Ballerina sans Tutu!

[Andy48]

While I would hate to throw a spanner into BEBs excellent calculations, there does appear to be one thing missing. BEB has not made any allowance for the IC flight battery. This is not marked on the plan nor is there any mention of it in the description. The flight battery is quite a heavy lump and if it was installed under the fuel tank this will make a difference to the CofG calculations.

[kc]

I knew there was some unknown factor!

Of course it could be that BEB intends to use a separate nicad for the Rx.

[john stones 1 - Moderator]

Hence the wiggle room lads, they'll be right...all of em.

John

[Biggles' Elder Brother - Moderator]

Posted by Andy48 on 10/01/2016 17:56:33:

While I would hate to throw a spanner into BEBs excellent calculations, there does appear to be one thing missing. BEB has not made any allowance for the IC flight battery. This is not marked on the plan nor is there any mention of it in the description. The flight battery is quite a heavy lump and if it was installed under the fuel tank this will make a difference to the CofG calculations.

No,....I haven't forgotten it, I'm not intending on using one! I'll use the BEC on the ESC and power the Rx and servos off the main battery.

BEB

[Andy48]

...but ...but ...but. I'd assumed you would use a BEC, however, Peter will have used a RX battery, probably under the fuel tank, and your calculations should have allowed for the possibility of that weight affecting the C of G on the original model as well as the motor and fuel tank.

Edited By Andy48 on 10/01/2016 20:47:36

[Biggles' Elder Brother - Moderator]

Sometimes the best laid plans of mice, men and aeromodellers (if a recidivist MR flyer like me is allowed to use that term about himself ) go awry! So much for getting a day in the shed - fat chance! Wall to wall family today. I eventually got another hour that's all. As I said to WF though, if you just stick one bit of wood to another bit of wood each day - eventually (in about 2149 at this rate) you'll have an aeroplane!

Anyway - are the rear fuslage doublers in place? Of course they are!

Were they in place before? Ha-hem! Er,....yes of course ()

Anyway, that done its on with he small modifications to F1. I need to mark of a circle centred on the thrust line, but unfortunately SLEC have cut a whopping big hole just there! No problem really, just plonk the plug back in and tape it in place,...

We now take a pair of compasses and mark a circle:

Mmm, another problem curtesy of the boys from SLEC! They have added the guide holes for the IC engine mount. Unfortunately, I'm not using that and the holes are going be just out of position but very close to where I will want to drill holes for the captive nuts and so possibly undermine that. Solution - plug the holes with some thin rods of hardwood and CA them in place, we can then drill the pilot holes for the blind nuts,....

Note that I have deliberately made the arrangement of the studding holes a rectangle rather than a square. This is because we are very cramped for space across the nose as it tapers forward of F1. Depth isn't good, but width is worse!

I drill 2.5mm pilot holes and then open them up to 5mm (clearance for the M4 captive nuts). Remember, when drilling plywood like this its very important to clamp a good solid bit of scrap wood behind, otherwise you run the risk of splitting the rear face when you break through. Drill slowly with light pressure.

That done we can fit the blind nuts,...

Tap them into place with a small hammer - just enough to hold them there. Next I'll use a screw, a couple of big washers and a nut to pull the nuts into the wood. Once in, a dab of epoxy will give us a bit of extra security.

And that's it for today - I must get a decent session soon - surely!

BEB

[Biggles' Elder Brother - Moderator]

Posted by Andy48 on 10/01/2016 20:46:55:

...but ...but ...but. I'd assumed you would use a BEC, however, Peter will have used a RX battery, probably under the fuel tank, and your calculations should have allowed for the possibility of that weight affecting the C of G on the original model as well as the motor and fuel tank.

Edited By Andy48 on 10/01/2016 20:47:36

Yes, but he provides no information, it could be almost anywhere! But as long as we have the wiggle room (which we do) no problem! As I have said - I'm not trying to calculate the battery position - I'm just establishing that I won't have to go through F1. Which I'm confident I won't.

BEB

[Geoff S]

I'm using the same motor as you and I'm going to use 4mm high tensile cap head bolts through aluminium spacers (50mm long x 10mm dia bar which I'm going to drill through 4.5mm dia.).

A couple of points - 1: how are you going to access the motor. I'm thinking of leaving the bottom open as I did with my Fantasy conversion last spring.

and 2: If I'm leaving the bottom open then I'll have a second hole through F1 like the that already in the SLEC CNC cut one to allow a flow of air to the esc under the flight battery tray.

btw I'm not totally surprised by the battery position. I had to push the 3600 mAH 4S packs right back over the wing on the Fantasy (also a long nose). It might even be worthwhile allowing the battery position to be adjustable right back to F4 if you haven't already.

Geoff

[john stones 1 - Moderator]

I was thinking ali spacers myself, (old heli booms), many's the ARTF that's come with pre drilled bulk heads I've had to plug, why they do it

John

[Biggles' Elder Brother - Moderator]

Good questions Geoff! And ones I'm still pondering TBH. I don't really like the idea of leaving the bottom open, but a hatch is quite a faff. Having said that even with access I might not be able to remove the motor - the best I could hope for would be to be able to repair a failed solder joint or the like. Needs more thought. I quite enjoy pondering over future bits like that while I'm building, or driving, or suppose to be working! The solution usually comes to mind - eventually!

Still only getting bits and pieces of time, so while there is progress, it is very slow at the moment.

I've drawn the captive nuts in with a bit brute force using a long allen key on one side and a small ring spanner on the other. Once in I gave them each a dab of epoxy. Probably overkill but it makes me feel better!

I need to modify F2 now. The top needs to go, because that will ultimately become the battery hatch, and I need to deepen the cut out to make sure the battery will sit low enough, on the velcro and with a strap, to get the hatch on! So here is F2 marked out ready for surgery:

And in the post-operative recovery room after its ordeal:

OK we are ready to start fixing the formers to one side of the fuselage. F1 first. All the formers have to go in square obvioulsy, but getting F1 square is absolutely critical. If there is one joint that the flying characteristics of the model will depend on most its this one - 'near enough' is not good enough here. The motor is going to hang off this and so the thrust line is totally dependent on it being in the right place and correctly aligned. It must be square both vertically - Peter gives us an excellent datum line along the top of the fuselage side for this - and horizontally. Time to get the square out of the draw!

The glue I using here is Deluxe Materials Aliphatic - my favourite! Its quite slow drying so you have plenty of time to fiddle about and get this right.

In about 30mins the joint will be strong enough to handle - gently! Aliphatic doesn't reach full strength in my experience for about 24 hours. But as I say after 30 mins we can remove the square and hadle with care. We can then add the triangle stock - which will very much increase the srength by increasing the glueing area. When adding the triangle stock I am leaving the bottom part just slightly proud The reason is that I can then sand them back flush with the slight curve of the underneath of the fuselage in this area helping me get more gluing area for the sheeting later.

We now simply proceed along the fuselage - adding formers making sure each one is square:

Its hard to see in that picture, but I have pluged the wing dowel hole in F2, which is too low and drilled a new one (5.5mm diameter) above it, 15mm up from the bottom of the former. To remember this I have annotated the drawing!

As soon as I have these formers in place I will start making a ply battery box. This will run from just aft of F1 all the way to F4 - lots of wiggle room. The box will be glued to the inner faces of F2 and this will go someway to restoring its strength after I have removed the top. So I have to do this before I join the fuslage sides.

BEB

[john stones 1 - Moderator]

Well how obvious is that...clamp the square to the former, and for years I've hunted the house for owt with a square edge then ended up with it glued to model.

John

[AVC]

This fuse looks very good BEB. Good advices and "tricks" also, like the one John's mentioned

[Geoff S]

Posted by Biggles' Elder Brother - Moderator on 12/01/2016 22:31:08:

Good questions Geoff! And ones I'm still pondering TBH. I don't really like the idea of leaving the bottom open, but a hatch is quite a faff. Having said that even with access I might not be able to remove the motor - the best I could hope for would be to be able to repair a failed solder joint or the like. Needs more thought. I quite enjoy pondering over future bits like that while I'm building, or driving, or suppose to be working! The solution usually comes to mind - eventually!

I like to do my pondering in bed in the morning whilst listening to the 'Today' programme on R4 and enjoying the luxury of retirement - though the drawback is getting older (that's relevant today as it's my birthday yet again! )

Leaving the bottom open isn't too bad. It isn't noticed on the ground once you've fitted the wings and not in the air, either. It has the advantage of keeping everything cool. I don't like building things in. Perhaps I'm a pessimist but I like access for maintenance.

It look more open than it actually is because the battery hatch is off and you can see right through.

Geoff

[Biggles' Elder Brother - Moderator]

Oh - Happy Birthday Geoff! And many of them!

Yes, you're right of course, access is better - and in that case where the battery hatch is above it will work great. But at the moment I'm planning that my battery hatch will stop at F1, so, even with the bottom open, I doubt I would be able to ever get the motor out without breaking the nose open. As I say, it needs more thought,...I may well see what it looks like with the bottom open?

Thanks AVC - not nearly as neat as your building though! As I've said on Chris's blog - I'm a bodger, but it usually all comes out OK at the end! Fingers crossed!

John, I usually use a clamp on square just to make sure the former really is hard up against it - as you know its very easy sometimes for the former to arrange itself so as to lean slightly away from the square!

BEB

Edited By Biggles' Elder Brother - Moderator on 12/01/2016 23:31:22

[McG 6969]

Hi BEB,

Regarding motor access, couldn't you consider your cowl removable from the front & sliding over your motor (as I projected for my GF one) down to F1 & screwed to it?

I didn't find any mountain top so far... but, in the case you should wonder, I'm now totally 'medicine stuff'-free.

Cheers

Chris

BRU - BE / CTR Access Control

[Biggles' Elder Brother - Moderator]

Well, its certainly a possibility to look at Chris. I'll keep mulling it over, we'll come up with something eventually!

Glad to hear you are drug free!

BEB

[Biggles' Elder Brother - Moderator]

OK, a little more progress today. I continued adding the formers back to about F7 or so,...

At this point I prefer to put it in the fuselage jig - the exact placement of the formers at the back end, where the fuselage tapers fastest, are easier to refine (read "bodge" then.

Of course the fuselage jig was propped up in its storage place waiting for me,....behind 5 large models . After a good deal of playing musical chairs with the models I eventually managed to extract the jig and then I just had to clear the bench to make room for it (note to self: try and be tidier and neater like Chris and AVC and not a mucky pup leaving tools strewn all over the bench!)

Anyway we got there and she's in the jig,...

Chris B's blog give a very good description of how to use a fuselage jig, so I'll not repeat that here. Suffice to say the central red line goes down the fuselage, lining up with the former centres and the tail closes over that line giving a nice straight fuselage (we hope!), as can be seen in the photo below,...

You can also see that I have added the triangular stock to all sides of the first bay now. The tail is not glued yet, it's just held in place ready.

I was going to build the battery box before joining the fuselage, but a pinch of F2 convinced me there was no need.

So, I'll leave all that to dry overnight and pick things up tomorrow.

BEB

[john stones 1 - Moderator]

You're moving along now BEB, your battery hatch is pretty much the way I am going

John

[WolstonFlyer]

Nice progress BEB, I am making notes! I am working away from home this week so no building time for me until the weekend

[AndyD]

i really must invest in a jig,been saying that for 30 years so this might be the year.

[Geoff S]

Blimey, your fuselage jig looks a lot cleaner than mine which is dotted with lumps of old epoxy and the lines have run a bit for some reason (some sort of solvent, I guess) but it still works a treat and is a valuable building aid. I struggle in my small purpose built workshop with tools collected over a 100 years or more by my father and grandfather as well as me. I can't think how those building on the kitchen table manage. I take my hat off to them.

Making progress. I'm letting all you clever clogs get on with fuselage whilst I build the wings more or less to the original drawing except for having 2 servos for ailerons. I'm waiting to see how you solve the motor installation problems. I always start with wings when enthusiasm is at its height because they have a tendency to be tedious. The fuselage is always the more interesting part for me so I save it for last.

Geoff

[Biggles' Elder Brother - Moderator]

LOL! Funny you should say that Geoff, I spend a good 30 mins going round it with a scalpel carefully scraping off old bits of glue and slivers of wood stuck to it!

BEB

[Peter Miller]

I don't use a fuselage jig. Once the front of the sides are joined square if the sides are the same length it should be square. A pair of mark 2 eyeballs to confirm it and that is it.

[Craig Thomas]

Re tidy work benches and small work areas. I do everything in a single garage. Everything in there is my stuff. My wife has the house and I have a garage. More than enough room you would think to build a toy plane , no way. I have stuff everywhere. The work bench looks like I've emptied a bucket of sawdust, tools and bits of wood all over it and another couple of buckets full on the floor. I have two benches, and have a battle to put anything on either of them. Your half way through doing something, put a tool down for 10 seconds and then spend another 30 seconds looking at all the clutter trying to find it again.

I will learn to put things away one day. 😫😫😫

[Bob Cotsford]

Peter, that's how I've built for years just marking centrelines on the formers and lining them up by eye, but last year I treated myself to a SLEC jig and it really does make life a lot easier.