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Old Jan 09, 2002, 04:47 PM
Fixed Wing Fanatic
Jim Walker's Avatar
United States, TX, McKinney
Joined Jul 2001
2,344 Posts
Take my Tiny out of retirement?

I built a Tiny from a kit from Todd's models 8 months ago. I bought all the expensive goodies for it that Todd recommended. The goody list included:

DC1717
JMP HF9 high frequency ESC
Braun prop
GWS micro servos
Feather reciever

I built a 9 X 120mah Nimh battery for it. It came out a little heavy at 4.75 ounces because it was one of the last Bill Griggs manufactured kits. The wood was pretty lousy, but that's another story..... During my total of 6 or 7 flight attempts, I was getting major glitching which caused several hard nose in's. Bye-bye $30 Braun prop. I asked what might be wrong on several forums knowing my reciever was fine, but recieved no answer. A recent thread finally revealed that the carbon fiber boom causes interference unless the antenna is routed away from it. I had mine running down the boom and off the tail as I do on all my small planes. One problem solved!

Next problem, during my flights that didn't end in a glitch induced crash, the plane was horribly under powered and would only sustain flight for about half the discharge cycle of the cells. After trying the TNR 120mah nimhs in several planes and taking some measurements, it is clear that these cells are only good up to one amp. After that the voltage drops off dramatically and thus thrust. My recent tests showed that under load, 10 X 120mah nimhs were out performed dramatically by 6 X 110mah nicads or 5 X 300 nicads. Of course the two nicad packs weigh about 30% more even though they contain fewer cells. So..... this problem is understood but not resolved. What cells and how many of them are best for the Tiny and the DC1717??

Last problem, I built my Tiny with the V-tail and ailerons. The V-tail is linked together and just acts like an elevator, so the controls are really elevator and ailerons inspite of the V-tail. When I balanced my Tiny according to the plans, it tested out slightly tail heavy. I went ahead and tried flying it with this CG. Amazingly it acts severly nose heavy. I have to trim in a good amount of up to get it to fly straight and level. This causes the plane to take a big dive when I try to do multiple rolls. Still don't understand this one nor how to correct it. As far as I can tell the incedences are all right on.

If somebody could help me to choose some good cells for this bird and point out what might be causing it's nose heavy behavior, I might just dust it off, get another prop and give it a try. I've heard nothing but good things about Tinys, so I feel like I'm missing out here.

Thanks in advance............Jim Walker
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Old Jan 09, 2002, 05:01 PM
Registered User
United States, MA, Waltham
Joined Dec 2001
7,109 Posts
Be skeptical about carbon causing your glitches as I've seen planes fly fine with antenna running along carbon boom. Maybe because they were dual conversion receivers.

I understand that some nimh are better than others. I think the double time cells from John Worth are supposed to be ok, aren't they?

On the nose heaviness, do you have a lot of downthrust? Does it still do this at low power?
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Old Jan 09, 2002, 05:09 PM
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nolasco's Avatar
New York, NY
Joined Dec 2000
1,297 Posts
Are you using those NiMh cells in the cold? If so, that could be one cause. I myself can't get more than two minutes of flying time on those cells in this freezing weather. And that's with a 3oz plane.

You might want to use 50mah NiCd cells instead. They ought to provide more oomph! than the NiMh cells.

I myself have given up for a while on those tiny NiMh cells for the duration of winter. Unfortunately, my 50mah NiCd packs haven't arrived yet.

Jun Nolasco
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Old Jan 09, 2002, 06:34 PM
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dgoslee's Avatar
Seaford, DE
Joined Jan 2002
793 Posts
Jim:

I have the exact same setup as you, except a ARC-1 prop instead of the Braun.

1) Glitching- mine didn't glitch at all with the antenna running down the carbon rod and rubber banded to the tail. To keep all that wire from dragging behind, I ran it out the wing through the rib lightening holes in front of the spars, came out the tip, and went back in down the set of lightening holes in back of the spars. I didn't range test it and flew it, and it glitched so bad I almost wrecked it. I pulled it back out, attached it back to the tail, and it worked fine.

2) Mine weighs 5.37 oz with 9 double time cells (120 mah NiMH). It has noticably more power than with (8) 50 mah cells. It has plenty of power for outdoor flying.

3) I also had the V-tail - aileron mixing. It would dive during rolls. Let's say your doing a left roll. As you roll over 90 degrees, and your holding left aileron, the V-tails are also left, which at 90 degrees is like having down elevator so it dumps the nose (If you were doing a left banked knife edge, you would want to hold right rudder to hold the nose up, but the mixing gives you left). The first roll I tried, I almost hit the ground because as soon as it rolled over it was pointing straight down. I unhooked the mixing.

Dan
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Old Jan 09, 2002, 07:07 PM
Been There! Done That!
boomerace's Avatar
Eugene, Oregon, United States
Joined Sep 2001
19,187 Posts
I've had several planes that glitched with the antenna next to the carbon rod... one was my Tiny w/M100 power. In both cases running the Azaar antenna down the wing solved the problem! Works for me!
boomer
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Old Jan 10, 2002, 11:20 AM
RAF
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Indiana
Joined Dec 2001
12 Posts
This seems like a good place for my first post.
Almost two years ago I scratch built a Tiny and used exactly the same equipment, feather antenna is taped to the carbon boom.
Never had a problem, even flew indoors once with 6 or 7 other craft in the air.
Mine is built with the v tail, coupled and mixed as described on the plans, The v tail works great for slow fly control but not so for aerobatics.
When I built mine I didn't have the carbon tubes so I used a Dave Brown push rod for the boom, old broken graphite flyrod tips for the long push rods and music wire landing gear and still came out at 5 oz with the lithium cr2's that I usually fly with.
I like this Tiny so much that I just finished two new ones, one with a v tail and one with conventional tail.
My Tiny requires a lot of elavator input when inverted.

My goal for the new ones is to shave off an oz. auw, Looks like I'm going to make it, or very close to it.

I am using the original Braun prop, the design seems to allow the blades to depart the shaft without damage, just re glue.
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Old Jan 10, 2002, 11:38 AM
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Jim Walker's Avatar
United States, TX, McKinney
Joined Jul 2001
2,344 Posts
Thank you all for your replies......


Lincoln,

I've heard that John Worth's brand of 120mah nimhs are better than most, but I'm skeptical after trying TNR's. I spent $50 buying 25 cells to get the good price and they are just sitting there with no application for me. I'm sure they would work great for indoor applications like KP00's, N20's, firefly's and such. What I need though is the lightest cells I can find that will deliver 1.5-1.75 amps with out dropping their voltage severely. Duration is not a concern, I just want something that works without having to add an ounce to my Tiny.

Nolasco,

The flight attempts I spoke of were in the middle of summer, so that wasn't a factor. However I definitely agree that Nimhs are a pain in the winter. I almost gave up on them too. What I finally discovered is that you have to get them up to room temperature at the field and then charge them. Even if you charged them the night before, you have to top them off right before your flight and fly them immediately after charging. Even a wait of 5 minutes kills the whole procedure because they cool off again. Using this method I get close to summer performance out of my Nimhs.

Dgoslee,

Is your Tiny powered by a DC1717??? If it is, then my 120mah nimhs are worse than I thought. With mine weighing over a half ounce lighter and using the same number of cells it was a dog! I wondered if 50mah nicads were any better than 120mah nimhs, they are so small. I've yeahs and nays on them and that's the reason I haven't bought any. Were did you get your 120's that perform so well?? I had mine mechanically mixed for the first flight too. I experienced exactly what you said and called Todd. He told me to hook up the V-tail as an elevator if I wanted to do aerobatics. I did so and could then do a couple of rolls before it nosed in, however, if I tried for roll three it was "crash-o-mundo".

Please keep the suggestions coming and thanks again!!
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Old Jan 10, 2002, 03:18 PM
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Paul Penney's Avatar
Ancaster, Ontario, Canada
Joined Nov 2000
2,525 Posts
RAF,

WELCOME to the E-zone! your virtual home for electric flight

and now the serious part....

I believe you should try a GWS reciever, Feathers have been known to THOROUGHLY glitch!
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Old Jan 10, 2002, 03:45 PM
RAF
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Indiana
Joined Dec 2001
12 Posts
Quote:
Originally posted by Buddly6
RAF,

WELCOME to the E-zone! your virtual home for electric flight

and now the serious part....

I believe you should try a GWS reciever, Feathers have been known to THOROUGHLY glitch!
Buddy

I have a GWS flight pack in a new TM that santa brought me for Christmas and a GWS flight pack in a Pico Cub that santa brought for my son.

I have been flying the Feather radio in the Tiny for almost two years and never been glitched yet so I can't complain.

My TM has about a dozen flights on it now and flies great, I did most of the mods I found here, great web site.
The Cub is a piece of cake.
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Old Jan 10, 2002, 08:10 PM
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ckoerner's Avatar
Crest Hill,Il
Joined Oct 1999
200 Posts
Feather

I had a feather on my Tiny and I got very bad glitches with other radios on. When I flew by myself I had no glitches. I changed to a GWS and have no problem. I have my antenna running down the carbon rod with no problems. Yes the props do get expensive.
Later,
Craig
www.circad.com/craig
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Old Jan 10, 2002, 09:30 PM
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dgoslee's Avatar
Seaford, DE
Joined Jan 2002
793 Posts
Jim

Yes, DC1717, HF-9 speed control, ARC-1 prop.

The 120 NiMH cells were bought from Cloud 9 (Double-Time cells). The came as individual cells with a short lengths of wire already soldered to them. I had to de-solder all these wires prior to putting the packs together.

Dan
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