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Old Dec 17, 2009, 09:16 PM
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TADA!! Wonder how many levels before I need a step ladder.
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Old Dec 18, 2009, 12:04 AM
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mr ray's Avatar
Canada, BC, Kamloops
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Wing and stab angle

Hi John, Here are a couple of pics of my angles. Not parallel. So how do I fix that?..Ray
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Old Dec 18, 2009, 03:19 AM
Stuart
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UK, Cardiff
Joined Dec 2008
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Mr Ray, balsa stcks bend under their own weight, and each one is different.

Prop the gambler upside down on two piles of books, one just forward of the stab, another under the fuse. Put a spirit level on the stab or the flat bottom on the wing and adjust the piles of books till the spirit level indicates level.

If the stab and bottom of the wing are parallel then both should now be level.

Not sure what the relative angles should be, but the plans show the stab TE angles downwards about 1/2 degree relative to the bottom of the wing.
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Old Dec 18, 2009, 04:15 AM
Stuart
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UK, Cardiff
Joined Dec 2008
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Quote:
Originally Posted by John255 View Post
Srnet,
Tape has good strength in sheer direction. I use 1/2" wide electrical tape that has good adhesion, but peels without leaving residue. See pictures below. Notice the carbon tube connects the spar.
John255
I use two layers. The first is applied and then split along the join with a knife. I then use another layer to join the wings. Thus when you remove the tape you dont pull up the covering.

Agreed on filling the core of the carbon tube, the pulltruded carbon tubes do have a tendancy to split, sticking something in the centre does seem to prevent this happening.

I found a supply of steel locating pins recently, I was scrapping some old VHS tapes, and inside are some polished steel pins, 20mm long and 2.5mm in diameter.
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Old Dec 18, 2009, 04:55 AM
Stuart
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UK, Cardiff
Joined Dec 2008
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Quote:
Originally Posted by John255 View Post
Srnet,
OK I can see the hinge. The center section airfoil would have to be flat on bottom. Any curvature would cause the space between the two halves to widen when folded open.

So how is the spar with dihedral angle maintained across the two halves?

This is sometimes done with a bent removable pin. What mechanism do you see for making the wings rigid at correct angle in the center when wings are held together with hinge?
Regards,
John255
Well the bottom of the gambler wing is mostly flat.

Whilst I can see how the kevlar hinge itself would work, I am not so sure about a leyer of tape being enough to keeping the two wing halves together at the right angle.

I have tried removeable tips without joiner rods, just PVC tape does not work, push down on a tip and the PVC tape pulls off easily. Glass strapping tape is a lot better, it does not stretch much, and is just about acceptable. I doubt however it would be good enoung to maintain the wing angle on a DLG.

How you get a joiner rod in when the wing is hinged at the join, I cannot work out.
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Old Dec 18, 2009, 08:34 AM
Gambler-AG DLG Designer
Allan Wright's Avatar
Lee, NH, USA
Joined Jun 2001
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Quote:
Well the weather let up enough that I took my Gambler out and give it a bunch of hand tosses in the snow. It seemed to glide alright so after about 6 or 7 tosses I tried a gentle discus launch. It went up but was upside down. Now I'm thinking this is my fault because I am throwing it wrong. I only tried 3 discus launches and each time it was upside down,I was able to recover and land it safely but by then my hands were numb so I packed it in. I had a surprise when I was walking back to the car, you see it was kinda foggy and my antennae had frozen and would not collapse. The joys of winter gliding. Overall I was happy with the way it flew and was surprised at how sensitive it is to any control. Well guys wadda ya think? Am I throwing it wrong or what? I gotta tell you though it seems like this type of flying is going to be a lotta fun!...Ray
When you launch you actually throw at the horizon. The plane will do all of the climbing itself using the lift from the wing. Also almost ALL new DLG pilots hold on too long, you could be a severe case. Here's what I suggest. Start off without spinning and just do some gentle side-arm launches. Once those are going well add power until you're going full power side-arm, then slow it back down and add the spin. A good side-arm launch is a good component of a full DLG launch.
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Old Dec 18, 2009, 09:26 AM
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Quote:
Originally Posted by srnet View Post
Well the bottom of the gambler wing is mostly flat.
I doubt however it would be good enoung to maintain the wing angle on a DLG.......How you get a joiner rod in when the wing is hinged at the join, I cannot work out.
'
Srnet,
I like the extra layer of tape at the joint idea.

And SS pins from VHS cassettes also a usable source for pins.

No magazine could ever compete with the sharing of knowledge on these threads!!!

The joiner rod in dihedral wing can be a sticky issue. That's why I like built up center joint with ply doublers and straight join rod in the non-launch wing. However, the door is open!!!

Regards,
John255
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Old Dec 18, 2009, 09:39 AM
Gambler-AG DLG Designer
Allan Wright's Avatar
Lee, NH, USA
Joined Jun 2001
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Originally Posted by mr ray View Post
Hi John, Here are a couple of pics of my angles. Not parallel. So how do I fix that?..Ray
Of course if you take that and turn it upside down the sticks bend/flex a different way and give you a different reading.

On to the question of how to fix, it appears that you should be able to correct the angle by adding a wedge under the trailing edge of the wing. I'd trace the outline of the fuselage on the wing, cut away the covering. Make a solid balsa wedge the right size with a hole for the hold-down bolt. Dry fit and adjust until you're happy with it. Once you are, cut out the center of the wedge where it won't be in contact with the fuselage (so it looks like a 'V' sort of. Glue the wedge to the bare wood exposed on the wing. Re-cover the wedge and wing. Fly.

Before you do all this work, fix your launch technique.
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Old Dec 18, 2009, 02:11 PM
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Mr. Ray,

There is a good possibility the advice you're getting on launching up could be the problem, but until we see a video it's speculation. And, we all know HL is probably the only sport where you can throw up all day and not be sick!

I was suspicious of a possible build error in decalage which is also speculation. And, I did assume you would use fairly stiff sticks to check it out. A 36" straight-edge can also be used.

The Gambler drawing shows the TOP of the stab to be in straight line with the BOTTOM of the wing. If built this way the result would be about .5~.75 deg of positive decalage which would be fine. This is because decalage is measured through the center of the air foil, not the bottom.

So you would be little bit off, but you could place a rigid straight-edge on bottom of stab to bottom of wing and eye-ball that the two surfaces are nearly parallel to the straight-edge.

If they are not parallel there are several ways to fix it. The method I like is to shim the wing under the nylon screw until stab and wing surfaces are parallel then make a balsa doubler to glue on the sides of the pod. When glue sets up remove the shims. This and other pod repairs are easier if pod is painted instead of covered with film.

Allan's method sounds real good too, but without a picture I only have a vague idea of he's suggesting.

Good luck, and I do hope to hear more about your frigid soaring.
John255
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Last edited by John255; Dec 18, 2009 at 02:16 PM.
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Old Dec 18, 2009, 02:23 PM
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Shouldn't you be javelin launching the Gambler until trimming is right. DLG adds complexity.
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Old Dec 18, 2009, 02:34 PM
Gambler-AG DLG Designer
Allan Wright's Avatar
Lee, NH, USA
Joined Jun 2001
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What John was trying to say is the datum line of the airfoil on the AG series isn't actually in line with the bottom, even though the bottom of the airfoil appears to be flat. See this photo of the AG25 which is similar to what's used on the Gambler. I didn't have the proper airfoil graphic handy but this one explains what's going on. The angle difference John shows with his red lines over the plan is intentional, to make sure there is a 0-0 incidence between the elevator and the airfoil's datum line.

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Old Dec 18, 2009, 03:42 PM
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What I said was as clear as I could make it and needs no further explanation.

If the Gambler is built as shown on the plan there will be an effective positive incidence between the horizontal stabilizer and the wing. Some may call this positive decalage.

This is common in many glider designs. To have 0-0 effective incidence the stab line would have to go through the data line shown in your drawing.

However, please accept my congratulations in using an image to help make a clear statement in all languages of what you are talking about.

Regards,
John255
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Old Dec 29, 2009, 05:45 PM
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Canada, BC, Kamloops
Joined Dec 2008
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Happy New Year to Everyone

I have a question that I hope someone will answer for me. If you require up elevator all the time your gambler is in the air do you need more weight in the nose or less? I have been fiddling with the weights but can't seem to get it to fly right.....Ray
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Old Dec 29, 2009, 06:16 PM
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Woodstock,Ga.
Joined Jun 2004
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Quote:
Originally Posted by mr ray View Post
I have a question that I hope someone will answer for me. If you require up elevator all the time your gambler is in the air do you need more weight in the nose or less? I have been fiddling with the weights but can't seem to get it to fly right.....Ray
Less!!

One way to think about it is that you are using the up elevator trim, which pushes the tail down, to hold the heavy nose up.

Check out:
http://www.polecataero.com/handlaunchu/cg-location

Buddy
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Old Dec 29, 2009, 06:19 PM
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My Gambler (finished up a couple of months ago) needed noticeable up trim. When I removed a bit of the 3/8 oz. of lead in the nose I was able to remove a bit of the up trim. I have not yet completed the process of checking out and trimming yet because I'm kind of a wimp when it comes to cold weather. Try removing SMALL amounts of nose weight and see what happens. Be ready for your plane to become more sensitive on the sticks as this will also be moving your CG rearward.

The need for up trim in the elevator could also be related to decalage issues that were being discussed earlier in this thread.

I think Buddy Roos is pretty much on with his post (post #2940) on launch technique. I have observed the things he mentioned as I have been trying to learn to launch. I have a few good friends who are proficient at launching who are coaching me. I've never rolled my Gambler all the way to inverted but I have had the wings vertical a number of times. I have found that I get the best lanches by keeping my arm out straight to my side and level with the horizon throughout the launch. The tendency for me is to want to whip my arm forward for more speed just as I am about to release. This whipping thing causes nothing but trouble! When I whip my arm it seems I also twist my wrist inward and also let go too late. This is where the roll comes from. My friends say it's more about technique than it is about brute strength. So far my limited experience seems to support what they say. It kind of amazes me that my highest launches are ones that don't feel like I got a lot of oomph into it.
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