Erfolg
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Posts posted by Erfolg
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Going back to part of the original discussion, from memory, it was accommodating the first Jumbo, that was part of the initiator of the benefits of winglets.
The Jumbo could not initially fly into many majorish airports due to restrictions at gates, taxi ways in addition to hanger issues (maintenance etc). Winglets were postulated as a way of effectively increasing the effective span, to within an agreed desirable future limit on span.
The fashion comment set me thinking. I also thought is as much influenced by the status quo, and expectations. Like many on this site including Dave Burton (Biggles) my studies covered 7 years. On that basis placing much accurately on the time line is questionable. Many of the lecturers in this region (probably else where) were from the aerospace industry, as Duncan Sandy reorganised the companies. Then we had Avro, Fairies, Hawkers, English Electric and many sub contractors Metro-vics, Ferranti.
In this case it was a throw away comment from a lecturer, for interceptor aircraft, that low aspect ratio wings , that were in essence trapezoidal or delta were far superior to elliptical planforms. The structural and roll initial issues were far more important than tip losses, at low angle of attack, and that dog fighting was in the past. At the time not what most people expected. End plates were mentioned in some context, dismissed in most cases, as increasing drag. Yet a few years later I took an exam paper that one question was all about an inverted wing, on a strut, from memory about the forces seen by the strut, from a vehicle at a particular speed. Then these wings in the real world ha end plates. Now the end plate has replaced the strut, for a variety of practical, and regulation reasons
The answer of the evolution of winglets, is not as straight forward as most tend to believe, nor probably how and when they work, dependant what the designer and more importantly the user (customer) wants.
Like many I have seen things come and go out of fashion, such as Coefficient of drag in advertising. Cars now tend not to do 70 with wind noise being an issue, or front end lift, or cross winds being noticeable. Yet the Audi TT needed a spoiler to prevent rear end instability. Just goes to show, you never can tell.
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Much to my surprise, in the recent past I have purchased Birch Type ply from "Hobby World", you know the one, stocks stuff for kids, various niche (is that us) hobbyist.
Does not claim to be Birch, it is the look and feel, that suggests to your experience, this is not light ply. I think my stuff is 3/8" thick, although i think 1/4 " was also available. Pricy for a small amount, but then again cheap, compared to a sheet of the stuff.
Unlike a few, I think that light ply is great, not great for firewalls, great for light structural members, mid-way between balsa an birch types. Helps in managing wight
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Off course winglets work, otherwise we would never see them on full size commercial aircraft. Then again we never seem to see them on military fighter types.
I ask my self, how could both be valid?
I Guess it is due to commercial aircraft essentially traveling within a narrow speed range, in a straight line. Could this also be true of full size gliders between thermals. in a thermal, perhaps not working effectively is not the most important aspect?
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I have a old Micro Mould Bowden Cable, unfortunately It appears to have stickchen, in that the friction is higher than I would like. I feel that this would result in hysteresis on the elevator, on a non consistent return to the central position.
Any ideas of a solution, say a lubricant?
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The book ""Valkyrie the North American XB-70 by Graham M Simons, pub Pen & sword aviation, isbn 184884546-4, on page 141 has a picture immediately prior to the demise 62-0207, has an under surface picture in flight. It shows aa series of what appears to be holes prior to the engines.
Super Cruise equipment is not directly mentioned, as on Concord, I guess it was perceived as a bit of an area of secrecy. Indirectly discussing the system, mainly from the perspective, is it visible. Air was slowed from Mach 3 to I by a series of adjustable internal ramps, plus exhaust doors in the upper surface of the wing immediately Infront of the Engines (to avoid using after-burners, all of the time). Discussed P86-87 amongst other.
There seems a number of excuses to have cheat inlets, and still be semi-scale.
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Simon, I have argued that fans increase the thrust or force, that is by doing work. You get nothing for free, you have to supply energy, the resulting effective work done, depends on various factors.
My only issues are that ducts absorb energy, supplying air from just Infront of the fan, should be more efficient, than a long duct.
I see that you stick to your principles of minimal build weight, to allow lower flight speed, at the expense of robustness and potentially robustness. This is what floats your boat, so why not. I just believe in this particular instance you can/could improve the power system, by a few tweaks (I always know all my models could be better in some respect, ahh, hind sight).
With gliders in particular that the so called lift, term has a V^2 in the relationship. On that basis once the model is at height, not much more velocity is required to achieve a lift value, that is the same as a lighter model, that makes little or no practical difference to duration or distance, the pilot matters generally more. On this basis many favour a robust model, even if the weight is higher than others favour. Epoxy models will often provide robustness and light weight.
Your Philosophy meets your wants and needs.
The mainstream DFs, use power at a rate, that normally results in short flight times, often heat issues of various types
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Simon
We will both agree, that when gliding, lets say a steady state condition, what generally enters the tube is pretty much the same velocity as the model is at.
To get thrust we rely on F=Ma, in essence air density is constant (at a particular time), on that basis the thrust, force comes from accelerating the air the fan sees. Gong back, to our youth, when dong fluidics of a multi element pipe system, if we can introduce an additional lower friction/loss common, a low loss source. The calc changes, with potentially higher thrust, as a additional volume of lower loss fluid being available.
Without resorting to a few calcs being definitive of the why, cheat holes actually work and can work well.
it is a great pity that Dave Burton is not with us, as I strongly believe he would present a better and clearer argument than me.
We also know intuitively that DF are less efficiently than a prop, hence the short flight time, particularly if we try to fly fast. In essence we can easily show the relationships between Work Done etc and ducted systems, yet for most people, they just know from observation.
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In my case I believe it is the short staple length that is the result of using recycled paper. There is also potentially an issue in that with some virgin tissues, the composition/source of the feed, is carefully controlled, particularly in the case of Japanese tissue (the type that is suggested contains Bamboo). Where the recycled green material. is what what it is, a mixture of, who knows what.
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Using laminating film, is generally not a problem. Unless, that is, you are going over Depron or foam board. Then the issue is the high heat, I use to shrink, is not compatible, with the polystyrene.
The only problem I have had recently is with "Tissue", in this case of recycled, green tissue, my results looked like your photo. It is my intention to dump these sheets, as not suitable for my needs.
I will be purchasing something claiming to be Modelspan, or similar. If my other stocks are questionable, I have no MS near me anymore, so it is online purchases. I suspect it was a Amazon purchase that is my resent issue, although I cannot be certain. My purchase will be either a specialist FF garage type seller, or perhaps Leeds, now that Webbies have closed.
I also tend now to use WBV, either Ronseal Hardglaze, Wickes WMV. I do tins of MHG of dope
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I use an Ender 3. Most issues are me.
I rely on this forum, and club members mostly related to Fusion and Ultimaker.
With the Ender, it has been release issues or non adherence when starting a print. I bought a glass platen, which does not work for me, I have since purchased some stick on print surfaces, these work well, as the original platen do not seem to be available.
You will be surprised how many items I have designed made and used. I have 3 cards now full, now on my 4th..
All the problems relate to me
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This model is covered with laminating film, then tissue covered. It worked very well, no wrinkling.
However I recently tried the same approach on another model, there were wrinkles. I have come to the conclusion, I tried recycled tissue, the staple is much shorter than old, traditional tissue, this seems to cause the wrinkles. The problem is there just using tissue over balsa, a case that saving the planet comes at a cost.
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I think I must misunderstood what you have written.
Any way, in contrast to the approach (Physics)we were required to adopt, at work, entered into the design file. I now generally adopt intuition, relying on academic training ,only on calcs if really desperate or pretty bored.
considering duct shape, we all recognise (from fluidics) that a circular duct is better than say an extreme letter box shape in most circumstances, for the same unit area. The losses tending to be lower. That is other than say an outlet, where Bernoulli (conservation of energy) suggests that the mass flow, can be traded at an outlet for increased velocity and pressure. So the round duct is good, other shapes not as good.
With respect to the length of any containment, we will have observed that a long hose pipe that at the discharge point, the flow an available pressure is often much lower than a short hose. Often this observation goes along with noting a coiled pipe is poorer than a straight pipe, which suggesters that changes in direction, shape transitions in direction, cross section, are all unwanted. This is all based on a unit feed. Long transmission pipes are not the best.
Most of us as kids have played with tap flow, noting that at low discharge rates, the flow can be laminar. Increase the flow and it becomes turbulent. Although many text books show this laminar flow, with zero (stagnant) flow at the wall of a surface, with increasing flow velocity at distances away from the surface. The real world experience is most often not the case. I reality there is a stagnant boundary layer, which quickly becomes a chaotic turbulent flow. any imperfection, even dust can initiate this condition. All of this is associated with losses, per unit length.
Again relying on our friend Bernoulli it matters little where the fan is on a single dimension duct. However introduce an additional inlet, things change. Particularly if the inlet is near the discharge point, even better if a Plenum chamber can be arranged in front of the fan unit (in this case) and a short discharge pipe.
I would like to claim I have put these concepts into practice, to date, I have failed. My He 162 so far is a failure, being to heavy, although the short ducting 3d printed works well. I am now looking to compromise more, with a 3d printed plenum chamber at the front and a short 3d exhaust with a 3dprined outer shell. To gain experience I am building a TN A10, although the wing loading disturbs me.
It is interesting that there a good few doors in the XB 70, outlet doors. Just like Concord, these were to facilitate, super cruising above the speed of sound. IMO a so called cheat inlet, is pretty near to scale (different purpose), with the DF right at the back. I am sure that you could minimise the losses from the chaos of the additional fluid.
I am not sure that the ducting is required between the rect inlet to the fan (other than, are they structural). The increase in area, would potentially drop the air (fluid) velocity dramatically, reducing (potentially) losses.
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It seems that I am not the only club member who has not been to our field site since before Christmas. However down at the club indoor social meeting, it was a different matter.
Our Chairman had organised a build and fly, chuck glider competition. Build materials were supplied in the form of Depron, balsa, bamboo skewers, card material, disposable craft scalpels, cutting mats and Cyno. Pretty comprehensive I thought.
you may be thinking how did you get on building didn't. Why, indecisive and an aversion to Cyno.
How did the comp go, well, some one won, then there was the 20 or so losers. Observing the models and their results, there was no clear, yes, that is the way to go, a sure winner. Separated by fractions of a second, so it appeared.
All to soon, due to the Icey and freezing conditions members departed for home. I finished my pint, made my way to the car, switched on the windscreen, rear screen, heated seat and waited for the car to prepare itself, before heading home.
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Simon, it seems that you have moved to commercial fan units?
With such long ducts, a couple of cheat holes could/would improve thrust even more? From the I have material cheat heat holes would not be out of place, as close up, it was/is (the remaining example), has many panels etc
I have also considered the NA XB70, in Depron. I now have a couple of books on the XB70, I was so enthused.
You certainly do better than myself, as I have abandoned a He 162, as my foam board and 3d printing seems to heavy. Particularly when compared to the commercial foam BAE hawk and hawkish look alikes.
I do fly a Depron Delta, glass covered that flies exceptional well, (although the twin fin and motor flew better still). The original Depron was much better, cutting much crisper and stiffer.
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It is a paradox, that as glider/power launch assist gliders have achieved a level of performance that was unachievable back in the 70's, the numbers who enter competitions is now tiny compared to the days of BARCS.
I am nor sure it is price, as I see many of the types, flown by club members.
Some time back a comparative evaluation of a 2m glass moulded model was made against my 2m Sagitta (a good comp model of the 70's). It was just like comparing an Austin 7 against Porsche.
Enjoy, looks like hours of joy.
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The great thing about many hobbies, including ours, there are many positive aspects.
Many of us enjoy chats at the field, putting our world to rights. I enjoy my models often just floating about, others are into the aerobatics, others the discipline of scale type routines. I just like seeing my models flying, not complicated.
Personally I like building, yet have a couple foamies, a Albatross Dva, Dornier 335, as they fly well, often in spite of me.
I will now confess to flying(or is it gyrating) a BMFA simple sort of triangular or is a roboid model, covered in laminating film(should be with the tissue paper supplied) in the (back) garden, much to my wife's amusement, last week. She did ask is it flying, or is it the rubber band that keeps it roughly up?
I am now looking through the door windows at the rain lashing down, the trees going this way, then that way. Amazed that the Gulls keep soar along the roof lines, I can see a Magpie surveying the world. It will soon be another year, yet even this weather has its own beauty, and the World continues to rotate.
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It is my view that the safety issue is dominant when working with Lipos. IMO probably true for most batteries, be they Nimh , Nicad, or Pb, whatever.
Even 6s where the costs tend to be noticeable, if something does not go to plan the cost, be physical, cost, inconvenience, are far to high.
From a ex Project Manager whose view was, our task is not to be safe, it is to do something, whilst being safe. At a practical, we all want to finish work uninjured, an accident has a impact on the program that is not advantageous, there is a financial implication that is negative, due to reporting, often diverting resources, without considering potential legal consequences. IMO this all holds true to messing with Lipos.
Bizarrely i have seen a nail driven through a Lipo, when nothing really happened. This seems the exception that proves the rule, some people are lucky, you may not be.
I see messing with Lipos as potentially so negative, to be a no brainer. Which often has been the same with batteries in general, the right equipment and training are necessary, no place for ad-hocking.
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I will immediately confess that I have not flown a model from before Christmas. A number of reasons, one , the weather, two going to Germany, third illness, the forth I cannot be bothered right now.
When I did go flying, it was perhaps a few days after engine tests and range checking a old DB Mascot. In truth my wife threw me out, telling me that there is no wind, it's not raining and you are in the way.
A day or tow before we had received a booklet through the post about the routing of the imminent inter connector to the wind turbines out at sea. A drilling platform has been out at sea, on the horizon, with no sign as yet of ay windmills. So now driving along the new or replacement Moss road. I reflected well, I now know it is going to to the south bank of the Ribble, close to Preston. My guess that the interconnector would head east to an existing sub station (serving the local farms) was wrong. I was thinking about what impact all this will have on the wild life , particularly birds. As I am guessing that a lot of building will follow. Makes me sad.
I arriving at the field thinking the gate is unlocked, someone else is at the field. After trundling down the trac, sliding though the mud from the farmers (probably contractor), turning into the field to find a locked gate, with no sign of any one else.
Being here, I finally decided to fly, although very miserable weather. I just picked out my Canard and launched. It was well out of trim, in pitch, God Only Knows why. The flight was rather problematical, in thet the model was always a dark, featureless black blob, against a very dark sky. Not a pleasant enjoyable experience. Next up was my reduced scale, slightly modified "Nobler" originally a famous CL by a George Aldred. As a model, not a versatile RC model, as you would expect it does not roll well, nor does the rudder work well. However it loops well, tracks well, and is stable in all axis. As to flying, the weather was the same, and flying was still miserable.
No one came, Billy No Mates.
Getting back up the track, reaching the lane, I heard all the chunks of mud flying of the wheels, against the car. I am now thinking, I will have to power wash all the mud of again, at home.
I have not contemplated flying again, although having paid my Club fees and BMFA etc.
Two other things, I came across three RC Aircraft (one jet) magazines in Germany and a Model train Model shop with actually thousands of (toy) trains in all scales. Is modelling doing better in other countries than the UK?
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yep, I have also clocked the CG issue, now.
Often a problem in this electric era, gone has the heavy Glo engine and its gallon of fuel. Even small diesel and thimble of fuel, often was on par with the electric set up.
Another issue is that FF models were set up very differently to current RC models, much more is also expected from RC models today.
Very nice model build, a credit to the builder.
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I do not think I have any deviation of opinion of the previous posts.
From my own experiences, definitive rules leading the determinant results, do not seem to exist.
I have purchased really, really expensive Lipos that have lasted, not for long. I have also purchased very cheap (HK) batteries that lasted for years of continuous use. Yet others with the same brands have been at the other end of the scale.
What I have noticed, that barrel like Lipos are past there best. The ability to deliver power does reduce with use. The voltage will be there, even the ampage will often measure as OK, the ability to deliver power, another story.
I have found that the internal resistance gives the true state of the Lipo. More often than not, one cell has acquired thigh resistance, the others will also have increased with time, but it is that one, drat cell that is the crux of the problem.
I have read that one significant reason of putting Lipos into storage mode, is to circumvent some of potential vagaries of allowing the capacity to attenuate whilst not in use, is more to do what could happen in storage. That is very cold or hot conditions, which our batteries generally do not like. I have been told that why increasingly the cell separators are now thicker, it helps in ensuring a better operating temperature.
At the end of the day I rely on on what I read and have been told and what seems reasonable, as I do not really know, with any certainty. I just remember the days of multiple explanations of "Black Wire" phenomena, now most of us now believe that it was due to cell venting, due to basic chargers and how we were recommended to charge.
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I do like the diversity of the "who has been flying", IMO there is much more to model flying, than a few pictures of superb models, perhaps that is why I never post a picture of my models complete with "patina".
My flying starts much before switching on the RX, the vagaries of calcitrant model of a flight are far more interesting, than a perfecting behaving a RTF.
So IMO leave things as they are, less boring stories of perfection, this is the Real World.
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Many seem to be in denial with respect to the present and future challenges facing the hobby. As it seems to be said in this era "things are as they are, suck it up".
The realty is that increased restriction's and requirements will put of some of, be they young and the old. Particularly if thinking along the lines, I fancy a go at that, with no experience of the hobby recently. Those of us in the hobby do just suck it up, although the restrictions have an effect on what I do. I no longer can go on the beach and fly a model, amongst other things, yep I suck it up. Those considering having a go, in some cases will not have a go, it may be a handful, ideally we need to avoid this handful increasing in number.
The £2 pound increase is not a deal braker for me, it could be for some, when all the costs are amalgamated,. Death is my main worry, at present, it is the problem with an aging and skewered norm to the right.
Our numbers are no longer what they were, cumulative spend is not what it was. The big expensive models sold, are not the weekly spend, mainly the pre retirement modeller, it seems not enough to keep the LMS going. I have seen many attempts to get the young into and staying in the hobby, it mainly seems to be middle aged that are coming in.
You may be thinking I am opposed to any increases however small or large. My concerns is about managing the future opportunities and threats to the hobby, which includes all fees, regulations, costs and so on. I do not dismiss those who have concerns about any increases or changes, many others will not be bothered whatever, they all matter.
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The Ender build plates arrived today. It could have been really bad news, the courier folded the package in half, then pushed the envelope through the letter box. Luckly the spring steel just "sucked it up" becoming flat when opened up.
As a replacement for the V1 bed plate, not quite perfect, being much thinner than the original bed plate. This difference results in very light spring pressure when levelling. In operation the slight vibration can result in the levelling wheels moving. Later I will take the assembly of the table and put some washers under the springs as spacers, to provide a increased spring load.
In operation, I am printing again, success.
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In some respects all reactions are normal. Yes, compared with many or at least some sports/hobbies, the fees are not bad. Then again, some sports/hobbies/ interests do not cost as much up front, and or many others are lower costs, my wife's Golf and Bowls are examples of both extremes. The local Cricket club is in the middle (I am to old, and useless for cricket).
I do our weekly shop, and have noted that increasingly people of my age group are counting the pennies (heart breaking), many modellers are of my age group. Not only do we die, more are becoming under financial stress. It cannot be taken for granted that the money will be found. With younger people, it possibly will be the CAA requirements that could act as an obstacle to entering the hobby, not just money.
The apparent reduction of the larger hobby retailers and distributers, also tells me that the hobby in general cannot take it for granted, that money will be found, to spend on our hobby.
A10
in Tony Nijhuis plan builders
Posted
I am coming towards the end of the build.
I have a number of questions with respect to
I have now set the model up all the equipment and dummy Lipo to access the Cg movement with various layouts. It moves about 12mm.