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Park size Avro Vulcan pusher prop

Old 02-05-2019, 11:49 AM
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solentlife
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Default Park size Avro Vulcan pusher prop

OK ... everyone knows the Avro Vulcan ... its Howl being legendary. Unlike many other cold war machines - it actually did see combat in the famous bombing run of Stanley Runway in the Falklands Conflict. An amazing bit of logistic to get one bomb on target !


Well worth the time to watch ....

For a long time I have looked over various plans and ideas for this iconic machine to build. but that wing and intakes have stumped me till now. I owe RCPowers site really for the ideas and solution to this having now built their Mosquito.

Print of plans ... and beg stl files for the nose area ... check I have enough Depron left .... and think about how to power it.

Various have used EDF's .... but to keep exhausts scale size - means huge model and lightweight building techniques I do not possess. That sort of exercise I leave to the professionals like Quorneng !!

For me with my overweight style - it has to be pusher prop ... single or twin ? At this stage I think twin ... but I'm open to change of mind.


Having now printed out a plan from my archive based on ~36" ... I get following stats :

Fuz length 750mm
Wingspan 860mm
Max chord 440mm
Tip chord 100mm inside of curved
Max fuz depth 70mm
Max fuz width 70mm
Fin height 120mm

This puts a basic outline well within a single Depron sheet of 1200 x 800mm. It will need a second sheet to provide the top sheet to the wing.... and this will be slightly greater chord to allow for the form curvature. The second sheet can provide both spars + an additional filler spar where ailerons are cut out. The spare of both sheets if carefully cut can provide all of the bulkheads etc.
The wing spar being at max 65mm less sheeting of 2x 6mm means I can get away with a 50mm spar height and 12mm thick with CF rod embedded.

Forgive me if I use this as a "jotting board" of thoughts.

The fuselage and wing can be allowed as I did with Concorde and TU144 be combined for the bottom shape and form. It does mean though - the semi-symmetrical real form will not be copied and wing will be flat bottomed. The nose and tail parts cut longer and without taper so when sides are brought in - the ends can be curved up and then cut back to match. As with the Mossie and Lanc - the nose and tail can be squared to make construction more easy. (My Concorde and TU144 once in the air look the part).

That is sure one BIG wing for what is a small scale model ! The factors dictating size - is to have model as one piece .... and to be powered by smallish pusher props where jet exhausts are.

I may if I get really carried away see about forming a 3d nose for it ...

Pitch in anyone if any ideas / thoughts ...
Attached Files
File Type: pdf
Vulcan36inch full size.pdf (1.52 MB, 27 views)
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Old 02-05-2019, 02:52 PM
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Old 02-05-2019, 04:18 PM
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3D nose and tail cones printed ...

Print-Rite after cropping to fit height..



During print ..



Completed nose cone to fit plan ..

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Old 02-05-2019, 05:09 PM
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Old 02-05-2019, 05:29 PM
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Work in progress, in wood, 78", 90mm edf's.
tonynijhuisdesigns.co.uk/pdf/78inVulcanBuildphotos.pdf

Build thread
www.modelbouwforum.nl/threads/avro-vulcan.263627
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Old 02-05-2019, 06:42 PM
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I have the Tony N plans ... and they produce excellent models.

I'm after a simpler quicker build that will be near scale looking in the air.

Cheers
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Old 02-05-2019, 07:03 PM
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solentlife
Very nice! A twin pusher, motor in outer exhaust pipe, should end up almost invisible.
Are you sure you will actually need such a big carbon spar?
The Vulcan wing is pretty thick where it needs to be so I have a sneaking suspicion that with the skin suitably supported by internal Depron structures (2" max unsupported distance) you won't actually need a spar at all!

Remember to look impressive, as did the original, a Vulcan should fly slowly - ridiculously slowly. The air frame was strictly speed limited at low altitude and it only reached full speed at a height nobody on the ground ever saw it!
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Old 02-05-2019, 07:59 PM
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Hi Q ...

Yes the similar thought ran through my mind. That's one hell of a wing and the depth does give rise to quite a meaty foam spar. But I am not presently expecting to create ribs or structure under the skin. But am considering a twin spar layout due to the sheer wing size and area.
That wing is one large mother !! Once I get it cut and see what I'm playing with ... I reckon my ideas will change !!

Speed ... yes - and I think it surprises many people that she in fact was sub-sonic as well even flat out at altitude.
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Old 02-06-2019, 05:47 PM
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OK .... before I start putting up actual build photos - I am one of those that can actually build from a minds eye picture. While I'm sketching - I can input / remove bits to suit without actually having a full final plan.

First I had to sketch out a second wing panel so I could cut the whole in one go ... 3mm used for a template. tap out from the plan ... then lay 3mm template against that and create the mirror + original whole.



Cut out the basic shape as a flat plate ..



The cut out the side on view of fuselage .... draw centre lines on both wing and fuselage sheets ... mark of tabs for joining tigether to create the basic model ..



Now I have the two pieces laid out and BEFORE I cut fuselage in half to create the longitudinal spine ... will consider the wing and whether it has a spar top and bottom to create that iconic depth by sheeting. I could make life easier by accepting a fuselage below the wing for entire chord and it stay flat bottomed along centre line of fuselage.

Thoughts guys ...
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Old 02-06-2019, 06:38 PM
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OK ... I'm gluing in the spine top and bottom ... will then create the foam spars and slot the fuselage spines to have spars full span ...

Once that's in - then I can create the shell formers to make the fuselage and wing depth ... with the taper out.
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Old 02-06-2019, 07:11 PM
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As Quorneng mentioned to me ... with that wing and it not being a massive build ... could possibly not need CF spars ...

With doubled 6mm spars top and bottom .. and sub spars because of the wings chord ... could be foam alone.

Its already looking like a Vulcan !



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Old 02-06-2019, 07:18 PM
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Boy do I need my Workshop fininshed !

Needs electrics and something covering floor and walls ... + furniture.

I must check out eBay for Bar Optics ... always fancied having the wall mounted optics for the whiskey / vodka bottles etc.
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Old 02-08-2019, 12:50 PM
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As many here already know - I tend to be a 'wing and a prayer' cut as I go builder. Having sketched the initial plan - its been a brain-job to figure out how to contour that wing to fuselage while keeping those intakes and exhausts shapes.

Bit of artistic licence called for and as Quorneng said - who could ever argue with THE master anyway !- the wing with spars / structure becomes remarkably strong. I will need no CF at all.

I left last post with the X form wing and fuselage spine. I finally came up with an idea and started with the engine intakes ...





Idea to remove the piece of wing crossing the intakes later after skinning.

Next was to see about those iconic exhausts ...





Again remove wing bits later ... and I hope to 3D print tubes to glue on for exhausts ...

Then had to think how to grade that wing sheeting with spars and formers. Here's the spars in and similar underneath of course ...



The wing already now is stiff and I reckon once the top and bottom 3mm sheeting is added - will be more than strong.

Process now in my mind is to actually near complete the build so I get the overall shape - THEN make the cut-outs for gear. Of course any wiring needed for servos / motor will be pre-installed over length before closing up. Possibly not sheeting top of model till sorted. Its all 'suck and see' at this stage.

But it looks like a Vulcan already !!

The central mounted motor ... yes I decided single motor in the end will be the usual 2200kv jobbie with 6x5 prop on a 3S ... I will mount a touch higher than the real tail - to try and give me rotation angle on her wheels before prop clips the deck. Its possible that I may not fit the retracts ... but at present they are on the cards to be fitted. I will need to buy a steerable nose wheel set to match my fixed mains.
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Old 02-09-2019, 10:17 AM
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Found some ideal thrust tube exits that scaled down are perfect ...



Now to match in with the blisters running along underside of wing / fuselage sheeting once sheeted.
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Old 02-09-2019, 11:55 AM
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Having now measured up the 2826 2200kv motor / adaptor and prop ... it clears the nozzles perfectly with leaving the cone of the adaptor about right for the tail cone.

I am now printing up the X foam motor mount that is perfect for the 2826 ... https://www.thingiverse.com/thing:2466778

Still considering how to get the wing sheet to conform to allowing the fuselage / jet engine shapes to be included..... it initially looks a simple delta - but in fact it is not. With the intakes and the rear exhausts - this creates a form that needs careful design to accommodate. The more I think about that exhaust part - the more I think I will have to accept squaring it off and accepting the non scale shape.

Maybe the Blended Malt I am sipping will help the thought processes !! Certainly eases the bones in the cold we have !
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Old 02-12-2019, 11:28 AM
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Engine blisters in place and sheeting in progress.





Top sheeting will wait until I have sorted out internal gear.

I ma having trouble getting a matching nosewheel retract for my mini 28 x 25 mains ... so it looks like I will have to use a heavier nose retract. I have 3D mount for the heavier ... so that will be printed of and sorted to fit. That is of course once allowance for steering servo made.
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Old 02-12-2019, 11:41 AM
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Nice looking project Nigel.
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Old 02-12-2019, 12:35 PM
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Tks Don .... was starting to wonder if anyone watching !!

It really is a 'scratch and see' ... initially you think its just a delta wing and all is easy. But in fact with the fuselage blended in and the engine nozzles etc. - it makes the centre section along with the intakes and rear hard.
Originally my idea was to use 2x 6mm to make the wing but as I looked at the drawings - it became obvious that a 6mm base with 3mm sheeting either side would be needed.

This design is also a test bed for the 'new glue' I found. The usual spray glue used by many to laminate foam ... stick plans to sheet etc. is VERY expensive and hard to get over here .. 3M 77 or whatever it is ... so I searched for an alternative. Bison Foam Glue .. and so far its working a treat. Its laminating my elevons so far ... "Bison Colla Spray"
Once I get used to spray and hold .. I may start using it for smaller jobs instead of areas ...
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Old 02-12-2019, 11:59 PM
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solentlife
Indeed watching with interest.
Unfortunately there is no "thanks" button as a way of showing I have visited each post.
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Old 02-13-2019, 08:03 AM
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Latest is actually figuring out whether to really go for wheels ... the underhang of prop and angle of rotation means LONG G G G G legs ! If retracts - that means big holes !!

But there's no hand holds for hand-launch ...

I have Stinger fixed gear spare that I can fashion longer legs for ... its removable as well ... or a dolly ?
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Old 02-13-2019, 10:17 AM
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Another way to get her well on way of course is the good old bungee !! The stinger nose assembly leaves a pin below the underside that can take a bent rod as hook ..... or just a collet to stop bungee line falling off before launch.
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Old 02-13-2019, 10:51 AM
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Crossing ,my mind that if I build again .... maybe 4x 30mm EDF's ?
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Old 02-13-2019, 11:34 AM
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The EDF option would be interesting. I like the simplicity of your pusher design though.
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Old 02-13-2019, 11:58 AM
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I have just started to weigh and draw up stats for my build.

Airframe 70% done incl 2826 2200kv motor / prop = 235gr ... estimate ~300gr fully sheeted
Additions (wheels, legs, 3D nose, servos, Rx) ~170gr
3S LiPo from 160 - 190gr depending on which needed to balance out.

That makes her ~ 660gr all up ... which given the wing area is not so bad ...

Span 850mm (I did intend 1000mm but in the end made all fit the sheet)
Root chord 430mm incl intake
Wing area ~27sq dm
LOA incl prop boss 770mm
CoG is calculated at 410mm from nose (170mm from wing intake to fuselage joint)

eCalc gives it excellent figures ... taking a 2200 3S LiPo ... 6x4 APC E prop

C rating 9C (means no high power LiPo needed)
Mixed flight time 11mins
Max E Power out 203W
Thrust to weight 1.3 : 1
Pitch speed 118kph
Vertical climb 31kph
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Old 02-13-2019, 12:08 PM
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Originally Posted by Don Sims View Post
The EDF option would be interesting. I like the simplicity of your pusher design though.
Agreed ... saves all that ducting !

But leaves me with the ground clearance on rotation ... eClac shows I could go down to a 5x5 prop ... but blade will stall until it gets some speed up ...

If I drop back to a 4.5 x 4.5 prop and shove a 4S in her ... speed goes up ... but she has blade stall that needs to be noted.
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