stunthanger.com
Design => Stunt design => Topic started by: Neil Roshier on June 11, 2014, 06:20:54 AM
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I only found the outerzone list of plans last week and have spent days going through them, especially the non-english-speaking-country designs. One design I found was the 'Astro' by Franco Ballesio from Modellistica which you can find here: http://outerzone.co.uk/plan_details.asp?ID=3665
I've often wondered about the tip flow issues, but just assumed the Re would be too low to make it much of an issue. However a forward sweep would reverse the span-wise flow. So would the forward sweep of this design have much effect?
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Search this site for "sweep" -- there's lots of discussion about the ideal amount of wing sweep, and flap sweep, and why.
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One year in the 70's Mike Stott flew a semi scale Hansa jet forward swept stunt ship at the Nats. I recall it flew well.
I don't know if it was ever published.
Dave
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I'll never be one to pick on someon's design. H^^
Does look like it did a figure "9" though.
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thanks for the replies.
Tim I did a search but found some threads that were more about chest beating than the subject at hand, hence my post.
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You have to kind of close your eyes to the chest-beating, and pay attention to who's saying what.
The consensus, such as it is, seems to be that a swept flap hinge line -- fore or aft -- makes for worse performance in the wind. Ditto untapered wings. The combination of tapered wings and straight flap hinge line makes for the wings we see.
The unswept hinge line notion is not universal -- you'll see some good fliers who insist that it's no problem, or is even beneficial -- but you'll also note that most Nat's winners don't have hugely swept hinge lines.
If you pay attention, you'll notice that there's a lot of chest-beating over why one wants or doesn't want swept this or that -- but the airplanes that actually win contests tend to have some mighty similar features.
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Tim, thanks for the input.
I have noticed a similarity in design trends in the images available online, which tends to dissipate a little when international competition is factored in - hence my interest in a 'foreign' design in the link.
As for 'who says what', I am relatively new to this and in addition am in Australia, so the 'names' are all unknown to me. All the same I like to listen to a diverse range of opinions as well, but preferably without the 'wanger waving' one upmanship that sometimes occurs.
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If I name names I'll just hurt feelings. I look at whose one at the Worlds and at the US Nationals, and if I can tell who's top dog in their country if it's outside of the US. I look at the people who's statements seem to be consistent and well thought out across the board, and who don't seem to feel a need to engage in pissing contests. Finally, I tend to give more weight to things said by pilots and engineers in aviation-related specialties, when I know what people do to pay for their modeling supplies.
My day job is a circuit and software engineer for products, and engineering discussions can seem pretty cruel to an outsider (we're critical with each other with reason: mistakes are expensive, and having to justify every detail of your design makes your design better). You can't last long on a design team if you can't distinguish between a perfectly valid and acceptable, if harsh, critique of a potentially bad idea and a personal attack. So I'm probably unusually prone to view discussions that get very critical in a more positive light, as pointing out more issues that need to be considered, rather than as personal attacks.
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A small amount, 1-3 degrees, of forward sweep in the chord line seems to help smooth out transitions in the eights and maybe helps a bit if you get maneuvers pushed a bit too far into the wind. Note, you don't have to sweep the flap hinge line if the flaps have a fairly large root chord. The Beringer's planes a few years ago looked like they used this approach.(You'd have to look at the plans. Photo perspective does funny things).
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Look up "rolling moment due to sideslip" and "yawing moment due to sideslip" . I think you'll see that you're on the right track, but might consider a taller vertical stabilizer.
Reynolds number shouldn't matter.
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The OTS Dmeco Sportwing has swept forward wings, a straight elevator hinge line and a fairly large rudder. One can be made to fly a recognizable OTS pattern. I've copied a couple of articles on swept forward flying wing free flight models. They seem to all have positive tip incidence and very large rudder and sub rudder.
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The dMECO Sportwing was among the designs I'd hoped to attract when I began the VSC back in '89. Jim Thomerson did enter and fly one, which was great to see.
However, with a few notable exceptions (thanks, guys...you know who I mean), OTS appears to have become "the Jamison/Humongous event".
Not at all what we had in mind.
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Aw, c'mon Mike...
There are still those among us not into OTS to "win" a fun, Unofficial and "family-reunion," type event.
Many do, granted, enjoy matching skills to see who flies best on a given day. So?
Unless one or the other is banned, there's room for all. I enjoy seeing both, when I get to a VSC...
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You have to blame the "Jamison/Humongous" craze on the kit manufacturers. They make it easy to produce yet another example. Maybe flyers will get plenty tired of seeing these and branch out into something more interesting?
Floyd