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Lowrider LSA

That was a terrible disappointment...#2 son brought a DC power station over and we hooked up the servo tester at 5.95 volts, hit the power button and all we got was 3 lights on the tester and a jerky movement of the servo shaft. Checked polarity and found it was correct. Tried again and got nothing this time but 3 lights. Turned the knob throughout it travel which apparently is supposed to provide speed control...still 3 lights and no joy from the servo.

Bad servo? Bad tester? It appears to be too simple to connect it incorrectely...red to positive and black to ground. Tried to touch the yellow wire to both power and ground...no change.

Now what?
 
Is their a polarity switch on the tester? Positive pulse servos have been out of fashion for decades, but there may be an option. You want a 1.5ms negative pulse on the yellow. And you're powering it so the black is also the ground for the signal?
 
No Sir...not that I can see. There are graphics showing which way the plug should be inserted, the knob which I believe controls speed and 3 LEDs that represent something. It seems simple enough.
 
You'll have to find a local modeller who can loan you a servo or you can try to drive one of their servos. Its tough getting started with no spares lying around. Or just buy one of the nearly free off-brand servos that are all over the web. Note on "digital" servos: they are interchangeable with regular servos, they get their info from the same analog pulse.
 
Good to know the "digital" servos will work the same way as the analog. I guess I need to spend a little more time researching.
 
Here's some pix Oli!!

Well, I tried...apparently, my computer erased the SD so I have no pictures. They really weren't much anyway...picture of the top of a wing and another shot of the fuselage jambed in the corner trying very hard to stay out of the way. I have smart phones, smart tablets and smart TV's but I remain not so.
 
Got my wing tips and the left one fits perfectly. It weights maybe 2 lbs and will be easy to fit and finish after my favorite nut plates are installed. Question is will the usual 3/4" finish washer be adequate to keep the fiberglass from being stressed and crack? The other option would be to glass in a stainless 1" x 10-32 washer on the top of each bolt hole. Other ideas?
 
What type of servo tester do you have? We had an old Astro flight at the shop it was cheap and it worked every time for any servo. Maybe post a picture of your setup and we could give our 2cents


Sent from my iPhone using SuperCub.Org
 
Lowrider said:
Question is will the usual 3/4" finish washer be adequate to keep the fiberglass from being stressed and crack?
Click to expand...
Best answer is "it depends". Ask yourself what causes the cracks in the first place? High stress loads on the fastener location? Excessive resin materiel over the glass? High or low vibration location on the airplane? High or low flight loads on the wing tip? Spacing of the fasteners? Flexibility of the wing tip around the fastener location? Is the wing tip a lifting surface or just a rounded tip?

Without knowing anything other than what you said, yes the 3/4" washer spaced about 4" +/- should be just fine. Is this one of those thin washers with a dimple? The only purpose of the fasteners is to stabilize the joint between the tip and the wing. The structural loads are minimal.
 
I have glass tips screwed to an aluminum wing with sheet metal screws, simple holes in the glass, no reinforcement. Six top and six on the bottom. The biggest stress probably occurs in the hangar.
 
After the first 1000 hours I took the fiberglass wingtips off my S-7. The earlier models, and my first one I flew for 1300 hours was one, just had the fabric covered tip bow. The later models, like the one I fly now, have a tip that it turns out is just cosmetic, but adds no aero benefit, while weighing a few lbs each.

There ARE some tips for my bird, made by a after market small shop here in Idaho, that DO add performance, Hoerner type (spelling?). I bought a pair, CF no less, and took the old (banged up pretty good from hangar rash and other things), ones off and had the new ones ready to install. This was going to involve cutting into the wing fabric as you need to get at the last full rib. I had the box cutter knife in hand and right at the last second paused: then I weighed the old and the new lighter tips. Did the math, and determined NO tips would save weight, and I wouldn't have to cut into a perfectly good fabric job, and deal with re tensioning it, I copped out. I sold the tips at a slight loss, and am waiting until I build again or have a wreck, or some reason to recover the wing, then I'd use them. The slowest landing I saw one year at JC was Joel Milloway's S-7 with his tips on it, they knock off 2 or 3 mph of the already slow speed stall.
 
Yes, thin washer with a dimple....who knew it would be this hard! I have guests from back East and kids here so it's not been a normal week. Also bought a new Tractor and the subframe that came with it won't fit my backhoe...AND trying to burn brush while things are still wet around here so as not to start a bigger fire than I planned...who knew it would be so hard!!

Beaver,

My computer hates me...I take pictures and the computer won't display them. Microsoft did some "update" and now I can't read my camera's SD.

Anyway...servo is HS-755HB and the tester is a GT Power RC Servo Tester...no model number.
 
Just watched "using the gt power servo tester" on utube, if you're getting all three lights at once the tester is bad out of the box.
 
Depending on the fit of the tip you could increase the fastener spacing to about 6" +/-. I don't think that I would do more than that though.
 
Skywalker,

I'll check out the Utube vid to see if I can figure out how this testing should occur.


I finally have a break from visitors for a few weeks and now I'm trying to get brush and stumps burned at my lot "down South" before the place turns dry and the burn ban takes effect. I'm down to the bottom of the piles which is wet and takes a long time and a lot of smoke to get this stuff to burn. I need to spend another couple days or so with the York rake getting the stick and stones out of the piles left over and one more day of burning and I'll be ready to start hauling fill into the lot to get the area where the house goes up to a level spot. Just had 40 ton of bank run dropped in the area where the hanger will go behind my shop...GREAT fun pulling big stones out of the material. We're meeting today with the engineer who is finalizing the drawings for the house...painful trying to get thru the process then on to the county to get them approved...another joyful process.

Never fear...I will get back on the plane. Just in case I sell my house in Sandpoint and need to move the plane parts I'd really like to have the left wing near finished. This moving thing is not something I'll tackle again once this one is complete.
 
Questions for those in the outback or bush or whatever...does anyone have any recommendations for solar powered threshold lights? The owners of the grass strip I'm part owner in have come up with a need for lights that we can deploy after the last snow and be put away shortly after the first heavy snow. The purpose is to define the runway threshold in "twilight" hours. These need NOT be FAA approved type lights since it's a private strip but we would like to have quality better than Chinese solar garden lights. Anything that's being used on strips without power might work since we don't want to wire them for commercial power.

Thoughts or ideas?
 
Finally got my shop doors up and functioning.
2017-06-26 16.31.54.jpg

We built a 4' x 8' platform to use with my forks to get up in the air to work on the variety of things I can't reach from the ground. Works great. Working by myself I set it where I want and climb the ladder to get up there. Progress...however slow!!
 

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You guys thought I forgot about the servos...not so, just took awhile to figure out how to post pictures again. See if this helps Beaver and Skywalker?
2017-06-29 23.44.41.jpg

Any ideas if this is the correct tester? If so, what am I doing wrong?
 

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Ha , was just thinking about this yesterday. Nice cage for the servo. Does it the controller just set neutral to the servo. It says ccpm which is a servo setup for helicopters. Can you change modes on it? I personally used an old astroflight servo tester. If all else fails get it tested at a hobby shop.


Sent from my iPhone using SuperCub.Org
 
Gosh...damned if I know but there doesn't seem to be any adjustment on the controller except for the black knob in the center which seems to only increase/decrease speed.

I ran into a fellow who flew P-38's in WWII and is now doing 1/4 scale RC and is very knowledgeable on this stuff. Problem is he's pretty much deaf and I don't sign at all. His grandson tried to interpret for me but no joy. I'll see him at a meeting on the 10th and I'll try to find out if he can help. If not, where I should go.

I really like the cage. It should take most of the stress off the bearings. Any ideas on how long this servo might last in this application?
 
E bay has them and I know these work for what you are trying to accomplish. I just searched "astroflight servo tester " as far as longevity I'm not certain.


Sent from my iPhone using SuperCub.Org
 
CCPM is not a servo signal, it's just an arrangement of common servos for swashplate control. But you should figure it out soon. If the Astro doesn't work there must be someone who's door you could knock on and borrow a servo for 10 seconds. Someone must have an aileron servo you could plug into, even if its still in the wing.

If the GT has 3 outputs, are two dead unless you are in CCPM?
 
Last edited:
Hey Skywalker!

I understand the swashplate and what it does but not the CCPM and I guess it doesn't matter since I'm not building a floppy wing flying machine anyway. From your comments I bought the wrong thing to test my servo and with yours and Beaver's guidance I think I'm on the right track now and will be able to move forward with installing the aileron servo and tab and actually test it's function. You guys have the "nuts and bolts" knowledge I lack in RC stuff and I appreciate your sharing that with me!!

One question...should the servo bellcrank only provide the movement on the control tab that will be appropriate to provide roll control at normal cruise speeds of around 130 mph? Best I can tell there is 180* movement possible from the servo shaft and I'd guess that it's probably only necessary to have less than 90* movement...will the controller accomplish this as I believe it will or will it move "lock to lock" on command? The servo seems to have plenty of power to give the tab all the movement it needs to tweak the aileron up of down.

Maybe I'm getting ahead of myself and this will become evident when I get the controller operating. Just don't want to get into the "chasing my tail" mode to get the proper of movement.
 
Well, you bought something too smart for the job. It's a servo exerciser, matcher, CCPM, toothpaste and shaving cream! Most servos will swing 90 degrees when fed a pulse from 1 to 2 ms, 1.5 center. Lots of servo testers will swing the servo, but one with digital readout of pulse width will let you set up your linkages knowing your servo is centered on 1.5ms.
 
Well....that's clear as clam chowder...which I like and had for lunch. I'm reading that as the Astro is overkill.

Maybe I need to wait until the one I ordered gets here and see what it will do for me. Making bell cranks can wait.

I'm busy now with helping build matching father and son AR-15 pistols with a 10.5" barrel in .277 Wolverine...not for me or one of my offspring...helping a friend.
 
Lowrider said:
Hey Skywalker!

I understand the swashplate and what it does but not the CCPM and I guess it doesn't matter since I'm not building a floppy wing flying machine anyway. From your comments I bought the wrong thing to test my servo and with yours and Beaver's guidance I think I'm on the right track now and will be able to move forward with installing the aileron servo and tab and actually test it's function. You guys have the "nuts and bolts" knowledge I lack in RC stuff and I appreciate your sharing that with me!!

One question...should the servo bellcrank only provide the movement on the control tab that will be appropriate to provide roll control at normal cruise speeds of around 130 mph? Best I can tell there is 180* movement possible from the servo shaft and I'd guess that it's probably only necessary to have less than 90* movement...will the controller accomplish this as I believe it will or will it move "lock to lock" on command? The servo seems to have plenty of power to give the tab all the movement it needs to tweak the aileron up of down.

Maybe I'm getting ahead of myself and this will become evident when I get the controller operating. Just don't want to get into the "chasing my tail" mode to get the proper of movement.
Click to expand...

With the Astro Controller you will be able to move the servo through its full range. It is proportional to the knob on the tester. I personally would have a linkage that works via a bellcrank to actuate your trim that way you can build in an adjustment that can be fine tuned if the servo ever needs to be replaced. Just my 2cts.


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That's the plan Beaver. Once I get a way to control the servo via the Astro I can make some estimates of how big the bellcrank needs to be and how to mount it within the aileron. I think I'll allow for adjustment at both the input and output sides of the bellcrank. The one for the elevator may be different in size but should function just the same...I think.
 
Hey Sky(wagon),

Now that we have the droop aileron set up in place what if any effect will the trim tab have on the overall function of the aileron when drooped? At slow speed? Should I plan to "undroop" when using the auto pilot?
 
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