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Bob Setzer

A-Solution

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Bob,

 

I did not realize the core is balsa, I thought it was made out of pvc bricks linked with a net.

sometimes ago I tried to build the cowling mould using pvc bricks, but it's not as easy as one could think.

when you lay down the bricks on a curved surface they separate creating a lot of empty spaces to fill with micro.

putting the micro in the voids is not that easy: if the micro is too thick it doesn't fill the voids completely because it's not able to go down where the voids are narrow, if it's too fluid it drips somewhere else and at the end the voids are never 100% full.

on the other hand the quantity of micro used is very very big.

again, when you lay down the bricks on a curved surface some voids are created under the bricks also, as the fuselage curvature is smooth and the curvature created by the bricks is not, so you have to put a bed of micro before to put the bricks.

again the quantity of micro is very big.

another problem: the bricks want to be curved in one direction only, now I see that you used small pieces of bricks-net instead of just a big one and put it diagonally, is it the secret to do a good job?.

do you have any idea about the quantity of micro used for the whole fuselage?

and how long did it take to do the job?I guess really a lot....

but it has turned out as a great job!!


Roads? Where we're going we don't need roads. (Dr. Emmett Brown)

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Bob,

 

I did not realize the core is balsa, I thought it was made out of pvc bricks linked with a net.

sometimes ago I tried to build the cowling mould using pvc bricks, but it's not as easy as one could think.

when you lay down the bricks on a curved surface they separate creating a lot of empty spaces to fill with micro.

putting the micro in the voids is not that easy: if the micro is too thick it doesn't fill the voids completely because it's not able to go down where the voids are narrow, if it's too fluid it drips somewhere else and at the end the voids are never 100% full.

on the other hand the quantity of micro used is very very big.

again, when you lay down the bricks on a curved surface some voids are created under the bricks also, as the fuselage curvature is smooth and the curvature created by the bricks is not, so you have to put a bed of micro before to put the bricks.

again the quantity of micro is very big.

another problem: the bricks want to be curved in one direction only, now I see that you used small pieces of bricks-net instead of just a big one and put it diagonally, is it the secret to do a good job?.

do you have any idea about the quantity of micro used for the whole fuselage?

and how long did it take to do the job?I guess really a lot....

but it has turned out as a great job!!

 

Airnico

The balsa I used was a scrim and scored style cut I inch squares.

I cut the material in 4 by 10-inch pieces for the most part. To build the tooling I applied 6 layers of material with 4 additional layer to the flanges, that makes 10 layers on the flanges (this is the way all the tooling has been made). After a small break we installed the balsa by applying about 1/8 inch micro to the fiberglass and coating the back of the balsa to wet it out. Once each piece of balsa was installed it was never pull off for repositioning, so care was taken at this point, I would say care was taken through out the process). After the balsa was installed we started back at the beginning of the installed balsa and filled the larger gaps with micro (the balsa took around 2 ½ hours to in stall of the lower fuselage tooling. The whole process took 12 hours with 6 people.

The following day I took some 36-grid sandpaper and sanded off the hi spots, than applied a coat of micro slurry to the balsa surface. I used a mil-fiber mixture to fillet around the balsa edge, than 4 layers of material with additional 6 layers on the flanges. That makes a total of 20 layers of material on the flanges, around .26 inches of thickness. This process took 8 additional hours with 5 people.

So it took 20 hours to build the lower fuselage tooling (just over 100 man hours).

11.5 gallons of MGS resin and hardener.

Just the fuselage tooling alone there is around 30 gallons of resin and harder, 300 square yards of fiberglass cloth and 5-6 pounds of micro. Also 2.5 gallons of tooling surface coat.

To this point I have built the Canopy Frame Tooling, Spar Tooling, Speed Brake Tooling, Front Hatch Tooling, Canard Cover Tooling and Fuselage Tooling. Also I have built a really neat 4 axes CNC hot-wire

Cutting machine to cut my Canard and wing cores. I’ve got the canard and elevator down, but have not had time for the wings. I guess that I have to many things going on, what can I say.

The secret to laying the balsa in my case is to cut the balsa to a size that can be applied without trapping air, also I played with the mirco mixture before I got everyone together so as to have everyone mix micro at the same ratio. It worked out really well.

 

Bob Setzer

A-Solution

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impressive numbers.....a huge work!

what kind of glass cloth did you use?

Airnico

The E-Glass fabric is a #7500, a 9.66 oz. per sq. yd., .014 thickness.It is a heavy weight boat or tooling cloth. Plain Weave. Thread Count 16 x 14. Breaking Strength 450 x 410 lb./in. Finished Weight 9.40 oz. per sq. yd.

How things going on your project.

 

Bob Setzer

A-Solution

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Bob,

 

my plug is now complete and I'm going to build the fuselage's molds, a first attempt was made with the lower cowling to test my skills using pvc foam bricks/scrim(do not know the right english word for it) that I did not use before: first impact with it was not so smooth but now I have learned the lesson and think to be able to do a good job.

the only problem is the size of the work: I realized that a one person only cannot accomplish such a big work because it's simply huge.

I do not have any friends who can help me so I have to go a different way, I'm studying a possible solution....

unfortunately I live so far from where all the magic(in terms of aircraft building) happens....

please send me your address by PM, I'll send you some pics.


Roads? Where we're going we don't need roads. (Dr. Emmett Brown)

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Bob,

 

Will you be taking orders to sell the completed parts?

 

Keith

Thanks For showing Interest.

For Now I’m trying to keep the thread educational, for what it’s worth.

With the Holidays out of the way we are going back at it. Here in Florida the weather has been a problem, high in the 40’s with a low of 27 tonight.

To bring you up to speeds on what is going on I am making a heat box to heat cure the tooling to the 200-degree range. I’m hoping to have a Fuselage by Sun-n-Fun. I have a hangar here at Lakeland.

I’ve been working with an engineering firm to see what it is going to take to make an autoclave to make the spar in. It might be over the top but I’d like to build it that way. We will see.

We have been working on the hot wire cnc files for the wing and canard, I’m getting ready to start on a canard. I’ve got the jig table ready to build a set of wings.

If I have said this before Floor space is becoming scariest.

For how this is not a full time project, and in these time you have to be careful for what you wish for.

 

All the best to all.

Bob Setzer

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Nice. But I really worry about post-curing with balsa in there. 200 degrees Farenheit (110°C ?) is quite a lot. The Tg of MGS is somewhere up there, and you don't need to raise the post-curing themperature to or even above the glass transition temperature. Heating to 20°C (40F) below ultimate Tg for 5-8 hours or so is sufficient, there's no need to heat it up that much.

Are you going to try this out on one of the smaller molds first? I'd hate to see the bigger ones ruined since the balsa started to outgas or something.

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Nice. But I really worry about post-curing with balsa in there. 200 degrees Farenheit (110°C ?) is quite a lot. The Tg of MGS is somewhere up there, and you don't need to raise the post-curing themperature to or even above the glass transition temperature. Heating to 20°C (40F) below ultimate Tg for 5-8 hours or so is sufficient, there's no need to heat it up that much.

Are you going to try this out on one of the smaller molds first? I'd hate to see the bigger ones ruined since the balsa started to outgas or something.

 

Your right about the balsa being a possible problem. After talking With the Rep from the Mfg. of the tooling surface coat, he expressed the concern with bringing the tooling to a temp above the boiling point of water. Wood by nature has water content I’ll be honest did not thing of that.

With post curing the parts at !60-170 degrees (which will fall in the 40 degree range) it was recommended that I bring the tooling to a temp close to the tg of the resin one time.

I have taken the three smaller pieces of tooling to 200 degrees over a six hour period, just over 2 hours of that time was at 200. These pieces were built with the same lay-up schedule as the main tooling. All is well for how with these pieces.

Thanks for the input.

 

Bob Setzer

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