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"Prototype T.D. .010 c.1960"



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Modified SIG Twister

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Modified SIG Twister

Post  Cribbs74 on Tue Mar 11, 2014 10:42 pm

I didn't want to step on Jim's toes and post my build into his log so I decided to start a new one. Here is the rough cut, doesn't look like much at the moment. I added 2" to the tail and cut off 1" from the nose. Power will be an O.S. .40FP or maybe an Enya .45. 6001. Not sure yet, but I am leaning towards the O.S.

It won't look anything like a Twister or even a Fancherized Twister when it's done. Yes I know I should be working on the speed plane...

Ron





Last edited by Cribbs74 on Fri Aug 18, 2017 1:57 am; edited 2 times in total
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Re: Modified SIG Twister

Post  Mark Boesen on Tue Mar 11, 2014 11:25 pm

Hey, make a Banshee out of it, lol!

Lookin good!

I did stop off at Office Depo and get plans for my Shoestring enlarged, so that is a step forward.
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Re: Modified SIG Twister

Post  OVERLORD on Wed Mar 12, 2014 2:19 am

Very clean build Ron. Are you going to box the TE? It'll make it strong and difficult to twist.

Lieven
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Re: Modified SIG Twister

Post  WingingIt74 on Wed Mar 12, 2014 2:11 pm

Twisted Sister?  lol! 













Edited by Rusty... Revived the video
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Re: Modified SIG Twister

Post  Cribbs74 on Wed Mar 12, 2014 2:22 pm

What a ridiculous decade....my daughter thinks it's cool that I grew up in the 80's. I should show her this video.
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Re: Modified SIG Twister

Post  WingingIt74 on Wed Mar 12, 2014 2:29 pm

Cribbs74 wrote:What a ridiculous decade....my daughter thinks it's cool that I grew up in the 80's. I should show her this video.

Ya, but I do like the song and band though Smile
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Re: Modified SIG Twister

Post  WingingIt74 on Wed Mar 12, 2014 2:36 pm

Both my Sons are into Atari, Sega and Nintendo from the 80s-90s, they say the games are more fun from back then Smile

Sorry for the hijack, I seen the name of your thread and Twisted Sister popped in my head... proceed kind sir Smile
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Re: Modified SIG Twister

Post  Cribbs74 on Wed Mar 12, 2014 4:11 pm

No worries
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Re: Modified SIG Twister

Post  Ken Cook on Wed Mar 12, 2014 4:19 pm

Ron, I'm not sure if your aware of this particular wing having half ribs. This is one modification I would truly do. Installing 1/2 ribs from the spars to the leading edge in between the stock ribs helps this plane immensely. The rib spacing is too far apart allowing the covering to really sag in between. You could easily stand the wing up on end and get a pattern and then stack cut a few of them. Another thing is to install vertical grain 1/16th in between the ribs on the back of the spars from top to bottom for a few bays from the center of fuse outwards towards both tips. Ken
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Re: Modified SIG Twister

Post  Cribbs74 on Wed Mar 12, 2014 5:39 pm

Ken,

I'll probably do the 1/2 ribs as you suggest. I am having a little trouble picturing the other modification you suggested.


Ron
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Re: Modified SIG Twister

Post  RknRusty on Wed Mar 12, 2014 7:19 pm

Ken Cook wrote:... Another thing is to install vertical grain 1/16th in between the ribs on the back of the spars from top to bottom for a few bays from the center of fuse outwards towards both tips. Ken
Cribbs74 wrote:Ken,

I'll probably do the 1/2 ribs as you suggest. I am having a little trouble picturing the other modification you suggested.

Ron
Like shear webs I think. To stiffen the wing as it extends out from the root.


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Re: Modified SIG Twister

Post  Cribbs74 on Wed Mar 12, 2014 8:15 pm

Ah! I get it, pretty cool. Thanks Rusty!

Ron
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Re: Modified SIG Twister

Post  GUS THE I.A. on Wed Mar 12, 2014 8:45 pm

I put the nose ribs on my Fancherized Twister, and I think it helps maintain the airfoil. Besides, it looks cool.
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Re: Modified SIG Twister

Post  pkrankow on Wed Mar 12, 2014 10:33 pm

Those shear webs are better installed so they exactly fit the spar spacing, and are centered on the underside of the spar. The reason is the same as why I beams are used in structures instead of C beams. The C configuration puts a twist on the spar under load, where the I configuration does not.

Now, how much of a practical difference is this?

Good question. I decide my answer when I build. I have built both I and C configurations with excellent results, but I still crash a lot.

Phil
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Re: Modified SIG Twister

Post  Cribbs74 on Wed Mar 12, 2014 10:40 pm

Thanks Phil,

So what you are saying is they should be in between the spars and not the outside?

Ron
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Re: Modified SIG Twister

Post  RknRusty on Wed Mar 12, 2014 10:44 pm

The I beam is definitely stronger than the C. But if the C will do an adequate job of stiffening, perhaps it would just let go and cause less destruction in a crash? Wondering out loud.
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Re: Modified SIG Twister

Post  Ken Cook on Thu Mar 13, 2014 4:19 am

Ron, I personally see no  advantage to placing the shear webbing within the spar area. The bottom line is that you should have them and  place them at least to the middle of the wing approx 4 bays out towards the tip.  True a I beam is strong, but the shear webs and glue stop the spars from flexing and in the event of terra firma, the webs being placed on the outside can be sacrificial saving the spars as they will just crack or  pop off. They're stong enough as is and that's all that you need which is far more than what the original kit offers. Flex the wing over your knee prior to installing these and then do it afterwards. You will note the strength advantage.  Lieven mentioned this above by doing this to the trailing edge as well. Depending on wood selection, I like to do this to every bay of the trailing edge by gluing the pieces from top to bottom of the trailing edge sheets. I've done this where you made the pieces go within the opening but it's very time consuming and not necessary. Many of us have avoided this step by just swapping out the stock spars and leading edge material on the Twister for spruce. Ken
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Re: Modified SIG Twister

Post  Surfer_kris on Thu Mar 13, 2014 6:20 am

One advantage of placing the shear webbing between the spars, as I see it, is that you do not rely on the glue to do all the job...

Plus, as mentioned before, the I beam will bend symmetrically. On the other hand, one could possibly get the C-beam to twist the wing in the right direction (to give washout) under load...  Huh... 
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Re: Modified SIG Twister

Post  JPvelo on Thu Mar 13, 2014 7:07 am

Ken Cook wrote:Many of us have avoided this step by just swapping out the stock spars and leading edge material on the Twister for spruce. Ken
The leading and trailing edges of my Twister were so twisted I replaced them with basswood.

Jim
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Re: Modified SIG Twister

Post  Cribbs74 on Thu Mar 13, 2014 1:43 pm

JPvelo wrote:
Ken Cook wrote:Many of us have avoided this step by just swapping out the stock spars and leading edge material on the Twister for spruce. Ken
The leading and trailing edges of my Twister were so twisted I replaced them with basswood.

Jim

Probably not a bad idea. Mine were terrible as well. I should have replaced the wood. Oh well, not turning back now.

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Re: Modified SIG Twister

Post  Cribbs74 on Sun Apr 06, 2014 7:14 pm

Here is a little update.

I installed the beam mounts and created a fin/rudder more to my liking. I will work on the shear webs and half ribs next. The .40FP is rubber banded to the nose. Looks like I will have to cut more area between the mounts to slide the engine back.

This thing feels heavy already. I am not happy about that. I'll weigh it and see.

Ron




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Re: Modified SIG Twister

Post  roddie on Sun Apr 06, 2014 7:39 pm

Is that an MGA sitting there Ron?  Shocked
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Re: Modified SIG Twister

Post  JPvelo on Sun Apr 06, 2014 7:50 pm

Ron,
I added three inches to the tail of my twister and left the nose the same length. I came out tail heavy and am using a 2oz prop hub to balance properly. Before moving the engine back I would consider cutting new ply doublers that will accomadate a filler behind the engine. You will want to replace the kit supplied ply anyway, at least on the outboard side.

Jim
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Re: Modified SIG Twister

Post  Cribbs74 on Sun Apr 06, 2014 8:39 pm

Jim,

I added 2" to the rear and cut off one from the front. Not sure where that puts me. I guess in reality that is 1" extra in the back end.

I'll keep that in mind Jim. You used the the FP correct?
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Re: Modified SIG Twister

Post  Cribbs74 on Sun Apr 06, 2014 8:40 pm

roddie wrote:Is that an MGA sitting there Ron?  Shocked

Yes sir, 1958 fresh  Laughing 
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Re: Modified SIG Twister

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