Convair YF2Y-1 Sea Dart

[paul hughes]

Alex, the above computer image above is very impressive. Can i ask what program you are using for your 3d imaging, Thank and well done on this impressive project.

[Alex Jones]

Hi Paul,

Thanks... We use a number of different products depending on who we're working for. CAD wise Siemens NX and Keyshot enterprise for renders although we do use F360 and its inbuilt ray tracing on image representations for clients.

Cheers, Alex

[Alex Jones]

Thank you to FighterAces for all their hard work on the paint. Almost all the paintwork is now completed with just a few parts that need to be finished after the final installation. I can start completing some of the small installation jobs while I wait for the new elevon mechanism components, this really needs to be done before anything major goes in.

Paint_Complete by Alex Jones, on Flickr

[Timothy Huff]

Alex, will you be able to post videos of the initial trials once it's "finished? It's an extraordinary achievement.

[Alex Jones]

Hi Timothy,

Yes.. I'll post all the videos we take as we go.

Cheers, Alex

[Dave Kellett]

Hi Alex and happy new year to you and the team.
It's been a while since we have heard about any progress, are you any closer to completion?

Best regards

Dave

[Alex Jones]

Hi Dave,

Thanks.

Lots of progress and still on track to get it on the water in April. I have loads of photos I need to upload but haven't found the time as I need to get as much done in January as possible due to other commitments in February. I will update the thread in the next few weeks, sorry for the delay.

Happy New Year to everyone.

Cheers, Alex

[Dave Hayfield]

Large article in Aeroplane Magazine on the Sea dart February 2020 which may be of interest to you.

[Dave Kellett]

Hi Dave yes your right,
Very interesting, Would love to see the progress of this one tho
Build thread has gone very quiet. I hope everything is ok with it

[Alex Jones]

We're still here and the project is ready to have its first water runs next month although it looks like we will struggle to get the team together with the ongoing situation. At least I'll soon have plenty of time to update the thread... we will be ready to run the model when normality resumes. In the mean time I'll start getting this thread up to date.

Cheers

[Alex Jones]

It has been a while… sorry

I hope everyone has managed to stay safe and well during these last few months… strange times.

We have been busy working on multiple projects one of which is the SeaDart. We had planned to do the initial water tests in April but as it became clear this would not be possible we switched focus to other design work and projects that could be undertaken easily from home. I suspect we will be looking at the end of the summer before we can get the whole team together to begin testing. When we can the model is ready and waiting.

In the mean time I’ll start updating the thread. The last posts were at Fighteraces with them having just completed the paintwork.

Once delivered to me the first thing to do was install the new elevon mechanism that was designed while it was in paint to replace the previous iteration which wasn’t up to the task. The new system has two large servos per elevon mounted near the CG. The elevons are actuated via a carbon tube and large drive horn. The bearing block and elevon drive is shown below.

F434BC2F-7892-417C-B063-67D86F8BE44C by Alex Jones, on Flickr

4BF4E8BE-4016-4797-AB37-1E0B645FB01F by Alex Jones, on Flickr

Servo frame work that will be bonded into the fuselage near the CG.

F9DA4661-1BAD-406E-922E-AB07627FB067 by Alex Jones, on Flickr

8DFCA86F-156D-4ED1-B604-67626D7598BE by Alex Jones, on Flickr

We are having to move considerable torque through this system so everything gets tied into the existing structure.

[Timothy Huff]

I imagine one issue you may have to deal with, is what happens when a control-surface is hit by a lot of spray, or worse, "solid" water at some speed. Is there any protection of the servo's, ie a deliberate "weak-link" in the linkages between servo and control surface that'll withstand normal flight-loads, but not harm the servos or the control surfaces if it suffers a sudden load of this type?

Or is it "simply" designed to withstand such impacts? I'd be interested to read a bit about the design philosophy of this amazing project...

[Alex Jones]

Hi Timothy,

This is a concern but we believe that the design will cope, having said that... we obviously plan on testing the model on the water extensively before committing to flight. I'm really looking forward to the RC boat stage of the project!

With the rear elevon bearing block assembled I can now bond the elevon hinge supports in place. Both wings were bolted onto the fuselage. The elevon hinge supports installed in the elevon hanging off 2mm piano wire. These are bonded with Hysol into their slots in the wing. I then installed the bearing block structure using more Hysol and bolted the drive shaft to the elevon ensuring everything is in line while it cures.

F91A0C20-F869-4378-ABC3-84FB04007B6D by Alex Jones, on Flickr

E07CB5BF-A039-4878-A043-460550DA4B35 by Alex Jones, on Flickr

D317649C-72E0-4978-9CD4-B239F7275571 by Alex Jones, on Flickr

Now cured the main bearing blocks have been removed ready to paint the structure along with the servo frames situated about a meter forward of the bearing block structure.

BF045C0F-925D-4920-AD35-DB606B84DD57 by Alex Jones, on Flickr

[Timothy Huff]

That's bloody gorgeous, there's no other word for it. I love how clean and considered the whole design is - it shows none of the bodges and work-arounds my stuff tends to accrete!

[Alex Jones]

Thanks, although... I have plenty of work-arounds and areas that have been re-designed as they just didn't work. The elevon system is the third design iteration and if I needed to do another SeaDart at some stage I would change more but you only know by doing. Ideally I would like to build another one incorporating everything we have learnt from this prototype. I might struggle to persuade all involved! Worth a try though....

[Alex Jones]

This really should have been done before painting but I missed it along with a few other things. The corners are a little delicate and not supported as it's feathered carbon in these areas. If I don't reinforce it now it will no doubt get knocked at some point. I cut and bonded some carbon tube into the root trailing edges of fuselage and wing, I’ve only added this inboard of the first hinge as the elevon protects the rest.

634A61E9-4C03-4C08-8513-FCDDB3098861 by Alex Jones, on Flickr

This will be cleaned up with a light sanding. I will re-touch the paint at the end of the build as inevitably some other areas no matter how hard I try will get the odd scratch. May as well do it all at the same time…

The hinge supports.

1A51254C-5F6E-40F4-ABB0-83547F7330C0 by Alex Jones, on Flickr

[Alex Jones]

I hope everyone had a decent weekend.

With the support structure for the new elevon mechanism in place it was time to touch up the internal paintwork. I masked the entire fuselage section… just in case of any accidents!

DAEB7309-CDD0-45C2-8706-6A2482797382 by Alex Jones, on Flickr

I also reinforced the aft most former join with some carbon tape after filleting the angle and then applying with resin. (Before painting and while masked to avoid any resin fingerprints on the paintwork)

41FA6727-A310-4487-8D66-52070B589C9E by Alex Jones, on Flickr

[Alex Jones]

With the internal painting completed I can finally get on with installing things for the last time. The rear elevon mechanism which includes the bearing blocks and actuating arm. The arm is installed with 6 capstan bolts to aid locking. I add shrink sleeve to the wire locks to avoid cutting my hands to shreds every time I need to get into the hull for the installation. I learnt the hard way!

BAE9A88E-3494-4F7B-87CB-07E9ECB97B01 by Alex Jones, on Flickr

The connection between the servos and rear mechanism is achieved with a 12mm carbon tube, aluminium inserts bonded and bolted in place with a left hand threaded M8 rod end.

A2C6BDAC-D9C3-4D52-BBF6-9F2A7EDB85A5 by Alex Jones, on Flickr

[Alex Jones]

On the servo side of things we decided to try the large Seiko servos, loads of torque but a little slow. They have a tie bar with a slot, this allows any disparity between the servo matching without loading the servo because they are fighting each other. It also allows movement of the elevon with one servo failed. This at least gives you a fighting chance depending on where in its travel it fails… a difficult situation but better than no control at all!

2ADBDE86-5AC5-438A-AF80-9F42D0618494-2 by Alex Jones, on Flickr

C8E443E8-328F-4C2B-80D9-B2B7CC3C8BFA-2 by Alex Jones, on Flickr

I have also designed a bolt on tray so we can try some other servos and decide what is best.

936BC4C8-6F9D-4952-AD55-F011F3E55A02-3 by Alex Jones, on Flickr

[Timothy Huff]

Alex,

How will this be manoeuvred from trailer or vehicle to the water normally? I imagine during testing it'll be a case of all concerned playing "rock-paper-scissors" until one poor sod takes their shoes and socks off to go paddling with the front end!

With the skis, I imagine it's not the easiest thing to get from dry-land to the water and vice versa? P'raps we could have a competition for a means to avoid Phil taking his socks off?