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Old Jan 08, 2009, 04:53 AM
Nup, I got nothing!.....
evo62's Avatar
Gold Coast, Australia
Joined Jun 2007
2,174 Posts
Yeah, true that!

A bit of medium CA and kicker and it's ready again, only took a few minutes. Now I am kinda glad I went for a EPO foamie instead of the Gentle Lady. I've got nothing against balsa, I just think the ASW is going to have a bit of a hard life getting me over the 'beginner' hump.

Clovus
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Old Jan 08, 2009, 05:17 AM
I'm torquing to you!
Mr Kamikaze's Avatar
Wattle Grove NSW Australia
Joined Nov 2006
7,393 Posts
Quote:
Originally Posted by evo62
Took it out again this morning but found out (the hard way) the EZ connector to the elevator was not quite snug enough. It was tight enough when I moved it by hand but the air pressure must've been a bit stronger then the force I gave it.
Hey Clovus

I just put mine together (3rd plane this week ). It took 1 hour and 20 minutes to put together, switch to 2.4ghz, set up radio and balance. I had to have battery as far forward as possible and add 25gms of lead to get it to balance as recommended. Will be interesting to see how this CG works. Hoping to huck it off the coastal slope tomorrow to see how it glides and performs without power and get it set up for some inland thermal action where that motor will get some work.

BTW mine had the same problem as yours with the elevator connector, sorry to hear about yours but you probably saved me the same fate. I will keep an eye on it throughout the session.

Cheers
Brett
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Old Jan 08, 2009, 12:59 PM
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Brett, Clovus,

Does the manual give a recommended CG (center of gravity) on the ST ASW 28? If so, what do they suggest?

At the fuselage joint of the wing, what is the total width of the wing, front to back?

Where is your present actual CG, on your plane?

Please give more detail, on what is, and where is, the elevator connector problem. For example, are you talking about where the connector slides onto the elevator itself? Or, where the rod, screws into the connector horn? Or? ... How did you fix it? CA glue, or?

Regards.


*************

Steve, thanks.

When you said to make the stabilizer zero with the "middle of the wing", what exactly is the middle of the wing? For example, if my wing is 8" wide, I should look at the middle 4" spot, and the level angle at that point, and match that level area to the stabilizer level? The bottom of my wing, starts out convex, then half way back, levels out a bit, then goes a bit concave in the second half of the wing bottom. Strange.

I have changed the stabilizer on my wild hawk to be less down in front, much closer to zero, and it looks better. I correspondingly will move the battery 1/4" back from the last good flight to start (still 1.5" forward of manf photo suggested spot, which will keep a good CG at 2.7" which represents about 32.5% of the root chord), and will raise the elevator slightly to near flat, for the first test flight. I will further tweak from there based on new flights.

Looking forward to a test flight. I'm glad you discussed this factor. It alerted me to a good flight adjustment dimension, I was overlooking. Thanks. ... First new adjustment test flight will have to wait a while, as presently, its a bit too windy (35 mph gusts, 13 mph ave winds), and snowing.

Regards.
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Old Jan 08, 2009, 01:41 PM
Crikey never leave beer behind
steve wenban's Avatar
Mt Annan Sydney Australia
Joined Dec 2003
23,381 Posts
no problem the centre line of the wing is based on its alignment to the thrust line of an aircraft or the waterline this is the most common aircraft setup .Of course there are always exceptions to the rule with incidence anlges on some aircraft set to allow the performance of that aircraft to react in a known and controlled manner, however about as far as it affects us in the modelling world is the adjustment of the thrust line of the engine to over come torque and pitch problems ,however the wing and tail alignment remains zero zero.
hope thats a little clearer than mud
SteveW
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Old Jan 08, 2009, 03:25 PM
Nup, I got nothing!.....
evo62's Avatar
Gold Coast, Australia
Joined Jun 2007
2,174 Posts
Hiya Cashie,

ST recommend the CoG at 5mm in front of the spar with a 3mm variation.

Wing root is 155mm.

The elevator problem was the screw holding the control rod to the EZ connector was just not quite tight enough. I will try a bit of threadlocker on there once I get it trimmed nicely.

Currently my CoG is at 5mm exactly in front of the spar.

I changed the Rx to my JR 2610 so I only need to carry one Trans with me and to drop the control deflections on the elevator. Windy and raining so can't try it out again.

Clovus
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Old Jan 08, 2009, 07:10 PM
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Joined Jul 2008
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Steve,

It took your nice photo, for me to finally exactly understand zero wing. Now, I can further tweak the stabilizer to optimum. This is a big help in my ongoing search for optimum glider flight. Thanks.


******

Clovus,

at the CG recommended 5mm spot in front of the wing spar, how far is that point, from the front edge of the wing, measured close to the wing joint at the fuselage? ... Thanks.


*********

Foam Repair Options:

I have repaired my 2 planes in nearly every possible way, using CA, 5 min epoxy, and hot glue. Then, I had heard of others using and suggesting white glue.

For $1.25 or so, I bought a 4 oz. bottle of "ELMERS Glue-All" Multi Purpose Glue. Says on bottle, it "bonds strong", "For All Your Needs". "Safe, Nontoxic". "Dries Clear". www.elmers.com

It doesn't mention for foam, but, it works great on my foam planes, even for huge repairs. Can spread heavy or light depending on material. It says to weight or clamp, wait 35 minutes, or wait overnight for full strength. I use tape or rubber bands to lightly hold or clamp it till dry, and I always wait at least overnight, and sometimes a full 24 hours, to allow it to fully dry.

I found hot glue very heavy, can see it (ribs) where you put it, sometimes holds, sometimes maybe not holds so good, dries fast.

5 min epoxy holds great, but its also heavy, can dry a yellowish color, can seem to crack in certain cases, drys fast.

CA dries fast, somewhat clear, but can seem to be brittle, and break loose with a hit in the right angle. Seems on the light side, weight wise.

Elmers white glue, is very inexpensive. It is a very slow dryer compared to the others. Overnight drying is generally a must, and the pieces have to be held in place lightly (so all the glue is not squeezed out with too tight a clamping) with a weight, clamp, tape, or rubber bands until good and dry overnight. It definitely is NOT a fast or instant dryer, like the other three above.

But, Elmers white glue dries amazingly invisible, with no or hardly even a trace of glue residue to see, even if applied somewhat heavy or lumpy. Your repair, most all the time, looks like it was never repaired. The foam re-attaches after glue is dry, as though it was still new, and never broken.

And the fix is strong, and maybe stronger than the others in certain general repairs, in that it doesn't seem brittle delicate, like the others.

I still keep the others around. For example, the 5 min epoxy, seems the best, for a small surface area, but needing lots of strength, such as adding a 1/2" foam extension strip, onto the rudder, for greater plane control. Or, if I am on the field, and I need a quick fix, so I can keep flying, I will use the CA, then, fly 10 - 20 minutes later. If I need a spacer sealer glue, such as between the motor and foam to keep the motor from sliding forward or back in a hard landing, I will use the hot glue.

After using all the others, Elmers white glue is now my first choice for my foam plane repairs. Strong, low cost, invisible when dry, makes repaired foam look new.

I'm not sure the exact type of foam in my plane. I have heard, certain foams, require different type glues. Mine has that round alligator type texture look, if that helps to identify it. The sale advertisement may have said its EPO as I recall, but, someone else said it was different than that. I don't know for sure.

But, whatever type foam my plane has, the Elmers white glue, if one has the time to wait overnight or 24 hours or so for it to dry with a light clamp or tape or a few rubber bands to hold it together til dry, ... works fantastic on my foam plane.

Regards.
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Old Jan 09, 2009, 01:42 AM
Nup, I got nothing!.....
evo62's Avatar
Gold Coast, Australia
Joined Jun 2007
2,174 Posts
Your wish is my command ...

It's 60mm from the front of the wing (at the fuse). Hope this helps bud.
Cheers
Clovus
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Old Jan 09, 2009, 02:35 AM
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Joined Jul 2008
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Thanks Clovus.

At 60 mm from the front edge, and a total 155 mm root chord (wing width at fuselage), that means the CG is at 38.7% of the root chord.

Generally, I have read, the typical standard cg, is at 35% of the root chord. That would be, 155 x .35 = 54.25 mm from the front edge.

I have also seen, a range offered of 25% to 35% for the cg.

One glider owner, a very good one, said he thought optimal cg on his plane glider, was 38%. That is the highest I have ever seen, for a suggest plane.

I found on my plane, the optimal seemed to be around 32.5%, which on the ST ASW 28, the equivalent would be 155 x .325 = 50.375 mm from the front wing edge.

Clovus, if your plane seems to still be porpoising at the 38.7% factory cg, and your stabilizer is at zero angle to the wing, and both sides of the wing look equal in shape and bends, and your stabilizer looks flat with your wing, right to left, when looking at the plane from the front, ... I would try moving your battery forward, to try to get a cg of 35%, instead of the factory spec and current 38.7%.

Fly it at 35%, or 54.25 mm from the front edge, and see if it fly's better.

Then, if it still porpoises, move it to 32.5%, or 50.375 mm back from the front edge. You may have to not only move the battery all the way forward, but might have to add a slight bit of weight, to get the 50.3 mm cg. Fly test it, and see if that helps.

Other alternatives:

1) If it still porpoises at 35%, instead of moving the battery more forward or adding weight, give it a very slight bit of down elevator trim, so you can see the elevator slanting very very slightly down, leaving the cg at 35%, or 54.2 mm.

2) If the jump to 54.2 mm from the front edge seems too much to you, you might try moving it only 3 mm, or to 57 mm, consistent with the manual suggesting the owner can adjust the cg by plus or minus 3 mm to get a better flight.

3) If the front edge of the main wing slants to the rear as it extends toward the wing tip, that needs to be taken into consideration, in calculating CG. The Nasa Center of Gravity Calculator will take that into account.

Looking forward to your flight test results.

Regards.
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Old Jan 09, 2009, 03:17 AM
Nup, I got nothing!.....
evo62's Avatar
Gold Coast, Australia
Joined Jun 2007
2,174 Posts
Cheers for crunching the numbers Cashie. We have a windy weekend forecasted here so may be a while before I get to take it out again. The JR R610M is lighter then the Std Rx so the CoG moved forwards slightly. I'll see how it goes when the wind drops.

Methinks part of the problem was me, overcontrolling it, trying to move it around too much, as Steve pointed out. Guess I have to get used to not trying to fling it around....

Clovus
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Old Jan 09, 2009, 03:34 AM
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Clovus,

When my 55" plane is trimmed pretty close to ok, I can launch it at full throttle (my brushed plane needs full throttle to launch, where your more powerful brushless, may not need full throttle to launch smoothly, -I don't know-), and not touch the controls, and sort of play a game to see how long, I can let the plane go, totally on its own, without touching the controls.

The elevator has to be right to give a very slight climb (even with no up elevator, air over the wings alone can lift the plane if trimmed right), the rudder needs just a very slight touch of turn, so it makes a huge circle in the sky and avoiding distance tall trees, rather than going straight out, into the distance, and out of sight.

And the cg needs to be right so it doesn't porpoise, and so it makes a very slight gentle climb, without porpoising.

I think, sometimes, at my best I have gone 1 or 2 or 3 minutes throwing the plane out on launch, without touching the controls. I.e., it fly's all by itself.

Finally, it will get a little too far way, or need some other adjustment due to wind, or otherwise, and I will have to take control.

But, that is a nice objective to try for. If you have to instantly control the plane after launch, with full throttle, with little or no wind, then, it is likely not trimmed and/or adjusted right. The elevator, cg, rudder, ailerons (I don't have ailerons on my plane) or a combination, of something, is not just right.

Bring it back down, and adjust something, to allow it to fly "by itself", ... longer, smoother, before you have to take the control with the transmitter.

Another method I have read, is to try to fly the plane, using nothing but the trim controls. That will give you a great history of sorts, of what adjustments you need to make, when it gets back on the ground. And it prevents a tendency of over controlling. Of course, if you need to take control immediately to prevent a possible crash, do so, fast. At the same time, try not to over control so much, that the over control causes a crash.

Regards.
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Old Jan 09, 2009, 03:50 AM
Crikey never leave beer behind
steve wenban's Avatar
Mt Annan Sydney Australia
Joined Dec 2003
23,381 Posts
Well Mr K threw his off the hill today and it flew quite well.
ST ASW28 Maiden (4 min 7 sec)

SteveW
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Old Jan 09, 2009, 04:04 AM
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Steve,

Ask Mr. K, what his good flight cg was.

I.e., how far back, from the leading edge of the wing, measured near the fuselage, is the center of gravity that gave him a good flight?

Position of battery, and battery weight and/or size type (factory battery?), and if any weight was added to get his cg.

Also, ask the neutral trim position settings were, for the rudder (perfectly straight?), elevator (perfectly flat zero?), ailerons (perfectly straight flat?), or any other things he did, such as mixing of ailerons & rudder and such (I have never had ailerons, and know nothing about mixing, so any basic "how to" instruction appreciated), that I saw commented on earlier in the thread.

Thanks.

P.S. ... Whew. Wish there was a beautiful windy slope like that near here. Nice weather there. It is 18 F, winter here, and snowing.
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Old Jan 09, 2009, 04:08 AM
Crikey never leave beer behind
steve wenban's Avatar
Mt Annan Sydney Australia
Joined Dec 2003
23,381 Posts
He'll read this for sure and respond him self id say, But CG as I understood it was at the Manufacturers suggested point. Elevator throws where set ay lower rates as suggested and its looked quite smooth in the air .
SteveW
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Old Jan 09, 2009, 04:10 AM
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Sydney
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well done Brett
I will have to get to the slope with you guys one time
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Old Jan 09, 2009, 04:52 AM
Nup, I got nothing!.....
evo62's Avatar
Gold Coast, Australia
Joined Jun 2007
2,174 Posts
Nice Mr K.

Looks like plenty of action going on around you too!

Clovus
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