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Old Feb 17, 2013, 10:22 PM
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Doug Bartley's Avatar
Canada, ON, Owen Sound
Joined Oct 2008
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Hi Dangaras: The bomb drop worked pefect yesteerday. I decided to play with it!! When I opened the bombay doors, the bombs fell out - wthgh!!
After some testing, I found out the opening of the doors made the bomb release servo jum[ back and forth, enough to release.
My first thought was I need to rebind the radio, did that, with no improvement.
Whilewatching the bomb servo, the door servo decided it had enough, and went up in smoke\\!!!! I just installed it yesterday. Apparently it had pressure against it in the up position enough to fry, it actually caught fire.
Gutted that servo out, remade the arm to lock up so no tension, then started over again. Testng for 15 minutes power on had this servo ice cold. I may have this part licked.
Turns out the bomb release servo was defective, replaced it with same type, and it worked fine.
And here I was thinking the Retracts where my big problem!!!!! EVERYTHING CONNECTED TO THIS DA....D PLANE IS A PROBLEM!!!
I'm beginning to really dislike Mosquito's!! hehe
Oh yes, no room for a plastic spring, the pocket for the rear bomb mount is tapered, the dowel is round, it cannot catch or hang up. Now that I've said that, it will!! Doug B
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Old Feb 17, 2013, 10:47 PM
Jack of all master of none
splinterz25's Avatar
Baltimore MD USA
Joined Jan 2011
4,608 Posts
Looks great Doug very simply done.
Keep up the good work,

Bruce
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Old Feb 18, 2013, 02:45 AM
...design-build-fly-publish...
eye4wings's Avatar
Ware, herts. U.K.
Joined Sep 2008
3,519 Posts
Doug, I am not planning a full build log on the Caribou - I am just extending Old Whitebelly's thread since that was where I found most of the info I needed. I'll be showing salient points I expect, but my editor doesn't like to be offered everything that has already been seen. This will be tasters only until full publication after which I can always provide info extra to what he published.
http://www.rcgroups.com/forums/showt...411598&page=12

I am planning on doing the undercart and flaps 'properly' that is, as close to scale as I can get and as I want to get that really slow approach and wheelbarrow capability am using some foam for my first time. I have not seen any other Caribou models that do that so am trying to break new ground!

Also using foam wheels to aid the lightness, so am hoping not to notice the trim change you mention.

As things are at present I am well aware that your engineering is far better than mine (what can I expect when I only have carpentry hand tools?!) so am watching your present struggles with trepidation knowing that I've been here before and remembering the pain. You get to the point where the major impetus to trying yet again is the desire not to waste all the work already put in.

Of course once success is achieved the sense of relief is great!
Going for an MA yet again - Master of the Art - or Masochists Anonymous - maybe both!
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Old Feb 18, 2013, 09:20 AM
Dont be divided from the truth
Dangaras's Avatar
Canada, ON, Toronto
Joined Mar 2010
3,331 Posts
Quote:
Originally Posted by Doug Bartley View Post
Hi Dangaras: The bomb drop worked pefect yesteerday. I decided to play with it!! When I opened the bombay doors, the bombs fell out - wthgh!!
After some testing, I found out the opening of the doors made the bomb release servo jum[ back and forth, enough to release.
My first thought was I need to rebind the radio, did that, with no improvement.
Whilewatching the bomb servo, the door servo decided it had enough, and went up in smoke\\!!!! I just installed it yesterday. Apparently it had pressure against it in the up position enough to fry, it actually caught fire.
Gutted that servo out, remade the arm to lock up so no tension, then started over again. Testng for 15 minutes power on had this servo ice cold. I may have this part licked.
Turns out the bomb release servo was defective, replaced it with same type, and it worked fine.
And here I was thinking the Retracts where my big problem!!!!! EVERYTHING CONNECTED TO THIS DA....D PLANE IS A PROBLEM!!!
I'm beginning to really dislike Mosquito's!! hehe
Oh yes, no room for a plastic spring, the pocket for the rear bomb mount is tapered, the dowel is round, it cannot catch or hang up. Now that I've said that, it will!! Doug B
Doug,
I think she is testing you, trying to make sure you really want to have a long term relationship with her! Did you bring her chocolate & roses on the 14th?

Sounds kind of like all the fun I have had with all 3 of my favorite girls, the mozzie, A-26 & the bashed h9 corsair!

Gotta struggle with every damned neat feature I added! That or sell them off...

At least what you are doing is giving the rest of us some really neat new things to try and someone who is going to be the goto expert to get them going!
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Old Feb 18, 2013, 10:02 AM
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Doug Bartley's Avatar
Canada, ON, Owen Sound
Joined Oct 2008
2,874 Posts
Quote:
Originally Posted by eye4wings View Post
Doug, I am not planning a full build log on the Caribou - I am just extending Old Whitebelly's thread since that was where I found most of the info I needed. I'll be showing salient points I expect, but my editor doesn't like to be offered everything that has already been seen. This will be tasters only until full publication after which I can always provide info extra to what he published.
http://www.rcgroups.com/forums/showt...411598&page=12

I am planning on doing the undercart and flaps 'properly' that is, as close to scale as I can get and as I want to get that really slow approach and wheelbarrow capability am using some foam for my first time. I have not seen any other Caribou models that do that so am trying to break new ground!

Also using foam wheels to aid the lightness, so am hoping not to notice the trim change you mention.

As things are at present I am well aware that your engineering is far better than mine (what can I expect when I only have carpentry hand tools?!) so am watching your present struggles with trepidation knowing that I've been here before and remembering the pain. You get to the point where the major impetus to trying yet again is the desire not to waste all the work already put in.

Of course once success is achieved the sense of relief is great!
Going for an MA yet again - Master of the Art - or Masochists Anonymous - maybe both!
Hi Robin: I will not quit and refuse to give up. Going thru a real learning curve here. So far, I bought 8 servos for the LG, including the 2 on their way now.
Thanks for the link to the Caribou. Can't wait to see you try the "wheelbarrow". Doug B
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Old Feb 18, 2013, 10:08 AM
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Doug Bartley's Avatar
Canada, ON, Owen Sound
Joined Oct 2008
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Quote:
Originally Posted by Dangaras View Post
Doug,
I think she is testing you, trying to make sure you really want to have a long term relationship with her! Did you bring her chocolate & roses on the 14th?

Sounds kind of like all the fun I have had with all 3 of my favorite girls, the mozzie, A-26 & the bashed h9 corsair!

Gotta struggle with every damned neat feature I added! That or sell them off...

At least what you are doing is giving the rest of us some really neat new things to try and someone who is going to be the goto expert to get them going!
I never dreamed I'd be having this much trouble with the LG. It is a fairly simple system, apparently very touchy about endpoints. These new super sensitive servos only aggravate this. The last incident was completely my fault, one LG has to set electronically, the other MUST be set mechanically unless you use 2 dedicated channels. If I didn't want bombs and the bombay, I definetly go that way. I'll get it done, I want this to fly!! Maybe I'll have to sacrifice a small plane, or a dead chicken -hehe. Doug B
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Old Feb 18, 2013, 10:14 AM
I don't want to "Switch Now"
pmackenzie's Avatar
Toronto (Don Mills), Canada
Joined Dec 2002
17,099 Posts
This is one advantage of retract servos - big deadband.
With some digitals you should be able to program the deadband so they are not so picky. And you could also set the endpoints of each independently.
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Old Feb 18, 2013, 11:44 AM
Dont be divided from the truth
Dangaras's Avatar
Canada, ON, Toronto
Joined Mar 2010
3,331 Posts
Quote:
Originally Posted by Doug Bartley View Post
I never dreamed I'd be having this much trouble with the LG. It is a fairly simple system, apparently very touchy about endpoints. These new super sensitive servos only aggravate this. The last incident was completely my fault, one LG has to set electronically, the other MUST be set mechanically unless you use 2 dedicated channels. If I didn't want bombs and the bombay, I definetly go that way. I'll get it done, I want this to fly!! Maybe I'll have to sacrifice a small plane, or a dead chicken -hehe. Doug B
Definitely the chicken!
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Old Feb 18, 2013, 12:50 PM
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Doug Bartley's Avatar
Canada, ON, Owen Sound
Joined Oct 2008
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Quote:
Originally Posted by pmackenzie View Post
This is one advantage of retract servos - big deadband.
With some digitals you should be able to program the deadband so they are not so picky. And you could also set the endpoints of each independently.
I heartily agree that a retract sero would be the way to go. If I was starting again, I would use these. The problem here is that most RS's don't have enough power, most are around 6 kg's, only the JR791 is powerful enough, at $60+ each!!
As of now, it would involve a complete restructuring of the entire LG system, that would probably mean stripping down the nacelles to their basic frame, something I'm not willing to do at this point.
The sytem worked fine with 10kg analog servos as originally tested. I thought to be on the safe side, I'd use a stronger unit, went with 12.5kg units. The unfortunate collapse of the gear took those out (my fault). I then swtiched to digital at 16 kg, and again I failed to take enough care in the setup, resulting in another burnt servo. I found out what had gone wrong by retesting the still operating unit, it works fine with no stress on the servo (read no heat buildup), servo stays cold. The MI digital servos now on the way have 27kg torque, much slower speed (read lower gearing), and magnetic positon sensing. They should offer the resistance required with no load on the electric side. I hope We'll see. Doug B
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Old Feb 18, 2013, 12:52 PM
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Doug Bartley's Avatar
Canada, ON, Owen Sound
Joined Oct 2008
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Originally Posted by Dangaras View Post
Definitely the chicken!
I had chicken for supper last night, does that count - hehe. Doug B
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Old Feb 18, 2013, 02:43 PM
...design-build-fly-publish...
eye4wings's Avatar
Ware, herts. U.K.
Joined Sep 2008
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Doug, my favourite 180 degree retract servo is the SuperTek 136GH, which has the slowest movement of all I have fouund but still far too fast at 1.5 secs end to end. From memory it is about 11 lb, commensurate with its slowness and costs just under 18 over here - though I notice they seem to be becoming harder to get.

No way to slow them down though .

Incidentally an old thread may have more info that may be helpful...
http://www.rcgroups.com/forums/showthread.php?t=925400
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Old Feb 18, 2013, 05:26 PM
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Canada, ON, Owen Sound
Joined Oct 2008
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Hi Robin\; Thanks for the info on the servo. It unfortunately is nowhere near strong enough for this application. At 11lbs/5kg it is about 1/2 of what is required. I used a 10kg first, and it worked, but sounded like it was working harder than I wanted.
My 9303 JR radio has servo slow built in, all that does is reduce the power of the servo from my point of view. It may not actually, but the servo sounds so bad I can't convine myself to run them there.
As you other site shows, its all in the gearing! Most of what I've tried are around .15sec for 60 degrees. With travel adjusted to about 90-95 degrees and the servo slow set at 1.5 sec, it takes about 2 seconds.
I've ordered 27kg servos, with a speed of .19 on 6v, far deeper gearing so I expect travel to be in 2- 3 second area. These may have the power to be slowed even more, or they will just break stuff - hehe.
I need the doors to open right now, normal speed, wheels down in 2-3 seconds. For retracting, doors are set at 3.5 seconds while the wheels are 2 sec. Any setting can be changed to a max of 15 seconds!!
Careful adjustment of the lockup should avoid any more issues with "torchy" servos. I'm not too worried about the slow travel like scale, more interested in something that works everytime. Doug B
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Old Feb 18, 2013, 07:55 PM
Now in TN!
J Morgan's Avatar
Chapel Hill, TN USA
Joined Apr 2001
24,764 Posts
Hang in there Doug, you'll get it. You certainly have a great attitude about it. I would have been stomping up & down on it by now.

J
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Old Feb 18, 2013, 11:58 PM
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Doug Bartley's Avatar
Canada, ON, Owen Sound
Joined Oct 2008
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Originally Posted by J Morgan View Post
Hang in there Doug, you'll get it. You certainly have a great attitude about it. I would have been stomping up & down on it by now.

J
THE THOUGHT HAS CROSSED MY MIND - MORE THAN ONCE!! HEHE.
I have far too much of my life invested in the Mossy now, and my daddy didn;t raise no quitters. I'll get her done.
I'd be a lot more upset if I hadn't realized that is was ME that messed up, I need to think thru each step here more carefully.
I'd better get this sorted out, my bud is digging out the paint compressor this week. Doug B
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Old Feb 19, 2013, 05:27 AM
...design-build-fly-publish...
eye4wings's Avatar
Ware, herts. U.K.
Joined Sep 2008
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Bit surprised that servo I suggested can't do one wheel... I had all three of my home-build goldberg-alike legs on my Meteor hooked up to one centrally mounted one. Did the job... though I did use a spring compensation to get it over the sticking points.
My surprise is that your engineering is excellent whereas mine is... well, not, but you still need that kind of muscle to do the job!

A spring would certainly help whatever servo is used - and is my best suggestion - see below for a quick sketch.

When down the spring is in line (very closely) with the main leg and therefore offers very little resistance to movement either way. Although fully extended its power is absorbed in compressing the main leg. Once started on retraction the arc of movement means that more of the spring's power is assisting the retraction until the gear is fully up, at which point the shortened spring has released its pull significantly and therefore offers little resistance to the beginning of the gear down phase.
The point at which the gear should balance without assistance is up to each to decide as would be the guage and strength of spring needed to achieve balance.

But I'm sure you must know all this - and perhaps have some reason for not doing it that I cannot see.
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