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72" Vulcan build

Can my next project be EDF

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andy watson11/08/2010 00:02:31
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I am getting into the closing stages of my stuka build, and giving thought to my next project.  I am drawn to the idea of a Vulcan bomber.  I am thinking about the one from South Herts models here.  This is designed for a 60 size pusher, but if anyone has read any of my blogs you will know an IC engine hanging off the back will annoy me.  Since a turbine or 2 is well out of my price range, I am wondering if it could be converted for EDF.  I will speak with the company to check for the practicalities of actually fitting them, but since I have never done anything electrical before (it's all been IC) I have no idea what kind of set up I will need, and hence no idea of potential costs.
 
If anyone could recommend a set up that would be capable of taking off in a Vulcan like manner, then I would really appreciate it.
 
Cheers
Stephen Grigg11/08/2010 10:11:28
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Wow Andy that would be a forumites dream thread please go for it.I think it would have to be electric,Someone at the club just bought hawk or something and it sounds awesome.these ducted fan thingies have come a long way.When you start the thread(please,I would be tempted to build one along with you.Mine of course would be a couple of posts behind so you could work it out for me.Hope it happens,Now we need Timbo to tells us the electric set up and cost.Good luck with your potential new project,your audience and public await you
Phil Cooke11/08/2010 10:34:21
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Model would certainly be suited for EDF if you can duct the air suitably around the wing joiners, theres plenty of room (depth of section) for the powertrain and the model can be built nice and light - I think ducting will be the biggest challenge!  PSSA member Matt Jones has built one from this plan for PSS and it flies superbly!!  He might be able to offer some advice on the build and weight reduction.
 
Certainly its a really good looking model when finished - the plans are taken from the original A V Roe wind tunnel drawings so the shape is spot on and it performs really well.
 
Heres Matts model in action off the Gt Orme.



 
 

Edited By Phil Cooke on 11/08/2010 10:37:54

David perry 111/08/2010 12:07:22
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Have a look at this  video.  Some interesting guide lines here.
 
Sounds a cracking idea though -  an email to Chris Golds might help too.
 
andy watson11/08/2010 16:46:33
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Cheers for that guys.
 
So I will need to duct air into the fan- presumeably in a similar manner as an IC engine needing cooling, but with the motor buried in the middle of the plane.  I guess that can be done.
 
The listed AUW for the build is 10-12lb based on the 60 IC option.  I don't know if EDF power will be heavier or lighter than an IC build, but what kind of power train do I need?  More importantly will I need to sell a kidney!?
David perry 111/08/2010 17:20:13
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Andy, the ducting is MUCH more critical with EDF than simply cooling for an IC motor, it really needs thinking through. The thinking through usually ends up with long shiny ducts. They are shiny because you coat them with money, ha ha.,
 
There are people better at EDF than me, but you'll need to think about (I would suggest) 200 watts per lb of this plane -  100w is a good sports model and the Vulcan needs to be able to whizz!  So you are after a total of about 2400 watts.
 
My rough calcs assume 4 0r 5S lipos and about 80 - 100 amp controllers.  Its a big beast.  If you used 5S thats 10 total, there's the first 200 - 400 quid and you havent bought the motors or ESCs.  And of course you'll need two complete flight packs!  Mind you, with the Vulcan wing you could probably use A123 or even, cough cough, nicads /  nimhs.
 
I'd phone some one like Puffin models and talk it through with them -  they'll sell the batteries and motors too.  Like I said, there are people on this forum too with waaayyy more expertise in electrics than me, but its a start.
 
Its exciting.
 
 
 
Tim Mackey11/08/2010 18:24:36
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Pretty ambitious project. I actually think that you could probably manage with less power than that, after all the Vulcan doesnt actually rocket along most of the time - in fact it often looks best when it just hangs there looking like its about to drop from the sky LOL.
Theres a huge wing area of course, so wing loading shouldn't be a problem - my guess is that you would get away with around 150 watt per pound, so that brought it down to a more manageable 1.5kW assuming 10lb AUW.
This is easily achievable with todays modern fans and motors.
A single 70mm minifan with the right motor and its glass filled 5 blade rotor can easily handle 700Watts+, so X four...... and you have 2800 Watts potential.
Selecting the right motor could get each fan down to around 400 watts and thats quite do-able on 4s batteries with a very reasonable 30A or so. This keeps the ESCs down in price as you could use 40A units.
Alternatively, would you consider "cheating" and using two larger 90mm fans each producing around 800+watts from say 6s battery. That way you only end up paying for two of everything instead of four. 
 

Edited By Tim Mackey - Administrator on 11/08/2010 18:59:29

Stephen Grigg11/08/2010 19:32:48
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If you wnet the  two fan way Tim what would be the cost approx of course
andy watson11/08/2010 20:30:54
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Cheers Timbo,
 
My guess would be "cheating" being the way to go, with 2 motors, rather than 4.  Then again things do seem to get exponentially more expensive as size/power increases so maybe there is no saving to be had there?
 
The link David sent is another plan build vulcan, about the same size.  Might have to get both sets of plans and see which might be easiest.
Tim Mackey11/08/2010 21:42:05
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Two Midifan ( 90 mm) units @ £45 each
Two 1800 Kv inrunners  @ £25 each ( best on 5s not 6s )
Or if your budget will go to these - could then use 4s batteries and mega are quality.
Two 60A ESCs  @ £28
 
Of course any alternatives abound, and the big fish do a range of complete EDF units these days also.
Stephen Grigg11/08/2010 22:38:03
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Thanks Timbo
andy watson12/08/2010 01:02:50
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Well that's do able price wise- although the £50+ batteries are what are making my eyes water!!
 
No doubt I will need a better charger and field battery as well!!
 
Just out of interest Timbo, are there any advantages to using 4s rather than 5s.  There seems to be no price difference, although the 4s are marginally lighter.
 
Good job it will probably be Christmas before I get onto it!
Tim Mackey12/08/2010 09:15:08
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Lower cell counts would be cheaper thats all.
Of course if you did go 5s or 6s then you would need a different motor (  other advantage is the current will be lower for the same given power)
 
Incidentally I would use one large capacity battery not two separate ones, perhaps made up from 2 decent sized packs in parallel like THESE
 This eliminates the slight possibility of one battery dropping low and acticvating that ESCs LVC before the other.

Edited By Tim Mackey - Administrator on 12/08/2010 09:32:31

Ed Darter24/08/2010 17:12:21
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ewww... watching this thread with interest, once my current project is off the board I am seriously considering the Graham Herschel Vulcan. I have the plan already ! I was going to go twin pusher route and build it from Depron as opposed to balse / ply. Keeps the weight down a bit, but not sure if this would be strong enough to cope with EDF.
 
Ed
andy watson24/08/2010 19:12:01
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Well the Stuka should be done in a few weeks, then I have a non scale aerobat to build- which shouldn't be too long.
 
Think my next build (which will probably be this vulcan) might start about Christmas.
 
I don't think it will be a particularly long one- at about 1/20 scale a lot of detail will be absent.
Tinpusher25/10/2010 19:53:24
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Andy,
 
there is some time left until Christmas, so maybe you are interested in this EDF Vulcan project from Germany:
The model has 65" wingspan and is built after the plan set from Mr. Cyril Carr that I received back in 1999 (!) in balsa and ply, covered with glass and epoxy. Powered by two Jepe 5s Fans with two 80 Amp ESCs, 5s2p Kokam 5000 Lipos. Weight as shown is 5kg an bungee launched. Just two flights so far, but from the first second on a joy to fly. Lots of power for nice climb-outs, scale cruise with 1/3 throttle. I will add some scale details in winter and paint her in a 1970's scheme next spring.
 
Frank
 



 
 
 
 
andy watson15/11/2010 10:20:53
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Sorry, I missed the last update to the thread,
 
I have bought the plans by Graham Dorschell.  Completely my fault, I thought they were for EDF, but they are twin pusher...... grrr
 
Anyway, having a good look at them- it's going to be a pain to convert to EDF, so I was kind of resigned to going pusher, but the plane above looks perfect!
 
Unfortunately I can't find a copy of the plans anywhere!!
 
Any ideas anyone?
Dizz18/11/2010 22:36:20
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Drawing I told you about has arrived - not the factory one though, he couldn't find it.  This one a scale drawing by J F Henderson.  Wing plan and outer cross sections different to the Warpain book pull-out plan so now I have to work out which one is correct,
Think I will start by checking against the Airfix kit.
 
Pete
andy watson19/11/2010 22:34:18
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It's an incredible hobby for finding people that are so generous with their time and expertise.
 
The Vulcan is taking a lot of interesting twists and turned- and I've not even started a build yet!
 
I started off by doing quite a bit of googling.  The problem is the idea of an EDF Vulcan seems incredibly popular- a lot of people have tread this path before me.  And very few have suceeded. In fact I have failed to find an EDF Vulcan in the 6'ish size despite it being so popular.  I read a few threads that mentioned Cyril Carrs plans that Frank mentioned above, but I couldn't find any for sale anywhere.  I found a few of his other designs, but not the Vulcan.  Unfortunately the threads (and Franks example above) all were pretty old, and I didn't know if Cyril was still active (or even alive!).  As if by magic the latest RCM&E arrived- and Cyril is plastered all over it and obviously very active!!  So I emailed David asking if he could put us in touch.  I got a message back with his phone number and we had a very long chat about the ins and outs of the project.  The bad news is his Vulcan was pusher too, which he later converted to EDF.  I'm guessing Frank did the same above-Frank- if you are still around can you let me know about your conversion?
 
He has, however, insprired me that converting the Dorschell plan is not as difficult as I thought, and minor imperfections in ducting are not as critical as some suggest.  In fact he seemed pretty confident- although he has never met me!! .  He did mention someone called Terry Mitchel that made a Vulcan with 4*50mm EDFs.  After I got off the phone I googled this hoping for a plan for sale, but failed.  I did manage to find an article about his plane on an RAF reunion site though, contacted the webmaster who again forwarded my contact details and I received an email from Terry today asking if I wanted to get in touch about the Vulcan.  Fingers crossed.
 
In parallel with this I was reading some EDF build blogs and I read one about an 1121 that mentioned the next build being a Vulcan.  That was Dizz above- who also seems to be taking a kind interest (he might regret that!), and is far more experienced in these EDF thingies.
 
So- the current situation is the most likely option will be Dorschells plans converted to EDF with 2*90mm fans; but if I am lucky I might get my hands on a set of plans designed foir 4*50mm fans from Terry.  Hopefully Dizz will be keeping an eye on things as well.
 
So no plans, no balsa, but I feel a step or 2 closer.  Not that I have done anything on the stuka except burn out a servo on the flaps. 
Ed Darter20/11/2010 21:29:29
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Well if you are successful converting the dorschell plan I will seriously consider doing the same as this is the plan I have ready to be started at some point.

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