Convair YF2Y-1 Sea Dart

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Phil Clark
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Convair YF2Y-1 Sea Dart

Postby Phil Clark » October 1st, 2015, 10:46 pm

In conjunction with 'The Little Jet Company', Fighteraces are building a large twin turbine US NAVY experimental fighter that can takeoff and land on water. The build begins...
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Phil Clark
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Re: Convair YF2Y-1 Sea Dart

Postby Phil Clark » October 1st, 2015, 10:54 pm

The second SeaDart YF2Y-1........this is the aircraft we will be modelling and the only one not to survive the programme. This had the twin ski setup like the first and proved very stable on the water which we hope we translate to the 1/4 scale model.
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Phil Clark
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Re: Convair YF2Y-1 Sea Dart

Postby Phil Clark » October 1st, 2015, 11:04 pm

The first task was to research the aircraft extensively. Starting with the obligatory Googling, plenty of dead ends were found but it did lead us to San Diego Air & Space Museum who have the archives for Convair. They were beyond helpful and without their valuable input this project would be that much harder. With plenty of original drawings we were certain we could achieve as close to 100% scale fidelity as is possible on an aircraft thats been consigned to history long ago. Along with the drawings we have plenty of historical high resolution photos that we can extract scale details from. A research trip took Alex from 'TLJC' & the client to Orlando to photograph and measure the SeaDart at the 'Sun n Fun’ Museum at Lakeland airport. This trip was essential as it unlocked some of the issues encountered replicating the ski retraction which is a geometrical nightmare and a huge project in its own right.

Much of the research showed the first SeaDart to be built which was the XF2Y-1, This was the "sugar scoop" aircraft in reference to the shape of the rear end with the Westinghouse J34 non after burning engines. Archive images, original drawings & the Florida research photos we blended together to give us all we needed to build SeaDart YF2Y-1, this was the second SeaDart to be built (with a different rear end & afterburning engines) and this went supersonic on 3 August 1954 in shallow dive from 30000ft. This variant was also used to develop ski design. Sadly this crashed on 4 November 1954 killing pilot Chuck Richbourg as he struggled to control a highspeed pilot induced oscillation which led to the aircraft going beyond its structural design limits.

The first SeaDart XF2Y-1
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Phil Clark
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Re: Convair YF2Y-1 Sea Dart

Postby Phil Clark » October 1st, 2015, 11:09 pm

Just two of several hundred photos taken at Lakeland, Florida..............
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Dart_LMA_3.jpg
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Dart_LMA_4.jpg
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John Greenfield
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Re: Convair YF2Y-1 Sea Dart

Postby John Greenfield » October 2nd, 2015, 8:01 am

Going to watch this one with interest Phil.
What motors are you intending to use ?

John

maurice northcott
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Re: Convair YF2Y-1 Sea Dart

Postby maurice northcott » October 2nd, 2015, 8:50 am

Beautiful aircraft Phil, loved it since I was a kid.

Looking forward to this one.

There was a Revell kit many moons ago if you can find one now - may help a little.

maurice

Phil Clark
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Re: Convair YF2Y-1 Sea Dart

Postby Phil Clark » October 2nd, 2015, 8:58 am

John Greenfield wrote:Going to watch this one with interest Phil.
What motors are you intending to use ?

John


A pair of Behotec 300's is the current thinking.

Phil Clark
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Re: Convair YF2Y-1 Sea Dart

Postby Phil Clark » October 2nd, 2015, 9:01 am

maurice northcott wrote:Beautiful aircraft Phil, loved it since I was a kid.

Looking forward to this one.

There was a Revell kit many moons ago if you can find one now - may help a little.

maurice


Hi Maurice

With you all the way......it's an awesome looking machine. I remember a photo of one taking off water in a 'coffee table' aeroplane book I has when I was 8 or 9......it's stuck in my mind ever since, hence we jumped at the chance of being involved in this project.

Not sure if it was Revell but we do have a small 1/48 scale plastic kit.......unfortunately it is a million miles away from being accurate so was of no use what so ever!!!!

Phil

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Re: Convair YF2Y-1 Sea Dart

Postby maurice northcott » October 2nd, 2015, 12:16 pm

Phil
The Revell one I remember was smaller then 1/48, probably "box scale" as was often the case back then :D , I am talking mid/late 1950's.
Cheers
maurice

Alan Cantwell 1131
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Re: Convair YF2Y-1 Sea Dart

Postby Alan Cantwell 1131 » October 2nd, 2015, 3:47 pm

Blimey, bit ambiteous Phil, I was looking over one of these at the florida air museum, at Lakeland airport, Florida, bit of a beast, you will have to find your own piccys, mine wont go small enough for here :?

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Re: Convair YF2Y-1 Sea Dart

Postby Alan Cantwell 1131 » October 2nd, 2015, 3:48 pm

mine wont upload, but heres an image from the museum,
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Alan Cantwell 1131
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Re: Convair YF2Y-1 Sea Dart

Postby Alan Cantwell 1131 » October 2nd, 2015, 3:50 pm

image.jpg
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Phil Clark
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Re: Convair YF2Y-1 Sea Dart

Postby Phil Clark » October 2nd, 2015, 8:56 pm

The research was complete enough to start making a decisions regarding the approach to the model.

Many scales were discussed and after weighing up all the options we enthusiastically went with 1/4 scale which makes the model over 4 meters (157 inches) in length and 2.5 meters (98 inches) in span.

Helped along with a suitable budget it was decided that the model’s scale fidelity be put before all other considerations. So everything from this point is done to achieve that goal regardless of the more traditional constraints to such a project. This is probably as far from a traditionally built model as one could get.

The models whole philosophy dictates a different approach to its creation. There are seven companies involved in it’s design and fabrication. All the companies are based here in the UK ranging from small businesses to multi million pound engineering firms.

The further along we get the more confident we become that this projects eventual success but there is still a risk over and above a regular scratch built project. With this in mind our approach to everything is with reproduction in mind.

Initially, two models will be built, the first a pure prototype whereby we can try our design ideas with the second used for the implementation of the designed solution. Both models will be built concurrently with the obvious need for a slight offset in build stages.

The project has been broken down in six distinct phases. Research, Pattern, Composites, Skis, Build and Testing.
Attachments
Dart_LMA_5.jpg
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Last edited by Phil Clark on October 2nd, 2015, 10:17 pm, edited 1 time in total.

Phil Clark
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Re: Convair YF2Y-1 Sea Dart

Postby Phil Clark » October 2nd, 2015, 9:06 pm

Although the budget allowed for a full CNC’d pattern the client was keen that this model has as much of the character as the original. Often very large models are impressive only due to their size but lack any real depth of character. By involving professional modellers in the production of the pattern, it's possible to build in the modellers touch, add every rivet (over 100,000), every panel line and every bowed or warped panel to create something very believable. This is all possible straight from CAD but it was decided the end result would be better achieve by doing the detail manually, after all... the original was built by hand so it was felt it would be fitting that the pattern also be hand built.

This decision was helped along with the fact that we still had some holes in the research and areas of the model would need to be done with reference to photos alone (no drawings were available of certain areas). An experienced team of professional modellers would have more success with this approach and have a sound understanding of whats required in a large complex model such as this. The SeaDart pattern is built purely by hand using scaled original drawings taken from the Convair Archives. All drawings were painstakingly digitally cleaned then enlarged to exactly 1/4 scale giving very good resolution and a decent start for making the pattern.
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Dart_LMA_7.jpg
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Phil Clark
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Re: Convair YF2Y-1 Sea Dart

Postby Phil Clark » October 2nd, 2015, 9:17 pm

And it was at this stage where we (Fighteraces) were commissioned to build & detail the Sea Dart patterns.

Following lengthy discussions with Alex Jones @ TLJC, it was with a great deal of enthusiasm that we agreed to take on the Sea Dart project earlier this year. We have produced a number of very larger piston engined model for other clients over the past 10 years, but the opportunity to work on a ground breaking project of this size and complexity was something we simply couldn’t turn down. Though this is a jet model as opposed to our normal piston engined models, we felt the experience we have gained over the past 10 years of offering our building services could be brought together on this project to deliver an accurate pattern with a very high level of exterior detail as specified by the client.

Initial CAD drawings were produced by Fighteraces for the wings and fin using the original aerofoil sections. Lift characteristics for the Sea Dart delta wing are not impressive. These are symmetrical airfoil sections with a mean aerodynamic thickness of only 3.83%. The L/D is low at high angles of attack. Long conversations with the client were had regarding this and in the spirit of the project it was decided to go for a completely scale wing with blended aerofoils from root to tip using NACA-003.30-65(Mod) and NACA-0004-65(Mod). The fin is very similar but uses NACA-0003.5-65(Mod) at the root. These are the exact aerofoils used on all five Sea Darts that were built. This is one of the very first supersonic delta wings designed and flown. Convair learnt a great deal from this and put this knowledge into some of their other iconic supersonic deltas. (Delta Dart, Delta Dagger, B-58 Hustler etc....)
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Phil Clark
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Re: Convair YF2Y-1 Sea Dart

Postby Phil Clark » October 2nd, 2015, 10:41 pm

Initial construction starts with the vertical tail fin. All ribs have jigging tabs which were tack glued to the bench to ensure perfect alignment before the 1st skin was added.

Appearing maybe over engineered for a tail fin, but being a master pattern for a composite mould, weight is unimportant with this project whereas the structural stability of the finished component is the key. All laser cut parts are from 1/4" birch ply and the skins are 2mm liteply.......the finished fin is HEAVY but immensely stiff so ensuring there is no distortion during the mould making process.

The double rib marks the joint on the top of the fuselage.......the lower section will sit on top of the wing inside the fuselage (with a wing section shaped packed on it’s root end). This internal section will be cut down in chord.......the front rib sections will be removed back to the front face of the front spar.....the rear to just behind the rear tube.

Three tubes are fitted, 10 mm at the front, 20 in the middle and 16 at the rear. These are purely for alignment & fitting purposes only. They are unlikely to be used on the final flying version simply because they do not pass far enough up into the fin due to the thin section. Double if not triple full section blade type spar/joiners are likely to be used on the flying model.

The shear spars are all cut approx. 2 mm under size & they are faced in balsa that is easily sanded flush to the ribs. The LE is a section of hard 1/8” balsa notched onto the ribs......this gives the skin something to bond to at the LE + a larger base for the hard balsa LE block to bond to.
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Dart_LMA_9.jpg
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Dart_LMA_10.jpg
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Dart_LMA_11.jpg
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Phil Clark
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Re: Convair YF2Y-1 Sea Dart

Postby Phil Clark » October 2nd, 2015, 10:43 pm

And to give an idea of scale......the fin will look tiny against the wings which have a root chord of almost exactly 8 feet.

Phil
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Alan Cantwell 1131
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Re: Convair YF2Y-1 Sea Dart

Postby Alan Cantwell 1131 » October 3rd, 2015, 6:31 am

Incredible Phil, you need to nclude some tickets to florida, go look at the sea dart there, purely for research, of coarse, should take about 2 weeks?

John Greenfield
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Re: Convair YF2Y-1 Sea Dart

Postby John Greenfield » October 3rd, 2015, 7:14 am

Hi Phil

Do I understand it that you will be making the patterns that will eventually be used by someone else to make a full composite model or are Fighteraces going to be involved all the way through to fitting out (and flying) the finished model (s) ?
John

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paul needham
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Re: Convair YF2Y-1 Sea Dart

Postby paul needham » October 3rd, 2015, 7:45 am

Interesting subject Phil, this may sound a daft question, will the finished model be flown off water as per the real one ?


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