Phantom V3 - DLG - Design Build

[bracesport]

if you use wire pull strings there is no stretch - you can use braided fishing wire and there is next to no stretch with them - you may also be able to get kevlar fishing line - we use springs in the tail surfaces and a a pull line - there is no maintenance required.

I've been thinking of designs using pull strings. What do you do to account for the changes in length as a function of stretch or even CTE? I've seen some of the both positive and negative CTE on some of the strings... nylon, monofilament, PE braided line, Dyneema, polyester, etc. Do you re-tie every flight day or have something that will give, like springs?

 

[bracesport]

I am planning some 3D prints for the wing, servos, and motor battery - if I go with 4 servos in the fuse I will need two trays, one for the servos and one for the battery.

 

[otto54]

I am planning some 3D prints for the wing, servos, and motor battery - if I go with 4 servos in the fuse I will need two trays, one for the servos and one for the battery.

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What CAD software do you use?, I use Fusion 360 But is so much slow to design something good
It´s a very good project, congrats from Argentina

 

[otto54]

I am building a electric glider with a good balsa wing that i have, the fuselage disapears in a crash,thats why i am going to build something similar to the Marko Roolaid electric glider, but with a ruber type of atachment.
Sorry for my english

 

[bracesport]

I have done some fine tuning of the 3D printed parts for mounting all the internal components (assuming I run with four in the fuse) - there will be three lugs mounted into the fuse that the servo and battery trays will fasten to - this will allow me to build up the servo tray and slide it into position - I am also going to print some pull string pulleys to fit over the servo arms.

 

[bracesport]

I use ONSHAPE - it is a cloud based system similar to Solidworks!

What CAD software do you use?, I use Fusion 360 But is so much slow to design something good. It´s a very good project, congrats from Argentina

 

[bracesport]

This is such a slim fuse I am very sure it will be extremely tricking to fit everything in - I made a start on the wing mounts - as you can see I used a jig for the holes and 'touchwood' they look to be well aligned - even with the hole in the wing saddle access is tight as it is only one of my chubby fingers wide - the wing mounting bosses are on the printer now.

 

[bracesport]

I am liking the new printer - throughly recommend the 'Artillery Sidewinder X2' - the small mounting parts printed really well - each mount has a unique notch to indicate their location and mounting orientation - the 3mm nuts are glued in and they dry fitted into place nicely - very happy!

 

[bracesport]

There is a bit of work to do on the wing saddle as it was designed for my version of the synergy wing and I am using my BAMF poly'd wing - it is close so it should all work out OK - adding the V tail really changes things as I am so used to the DLG T tail these days - I have a reasonably long boom and a medium length nose so it is a bit tail heavy in the dry fit at the moment - I will bring the scales in next time and review the AUW with some hardware plonked inside.

Nevertheless it is pretty cool so far!

 

[Inq]

@bracesport,

I was just surfing YouTube and someone did a video to see how large they could do and keep under the 250 mg legal weight limit for drones. Purely a self-challenge of his.

I did not watch every second of his vid as he had to have some side topic of his wife getting pilot lessons. But he tried for 120", but had to scale back as that was too heavy. Most of your build techniques are superior to his. Are you also trying to keep under this 250 mg limit? Either way... with your experience, how large do you think you could go and still have a powered drone?

 

[bracesport]

I have seen this video - with RE it is easier to build light - 1.5 F5K gliders are probably sitting around 250g with 4 servos - 2.0m is probably a good size - I am not going to be under 250g with this build probably +300g.

 

[bracesport]

Here is some data for the weights as they stand at the moment.

If I completed this build as a DLG (four servos, battery, Rx) is is weighing the same as my BAMFzilla used to weigh at around 270g - so adding the motor, two more servos, and another battery (six servos, motor, ESC, 2 batteries, Rx) it is weighing 340g.

my fuse is 68g and tails are 22g at the moment - the fuse and tails will get some cleanup so there will be some weight removed in sanding, but adding pull strings and such might negate any savings - a factory made fuse is about 40g and the tail end is lighter.

In conclusion I think I will be targeting to get under 350g - I could save on two servos and a battery but with the big tail removing these parts might require additional ballast anyway!

 

[bracesport]

After some research and some thinking I realised that I have an excessively generous boom length for the V tail - my total fuse runs at about 1020mm and so I am doing surgery to shorten it to around 900mm - with nose length of 200mm and a speedster wing chord of 150mm I still have 450mm to the LE of the V tail and total moment arm of 550mm including the V tail - it will also help me with the balancing of the CG.

I will glue the tail mount into the boom as the taper allows me to sleeve them together.

 

[bracesport]

The fuse is rejoined again - glued and external filler applied - now we wait!

 

[bracesport]

The tail end of the shortened boom is cured and I did a preliminary sand - as you can see the weight dropped 5g to 60g - originally before shortening it was 68g.

When I moulded the fuse into the 3D printed parts I did not sand the moulds smooth - instead I put in a layer of 50g FG before the carbon - I am essential going to sand away the FG back to carbon making it smooth in the process - I did uncover a section of the boom that did not join correctly (small void) so I will fix that before sanding some more.

 

[Inq]

I wonder if I could impose on your experience with powering your glider. I went through your thread and found the 1507 motor, 20A ESC and 350 mAh battery.

1. Is that a special motor for gliders to swing a bigger prop? Most everything in that size class seems to be for racing drones and are spinning 14000+ KV and 2" props.
2. How big is your prop?
3. In that test you used two batteries. Is that the way you'll fly it?
4. What kind of runtime/climb can you get before you have to quit powering and be soaring?

Thanks.

 

[bracesport]

More recently I have been building and flying DLGs (non powered) - I decided to build a powered version as this is becoming a new class for the 1.5m ships - there are many options for the motors so I bought 2 - a 1507 and an 1806 - the 1507 is smaller in diameter and the 1806 will have a bit more grunt.

I am running either a 6.4 or 7x3 prop on the 1507 with the 20A esc on the 2C 350 - my second battery will run the servos and Rx so if the motor battery dies it will still fly as a glider - I used the 1507 as my fuse is very small - the 1507 is used in this class of glider by some of the factory made gliders.

I wonder if I could impose on your experience with powering your glider. I went through your thread and found the 1507 motor, 20A ESC and 350 mAh battery.

1. Is that a special motor for gliders to swing a bigger prop? Most everything in that size class seems to be for racing drones and are spinning 14000+ KV and 2" props.
2. How big is your prop?
3. In that test you used two batteries. Is that the way you'll fly it?
4. What kind of runtime/climb can you get before you have to quit powering and be soaring?

Thanks.

 

[bracesport]

In the meantime I am printing a new motor mount to fit the nose better allowing for the actual moulded thickness of the wall section - the Artillery Sidewinder X2 does a great job.

 

[bracesport]

I finally assembled the motor mount into the fuse - currently I have a 6x4 prop on the spinner (also have a 6.5x4 and 7.5x4.5) - I think I can extend the spinner cover (orange) back another 0.6mm to close up the gap to the fuse - otherwise it all fits well.

I have filled the voids where the seam failed to form when joining the mould halves - so far I have sanded 10g from the fuse and I will continue to tickle it up - I need to paint the nose and give it all a clear coat.

Next is fitting the tail properly and scratching my head on the servo placement.

 

[bracesport]

Starting on the servo mounts - the idea is to have a removable tray which the servos are attached to - I did a demo print and will tweak a couple of the dimensions for a better servo fit - also here is the CAD for the system as planned - there is a heal that is glued into the fuse that the servo tray dovetails onto - then there is a head that is also glued into the fuse that front end of the servo tray screws onto - it should all become clear if I can get the serve tray into the fuse though the canopy hatch!