GliderIreland - Ireland RC Forum - Flying Model forum in Ireland
Gliders => Slope Soaring => Topic started by: joe on September 22, 2009, 17:41:45 PM
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So having gotten a bit bogged down and lost a bit of interest in my other projects for the moment. I decided to distract myself with something completely different.
The idea is to design and build a simple basic flying wing purely for racing/DS. Just for fun and a bit of design/building experience and also with the idea that if we get round to doing some foamie racing that a cheap wing that I can cut might be a good thing so people can give it a try for very little cost. Maybe racing with one design could be a goer too as then it is just down to the pilot.
So this is to be just a tester, the first of many I would imagine! I set myself a couple of rules. Main rule is not to get bogged down it this. Just do it. Finish in two or three days max. I must use the first wings that are cut and not faff around with cutting cores. It must be cheap. So I am using blue foam and a pine spar from the local DIY (EPP version once I get a design that works). Use stock trailing edges. TE stock i have is not really the best but, see main rule.
Design 1.
Very simple swept wing. Central or twin fins. Profile PW51. 1500mm WS (59")
Basic planform.
(http://www.gliderireland.net/forum/images/uploads/joe/ISW09.jpg)
Cut wings and glued together last night. One wing profile is a bit messed up towards the wing tip but, I stayed true to my rule and used it anyway(hope I don't regret it). Have made good progress so far today. Will post some photos later.
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Okay Joe, sounds like a ‘sound’ concept. :lol:
Are you designing this wing yourself?
I’m sure there are rules about the size and position of the fin on a swept wing, but what the hell……I’ll have one.
Profile PW51 seems like a good choice. (Er,…..What does it mean :?: ?)
Cheap is definitely good! (I can understand that part :D )
If winning with these wings is all down to pilot skill, there seems little point just you and I flying against each other. :roll:
K.
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Hey Keith.
Already designed and half built.
Yes size and position of fin/fins will be something that needs sorting. I have done two fins at the moment but will also make a center fin and try both. There is also area, aspect ratio, profile etc.. All interlinked. Lots of questions here but, what the hell. It's just a little experiment. Quick design and lash it together.
I not being precious or particular. If it flies, great maybe it's something to work on further and if it's a dog then I haven't spent to much time on it. Either way i'll learn a few things along the way.
PW51. Well the guy is called Peter Wicks and maybe this is his 51st airfoil design?? It's a profile used a lot for fast flying planks. Hopefully it will work on a swept wing ok too.
I was thinking MoM (man on man) racing Keith :? At least two machines racing at a time. Lots to go wrong. A bit more fun than timed. Miss a turn and you need to fly an extra lap etc.. If nothing else it would be fun and make us better pilots.
Got a few hours on it while Ellie was at play school. Did I mention I love play school :D :D
(http://www.gliderireland.net/forum/images/uploads/joe/P1050034.jpg)
(http://www.gliderireland.net/forum/images/uploads/joe/P1050031.jpg)
(http://www.gliderireland.net/forum/images/uploads/joe/P1050033.jpg)
Should be ready tomorrow if I can get some more time on it.
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Who’s been a Busy Bee then? :clap:
Looks GREAT! A thin (fast) profile, :D
When do you think you’ll be ready to take it up Big L? Joe
(You don’t really like Play School,….you just like all the Yummy Mummies that take their kiddies there. :wink: )
K.
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Hey Joe,
Sweeeetttt ! :D :clap: Can't wait to hear from the test flights !
Man on man race... :?: Calm down Keith ! :P
Anyway, I'm in ! :D
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Can’t help thinking that those fins look a bit small Joe.
I believe the nearer the fins are to the wing’s M.A.C. the larger they should be. The fins on your model look about the size of those on a Zagi who’s are much further back from the Zagi’s M.A.C.
Could be an optical illusion, or that I’m wrong. (Both of which are entirely possible! :oops: )
Guess the answer is to fly it and see. If you get a problem with yaw stability………make ‘em bigger
K.
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Hi Joe and Keith,
may be this site helps a little bit:
http://www.extremflug.de/seite097.htm
lots of pics, You don't need to read german.
Regards
Lothar
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What about omething from here:
http://www.knumoba.de/n_flugmodelle.php
prices look good...... group buy?
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Hey Keith.
They do look a bit smaller in the photo than reality. But you may well be right, they might be too small. The tips are probably the best place for them. For some reason though I've never liked the look of wings with the fins on the tips. I will try the center fin set-up as well as I like the look of that. The twin fin was the easiest to start with. The fins are not a big worry at the moment as they are easy to enlarge/move.
Will finish tomorrow and try to make a center fin to test as well.
All up weight will be around 700grams giving a wing loading of:
21 g/sq.dm(6.78 oz/sq.ft)
Thats fairly light which is a good start. If I can get it stable I will add ballast, which according to Peter Wick the PW51 loves!
Here's some numbers if anyone is interested:
http://fwcg.3dzone.dk/?wing_span=1500&root_chord=280&tip_chord=170&sweep_type=0&sweep=200&cg_pos=20&show_mac_lines=0
Maybe give it a go on Thursday Keith. You around?
Thanks for the link Lothar. Was wondering if this would interest you being a bit of a wing man.
Got a bit more done tonight. Basic fibre tape covering. Didn't worry about trying to make it really ridged. This is just a test model and if I fold the wings then it probably means it's flying OK so I won't mind too much!
(http://www.gliderireland.net/forum/images/uploads/joe/P1050044.jpg)
(http://www.gliderireland.net/forum/images/uploads/joe/P1050045.jpg)
To get an idea of how it would look with one center fin.
(http://www.gliderireland.net/forum/images/uploads/joe/P1050042.jpg)
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Once the basic design is finalised, what about finishing in the "new stuff" laminating film?
Might keep all the foam together in the event of mid airs!! (Who mentioned Keith??)
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Hi Bill
Must look into "new stuff". Heard a bit but need to do more investigation.
Don't worry Bill, Keith won't hit you if he's trying!! :lol: :lol:
The prices are pretty good on the site Bill. Apparently the "Frettchen" is a little rocket!
I reckon the materials for the wing have cost me about €10. Thats for everything. The EPP only for one wing would probably be over €20. I'd say I could do one with CF rod etc for €30-€35 which wouldn't be too bad.
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info on new stuff on RCMF & RCGroups. Its basically laminating film, as far as I can tell glued in place and then shrunk with heat. Seems to provide a clean strong surface
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http://www.rcmf.co.uk/4um/index.php/topic,52949.0.html
http://www.rcgroups.com/forums/showthread.php?t=790302
info on new stuff. Some UK based suppliers in the RCMF thread
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Must say it's looking very good Joe, I'm impressed :clap: :clap:
Okay for Thursday, but not till the afternoon, probably around 3pm. Okay with you?
("Wont hit you if he's trying,"......... :oops: .Blood cheek!)
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hehe! :D :D sorry Keith. Couldn't help it!
Not looking too bad. Looks like it wants to fly. And fast at that.
Thanks for all the links Bill. Did check it out 'bout a year ago but haven't looked since. Seems like it works well and it's not expensive. May be the way forward if I start cutting wings.
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Well, that went well! :D :D
Joe’s new design of a wing flew very well indeed. :clap:
No doubt Joe will be posting his thoughts of this afternoons flying, along with some footage we shot.
I put my Skua up against his new invention and it could match my wing’s performance. :!: But when Joe removed the twin fins and replaced them with a single, central fin, his machine really found it’s forte. :shock:
I’m talking FAST. :D
So me thinks my Skua will be loosing one of it’s fins in the not too distant future! :twisted: :twisted:
K.
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Congratulations on the successfull maiden ! :clap:
Photos, videos ????
So, what's the name of this new wing ?? :D
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"Blue Tit"
Explanation: It's made from Blue foam,......and a Tit is a type of Bird!
Joe has other ideas though :roll: (All of very anal inference)(Typical)
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:lol:
Smurf style !
Let's try to find a name :D
Blue Fart
The Blue Thing
Exosex (fly like a missile, Joe anal references style...) :lol:
M.C.A (but why MCA?)
...
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"Blue Fart"..............I hate to think of what you've been eating Fred
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(http://citronelle.c.i.pic.centerblog.net/jqgsmdo7.gif)
Hard to catch, but totally worth it ! :D \:D/
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What about something appropriately Irish like:
The Wild blue Rover (or toyota, ford, nissan!)
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“Blue C”
When spoken the name would infer Blue Sea. But in fact the letter 'C' is the international denotation for the speed of light!
Not very anal, but everyone apart from Joe would understand it :lol:
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Joe,
You going to do some in pink foam so we don't get accused of being sexist?
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Blue, Pink, Green whatever colour you like Bill!
Yeah! need a name now. All my names are a bit rude :?
So here's the low down.
Basically it flies pretty feckin' good:D :D :D. CoG was set at about 21% of MAC at the start. Ended up moving it forward in subsequent flights. It was very pitchy in the beginning as expected. Elevon movement for elevator is probably 5-8mm max. Became more stable as the CoG was moved forward but more reflex was needed on the elevons. Probably 4/5mm now.
It's pretty quick. Turns fast with no nasty habits. Inverted is good. Roll rate is not bad. Stalls eventually and just flops over. Stall recovery takes a while. Need to try this in light wind/lift.
No problem to keep up with Keith's S15. Hard to tell which was faster. Need to do a bit more flying to find out. He had his ballasted and mine was not (yet!). I say I was about half the weight of the S15
Started with twin fins. Worked good. No yaw issues that I could see. Seemed to track pretty well. Didn't have time to make a center fin so at the slope we just taped one of the fins onto the back. It was fairly floppy but I got the idea. Felt like it flew a bit better with one fin. Roll rate was a little faster too I think. There were some yaw issues but a proper fin thats not flopping about should fix this. I will go with the one fin design I think.
Came out reasonably ridged without trying too much. Pine spar and one little metal plate joining the spars. The blue foam is fairly resilient with the GF tape on top. If I don't plough it into the ground too much it should last a while.
Improvements??
Well the first thing that comes to mind is increasing the pitch stability. The PW51 airfoil is pretty pitchy apparently. I flies good as it is but that few mm of reflex is probably slowing it down. Would like to get the same stability with no reflex.
Thanks to Keith for the filming. Sorry for the quality. It's a still camera not really a movie camera.
[youtube]http://www.youtube.com/v/tT-xNSwOc5w[/youtube]