Basing a home desgn on the famousWOT 4

[Myron Beaumont]

I've never seen one !! Honestly! BUT with bits of info I have a sheet of brown paper in front of me to design something similar (not spending £90 when I have loads of wood in stock). Is it the wing section & / Or the swept back tail feathers  / or the concave rear fuselage bottom ( the fuselages profile of nearly an aerofoil ) I shall be using an OS 52 Fs with the 52 " span . Any comments from all you owners with tips very welcome .

G-UMPY

[Steve Hargreaves - Moderator]

Like all good designs Myron a Wot4 is greater than the sum of its parts.....they fly well & just feel so "right" in the air.....you can go completely mental with them & throw them around the sky & when it all gets too much slow down, throttle back & it becomes a trainer again!!!

 

A truly great model........it must be to have survived so long!!!

 

I've no idea what makes it so great but I think the wing section is a bit trick...Mr Foss was a glider man initially & I reckon he knows a thing or two about wing sections....certainly if you look at the wing section it is semi-symmetrical but seems to have a certain amount of reflex built in......as you might suspect I am neither a model designer nor a aerodynamisist!!!!!

[Myron Beaumont]

Steve

Yep I think it's to do with the wing section .Having printed off an article about converting the model to 'lecktrik I managed to see the first 3/4 of the wing section - It's very similar to my "Ruperts Dad"  -Very rounded & very thick .Don't know about the reflex though .Can you explain ? Is there maybe a bit of washout incorporated maybe ?? & is the tailplane a flat plate section or a symetrical ptoper section ?

[kc]

 

It's the wing section and wing quite near to the engine thrust line.  The wing tips, tailplane, fin and rudder are all different in various versions, but same flying qualities.The origianl plan Wot 4 is said to have a different wing section to the kits.  Its the balance of all tailplane areas and wing and everything just right that makes it a good flier.

 

 

.Virtually the same wing section is used on the Wight Crusader a design by Keith Humber ( Radio Modeller plan ).  The chord is about half inch shorter and span an inch longer so same area.  Crusader is mid wing & has the wing very close to the thrust line.  Excellent flier too, about the same as a Wot4 but certainly not better.

 

The free plan of the Maricardo a few years ago looks fairly similar to the Crusader and is said to fly really well like the Wot4

[Myron Beaumont]

KC

Thanks for info . According to what I've found ,the wing c/l is two & a half inches above the thrust line ! & they are parallel !

[Steve Hargreaves - Moderator]

The tailplane & fin are simple 1/4" sheet ....the wing as you note is pretty thick in section. What I mean by reflex is that looking end on to the wing from the leading edge it curves quite steeply during the initial third (as you would expect) & then tapers away to the trailing edge again as you would expect but at about 2/3rd chord it flattens out slightly.....difficult to explain...a picture would be worth 1000 words but alas no pictures!!!

 

Also the top of the wing is flat whilst the bottom tapers out to the tip thus incorporating a slight amount of dihedral into the wing...

[Myron Beaumont]

Steve

Are you talking of the tapered wing version (I think ) Don't really understand your description 100 % I can't post photo's either  It is like a kind of wash out isn't it ?

[Myron Beaumont]

Steve

Just realised what you were saying . If you build a wing upside down with a tapering /thinning depth /section you end up with a little dihedral .I always build like that .on low wingers .

[kc]

The Wot4 tailplane is flat and from 1/4 inch balsa.

 

Wot4 section is quite similar at the front to a ' Kaos' section. But somewhat modified at behind 25 per cent of the chord I think.   Super Kaos and Kaos use a tapered wing though.

 

The Profili software can print out  a 'Trainer 60 ' section which seem identical to a Kaos and of course can be printed to any size.

[Myron Beaumont]

KC

Ta !

Next question -Is the TE of the tailplane squarish or thinned down with a gradual taper .On my 3-D thing it's meant to be squarish

[Steve Hargreaves - Moderator]

Myron, its a typical sheet tailplane....rounded at the edges!!!

[kc]

The Wot4 is much,much thinner than the Rupert's Dad at the TE

Nobody knows the exact wing section because there is no plan in the kit. People have just drawn around the foam wings to get approximate shape. Also nobody knows exactly whether there is any incidence, they just have a fus side shaped to the wing.

The latest Wot 4 is called Classic & seems to use the Acrowot fin and rudder and also a sub fin.

Tapered wing Wot4 is called Mark4

 

I am referring to the Wot4 Mark2 which has a tailplane 18 inches by 4 tapering to 2 inches at end.  Then there is a  tip added which adds another 1inch each side. Total span 20 inches.Tip is rounded at the front and square at TE. tips are 4and a quarter inch long so it projects to TE of elevator( beyond main tailplane) 

Tailplane LE is 28 inches behind Wing LE

Elevator is  8.5 inches long each half. 3 inch  wide at middle and 2 inch at tip  Cut away for rudder is 60 degrees from hinge line so TE is 7 inch long.  Some Wot4 have the elevator right to the tips ( ie no wing tips projecting but same same shape and width )

Rudder is 10.5 by4 inches narrowing to 3inches at top.  top is rounded

Fin is 6.75 inch high by 4.75 wide triangle plus  an inch which goes into fuselage. So it is made from a 7.75 by 4.75 1/4 balsa.

Engine bulkhead to rudder hinge line is 35.25 inch

Wing LE is 3.5 inch behind bulkhead

wing is 1.5 inch above tailplane datum line

 

[James Styles]

hi i built a acro wot from scratch well a plane that looks like a acro wot. all chris foss planes have the CofG. good luck with the build. if you need to know the CofG for the wot 4 let me know and i'll find it for you. Jim

[Diamond Geezer]

3-1/4" from the l/e

[Myron Beaumont]

Never expected such a thoroughily brilliant informative response from the three of you .Doesn't half make things easier

Thanks so much .Will keep y'all posted on progress .

Just thought of something else-Is the Mk 4 tapered wing 56 " span -not 52"(paralell chord ) ?

[kc]

You could design your own model or you could save a lot of time and get a copy of the March 2006 RCME with the free plan for Mike Keays ‘Basic 3D’ which has almost exactly a Wot4 wing section.  Can be made 58 span or clipped wing version 52 inch span.  You could buy the plan from MyHobbyStore.com  number is RC2028  price 9.95 pounds.
I have only seen one Basic 3D fly and I reckoned it flew just as well as any Wot4 I have seen.  It was the 58 inch span.  Model is just a bit bigger than Wot 4 all round and has built up tailplane & rudder.

Alternatively Mike Delacole’s ‘Rival ‘ design seems simpler to build very sleek Wot4 substitute and is 55 inch span with slightly thinner 15 percent wing section.  Free plan in August 1993 RCME.  Plan RC1721 price 9.95 pounds

Wot4  CG is 3.5 inches back from LE plus or minus quarter inch   ( I am referring to straight wing  type ) 

Tapered wing is longer span maybe 56 but it could be 58 like the Acrowot.

 

Myron.  send me a PM with an e-mail address and I will send a sketch showing dimensions.

[Myron Beaumont]

Kc ( or anyone out there) All I need now is the wing chord for the 52" paralell chord wing version -which is probably the same as the 56" tapered version I would expect . The rest will be all my own design so as not to break any copyright thingies .Not only that -I just love doing it !!  Too windy up here for flying anyway . Bet the sloapies are having a ball !

In his element

G-UMPY

[kc]

Myron.  See the e-mail I sent you with this info.  But the tapered wing is completely different I think. 

 

I assume you have   .com     at the end of your address!  ( you missed that out! ) Anyway i sent it to  the address you gave with   .com    on the end.

[Myron Beaumont]

Kc

Got the message - Thanks & have replied

[kc]

Myron,  I did not receive your message

[Myron Beaumont]

Kc

I necer seem to get things digital right but the good news is that withyour help the plans are coming on great -Really enjoying it !

[kc]

Originally this thread was about building an equivalent plane to a Wot4 for less than the kit cost of £90.

So I decided to work out how much the balsa etc cost to build a Wot4 if one has the plan.

Well the cost of the fuselage & tail balsa at Balsa Cabin prices is just about 10 pounds. The kit wing is foam core but an equivalent built up wing cost would be about £14 The hardare included ( as supplied in Mark2 kits ) is about £16.

So the cost to build from scratch is about £40

Many people say they cannot build for the cost of an ARTF model.  Assuming you also buy wheels, tank, engine mount etc ( many will reused old parts ) then this adds another £10 and covering must need at least 2 rolls4ft Solarfilm costing 13 pounds.

 

So the cost of building when buying everything you get in an ARTF is £63   compared to the £89 advertised cost of the Wot4 ARTF

 

Conclusion it is cheaper to build but not by very much if you buy everything new.  If you have the plan &  reuse parts then it is less than half the cost.

[Myron Beaumont]

Kc

Point taken BUT

 I have more than enough balsa in stock -the wheels- the plywood -loads of sruce spars-the Spinner -the piano wire for my undercart-the engine mount -left over covering materials (solartex & solarfilm) -fuel proofer-horns- clevises- snakes- screws -nuts& bolts-propellors- various adhesives-even a fuel tank (2" X 2" X 4" )-servos- lite ply (not that i'll probably use it )

In other words I can't think of a single thing I have to go shopping for . The whole exercise is to use up what I have & most of all enjoy designing it -which I have done all day -only the wing to go --The easy bit !      Plus just how many formers to put in the tail end of the fuselage . Being as it's 1/4 " stuff top & bottom ,it's going to be strong anyway ,along with the underside curve & of course the 1/2 " front fairings & 1/32 " ply side reinforcement in the whole of the nose area.

The whole project is really for the satisfaction of "doing it myself " for nothing .

Thanks again for a bit of guidance !

[Myron Beaumont]

Just read that the ideal engine is an Irvine 53 . I was going to install my OS 52 Fs  ,What does an owner recommend ?.I do have said engine as it happens but thinking of keeping the noise down .

Bearing in mind that my design  "MYWOT " is only loosely based on the real thing & it has come to my notice certain little differences in the various Marks just looking at photos.

Some have a subfin plus tailwheel others not so 

Wing tips vary from the angled underneath  flat end (good for dodgy landings ! ) (as per Tyro etc.) -Others have the same slight swept back look but with the covering material stretched over the last couple of inches or so as is the "norm"

Has anyone any idea what effect these have on performance ? I personally like the curvy sub fin which I'm sure would improve knife edge performance.

 

(now have a proper Samsung camera from Boots by the way (1/2 price ) to record progress . Not much good showing sheets of brown paper with loads of lines on at the moment but should interest some of you soon-let me know .)

G-UMPY

 

[kc]

A Wot4 flies on anything from a 30 two stroke upwards.   A .40 plain bearing two stroke like OS40 FP is perfect for normal aerobatic flying.  Only maniacs need .60's !

All depends on weight but 4.5 pounds is normal.  A 52 four stroke seems OK , but the Irvine 53 2 stroke would be for exciting flying.

 

Wing tips don't seem to make much difference. 

If you made a wing tip of white foam shaped to the airfoil and then sliced it off at an acute angle  underneath it produces a nice rounded tip which could have the wing sheeting continued on top and a flat piece balsa underneath.  Similar to later HiBoy wing tips.

Otherwise  sand a piece of white foam to a rounded tip to fill out the tip fillets and film cover the foam.