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Building Tips and technical articles. => 1/2 A building. => Topic started by: John Castle on May 28, 2009, 11:23:01 AM
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I had a wing frame left over from a Little Zinger project I was working on and as usual I got side tracked and ended up with something else instead. I wanted something that turned a little quicker and bounced a little better. The motor is a new Surestart from Xenalook in Canada as I needed it to be as light as possible. The tank is a balloon in the wing. I get the impression that with these wings you can either have an offset fin or a generously offset motor but you don't necessarily need both. I guess that I will find out if that is the case or not. CG is set about a 1/2" in front of the spar.(??)
I think I will try it on 35' steel lines this weekend. :)
Thanks,
John
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Looks nice to me!
If it were me I would start with a CG right on the leading edge and take the added weight off the front till you find the best CG.
It will turn better with a little more elevator. Should turn OK but I think you will agree after flying a few tanks that it is on the tame side.
Many will agree that most of the new sure starts will benefit from tightening the ball socket even though new.
The artwork will one day date this plane! I like it!
Robert
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John,
That is really cool! I like it!
Looking forward to the flight report.
Bill
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Looks like fun...Robert's comment about elevator size kinda depends on where the CG ends up--far enough back to make it a little twitchy, and that'll be plenty of elevator. Far enough forward to make it groove nice and stable, and you might want it bigger. Like twice as big. Or more. Fly it and see.
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Flight report:
All in all it went pretty well. For level flight it grooved pretty good. I flew it on 40' Spider Wire lines. Inside loops were about an 6'-8' radius and outside loops were a little more sluggish at about a 10' radius. I have no idea why that would be the case.?? The biggest problem was loosing line tension on overhead maneuvers, maybe that is normal and I am to much of a novice to know.. I think that for next time I will try 35' lines and see if that helps at all.
The new Cox Sure Start Was a joy to use. With the balloon tank it hummed away obediently for five minutes right side up, upside down or inside out until the fuel was empty. BTW my accomplice and chief test pilot for these adventures is my 15 y/o son Ehren who eagerly gives up his video games to go burn some circles. ;D
John
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John,
Congratulations on a successful maiden flight! H^^
Some things to check:
1. Push rod flex.
2. Elevator throw both ways.
3. Hinge freedom both ways.
4. Thrust alignment.
Bill
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Thrust alignment. ??? ??? ???
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He means check for upthrust, it would make insides tighter than outsides.
The surestarts are reliable little engines, just not powerhouses. I bought a bucketful back when they were dumping them for 6 bucks or something; still have several I've never unpackaged. Not bad sport engines at all, especially with the spring starter that eliminates the mild frustration of starting backwards. Steady runners.
But I wouldn't put mine on anything longer than 35' lines. We're talking about the power of a Babe Bee or so.
So where did the red anodized case come from? Pretty sharp looking.
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Also, if both tips are warped the same direction, the loops will usually be tighter in one direction. If 'washed out' (leading edge down, compared to center rib) then outsides will often be tighter than insides. If 'washed in' then the opposite SHOULD hold. HB~>
One other possibility would be a non-symmetrical airfoil, but it would have to be VERY non-symmetrical for a noticeable effect. I have a biplane built from a pair of assymetrical-airfoil wings that loops real well inside and is nearly impossible to get upright again from inverted flight. I should have mounted one wing each direction, but didn't think of that until long after it was done.
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There is a dealer on that big auction site that sells some of these in a lot of colors. I don't think they are anodized but possibly powder coated but more likely painted. They look pretty sharp but I personally wonder how long they will look this nice after having some fuel on them. If they are painted I don't have much hope they will look nice for long in use
Tim Wiltse actually does anodize engines and has some sweet ones. He also makes a rear rotor 049 which uses some of the Cox componants. Much like the RR-1 did.
http://halfa-works.com/ I know these colors will hold up under fuel.
Other examples or Mr. Wiltse's work:
http://hypercoloranodizing.tripod.com/index.html
Notice also that it is the cast casing and not the machined casing we are more familiar with.
John, Thanks for your flight report. I am glad it went as well as it did. I will agree that 35 foot lines will be much better.
I hope your next flights are soon and improved!
Robert
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Getting light on the lines up high is generally an indication that your leadouts are too far back in the wing tip. On a 1/2A move them forward 1/16 at a time until the tension is there everywhere. On a 1/2A, I think both leadouts should come out one hole, as even 1/2 in. separation will cause a yaw one way or the other when you give control.
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...which is why I use over/under leadout guides on most of my planes.
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Have you ever tried putting both lines through one tube? DOC Holliday
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Doc,
That might work on an airplane with external controls, where you can see any line twists inboard of the tip guide.
Bill
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Thats how I had them in the Cheap Thrill. I used a flattened piece of 1/4 aluminum tubing for a leadout guide. I did not make it adjustable because of the elliptical wing tip. I put it in the right place and had the rudder adjustable to be able to make a tweak if needed. That works pretty good, but not as good as adjustable leadouts.
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Both leadouts through the same guide, I'd be a little concerned about line connectors hanging up on one another. Guess you'd have to use unequal LO lengths, with unequal lines to match. Seem like a lot o hassle to me. 1/2" seperation is enough to avoid problems.
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John, I'm noticing the backplate of that engine is black. Do you know if that backplate is the type that is used on the Killer Bee engines? Every Surestart I've witnessed had the grey plastic backplate. I know the one on my Killer Bee has a very large opening for the intake and the short needle as yours. I would imagine this would give considerable power advantages if that is the style. Ken