Erfolg

I almost remember rationing, do remember playing with an old buff coloured ration book (simple times). The Germans had been of rationing for years, no Socialist, market controls for them. I remember a class mate bringing in an old British and German handgranade to school. The pride of the teacher showing the class the superior British model, against the inferior Kraut stuff. I do not remember how he knew it wasn’t live. My dad kept a tin full of bullets under the stairs, had his obligatory trophy handgun (handed in years later). Yet gun crime very low, in that era. We as kids used to plunge down the side of the local slag heaps on our bikes. Yet the only deaths I remember were two friends separately killed by buses. Not by falling of the open platform at the rear. That was in the days before Health & Safety Happy Memories, well almost Erfolg

I personally ensure that all my purchases are below £18 (EU inspired waiver below this threshold), so I may make multiple individual purchases, to stay within the rule. Gifts, are deemed to have no value, but if of obvious value HM Customs can become interested. If the gift is not truly a gift, you are technically breaching UK regulations on imports. USA traders tend to be to the letter of the law operators. HK/Chinese/Taiwan/Singapore traders are often opportunist and provide a good service, however they operate. Regards Erfolg

Both Mikes It is obvious that you both know and understand the opportunities and limitations of Soldering/brazing systems. You use your knowledge to your advantage. You do read from time to time of modellers, particularly scale models in competition, where the undercarriage has failed by bending near a joint, attachment point. In these cases I suspect a number of them have inadvertently weaken the parent material. As is known the soldering/brazing is a wetting process, where the oxide film ahs been removed from the surfaces to be joined. The flux prevents the reformation of oxides during joining. Thereafter the object is to use the solder to wet the surface (bring into intimate contact), so that there is no gap or film between solder and substrate. Where the sections are heavy i.e., two bars and binding, particularly where the oxides have not been removed totally and suface protected, there is a tendency to pump in the heat. Many young modellers do not have a scientific or engineering background. They know lots of other things of which I am ignorant. Helping this group to know more about the materials and structures they use in this wonderful (or men playing with toys as the wife calls it) hobby, will I am sure enrich there lives and move some to successful building, rather than just ARTF models. Regards Erfolg

Phil I have a lot of sympathy with your position. We expect that most equipment to have been evaluated, tested and checked by the manufactures, when we purchase industrial or even domestic products. The model trade, particularly with electric flight equipment, does not have or provide information of the type you mention. The need for balancing is implied, by suggesting dire consequences from omission. The trade abounds with experts, who give well intended cautionary advice (which any Health and Safty advicer will automatically give). Modellers who push the boundary of the advice are advised that there are risks from their activities. Warnings which are not based on substance, that is a measure is bordering on Witchcraft. It is just as helpful as telling some one if you go running, you might fall and twist an ankle. Yes it does happen, but this event type can happen to walkers to. Misses out information which might be relevant, is the ground flat, is it a track, the age of the person, is it daytime or night etc. I do balance my cells, but do wonder if the practice is as effective as the Elephant pills and anti Penguin wires I have recently installed in the garden and roof of my house. You are right in my opinion, we need more facts, less generalised statements from the experts. Regards Erfolg

Steve This is the sort of discussion required. I would suggest that that +220C is the melting point of the Lead free soft solder and soft soldering is taken to be a process up to 450C. There after called Silver Soldering etc. My point is, it is easy to exceed the temperatures where the structure of the material is changed. You suggest 300C, that is a margin of about 80C The values you quote are not that dissimilar to those I recognise. What is important is that it is easy, using a blow torch, to get into the temperature range where you are changing the structure, in a way which you prefer not to. I am trying to reach a group of modellers who are not aware of metallurgy, but modellers such as yourself could help by broadening there knowledge base. I use these forums to gain an understanding of science where my knowledge is less than I would like. During my electrical and instrument and control lectures I used to think, what do I need to know to pass the next exam. I know regret, dismissing whole tracts of information as "that wont come up in the exam”. I now think, what happens if you increase the diameter/length/windings/number of magnets/number of teeth/number of poles/ in a brushless or other motor, I do not know the answer. If I had been more inquisitive I might. I do despair, when I hear modellers (I am also probably guilty) hold forth, with total conviction, with half truths and down right superstitions, dressed up as fact. Two way discussion can help understanding, help us establish the important issues and above all educate. I know that I am not always right, when I am, it is often under a specific set of criteria. In this post industrial Britain, there are far fewer people with both practical and scientific knowledge, I suspect that most aero modellers are both practical and theoretical people, who deep down want to understand. When I stop asking why, what if, I hope I have died, not mearly brain dead. Erfolg

I know that Myron was giving me a little tweak. I was really considering attachments that are subject to forces or stress, (if you prefer). Will soldering effect the grain structure? Absolutely. How much, depends on how much energy you put in. On undercarriages, could well be the cause of all those un-expected bends after landing. What I would like people to do is consider what has happened, (in all events) and think why. I am sure that all the metallurgists out there, are often in despair at the lack of interest in a fascinating subject. Ask yourself this question what is a soldered joint? Are the two materials made as one? What is the nature of the joint? What is the difference between a soldered, Silver soldered and brazed joint? I am not a Metallurgist but, if you really do not care or wonder what is happening at a theoretical and practical level I really think you are missing out, and will not be able to get the most out of your creativity. Metallurgy really is fun and is practically important to us modellers. After that impassioned plea, I will go back to the bottle. Non Metalurgist Erfolg

The difference appears to be, that we are a high tax economy. Where as, the USA is generally a low tax economy, that is from the perspective of local sales tax and the equivalent of the rates that the shops must pay. When you consider that the UK import taxe tend to be compounded, it becomes scary. In the past I was advised that HM Customs do not like personal imports, because they are both time intensive and tax can be evaded. Therefore the idea of having import duty on the goods, plus vat on the value of the goods + the duty + postage + handling charges is both logical and profitable to the Government. It discourages the average person. At the stroke of a pen on a few pieces of paper, increases the value of the goods, now that is a high efficiency economy.

Cermark Breeze certainly fix the bill RCM Swift from the Czech republich Any of the old 2M, 100inch, Open competion Gliders motorised would also do. Generally they are over engineered in the wing design (to take the tow line,winch forces) suitably lightened do work. Generally looking for a good alround wing section E205, MH 32 or whatever takes your fancy in that type. Steve Mettam sells models and gives good advice on Electrics. I think he competes in Electro-slot, gives an insite to all condition flying. Seems to trade under two names (Modelhaus, Electric Model Co.), he is often in the RCM&E adverts.

Many years ago, a mere youngster, I asked my dad for help. Dad I need to solder these braces to the main under carriage of this model. I cried. Dad said is that really a good idea? The main part will never be the same he opinioned. In that era possibly 60% of the male working population had some useful knowledge of metal working, their was a strong manufacturing base to the UK economy. Years later when studying for my degree (no one else’s), I was let into the dark practical arts of the tradesman (who knew the answers, but not the why) at a theoretical level. The first was that processing history was responsible for a significant part of the properties of a material/component. An example, why a bright flat bar will bend if machined on one surface only, processing history of course. This brings me back to soldering undercarriage legs. The properties of the piano wire we use is very dependant on this processing history, introducing highly directional characteristics, that are useful to us modellers. The point is, by heating up the wire we modify these properties. How you all cry (none engineers anyway), by modifying the structure of the parent material. That answers nothing you all cry again. I answer. During processing the material is work hardened very directionally, producing a fine elongated grain structure. I now exclaim that by heating to solder, braze, or even weld, this structure becomes modified. The more heat put in, the greater the modification. Enough heat and the carbon steel becomes annealed. That is the softest, ductile etc condition at room temperature. What has happened, is that the grains have been provided with enough energy to adopt the most low energetically favoured shape (tending to spherical) that any individual grain can achieve, some of the grains will have formed a larger size. As the grains get larger the areas of disruption in the grain boundaries become greater. It is these areas which introduce weakness. Also our directional properties are disappearing. It is for these reasons that the heat effected zone will often be the site of unanticipated bending etc. It is often to avoid bending that the soldering was done in the first place. So it is often better to have a mechanical joint (in my opinion) of some type than to go pumping heat into a metal. It is now time for you Metallurgists (or Engineers) to contribute, please. Regards Erfolg

As I was saying reducing conditions are a favoutite, in addition are chloride attack (washing up liquids , any of the Halogines), intergranular corrosion, galvanic corrosion. I had occaison to be involved in sentancing, a significant quantity of Stainless Pipe that had been left for years by the coast. When the material was drawn for fabrication, it was all scrap, pitting corrosion, chlorides in the sea air. I also noticed that my mothers stainless steel cutlery was showing pitting corrosion where the handles were welded to the fork, dished portion. Clearly showed the effect of disruption in the grain structure from the welding process and washing up liquid causing the pitting. Its good to know there are others out there, who have an intrest in Millers indices, Weibull modulus etc. Regards Erfolg

As I was wandering to the newsagents for my daily paper, a sudden shudder ran down my back, I had just made another mistake, re stainless steel. The principal alloying element is chrome at up to 26%, I think the max for nickel is about 10%. The point I was trying to make all these materials were in short supply, for the Germans during the war. Point of intrest it is a chrome oxide film which makes stainless, rust free. Therefore remove the oxygen, damage the film and let corrosion begin. Shamefaced Erfolg

Alistair I would be suprised if they used stailess steel for two reasons a) Stainless steel contains nickel in the region of 18%, does vary dependant on type (Austinitic, Martinsitic, Feritic). As nickel is very useful in making high temperture alloys, Nimonic etc. and being in short supply, I would think it would go into Jet Engines. b) The properties of stainless steel are not that different to some Carbon Steels to make benefits debatable (UTS, Youngs Modulos etc.) Does work harden nicely though. Should not rust in a Oxygen environment. It is of passing note that many of the aluminuim and magnesium alloys used extensively in Britian (after the 2 nd War) came out off the Germans need to find high strength low weight materials. Regards Erfolg

Returning to your original thread on winding springs. Some of the statements made were right (at least in the distant past). The large conglomerate where I trained as an Engineer (the practical bit), wound some of its own springs. These ranged from small instrument springs to large springs for control valves on steam turbines. What is interesting (well maybe) is that small springs were wound on mandrels etc. and that was the end of their manufacturing treatment. In the case of large springs they would be wound, ground (ends) and heat treated. I was told that in the case of small springs the most satisfactory way was a) Buy die drawn wire, where the processing history and base materials produced a wire, with very directional properties due to the work hardening from drawing, drawing also have produced lamella in the grain (and elongated grains) structure due to the drawing, further increasing the directional properties. The subsequent winding process further stressed the spring, which preffentially returned to its formed position because that required the least energy. This method could only be used where the springs were small, to large and the outer or inner surfaces would exceed the UTS and fail (crack). The other limitation is that the stressed position has to be less than the UTS. Small springs of this type will often fail due fatigue as the stress level is above the indefinite cycling stress level. Any heat treatment would, (such as annealing) would destroy the benefits from the processing. The longer you anneal the larger the grain growth, large grains produce a weaker material. b) Large springs were wound from the “normalised condition” as the winding would introduce directional stresses that were high and the forces required to wind wer also high. After winding any grinding would be done prior to heat treatment, as the grinding could adversely effect the structure locally (heating). When wound, the springs would be heated to above the upper critical limit (the red heat ) just sufficient to get the outer layer to temperature and the core to a lower temperature. The springs would then be rapidly cooled to prevent a phase change (it’s the compact atomic structure at temp that produces a harder material). The cooling velocity being dependant on the composition of the steel, some requiring water if a very hard outer shell is required, often oil (lower cooling rate). After this they would often be heat treated to reduce the stress level. I have had to leave an awful lot out because there are many issues regarding the effects of alloying, processing. I personally think you should try to bend your springs cold, forget about heat treatment. With Aluminium alloys I could write many pages. The bottom line these days most commercial alloys tend to be the Silica types (cheap), the precipitation hardening etc. being for high strength applications Aircraft, Bicycles (7000 series) etc. Regards Erfolg

It is not apparent to me what the (fundamental) differences are between the D9 and 152 other than wing span. It is apparent that the D9 took a standard 190 airframe minus the engine and attachments, and inserted a section in the aft end of the fuselage. A Junkers engine was then attached (211). The first Versuch (research) 152 airframes took D9 fuselage and engine and attached a new wing. In the past I have read quite a lot to try and understand what was really different. At one time I thought they re-engineered the airframe to make it easier to make (just as Ford did to the Merlin) and improve efficiency. In the end I came to the conclusion it was just re-designated as Vickers did to the Spitfire when they gave it a laminar flow wing i.e. Spiteful. With regards to the proportions of the 152, it is this what attacted me to it. One of the issues with some of the scale 2nd World War fighters, is that the bodies are big realive to the wing area. In addition pre ARTF most scale aircaft were heavy. Difficult to fly especially dead stick. The 152 has proportions similar to a lot of intermediate trainers. It is easy to build light. I am sure that the sucess of the Ripmax Spitfire (brilliant flight charachteristics) is its light weight. I have sen many of these aircraft perform at least as well as a IC plane on Brushless Regards Erfolg

Thought of modding it as a high altitude variant H-1? wingspan was about 47 feet so would be even more like a glider at low altitude I should think, I have a plan file on my HDD somewhere of the long wing variant if you want it mate,prints out in 'Tile Print' at about 5 sheets, The Ta 152 I have modelled is a long wing version, with reduced taper from 0.5 to o.66. I think that is why it is a lot slimmer than the 190, when modelled at a particular scale. As I understand the versions made E-2 High altitude recon/fighter 48ft 7.5" V25 V26 H-0 High altitude fighter H-0/R11 All weather fighter H-1/R11 All weather fighter H-1/R21 All weather fighter H-1/R31 All weather fighter H-2 All weather fighter H-10 Recon. fighter All used same engine, Jumo 213E, 47feet 4.5" wing,different armamant, many just Projects. Regards Erfolg

Terence |I have built a Ta 152H, see picture at the begining of this thread. It was buit with a 36inch span. Why to suit a sppeed 400 with 850, 7 cell nicad. This turned out to be a mistake, with the long nose and a heavy 480 (Kontronics with built in speed controller) evrything else had to go to the rear. It is now undergoing conversion to brushless and lipo, Max CF2212 and about 1000mA battery. The weight distribution is now good, with bags of options for equipment. Also half the weight (thereabouts). It is a model easy to design, although I made a mistake or two. The most obvious is no washout in the wing, in retrospect. Although I have cheated in the wing planform, The 152H is a highly tapered wing, I have reduced this. Used E205 for section. In all other respects the proportions appear to be good: a) Nose about one wing chord b) Tail moment arm about 2.75 chord c) Tail plane area +15% d) Little cross sectional area, relative to wing size e) Nose remarkably streamlined, particularly for a radial radiator, (compares well with Hurricane, Tyhoon etc.) the down side is the tip chord is twice roo chord (hence cheat) You do need to build up the fin, shhet fin does not look right, tried it, then rebuilt. The wing loading is 12.8 oz per foot squared. My model was designed from 1) The Focke-Wulf a Famous German Fighter, Heinz Nowarra 2) War planes of the Third Reich,William Green It is an all sheet (covered) model, doped tissue, sprayed Humbrol finish. I think a 48" version would be ideal, first post novice model, virtually trainer like proportions. I Recently read or heard on TV, that one of the full size wartime)pilots of these aircraft, said it was like flying a glider, in its forgiving nature. Regards Erfolg

I have been having trouble with my Lipo charger and balancer recently. Still no nearer resolving the issues. I have a 450mA (2s), remainder (3s)850mA. 1200mA, 2200mA & 3200mA lipos. Yet my current charger only charges at 1000mA, 1500mA and 2000mA. It seems time for a new charger, with greater versatility. What versatility do I want. I have been thinking and I think this is what ideally I would like. a) Greater range of outputs in mA, ideally infinitely variable (but would this be convenient). b) Must do as a minimum 350mA to 4000mA c) 2, 3, 4S d) A numeric output of what is happening. With the trouble I have been happening I would like some indication what is happening and what has happened. I guess I would then need to understand the information. Any monitoring done, should this be a real time link to the PC, or a transferable file. Although I do like the pug and forget facility of my present device, it does have limitations it would seem. e) The cost should be reasonable. I like most modellers have a draw full of chargers, most of no apparent use, or I do not know what they are supposed to do. Most were not cheap, yet are pretty basic. Any way I do not want more junk for the draw. I seem to remember RCM&E did a comparative review of chargers a few Christmases ago, but do not ember any since. What are others using: 1) Why? 2) Does it do what you want 3) What does it not do 4) What would you buy today Your feed back will be appreciated. Regards Erfolg

John I think you are right or at least valid, in your points. I will be surprised if there is a section created within this forum for old time flyers. David is almost certainly right, at present there is not enough interest. I (to) would like a consolidated forum for old time models, that was sign posted, so that people would find it. Rather knowing or being told by word of mouth, articles etc. of its existence. My experience of old timers is exactly one. With access to a knowledgeable forum some of the disappointment, trauma and expectations could have been managed. Instead I initially had a aircraft that would only do a powered glide to ground or an unmanageable brick (got a more experienced flyer to crash it to confirm, it was a pig). I was advised not to pass the dustbin without depositing the model in it. Yet I finally modified it to fly (quite well). But it has all the limitations you note. A forum may have got me to the same point far quicker. Will I build another, strangely enough I have a free plan for a 52” Mamselle, which I am considering (I to love the shape). The important issue will be what do I expect from the model, and is it possible to realise that concept . Good to read your views John. Erfolg

I have read this thread with interest. I thought that how much down, none or up thrust required, was to do with moments. Taking a forces diagram approach there are a number of forces at work. a) Drag force from wing b) drag force from the body c) Drag force from tail plane d) Drag force from undercarriage e) Drag force from any other element of note f) Rotational forces from the wing and tail plane (due to lift forces) f) Force from propeller If we take moments about a point, we should be able to establish equilibrium conditions. Although many of these forces will vary with speed. I thought that offsetting the thrust line was a practical measure to establish equilibrium and minimise trim changes with varying airspeed. If the engine is positioned at the ideal position, with the other major forces (i.e. wing) it is possible to have the tail plane rigged so that no effective up or down elevator is required or down thrust is necessary irrespective of engine power output (i.e. no trim change with speed). As most of these forces are unknown to us modellers and most are not into mechanics/applied mathematics, a practical approach has been generally adopted. I understood that some rule of thumbs have been established (which ensure all forces/moments are in an acceptable equilibrium) 1) High winger, with engine as part of cabin, down thrust required 2) Low winger, with engine as part of cabin, zero to very possibly slight up thrust required. 3) Mid winger, engine part of cabin, zero up/down thrust required 4) Engine set high, wings in a low type position, lots of up thrust. As with most things, a little understanding of the science helps us to be able to apply the practical solution in a predictive way. Also interpret our observations in some context, to plan the way forward (if what happens is not what we expected). I am sure that one of these German flight groups will have program that that predicts what will happen, for any given configuration and wing section etc. I picked an old magazine up recently to find that 10 years ago one group was using FE for stress analysis and performance prediction in F3b. Regards Erfolg

It is time to brag about my proportional dividers, replesant in a Faux Leather case, with Prussian Blue velvet lining. The instrument itself is brass legs, with I presume is nickel chrome pointers (all shiny) It is graduated for circles, lines, plans & solids. As I drool, my mind trips into the present and I think must throw this antique junk away, to make way for something useful. You do not mention, railway or ships curves, for those grand sweep of line. In the modern world once the outline has been captured, into a vector graphics CAD file, with the touch of a few keys, you can have whatever size you want. Shaky curves are transformed by the Bezier curve function within the package. My one complaint with CAD, is that without a plotter/printer of appropriate size you are at the mercy of the local print shop. I have been quoted £35 and £1.50 for the same print (you have to shop around). I am not anti drafted product but CAD does have a lot to offer. In the same vein I now see models which were considered the province of experts, flying on a regular basis. The construction of these ARTF models is almost always better than the average builder could achieve (due to skill and time). I also agree that model shops need the volume of sales (profits)that these ARTF products bring. Unfortunately not enough to prevent the closure of nearly all the model shops in the City where I live. Hence I have problems obtaining the bits and pieces required for my scratch building. Regards Erfolg Regards Erfolg

I do not intended to decry surgical tubing bungees. They do work, as you suggest it can be possible to stretch them to a greater extent for a given (unit) length. I would contend that there is probably little difference between the two types. I personally prefer the greater initial punch with rubber to get through the first 20-30 feet, then rely on the higher wind speed above ground level, to kite up, or weave to get airspeed up, to re-establish line tension and gain further height. Yet I do not think the differences are worth fighting over. Cotton covered bungees are another thing, the cotton sheath tends to limit the stretch. Their performance is much lower than the other two. On the plus side they have far greater resistance to nicking (grass and stubble) and subsequent breakage than rubber or silicon. It used to be that Silicon tube was the most expensive, followed by solid rubber, with the cotton bungee at the lowest cost. It would be of passing interest to know if things have stayed the same. Regards Erfolg

I am certainly no purist. I do tend to modify plans from as drawn. Sometimes it is to suit the avaiable materials, may be from experience from other people etc. It is the exchange of experience that can breath new life into some of the older designs (also true for the new). As Alistair alludes, their operational range can be a bit limited in the following ways a) Often flown near the stall b) Normally trimmed to fly in lazy circles c) Landings were in the stalled condition (D/Td) d) Flown in lightish winds Models such as Rudder Bug, Radio Queen were some what different. Designed to carry relatively heavy equipment, single channel etc. So generalisations are fraught with caveats. What I would like to see is the exchange of information to make designs viable, For example. 1) Brushless motors, lipos, mini servos, light weight receivers are so light, that getting the model to balance at the CG can be difficult. Without lead in the nose. 2) The dihedral can be excessive when used with modern radio, if Dutch Rolling is to avoided. 3) The wire guage (undercarriage) is possibly a little light for present day landings. Discussions on other peoples experiences and opinions would be helpful I feel. Although I suspect there are not many of us builders (of old/different models) about today. Regards Erfolg

I used to purchase 5/16 square rubber from my local fishing tackle shop. I had to bargin a discounted rate as it was usually sold in short lengths for making catpults for bating. I thought it was superior to surgical tubing as the pull per unit length was greater than surgical tubing. Could be used to launch 120 inch gliders, with little problem in stillish air (surgical tubing could not do this). If you can get surgical tubing in longish lengths, it is easily joined by the dowel and binding method (George Stringwell shows it in his book). But I guess you know that already. Regards Erfolg

Ah Well whats 10^3 between friends Regards Erfolg

I should have written 2.4MHz, not 2.7 an age related aberation. Erfolg