try to check amp pull though, mine pulls over 70amps with a 12x6 vox prop, haven't tried the stock prop. I'd hate to see you brownout, you may want a bigger esc to open that motor up, otherwise you probably won't notice that much difference, has more torque, better for harriers and hard climbs. I noticed it's not as easy to stall now which help on slower landings.
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Old Jul 27, 2012, 07:42 AM
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Canada, AB, Calgary
Joined Jun 2011
34 Posts
Would appreciate a photo of your aileron horn setup if you can, slo-fly. I hadn't thought about doing bolts/screws through foam like the balsa planes are done. I know that glued/epoxied horns are a no-no on 60-90 size balsa warbirds, and with the size of the control surfaces on the Yak, can imagine this must be an even greater concern.

I have a CC ICE Lite 75A that would suit the amp draw you're seeing, and it looks like it would be a good slide in fit in the Yak. I'm running a well-balanced 12x6 APC TE with a 13x7 waiting to be tested. I'll run the watt meter on it and post the numbers, but I find that the CC datalogging shows lower amps and power output, even in the same static tests which is confusing.

I'll run the repaired BL25 initially and keep the plane over land (there's a lake/pond next to our field) just in case. No point in repairing a motor and not testing the result!
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Old Jul 27, 2012, 03:43 PM
certified crash instructor
Scottsdale Arizona
Joined Dec 2009
2,214 Posts
I'll try and get you a pic tonight, work has me tied up. I think I was around 1100 watts with a 13x5, 1200 watts and 78 amps with a 12x7 and now I'm using a 12x6 for 1100 watts. I could probably push it more but I'm in the middle of Arizona summer. Curious to see what your 13" prop pulls, you may need 100 amp esc!
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Old Jul 27, 2012, 04:03 PM
smoke is my wattmeter
Longview, Tx
Joined May 2008
1,124 Posts
It really sounds like the bearings in your repaired BL25 are hammered. They're easy to damage in an accident and when pressing the motor apart/together. I get bearings from rcbearings.com. Great service and prices.
My new wings have the new horns on them and I didn't bother with the screws. I epoxy the horns in the ailerons. I really can't see them getting pulled out. The rubbery, silicone looking glue that Eflite uses is a different story.
I killed my 4s motor on my last crash. I've got a good 3s motor I may try when I rebuild. It's good for about 650 watts with a 13x6.5. It's just hard on batteries.
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Old Jul 28, 2012, 03:55 PM
More Speed Indeed!
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USA, AZ, Tucson
Joined Nov 2007
1,020 Posts
Looking for a "New" canopy, anyone have one they would like to sell? Horizon Hobby shows them on back order, and not due until mid august
Thanks,
Mike
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Old Jul 28, 2012, 06:53 PM
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Canada, AB, Calgary
Joined Jun 2011
34 Posts
Here are some photos of the new motor and ESC with datalogging results at 3500' altitude, 73F. Not the wattage expected but the ESC datalogging always give figures quite a bit less than the watt meter. The ESC cut off twice in flight running the 12x8E prop returning to power a few seconds later, so I'm guessing the 30C 4S 2.8Ah Zippy's don't have enough juice for the high pitch. Max current draw was 70A so it wasn't the ESC cutting out. Don't have a 13x7 on hand to test yet.
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Old Jul 28, 2012, 07:29 PM
certified crash instructor
Scottsdale Arizona
Joined Dec 2009
2,214 Posts
I forgot to mention I run hyperion 35c 2950mah 4s, and 12x6 vox wood prop, probably why are numbers are so different. I haven't tried the stock lipo, the 2 I had caught fire when it crashed. Hyperions are pricey but I get 40 percent off if I bring in a crashed hyperion lipo to my lhs. That and the 6c charging rate makes field charging much quicker. I haven't tried anything bigger than a 13x5 or 12x7 yet, haven't tried the stock prop or apc props yet. On my first flight with new motor I chunked a 13" prop, I think the extra weight and springy gear isn't helping my situation either. I think I'm gonna ditch the telemetry, get a smaller rx, and probably a hobbywing esc to lighten the load a tad.
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Old Jul 28, 2012, 10:50 PM
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Canada, AB, Calgary
Joined Jun 2011
34 Posts
A lighter ESC and better wiring would solve most of the weight problem but I'm just glad to have it up in the air with unlimited vertical at a tad past half throttle. With the extra weight I did notice it comes in for landings faster and needs more runway for roll-out. I'll stick with 12x6's for now. Would be nice to have better batteries but cycling through three packs charging at 2C (the advised limit on these Zippys) in 20 minutes keeps me going pretty much non-stop.

I'm thinking of putting some fiberglass and resin on the rudder trailing edge to harden it - it's getting a bit mushy with hanger rash.
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Old Jul 29, 2012, 11:43 PM
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Canada, AB, Calgary
Joined Jun 2011
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On the 8th or 9th flight this morning, while banking to make the approach to land the ESC cut the battery off and rather than fly into a barbed wire fence, I ditched it in the pasture. It was a combination of getting a little too happy with the WOT high speed passes (it's my first plane after the Nexstar trainer, I'm allowed to enjoy some speed finally!) and a poor choice setting the Castle ESC to hard low voltage cutoff (the default) rather than soft cutoff, which would have given me the time to make a decent landing. You don't want the ESC to cut power completely when making a low cornering approach to land!

True to the many posts in this thread, the Yak broke cleanly just behind the canopy, the canopy popped off, the pilot bailed out (and in my disgust I forgot to look for him), and one of the elevator hinges popped up through the foam. On later inspection the stock rudder servo was doing the jitter thing with no input. Motor and ESC appear to run ok at the moment.

A gorgeous Sunday flying day aborted, I spent a few hours with some epoxy and CA, canopy glue and a couple HS-82MGs to replace the rudder and elevator servos. I need another long servo arm before I can do the ailerons. I figure since everything that people say can go wrong has gone wrong, I better swap out the servos before worse damage occurs. Post #424 and #2695 were excellent resources on replacing the servos.

The end result is fine. Appearance-wise, the worst thing that happened was caused by the repair job -- I won't be putting masking tape on the paint again.

Is there a good marker or something that will match the blue? I tried a blue Sharpie but the color is too light.

Jittery servo vid - link.
Why you want to match the rudder and elevator with the same servo - link.
HS-82MGs on both rudder and elevator link.
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Old Jul 30, 2012, 06:16 AM
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Joined Sep 2010
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Just had to ask, for first plane past a trainer, were you flying with that much movement on elevator and rudder? If so, I commend your abilities - you are learning very well and doing super.
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Old Jul 30, 2012, 08:10 PM
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Canada, AB, Calgary
Joined Jun 2011
34 Posts
Haha no.. I use very low rates with at least 30% expo, experimenting with high rates only when I'm very high up and my finger not leaving the switch (had a few panic attacks). I've built three .60 size warbird kits now and I'm trying to catch up on the flying skills before I risk them - figured a large foamy would be a less painful next step.
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Old Jul 31, 2012, 02:22 PM
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United States, MS, Biloxi
Joined Feb 2012
454 Posts
I switched to high rates once, and ended up in a cow pasture too No damage on that flight, but flew out of range on last flight and mine looked similar to yours. Since then, I have a new motor from ebay, $20 and seems to run cooler, that Im gonna try out hopefully this weekend. BTW, this has been my first plane so you can understand why those high rates seem really intimidating to me. This plane wasnt meant for a beginner!
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Old Jul 31, 2012, 03:05 PM
certified crash instructor
Scottsdale Arizona
Joined Dec 2009
2,214 Posts
The yak still makes me nervous and I've been flying for about 8 years now. I fly my 3d depron biplanes much more, I can get crazy with those and still be relaxed, much less nerve wrecking. I have one bipe for front yard 3d thrills and the other bipe has 200 led lights for night flying, sometimes the fun never stops. I prefer the bipes cause it's like flying in slow motion, I seem to learn much quicker with something super slow and floaty, keeps me out of trouble!
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Old Jul 31, 2012, 04:19 PM
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Joined Sep 2011
668 Posts
If anyone's interested, I have a brand new E Flite 60amp ESC (same as stock) that I don't need. PM me and we can work a deal. I pulled it from the new Parkzone Habu 2. Never flown, only bench tested to verify it works, which it does.
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