Midwest Slope Challenge (WOW) ODR One Design Racer

[Red]

I talked briefly with Erik today. Sounds like the ODR wings do need to be one of those specific airfoils. The event is pretty relaxed and made as fun as possible. As an FYI there’s an airfoil template for spot checking the shape and thickness of competitor planes that was misplaced for awhile, but was found last year. I still haven’t seen the template brought out but JJ, I hear that your plane will be checked next year for sure.

Ty, would it be possible to get a copy or drawing of that template? I'd hate to come all that way and find I did something wrong. I can laser cut. water jet and CNC, so I'd be up to making some to share if its beneficial at all.

 

[TyFlies]

I was afraid I was opening a can of worms mentioning the mystery spot-check template that hasn't been used in years. Let me see. If you've made the best efforts to match the design parameters you'll be able to race, and you're plane will be welcome. And if by some chance it's not, you and your friend can have the pick of my ODR's to race with.
Will send you a PM.

 

[Wayne]

Don't worry - We are not looking at cheating, just like a bit of verbal diarrhea during the conceptual process. We know this is a fun class of racing.

 

[G-man]

I like the Magnum Models COBRA RACER for ODR.
That plane does much better than most of my others for inland slope soaring when the wind is up.
I think Larry will make you a kit on request.
Ask him in email to know for sure.
Larry Blevins <magnumrcmodels@gmail.com>

 

[Doc J]

I was afraid I was opening a can of worms mentioning the mystery spot-check template that hasn't been used in years. Let me see. If you've made the best efforts to match the design parameters you'll be able to race, and you're plane will be welcome. And if by some chance it's not, you and your friend can have the pick of my ODR's to race with.
Will send you a PM.

Love this idea.

Aerofoil checking Template:
But, Ty, if people are saying that with foam wings its not possible to get an accurate aerofoil, (Actually it is possible but fiddly) then there is little or no point in an aerofoil checker.

Quick aerofoil question:
Do you know why there are 'allowable' aerofoils?
Surely it doesn't matter what aerofoil is used, as given a bit of camber and not symmetrical by far the most influential criterion would be the thickness only. In practical terms at such tiny chords and ultra low Reynolds numbers, there would be little if any difference in performance between a Clark Y and an S6060 etc, etc. As with a lot of aerfoil myths with our toy aeroplanes, the use of "special" ".mod", or "proprietary" aerofils is to the largest extent bool sheet.

Wing planform:
It might be an idea to be a little careful with swept forward wings as the race depends on relatively suddenly initiated split-harse turns. The wingtips out in front of the rest of the wing when starting a really hard turn could be a problem. The smallest ripple in the boundary layer would propagate really fast and tear away. There would be no partial or gradual stall. The entire wing would just let go and the resulting flick would probably be irrecoverable - i.e. Dangerous.

Cheers,

Doc.

 

[TyFlies]

G-man: Hi Dave. Sure hope you can come to a Kansas event again soon. It was your magazine articles and great photos that got me there. Have only been going 8 years or so to the slope challenge and the newer fall fun fly, so probably right after your regular trips there. But sloping there Wilson is my favorite type of RC flying by far.
Thank you for all you do for the slope hobby!!

 

[TyFlies]

Doc, I have no idea about aerofoil accuracy of foam. You guys know way more about that than I do. My understanding is that the occasional spot check with the template has more to do with measuring thickness. I believe at mid-wing, but not sure.
I just mentioned the template since this is a public forum and it is a contest. I need to stay out of the aerofoil discussion, I just don’t have the knowledge. At the Midwest event it’s casual and fun, and a high level of trust among the racers.
For what it’s worth most of the ODR’s are balsa sheeted foam rather than something like laminated EPP. Larry’s Cobra cores look pretty precision cut to me : )

I am looking forward to what Red comes up with for sure!

 

[Doc J]

Doc, I have no idea about aerofoil accuracy of foam. You guys know way more about that than I do. My understanding is that the occasional spot check with the template has more to do with measuring thickness. I believe at mid-wing, but not sure.
I just mentioned the template since this is a public forum and it is a contest. I need to stay out of the aerofoil discussion, I just don’t have the knowledge. At the Midwest event it’s casual and fun, and a high level of trust among the racers.
For what it’s worth most of the ODR’s are balsa sheeted foam rather than something like laminated EPP. Larry’s Cobra cores look pretty precision cut to me : )

I am looking forward to what Red comes up with for sure!

Hey Ty, Gotcha.

I'm sure Red will come up with something paractical and fast!

I love MOM racing!

Cheers,

Doc

 

[Wayne]

I like the Magnum Models COBRA RACER for ODR.
That plane does much better than most of my others for inland slope soaring when the wind is up.
I think Larry will make you a kit on request.
Ask him in email to know for sure.
Larry Blevins <magnumrcmodels@gmail.com>

Larry puts out very nice kits! Well worth the wait. He puts a lot of work into them, especially with the pre-shaped fuselage option.

 

[thenated0g]

My very first slope plane was his F-5. Still have it.

 

[JJ Colorado]

My Cobra flies well, but think the new model with the fiberglass fuse will likely be a little slipperier than the gooped EPP fuse of the Cobra.

I'd love to have wing checking at the next WOW contest. As I understand it the main concern is the wing thickness. Easy to make a GO/NOGO gauge for 9.5% of 7" (root) and 9.5% of 5" at the tips. Or just use a set of digital calipers. I'd also like to make sure the root and tip are measured for 7" and 5". I could imagine some folks having smaller wing areas than spec. Of course it would be nice to have a tolerance factor, but that could simply be up to the CD.

In any case, it is a fun event and I hope everyone respects the spec. There also is a spec on the length of the fuse and cross section area of it (no pencil fuselages), as well as weights. In addition to the benefit of keeping the race fair, the spec makes for a plane that is an all around fun slope plane to fly, not just a race only plane. Without ballast my Cobra has a 10 oz per square foot wing loading, and just under 13oz/ft at max weight.

While my Cobra as the A style layout, my new plane is using the B layout. We'll just have to see which flies better. If the new plane is noticeably quicker I'm going to call it the Mamba.

 

[JJ Colorado]

The specifcation regarding airfoils and checking them is clear. Pay close attention to the section in Bold.

Airfoil: Minimum thickness: 9.5%
Allowable sections:
* SD6060 (nominal 10.37% thick) thinned to no less than 9.5%.
* S6061, S6062 or S6063; thickened to no less than 9.5%
* Note: at 9.5% or more, these airfoils are all very similar. If you care to quibble about the relative camber of A vs. B, you’re taking this entirely too seriously!
Competitors are advised to validate their wing thickness before the event (see the first paragraph). Thickness will be verified by template at the contest.

 

[Wayne]

I laugh every time someone brings the airfoils and wing thickness in this thread now. I know I was one of them..

It is a race for fun.

 

[JJ Colorado]

Yep!

I also like that they are 4 plane races rather than one on one. It makes the first turn or two a lot more interesting. Need to mind the traffic while also flying a good line. Not much advantage to turning tighter than the plane right behind you, especially if you are not on the inside line.

 

[Doc J]

I laugh every time someone brings the airfoils and wing thickness in this thread now. I know I was one of them..

It is a race for fun.

Not only in this thread, Wayne.

Rant begins:

The amount of hype about model sailplane (especially, but powered too) aerfoils is simply unbelievable, and for the most part its promulgated by armchair "scientists" who know not what they say, not yet what they do.

I used to laugh hysterically when I read some of the stuff. Now I just shake my head. Do you know there are actually people who make money from concocting computer generated/tested (the most unreliable way) "proprietary" model aircraft aerofoils?

Hard to believe but true.

Its should be FUN FUN FUN always - who needs the aerofoil police?

Yaaahhh

Rant ends.

Doc

 

[JJ Colorado]

Example ODR planes. My Cobra (the wings are actually bright Fluro Orange) and my new plane which I'll call the Voodoo Child as I believe the fuse is one of Eric's Voodoo's.

 

[TyFlies]

It does look fast, and Voodoo Child is a great name but I ain’t skeered. The turns…. : )
It’s gonna be great.

 

[JJ Colorado]

Well, I hope it's fast. The Cobra still flies well but I like the shorter nose and longer tail on the Voodoo Child. Kept the surface sizes about the same so hoping that will provide a bit more stability in the turns.

But it's all about the flying. Looking forward to WOW '24.

 

[JJ Colorado]

Maidened the Voodoo Child today. No trim needed and flies very well. CG 76mm, wt 740g / 26oz.
Only had relatively light winds 5-7mph to fly in but no bad habits so far, though I wasn't pushing it either.

 

[Hill Hobbit]

I used to fly a model in UK MoM races back in the early 80’s called a Plus 3. Designed by Dave Worrall, it was a do everything plane that I literally flew to death! The Cobra looks like its brother from another Mother.