1/10th scale Blackburn Beverley.

[Phil Clark]

I have been glassing since the late 80's.........on many an occasions I have glassed indoors (converted bedroom workshop) where it's been bone dry & 18-20 deg C minimum.......I've still had problems with some resins......West included.

You pays your money, you takes your chances.......only trying to help

Phil

[Ken Bones]

As John Greenfield says, have a look a G4.
I'm a big fan of it since John introduced me to the stuff 15 or so yrs ago.
I can think of at least 10 of my models that have had the G4 treatment all with very very good results. So much so that I don't think I would bother trying another finish system.
Bonzey

[MalcolmDouglasPorter]

It would seem that some of you guys may have grasped the wrong end of the stick, but if you think I am doing something wrong with this project, do tell me, I need to know, but do not be upset if I decide to do it my way, or an idea given by someone else. I intend to get it right one way or another, but preferably with your help too!

[DAVE JOHNSON]

Hi Malcolm---I am also a fan of G4 pond sealer for glassing----I have covered many airframes in my modelling career,using different epoxies---even tried Varnish as some have recommended on here at times,but the G4 is the best in my mind--it goes off nicely in any conditions--its easy to sand as well --at the end of the day ,its your call which you use----
on another point,i have spoken to the Blackburn Heritage for you---they only operate on a Thursday so should be in touch with you after tomoz-----keep up the good work---DAVE

[stuart knowles 1611]

Don't apologise for anything Malcolm, you have a great build thread that we all enjoy and benefit from. That said, I feel that people are only chipping in with their personal experiences and trying to be helpful - take what you need from it - it all adds to the overall picture

Build on!

stu knowles

[MalcolmDouglasPorter]

I refer to my comments relating to the waxy substance on resin. Amine Blush, is caused by excessive moisture during the curing process. I learn from your comments that this can happen even in dry and warm atmospheres, therefore it can be a real problem. However, several of you have recommended G4 Pond sealer as being a good product for our use, so I did a bit more research and I discover that G4 is made to cure in damp atmospheres, it needs moisture to cure. It would appear that this is the ideal product for model aircraft as I am sure that many of us work in less than ideal conditions. I read that this stuff can be used in damp conditions AND low temperatures, sounds perfect to me? I would say that my small amount of research has been very worthwhile. G4 it is!

Finished most of the ribs today. Just the two end ones to cut from 8mm ply. I may need to re-cut the two current end ribs in birch ply to provide some extra stiffness for the fin attachment. I am considering fixing the fins permanently rather than removable. This tail assembly will be big but probably stronger for being fixed. Tomorrow I will make the leading edge stiffeners and perhaps the rear stiffeners, I have house chores to do as well. Once I am happy that the tail plane is fitted about right, I will need to work out the cable route and servo positions etc. Some tips on mounting the servos will be useful?

[MalcolmDouglasPorter]

You'll be pleased to know that I have ordered some G4 today.

I did the jobs I expected to do today, made the Leading Edge Stiffeners and the rear spars. Lots of small adjustments to do including straightening the LE stiffeners that are suffering with bananaitis. There is another spar that fits quite close behind the rear spar but at an angle. I am thinking of casting some resin between the two once the hinge mounts are in place. This should provide all the strength needed to support the elevator operation. I recon the elevator servos should be positioned about halfway along their length and the linkages near to the central hinge position. Any thoughts on this?

[Phil Clark]

How are you proposing building a twist free surface in 'mid air' like that.........normal practise is to use 'jig tabs' on the undersides of the ribs so the saurface can be built flat on the bench.

Casting resin = HEAVY......definitely to be avoided at the rear end. Some hard balsa blocks should be all thats needed for hinge supports.

[MalcolmDouglasPorter]

I understand and fully accept what you are saying Phil. What you are looking at is a dry run during the progression of making parts for the tail plane. I am not ready to glue them as there is a lot of work still to do. This is not a laser cut, pre-chewed kit. I designed this model from nothing more than an outline gleaned from several sources over several months. I produced my own drawings which are incomplete due to the “unknowns”. I am having to make decisions on the hoof either because the solution to the problem becomes obvious or because friends from the LMA have given me good advice. There are many more parts to make, holes to cut, and fettling and adjustments to make, when it is all ready, I will assemble the tail plane in the best way possible. Perhaps my ideas and methods are a bit unusual, perhaps they do not “fit in” to the established norms and practices, but I will get it right. I recon that I will not assemble this on the bench as that is not quite flat enough, it is likely to be assembled on the workshop floor which is flat. I know it’s flat because I built it!

I can tell you that this tail plane has been a nightmare so far. Despite referring to the drawing, despite taking great care over measuring and marking, errors are occurring. Just when I think I have sorted the problem on one part, and understand what I did wrongly, I mark out the next part, double check the measurements and cut it out. When offering it up to the assembly, this next “double checked part” also has an error. It is very frustrating. I am having to design repairs as I go, if “repairs” is the right word? Modifications is probably more correct!

What I have discovered so far is that these “repairs” actually make the model stronger even if it will weigh a bit more when complete. There are several conservative estimates on here as to the finished weight of this model, the consensus suggests about 120 lbs, if it weighs 125 or 130 lbs, I will not be too concerned. It may affect the size of the motors, but that’s about all I will need to worry about!

As you point out, I will need to “invent” some form of jigging when I do assemble this tail plane, it does need to be as square as possible.

[MalcolmDouglasPorter]

I had to "break in" to my own lounge Saturday morning as the latch went pear shaped and the door would not open. If I could have got to the other side of the door, I could have manipulated the latch with a thin thing, but I had to use bully tactics and split the door badly. Because of this, I didn't do anything on the Bev this week end, apart from using some scrap bits of lite ply and an elastic band in an attempt to straighten out the banana-isation of one of the ribs. Perhaps I might have to glue in some small noggins later on, prior to skinning? The picture shows the door occupying the workbench with the tail plane assembly on it.

Just out of interest, I will put some pictures of the door repair on my "Workshop Stuff" page.

[MalcolmDouglasPorter]

Not a massive amount done today. By the time I finished messing with the lounge door and all that. Feeling a bit head achy too.

Did a bit of fettling and adjusting things to fit better, made a stiffener cum joint for the centre of the rear spar, and have the tailplane tips marked out ready to cut in the morning. As I said earlier, this part of the model has been a nightmare so far. There are several joints that will need slivers gluing into them on final assembly. This does have a hidden benefit though, it gives you a little bit of flexibility to build the assembly nice and square. If a joint is cut very tight there is no room for any adjustment at all. This is frustrating though because many of the slivers are really small. It might be better to cut a bigger gap and glue in a bigger gap filler. I noticed too that the two ribs that will be fixed to the mounting box are not quite as square as I want them to be. More messing about to do there.

Oh, by the way. I had to disassemble the whole thing to do the adjustments. When I reassembled it I got the leading edge stiffeners on the wrong sides. This error has actually eliminated a problem. I mentioned that I need to straighten out the stiffeners that are banana shaped for no explicable reason, well swapping them over has cured it, not a lot to do to ensure absolute straightness. I could make the stiffeners from birch ply I suppose?

I did a small exercise to see how square the tailplane is to the fuselage. Using spirit levels, I squared up the fuselage on its stand, set the tail plane as square as my eyes allow, and measured to the floor, one side was 3/8th" higher. This was a bit of a mystery, so I checked out a few other things and noticed that the boom had become a little twisted sitting in the workshop. I used a spirit level to adjust this and the tailplane is almost level now. It seems I will need to jig up the boom when I skin it! This little lot is likely to change when the assembly is glued up? The final assembly will not happen until all the components are to hand, including some servos, and hinge making bits and pieces. It would be prudent to have this assembled and squared to the fuselage before I start on the fins etc. Squaring the fins, I predict, will be another nightmare?

[Alan Cantwell 1131]

Found a link to some plastic model pictures you may find usefull, In doc mitches huge hunter build, i lent him a large plastic model of the hunter, he found it extremely helpfull with his build, bit of a 3 dimensional reference file

http://www.sangereng.fsnet.co.uk/blackb ... rley_1.htm

[MalcolmDouglasPorter]

Thanks Alan, I have one of those, first thing I bought.

[John Rickett]

Malcolm,

With looking at the pictures of the tailplane, it appears as if its being built using ply. If so, it is going to add unnecessary weight.

I don't know the actual size, but guess the tailplane is 5 - 6ft span. Imagine it as a wing suitable for an aerobatic model, most builders would not construct one of those out of ply, especially if its going to be sheeted and then fibreglassed.

The ribs do little else than maintain the aerofoil shape so could be cut from 1/8" balsa. Balsa will also provide a better edge for gluing the sheeting than ply, leading to a stronger structure.

If you want to use ply for the spar then a single, full depth 1/8" spar will be adequate, any other sub spars (at the tailplane/elevator junction for example) could be made from balsa and blocked out at the hinge locations.

I accept that the tailplane has to support the fins, but these should not weigh much (if built using balsa) and the sheeted tail will be more than capable of supporting the weight. The flight forces on the tail of your Beverley are going to be low, much lower than on an aerobatic model. I would expect the greater forces will be from the propwash but would still think that a tail constructed from balsa with 1/8* balsa sheeting will be more than adequate.

Strength at the tailpane/fin junction can be simply achieved by an extra layer or two of fibreglass that is applied in the junction and extends outwards and upwards an inch or so.

I'd suggest you think about reducing the weight at the tail otherwise there will be a considerable amount of lead required in the nose.

[Rob Buckley]

I assume the tail will be removable? If not, the flight loads will pale into insignificance against the doorframe-induced loads just moving the model around!

[MalcolmDouglasPorter]

Indeed Rob, the tail plane assembly is removable.

John, I am not sure how much difference in weight between balsa and lite ply? Not great deal I imagine? The tail plane assembly, as it is, weighs in at just over 1 lb 2 oz. It is four feet span. The main spar is of birch ply and a strip of spruce, everything else is lite ply apart from the wing tips that are 8mm birch ply for connecting the fins. I plan on using a couple of small dowels each side to support the fins. The fins and rudder assemblies will be about two feet by one foot. Your suggestion of an extra strip of glass is a good idea too. The skin will be the same whatever I use for the internals. This weight will be reduced a little when I cut the various holes in the ribs, but then added to with the servos and their associated mounts etc. If the finished weight is going to be just a few ounces difference, then perhaps I could take the chance? Whatever I do, I will need lead in the front end.

However, I am not really very happy with my work on this assembly, too many mathematical errors on what has turned out to be a very complicated design. Perhaps I should re-visit this? If you intend to come and have a look in the near future, I will hang on till we can discuss some better ideas for this assembly?

Meanwhile, perhaps I should do some of the many outstanding jobs on the fuselage?

[MalcolmDouglasPorter]

Did not do any work on the tail plane as there may be some issues with this?

The studs arrived today for the undercarriage bottom joint. These will be cut to length and glued into place using some Cyno.

[MalcolmDouglasPorter]

Still feeling a bit grotty today, so didn't get a lot done. Just messed about with the studs, cut them down and glued in place. The Cyano does a good job of this. There are nuts inside the fairing to take the strain off of the inner frames. I feel there is little I can do in such a limited space. Perhaps I may look at placing some carbon fibre ribbon in strategic places, under the balsa skin. This will require grooving the frames sufficiently to contain the ribbon. Possibly some extra glass cloth on the surface as well? Having said this, the set up is amazingly strong as it is. The ends of these studs may well need trimming later on, but there are other bits to be fixed to them for the undercarriage, so I must leave enough for that application. I have also decided that the suspension legs should be remade, now that the correct position for them has been established, they do not really line up as well as I would like. These Oleo frames are about 1/3rd of their final thickness and will be much wider too. There is enough meat to be very strong, especially if I slip in a bit of carbon fibre.

It's nearly beer o'clock.

[MalcolmDouglasPorter]

Another one of those busy days that produced little to see. I have been messing about with the connectors of the two main fuselage assemblies. I made a couple of load spreaders to load across several ribs. These will not be enough as things are, perhaps I will fit some strengthening webs behind the locating bars. There will be a little flexing between the two assemblies at the moment, but this will also be relieved when the skin is glued in place and glass applied, but I should not rely on this, I may need to apply some glass or carbon in some areas inside to ensure sufficient rigidity and strength where needed. I also glued in the top connector bars that are working very well.

One of the major jobs on the fuselage is fettling the shapes of the ribs to a uniform profile. The shapes of the ribs at the front compound curves are assumed from the drawings, but some of them are clearly not quite correct. It's only by looking across the rib edges that the correct shape can be determined. I may need to complete one side first and if there is a big difference, I will trace a pattern from each rib and transfer the shape to the other side. Tedium springs to mind!

[MalcolmDouglasPorter]

Having watched the (disappointing) eclipse, I had a great day in the workshop. Decided to start some fun stuff, skinning the cam shell doors. This is probably the most complex skinning part on the whole model, lots of curves and twists!

I use a marking gauge to cut eight 3/8" and two 1/2" strips from the 4" sheets. It seems to me that the narrow strips are better to negotiate the compound curves, and 3/8" is about right for this application. I will probably get away with wider cuts as I progress, but I can only judge this as I go.

I also fitted the load spreaders I made yesterday, and this seems to be adequate in the front half. There is a little flexing in the cam shell door area and this is what led me to start the skinning. I will assess if I need any other bracing later on.