N1EDM

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Hi Lou,
I'll look up your vacuum forming technicques thread... I could use some information on that. Thanks for the tip. And, I should have recognized the Mosquito. That looks like it will be a nice flying airplane. I like your test bed too. I'm trying to read the writing on the wings... It looks like it says "Wild Rebel". Am I close?

I just realized that you didn't know that I switched projects. Still a Golden Age racer, but I got my hands on a Joe Bridi kit, a Brown B-2 (aka Miss Los Angeles) with fiberglass fuse. I'm still working on the Marcoux-Bromberg scratch built, as well. But I thought I'd use the MLA to 'practice' on for my first Scale project, rather than go whole-hog scratch built.

I'm having 2nd thoughts on the engine. I have a new Saito 100GK earmarked for it. But it may be too long. I may have to switch to an OS 91 or 61.

I got way-lay'd a bit, but I should be back on track (don't worry, it was all R/C stuff. Helping with an Auction, helping to run a Fun-Fly). I'm almost done with the AutoCAD files, so I'll be able to ship them off to the laser cutter in a week or two, I think. I have to make up a small section of wing to make sure that it fits into the saddle OK before I commit this thing to being totally laser cut.

Steve, thanks for the calculations... As for SWAG, it's a "Scientific Wild-*****ed Guess"

BWooster

"Wild Rover" - (an Irish folk song). I'm going to mold a new canopy for it with the vacuum former. Also, some wheel pants.

As for the Mossie, I'll post some progress shots in a few days...

L

mrfx2001

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I have some experience with both s8036 and eppler airfoils having build my foam cutter and playing around with combat and flying wings. Eppler is ok till the power goes away. Then you have to fly it. The selig 8036 turns into a slope flyer the moment the power goes away and I have no reservation flying in 30mph gusty wind with this airfoil.
Fred

BWooster

I have found the same with the Eppler 197 and Selig 8036.

Here are the progress shots for the Mossie.

N1EDM

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Thanks for those observations on the 8036 and the Eppler. I've never used an Eppler, and you two probably just saved me a ton of work.

Thanks,

Bob

BMatthews

I have a 2 meter electric glider with an Eppler 201 on it and it is a GREAT airfoil. Good speed range and carries the weight of the old school electric motor and batteries very, very well. 56 oz for a 2 meter is definetly up there but this thing thermals as well as any model I've ever had and speeds across the sky when needed at the same rate as a typical overpowered trainer at full throttle. I can heartily recomend it but it's got enough camber that it would be best used where there isn't much inverted flying, if any, planned. The wings have just a skosh of washout in them but the model is still highly resistant to tip stalling even in tight slow turns.

BWooster

Bruce,

I think the most significant thing about the Selig is that it is a 16% airfoil. If the Eppler 197 were changed to the 16%, it would perform much the same way. It looks like the E201 has even more camber.

I think the S8036 is slower, but that only makes sense.

Lou

N1EDM

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The Selig 8036 is a power plane airfoil. I think that you're comparing apples to oranges here. The Eppler 201 sounds like it's optomized for sailplanes. It might be more prudent to compare the Eppler 201 to a Selig 7000-Series airfoil.

Which Eppler foils would you use on a power plane?? I haven't used them much, so I don't know what to look for

Bob

BMatthews

You guys are quite right. I guess I should have explained that my praise of the E201 was just to show that not all Eppler airfoils are nasty things. They were and are popular for a very good reason. But there are so many that perhaps it's hard to avoid a dog here and there.

Anyway, I totally agree that for a power model that will see some inverted time something like the 8036 is the way to go. But there's possibly some Eppler options that are equally as good. But to save time go with the proven track record that the 8036 seems to enjoy.

MSelig

When people ask me, I've been recommending the S8036 for sport-type
airplanes that need a semi-symmetrical airfoil. From our wind tunnel
test data, the lift curve takes a long time to roll off into a stall
break, so there's a lot of warning that a stall is about to happen.
This seems consistent with things I'm hearing from people who have
used it. Of course, airplane stall is mostly driven by the wing
planform, so the airfoil is not everything.

And someone asked in this thread about do I get royalties for these
airfoils. That would be nice, but I don't. I tried that once long
ago, and it was more trouble than it was worth!

Michael

N1EDM

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Hello Michael,
I'm a large fan of the 8036. Have used it twice so far, and plan to use it on a scratch-built scale plane (Marcoux-Bromberg Racer).

I notice that Top-Flite uses the 8036 airfoil at the root and 8037 at the tip (with a touch of washout) on some of their kits. I'm considering that.

I also have a couple more questions, but wonder if they are appropriate in this thread, or if we should start another thread? I'd like to find out more about the 8050 and to find out if you have other power-plane type foils that you've developed.

By the way, I saw you on the History Channel when you helped to figure out if Lt. Brown was really the guy who shot down the Red Baron. You were very convincing. Enjoyed watching you there.

Bob

BWooster

Sorry, I gotta ask: did Roy Brown shoot down the Baron?

And for a supplemental, who was the Baron shooting at?

N1EDM

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If I remember the story correctly, the Baron was, at that point, running. He couldn't shake Lt. Brown. They never conclusively proved who actually shot down the Baron, but the overwhelming concensus was that he was killed from ground fire - possibly from an Australian infantryman who was posted in the area. But, for various reasons, they could never pinpoint it to a specific individual. I think that this Australian chap died before they had a chance to talk with him to get his report of the story.

If Dr. Selig drops back in, perhaps he could correct my story if I got it wrong.

Bob

BMatthews

My understanding was that there was a fair amount of ground fire as well as Roy Brown taking potshots at the Baron. A study of his wounds would probably have shown who did it but in the end it was awarded to Roy Brown I think just because he was a fellow airman and an officer and thus it made for better press than if some unknowable and unacertainable foot soldier was the actual cause of bringing down the Baron.

But we digress....

Hey, how 'bout those airfoils, eh? Who wants to be first to make a modern FAI pattern ship using a Benedek 7407?

BWooster

(The Baron followed young Lieutenant May down. Brown followed the Baron in pursuit. Young Lieutenant May was later known as 'Wop' May, the famous Canadian Bush pilot (and a resident of this fair city!))

Now I'm off to find out what a Bendek 7407 is...

BWooster

(Also, I'm pretty sure it was Captain Brown)

N1EDM

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I believe that the wounds actually did show that the trajectory was from ground fire. There should be something on the Internet, I'm sure, confirming this.

I was wrong about the source though. It was on the Discovery Channel, on History's Mysteries, and it was called "The Death of the Red Baron". Unfortunately, I can't find a source for this on any video, but hopefully it will play again now and then. There was a mention of it on another link as well

http://www.rcgroups.com/forums/showthread.php?t=79229

But, back to the thread...

What is a Benedek 7407? Does anyone have a source for coordinates for it so that I can plot it in AutoCAD? Is it a symmetrical or semi-symmetrical wing?

Bob

BMatthews

It's actually a thin and highly undercamberd free flight airfoil. But I got you thinking and back on topic again didn't I... Stick with the 8036 root and 8037 tip option.

BWooster

Speaking of thin and highly undercambered, do you know of anyone trying to model an RAF 15? I'm thinking my next project might be an SE-5a, with a scale airfoil. Judging from photos, it is something like an RAF 15, but I can't find a source.

Also, any pointers on building such a beast, given there is so little depth?

BMatthews

How large were you thinking of makeing it? If you insist on keeping it that scale then I suggest you go all the way and make the rigging functional. Then the spars only need to support the compressive loads transferred to them by the rigging and the bending loads that occur between the fuselage and struts. The only cantilevered loads occur in the tips beyond the struts.

BWooster

Probably a wingspan of 45" or so. I'm thinking about a .30 Saito.

I have to finish the Mossie first, so this is next year material. But it never hurts to start thinking ahead.

BMatthews

For that size I would definetly consider a one piece model with functional rigging. And there's no reason why it could not be a stick for stick build that faithfully follows the original pretty much. Overall it would look wonderful and come out lighter than the usual sheet adaptations.

But then I LIKE building with sticks....

MSelig

The S8036/37 is a good combination. The S8037 tip section was
designed for slightly lower Reynolds numbers with the same focus on
soft stall. If it were me, I'd use the two airfoils together, but
going with the S8036 alone is not that much different.

As a bit of background, the particular specs including the soft stall
came from David Ribbe when he was designing the Top Flite P-47 while
working at Hobbico in ~1995. Now David Ribbe works at Horizon
Hobby.

For those interested, in 'recent time' I designed a new Q500 section
(S8064) which is used on the Hobbico Viper. I've not been following
the Q500 scene so I don't know how well it's working for them.
However, we did wind tunnel test the section, and now I just need to
finish up the next volume in the series (actually we have Vols 5 and 6
to finish up) to get the data out there.

There's also the S8038 -- thinner and less camber than the S8036, but
still very close stall-wise. This airfoil was designed for David
Ribbe's MiG15, which just one the 2005 US Scale Masters Championship.
(I don't think the airfoil had a lot to do with it!)

As was posted, here's a good link for the Discovery Channel stuff:
http://www.rcgroups.com/forums/showthread.php?t=79229

Michael

BWooster

Count me as one of those. I'm grateful for your input.

N1EDM

My Feedback: (2)

Same here, and I'll be interested in Volumes 5 & 6.

Thanks a lot, Michael... Appreciate your input. Love those wing sections. Have a Happy Thanksgiving

Bob