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Oct 17, 2005, 08:32 PM
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mistairjoe's Avatar
Sorry, I was born in a little town in Transylvania and i have trouble spawling. Joe
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Oct 18, 2005, 03:03 AM
can you land on that ?
Sorry Joe , I have no information on Transilvanian racing colours ! Nice pictures, have you got one of the Short "Crusader" ? The suggestions I put forward in my previous post was not intended to highjack the thread but to get some average modellers into the waterplane world. I think the planes you are all building/planning in this thread are magnificent and I`d like to see them round the pylons one at a time. Whether you time them or not doesnt matter,just to see them in action would be enough for me. A few years back our club`s annual Splash-in had a couple of fun races over the water. Five Bunch "Scorpions" vintage 1937/8 staggered round the pylons to much hilarity, the next race was for four "Northstars" was fast and furious. Great entertainment value if nothing else. Back on thread RCM&E magazine plans service do a 60 glo powered "Crusader" that might be scaled to suit your event.
Oct 18, 2005, 08:09 AM
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Martin Irvine's Avatar
Thread OP
I think we are looking at a "parade" rather than a race. It's mostly an opportunity to get a bunch of related scale planes flying together. Let's face it, there are not many Schneider Trophy racers built, in part because there are not a lot of waterplane events, and (generalizing here), flying sites are harder to find, harder to get to and a little more complicated to deal with. Several of the possible builders have not flown off water before - this may be the incentive to get them to try it. (It has me looking at other waterplanes, like flying boats.)

Martin
Oct 18, 2005, 01:05 PM
Designer/Builder
Jim Young's Avatar
Since modeling is not really a team sport, I'm in this because I think it's going to be cool to build along with a few others toward the same goal. While I wouldn't mind taking a few of you on in a race or time trials, I'll be content to let them parade by and fill the memory stick in my camera! Besides, I've watched Keith wax our club pylon racing champ's butt with my super slow Scatcat (half of the time he was flying inverted! ). There's no beating smooth thumbs.

Martin, I'm trying to figure out how to fit in a family vacation so I can make it to the parade.

Now back to the fun...

I've got Martin's 3-views scanned in and the outline basically done. These are the Hirsch drawings and I've never had good luck with his stuff. On one drawing he has the wing cord as 5.5', but if you measure it off the plan view it is closer to 6'. So, I'm doing a lot of fudging here and there. The cross sections are very small and it looks like they just used ellipses, so that's what I'm going to use. When you take off the fin and engine bumps, the S6B really looks like a pencil on floats!

I'm drawing this in AutoCAD full scale, and when I get the outline and all of the reference marks done, I'll scale it down to 1/7 or 1/8. I did some preliminary wing area measurements, and it looks like 1/8 will be a bit under 350 squares. So, my options are either stretch the wing a bit, or go for something closer to 1/7 scale. Since this thing is so skinny, I may need to make it 1/7 scale just to fit in the equipment.

Joe, where did you get those photos? Are they from Mr. Ozawa? He has to be some kind of 3-D artist. I love the one with the S6B and the M? side by side. The S4 looks pretty cool as well.

-Jim
Oct 18, 2005, 07:45 PM
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mistairjoe's Avatar
http://www003.upp.so-net.ne.jp/hirano/index.html Jim ,go to this webbsite. It is Hira Studios not Hideaki's although he was gracious enough to send me some three views of the Sm 51.I am still in a quandry as to what size i should make my plane. It is huge at about 44 inches because it's a bippe. It works out to be 655 sq/in total with the bottom wing at 37 in. Fuse is 47in. wing cord is 9 and 7in. No matter what it will be a floater, no pun intended. Jim what are your thoughts on airfoil, and how does your mono compare in size Joe.
Oct 19, 2005, 03:10 AM
Registered Snoozer
Neil Morse's Avatar
I'm just lurking here, but here's Hideaki's drawing of the Macchi that I found on one of the Schneider sites.
Oct 19, 2005, 05:36 AM
Designer/Builder
Jim Young's Avatar

Scale and airfoils


Hi Joe,

My S6B will end up between 45" and 51" with a 8" to 9" cord depending on the scale (1/8 to 1/7). This will put me into the 350 to 400 squares that Martin laid out. I would expect a Bipe to be around 35" span in this scale.

As far as airfoils, I'm not sure what to use for a Bipe. I've had a SuperSybolt and a Midwest Super Stearman both with semi-symetrical airfoils, but I'm not sure that would be right for yours. Undercambered would be very draggy and slow, but maybe not to bad it you want something leasurely. I need to talk to Keith about a few other things, and I can bounce this off of him as well.

On this subject, anybody have any experience with the RAF25 airfoil? That is the scale airfoil noted on the 3-veiw of the S6B. It looks semi-symetrical, and I could substitute just about any other airfoil for it, but I've used the scale airfoil on several other projects and they have worked out fine. I may go with a NACA M5, since the tail area is a bit small. The M5 has a bit of reflex in it so it has low pitching force and could be used on a flying wing. So, you don't need a lot of tail to keep it in line.

-Jim
Oct 19, 2005, 07:23 AM
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Martin Irvine's Avatar
Thread OP
Most of my biplanes have been WWI and a thinned Clark Y (down as far as 8%) has worked very well. I've also used as thick as a NACA2416 successfully. I'd also consider a NACA 2410. But as Jim says, what kind of flying are you planning for? From the way you have been talking, I think a thin flat bottomed airfoil like the 8%, (or 10%), Clark Y would be fine. I'm using a NACA 23012 partly for its low pitching moment to help with the small tail, and partly because I've used it very successfully in the past.

Martin

Martin
Oct 19, 2005, 07:34 AM
designer/builder
madrob's Avatar
Hi Jim,

The RAF25 is only 6.5% thick which seems pretty thin for a small plane. Not sure how well it would work for low reynolds numbers.

http://www.nasg.com/afdb/show-airfoil-e.phtml?id=971

I don't know about the M-5 but I do know that the M-6 has a very bad stall. The flow doesn't re-attach until 4 or 5 degrees below the initial stall angle. I don't know how it will react at these low reynolds numbers. I have used some of Martin Hepperle's airfoils on a scale flying wing with good results. Check them out here:

http://www.mh-aerotools.de/airfoils/index.htm

As for my airfoil, I had a friend run my model through his aircraft performance software that he wrote himself. He gave me a file with 138 differrent airfoils to choose from. the list has stall speed, max speed, rate of climb, minimum power, max L/D and a few other items. I was able to pick an airfoil that had a good speed range and should work well. Th funny thing is that the airfoil I selected is only 4 km/h faster than the Clark-Y. This is because the airframe is soo draggy with the floats, open cockpit and bulbous nose. I'll have to get a radar run done on the model so we can see how it compares to his estimations.

Rob

Rob
Oct 19, 2005, 03:22 PM
Designer/Builder
Jim Young's Avatar
Hi,

The RAF25 didn't look that thin on the drawings. I've had good luck as well with the NACA23012 on my little H-1, so that is the top choice right now.

Back to the drawing board,

-Jim
Oct 19, 2005, 07:04 PM
Registered User
mistairjoe's Avatar
Thanks, Martin and Jim.I will stick with the thinned Clark Y.AS far as my plane size question, i have scaled the SM 13 To 1/7 scale and it came to 45" wingspan, like Martin explained earlier about bippes versus monos.THat leaves me with a much larger wing area than 400sq inches. I guess i will stick with that.I will have to up my motor accordingly.Well back to the drawing board. JOe
Oct 22, 2005, 09:41 AM
can you land on that ?
Been quite in here so here is some inspiration.......Short "Crusader" for 61 2st Glo. Plans from RCM&E (MAP). On Loch Morlich .Inverness-shire.
Oct 22, 2005, 08:21 PM
Registered User
mistairjoe's Avatar
Nice plane Arrow. Looks cold in the photo. What part of Scotland are you in .Joe
Oct 23, 2005, 01:15 AM
can you land on that ?
I live about 30 miles south of Inverness. The hills in photo are the Cairngorms which has a ski area www.cairngormmountain.com The hills are only 4000ft high but we are at 57degrees north so get fairly cold winters. If you look closely you will see that the plane isnt floating but is on the ice ! It was designed by Dudley Pattinson founder of Flair Products and full-size pilot.
Oct 23, 2005, 10:18 PM
Registered User
Martin Irvine's Avatar
Thread OP
I thought those floats were remarkably "bouyant"!

Martin


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