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Wittman Tailwind W-10


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I enjoyed reading this article in RCM&E this month. Could I ask a question of Peter Miller or anyone else with knowledge of these matters. How do you calculate the wing area of this model? 360 sq.ins seems a bit ambitious to me looking at the dimensions of the wings, which are rather small. Each wing is only 21 ins long with a chord of 8 ins max including the ailerons. Discount the taper sections and I can't see even 300 sq.ins. Is the tailplane included?
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Yes, Tim is right, one simply takes the span and multiply it by the chord. I did allow for the tapered tips. The other way which is just as accurate is to take the area of the full size and divide by the scale of the model.
 
So, full size are in feet X 144. Square root. .divide that by the scale of the model 1/5th and then multiply the result by its self. That give the correcdt area as calculated byt the orginal designer.
 
The fuselage is going to lift quite a bit as well on this aircraft.
 
Tim: Young Peter? Er how many decades ago was your avatar picture taken
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Posted by Peter Miller on 07/07/2010 08:11:02:

 
Tim: Young Peter? Er how many decades ago was your avatar picture taken
 Just celebrated my 154th birthday........
 
Still haven't had a chance to have a good look at the Wittman plan yet, but it looks ripe for 250-300 watts if you ask me!
 
tim
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Still haven't had a chance to have a good look at the Wittman plan yet, but it looks ripe for 250-300 watts if you ask me!
 
tim
 
If I build it it will be electrified but with some serious reduction in weight, as mentioned in the write up, how about   a 48oz auw? 
                       F8 

 

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Thank you Peter and Tim.
I asked this because a few years ago I asked a similar question about the Keil Kraft Southerner 60 (Ben Buckle), in the R C Groups, a project I have been nibbling at for ages. This plane has a very slim fuselage but a very large (2ft span) tailplane. If anyone can guess the wing area I would appreciate it.
Or maybe I should have started a new thread.


Rob
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You know when I need to know something I use the internet. I know that this may seem strange but it works.
 
You ask about calculating the area of the Southerner wing. This is basically an elliptical wing, or at least a lot of it is.
 
If you google " Elliptical area calculator" you will get pages of the things.
 
If part of the wing is parallel work that part of the area out as per normal. then use one of the calculators to work out the elliptical part.
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  • 5 weeks later...
Yes. Bind it with the copper wire and then flod the wire and tube with solder.
 
TIP! I take a length of wire and fold it about three or four times to make a cluster of wire and feed that through the holes and then twist the ends together. Much quicker and easier that threading the wire round and round through the holes.

Edited By Peter Miller on 07/08/2010 08:35:51

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  • 2 weeks later...
hello Peter,
as along time reader of RCM&E i always look forward to your plans for somthing new and exciting. i have built the Thomas s4c Scout and it was a delight to fly as i like to turn up to the local feild with somthing no one else has this was very much drooled over.So for my next project the wittman tailwing i have already started the plane with the wings done and elevators and half of the fuselarge done,i have a OS LA .20 Blue which will be mounted in and also she will be clothed in pro film blue and white.
the wings attachment system that you used with the rubber band has been replaced buy using the paper tube which the servo wires went through, i have used a carbon fiber rod which locates right through the fuselarge and instead of two dowls i have use 2 plastic wing srews into each wing for location. i havent added the flaps just single alerons with flaparon mixing on the JR X2610 System that i use i hope these little modifictions dont upset you too much Peter i am going to add som photos of the build ASAP so other ppl can have a look yet again i must say building form scratch is a dieing art dont let the ARF take over too much although they are fantasic......regards Daniel Cope Tasmania Australia.
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I don't have any shots of the motor mounting but it is prestty simple, side mounted on a nylon engine mount. You may  want to lengthen the mounting box as the two stroke will be much shorter.
 
Not quite cleare about your wing mounting modifications, Whe you say Dowels do you mean the wires? Also, how do you replace the elastic band with the paper tube?
 
I don't mind what modifications you do to my plans...Just don't complain that there is anything wrong with the model if they don't work!
 
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lol  no problems peter,
ah well then sorry for the confusion i have made extra holes in the ribs to run the aleroins wires in,  the paper tube that shows on the plan has now been made out of light carbord tube which also continues through the fuselarge,then i have crafted a carbon fiber rod which inturn  slides throught the fuselarge and ito each wing kind like the segull models wing  system if you have seen them? oh and the wires the wires yes sorry its the australian slang comming out lol, i have replaced these with wing screws with blind nuts so each wing is supported with a twin locking nut where the wires would normaly  run as i fly in wind most of the time i just like to have the sense of srewed and braced wings on my planes i am not by any means stating that your plans are not good enough by any means as i worship your gift as a model designer i am just not worthy of such greatness peter.. i guess i am the guy that just has to make it over strong.....thats all.
oh i have never changed any of your plans before.
i cant wait till your next plan peter i think i just might be your greatest tasmanain australin fan!!!
and thats not electric pedastool type with the varibule speed setting.............
ps as soon as i get back to the ranch i will add some photos for you so you can see what i mean as i am on holiday down the south of antactica eg OLD HOBART TOWN  you know convicts..
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I can't think of many people who do NOT change plans to suit their own ides and that is the first step to designing. The next step is to take a basic aerodynamic layout and add your own shapes round it, then copy the construction methods that you prefer onto the plan and guess what, you just designed a model!
 
Trust me, designing is not a gift, it is basically rule of thumb and experience. Anyone can do it.
 
I am a very lazy builder in that I like to make things as easy as possible for myself and over the years I have developed methods and also adopted other peoples ideas to make life easier.
 
Of course this shows up in my designs, after all, I have to build them first.
 
 
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  • 2 months later...
Yes, In hind sight I would suggest stronger saddles. When I thumped mine in in a field due to a sick engine (It didn't like the fuel that I was using) one saddle broke.
 
Under normal use they are probably strong enough. The RV3 is a much heavier aircraft and there is only one saddle for the two legs so I knew that they had to be stronger.
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