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Old Jul 13, 2003, 03:02 PM
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USA, WA, Seattle
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Question
What airfoil for this"SortaRF-84F".

Hey guys? I'm building a "SortaRF-84F". What airfoil would be recommended to use on this? It will be about 52" wingspan. Made from EEP. There will be no leading edge intakes and the wing sweep will be about 32 degrees. Fuse is done at 42". I want this to be a screamer! I was told go RG-14. But I wanted the wisdom of the "Go Fast Pilot/Builders" here.
Also...what the heck are you guys using for your digital pics. I can't afford/justify your usual digital camera. Is there something out there for less than $50.00? I would really like to start posting pics as your pics are most of my inspiration to get "the" project moving again...or start yet another one!
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Last edited by SpiritQuest; Jul 13, 2003 at 03:48 PM.
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Old Jul 13, 2003, 04:09 PM
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The fuse...

Sorry about the quality but here's the fuse.
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Old Jul 13, 2003, 04:29 PM
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Lyle, WA
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What I've found for foamies is that there is little real difference in speed between most modern airfoils with low camber, such as the RG's, SD 7003 and 7037, and a few others. The largest determination of speed in my experience is wing loading, so I'd include provision for ballast.

At table mtn N of Cle Elum yesterday, it was blowing 15-25 mph all day and as usual planes with similar loadings all had pretty similar speeds.

Looks like a neat sloper, next time we head out east in a few weeks I'll post an invite and you should bring it out!
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Old Jul 13, 2003, 04:51 PM
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Hey Thanks!

I'm trying to move this along as fast as I can. I chose an RG-14. Just printing it now. Affirmative on the ballast box it's big enough to carry 2 16 oz. cast lead ingots. I spend waaayy too much time trying to figure everything out. Sooo many unfinished projects. Gotta get it done while the inspirational juices are flowing. If nothing else, it will LOOK fast, that's for sure. I'm going over to Henley's to cut the templates today, if I can, he's got a scroll saw. Carving the canopy plug tonite.
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Old Jul 13, 2003, 05:50 PM
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Downey, CA
Joined Aug 2002
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I used a SD6060 on my F-86 & MiG 15 and works good. The E 374 also works well.


F-86
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Old Jul 13, 2003, 06:24 PM
That Freeking Laird Guy
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The RG-14 is best choice if you want fast. It's much thinner than the 6060 or the E374. With a swept wing like you are making make sure you put some washout at the tips. 4 degrees is probably about right for that sweep.

TFLG
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Old Jul 13, 2003, 08:43 PM
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Nashville, TN USA
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Digital Camera

I found a good deal at surplus direct .com. It was refurbished. Before that I would buy a disposable camera and have a CD made when developed. It only cost a few bucks at the local Pharmacy/store.

Good Luck,

Wayne
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Old Jul 13, 2003, 08:56 PM
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Lyle, WA
Joined Dec 2000
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Sounds good on the ballast. I hope you're doing some structural thinking about the box itself, that much lead will probably blow through the entire portion of the fuselage forwards of itself in a crash, unless you do some reinforcement. Even then, even with a foamie, that kind of speed may pretty much total it, and by golly you'd better have the spars from H*ll or you'll be fluttering the entire structure in turns.

Are you sure you really need 32 oz with only a 48" span? It may be that 16 oz is plenty. My 72" delta with 9 sq feet of area gets really difficult to climb when it has 30oz on it, and I'm sure your loading per ft will be way higher.
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Old Jul 13, 2003, 10:25 PM
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Thanks Guys!

O.K. Just got back from making the templates. They're RG-14...but no washout. I guess I was mistaken thinking that wingsweep = washout. And also was thinking less drag too...without washout.
Brian (TFLG) if you advise it, I can/will alter the template to incorperate 4 degrees washout. Easy enough. Glad you said something now. Thanks.
Mr.B...I did consider that SD 6060 ( along with a few others) for a bit but wanted thinner for all out speed
Chris (Mt. Goat) the ballast box will be kevlar thread/shoegooed binding around it and also to the CF rod that runs through the fuse. Honestly, I don't know how much ballast to provide for...32 oz. seemed like that HAD to be ENOUGH! Also consider the 48" span is closer to 50' and the wings are swept. The CF rod in the center is how I turned the fuse on my home made lathe. Worked dang good too! Just so you know the CF rod begins 8" BACK from the nose going to the tail, for obvious reasons! Beefy spars? Yes, I'm using CF spars in the wing but now I'm thinking that with 4 dgrees washout there maybe some torsional loading that may need to be addressed. How do I solve that? Any suggestions?
Now, I have a canopy plug to carve tonite. Hope to cut wings tomorrow!
TFLG get back to me on that washout...if you would I'd appreciate it. BTW I won one of your EEP Go Fast Me-109's on Ebay this week. I am looking forward to it very much.
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Old Jul 14, 2003, 06:28 PM
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....4 degrees!

Hey, TFLG 4 degrees seems like an awful lot! Just making sure before cutting foam. I'm checking on wing sweep too. I chose 32 degrees cuz a friend of mine who's done a number of wings says they start acting adversely going past that point in sweep back. Later edit: Y'know the RF-84F had anhedral in the wings too...hmmm.
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Old Jul 14, 2003, 10:49 PM
That Freeking Laird Guy
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Yup 32 degrees is a lot of sweep. The problem with swept wings is the tip stall. The more ya sweep em the worse the tip stall. You have a VERY swept wing. 4 degrees is probably not enough to be honest but I can't bring myself to add more than 4. When I ran the numbers for my F-15 wing it came back needing 6 degrees. I added 4 degrees and it seems to fly just fine at that. (it's an RG-14 also). I'm no aeronautical engineer so I'll spare you the techno-babble. Just trust me on this one, Add the washout.

TFLG
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Old Jul 14, 2003, 11:55 PM
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Roger that...

OK, wisdom speaks, I listen. I've drooled over your F-15. How fast is it?
Thanks for time and help. Back to the dungeon...
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Old Jul 16, 2003, 12:50 AM
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Mock up...

Just had to post something up today
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Old Jul 16, 2003, 12:59 AM
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One...

more.
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Old Aug 30, 2003, 04:27 PM
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Sneak peak...

Last crappy picture. I finally gave in and got a digital camera. Due to be here next week.
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