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Member postings for Erfolg

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

Thread: Gluing laser cut kits
06/07/2020 16:34:32

I have a small number of models built from laser cut kits. To-date I have no joint failures as far as I am aware.

A reasonable practical test is to take one of the scrap pieces (which has been cut),from the supporting sheets, then glue it edge on, onto a bit of scrap. After the assembly or assemblies have dried, pull them apart. I would suggest a straight pull on one, on another, a shearing, torque type of load.

What matters did the joint fail, or the wood adjacent to the joint. If the joint fails, it matters, if it is the adjacent wood, it does not matter. Adhesives like PVA rely mostly on penetrating the wood for a small distance, when the wood fails it proves the glue has penetrated, and the wood has less strength than the glued joint.

A real test is always much better than hypothesizing.

Edited By Erfolg on 06/07/2020 16:34:53

06/07/2020 13:07:52

Ron, what are you really asking?

06/07/2020 12:40:29

No, I do not.

I guess some argue that there could or will be some residual dust or ash from the cutting process.

Although I have never considered the possibility, nor have I observed any dust, which may be present, I have never noticed it. The box the kits come in do not seem to have any dust in the bottom either.

If there is any dust, I would argue it is trivial, to an extent that the PVA just incorporates it into the joint, without any issue. Likewise with Cyno.

I guess all sorts of arguments ca be made from die cutting and routing, I believe I would remain unconvinced of any problem.

Thread: Carbon Fibre Tubes
05/07/2020 14:29:40

If seeking a solution that most closely matches the loading conditions of wings, something that looks like a "I" type beam, which could also be a box beam, matches the requirements. In general there is very little turning, or bending along the axis of the NA of the wing.

In the real world of modeling, tubes work extremely well, for a number of practical reasons. In bending they can be pretty near to the "I" type beam solution (when optimised). Tubes are more often than not of the shelf items. Their properties can often be known with some certainty, although probably not in the modeling world. Incorporation into a wing is often much faster to do than the conventional spar arrangement

IMO the success or failure when using tubes will be the detail, of how you use them. You rarely see a wing these days fail. In part due to current practices no longer mimicing FF practices, where weight and ease of transport and so often was the design criteria. Being honest, the +50cc aerobatic models look flimsy built to my "Battleship" engineering eyes. Yet I am obviously wrong, as they survive the extreme manoeuvres they are subjected to. UC on the other hand, seem to fall of at alarming rate, as part of the landing process.

Just do what you think is OK, and I am confident that all will be well.

Thread: Lightwight foam cowl, Tissue with EZE Dope or thinned PVA?
05/07/2020 14:08:05

Whem you come to finish your model a few pictures to help.

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I trust yours will not be gutless. Is it an own design?

I increasingly use WBV on foam with cloth.

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The wing tips on this are blue foam with WBV, in this case Ronseal Hardglaze, which is a bit harder than Wickes or Toolstation, at a much higher cost. Is it worth it? Only if you have some left over from an other job.

I have used tissue paper on Blue Foam, for me not good. The model below is a combination of WBV and glass and tissue paper and PVA.

This is what it should look like. In my model it has never been finished as a suitable power plant has not been found to provide an acceptable CG.

I increasingly take the view, that most systems do work, if care is taken. More skilled people than me will achieve good finish with light weight.

Thread: Carbon Fibre Tubes
04/07/2020 10:59:01

I know, or perhaps sense, that there are a few engineers or in my case ex-engineers on this site. The design and construction of beam arrangements, is pretty much second nature. Then there are contributors who are intuitive to the requirements.

Yet separating out good arrangements, from the poor, is not always as obvious and easy as we first think.

We have all seen in the past, the beam going through the centre of each rib, not the best way of making use of the available material, from a structural perspective. Yet from a kit makers perspective, the arrangement jigs the wing ribs to some extent.

It is pretty much the same with the various tubes. An "I" beam would be generally be better, than a tube. Yet tubes are readily available, and just as important can be incorporated into the wing very well. A continuous removable "I" beam is generally not available to us and the practical issue of getting the flanges to the outer surface would be difficult.

Much of the success of a design, relies on the detail as well as the materials etc.

The sliding tubes should pass through a number of wing ribs, the more the better (to a degree) to distribute the loads, via the ribs. In my HK Waco SRE, this was not the case, as built. It would be better that the tube was fastened (glued) to the ribs, as this would better transfer the loads, more evenly, as a principle. In practice this often defeats the objective of some tube arrangements.

If a tube fits within a tube, the arrangement of the HK Waco is to be avoided, where the inner tube, is short, in that it does not pass through a number of ribs (inside the tube). In this case a stress concentration took place at the end of the inner tube, the wing root rib acting as a fulcrum point.

CF and GF manufacturing lay ups come in many forms, You get spirally wound strands, longitudinal, braided weave and probably many more, that I am unaware of. They all have there characteristic properties, that differ significantly. That is before you get into the resin and processing and weight of the composite.

With metals, I was lectured, time and time again, processing history matters a lot. In other word what has been done to say steel, such as drawing, when cold, or hot rolling and so on.

At the end of the day, we have model aircraft, where theory, is one thing, carrying out theory is another, practice not always closely matching theory. That skill levels do vary, from my rough and ready, to artists with a scalpel and balsa. What decides me generally is what I have got and what I can readily get.

In general I have found that observing old bridges, often provides a clue as how to deploy material, Victorian Builders can be good for this. Yet you also see the situation where the view is taken, lets keep it simple, and forget the economical use of material, as the benefit if frugality is limited. Modern casalated beams, indicate the principle of the "Parallel Axis Theorem", where the "I" beam is the idea in its purity.

So with respect to our CF tubes, as long as it works, does it matter if the arrangement is not the ideal solution? As everything is pretty much a compromise.

03/07/2020 20:27:11

Bob, I think I know where you are coming from. The but is, I have seen a number of F3J and F3b type gliders with solid SF joiners which appear to be about 25 mm square solid joiner.

It does seem there is no one answer or correct way of doing things. However some of the concerns are worth noting. An example is the the observation that an arrangement can bind solidly.

I must admit that a wing loading of 35 oz per foot square initially has me worried. Then I build small models, if the model is big, it is possibly quite low.

03/07/2020 16:56:00

A lot of +50cc Extra type models (that I see) use a single Carbon spar as a push fit through what appears to be light ply wing ribs, with no trouble.

On the other hand my HK Waco SRE had a aluminium inner wing tube, inside a Carbon outer. Much to my surprise the carbon tube shattered, leaving a wobbly wing. There was a lot more wrong with the model, but that is bye the bye. My repair just used an outer aluminium tube.

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At the end of the day, there seems to be CF tube and then there is CF tube.

Many of my open gliders used either a GF or CF boom (fishing rod, deep sea type of size), which never broke without my arrivals. On that basis both materials can be great

On that note, I would just observe that like any other component or assembly, the material in itself is not always the answer, it is the detail of how it is used. Also I would be concerned about the potential binding/seizing issue raised.

Edited By Erfolg on 03/07/2020 16:56:58

Thread: Lightwight foam cowl, Tissue with EZE Dope or thinned PVA?
03/07/2020 15:34:54

KC

I expect that it is a case of "there is more than one way to skin a cat".

I can see the logic of soaking for some time, in that the fibres making up the drown paper will soften, or probably soften. How much of the PVA will soak into the paper, will depend on the paper primarily. I can see benefit in getting PVA into the paper, to toughen and harden the material.

Personally, now, I would not dismiss Newspaper as a material. That is mainly due to my work with my granddaughter (no. 3), where papier mache produced a surprisingly strong result, at low weight (although weight was not an issue). Recently I did use the method to produce a cowl I think. I did not use it opting for another solution. The bottom line is that it does work, if done properly. I am still racking what is left of my brain as to the intended application.

Edited By Erfolg on 03/07/2020 15:36:32

03/07/2020 11:53:36

Picking up on Simon's option, making the assumption that traditional modeling tissue is not to hand, then Man Strength Tissue paper hankies of the disposable type, are usable. Not quite as strong or necessarily as easy to work, they will work, may be requiring more layers and care on application.

I have tries the tissue paper of the type that comes as packing with shirts. I found that it is more akin to the Japanese suff, in that it is much harder, also does not accept dope (probably a no, no with foam) as well, although sticks with PVA.

I have tried the type of tissue that is often found in low cost card shops, some is like the stuff that comes with shirts, other similar to model aircraft types. It all depends, it seems. Very cheap though, typically about £1 for a few sheets.

In recent times I have good experience with Newspaper and wall paper glue (cellose). I have made a prehistoric cave and camp, a Viking helmet, and a "rain cycle).

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There is a lot that can be done with scrap materials. Living at the end of the road, I am increasingly learning how to live what can be found around the house and the local non specialist shops.

Thread: HobbyKing ,AHHHHHH!!!!!!!!!!!
02/07/2020 18:02:29

I agree that there web site is now pants. Searching is now a real chore.

The stock levels are not what they were, at any of their depots. Yet far better than your LMS if you have one.

Still good value for money, compared with who ever you choose.

I cannot but notice that many others have come and gone, in this sector of the model trade, or are not what they were, I do not want to mention names.

At present I get the impression that France can be a major hold up for goods coming from China, destined for the EU and UK if the ship docks say at Brest etc.

I am guessing in that many Chinese suppliers are also having their difficulties. On that basis, if true, so will HK.

Thread: Lightwight foam cowl, Tissue with EZE Dope or thinned PVA?
02/07/2020 17:51:51

The foam type may matter. Some things do not like all foams. Dope can be one, cyno another.

I tend to use surface glass cloth, as it drapes well in all directions. More often than not I use WBV (water based varnish), if I just want to resist minor dings. If I am looking for strength, I would use Epoxy Resin, although heavier and a heavier lay up.

I have used brown paper parcel tape, works well on simple curves, and can be very tough. Vic Smeed even made model boat hulls out of it. Not particularly light weight, if weight is an issue.

A lot depends on what you have to hand. An example is parcel tape (paper) once freely available and as cheap as chips. Now a lot depends from where you buy it (if necessary).

Thread: Aeronca Sedan
02/07/2020 14:59:33

As is usual, not everything goes to plan. Indeed much of what could have been planned ,has not.

I had written that I intended to start on the wing. As I laid out my plan I realised that I needed to have the central part of the wing as a starting point. On the full size this part is part of the cabin/fuz. Indeed the Mercury approach was follow pretty much full size practice, with, plug in, wings that sprung out on an arrival.

I have dithered on this area, for some time. I had decided that I needed a hatch in the cabin roof to gain access. This would allow for the mounting of servos, Rx etc. The mercury approach was a door on the right hand side (from memory), for this purpose. I was and am not enthusiastic to this approach, as a significant re-enforcement would be required to replace the lost integrity caused by the opening.

I was not keen on a hatch, as this required plug in dowels, such as used on model gliders.

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You may recall that I still have a selection of joiners. From high strength aluminium, brass box and steel strip, a selection of brass tubing and piano wire inserts, and some polyester spar capping (made from glass string).

I have a few brass box type arrangements that were salvaged from a 144" fling wing that I built, with the gliding characteristics of a "lead Butterfly". Which unsurprisingly was consigned to my bin of failed projects.

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I weighed the bits that immediatly came to hand, which came out at 50gram each. Without to much imagination, I realised that I was looking at +100g assembly. I have never been to impressed with the brass tube and piano wire arrangement, other than a glider on tow, could benefit from the piano wire bending at the root body interface, if over stressed, rather than some part of the wing failing. There were other permeations, which benefited from the parallel axis theorem, if bolted up solidly. All were pretty heavy, in practice, although there would not be any failure at the root.

I spent a lot of time planning to make a solid epoxy, glass tow/string joiner often seen on modern high spec gliders, something approx 12-15mm square cross section at about 300 long. Then the doubts set in.

On balance I thought, you know, this is a light, civil aircraft, at best stressed for simple aerobatics, It does not need the strength of a tow line glider or a aerobatic model, that will do a Lomcovac type manoeuvre.

On that basis I have decided to run the spars into the cabin to area, and just rely on ply bracing and shear webs on the rest of the wing. I will put enough (I hope) material in the cabin to area to resist any crushing tendencies. This will now be a one piece wing. At 58" span in this era not big.

So what has taken me so long to do apparently nothing? Well, I am slow, plus most of the area is ply, needing a lot of sanding. Ah, yes, that indecision.

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Just about ready to start what I intended doing about a week back.

I am still on track, relying mostly on my bits boxes.

Edited By Erfolg on 02/07/2020 15:03:18

Thread: How far do you travel to the nearest decent model shop?
29/06/2020 12:05:12

I am surprised how many have a model shop within 30 miles @ approx 57%.

In my case I am in the 3% group, where the nearest model aircraft type of model shop is @ 70 miles each way. There are odds and ends type model shops, which may have the odd thing that can be used on model aircraft, that are nearer, but not much.

On my personal situation, I am surprised that only 18% buy on line.

All of which goes to show, that your personal experiences are often very different to others.

Age is also possibly relevant, as in the past, I travel a lot more. Specifically to Scotland once a month to Edinburgh, Inverness later to Aberdeen. A few more miles to another town seemed part of the break. Now living at the end of a road to nowhere else, traveling 60 miles to Manchester seems a long way, then, where to park the car?

I have not been to Webbies for over +4 years now, my now local, proper model shop. A shame as their level of service and bonhomie is exemplarily.

Edited By Erfolg on 29/06/2020 12:06:54

Thread: Aeronca Sedan
28/06/2020 14:00:08

I am finding a major problem with this particular model, which I am building from the proverbial off cuts box, is keeping the bench anything approaching tidy.

Habitually I put all the tools back to predetermined homes, the majority on my IKEA Billy book cases. Except it seems when I make some slight progress, where I find piles of tools of varies types. Saws, French Curves, set squares, sanding blocks and piles of bits of wood I have been going through, from the offcuts box.

My other issue, is that in some instances I have deviated from my drawing, and more work is then required to get back to how it should be. Then again, the various links that have been provided have shown that some of my structure is pretty beefy compared to full size. Although I am very much a it must fly well, but should bare some resemblance to scale when viewed at twenty feet whilst squinting, type of modeller, I am beset with internal, self inflicted issues as to what extent to compromise. The other issue is that my detail design follows the practices of PM and a certain Gordon Whithead "Scale Aircraft, for everyday flying", where I seek reassurance that what I have drawn is practical, robust, sympathic to the full size. At the back of my mind, is a issue, where I was less than happy with some one elses design, I let it go, latter came to regret it. Design can be both fun and a battle with your own internal demons, Hmmm, time for a whisky, whilst i contemplate what PM and Gordon would do.

Yes kits are much easier, ARTF, require no thought and almost no skill. Perhaps that is the way of the future.

Thread: Blue Foam
26/06/2020 16:11:19

Martin, pleased keep me informed.

I am happy with a 8 * 4 sheet, could keep going for another 10 years, if i last that longfrown

Thread: The Lockdown Restrictions Have Been Relaxed. Who's Been Flying?
26/06/2020 15:38:27

It now seems that the Lockdown is well and truly over. Everything has returned to normality, the three practical routes to our flying field all have road works on each, complete with traffic lights. Holes dug, barriers erected, all coned as per regulation. The one thing missing, is anybody doing any work, or any one to be seen (one has been like that for months now).

There is one small change, and that is the massive ques of traffic heading either to, or from the beach areas. Fortunately I travel against the flows, although in awe of their lengths, a mile or two. I am not surprised at the Bournemouth news item, when I got home last night. I guess it is not safe to go back to work though? I guess it is just like being retiredfrown. Although we do not now walk to the beach for a walk, due to the crowds, even on the pavement areas.

On that score I have manged a few visits to the field, with mixed results. I lost a fin on my delta, which flat spun to a landing. I managed to spin my Nobler in, trying to avoid a mid air, apparently we no where near each other. I had a tense 15 minutes with my Profile Basic model, as a new 2200 Lipo, replacing a 1800, ended with me putting the CG to far backblush..

Was there a plus side, well yes, my +30 year old trainer flew with no histrionics. Then over the three days i have gone to the field this week, other members have turned up, producing a core of flyers.

Ther were a few hiccups that other members suffered, all taken stoically, in no way diminishing their pleasure..

I have replaced the fin on my errant delta, which has now flown again successfully by test pilot (who appears to be an occasional contributor to our mag and one of the now diseased mags, from what I have seen in this months mag). The Nobler is ready for another flight, I have nudged the Lipo forward on my Profile model.

If it was not for the wind here, at about 14mph (always windy here, so it seems), all would be well with modern world. Oh, that is other than the hordes, swilling beer, eating take aways on the green (adjacent to the beach). You should see them run when a sudden down pour occurs, like lemmings into the main road. I know what you are thinking, thank God, that Erfolg is not one of those moaners.smiley

Edited By Erfolg on 26/06/2020 15:40:12

Thread: Blue Foam
26/06/2020 14:37:06

I thought it was on this thread that some one posted that Blue foam was an extruded polystyrene, whee a gas had been used to reduce the density.

Unfortunately Kingspan (which I had loads of the stuff over from two building projects) does have a low density/weight, yet is unfortunate friable and low strength compared to Floormate.

In many ways Depron seems almost the same, but comes in pretty thin thickness, like 6mm. My Blue Foam was, or is 50mm.

There was also references in the past to Pink Foam, is that still available? Again is it affordable. My 8 foot * 4 foot sheet cost a £10. In my case I had to saw it in half to get in my car.

25/06/2020 12:02:09

Danny Fenton has written that Blue Foam from Dow, marketed as Floormate is no longer available.

Does any one know of a replacement, as I do use it quite a bit and am running to the end of my stock.

I used Floormate X200 in the past.

Thread: Aeronca Sedan
25/06/2020 11:57:34

I did say i was going to work on the wings. Hmmm, as frequently happens i have not.

I have been struggling with the cowl area. Lots of hangar rash, and it still needs lots of extra work.

I invaribly end up with tail heavy models, even with the Lipo In-front of the prop, I need lead, in genera, that is. On that basis I want to be able to remove the cowl, to insert lead under the battery box, This has lead to loads of problems. Much to my surprise, the model already seems unnecessarily nose heavy. On that basis much of my efforts will be wasted. On that basis until I am confident, that I will not need lead, I will not glass the nose with glass cloth and epoxy, as I may need, or benefit from permeantly attaching the side and underside pieces, Just having a removable nose as on my 1/4 Cassutt,

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As you can see I have managed to get two thing wrong with the nose. The first is the top radius of the battery box, the second is the over-sized box for the Lipo, which has made things awkward.

I have now started on the wing area over the cabin. In the past I disliked cutting proper ply, being slow and hard work, needing a lot of sanding(when I did it). The old Dremel Jigsaw (which i have had for some time and the Aldi disc sander (recommended on this site) have made fast work of the first part, and improves accuracy and finish no end.

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