Alex48

Thank Lavi, fingers crossed.

I started the main installation by removing everything from the engine test stand and installing this into place inside the fuselage. I used new Festo 6mm tubing but other than that everything is exactly as it was on the stand. All the associated turbine wiring was run through the fuselage. In the CAD images above you can see the carbon tubes that tie the formers together, these are 18mm tubes and also act as conduits for the wiring. Before going to the effort of making everything neat the turbine electronics were all tested to ensure everything worked as expected. I have two Digitech CTU’s on each turbine which have already proved to be very useful.

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It’s then just a matter of running all the other wires, this took some time….

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lavi rider

My Feedback: (6)

How many actuators are you running it? Isn’t it advisable to have shielded wires to the electrical components as I noticed there’s lots and lots of them in that tight space , to eliminate EMI potential ?

I also noticed the turbines are are not fully ducted , or are they and this is just a beta install test ..?

lavi rider

My Feedback: (6)

Yet, very , very impressive project !!!
Thx for sharing

Alex48

Hi Lavi, thanks

The turbines are fully ducted and will allow water to flow through the duct system without entering the fuselage as the various sections are sealed with o-rings. The above pictures are just a hook up and test of the electronics before I make things neat. On other similar sized models I've built I haven't experienced any EMI problems, I try where possible to group the wire runs to minimise this and separate power cables to servo runs, telemetry etc... Unlike other models this will have hours of testing on the water before committing to flight so does give us plenty of time to rectify any issues that arise... I'm sure there will be some.

Cheers, Alex

Alex48

With all the electrics in the aft section tested and working as planned I can make things a little neater. In the electronics box just forward of the hoist point we have a Jeti REX7A receiver, after burner light ring control, hull lights control and battery to power these lights. Ignore how the antennas are placed as these will eventually be correctly polarised and poke outside the box. Further aft (not pictured) we have a Jet RSAT 900 with the antennas placed on either side of the hull.

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The turbine electronics have their own individual boxes with the ECU and CTU inside. The Deans connection is just temporary and I will be replacing these with IC5 connectors which are more suitable for anything with the possibility of getting wet. They have proved to be excellent on my Son’s RC cars.

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One last test of all the electronics and peumatics before I split the fuselage to work on the electrical connection splits. There are twenty cables running through to the front which need to be easy to connect, secure and splash proof.

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Alex48

With the fuselage split I can get on with what seems to be a never ending list of jobs for the back end. Starting with the auxiliary air intakes. These are prototypical in that they do feed into the main intake. They remain open until the aircraft is >15kts and >60% thrust, when these conditions are met they close. These aren’t required from an operational point of view so are purely a scale feature although a little extra intake area won’t hurt. We expect this model to be relatively slow in the water at high power settings until the skis un-port and then get up onto the plane. We will play around with the close settings so it looks nice and scale during the takeoff run.

The intakes are constructed from various 3d printed components using SLA and SLS printing along with carbon hinges and actuators connected to some small MKS servos mounted at the top of the housing.

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A video showing their operation during a dry fit before we had the model painted.

Halcyon66

Nothing short of a masterpiece.

Outstanding.

Regards,

Alex48

Thanks, its getting there...

The intakes have been causing me a headache as they are very difficult to remove. They also require the turbines to be removed which very quickly got on my nerves. During the build these need to be installed and removed frequently which wasn’t time efficient and more importantly I need to push forward the intake just in-front of the turbine to get the vertical stabiliser bolt in place. With all this in mind I decided to split the intake again over the tank hatch. This allows me to easily remove the intakes and easily maintain the fuel tanks and ski actuators without spending hours removing all the intake system.

I made some 3D printed intake rings with a seal grove and split the forward intake as shown.

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Now its just a matter of removing these bolts on this section and I can access everything I need quickly. While at the lake I only have to do one side to facilitate the installation of the vertical stabiliser which speeds things up dramatically.

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Alex48

The tail wheel on the SeaDart was a castor so it could be easily manoeuvred by ground crew while on its beaching gear. I decided to make a fixed version as this could be easily integrated into the structure. The beaching gear wheels are located forward of the CG so it does have to takes its fair share of the load.



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3mm carbon was used to tie the wheel into the keel beam.



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Slotted over this carbon structure is a carbon composite pre-preg fairing bonded in place.



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The wheel is Aluminium with a 3D printed tyre running on a Stainless Steel shaft on Phosphor Bronze bushings. On top of this we made 3D printed fairing that simulates the look of the castor fairing.



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With a working tailwheel we can have the aircraft on the scale beaching gear and in theory it can move down a slip way into the water under its own power. Like the real one there will need to be a rope attached to the beaching gear so it can enter the water at a sensible speed.

ravill

My Feedback: (11)

Wow, just wow!

Amazing!

Alex48

Thanks I just hope it will fly! Im certain we can make a great looking static model, happy we can get it working as an RC boat, reasonable sure it will be OK as a hydra-ski, but the flying part is a bit scary to think about!

Following the theme of splash proofing anything electrical I have used high capacity RC car batteries in this case Overlander 7.4v 2S 5300 Lipos. These have worked well on our ARRMA cars which get drenched so should cope with this type of use well.

They are held in with a 3D printed latch, you just squeeze the red parts into the battery and it releases.



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I’ve mentioned before we are using CTU’s from Digitech and the twin turbine dashboards works well. To make use of the fuel telemetry the pump factor needs to be calibrated. After running fuel through each pump I then adjust the pump factor so the fuel remaining reads zero as the main tank starts to empty.



A short video shows the result… The pump factor settings are found in the CTU menu.






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I normally only fill the fuel systems on my jets at a rate equivalent to full thrust, It can no doubt cope with more but this way I’m sure I won’t over pressure the tank.



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While Ive been working on this I have come up with a plan and designed some components that will allow us to assemble the fuselage halves and join the electrics easily and seal them from any water. The start of the process below.



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tassos p

Looooll we all wish to see her in the air soon. What an amazing project and can't wait for your 105 as well.

Just a suggestion on the 2S for the P300s. I've stopped using 2S on JCs about 6-7 years back and sleep with a peace of mind. 2S are more prone to static discharges and possible flameouts. I now use 3S (Life or LiPo) on all my JCs, including my P300. In fact on my P300 I use 3s LiPo. Not sure if your ECU allows it to change the battery chemistry, I think it should. Static build up is always a problem if you take off from a hard surface but can also happen in the air especially with long plumping. Of course antistatic additive is a must but still a risk as the additive fades out after a month of fuel storage....

Maybe from water there's no way to build up static not sure of the physics behind that.

Tassos

Dave Wilshere

Tassos

I use nothing but 2 Li-Po in all my JetCat’s and never have an issue.
We don’t have your heat on tarmac issues...

Dave

ravill

My Feedback: (11)

Yeah, and that dry desert air is more likely to not let static discharge on its own. Water has that dipole charge leading to van derwal forces and hence the ability to ameliorate static charge.

tassos p

Hey Dave,

Yes for sure on V6 you can't use anything more than 2S (hence V6 was more prone to static) but on V10 ECUs you have a choice, hence my recommendation/suggestion, not mandatory. The logic is simple, the higher the input voltage the less likely you get static.

Thanks, Tassos

Dave Wilshere

Yes, I use 2s on V6. V10 and V12 ECU... and only V12 really is capable of dealing perfectly with 3s Li-Po, but it still has to take this down to operating voltages, so lots more heat in the ECU getting rid of the extra volts...
Anyway, back to Sea Dart...

Alex48

Hi Tassos,

Thanks… We're really excited about our 105 especially with the scale going to 1/5th after all our wind tunnel testing We have two large projects we are working flat out to finish then we can get back onto the 105 design, hopefully in November and get a prototype flown next year. Here is sneak peak at the 1/5th scale F105, this is just a CAD render of the design but should give some scale and this incorporates our new wing design. I'll start a thread on it later in the year once we're done with the SeaDart and our other commitments.

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Sorry, I digress... back to the SeaDart.

I have had clients experience static issues but none that have been based in Northern Europe, Interesting that the problems ceased when using 3S. It’s certainly something to bear in mind… are you using anti static tubing on the fuel lines also? Hopefully we won’t have any issues but I do have some 3S that I can try if we do. Lots of testing on the water before the flying part so hopefully any issues can be seen and rectified in this phase of testing, fingers crossed.



Like the 3D printed splash proof boxes for the electronics I decided to go a similar route with the fuselage electrical split. I designed two 3D printed housings either side where I am able to push the female PowerBox servo connector into the housing for an engineered fit. These housings are SLS printed nylon which are then tumbled and died black.



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The rear section layout finished and tested.



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This moves us onto the forward section which has 3D printed housings that slide and seal into the aft section housing thereby protecting the connections. To allow room to connect the wires I have around 200mm of excess cable which slides back into the long forward housing as the two halves are joined.



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tassos p

Hi Alex,

Looking forward (eagerly) for the 105 as I guess many others here.

I've actually had all my static issues while in Europe, but when relocated to Dubai 8 years back I've not had it again but this was about the time that I also shifted to 3S ECU source. But there are still a few people that flew JCs here in Dubai that got flameouts from static and all with 2S.

No I don't use antistatic tubing, I just use 3S batteries and antistatic additive in the fuel.

After many discussions with Jetcat themselves they strongly recommend 3S. In all the new P300s they've got it as a compulsory requirement in their manual (since 2018). Here's a snapshot from the manual:




But again, as Dave says, you guys know best, don't want to drag you down to it . This was just my suggestion and if I were building this bird I'd use 3S.

Looking forward for the completion of this project.

Thanks, Tassos

Alex48

Hi Tassos,



Thanks, if there is one thing that I have learnt in my career in aviation is that you should never assume you know best! The day you think you know it all is the day that you end up as smoking hole in the ground and I’ve always taken this philosophy forward into my RC businesses as well. It’s one of the reasons it’s good to share these builds as we get input like this. I hadn’t realised JC recommend only 3S on their new 300Pro.





The electrics in the forward section are run through 3D printed conduits that feed into the main box where the CB400 is mounted. There is another box on the bottom about 25mm deep that allows any excess wire to sit in, the bottom is capped with 2mm acrylic.



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I ran all the appropriate cables to the fuselage split ready to test each one individually, as mentioned earlier these are plugged in and the excess wire moves into the housing as the fuselage halves come together.



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Everything was connected up and tested for the first time with all 24 channels needed. We have a second transmitter that controls the pilots head, canopy actuation and locking so it has 30 channels in total.



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Viper1GJ

My Feedback: (20)

Great idea for mounting the RC switch Rx on top of the CB400. I'll steal that idea for future use. Thanks.
Gary

Alex48

No worries Gary



I’ve been putting off doing the Pitot for ages as it was one of those jobs that had the potential to cause some damage if I got it wrong. I started by making a hole in the top of the vertical stabiliser which had to be exactly in line and 35mm deep to allow the pitot to have a snug push fit into the stabiliser. This took me a long time!



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Once complete I used aluminium tube which will form the base structure of the probe. With the whole made (Phew!) and a straight cut along the stabiliser to mount the probe I traced the outline scanned this into CAD and started making a the fairing. This was printed using SLA allowing me to get a nice finish on the component. A Jeti Pitot is mounted in the end and everything bonded together and painted I now have a push working scale Pitot. If you don’t make these things removable they won’t last 5 minutes before being broken off.



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Just the end to paint silver to complete the scale look and being removable it stands less chance of being broken off.

mr_matt

My Feedback: (10)

Very cool, did you think about flying it in primer before adding so many details, paint etc?

kevinthoele

My Feedback: (1)

This has been an extraordinary project to watch take shape. I look forward to seeing to conclusion. Great work!!!!!!!!!

Alex48

Thanks guys, We did consider just testing in primer although much of the work is in the surface prep and primer so it wasn't a huge leap to then paint. It's also a relatively high risk project so to see the model in all its glory doing the surface testing is worth the extra effort

Moving onto the beaching gear… This will be really important for us and was designed in partnership with PES Performance Ltd. This can work as a stand allowing us to test the oleo extensions/retraction retract the skis and run the engines while safely sat on the beaching gear. Then can be wheeled down a slipway into the water. It has hydraulic brakes when in the full 5 wheel version or get broken down to the scale beaching gear the full-size had. The two versions can be seen in these computer renders.



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With the designs and drawings complete it’s just a matter of machining the components. These are all ready for hard anodising… (bar the SS stuff)



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Alex48

Just some images of the beaching gear coming together.



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