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Jun 07, 2007, 09:05 PM
Gustavo Exel
gustabmo's Avatar
Quote:
Originally Posted by Richard S
A couple of test flights with the new fin and rudder on an otherwise stock TabooGT has proved that for me the upgrade has given a definate improvement.
Richard,

Great to know about the improvement in launch height! Congratulations!

What do you think is the reason for the improvement? The airfoil, the stiffness or something else?

Gustavo
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Jun 08, 2007, 06:10 PM
Registered User
I think it's the change from what is effectively a flat slab, to a real airfoil.

I'll be flying it in a competition tomorrow so should be able to get a better idea of how much of an improvement it is.
Jun 10, 2007, 09:02 PM
Registered User
Phil,
Could you please comment on your wing lay-up. Is it 1.7 oz. kevlar without doublers? The leading edge is it uni-carbon or woven carbon and what weight? The reinforcement at the bottom of the servo bay, is that done after the pocket is cut? Also the servo bay seems to have a lot of clearance?

Thanks

Tom
Jun 10, 2007, 10:09 PM
Registered User
The LE fabric (the 3/4" wide strip that wraps the LE) is made from a layer of balanced 2.4oz carbon fabric and a layer of 0.8oz Kevlar.

The main skin of the wings is 1.7oz kevlar. There were no doublers except for a narrow strip of 1.4oz glass at the wing center.

The servo bays were cut after the wing was bagged. I cut a large opening in the skin and removed all foam, all the way to the top skin. I then added two layers of the 2.4oz balanced carbon fabric. The fabric was cut on a bias. One piece covered the front and back edges of the servo hole plus the bottom of the hole (the bottom of the hole coincides with the top skin of the wing). The second piece of carbon fabric covered the inboard and outboard edges of the hole as well as the bottom of the hole. So the four edges of the hole got one layer of carbon while the bottom of the hole got two layers of carbon. The hole was made large enough so that a D60 servo with the mounting ears cut off would fit and have a bit of extra room to slide fore and aft a bit as well as a bit of room to slide spanwise in the hole. This was done due to some uncertainty about how easy it would be to make the linkages to the exact correct length and how hard it might be to actually attach them to the servo. The ability to shift the position of the servo in the hole offered some flexibilty when it came time to connect to the flaperon linkages.

Adding two layers of carbon to the bottom of the hole stiffened the skin where the servos would be glued down and also prevented the top skin from being deformed from the correct airfoil shape. The servos were glued down, they were shimmed with balsa shims between the servo and the sides of the servo well, and then balsa sheet was added over the servo and sanded flush to the bottom of the wing. a layer of 1.5oz glass was put over the balsa also. I hope I never need to replace one of those servos
Jun 11, 2007, 01:25 AM
Kevin Botherway

faced alierons


Hi Phil
I also heard at poway that on your own models you were facing the alierons etc while in the vac bag on the first layup if thats so could you explain the method???hope to see you agin next year with lots of other kiwis

kind regards
rowdy
Jun 11, 2007, 09:56 AM
Registered User
Rowdy

I would very much like to see you return to Poway with a large Kiwi team. I was very impressed with your flying at Poway this year and Tankies third place finish last year was also very impressive. You were well into the top five this year until a couple tough rounds in rounds 9 & 10. Your near miraculous save in round nine was the most amazing DLG flying I have ever witnessed. I think team Kiwi will be a major force in any upcoming F3K world champs whether that Joe guy joins your team or not

Prefaced flaperon hinge lines the easy way

I have been doing prefaced integral flaperon hinges on my DLGs for a while now. The method is based on Mark's writeup but I have simplified the method based on my experiences. I have been thinking about doing a writeup on the method for a while so I may as well do at least a short writeup now. The simplified method is listed below:

1) Cut the flaperon loose from the main core. Use a straight edge and a knife blade mounted on a block of wood as in Mark's document.

Simplifications: Don't worry about the exact angle of the cut, it really won't matter. You can work out the ideal angle if you want but just having the blade 90 degrees to the wing bottom will work fine also. You only need to make a single cut to separate the flaperon from the main wimng core, you do not need to make a second cut or remove the little triangular bit of foam from the hinge line.

2) Wrap the flaperon LE and the main wing TE with a strip of 0.8oz Kevlar. Use a wax paper transfer technique to do this. I used a strip of bias cut fabric that was 1/2" (13mm) at the root end and 3/8" (9.5mm) at the tip end. If anyone is interested in more details on how to actually do the wax paper transfer technique to atatch the fabric , just ask.

Simplifications: You don't need to put a piece of precured fiberglass on the edges before wrapping them. The 0.8oz bias Kevlar wrap provides enough torsional stiffness to the flaperon all by itself for a DLG flaperon. You could also use the more common 1.0oz Kevlar for the job. I use the 0.8oz because I have some of it and it handles nicely. I think 1.7oz Kevlar might not work well because it might not handle the tiight corners as well and would make a bigger bump in the layup. Light fiberglass would work well for the wrap but then you would probably want the precured bit of glass on the edge of the flaperon to get adequate torsional stiffness.

3) My simplified procedure uses a simple piece of balsa strip in the flaperon hinge gap during bagging rather than the foam wedge shown on Mark's writeup. The only function of the balsa or the foam wedge is to maintain the proper alignment between the main wing and the flaperon during bagging. You want the aproximate .03" gap between the two surfaces to be maintained so that the hinge operates properly.

Apply a layer of celophane tape (office tape) to both sides of a sheet of 1/32" (0.7mm) balsa. Use a knife and straight edge to cut a narrow strip from this taped balsa sheet. The width of the strip will match the tapered wing thickness at the hinge line. The strip may be slightly too narrow but be sure that it will not be wider than the wing thickness. You don't want the balsa strip to protrude above the foam core surface. Wax the balsa strip with carnauba wax. I just put a blob of wax in a paper towel and then draw the balsa strip through the paper towel while pinching the towel over the strip with the oposite hand. Get lots of wax on all four edges of the balsa strip.

Simplifications: It is far easier to make this balsa strip than it is to cut a perfect foam wedge and then cover the foam wedge with tape. If you think through the required dimensions for a foam wedge, maybe draw a little diagram, you will find that the cross sectional shape required for this piece is not a wedge at all. For modest aileron deflections I found that the the top gap at the aileron tip is the same .03" as the desired gap at the bottom or hinge line side. So the desired shape for the spacer is not wedge shaped, but a simple rectangle shape. At the root end, the top gap came out to maybe .04". At the root end I simply took a small sanding block and very slightly beveled the aft end of the main wing and the front edge of the flaperon to get the extra tiny bit of clearance for up flaperon travel. This was just a tiny bit of sanding and only near the root end. You could also simply widen the entire gap to .04" by using slightly thicker balsa. The big simplification is to realize that you don't need or even want a wedge shaped filler piece and that a simple piece of balsa will do the trick better and easier.

4) Attach the flaperon core to the main wing with a few little strips of light fiberglass. Put the balsa spacer in between the two pieces to maintain the correct spacing. I just use four glass strips about 1/2" wide X 1" long, 0-90 cut.

Simplifications: No simplifications on this step except to point out that the glass strips are attached with 3M77, not epoxy. You simply use a wax paper transfer method to attach the glass strips. Once attached, the glass strips are very secure. You can then operate the hinge and remove the balsa spacer. This allows you to wet out the facings during the bagging process and simpy reinsert the spacer after the wetting out process.

5) While bagging the wing you want to wet out the facings and the litle glass strips. It will be far easier to create the hinge after bagging if you do not leave any excess epoxy in the hinge line area. I used Graham Allen's method of pre bagging the core between paper towel layers to remove all excess epoxy from the hinge facings. This worked very well. With the integral prefaced hinging method you do not want or need excess epoxy in the hinge area. Without the prefacing, I always added an extra strip of epoxy to the main skin layup over the hinge line. Don't do that with the prefaced hinge method. Excess epoxy will just migrate into the hinge area and lock the balsa spacer in place and create a lot of extra work when you go to trim out the hinge area.

6) To trim the hinge after bagging do the following:

A) Score the bottom of the hinge with a straight edge and a triangle file or in place of the file just use a hand held fiber cutoff disc drawn along the straight edge.

B) Cut the root end of the flaperon and open up a gap between the flaperon and the fixed center tab by drawing sandpaper through the cut.

C) Cut the top of the hinge with a knife and straight edge. Make the cut directly in the center of the gap.

D) Open the hinge 180 degrees and pull out the balsa spacer. It should just pull right out if you didn't leave excess epoxy in the hinge area.

E) trim the skin overhang off with small curved scissors.
Jun 11, 2007, 05:14 PM
kak8
Mark S - what a great idea to use the peel ply on the leading edge mylar - thanks for that. I was bagging my first Tabooish`ish wing yesterday. The LE is almost ready out of the bag.

The wax paper transfer works great too - my first time.

I put the antenna wire in my layup - it might be difficult to sand the dihedral now.

I also added some UD carbon over the 1,5mm carbon rods.

But I need another kind of pencil to draw the lines
Jun 12, 2007, 01:56 AM
Thread OP

Prefaced flaperon hinge lines the easy way


Nice one Phil, that is way, way simpler than Dr Drela's method, which I've abandoned as it takes to long. I particularly hate messing with the little foam wedge.

Will you please post some details on the wax paper transfer method that you use to apply the aramid facing's. Can you use the same method to create the wrap around aramid doublers / facing's that you had on your Supra in Slovakia?
Jun 12, 2007, 08:42 AM
Registered User
Quote:
Originally Posted by kak8
....But I need another kind of pencil to draw the lines
There are a couple ways to draw on Kevlar in a way that won't show in the layup:

Use a scratch awl. This is a tool normally used by woodworkers to make scratch lines on wood. This tool when drawn alomng a straight edge will distort the weave slightly in a way that leaves a visible line for cutting but will not show in the layup of the finished wing. This works on 1.7oz kevlar, not for the loosely woven 1.0oz stuff.

Use a fabric pen. These are sold in the fabric section of Walmart or in fabric stores. They make a line with disapearing ink. The line is quite visible for a long enough time to cut the fabric but then the line fades away and disapears.

When using the loosely woven 1.0oz kevlar you should always be using a wax paper transfer method and then you draw on the wax paper with a sharpie marker.
Jun 12, 2007, 09:14 AM
Registered User
Quote:
Originally Posted by markStockton
Will you please post some details on the wax paper transfer method that you use to apply the aramid facing's. Can you use the same method to create the wrap around aramid doublers / facing's that you had on your Supra in Slovakia?
1) Roll out the Kevlar on a smooth bench and get the weave all nicely aligned.
2) Spray a piece of wax paper lightly with 3M77 and then stick this to the Kevlar.
3) Use a straight edge and a fine point sharpie pen (permanent marker) to draw the desired shape on the wax paper.
4) Cut out with Kevlar scissors.
5) Begin peeling off one end of the wax paper from the narrow Kevlar strip. Fold over a little tab of wax paper to act as an easy lift tab for when it comes time to remove the wax paper from the Kevlar.
6) Spray the Kevlar side of this strip with 3M77 and apply it to the wing trailing edge (the aft end of the wing where the hinge line is, the flaperon has been cut off already). I use a medium amount of 3M77 for this, way more than the light mist used to hold the wax paper on but less than I would use for a LE fabric. Hold the wing up to a strong light source while you tack the wax paper backed kevlar strip to the wing aft edge. You can see through the Kevlar to better center the narrow strip on the wing. Now press the strip of Kevlar down to firmly attach it to the wing aft edge by rubbing through the wax paper.
7) Using the little tab of wax paper you previously folded over, lift and peel off the wax paper backing. Use one finger to hold the end of the Kevlar strip down while you peel the wax paper off.
8) use little curved scissors to cut any excess length of the kevlar strip off.
9) Carefully fold over the Kevlar and smooth it down on the top and bottom faces of the foam core.

Applying the Kevlar wraparound facing to the flimsy, floppy flaperon

The flaperon foam core is very flexible and hard to control while applying the Kevlar wraparound strip. I use a balsa stick as a handle to control the flaperon core as shown in this post .

Wraparound doublers

If the flaperon needs a doubler in addition to facing the LE for additional torsional stiffness then the 0.8oz wraparound facing can be wider and shaped to act as a doubler that extends farther onto the face of the flaperon as well. I have not found this to be needed on DLG flaperons that are driven from about 1/3 span from the root end but this link shows the method on a Supra wing tip .

In this case you will be cutting a Kevlar piece that is not just a narrow strip but rather it is a larger shaped piece. You should draw a centerline down the length of the piece using the sharpie pen on the wax paper. This center line is then aligned on the flaperon edge.
Jun 12, 2007, 04:22 PM
kak8
Thanks Phil. I was just googling for the "Fabric pen" but can`t find one with the disapearing ink. There are some that can be removed, brushing some water on it or ironing. Do you know who makes the pens?
Jun 12, 2007, 06:18 PM
Registered User
I bought mine in the fabric department at Walmart. It is a small marker that has a purple tip on one end and the label "disapearing ink" printed on that end of the marker. It has a blue tip on the other end with the words "Mark-B-Gone" written on that end of the marker. I don't have the original package that it came in. It was a hanging item in a plastic blister pack.

The term "fabric pen" is my own term. I don't know what they are correctly called. Maybe "fabric marker" would be better for searching or the "Mark-B-Gone" which apears to be a brand name since it is accompanied by a trademark symbol on the marker. Or just go to the local Walmart and look at the small hanging items in the fabric department.

I should say that I don't use my fabric marker anymore. I found that they don't last very long and am able to do evrything I need with either a pencil or a scratch awl. They might still be good for hobbyist use where you don't need for it to last long.

I just Googled Mark-B-Gone and found this:
http://columbiariverquilting.com/mark_b_gone.html

Now I know what the blue end of the marker is. It is water soluble ink. I don't use that end of the marker.

OK. I found the one I have:
http://www.steinlaufandstoller.com/M...%20Pencils.htm
The 673-60 is the one I have although you don't need the blue end so you would be best off if you found one with just the purple disapearing ink end on the marker.
Jun 13, 2007, 01:43 AM
kak8
Thank you very much. They should make a marker that disapear when you roll epoxy on it
Jun 18, 2007, 01:03 AM
Thread OP

Finally Another Tabooish Born


I have finally finished the Tabooish with the over size Super Gee spar caps. Just in time as we leave for the South African gliding nationals on Friday morning.

It turned out a very respectable 265 grams, I'm very happy with that as this is my windy weather model. It can take up to 120grams ballast!!!

Final point that occurs to me is we havn't discussed CG on this thread. Now this is the second model in a row that I started with the CG as 65mm from the LE at the root and within the first day's flying pulled out 2 grams nose weight. Where do the rest of you CG your TabooGT / Tabooish models?

Ok, so I lied, I'll try and make this my final point. I remeasured my tail moment when assembling this model and it turns out that my Tabooish boom length is 50mm longer than the standard GT. According to observers mine straightens out in a launch much sooner which they believe is contributing to the extra launch height I'm getting over the GT pilots here.
Jun 18, 2007, 01:19 AM
VHO
VHO
glider misguider

A tabooish comes third at Jerilderee


Where the heck is Jerilderee and so what you might ask. Jerilderee is a small town apprx 6 hours from Sydney, 4 hours from Melbourne, 8 hours from Adelaide, 12 hours from Armidale and goodness knows how many from Brisbane. It is the site for the largest open thermal contest in Australia. The thermal contest is organised by LSF Australia, and has been running for 30 years...

BTW, David Hobby won again.

This year they ran HLG just as a sampler to encourage more participants next year. The task was 2 heats of 5 by 3 min max (simultaneous launch, 1 launch per flight) and the final was essentially a round robin last down affair.

There were 7 entrants.

Here you see the finalists showing off their wares. My Tabooish (I'm the old bloke on the right, just under the starters horn) came third. Maybe not the world champs, but you have to start somewhere.

Was beaten by an Aspirin....


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