On Thu, 7 Aug 2008 09:23:50 -0400, "Morgans" wrote in :
Agreed.
There is a qualified chemist who used to post here. I don't know whether he will see and answer your question.
The "best" epoxies probably cost a great deal more than whatever you can find in a hardware store or your local hobby shop.
Ah--maybe the man I'm thinking of is Gray Fowler, and maybe I've seen his stuff on the pattern mailing list rather than here ... But we have had some rocket scientists here, too, from time to time.
That is the great thing about the GWS Slow Stick, you can have it both ways. A tiny little brushed motor can lift great weight because the motor is geared down to push a large prop, the 505 square inch wing area is shaped somewhat like a parachute so it has enormous lift on a tiny little
400 motor. Because of this it is quite easy to add a pound of reinforcements and still fly very well. Also tiny motors only need cheap batteries. Plus if worst comes to worst, replacing everything that can break only costs $21.00.
I ended up using Elmer's carpenter's glue because that is what someone at the club with a similar problem used. I used the kind that is almost like their white glue.
On Fri, 08 Aug 2008 09:38:37 +0100, The Natural Philosopher wrote in :
I've never found the rocket scientists boring. YMMV. :o)
Yup. That about sums it up.
It's amazing and fascinating to me to get a little peek into the world of materials science. Glue technology is astonishing. It's a great time to have something broken in need of fixing. We've come a long way from Ambroid.
"Martin X. Moleski, SJ" wrote in message news:oeGdnQf3Wu0m8wHVnZ2dnUVZ snipped-for-privacy@supernews.com...
I haven't flown with it yet, but, to make sure that it was air worthy, I applied a lot of pressure trying to break it. I tried to apply at least the maximum pressure that would be applied when flying. The Elmer's held firm, although some of the epoxy that holds the struts on cracked.
I did initially tried taping it with Mylar packing tape. This prevented the Elmer's from drying. Then I pealed off one side of the packing tape, and set it up between two blocks of wood and put some weight in the middle to help clamp the crack seam together. When that dried I did the same thing to the other side. After that dried, I did my stress test. I will put the packing tape back on the top side because this bonds firmly to the glossy surface. I will either put packing tape on the bottom, or glue some 1.5 oz per square yard glass cloth over the crack. I will do this two inches wide, and for the length of the crack, just like my extra-wide packing tape.
Bottom line is that it look like Elmer's glue will hold very well if properly applied. The next time that I will do this I will use regular 3/4 inch strips of tape across several points of the damaged area to keep the crack seam tight until the glue dries. Those portions with the tape will not dry, so I will peal them off later and fill in the cracks with more Elmer's.
I think that I may test attaching the struts to another wing using caulk. I will use the non water based kind. If it bonds very well to the foam, I think it will prove better than epoxy because it is flexible, it will bend without cracking. I am also going to buy some more full length struts so that I can have full length struts on both sides of my new wing.
The GWS Slow Stick can be greatly reinforced without reducing its flying characteristics because it was designed to fly very well even with a lot of extra weight. Many people fly these with cameras, including movie cameras. Even though it only costs $21.00 to replace everything that breaks, I still want to further reduce this cost.
Basically, yes. I tried to get the cheaper fiber glass struts, but, could only find the more expensive carbon fiber. I will put the carbon fiber on the longer trailing edge, and the fiber glass on the leading edge. I am guessing that I can cut the carbon fiber with a hacksaw.
Really fine blade. Just built a new Slow Stick myself. I see they keep changing it. The plastic insert for the center of the wing is new and I don't get the need for that other than you have to use it with the new wing or end up with a wing that looks like V. I have never had a failure of the taped joint of any Slow Stick and I have destroyed more than half a dozen of em over the past few years. Combat with Slow Sticks is neato. I don't like the pushrods they use now either. They make it very tail heavy and I've never had a failure with the smaller diameter rods. In fact, I am using a set of pushrods that are now on their third plane. Using the rods that came with this plane, I would have had to have the batt jammed against the back of the motor and the wing nearly a foot back from the front of the stick. This Slow Stick will be a dedicated platform for a FlyCamOne2.
I wanted to use heavy pushrods, and Hitec HS-81 Micro servos, it flies very well at about two pounds using the original stock 400 motor, and 8 (9.6 volt) 2/3 A Kan NiMH (6 ounces). I do have to have the battery pack about 1/2 inch from the prop, and the engine mount has been extended two inches longer. The wing is in a normal position about six inches back from the motor.
Guess those rods work well with a heavy batt pack. I use a 2S2100mAh LiPo on one Slow Stick and might use a 3S1320mAh on the new one, esp. if I go to brushless. Both SSs are using the 350 D geared with an 1180 GWS prop. HS55 servos and 4 channel GWS rxs. I think you get more bang for your buck with Slow Sticks than with about any other ARF.
Yes, and you can replace the whole thing (everything that is likely to break) for $21.00. I read that a guy used an 11.2 volt LiPoly and and 1147 prop to achieve straight vertical climbs with the stock 400 brushed motor. That may be a little hard on the motor, though.
I am running 400 D geared with an 1147, I was running 1060, but it broke and could not be immediately replaced with a stock GWS prop. I have not flown again since my first ever solo last Wednesday. I expect the 1147 to perform very well. I want to go with a stock GWS prop at least until I can get a good prop saver. Props are cheaper than gearboxes, so I want to go with a prop that breaks much more easily than the gearbox. I have some brushless motors coming from China, $15.00 each including the ESC.
I've bought some prop savers from Lazertoyz and ..now...my inventory of unbroken props is the largest its been in a long while. The ones I bought have two sides for different styles of props. Cheap, too. Much cheaper than the cost of the props themselves and the time spent putting new ones on.
I bought a bunch of -O- rings from them, too. Way cheaper than the local hardware store. I did drill out the center of my props AND I cut the end off of the motor shaft..... to allow for more "give" when I come in hard. Rich
Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:
Since you stated it was a clean break, I suggest also imbedding a couple or 3 toothpicks in each side of the break prior to gluing and taping for additional strength. If the wing thickness allows, I like the round toothpicks.
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