Midwest Slope Challenge (WOW) ODR One Design Racer

[Red]

I think I'd like to design and build one of these. Looks like a fun class, and any kind of racing is right up my alley. So, I have a question about the rules regarding planform as its not quite clear to me. Referencing the drawing, I assume A B & C are legal but what about D & E? I just want to understand so I can design properly. I thought I recall a plane called a Hammer Head that was forward swept like E but I can't be sure.

Thanks!

 

[Hawaii Sloper]

I'd go for E! Love forward swept wings

 

[Red]

I'd go for E! Love forward swept wings

I like it too, I just want to make sure its legal.

 

[iti20090]

I think I'd like to design and build one of these. Looks like a fun class, and any kind of racing is right up my alley. So, I have a question about the rules regarding planform as its not quite clear to me. Referencing the drawing, I assume A B & C are legal but what about D & E? I just want to understand so I can design properly. I thought I recall a plane called a Hammer Head that was forward swept like E but I can't be sure.

Thanks!

I am following D as a big fan of swept wings, right now having chopped and about to sweep back the wing for a bagged home brew made by one of our local chaps.

Cheers
Dave

 

[Wayne]

Sweep it forward.

 

[Red]

Sweep it forward.

Still waiting on a ruling, but that’s how I’m leaning.

 

[TyFlies]

Red, Just saw your post with the question. It's really cool that you're wanting to design one of these racers. i dont know the answer, but I'll direct a couple of guys to this thread who should know.
And of course any of you are more than welcome to fly in Kansas with us!.

 

[Red]

Red, Just saw your post with the question. It's really cool that you're wanting to design one of these racers. i dont know the answer, but I'll direct a couple of guys to this thread who should know.
And of course any of you are more than welcome to fly in Kansas with us!.

Thanks Ty, I appreciate it. I am actually considering coming out with a buddy, so I'd be up for some racing.

 

[Wayne]

Lets wait for the answer, but I have the same memory as you, there was at least one kit with forward sweep long ago. I was eye balling that one back then, but think it was very limited production.

 

[TyFlies]

That's great to hear Red. It's a relaxed group of guys and you'd fit right in. The official dates of the contest are the weekend after Mother's day, so in 2024 it will be
Thursday May 16th to Sunday May 19th. Contest is generally over by Saturday evening. It's usually about half fun flying and half contest flying. Most people stay in either Wilson, KS or Lucas KS. Lake Wilson is between those two towns. There's also a good public campground at the lake.
Also the last few years we've had a fun fly late September / early October.
I've pinged a couple of people and there will probably be a post with an answer to your planform question soon. If not, I'll reach out to someone by phone.

 

[m-dennis]

This is Mark Dennis, I am the CD for the Slope Challenge.
We have no problem with 3D printed fuselages. The rules allow for any construction material for the fuselage.
3D printing wasn't around with the rules were written about 28 years ago, but the ability to get a precision airfoil with 3D printing would be the reason it would not be allowed for wing construction. Laminating balsa or obechi over a foam core or balsa ribs or using strapping tape will never get you a precision airfoil. We don't care what spar system is used, so the wing can be as stiff as you want to make it within the weight limit for the whole plane. Would a 3D printed precision airfoil really make a difference? Probably not, the better pilots always seem to do better.
I don't see any reason why you couldn't use a 3D printed leading edge or control surfaces.

It's something I will talk to the Wings Over Wilson president about to see if we want to modify the rules to allow 3D printed wings. I don't think you will get as smooth of a surface with 3D printing as you get with iron-on covering. 3D printing is a fairly heavy process, so weight/strength may be an issue even with carbon rod reinforcement. If we get enough interest, we can make another contest class. 3d Printed planes with a specified airfoil, 60" span, specified area, specified, root and tip chords, min/max length, and min/max weight requirements.

Mark

 

[m-dennis]

There was an ODR that had a forward swept wing made by Denny Maise called the Hammerhead. It had issues in the corners with tip stalling as I recall.

 

[Red]

There was an ODR that had a forward swept wing made by Denny Maise called the Hammerhead. It had issues in the corners with tip stalling as I recall.

So does that mean the planforms I drew above would all meet the rules?

 

[m-dennis]

Yes

 

[TyFlies]

Red, for what it's worth Erik Eaton is the local President who's designed a few ODR's. His Bad Voodoo Pro is based on planform A. The Cobra Hybrid has the same planform. He's told me a couple of times that he thinks that planform has the best combination of speed and turning performance. Really not sure why I'm telling you that since you might be a competitor -- You should probably go with the hammerhead : )

 

[Wayne]

Hey Mark, thanks for stopping in!

3D printing is mostly brought up to make for a low cost airframe. I honestly think spending some time to build a traditional construction model would be a far better investment of time. 3D printed models have very short life spans. With this said, there may be some better methods to play with that could alter that equation. For now, I'd say don't worry about it. Maybe in the future.

Planform - From my experience I would opt for C or E but at a 60" span it may not even matter.

I have no experience with any of the approved airfoils. The last time I played with any of them was probably in the late 80s. When it comes down to it, I imagine we will knock out several wings with each of the allowed airfoils and see how they do in real life.

To confirm, we can only pick from the approved airfoils, or is it the 9.5% that is the limit? I ask this since the S6061, S6062, S6063 are thickened to reach the 9.5. (I'd suggest staying with the preset foils since it is an ODR.)

I like this comment in the rules:

If you care to quibble about the relative camber of A vs. B, you’re taking this entirely too seriously!

But for me, this is the fun of the design. Building the best model to meet the class.

 

[Red]

Red, for what it's worth Erik Eaton is the local President who's designed a few ODR's. His Bad Voodoo Pro is based on planform A. The Cobra Hybrid has the same planform. He's told me a couple of times that he thinks that planform has the best combination of speed and turning performance. Really not sure why I'm telling you that since you might be a competitor -- You should probably go with the hammerhead : )

Thank you I appreciate it. Part of being a good designer is learning from others, so you won't find me not listening lol. I'm going to start drawing and see what I can come up with. Thanks for the help.

 

[iti20090]

Yes

First class,thanks

 

[TyFlies]

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.

 

[Wayne]

LOL