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Yet another Sig Something Extra Build

Old 03-05-2008, 11:59 PM
  #151  
iron eagel
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Default RE: Yet another Sig Something Extra Build

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????

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Old 03-15-2008, 01:23 AM
  #152  
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Default RE: Yet another Sig Something Extra Build

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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Old 03-15-2008, 03:20 AM
  #153  
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Default RE: Yet another Sig Something Extra Build

Nice, so now you dont need the wires on the tail and its way stronger and lighter.
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Old 03-15-2008, 11:06 AM
  #154  
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Default RE: Yet another Sig Something Extra Build

"carbon fiber veil", Where do you get this? Do you have any good links for info on use and applications?
Thanks, MikeB
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Old 03-15-2008, 11:44 AM
  #155  
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Default RE: Yet another Sig Something Extra Build


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.
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Old 03-15-2008, 12:02 PM
  #156  
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Default RE: Yet another Sig Something Extra Build

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!
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Old 03-16-2008, 12:11 AM
  #157  
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Default RE: Yet another Sig Something Extra Build

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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Old 03-16-2008, 08:23 AM
  #158  
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Default RE: Yet another Sig Something Extra Build

That's really looking good, Paul. Can't wait to see it at the Field.

Bob
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Old 03-16-2008, 05:58 PM
  #159  
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Default RE: Yet another Sig Something Extra Build

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.
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Old 03-16-2008, 07:16 PM
  #160  
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Default RE: Yet another Sig Something Extra Build

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
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Old 03-17-2008, 11:41 AM
  #161  
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Default RE: Yet another Sig Something Extra Build

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....
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Old 03-17-2008, 06:50 PM
  #162  
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Default RE: Yet another Sig Something Extra Build

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
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Old 03-21-2008, 10:57 PM
  #163  
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Default RE: Yet another Sig Something Extra Build

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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Old 03-21-2008, 11:59 PM
  #164  
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Default RE: Yet another Sig Something Extra Build

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 an inch over stock so I can use at least a 12" prop without getting a strike on a grass field. The lever action on the gear will want to twist the gear plate out of the bottom of the fuselage. I hope that what I have already done to it will be enough, I really hate to add a lot of more weight to it, my cooling duct is also going to have to be added to the equation also.
I am working on the cowling right now.
I have the motor mounted up and am working on templates for the cowl and baffles in it. I am still trying to figure out how to stuff the exhaust system within the cowl and cooling duct. I have not found anything off the shelf that I can use for an exhaust header, that will fit in the cowl and allow me to run a pipe back within the cooling duct. The engine is mounted inverted so that adds a bit of a twist to the whole thing. Right now trying to mill a chunk of brass with a drill and a dremmel seems to be the only option I have, and I do not want to spend money on another engine right now.

But all that aside, the cooling duct has some structure that I hope will add some more strength to the gear setup but I am still waiting on the gear from TNT before I can even start on the duct at this point.

I posted this picture earlier take a look at what I added and see what you think about the gear plate mounting...

edit to add:
The gear will also have some support from the cooling duct, I added a sketch that shows the structure of the duct.
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Old 03-22-2008, 12:25 AM
  #165  
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Default RE: Yet another Sig Something Extra Build

Bob,
I had to think about that for a bit...
If you are going to need the strength of fiberglass over the veil seems like you should go to some "very thin" woven carbon fiber mat.

I'll give you some veil to experiment with who knows ???
Might be worth looking into if you are thinking putting the veil on with dope, to keep the epoxy from sinking into the balsa, when you glass you might be able to reduce the weight and still have it bond to the airplane.
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Old 03-22-2008, 07:44 AM
  #166  
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Default RE: Yet another Sig Something Extra Build

I'm in the process of repairing the gear mount in my SSE right now. I too use tri-stock to reinforce the mount plate. While that does strengthen the bottom of the fuse, the weak point is the sides of the fuse. Since the sides and doublers are all balsa, the force from a rough landing results in the twisting of the plate against the sides of the fuse. What is really needed is some kind of lite-ply doubler to reinforce the balsa fuse sides.
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Old 03-22-2008, 03:29 PM
  #167  
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Default RE: Yet another Sig Something Extra Build

I had a similar situation on my Four-Star 40, which had a similar LG reinforcement setup. I substituted a piece of pine triangle stock (made it from scrap) in place of the balsa. I never had a LG mount problem after that...

Bob
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Old 03-22-2008, 09:47 PM
  #168  
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Default RE: Yet another Sig Something Extra Build

I have tried to keep the weight down as much as possible, that is a primary consideration with any of the modifications I have done. I Hope that because the fuselage is sheathed, with grain going vertically (like a shear web) should help. I am also adding fairings for the wing to the fuselage sides that will stiffen up the fuselage a little bit, and all of the fuselage will be covered with the carbon fiber veil.
I am going to have to accept the fact that if I rip the gear lose I am going to have to do some repairs. I can see the cooling duct being something that will bear the brunt of the damage it the landing gear takes a hit.

Edit to add:
The hard point for mounting the payloads, might be setup to help secure the landing gear a bit more, I will have to look at that. Still nothing has arrived from TNT yet, I really can't proceed a lot further until I have the gear in hand so I can make it fit into the structure of the duct the way I want it.
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Old 03-22-2008, 09:49 PM
  #169  
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Default RE: Yet another Sig Something Extra Build

I'm just now building a SSE and my buddy saw that there might be a problem in this area as well. He has his own laser cutter and within minutes he designed these braces that I installed after everything was put together to give it some strength. It slides down over the gear mount and glues to the sides. It appears pretty strong. I guess we'll see.

Brett
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Old 03-23-2008, 10:59 AM
  #170  
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Default RE: Yet another Sig Something Extra Build

Looks like you have come up with a perfect solution, the tie in to the side and the F2 former should make a big difference.
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Old 03-24-2008, 05:33 AM
  #171  
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Default RE: Yet another Sig Something Extra Build

Yup! That's exactly what I was referring to.
Now all I need is that laser cutter![sm=bananahead.gif][sm=bananahead.gif]
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Old 03-24-2008, 03:20 PM
  #172  
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Default RE: Yet another Sig Something Extra Build

Yup! That's exactly what I was referring to.
Now all I need is that laser cutter!
You and I both!!!
But then I'd actually have to learn to use CAD software....


My landing gear is on the way, cool, nice people at TNT!

And a solution to my muffler exhaust dilemma may have a J Tec “off the shelf” solution!!! The engine exhaust is a major consideration in the set up and design of the cowl and cooling duct.

I have tried to come up with my own exhaust but to do it in brass could be very heavy, not to mention that I do not know a lot about metal work. More important I want to do this in such a way that if possible someone could do something similar, or get an idea as how to do something on their own builds/designs…

Anyhow that has been a major hold up on any progress being made with the cowl, If I can use something that I can get from J Tec and have an idea of what the dimensions are I can proceed with the cowl layout and actually start gluing and shaping balsa again, even before the muffler gets here.
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Old 03-24-2008, 04:44 PM
  #173  
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Default RE: Yet another Sig Something Extra Build

Sweet!!!

In a matter of minutes J Tec had answered any questions that I had abot the fit to point where I can now proceed with building the cowl. The J Tec JT601 is the solution, I will not have to deal with the "80 gallon water heater" hanging off the side of my nose. Ok, so it is not going to be piped to the rear, not a big deal, would have been nice but perhaps on the next build I'll go through that.
At least I know where I can have something made up if I wanted too! As a matter of fact someone had mentioned them to me before but I did not bother to look thinking it would have been to expensive.
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Old 03-31-2008, 11:00 PM
  #174  
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Default RE: Yet another Sig Something Extra Build

The J’Tec muffler that I ordered arrived this afternoon in the mail. Looks nice bolted onto the engine and really fits my application perfectly. There also pleasant surprise I discovered, I had weighed the stock muffler and it came in at 4 ounces, the J’Tec only weighs 2.8 ounces! I now have a muffler that I can fit inside the cowl and have lost 1.2 oz over the stock setup, what more can you ask for. I have the top framework/baffle for the cowl glued up, hopefully tomorrow I will be able to get the sides and the mounting for the lower half of the cowl down.
I’ll try and post some pictures sometime tomorrow.
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Old 04-01-2008, 09:14 PM
  #175  
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Default RE: Yet another Sig Something Extra Build

You read my mind about wanting to see pictures....

Bob
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