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Old Jan 05, 2007, 10:03 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Another look

Here are the two different types of sides in a little better detail.
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Old Jan 05, 2007, 10:22 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
7,822 Posts
Carbon Fiber

Man... where was this stuff in the '70s? I can't imagine building a model without it. The sides are going to be 1/4" thick when finished, but lots of that will be sanded off. The top and bottom will be 1/4" stuff, too, but the cf will just get bonded to them on the inside surface. It's not that big in diameter. Only 1" at the tip of the tail but only 1 3/4" at the trailing edge. More of that sanding 101 stuff, comin' up... Anyhow, the .007 X .25 strips are just tacked at the ends to keep them in place. The sides are prepared by spreading Gorilla Snot on the short side and wiping the other side with a damp rag, taking care not to dislodge the cf strips. Warm the urethane glue a touch with the heat gun, and remove as much as you can, leaving a thin film. Put the two together under pressure, and wait about 4 hours before checking it.

The Gorilla Snot, or urethane glue, as it's really known, is 100% solids. That means the weight you add will stay there and none of it will evaporate away. It doesn't dry, it cures. It's catalyst is the moisture in the wood. Again, if you live where it's moist most of the time, don't worry about dampening the wood. If you're in the desert like me, you'll wait a LONG time for it if you don't.
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Old Jan 05, 2007, 10:45 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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I'll try to get the bulkheads and keel/tray and ballast box going tomorrow. The fuselage will be built upside down on it's top, and the controls will all be worked out before the bottom stuff is applied. There's triangle stock longerons in the aft fuselage, and the bottom sheeting will be cross grained to help with torsion, a bit. It'll still have carbon bonded lengthwise... There's a little something different in the forward fuselage. The tringular bracing will be there, but the wood grain will go diagonally across the joint, to strengthen it. The ply and bass will be more than strong enough without adding longerons. However the fuselage will get lots of sanding forward, too. That makes that joint thin and week. A piece of triangle stock isn't strong along it's grain, so it will split easily. With the grain diagonally across this 90 degree joint, even if all of it is sanded away, the sides and bottom will still be strongly attached to each other by this diagonal-grained, continuous gusset. It bends easier, too, so it'll follow the bendy bottom coutour.

Gents, as funny as it may sound at the time... don't tell your wife it could be used as a club... for obvious reasons... More of that safety and health stuff, you know...
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Old Jan 05, 2007, 10:51 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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I'll try to get the bulkheads and keel/tray and ballast box going tomorrow. The fuselage will be built upside down on it's top, and the controls will all be worked out before the bottom stuff is applied. There's triangle stock longerons in the aft fuselage, and the bottom sheeting will be cross grained to help with torsion, a bit. It'll still have carbon bonded lengthwise... There's a little something different in the forward fuselage. The tringular bracing will be there, but the wood grain will go diagonally across the joint, to strengthen it. The ply and bass will be more than strong enough without adding longerons. However the fuselage will get lots of sanding forward, too. That makes that joint thin and week. A piece of triangle stock isn't strong along it's grain, so it will split easily. With the grain diagonally across this 90 degree joint, even if all of it is sanded away, the sides and bottom will still be strongly attached to each other by this diagonal-grained, continuous gusset. It bends easier, too, so it'll follow the bendy bottom coutour.

Gents, as funny as it may sound at the time... don't tell your wife it could be used as a club... ... for obvious reasons... More of that safety and health stuff, you know...
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Old Jan 05, 2007, 10:55 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Sorry for the double post... it's Friday... I'm tired...
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Old Jan 06, 2007, 08:28 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Well, I'd post something if I had something worth posting. I worked all day and didn't like what I built so I am starting over on the wing mount / ballast box / servo tray. It's too wide and no one uses standard servos anymore, anyway... just a small setback.
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Old Jan 06, 2007, 09:43 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Grrrr...

I really hate making a post like the last one... ... so I went back out there with my teeth gritted and my sleeves rolled up... my teeth chattered and I rolled the sleeves back down... it was cold. Anyhow I turned on the heater and did some thinking while it warmed up a bit. I narrowed the box formed by the wing mounting plate and the servo / ballast tray. In fact I took 1/4" off each side. Suddenly it was all better. I'll probably cut down the vertical measurement, too...

All in the trial fit mode, here's what it looks like...
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Old Jan 06, 2007, 09:56 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Radio, too

We need to control the model so I like to see that the radio will fit properly. I believe the pull-pull stab is going by the wayside... I want to be able to ballast this one. The wing bolt will go all the way through to the bottom tray, and sheet lead will be cut and balanced for this glider's CG. It'll have a hole that the bolt will pass through to hold it in place, so as not to shift the CG in flight. Several sheets will allow for a more flexible ballast system. Comment on the other Yardbird thread about this please... I've never paid that much attention to ballast, even though I live where the wind blows...
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Old Jan 06, 2007, 10:03 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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About ready for glue...

Awaiting my own final decisions about several little things, like the ballast box and some control stuff...
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Old Jan 07, 2007, 09:25 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Still not happy.

I still don't like my fuselage. I've pretty well scrapped the drawing, and will draw up what I build... like a set of "as builts" if you know what that is... However, while I've been chewing on that, I've not been idle. We were going to fly today... the real one... but it was even too windy for that.

When something's buggin' me like this fuselage, I will generally put it aside and work on something else. Today I did the rest of my tail drawings. The horizontal tail begins as a 10% NACA010 and tapers off to 8% NACA008 at the tip. The planform has changed, however, the rib set can be used for either. Even better, this stab will fit the Houston Hawk. They're about the same size and planform, and my Hawk's still missing a stab, so I'll build 2 and use 1 on the Hawk. I amaze myself sometimes... ... Why didn't I think of that sooner?

Anyhow, here's a little stack of ribs and templates, a day's work, and man, are those tip ribs a pain to cut out accurately! I will be forwarding this stab and ribset to Brian Eberwein at Laserarts to be added to the drawing and short kit. I'll also be sending the same to Mark miller to used for the Hawk.

Then, there's the non-constant taper that I like so well fo rthe fin / rudder...
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Old Jan 07, 2007, 09:32 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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This is turning into...

... a full time job! I have been on the computer and out cutting templates and ribs all day... well, since church anyway... I still need to cut out these fin / rudder templates and check them against the paln I really hate it when something doesn't fit. There's really a lot of work that goes into getting something like this designed and built... What was I thinking???

In reality, I'm enjoying it a great deal... Here's what the tail and templates look like... sort of like my Dragonfly, only better....
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Old Jan 07, 2007, 09:37 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Ideas...

Thinking of thinning the forward fuselage a bit more and changing the inner structure. I'll be at work tomorrow and if I have any urekas, I'll write them down... or scetch them out... At the railroad, we often do our best engineering on napkins...

I hope you're enjoying this... it's sure a lot of work when I could have just ordered one from somewhere...

Jack
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Last edited by schrederman; Jan 08, 2007 at 12:05 AM.
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Old Jan 08, 2007, 12:04 AM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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More on the stabs

On the original drawing, there were no notes on the stab and rudder drawings. The stab diagonals were intended to be optional 1/16 X 1/8 balsa and the leading edge was to be sheeted top and bottom with 1/20 sheet. When the next set of drawings is done, those tails will still be there with the ribs and plenty of notes. I have sent the drawings to both LaserArts and Isthmus Models. Brian may include these ribs in the short kits... but that's his business. It sure beats cutting them out.

If it wasn't so late, I'd go frame up a couple of stabs... gotta work tomorrow, though...

Jack
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Old Jan 08, 2007, 07:53 AM
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Prescott Arizona
Joined Mar 2005
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Jack,
I see that your stab has a tapered spar and yet the leading edge and trailing edge is not. Why do we do that?
Bob
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Old Jan 08, 2007, 06:36 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Bob,

They aren't tapered in width on these, but the thickness does taper. My reason isn't really a reason, but an excuse... it's easier and I'm not that good with AutoCad or Compufoil, so it's a lot of trouble. I can read responses directly on my email at work but can't access this website nor answer. I've been thinking about this all day, couldn't come up with a reason, and finally had to face the bitter truth... I'm lazy...

Jack
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