Tony Nijhuis' new Vulcan

[Allan Bennett]

Thanks John, 240 or 250 it will be then. I didn't realise laminating film came in different thicknesses, other than what seemed to be a logical assumption that bigger sizes would be thicker.

[Neil Hodson 2]

Hi Allen

I used cardboard for the tubes. Seal with mastic before taping up. Much lighter, I used silver cardboard from a craft shop to save painting the ends where they project from the rear. I would post a picture but cant remember how to add an album.

Neil

[Allan Bennett]

Thanks Neil Hodson 2. Laminating film is on its way, and I don't have any large enough sheets of anything else, so I think I'll stick with it.

[Martin McIntosh]

I had the same problem on my small Vulcan. I could not get the recommended thickness locally so settled for some thinner stuff which was a nightmare to fit.

On another build I tried 250 micron acetate but this had a mind of its own and I found that thin card was very much easier to work with so have used this on my other EDF models.

[Allan Bennett]

250 micron laminating film arrived today and, judging by what a PITA it is, I'm glad I didn't go for the lighter recommended 150 micron stuff. I can see that thin card would be much easier to work with, but I've now got four film tubes ready to final-fit.

[Allan Bennett]

Slight snag today

Working slightly out of sequence I decided to install the skinning between F5 and F6. At the same time I checked the fit of the nose retract, and it didn't. First thing was the hole in F6 was slightly too small for the retract motor to protrude through so, with a little bit of help from a small round Permagrit, it was opened up. I could then seat the retract unit in its mounting blocks, but the u/c wheel still fouled the rear end of the well by about 1/4". For once, it wasn't my measuring and building at fault, for I'm using TN's plan pack, and all the pieces in that area simply slot together prior to gluing.

In the end I had to cut a larger opening in F6 so that the whole of the retract assembly could poke through, as you can see in this photo. I added a couple of bits of reinforcement where I'd had to remove some wood at the F6/S3 junction. Having read through this thread completely a couple of times, I don't recall seeing this problem before, so I wonder if the spec of the TN-supplied retract unit has changed since early days.

[John Neale]

Shouldn't think the retract unit has changed Allan. I used the HK units which seem to be the same as yours but I do recall creating more space at the wheel end. I also had to modify the area around the nose wheel steering linkage to ensure it didn't foul up during retraction. You reinforcement seems perfectly adequate. Keep going!

[Allan Bennett]

Yes, I remember reading the bit about clearance for the steering linkage in one of the old posts. I've never used a steerable retractable nosewheel before, but the linkage seems to have enough clearance at the moment. I'll have to pay close attention to that as I progress. From a structural point of view I'm not sure if my reinforcement is really necessary, for there's no stress on the nose section unless it hits the ground

[Martian]

better to be safe than sorry at least no real weight penalty ..lovely build

[Allan Bennett]

Just finished the power wiring for the fans and ESCs today. I'm using four Jeti Opto 40A ESCs, and a test run of one fan gave me about 37A on a 4S 3300mAh pack at storage voltage. Getting the ESCs in wasn't too much of a problem, but the wiring will need to be tied down to stop it banging the thrust tubes. I've added extra capacitors to the innermost ESCs, as their battery leads will be longer than usual.

But this evening I've been scanning this thread again to find where you've placed your receivers. On the central spine (W1?) seems likely, though it's a bit closer to the two inner ESCs than I would normally like. I suppose 2.4GHz doesn't really care that much.

[Craig Carr]

Hello Allan,

My rx is just in amongst all the wiring of the centre spine. I just fixed it onto a servo pad.  If you zoom in and look towards the rear you may just see the word “futaba”

have had no interference issues whatsoever (using Futaba 2.4 FASST). Obviously do a range check before first flight to be sure

 

Edited By Craig Carr on 12/02/2020 15:23:44

Edited By Craig Carr on 12/02/2020 15:25:32

 

Edited By Craig Carr on 29/04/2020 07:59:43

[Allan Bennett]

Thanks Craig. That's the image I saw earlier that made me think it was in the spine and, now that you mention it, with enlargement I can just see it nestling beneath the cross member at the rear.

I used to fly Futaba, but a couple of years ago I sold up and converted to FrSky. Unfortunately their receivers are a bit bigger than the Futaba equivalents, but connections are on the end instead of on top, so it will fit.

[Allan Bennett]

Ok, my receiver fits nicely in the position shown in this photo. I'm using a FrSky stablised receiver, so it needs to be attached firmly using sticky-backed foam, hence the infill piece in the cutout in the spine.

Since I'm using opto ESCs (because that's what I had in my bits box) I need a couple of stand-alone BECs, one for the radio gear and another for the retracts. They fit nicely in the main gear wheel wells, where they are reasonably accessible if needs be.

[Allan Bennett]

Posted by Daithi O Buitigh on 13/02/2020 11:20:45:

Posted by Martin McIntosh on 13/02/2020 09:34:54:

You will not require 4s. Beside the flight time being less you will have trouble squeezing the packs into the already very limited space.

Don't forget, Martin that there are TWO FMS units - the 3S and the 4S. The 4S version running on 3S has LESS thrust than the 3S version running on the same set-up.

From the thrust quoted by Allan, he has the 4S versions

I've got far enough with the build (full-length intake duct liners installed, and thrust tubes anchored at each end) that I was able to check the thrust today, nose-down on my scales: I'm using the 4S FMS fan units with two 4S 3300mAh Turnigy 20-30C LiPos which, for this test, were at 3.85v each. Total thrust was 1.65kg -- certainly nowhere near the quoted values, as was said in another post, but adequate so long as I can keep the weight down.

[Martin McIntosh]

Don`t quite get it . Were the packs in the model and everything enclosed as per for flight? I had to squeeze in my two Zippy Compact 3300 3s ones so how do you fit 4s in? Power on 3s was not an issue from tarmac but not so from our grass strip. I started to replace the fan blades with a higher blade count but it has not got very far. Speaking to TN he said to scrap the original HK ones and replace with FMS but this would be difficult and very expensive so it is on hold.

[Allan Bennett]

No, the packs weren't in the model -- the wings aren't on it yet! The batteries are ones I have for another model, but I have offered them up to the battery bays, and they look like they'll fit (just) with the leads facing forwards through a large hole in the shear webbing. However I'm reconciled to the fact that fiddling them in may in practice be too much hassle, and I'll have to find something slightly smaller. My particular 3300mAh Turnigy pack is no longer listed but, looking at the published specs, Zippy Compacts at around 3000mAh seem to be significantly shorter and slightly thinner. A very thin hatch cover, maybe 1/64" ply, surface mounted rather than flush, will also help if shove comes to push.

In fact, thinking aloud now, maybe I should do away with the 2.5mm balsa sheet that's in there as the base (i.e. top) of the battery bay, and instead simply apply a layer of fibreglass to the inner surface of the wing skin and up the sides of the two ribs that form the battery bay. That would give me an extra couple of mm of depth in the bay.

Edited By Allan Bennett on 07/05/2020 21:53:22

[Neil Hodson 2]

Posted by Allan Bennett on 07/05/2020 20:22:37:

Posted by Daithi O Buitigh on 13/02/2020 11:20:45:

Posted by Martin McIntosh on 13/02/2020 09:34:54:

You will not require 4s. Beside the flight time being less you will have trouble squeezing the packs into the already very limited space.

Don't forget, Martin that there are TWO FMS units - the 3S and the 4S. The 4S version running on 3S has LESS thrust than the 3S version running on the same set-up.

From the thrust quoted by Allan, he has the 4S versions

I've got far enough with the build (full-length intake duct liners installed, and thrust tubes anchored at each end) that I was able to check the thrust today, nose-down on my scales: I'm using the 4S FMS fan units with two 4S 3300mAh Turnigy 20-30C LiPos which, for this test, were at 3.85v each. Total thrust was 1.65kg -- certainly nowhere near the quoted values, as was said in another post, but adequate so long as I can keep the weight down.

Hi Allan

I got 1.5 kg thrust using the same test (this was with Dr Mad Thrust units) so you should be OK.

Neil

[Allan Bennett]

Thanks Neil, that's encouraging.

[George P.]

Posted by Allan Bennett on 07/05/2020 20:22:37:

Posted by Daithi O Buitigh on 13/02/2020 11:20:45:

Posted by Martin McIntosh on 13/02/2020 09:34:54:

You will not require 4s. Beside the flight time being less you will have trouble squeezing the packs into the already very limited space.

Don't forget, Martin that there are TWO FMS units - the 3S and the 4S. The 4S version running on 3S has LESS thrust than the 3S version running on the same set-up.

From the thrust quoted by Allan, he has the 4S versions

I've got far enough with the build (full-length intake duct liners installed, and thrust tubes anchored at each end) that I was able to check the thrust today, nose-down on my scales: I'm using the 4S FMS fan units with two 4S 3300mAh Turnigy 20-30C LiPos which, for this test, were at 3.85v each. Total thrust was 1.65kg -- certainly nowhere near the quoted values, as was said in another post, but adequate so long as I can keep the weight down.

I have always understood that the lipos need to be fully charged to get an accurate reading of the watts or thrust? Could be why the values are down?

[Allan Bennett]

George P, yes I'm expecting higher readings with fully-charged LiPos, but I just wanted to get a ball-park figure with my LiPos which were already at storage charge while we're not flying. I don't expect anything like the manufacturer's published figures, but another 10% or so would be nice.

[Martin McIntosh]

Even with the Zippy Compact 3s packs I had to wrap strong thread with a pull loop round one end to prise them from the Velcro. The covers are very thin too.

[Allan Bennett]

You're right! My impression that it would fit was before I had any sheeting on the wing. Now that I've sheeted the underside, and cut out the rectangular battery opening, it's quite clear it won't fit. Even if I make the opening a trapezoid, right to the spars, it probably won't work.

The rectangular opening is 125mm long and, on checking the HK site tonight, I find that most of their 4S (and 3S) packs around 3000mAh are about 137mm long. There's one at 111 mm long, but it's too thick to fit between upper and lower wing sheeting.

In the past when I've been short of space I've gone for Thunder Power Prolite packs, and they've got a 4S 2800mAh pack that's only 101mm long and will just fit between upper and lower sheeting if I remove the 2.5mm balsa battery support plate. I'll shop around further before I buy, but at least I know there's a solution without having to resort to butchery.

Another possibility I've been thinking of is to use two 2S 6000mAh (or more) packs, one each side, connected in series to make single 4S 6000mAh. The advantage would be that they'll be thin enough to slide between the upper and lower spars front and back. Looks like this Nano-Tech 6000mah pack would fit in that manner.

[Martin McIntosh]

I too thought about the 2x 2s route. The problem there is that the battery to esc wiring would be rather long which esc`c do not like.

I would not touch another Nanotech with a barge pole. All the ones I bought puffed after a single use and I know that I am not alone on that count.

[Allan Bennett]

Another issue I've thought about the 2 x 2S route is that the cables will be carrying the total amps load of all four ESCs, so heavier wire would be needed. I'd initially settled on the two inners connected to one battery and the two outers to another, so have already added extra capacitors to the ESCs that connect to the 'opposite' battery. I can add more if I go the 2 x 2 route.

I'd also heard elsewhere what you've said about Nanotech, so will be avoiding them. Since I posted last night I've looked at the Overlander site, and they seem to have several 2S or 4S that will do the job. This one looks like it will fit, so I'm going to mock it up in balsa this afternoon and see how it goes. There's also another 2700mAh one which will definitely fit, and plenty of long thin 2S ones. More pricey than HK though.

[Craig Carr]

I went the 3s route (although mad thrust 10 blade). I could only just get this turnigy 3s 3000mah in.... literally “just”. Pushed all the way to the leading edge for balance