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Member postings for Allan Bennett

Here is a list of all the postings Allan Bennett has made in our forums. Click on a thread name to jump to the thread.

Thread: How to smooth the glue lines between balsa sheeting?
10/05/2020 20:58:38
Posted by Steven Shaw on 09/05/2020 14:17:02:

Eze -Kote is made for glassing

https://www.youtube.com/watch?v=r_oZlHrdSpA

I see that Eze-Kote is in fact a resin, so maybe I could use my regular 2-part glassing resin as a wood hardener before sanding and glassing? I'll try that first on the nose section of my current build before it gets too much hanger-rash, prior to final finishing off with McG 6969's curved sanders, and then glassing.

Mike T, ensuring no glue anywhere near the surface is, for me, easier said than done. If my planks/strips are a nice close fit then whatever glue I use will wick up, or be squeezed up, to the surface. How do you prevent that? The best I can do (and do do) is to wipe off the surplus immediately.

Thread: Tony Nijhuis' new Vulcan
09/05/2020 20:21:46

The 2S setup is very tempting, as it looks like I can get more total mAh, and I've got more latitude for adjusting the c.of g., but I think I'll stick with 4S. In this picture the 2S mock-up is hard against the leading edge, but there's plenty of scope to move it backwards. I'm going to keep my motors paired as inners and outers.

20200509_143505.jpg

Here's a 4S 2900mAh hard up against the front spars. Obviously it's too thick to go between the spars like the 2S pack does, and it's too thick to move any further backwards because the wing thickness diminishes towards the trailing edge.

20200509_143524.jpg

Hopefully with a bit more web browsing I'll be able to find a 4S pack which makes a bit more use of the available space.

Thread: How to smooth the glue lines between balsa sheeting?
09/05/2020 12:44:30

Thanks for those quick replies. I'm not talking about blotches of dried glue that I should have wiped off when wet, but the actual glue that's between the planks is still a hard spot that I find makes finishing difficult. I've tried aliphatic in the past, and I don't recall it being any better than regular white glue in that respect. I might look at Gorilla white for the next build, though basically I find that any glue is harder than the balsa, so causes the ridges.

Maybe hardening up the balsa with 'sanding sealer' will help. But won't that (or Eze-Kote) add weight, and will it be detrimental to the glassing that I propose to do?

I like the idea of making curved sanding pads from cardboard, so I'll try it, thank you.

Thread: Tony Nijhuis' new Vulcan
09/05/2020 11:24:50

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.

Thread: How to smooth the glue lines between balsa sheeting?
09/05/2020 11:04:02

I'm at the stage now where I've structurally completed a traditional balsa model, but am having my usual problem of how to achieve a perfectly smooth round fuselage. Some parts of it have been planked with long sheets spanning several formers, and others with separate sheets between each former.

Anyway, my perenial problem at this stage is how to sand them down to a smooth finish. Whatever I do the glue lines, be it CA, white wood glue, or epoxy, always stand proud. My usual sequence is to sand (file?) them down with a flat Permagrit tool before then using finer sandpaper or sanding blocks to achieve a nice round finish. But invariably I can still feel ridges with my fingertips, so can anyone suggest a simple way to speed up my progress towards perfect roundness?

Thread: Tony Nijhuis' new Vulcan
08/05/2020 21:31:17

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.

08/05/2020 12:43:31

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.

08/05/2020 11:33:51

Thanks Neil, that's encouraging.

07/05/2020 21:52:39

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

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.

03/05/2020 19:56:14

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.

20200503_140458a.jpg

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.

20200503_140602.jpg

Thread: Glass fibre push rods advice
29/04/2020 20:56:42

I've had a couple of kits with balsa pushrods, and the connection method recommended was as you suggest, with the addition of the end of the clevis rod (metal, I presume) being bent at 90 degrees and inserted into a hole drilled through the balsa. For round rod I would file a slight flat on it for the length of your clevis rod overlap. That will help with drilling the hole, as well as keeping the clevis rod in place better while you bind it.

Thread: Tony Nijhuis' new Vulcan
29/04/2020 08:33:21

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.

28/04/2020 21:00:49

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.

Thread: Aerial orientation
23/04/2020 11:25:18

With all 2.4GHz receivers the two antennae should ideally be fixed at 90 degrees to each other, and away from any metal/wire or carbon fibre that might stop them getting a signal. The antenna itself is the silver bit of wire about 30mm long at the end, and they don't have to be adjacent to each other -- just 90 degrees different orientation. I usually attach pieces of plastic tubing to the fuselage to hold the antennae.

PPM is the normal signal used to control servos, but I can't help you with what those two terms mean on your particular receiver. If you post the make, someone should be able to answer that question and/or point you to a manual.

Thread: Source of connectors, 5 & 8 pin.
22/04/2020 08:04:32

I paint one side of the plug bright yellow so I get it right way up, and I try to arrange the pins so that plugging in wrong way round will not result in a reverse polarity situation.

21/04/2020 20:27:36

I use RS Components for the same kind of sockets as Martin McIntosh has mentioned -- they come in single or double row. I use standard PCB header pins for the other half of the connection. I usually make up a PCB for them so I can mount them in the fuselage, but you could also use Vero board or similar.

Thread: RAF Lettering Font
21/04/2020 20:19:56

Thanks PeterF. That's a different source than the one I used, so I've now downloaded, extracted, and installed the RAF file from there. It's the same one as I had before, as it prompted me that the font is already there, do I want to replace it. So I replaced it. In MS Word I still have to type something first using the default font, then highlight it and change it to the RAF font. But then I can add and/or edit the text and it retains the RAF font style, so that's progress.

It still doesn't work with Silhouette Studio, but at least I can do decals using word, and if I want to cut any vinyl or paint masks I can type what I want in Word, print it and then scan it into Silhouette.

21/04/2020 13:37:26

I'm having trouble getting the RAF_PW_ATH font to work: My PC uses up-to-date Windows 10, and I've downloaded the font, unzipped the files, right-clicked on the font file, and installed it. I can see it in the list of available fonts in the three programs I use most often -- MS Word, CorelDraw, and Silhouette Studio -- but it doesn't work properly in any of them.

In MS Word if I select the RAF font from the drop-down list, as soon as I start typing it reverts to Ariel. I can type first using the default font and then highlight it and select the RAF font from the list, and it then works, but if I edit or add to the text the new text is in Ariel.

In CorelDraw it shows up in the drop-down list of fonts but, if selected, does nothing when I start typing. In Silhouette Studio it reverts to Ariel font even though RAF_PW_ATH is selected in the drop-down list.

I'm wondering if perhaps I've installed a fake/clone/duff version of the font, so can someone give me a link to the version they used, please?

Thread: Tony Nijhuis' new Vulcan
20/04/2020 12:26:36

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 wink

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