Model Boat Mayhem

Dry Dock / Shipyard: Builds & Questions => Yachts and Sail => Topic started by: alanmack on October 07, 2010, 05:50:40 PM

Title: Wing Ray design
Post by: alanmack on October 07, 2010, 05:50:40 PM
Can I test your memories please? Can anyone remember the Vic Smeed design Wing Ray, a wingsail model of about 1980 vintage. I don't need the plan (even if it is still available) but I'd like to read up the notes that presumably went with it. But despite years of searching I cannot trace which publication it appeared in let alone which issue. Please put me out of my misery.
Title: Re: Wing Ray design
Post by: andrewh on October 07, 2010, 06:09:30 PM
Alanmac

Memory still perfect, recall shot to ribbons :}

I have the article in a copy of RCM&E and its in the loft - I will try and lay my hands on it!

andrew
Title: Re: Wing Ray design
Post by: dreadnought72 on October 07, 2010, 07:11:31 PM
Memory still perfect, recall shot to ribbons :}

Mmm. I know that one.

Trying defragging the wetware, Andrew!  %)

Andy
Title: Re: Wing Ray design
Post by: andrewh on October 07, 2010, 07:40:15 PM
Andy
I did the briandisc analysis and find that I'm left-handed, lysdexic and 99% fragmented - and worse there is no space available to do the defrag.

It suggests that I delete some garbage and get a life :}

Alanmac - will head for the loft - have to get out my indoor aircraft anyway for Sunday!
andrew
Title: Re: Wing Ray design
Post by: alanmack on October 07, 2010, 07:49:08 PM
Thanks for that. RCM&E was the one mag I had discounted altogether - wrong prefix on the Plan No MM1311. What good service too! Eleven minutes for the answer.

Thanks again

Alan Mack
Title: Re: Wing Ray design
Post by: andrewh on October 11, 2010, 11:54:25 PM
Alan

Sorry to report - no success so far.  I have found EVERYthing except the right box

I will keep looking!
I remember that the hull was from a previous conventionally-rigged model; the rig was a symmetrical wing with balsa ribs and spars

Rotation of the rig was by means of two pulleys on the servo and mast in a 2:1 ratio so that sail rotation was 90degrees

more when I find it
andrew
Title: Re: Wing Ray design
Post by: alanmack on October 12, 2010, 09:22:55 PM
Andrew

I remember that the hull was from a previous conventionally-rigged model; the rig was a symmetrical wing with balsa ribs and spars

Rotation of the rig was by means of two pulleys on the servo and mast in a 2:1 ratio so that sail rotation was 90degrees

If my guess at timing is correct that will almost certainly be a Panache hull then (Free Plan Dec 1980) - probably on Vic's drawing Board at the same time.

I wasn't cjear about the pulleys and their ratiom so thanks for that information.

Alan Mack
Title: Re: Wing Ray design
Post by: roger on October 14, 2010, 08:17:17 AM
Hi guys,

This sounds interesting, so I tried a search of MBM for “wing sail”.

Of course there’s lots of “sail” references, but then I got drawing, following, chewing, showing, knowing, allowing, towing, bridge wings, swing-arm, harrowing, swinging, throwing, blowing, and screwing, … and then I gave up.

I guess I could try Googling but I dread to think what distractions I might drag up under the last two categories! %%

I have fancied trying a rigid aerofoil sail for a while (ie about fifteen years! :embarrassed:) but it has never got to the top of my to-do list.  I might be motivated to actually do something about it if you can help point me in the right direction.

Regards,
Jolly Roger
Title: Re: Wing Ray design
Post by: tigertiger on October 14, 2010, 08:35:06 AM
For general interest, have a look at Ivor Bittle's site.

http://www.ivorbittle.co.uk/Articles/The%20model%20wing-sailed%20yacht/The%20wing-sailed%20yacht%20for%20the%20web.htm
Title: Re: Wing Ray design
Post by: roger on October 14, 2010, 08:50:45 AM
Wow, thanks tigertiger.  I wasn’t expecting such a prompt and comprehensive answer.  I guess you’ve embarrassed me into doing something about it now.  I’ll work through the Ivor Bittle stuff and then get on with it.  I’ll get back to you soon.

JR
Title: Re: Wing Ray design
Post by: tigertiger on October 14, 2010, 10:46:34 AM
Glad to be of help.

Stay jolly.
Title: Re: Wing Ray design
Post by: Little Rascal on October 14, 2010, 04:02:05 PM
Hmm.

I don't wish to ruffle any feathers here...

But some of the aerodynamic theory in the Ivor Bittle site is rather shaky.

It very much depends on what size your wing sail will be (Reynolds number operation) but there are quite a few wrong assumptions in his method...

There I've said it now! {:-{ You may proceed to tell me why i am wrong!
Title: Re: Wing Ray design
Post by: tigertiger on October 15, 2010, 01:59:47 AM
It is easy to knock and much harder to produce something yourself.

If anyone would like to have a crack at producing some numbers please feel free to put them up on here.
Title: Re: Wing Ray design
Post by: Little Rascal on October 15, 2010, 12:13:24 PM
Tiger Tiger.

You are absolutely correct - I was not meaning any disrespect to Ivor, who is clearly a highly intellient gentleman. There is a lot of good information on his site and obviously he has developed his ideas with lots of empirical testing.

But I'm afraid some of his conclusions are based on wrong assumptions...

I am aware that I now need to explain why I say that - and yes that will require some effort on my part! But I don't want to hijack this thread either.

Briefly - his assumption on the operating alpha (angle of attack) of soft sails is not accurate - it is based on a misunderstanding of the apparent wind vs true wind. He says that all sails are stalled and the operating alpha is at least 35 degrees. That is demonstrably not true (and I would happily take anyone out on my sailing boat to demonstrate)

Ivor's recomendations for downwind sailing do not follow the method used in full size wingsails where the sail is still set up for a low alpha and lift is still produced as well as drag. This condition is hard to visualize but is shown here www.omerwingsail.com/driving-force/

The use he makes of the airfoil data is a little rudimentary - calculating Lift coefficients and angle of attack from wind tunnel data requires careful attention to the reynolds number of the wing and also a correction for aspect ratio. These formulas are in the public domain.

Many of the aerodynamic interactions between the sail and the trim vane are directly affected by the position of the pivot point for the sail, which (as far as I can see) is not given on the site. In aircraft design this point is analogous to the centre of gravity.

I want to re-iterate that I mean no disrespect to the gentleman, but I just wished to point out that the site is not definitive and I would use it with appropriate caution.
Title: Re: Wing Ray design
Post by: keven64 on January 06, 2011, 09:09:57 AM
The Wing Ray plan was definitely featured in RCM&E - maybe during 1982 ?
My memory is... err...

That was the only magazine I got - my Uncle got Model Boats and Aeromodeller.

I also still have a copy of that magazine - but I've no organisation skills whatsoever - so there's no point me looking for it as I've no clue where to start.
It might turn up unexpectedly...

Keven. :-)

Title: Re: Wing Ray design
Post by: alanmack on January 06, 2011, 01:34:14 PM
Keven
         Thanks for the input. The date should be about 1980 by the MM No. but they can "drag" one way or the other if the draughtsman gets the number issued early or a retrospective issue to a popular free plan. I shall braoden my search into 1982 thabks.

If you can't find it please keep a watching brief as I'd like to acquire a photocopy of the article.

Alan

Newport.
Isle of Wight
Title: Re: Wing Ray design
Post by: alanmack on January 10, 2011, 07:58:49 PM
To all who contributed

Thank you all. I have now located a copy of the right issue of RCM & E, August 1980 as expected for date.
Now if i can only buy the thing successfully.

Thanks again to all

Alan Mack

Newport,
Isle of Wight