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Author Topic: Thing III Build  (Read 2016 times)
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Konrad
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« Reply #50 on: August 07, 2017, 09:58:12 AM »

Don't tease us like that, Shocked what is the 3rd motor?
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Cut it twice and it's still too short!
steveair2
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« Reply #51 on: August 07, 2017, 11:30:41 AM »

Konrad, due to my inexperience with electric powered models, I keep ordering motors that are too heavy for my model.
The original Thing III weighed ten ounces and used a Cox .020 for power.
I think I can bring mine in at around eight ounces and am using the motor in the link below for power.

http://www.headsuphobby.com/HURC-300-Blue-Wonder-1600kv-Brushless-Motor_p_1980.html
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Konrad
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« Reply #52 on: August 07, 2017, 11:57:14 AM »

If you come in close to 8oz you will only need about 40 watts for real nice sport flying.  That blue wonder is a 100 watt motor (10amp x 11volts minus some inefficiencies).

For sport flying I like to aim for 50 watts to 100 watts per pound. I've flown with as little as 35 watt per pound but that was just to prove I could, really not much fun.

But as you will likely need more nose weight, the 25 gram motor should be fine. Just use a smaller prop and enjoy the run time. Motor , prop and battery selection is a science you will pick up soon. It actually is much easier than selecting the old glow power set up.
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Cut it twice and it's still too short!
steveair2
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« Reply #53 on: August 10, 2017, 03:04:50 AM »

Thanks much for your valued advice Konrad, I need all I can get.  I think my next task needs to be getting a quality soldering iron and getting a soldering station set up.
Also need to sort out my charging issues that I mentioned before.   Due to six and seven day work weeks, I put the charging issues low on my to do list.
It will happen soon.   

At Oshkosh, I attended a forum given by Barnaby Wainfan.  He designed the Thing III model and the Facet Mobile, a Low AR homebuilt airplane.
It was a very interesting discussion of low AR aircraft that has me wanting to build something similar to the Facet Mobile.
I really like the idea of a scaled up Thing III.

Even with the long hours at the plant, I'm also helping my friend Jim build a Legal Eagle.  Three days a month.

Now I'm getting the nose lengthened for the smaller, lighter motor and am repairing the old pushrod tube exit areas.
Getting close to final sanding!




   
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steveair2
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« Reply #54 on: August 12, 2017, 03:06:11 AM »

Boy,  Heads Up Hobbies likes me.  When I build a new model I order three or four motors for it.  I have the Blue Wonder mounted and am still having CG issues.
In this article http://library.modelaviation.com/ma/1994/12/thing-iii   Barnaby says to keep the tail as light as possible.  I did that by changing the solid control surfaces and lower fin and rudder to built up structures.  This article was from the early ninety's, so I'm not sure what type of radio and battery's that were used in his model.

In the article, he says he had to add a ounce and a half of weight to the nose to balance the model.   I've moved all my servos as far aft as possible and am still a bit nose heavy.  Now I'm planning on taking the Blue Wonder motor off and using yet a smaller motor and battery combination.  The funny thing is that I have had the smaller motor for a year or more on another model that has not flown yet.  It's only two tenths of an ounce lighter, but the lighter battery will help as well.

The motor I'm installing next is this one  

http://www.headsuphobby.com/HURC-250-Sport-1400kv-Outrunner-Brushless-Motor_p_1589.html

 
« Last Edit: August 12, 2017, 03:26:51 AM by steveair2 » Logged
OZPAF
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« Reply #55 on: August 15, 2017, 02:07:50 AM »

That should work ok Steve. I assume you will be running a 2s battery pack as they recommend for your weight range with a 8x4 prop?

John
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steveair2
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« Reply #56 on: August 19, 2017, 10:57:31 PM »

Thanks very much for your input John.  We've been working seven days a week at the plant in the Texas heat.  All my projects are going slow.
I missed a few pictures of my canopy mold.   To get the width I wanted, I had to glue two, two by fours together.
Trimmed the block down on the table saw, band saw and belt sander.   I also did some work on the nose gear mount and the lower vertical stabilizer mount.

 
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