|Nov 06, 2012, 10:00 PM|
Y'ever get the feeling that on some of these planes, they're just stuffing in some motors they found in the back corner of a warehouse, or from another model that just didn't sell?
Example - the ArtTech 2-meter Minimoa. The motor in that thing is designed for something like 8.6V (or as ridiculous) & at that, wouldn't get out of its own way. I can easily imagine the full list price for it would be under a dollar. I mean, before being 'assigned' to the new plane.
Not that it necessarily applies here.....just sayin'.
|Nov 07, 2012, 05:47 AM|
Perhaps a paragraph I posted elsewhere recently would show you the direction my heart leans:
"You know who I really envy with the sailplanes? Those guys who fly from crests & ridges with deep valley around them. I live in what's called the 'coastal plains'. It just seems cool as all heck to be able to dive & fly below where your feet are planted then bring 'er up & keep going -- & being able to see the top of your plane while it's flying! If we had that kinda terrain anywhere nearby here, I'd live there!!
Seriously, I'd really luv to try that some day. "
Had a thought. Check out the background terrain in this vidi I shot early on as our last Spring fly-in was getting cranked up & you'll see what I'm talkin' about.
Pancake City!! *LOL*
|Nov 10, 2012, 06:42 PM|
Absolutely Glorious day Down East here in NC today -- I had some errands to run 1st thing this morning, came out of Lowes about 10:30 & couldn't help thinking there oughta be a law against having to work on such a beautiful day! I knew right then I wasn't gonna wait 'til the club meet Sunday to go flying, so rushed home, packed up the Corvalis & went out for the re-maiden.
She flew beautifully - only needed a couple clicks of down trim to straight-&-level at half throttle. This on the new (replacement) 'loaded fuselage' Tower sent, including motor & ESC. Bu-u-u-ut....there's a glitch. Motor's cutting out intermittently. Only a second or two at a time, but enough to be worrisome. Landed 'er, got a buddy to hold the tail while I ran it up to full throttle & held it for 20-30 seconds at a stretch; half throttling between....didn't miss a beat while on the ground. Same LiPo, took off again....still sputtering just as before.
Landed again, changed to an 1800mAh 30-50c NanoTech, to make sure I didn't have a cold solder joint on the stock battery (I change everything over to XT60 conns) -- still cutting out.
Going back out tomorrow, gonna take a spare 30A ESC and change over, see if that might be the problem. Also planning to take the one out of the 'bad' original along, but I'm a li'l worried that might be defective & what caused the 1st motor to burn out, so if the replacement ESC smooths 'er out, I'll prolly just try the old one on the ground, keeping close watch on it & the motor's temperature.
I did get one piece of additional data before launching today that I'll share -- on the optical tach on the ground at max throttle with the supplied 15C LiPo & stock prop (Grayson hasn't yet delivered my freakin' 3-blade spinner), I'm reading 11,100rpm.
I'll post how things go after tomorrow's session. It's supposed to be another beautiful day with a couple knots more breeze & 2-3 degrees warmer so, already looking forward to it. Gotta get the LiPos on the charger so, 'til then!
[Edit to add]:
Oh yeah, almost forgot. Those 2 notches just in front of the landing gear struts? They are for removing the wing(s) without removing the gear -- and they do work, without cutting. Remove the 2 screws, pull up on the rear of the wings until the struts sort've lodge against the ends of the flaps, gently 'force' the wings towards the rear until the 2 pins on the front dislodge from the sockets enough to 'drag' across the foam between the sockets & the bottom. Taa daaaaa!
|Nov 12, 2012, 02:31 AM|
|Nov 12, 2012, 06:17 AM|
Thanx Andy - yeah, I know. If there's one thing I've learned building these planes with mfr-supplied components that you can solidly rely on, it's that they'll provide the absolute minimum things they can get away with. This is really telling when you see videos from the distributors where they themselves upgrade the ESC or something before filming.
Thing is, I didn't have a 35 or 40 to upgrade to, and even if I did I would've wanted to test using stock components. When I measure performance, I want to get data using what is supplied so we'll know how effective - or not - what we're buying, is.
That said, the intermittent motor bug is alive & well. In a kind've brainfart I didn't think of the other 30A ESC I took, not having a connection wire long enough to reach the Rx, so I ran the ESC from the 1st 'bad' plane (only) and it's still 'cutting out' for 1/2-second or so about once or twice a minute. Flew 2 sessions yesterday - I crammed the full-house EagleTree logging system in & will download & read the data a little later this morning. I was disappointed the ESC changeover didn't solve the problem so 1st flight was rather short, but I ran another 1800 LiPo out on the 2d flight in hopes longer run time would give better analytical tools.
One thing of note - I took infrared (non-contact) temp readings directly off the LiPo, ESC and motor after both flights. Surprisingly, the motor was the coolest of the three!
Even so, at this point I'm about 90% convinced it's a bad motor. Haven't told this but, I'm half convinced the replacement 'loaded fuselage' Hobbico sent me was one they'd had returned; very possibly because of this motor problem. The foam was considerably more 'dinged up' than the 1st one, plus the decals are messed up (missing small pieces) here & there. If I find out they did, trust me I'm gonna be plenty pissed!
For the other 10%, there's only 1 element I can think of. That's the AnyLink system that I got with my Tx-R version. What's raised the eyebrow is, the motor seems to do that 'skip' in roughly the same 2 positions up- & down-pattern from my pilot's station; ie at about the same angle left & right of me. That's a little freaky. It's got me wondering about the radiation pattern of the antenna on the AnyLink, or perhaps in-plane antenna interference.
My immediate plan before giving up completely on this motor is to eliminate the AnyLink as the culprit. I'll bypass the AnyLink by installing an A6100 Rx & binding directly to my X9303 Tx. Until I've completed that test, I just can't put my full faith into this AnyLink system. I'm already wishing I'd gone the other way - but for a couple different reasons I won't go into here.
I'll close by asking has anyone else got the AnyLink & perchance noted any kind of the hinky activity I'm experiencing?
|Nov 12, 2012, 12:54 PM|
A cautionary surprise!
I'll share with y'all a lesson I learned this morning, thanks to the EagleTree data I logged yesterday. The Corvalis' cooling system seems to be pretty efficient. While it's in the air!
Below is an ET chart from my 2nd session on an 1800mAh 25~50c NanoTech, showing RPM, Altitude & Watts, with 3 active Temperature sensors, for your study.
TempA (Lilac) is LiPo
TempB (Orange) is ESC
TempC (Red) is Motor
ESC was warmed up from my doing a prelim check on an external 2500mAh LiPo pack before closing the cowl to fly - that's why it starts off a little higher than ambient ~80°F. You can easily observe what the temperatures do while in flight. But check what happens after I land, while taxiing back into the pits! I should point out that the temperature rise 'lags' a few seconds behind the actual power bursts. And this was on grass. But this little detail with the temperatures surprised the crap outta me!
As you can see, I flew for 6.5 minutes, at abut 10,300 rpm (between 60-75% throttle after leveling off) - didn't really dog it. You can see where I got up to about 200' checking flaps & stall character a couple of times. This session ran the LiPo down to 11.15V (not plotted on this chart) and I just took it off the charger; it took just under 1200mAh to top it off.
But think about it. You take 'er up, fly around awhile, & land. LiPo's somewhat depleted at that point, and then you start taxiing on that already weakened battery, with lessened cooling effect. All I can say is, if you do taxi after landing, don't do it for long!!
I didn't plot Pack Voltage or Amps on this chart - the plots pretty much overlay the Watts (product) line & only the scale out to the left changes. If anyone wants to see those specifically, I'll replot & post it up - just let me know.
|Nov 13, 2012, 02:55 AM|
Good point, StarHopper44. I was taxiing my Parkzone Trojan all the way back to the pits on Sunday, after each flight (I fitted bigger wheels). I've never given any thought to how hot things get doing that.
I guess if the ESC is only just big enough to cope, the heat is likely to build up more. Bigger ESCs will have lower impedance FETs, so the same current won't make them as hot. Your taxiing temperature curve for the ESC looks quite alarming.
|Nov 13, 2012, 08:46 AM|
Andy, next time do it & quickly pop your cowl & put a finger on the power components.
Then get a good landing practically at your feet (ie, no taxi) and give 'em a feel. Would luv to get confirmation from another stock setup Corvie re this phenomenom.
Also, forgot to mention it but in the chart (full-size view) you can also see the watt (brown line) spikes where the motor is 'skipping' as I'd mentioned. Really scratching the ol' noggin on this'n!
I'm in a quandry about what to do about it. Tower has already replaced it one time & I'm hesitant about bugging them again not knowing the exact cause, y'know? I'd like to really nail down what it is before approaching them again, but the Wx forecast shows the cold rainy season is upon us (this past weekend was phenomenal!) & with traveling for Thanksgiving weekend is looking like it might be up to 3 weekends before I'll get to fly again.
Anybody like to gird up my courage with what you would do in this situation?
|Nov 15, 2012, 12:13 PM|
All I can suggest is, if it happened with two different motors, list what parts you used in common in both cases - one of those is probably the cause. Was it the same ESC? I've lost track. Same receiver, at least?
|Nov 15, 2012, 01:38 PM|
Horizontal Stab & Elevator
Prop nut & washer.
Hmmmmm. It was that damn prop nut, wasn't it?
No, and yes.
First flight with replacement motor/ESC/Rx, motor 'skipped'. Changed ESC to former unit (the one from 1st fuse assy which motor fried 6mins into maiden); motor still skipped.
Rx in replacement fuse assy is only 'unchanged' component, tho I seriously doubt it's the problem. Nonetheless, I intend to change it (an AnyLink Rx) over to a Spek A6100E, bind it straight to the X9303 Tx (ie, no AnyLink module) and try again. If motor still skips, it HAS to be the motor, no ifs ands buts or ors!
There's an added element to all this I haven't told, as it's perhaps at the root of everything but unproven. Just, something that has had my suspicions up from the start. I notified Hobbico Support about it earlier today, and awaiting their response....not wanting a lot of time to elapse until I get another test session & then have them thinking 'he broke it' or such, since we have ugly Wx moving in here, Thanksgiving weekend traveling, yada yada & I might be 'grounded' next 2-3 weeks. I'll reveal that other element if & when the situation calls for it; right now I'm not looking to embarass them since thus far they've been very cooperative in trying to resolve the issue(s).
|Nov 17, 2012, 06:49 PM|
Nice bit o' flyin' there Yarsy....hope you can find some time to work on those landings tho.
*ROTFL* Just kiddin' of course -- nice work!
I wish our field had at least a small paved section. It's amazing how much grass that front wheel picks up, even when dry. Static I think contributes.
I noticed that yours too wants to veer left on takeoff roll - prop torque no doubt. This is my first plane with trike gear, & I'm unsure how to counter that, realizing that opposite rudder would tend to make it want to 'shoulder over' in the already pushed-down direction. At least, mine does that in the grass, with its naturally longer roll. All I've done so far is keep the throttle pegged & elevator stick back, hoping it'd lift off before it reaches the soybean field.
So far so good, at least!
Anyone, any suggestions?
BTW - no flying today. Wind was howling, & rain with that wind's coming in tonight so no Sunday either. Upcoming weekend I'll be on the road, to home town for Turkey Day so no flying then either. So right now looking like maybe 3 weekends hence - Wx permitting - afore my Corvie tastes the sky again.
|Nov 18, 2012, 02:20 PM|
Joined Nov 2006
Nice video, Yarsmy! I like your new motor set up and will consider doing that should the need arise. Right now, I have a lot of hours on my Corvalis with the stock set up and I just can't seem to kill the thing. Still on only my second prop, too.
Hi "Hop. I feel your pain. i have had numerous seventy-five degree or more days with only gentle breezes, and failed to fly. Yesterday and today I got up, ready to go and had to contend with downpours. Sigh. Days like this I take out the Easystar with the big motor and the soda bottle underside. Slides across wet grass and puddles like a seaplane!
As far as your turning on take-off tendency goes, you might try what I do. Flaps down, full up elevator and apply the power in a smooth and steady motion. Even on wet and moderately thick Bermuda, the nose comes up quickly and there is always enough rudder to counteract the torque. Once the nose is up, I reduce the up elevator and she just floats off. I usually never get to full power, unless the grass is really wet. I tend to avoid touch and goes in those conditions because the nose wheel is usually locked towards the end of the take off roll due to grass being jammed in the pant. This means slow, high Alpha landings to keep the stress off the strut when the wheel is locked up. I just noticed some excessive slop in my nose gear caused by a crack in the plastic where the strut enters the pant. New one due at the end of the month from Tower. I might try bigger wheels all around. A closer fit might keep enough of the clippings from getting up inside and jamming the wheel.
Some mods are in order. Mine always seems to want to roll to the left. easy to trim out, but it results in a very sluggish roll rate to the right. I have checked for warps, misalignment, and a dragging flap, and all have checked out OK. I might get a new wing and see if that changes anything. that would also aid me in collecting enough spares to support the plane when they discontinue it, as will happen eventually. It is a neat plane and worth keep around for a long time. Two years of flying has only produced some minor hangar rash, so barring any stupid moves, she should be around for a long time. and, with enough spares, I can always build another should the unthinkable occur. Also looking to move the battery back a bit, maybe mounting the cowl with a catch and magnets to open from the rear, and some paint and details. Of course, I will be adding the Dynam three blade prop. Another thought is to slave a gyro to the ailerons to improve windy weather operations. I picked up a used Flyzone Skylane set up this way and it is amazing how steady it flies, even in gusty conditions. The Corvalis probably won't do as well considering the bigger wing, but who knows? It is worth investigating.
Hope you can find some time and weather to exercise the bird the bird before three weeks goes by. Keep us posted!
|Nov 18, 2012, 04:15 PM|
Wilco, Reid. I'll give that takeoff with flaps technique a try.
You gave me another idea also - a bigger wheel for the nose. That would both raise the prop & nose pant up a bit out of the grass - the whole front end for that matter - giving a little better angle for taking off. Can't help but think that latter would provide for shorter t/o run, too - mine are longer than I would've anticipated - she doesn't really 'jump up', & looks very scale. When I advance throtle to t/o, (& it's smooth progression, not 'drag racing') my Corvie really looks like it's trying to stick its landing lights into the dirt. Wish I had a video to show. (Forgot camera last week ) Anyway, will be near a couple LHS's while traveling this coming weekend, & will check the next couple of up-sizes to try, keeping it scale-'like', & see if it helps. Will keep y'all posted.
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