Electrifying free plan models

[kc]

Swiss flyer kindly asked if I understood his reply.
Actually I dont!  There are so many unknown variables in model flying, that I cannot see calculations being much use and certainly no better than the ‘rule of thumb’ estimates the rest of us use.  I cannot quite see how the 65 mph figure was calculated or what use it is.  Probably it is derived from the RPM multiplied by the possible amount the 6 pitch prop should move forward per rev.  However every experienced flier knows that different makes of prop vary widely at the same nominal size, sometimes by an entire size.  Also that glow engines seem to ‘unload’ when in the air.  Then the same engine and prop could be mounted in a Spitfire with retracts or a triplane with huge radial cowl and much greater drag.  Not to mention downwind or into the wind or high nitro fuel etc!  Then again we dont really know what speeds our models achieve because nobody ( except Peter and select few ) use telemetry (yet)
As for stall speed we dont know what speed the model is doing so we cannot  deduce when it stalls from that,  but even if we could the estimate was so far out the model would have crashed long before!
Again it is an ‘urban legend’ that big models fly better than small and it is certain that scaling down changes the characteristics so drastically sometimes that the same shape is unflyable ( see Keith Mitchells article about the Miles Hawk or Magister ) Where in your calculations does the factor change for smaller or larger models?

So I much prefer to rely on Rule of Thumb for engine sizes.  I figure that if it works for someone else it will work for me!  The rule of thumb idea that 100 watts / pound is needed for aerobatic models and more for super performance may be correct, but I have a suspicion that the Extra and Sukoi I have mentioned earlier were using a lot less power per pound  yet give fine performance.  Therefore I asked what other people actually used. Maybe the spreadsheet will eventually reveal the information I need.

I am intrigued by the idea of the Swiss using robots to clean their premises and having trained engineers recharge them every three hours!.  Why can’t they just employ illegal immigrants to do their cleaning like the rich do in Britain?   Could it be that if you base the aid agencies in your country you get the opportunity to send the refugees to every other country but your own.  Hence no housing problems and no cheap labour in Watch & Chocolate land but a need for robots. Clever!

Mark. I do appreciate your efforts to help me and I hope you will read this in the correct spirit, hence the British humour to see if you still retain the proper British sense of humour.

P.S.  Excuse the delay in reply but I had to go to the library for engineering books to look up what the " shear range " quoted by Erfolg actually meant.  Was it some tearing of metal, fatigue caused maybe by centrifugal force that affected the material  in electric motors but not IC?   Nothing in any engineering book.  So I asked an engineer but he was a bit dyslexic and read it as ‘sheer’ ………Oh, it’s just a typographical inexactitude.

Edited By kc on 29/10/2010 11:38:25

[Peter Miller]

You know,  what I think that I am seeing here is a remarkable example of

 

Male Bovine By Product Baffles Brains.

Edited By Peter Miller on 29/10/2010 11:42:40

[Erfolg]

KC

 

I am not sure if it was a tongue in cheek joke.

 

By shear range, I meant there is a very large number of motor models produced.

 

By example, the same armature and magnet arrangements will often be offered in various wind numbers and terminations, star or delta. Which all help in determining Kv. This one apparently identical motor having several variants. Increasing the numbers still further, a broadly identical motors, sometimes come in differing armature lengths, again these will often be offered in different winds. So from one basic design many variants will often be available.

 

If you consider the number of motor ranges and the derivatives, the variety is vast.

 

This is not so with IC engines, from one basic casting it may be possible to get, perhaps two motor sizes, possibly two motor variants per size. May be 4 models. Electric motors often being 10 or more models from the same basic configuration.

 

If you then offer different number of magnets, change the dia of armature, change the number of teeth, wow, yet more variation.

 

And they can all look much the same!

 

So not an engineering term, meaning there are an awful lot motors available, compared with IC.  Which are not necessarily obviously different, yet materially are.

 

 

[kc]

Erfolg,

Of course it was a joke!  But its 'sheer'  not shear in your context! 

 

[Swissflyer]

Hello KC,

Thanks for your splendid reply, it made me chuckle for the rest of Friday afternoon.

And frankly it was an afternoon that needed some chuckles! Not to say a week¨.

Since you didn’t understand my mail, I will also gracefully go to the bottom of the “communication skills” class.

I passed by home picked up your message & went to the post office to pick up a Hornby Flying Scot Electric Train ordered by my son (maybe I should say Hornby “not IC powered” train)

Then I went to the garden centre to pick up a leaf blower to clear the autumn leaves. I had my eye on a £79.99 blower with a very nice 31cc IC motor inside it. One can do interesting things with a motor like that, and it had a guaranteed pitch speed of 230km/hr! Mindful of your wise counsel, I asked the guy in the shop how he knows it is 230km/hr – he looked at me in a steely way and said (in Switzerland) 230km/hr is 230km/hr – he sounded like a Swiss policeman handing out a speeding fine. Except they add decimal points after the 230.

My luck was out, my wife deemed that we should have an electric blower 2’300W but only 180km/hr pitch speed and only £29.99. Ye Gods, me trying to buy an IC motor and having to buy electric!

I began to imagine an electric control liner with a 2’300W electric engine, but I can’t afford enough illegal immigrants to all hold the control handle at the same time and keep the beast in one place.

I needed your chuckles because it was a bad week for flying. We had 4 days of blue sky, sun & no wind. The flying field below is just 70yds from my front door so all should have been perfect but the temperature was 4deg C. So after 5 minutes of flight my LiPos reached ambient temperature, stopped delivering Watts, and dumped my models back on the ground, after warming the batteries they would deliver for another 5 minutes. Oh for IC, but the building on the right of my photo is a church (will post later)

So winter flying is going to need an IC model I thought about converting my hack, electric aerobat to IC – someone has to go first. I was thinking about putting the following post on an IC forum but maybe KC, you could help me with a few edits before I do?

Hi Guys (I think you are supposed to start that way)

I have seen the dark and would like to come back to the light side.

I am trying to convert my electric hack flyer to IC and am having some problems.

I went in a shop and asked the guy for an AXI Double Codswallop 24, I asked for one of those because a nice chap on the forum, who won’t touch anything that doesn’t roar and belch blue smoke, talked about it, so it had to be a good IC engine.

The guy in the shop looked at me like I was bananas and said I need Irvvin or SC. Now I thought he was bananas because Irving was a composer, so SC sounded a better choice.

I told the guy I wanted an IC engine not an SC engine, he said SC is IC, so I said “I See” but I didn’t really see because my head was beginning to buzz.

So I said “If SC is IC why don’t they call it IC?” I got another “bananas” stare & decided to give the guy my credit card while I was still in one piece.

Anyway I got this “SC 12 ABC” home (I like the ABC bit, it made me confident the guys who built it have got educashun, although I don’t quite know what it is supposed to mean, I expect there is a hidden meaning that some clever IC (not DC) person can tell me).

I hid the fuel (it was a bit stinky) in the garden shed and labelled it “lawn mower oil” so the missus won’t go bananas like everyone else in the IC, or is it SC, business? And could someone tell me what the 12 in SC 12 means because everything else about that SC ABC is in mm?

Anyway, I waited a few days until the missus and all the neighbours for 100 yds on either side were out and tried to get the SC going in the garden shed. I gave it fuel, connected those wires to the top and nothing happened. I was confused as all my electric motors start when I connect them up but this SC thing just sits there.

Then I had a good idea, I connected it to my power drill and soon had it spinning and spluttering nicely, it even began to make a noise like some of those films I have seen on the internet (no not those films).

But then I got more confused because when I stopped spinning it with the electric drill it stopped. So I got more confused as I can’t fly my model around with a power drill attached and anyway the drill seems to be in the place I should put the propeller.

That’s another funny thing, someone told me I have to put a propeller on to make it work. Now I see, or is it IC, even less. My car engine doesn’t need a propeller to make it work and nor does my IC lawn mower.

Is it true that these ABC IC SC thingy’s can’t work without a prop? All my electric motors run beautifully with nothing at all.

And if I put a prop on, how will I know it’s the right one?

So please could someone help my conversion from electric to IC by putting me straight on the points outlined above?

Thanks from an electric flyer trying to go straight.

[Steve W-O]

Posted by Swissflyer on 31/10/2010 15:13:14:

Hello KC,

Thanks for your splendid reply, it made me chuckle for the rest of Friday afternoon.

And frankly it was an afternoon that needed some chuckles! Not to say a week¨.

Since you didn’t understand my mail, I will also gracefully go to the bottom of the “communication skills” class.

I passed by home picked up your message & went to the post office to pick up a Hornby Flying Scot Electric Train ordered by my son (maybe I should say Hornby “not IC powered” train)...............................................................

 

..................................................................

Thanks from an electric flyer trying to go straight.

 

 

 

 

 

 

 

Very good.

 

Afraid the previous "humour" escaped me  ( I guess it is like being Cornish, if you weren't born there and lived there for 75 of your 71 years, you're not Cornish)  but I really enjoyed this, top marks for communication and humour !!!

[kc]

Have you ever wished you hadn't started something?  This is the time I have that feeling!

 

 

As I understand it Swissflyer is asking me to advise on  whether an Irvine or a  SC12 will be adequate IC power for  a Hornby train.  Well actually I would advise throwing the electric motor out and replacing it with a clockwork wind up motor.  My clockwork Hornby train is still working after 58 years and of course its  GREEN .  Driven by Mandraulic power

  I strongly advise you to also buy a Mandraulic leaf remover, its nearly silent, green and much cheaper.  You only have to decide on what width is needed. Transport for your mother in law too.  Especially tonight.

 

Back to being serious!

Perhaps you should define 'pitch speed' for me.  Do you mean tip speed?

 

 

 

[Erfolg]

KC

 

Ah, I see now.

 

 

[DH 82A]

   "   Pitch speed "  is the theoretical airspeed of the model in MPH, according to the pitch of the prop, and the RPM.

 

   It is calculated thus--  RPM  X  PITCH (in inches)  divided by  1056 = MPH  airspeed.

 

     So, a  10 x  6  prop at   10000  rpm =  56.8  MPH.

[Swissflyer]

KC,

It’s blowing a gale and raining buckets here, so no flying & you got the fallout

I had fun writing to you & doing your British humour test, thanks for the good natured & friendly challenge.

Mark

[Peter Miller]

Now I understand why the Swiss are so well known for Cuckoo Clocks. 

[Swissflyer]

Posted by Peter Miller on 31/10/2010 18:58:02:

Now I understand why the Swiss are so well known for Cuckoo Clocks. 

Whoops, Orson Wells made that mistake too. Cuckoo clocks are from Germany, let’s not upset them

Mark

 

[kc]

Well no Navy, no Swiss language, no taxes, no transparency in financial affairs, now they dont make Cuckoo clocks!  Next you will tell us they dont make rolls or army knives..

[Peter Miller]

Being lumped with Orson Wells can't be all bad.

 

I don't know about rolls but I do know that my Swiss Army knife is one of the best tools that I ever bought. IT lives in my poc ket, even if I do tend to lean to the right.

[Erfolg]

Of course they still have a machine tool and manufacturing industry Maag, Brown Boveri.

 

Rather than deride the multiple languages, rejoice at the multicultural use of language and communities.

 

Also a true democracy, where referendum decide big issues. Rather than a politician ignoring the populace view and saying they voted (contrary to popular opinion) as an act of conscience on your behalf, and it is democracy as they represented you!

 

[kc]

If we are being serious I would point out that we in Britain have never voted democratically for multiculturism.  And this thread did not deride multiple languages!

 

But we are not being serious we are just ensuring Swissflyer has not lost his British sense of humour whilst living in a tax haven.  He may need his sense of humour when he returns to Britain in old age and finds the Welfare State has disappeared just when he needs it!

[Steve W-O]

Posted by kc on 19/10/2010 11:51:36:
Would anyone care to suggest suitable motors and LiPo for any of the free plan models designed by Peter Miller recently such as


48 inch Lil Mustang          468sq in   4lb 0oz
51 inch Miss Lizzy            490sq in   4lb 1 oz
53inch CAP21                   477sq in   4lb 3oz
52 inch Werewolf              520 sq in  4lb 5 oz
48 inch Midget Mustang    475 sq in  4lb 12oz
56inch Bootlace                 510sq in   5lb 0oz

All RCME designs over the last few years except Lil Mustang which is from RCMW.  All the weights are Peter Millers own prototype models and he says they are as light as possible, but of course they are built for glow engines at this weight.  So maybe just a little scope for lightening..

I would be interested to know what motors could be used from those currently available from GiantCod, Overlander etc

 

 

Occurred to me this morning, this could well be a non-question.

 

I assume that the glow engine size is known from the title.

 

Turnigy make a "G" series of motors, especially suited to the type of answer that seem to be needed throughout this thread.

 

A G35 is a direct replacement FOR  35 GLOW, A g60 FOR A 60 SIZE GLOW, A g160 FOR A 160 SIZE GLOW ETC (why don't forums software ever have case convert feature)

 

 

They give the prop size range, the cell count range for Lipos, and max current, so there's not much left to decide on.

[Swissflyer]

Being lumped with Orson Wells can't be all bad.

Peter I am glad you picked up the implied compliment, in the model aeroplane world I do accord you the stature of Mr Wells in his.

Your reference to the steel quality in a genuine Swiss Army knife is pertinent.

Yes, in the German speaking part of this country the engineering culture is strong and valued. The commodity steels, textiles (and many other products) were abandoned to Asia many years ago but the top grade specialty stuff is still done here.

When I qualified as an engineer (a long time ago) engineering in the UK was low status, low pay, they told me that anyone with half a brain should go and work in the “City”. Pity is a lot of people with “half brains” did just that.

The German peoples were suspicious of the Anglo-Saxon tricks for creating money out of thin air and stuck to quality engineering. So they bought our leading automobile brands and have the strongest economy in Europe today (see the statistical pages of the Economist). Contrast that with the current UK austerity programme.

I find the bankruptcy of UK political values painful to observe, Erfolg’s comments are well placed.

KC

Please never accept a job here thinking your salary is tax free. You will immediately discover that about 10-12% is deducted for a minimal social security system, the taxman will want 20-25% at the end of the year, then you will lose another 3-5% for each member of the family you pay health insurance for, your pension will cost another 10-14% etc In terms of deductions to get a decent level of “social protection” Switzerland is second only after Norway, UK is much less “taxed”.

The UN people are taxed at source i.e. the taxman gets their tax before the salary hits their bank account. So their salaries are “tax paid”, a mischievous female prime minister claimed this was “tax free” for political motives may years ago.

Erfolg,

You calibrate Switzerland very well, my compliments. To your list of companies you could add Logitech & Nestlé (you can buy Rowntrees’ sweets here now)

I think you will find the same quality approach on my club’s Website

http://sites.google.com/site/hanglfugchvu/

Do enjoy the photos, if not the language

Mark

[Richard Wood]

There are many highly innovative engineers & engineering companies

in the uk, despite engineering not being accorded the status it perhaps

should.

 

 

 

 

[Peter Miller]

Oh Dear, being accorded the same status as Orsone Wells  It just goes to prove that you should never base an opinion on limited information.

 

Mind you, flattery will get you a long way.

 

Yes, we come up with brilliant designs and then let them go to other countries that cash in on them.

[Tim Mackey]

Can we keep on topic please people

[kc]

Swissflyer, you are probably correct about Swiss employees'  taxes but if its not a tax haven why do leading racing drivers ( for example ) go to live in Switzerland. From J. Y Stewart to M. Schumacher etc etc.  For the mountain air alone? For the secrecy? Jackie S admits in his latest book why he went!    This is why we in Britain are so highly taxed at ordinary  levels.....the rich use the tax havens to avoid tax and at the same time influence the tax haven governments secrecy policies.   Maybe you didnt see recent BBC Panorama etc?

 Best not to mention Nestle to improve the reputation of Switzerland!  And of course its not ' Anglo Saxon tricks' .....you cannot make racialist comments here!

 

Anyway I am sure we all agree that engineers do not have the status in Britain that they deserve.  It's the 'bean counters' who wrecked British factories the expertise is still here ......check out the F1 racing factories locations.

 

What I cannot understand is why after 5 pages of comments there are hardly any comments from people who have electrified these free plans!   Censored by OS or SC or Enya to keep people buying glow engines perhaps?

 

[Erfolg]

KC

 

I suspect the principle reason no one has posted a conversion of the models on the list, is there size.

 

I converted the PM Cassutt as it was relatively small, My own being 36" span, I think Tommy's remained at 32"? span.

 

At these sizes 200-300 watt motors can be used, where are large range of motors at low/moderate cost are available.

 

The Lipo needs are moderate, any typical 3s, 2000-2500 size is viable, again freely available at low cost.

 

The servos, need only be budget 9g, without fear of overloading, even in a high speed dive etc.

 

As mentioned previously I have done bigger, than 36", but weight was carefully managed down to I think < 1.5kg all up weight.

 

I have considered converting some of these designs, but I have other projects, which have pushed them down the to do list..

 

As for those who choose to live else where to avoid tax, surely that is their right. If we want them to live here, perhaps we need to consider making it more attractive for them. Particularly when earned outside the UK.

 

I avoid tax every time I buy duty free, or choose to run a lower emmissions vehicle.

[Swissflyer]

Posted by kc on 02/11/2010 12:46:04:

What I cannot understand is why after 5 pages of comments there are hardly any comments from people who have electrified these free plans!   Censored by OS or SC or Enya to keep people buying glow engines perhaps?

 KC

For me Erfolg is right.

I have many times admired Peter’s models, thought about electrifying one, punched a few numbers & decided the heavy LiPo demand & consequent large cash outlay made other projects more desirable.

I think some of those downsides can be handled and those models made attractive if one is prepared to make a few practical compromises, I will post some ideas later

Mark

[kc]

Erfolg,

We need the rich to pay taxes to save the hardworking normal people from having to pay to subsidise the rich.  Why should you and I pay when the rich don't?  People who go to live in tax havens and dont pay full tax are scrounging off the rest of us.   Your argument that it is their right is ridiculous just see the example of that Green chap who pretends his wife earns the money  whilst in Monaco yet he lives off the rest of us whilst spending lots of his  time in Britain.  Despicable. 

 

Anyway to get back to the subject as the moderator asks,   thanks for the data on your Cassut, I just wish there was data on a lot more models.  Perhaps there will be when the data spreadsheet is filled.  But I suspect the main problem is people cannot accurately describe their motor by model number, often they know the make but not the precise model!   2 of of my fellow clubmembers are like that,  they tell me the make but cannot remember which one they were sold!