RE: Yet another Sig Something Extra Build

RE: Yet another Sig Something Extra Build
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RE: Yet another Sig Something Extra Build - 3/6/2008 4:59:40 AM

iron eagel

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Joined: 7/15/2004
From: Middleboro, MA, USA
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Before I go much further I have to look at the landing gear issue. I have looked at TNT al gear that come in at about 2 oz, I have the Du-Bro #789 for .35-.61 size airplanes the Du-Bro come in at 4.6 oz, not all that bad but but as with the rest of the build I am looking for a lighter setup.
Does anyone know of a carbon fiber setup that is close to the size of the Du-Bro 3 5/8" at the fuse, 4.5" high with around a 12-14" width at the wheels that are lighter than the Al setup? Around an ounce max????

_____________________________

The Wrights never crashed, they only had hard landings. I 've had some hard landings myself. AMA EAA AOPA revver #185

(in reply to iron eagel)

Post #: 151

RE: Yet another Sig Something Extra Build - 3/15/2008 7:23:41 AM

iron eagel

Posts: 1060
Joined: 7/15/2004
From: Middleboro, MA, USA
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I wanted to post an update, I have had several distractions and have taken a few night off from building but have made some progress.

The tail feathers should be on the fuselage by tomorrow night. I have been working on the hinges and putting the carbon fiber veil on the rudder as I had mentioned earlier. All of the holes are drilled for the hinges and I need only to cut the notches in the elevator halves before the elevators are ready to get their veil treatment but I am going to wait until I have the fuselage and cowl complete and ready for covering before I do them. I just wanted to see how hard it was to apply the veil and what the results would be.

Wow is all I can say this stuff goes on easier than tissue and only after a few clear coats 3 to be exact I would say it is ready for paint. I have a few areas that need some very minor filling but that was an area I had damaged while handling. Oops!!!!
But what a smooth finish you can get fast! And as far as strength it takes considerable force to twist or bend the rudder! All up the rudder weighs .6 oz not bad….

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_____________________________

The Wrights never crashed, they only had hard landings. I 've had some hard landings myself. AMA EAA AOPA revver #185

(in reply to iron eagel)

Post #: 152

RE: Yet another Sig Something Extra Build - 3/15/2008 9:20:31 AM

alex7403

Posts: 550
Joined: 6/29/2004
From: New york, NY, USA
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Nice, so now you dont need the wires on the tail and its way stronger and lighter.

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measure twice cut once, again i cant believe i didnt learn it yet....

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Post #: 153

RE: Yet another Sig Something Extra Build - 3/15/2008 5:06:44 PM

WMB

Posts: 682
Joined: 10/5/2002
From: Great Falls, MT, USA
Status: online

"carbon fiber veil", Where do you get this? Do you have any good links for info on use and applications?
Thanks, MikeB

(in reply to alex7403)

Post #: 154

RE: Yet another Sig Something Extra Build - 3/15/2008 5:44:35 PM

iron eagel

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Joined: 7/15/2004
From: Middleboro, MA, USA
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quote:

ORIGINAL: WMB

"carbon fiber veil", Where do you get this? Do you have any good links for info on use and applications?
Thanks, MikeB

MIke,

I got the carbon fiber veil from a company called CST Sales.
http://www.cstsales.com/

Now as far as links I got the information from a buddy who does control line stunt, he was using it on a plane his is building for the Nats. this year. After seeing what it did to the piece of a fuselage he brought into work last fall I had to try the technique myself. It is very easy to do you cut a piece a bit larger then what you want to cover lay it on the sheathed surface and paint it down using clear dope and a brush. After two or three coats you use some 600 grit sandpaper to sand it smooth and then you can star on your finish coats of paint. Make sure that you have the balsa surface well sanded and ready to finish before you apply the veil or you will have to fill any defects before you finish coat of paint. Despite how stiff the fabric feels before it is applied it goes down real smooth with the clear dope. It will conform to curved surfaces very easy and trims easily with a razor blade after the dope drys. If you have to use more than one piece to cover a surface and overlap them it sands very easily and you will not have a ridge. I would look it up on one of the control line stunt site such as Pampa or alike for more info.

_____________________________

The Wrights never crashed, they only had hard landings. I 've had some hard landings myself. AMA EAA AOPA revver #185

(in reply to WMB)

Post #: 155

RE: Yet another Sig Something Extra Build - 3/15/2008 6:02:20 PM

iron eagel

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From: Middleboro, MA, USA
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Hi Alex,
Yes no tail braces needed on this Somethin Extra!

The tail came out only slightly lighter but that is not bad because the control surfaces are a lot larger than the stock ones. They are fully sheathed to boot and most of the finish is applied I will only be adding a few grams with the finish paint so they will be at least an ounce lighter than stock covered in monokote. And as I said the added strength is really neat considering how light everything came out. Hopefully tonight when I get home from work I can get the tail feather on the fuselage so it starts to look more like an airplane. I hope I can get the entire airframe to come in under 4.5 lbs still, but have yet to build up the cooling duct, cowl and fairings for the wing root. I have not received my composite gear I ordered last week so that will hold me up a bit on the cooling duct as the gear mount will be enclosed under it. I may just build up the cooling duct and allow for the fact I will have to let in the gear afterward. But I can still do the cowl, and wing fairings before I do the duct so I have work to go ahead with either way. Not to mention the wings and ailerons still need some work so I have enough to keep me busy ....

Your new build is coming along nice!

_____________________________

The Wrights never crashed, they only had hard landings. I 've had some hard landings myself. AMA EAA AOPA revver #185

(in reply to alex7403)

Post #: 156

RE: Yet another Sig Something Extra Build - 3/16/2008 6:11:16 AM

iron eagel

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From: Middleboro, MA, USA
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It seems like ages since the fuselage has had any addition made to it, tonight some real progress was made. I took a picture during the process of dry fitting of the tail feathers to the airplane. With the vertical stabilizer in position I wanted to show how the carbon fiber rods where anchored to the bottom of the fuselage. This is part of the modification to eliminate the need for, ugly and drag producing, external tail braces. After the preliminary checks for alignment of the components for both square and alignment to the center line, everything lined up perfectly. Sig’s laser cut kits makes it very easy to get the plane straight and true, and I was lucky enough that the parts that I built to substitute, with the carbon fiber spars fit ok.

Tonight I can report that the horizontal and vertical stabilizers are now finally part of the airplane. After everything set up I removed the clamps and took a picture, and wrote this.
Going to have a beer or two…

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_____________________________

The Wrights never crashed, they only had hard landings. I 've had some hard landings myself. AMA EAA AOPA revver #185

(in reply to iron eagel)

Post #: 157

RE: Yet another Sig Something Extra Build - 3/16/2008 2:23:57 PM

N1EDM

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From: Brockton, MA, USA
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That's really looking good, Paul. Can't wait to see it at the Field.

Bob

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An expert is someone who has been doing it for 15 minutes longer than you.

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Post #: 158

RE: Yet another Sig Something Extra Build - 3/16/2008 11:58:04 PM

iron eagel

Posts: 1060
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From: Middleboro, MA, USA
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I can not wait to see it at the field either....

Hand to make a trip over th Hanson Hobby to pick up some stock for the fairings and alike. The tail feathers are going have both fairings and fillets, probably overkill on this plane, but a good way to practice them before I do the scale ones I want to build. After the glue had time to cure this afternoon I tried stressing the horizontal and vertical stabilizer to see how my carbon fiber spars worked to eliminate the external tail braces. Nice and stiff no problem as far as strength that I can feel so it should work out nice. Normally when I have to cut the notch for the elevator joiner out of a tail fin like this model, I have some concern about weakening the structure, I do not see that being a problem here at all. You saw how the carbon fiber worked out on the rudder I brought to the meeting the other night, same thing here and I haven't applied the veil yet.
I am working on finishing the skin of the fuselage on the tail that I had left open so I could anchor the carbon fiber to the bottom of the fuselage then I will do the fairings and fillets.
Then the next step will be to start on the pressure cowling, and cooling duct. I ordered landing gear from TNT over a week ago but they have not turned up yet. And where they are going to be embedded within the cooling duct I really would like to have them here when I build that part. The cooling duct will be a bit more involved because it is going to have an expansion chamber and nozzle built into it. I want to see if Andy Lennon's theory about using thermal expansion from the waste heat of the engine to produce thrust works. From what I gather from reading his explanation is that it works somewhat like a ram jet.
Hey, if nothing else it will get the guys asking; "whats that all about" when they see it.

_____________________________

The Wrights never crashed, they only had hard landings. I 've had some hard landings myself. AMA EAA AOPA revver #185

(in reply to N1EDM)

Post #: 159

RE: Yet another Sig Something Extra Build - 3/17/2008 1:16:55 AM

N1EDM

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From: Brockton, MA, USA
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I see that you read Andy's book too. It's a shame that we don't have him around any more. I have the plans to a couple of his planes, but I don't know if I will ever get around to building them. He was quite the engineer.

You've got me thinking in terms of Carbon Veil now. I might just order some up to experiment with. I see that they also have fiberglass sheet too, and I've been trying to get some of that for general use....

I have often wondered whether those struts on the stock SSE were really necessary, but I really liked your approach to stiffening the structure with the CF rods. That was a great idea. I wish I had thought of something like that.

Bob

_____________________________

An expert is someone who has been doing it for 15 minutes longer than you.

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Post #: 160

RE: Yet another Sig Something Extra Build - 3/17/2008 5:41:27 PM

iron eagel

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From: Middleboro, MA, USA
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I would say that if you did not put the tail braces on or make changes to it and tried to fly the tail would fail during aerobatic flight. There is very little surface area that the horizontal stab sit on. Add to that that both the elevator and rudder are of a good size and the light balsa the plane is made out of simply would not hold up for long. The veil is awesome to work with, much easier than either silk span or tissue, I am impressed! But the real plus is that you have a very hard smooth surface for a painted finish fairly fast. After doing my wifes trainer with monokote I was not happy with how it came out and the plastic finish isn't all that light weight. While it might stick to the framework lets face it it does not add much strength for it weight, considering you can sheath, veil and paint, for about the same weight....

_____________________________

The Wrights never crashed, they only had hard landings. I 've had some hard landings myself. AMA EAA AOPA revver #185

(in reply to N1EDM)

Post #: 161

RE: Yet another Sig Something Extra Build - 3/18/2008 12:50:50 AM

N1EDM

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From: Brockton, MA, USA
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Hmmm, I wonder if there would be any benefit to putting veil under a fiberglass cloth finish, but now I'm getting off topic. We can talk about that off line.

Bob

_____________________________

An expert is someone who has been doing it for 15 minutes longer than you.

(in reply to iron eagel)

Post #: 162

RE: Yet another Sig Something Extra Build - 3/22/2008 4:57:20 AM

pt40crasher

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From: , CA, USA
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Re: the landing gear...I would add some beef to the fuse where they mount up. My gear ripped out early on when I hit a crack in the pavement and I've heard of others doing the same. I re-installed the gear and added some triangle stock and have had no further problems. $.02

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Post #: 163

RE: Yet another Sig Something Extra Build - 3/22/2008 5:59:55 AM

iron eagel

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From: Middleboro, MA, USA
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I am concerned about ripping out the gear myself, this setup along with the funtana and alike, with the longer gear put a lot of twisting force into the bottom of the plane in general. Then add to it I am getting gear which are a