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Old Oct 13, 2012, 03:52 PM
I don't like your altitude
Stupot46's Avatar
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Thanks for the input Richard.I have no idea how these things will stand up under load,hopefully this trial will give an indication.So,better safe than sorry,balsa dowels it is.
Regards Stuart.
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Old Oct 14, 2012, 06:35 AM
I don't like your altitude
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bench swinging (0 min 44 sec)

Couldn't resist
Stuart
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Last edited by Stupot46; Oct 14, 2012 at 06:42 AM.
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Old Oct 14, 2012, 08:08 AM
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Looking good Stuart , can't be many obstacles in the way of constructing the wings now that you've a functioning mechanism. On another of your posts you mentioned a method of locking your wings on, how about using the peg and cam parts that are used in flatpack kitchen carcasses? Should be able to arrange the peg into the wing structure with the cam fitted into the root, these parts would certainly be strong enough and cheap too! Strips of wing-seat foam on the root/butt rib would act as a spring to maintain tension on the fittings.

Trev
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Old Oct 14, 2012, 08:37 AM
I don't like your altitude
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Hi Trev,yeah,it's coming along.I've just been cutting some worktop up to make a press.A pair of sacrificial foam wing roots next to try out the glassing,which I haven't tried before.
Re the wing retention thing,it's just an idea I had,not really relevant here.I'm going to stay with the blade in a box,easier to fit into the roots.I must admit I've thought about the cam locks,but never come across anyone using them.They would need hardware to fit them into the structure,whereas the twist lock idea,if workable,utilises the existing tube in tube set up.
Regards Stuart
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Old Oct 14, 2012, 09:38 AM
I don't like your altitude
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Worktop press and trial roots.I have at least another four bigger clamps,that should be enough.To check I've got the pressure even I'm going to use a sliding bevel;I don't want to make a fixed depth stop as I have no idea how much pressure the foam will take...
Next is cut a trial channel through these and fill it with expanding foam.Also a few balsa dowels to aid the adhesion.
Stuart
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Old Oct 14, 2012, 10:06 AM
I don't like your altitude
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Looking at Kents test rig for the carbon tube reminded me that this thing will need something to test it.
Utilising those two turntables I had for the earlier set ups.Mount them on a couple of pieces of 40mm waste pipe so they can move out of horizontal,and also rotate to follow the sweep.I'll need to extend the steel blades out to an approximate MAC and mount to the disc so they can't tip when load is applied.Which raises the question of how to quantify said loading for a specific wing area?
Regards Stuart
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Old Oct 14, 2012, 11:24 AM
less is more
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United States, CA, Marina
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Quote:
Originally Posted by Stupot46 View Post
.A pair of sacrificial foam wing roots next to try out the glassing,which I haven't tried before.
Regards Stuart
For the sake of simplicity, I'd skin the foam wings with balsa and Gorilla Glue. It's easy, sandable and strong enough for a prototype.

Kent
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Old Oct 16, 2012, 02:54 AM
I don't like your altitude
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Last piece of the puzzle that is the drive train.This came all the way from the good ol'USofA and cost $5 and change including postage! Well engineered and lighter than the previous monstrosity.
Kent,I bought some Gorilla glue(a reptilian cousin Alligator glue)but I need to try glassing anyway so this trial is a good opportunity.

This is how I intend to proceed-
Wrap the perimeter of the roots with packing tape to stop any squeezed out epoxy sticking.
Weigh the two heavier cloth pieces and mix an equivalent weight of epoxy.
Wax paper on the bottom clamping plate,position the roots and wet out the surface.
Place the first layer of cloth,brushing it well down onto the foam.
More epoxy,making sure the weave is filled.
Second layer,repeat as above.
Remove excess with a card,cover with waxed paper and the top clamp plate.
Eight clamps,tightened in turn as you would wheel nuts,check measurements.
Leave over night.
Open the press,take off the paper.Stand back either in horror or amazement!
Can I add the top layer straight onto this,or does it need a sanded key?
Despite Richards doubts I'm going to add powdered graphite to the top layer,in an attempt to get a low friction surface.
So,mix up epoxy,add the recommended 10% by weight of the powder and proceed as before.
Place waxed Mylar sheet and press.
Will that do the trick?
Regards Stuart.
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Old Oct 16, 2012, 07:34 AM
Herk
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Joined Jun 2007
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Stuart, You may have better waxed paper than we do.

Mine tends to stick when I use it as a release agent. If yours is like ours, I recommend waxing the contact side of the paper with additional release material.
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Old Oct 16, 2012, 10:15 AM
I don't like your altitude
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Thanks Herks,will do.
Stuart
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Old Oct 16, 2012, 10:56 AM
less is more
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Quote:
Originally Posted by Stupot46 View Post
Despite Richards doubts I'm going to add powdered graphite to the top layer,in an attempt to get a low friction surface.
You're hoping for a low friction surface by using graphite powder? I would think that the surface will be 100% dictated by the mylar surface that is used as the press. I once sprayed flat black paint on a waxed mylar and layed up a wing. That yielded a glossy black wing. Indeed, exactly the same gloss as the mylar.

Be sure to give us a Mini-How-To for the wing lay up procedure. If you use epoxy as the resin you'll have lots of working time to wipe your hands (gloves) and snap a photo. Your Mini-How-To might encourage others to try this method.

Kent
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Old Oct 16, 2012, 11:07 AM
I don't like your altitude
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Graphite Powder - 200g

Pack Size
Your Price £3.95 ex. VAT
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Product Description
Graphite powder (carbon powder) is odourless filler powder than can be used to add a natural looking grey/black colour to cast polymer products.
When mixed with casting and laminating resins, graphite powder also adds a smooth, hard wearing, low friction property to castings, components and laminates along with a degree of electrical conductivity and thermal conductivity.
This is the stuff.iPad won't let me edit the blurb out
Stuart














Guidelines for Use
It is recommended that the powder is mixed thoroughly with Part ‘A’ of polyurethane casting resins (like our Fast Cast) before adding part B. Never count the weight of the filler powder in the mix ratio.
Compatibility
Graphite powder can be added to most resin systems (including epoxy and polyurethane) up to a maximum percentage of approximately 10% by weight. Doing so will create a very dark, shiny grey colour.
Safety
This product is made up of particles that are incredibly small and will become airborne when the material is scooped, moved or mixed. Always wear protective gloves and a dust mask when handling this product in its raw state.
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Our Graphite Powder is sold by weight and is available in 200g, 480g (1l) and 2.4kg (5l) pack sizes. Please choose the pack size you require from the drop-down menu at the top of the page.
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Old Oct 16, 2012, 11:44 AM
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Stuart, please take care with this product! As one who has used this and other micro powders and very fine fillers with resins in an aviation repair environment , I can assure you that inhaling the powder will make you very uncomfortable! Basic dust mask is the minimum protection. If possible use extraction to draw any airborne particles away from you and out to atmosphere,even a desk fan through an open window , spoon powder into resin carefully and fold in slowly .

Trev
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Old Oct 16, 2012, 01:08 PM
I don't like your altitude
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Originally Posted by Crozzie View Post
Stuart, please take care with this product! As one who has used this and other micro powders and very fine fillers with resins in an aviation repair environment , I can assure you that inhaling the powder will make you very uncomfortable! Basic dust mask is the minimum protection. If possible use extraction to draw any airborne particles away from you and out to atmosphere,even a desk fan through an open window , spoon powder into resin carefully and fold in slowly .

Trev
Thanks for the heads up Trev.I've got a good quality mask,a vac I've rigged so it blows out the window,so every precaution taken.Just hope it does what it says on the tin.
I came across some thin ptfe sheet today,going to try cutting a disc out of it to see how it performs.
Stuart.
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Old Oct 16, 2012, 01:34 PM
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Yes, ptfe sheet is what I would use in the same situation, cuts easily
while thinking about your release wax paper mentioned in post #413, have you thought about using the film sold by Balsa Cabin for plan protection? nothing sticks to it, it's very thin , and...cheap!
Trev
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