Simon Wright

Very nice, I need to learn more about building with Depron.

The point I was making on calculation is that, for model aviation it is so full of funny factors and margins as to become almost useless. Calculations using wood and adhesives are easy, values and factors for the allowable stresses of wood are readily available, the information is published in various locations for most woods and densities, as are the jointing factors for adhesives. Unfortunately the spruce/balsa/ply we use is of inconsistent quality and ungraded. Calculations for our typical wings with I or C beam spars , boxed with D sheeting tend to ignore the monocoque formed instead focusing on the spars and shear webbing. this builds in another margin for error and over sizing. The comments on high technology wing sections (aerofoils) raises another topic that leaves me smiling, which is the ability of the average or even highly skilled modeller to achieve a micron perfect section with a knife and sanding block. If the section is close there are very few aerofoils that allow for the sag of covering between wing bays. CNC moulds and composite wings anyone? Regarding the theory of aerodynamics and mechanical engineering I have a Degree of knowledge in both and while neither a structural or FEA engineer have a good grasp on the  complex interactions, maths and forces involved.  Basically if you build it and it flys without breaking up is it safe, and would some numbers on a piece of paper make it any safer?       Edited By Simon Wright on 26/09/2016 20:44:41

A question raised elsewhere on this forum made me reconsider an old favourite of mine regarding design of model aircraft. Namely does anyone in this hobby really design anything other than by size and shape, the mechanical and aerodynamic stuff that is. The design of the aesthetic or a beautiful shape is an art or skill that few can aspire too and not part of my rambling. My own experience of designing a large model by calculation from root principles soon foundered when I started following Rule Of Thumb (ROT) techniques. These ROT’s combined with a plethora of estimated figures for material strength, joint and other funny factors very quickly made the precision of calculated figures irrelevant and the accuracy questionable. Precision figures for Cd, Cl, Cm on aerofoils are similarly based in perfect space and are fudged to realise actual conditions. Even calculating Vmin & Vmax, the prime inputs to any strength calculation is full of little 10% margins and deductions. My latest radio has the benefit of telemetry and I intend to test out the accuracy of a few theoretical calculations, even here the accuracy of the instrumentation imparts yet more deviations. Thankfully with small mass, limited size (moment arms) and minimal payload requirement we can easily carry massive overdesign factors between 2 and 10 maybe even more. Other than providing some reassurance by numbers, design by calculation seems to be a pretty fruitless exercise compared to the alternative. I feel that Empirical design is more the norm using ‘That looks About Right’ (TLAR) techniques with a little bit of copy and paste and a bucketful of ROTs. If successful model ‘A’ has a wing area XX, tail moment YY and tail area ZZ changing the outline shapes should have very little effect on model ‘B’. Similarly construction techniques tend to follow monkey see monkey do principles with material sizes, D boxes and structures following methods experienced or seen on similar design. There is nothing wrong with this technique but it can and does lead to failure when pushing the limits of personal knowledge, materials and technology. So, after my little ramble are you an estimating mathematician or a very capable mimic.

I know it's shocking, and lets not start on the questions about what we get with full cream, semi skimmed and skimmed. Si PS : What is organic milk?

I like the turbine Cri-Cri for $25000. 140 knots but only 70 miles range.

My wife and kids call me a grumpy sod too. Discussion fora such as this are a great way to share knowledge and express opinions. There are neither right nor wrong opinions. I do feel however that any statements or opinions expressed should be capable of at least gentle scrutiny. So back to the o/p about oversized models and the 'opinions’ expressed thereafter, what, if anything do the people claiming its down to Ego, Deep pockets, one upmanship, stupidity and incompetence want to see changed? Should there be a limit on how much a model costs, more regulation based on size, weight, volume, etc. Should separation distances be updated and enforced at clubs and shows. Should there be a ban on anything new? It is okay to moan and whinge about ‘stuff’ just don’t negatively tag and label people doing stuff you don’t, forcing yourself into a ‘them and us’ mindset. If you think someone is doing something unsafe or bad for our hobby take time to think it through and tell people your thoughts on what is needed to improve it. If your idea is good, it could gain mass and end up being adopted by those that allegedly represent us/ If you can’t be bothered to fix the problems I am afraid that we are all just Grumpy old sods moaning about the price of milk!

Not too sure what the OP wanted from this discussion, I have not read all the way though the thread but find myself more than disappointed by some of the posts that I read. With only about around 40k model aircraft enthusiasts in the UK we are already a minority group and don’t need to further fractionalise our hobby/sport. After 25 years of building and flying all types of models I too have found myself gravitating to ever larger models. My fleet ranges from heavyweight 90g F3p to 120cc 3D models. I am currently researching and saving for a 170cc 42% model. This is not down to EGO, a fat wallet or any of the other demeaning comments made. Instead it is the continuation of my journey to find the model that suits my personal needs best. Cost: What does it matter what any hobbyist spends on their hobby. We each have budgets to live by and should not decry those that spend more or less than us. Some lucky folk have huge budgets to buy what they want when they want it. Others spend years building a model to spread the cost, while others buy dozens of models over a year which could fund what they perceive as an expensive model! I will not even touch on modellers who pursue competitive RC flying in its many forms as their commitment in time and money typically reaches a whole new level. Fun per £ and satisfaction. A great and fairly easy concept, but again marred by our individual preferences and circumstances. , I find that small foamie electrics and 40 sportsters/funflys deliver the best fun or laughs per pound spent. I can have a lot of fun and really do not worry too much if I pile them in. They are a quick fix or instant high, they do not however give me any great feeling of satisfaction. For satisfaction I look to my large scale aerobatic models and the pursuit of a perfect flight. Each modeller gains satisfaction from different aspects of the hobby. Each to their own . EGO: A most insulting term used here to describe those that want or have something another does not. It is human nature to strive for more or better, I could live in a rented 2 berth touring caravan on a farmers field but choose to live in bricks and mortar on my own little piece of land. Is that EGO or personal preference? Seems like sour grapes from where I am.. Safety and large model crashes: mega models (Over 20kg) are regulated and controlled way more than our average models, both the build and flight performance is witnessed and inspected with further checks required after any change or modification. There are limits on what can be classed as a model aircraft which limit the AUW and size, after that point you could still do it RC but would have to follow full size practice. In summary, if you are happy floating around with a Bixler, or tearing up the sky with a 120 sized spitfire please continue to do so and most of all have fun. If others want something different, don’t berate or insult them but rather enjoy the diversity available in this hobby.

I have never given up on glow, I fly electric and petrol too and find each to have an optimum size. For little chuck around models there is nothing to beat electric upto 2200 3s sizes. I have tried 6s to 12s electrics but the investment in equipment, batteries and power supplies is not rewarded with duration, performance or enough flights in a day. I fly petrol models at 50cc and above where the extra weight of an ignition unit and battery is barely noticeable and glow would be a no- go at these larger sizes anyway. the convenience of a liquid fuel over electrons comes in speed to refill with the same gallon of 40:1 being suitable for all my planes. I personally find petrol below 30cc to be disappointing. Glow power reigns in the 40 to 120 sizes, it is quick to fuel, easy starting and depending on tank size can provide plenty of duration. My largest glows are a 180 FS and a Moki210. Both run brilliantly and are surprisingly frugal. I do love my little OS10 and 15s too but they are run more for novelty than performance reasons. If it pulls a plane around the sky I am willing to give most anything a try. Glow dead? I don,t think so!.

So where is the best to buy new balsa from. I know of SLEC, Balsa Cabin and Inwoods. is it all of similar quality or is there a best brand?

on special... http://www.inwoodmodels.com/index.php?id_product=6767&controller=product

I had one way back when as my first IC trainer. ( I learned to fly on the Electra-Fly sp600, 8x4 and 7 x sc1700) Fitted with an OS15FP, remember that it was unable to ROG in my hands but I solo launched it okay and it flew fine, although I had no baseline to measure against.

No point arguing unless you can sort of prove less than 28 days use. Alternative activity 1 acre in a 30 acre field (shared use still requires Planning Permission). which would be classed as COU.

Posted by stu knowles on 17/10/2015 23:01:40: just crack on and keep your head down. You will need PP if someone comes along and says so, (which is only likely to happen if someone objects to what you are doing. Don't poke a sleeping tiger Have to agree. Planning law is quite clear that using for an alternative activity for more than 28 days per year requires PP. Better to just get on and fly as and when, keep quiet in every sense of the word and only apply for retrospective permission if the planning officers come knocking at your door. It is the way that the vast majority of clubs operate.   Edited By Simon Wright on 17/10/2015 23:53:46

Zimmermann, KS, JMB or MTW are in my opinion the best. https://www.youtube.com/watch?time_continue=72&v=8klnH1vLHbc

I fly DLE, not because of any brand loyalty, just because they are cheap, reliable and spares (if ever required) can be sourced cheaply and quickly off the internet. My DLE111 is now 5 years old and other than an ignition and carb rebuild kit has been faultless. Me, I would go for the DLE61, 10% larger capacity and I think it is lighter too. Easier to sort a header for the side exhaust engines. If I had spare cash I wouldnt hesitate to give the DA60 or MVVS58 a go.