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New 78" Vulcan for twin 90mm DF

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Craig Carr02/12/2018 23:18:57
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674 forum posts
430 photos

Excellent job Greg,

Well done. Looks brilliant.

I’ll email you tomorrow re the retracts.

Next step.... the maiden yes

Craig

Greg Minden29/12/2018 20:30:46
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32 forum posts
34 photos

rtf2.jpgAll dressed up now and ready for maiden when weather is betterrtf5.jpg

Greg Minden20/04/2019 00:27:11
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32 forum posts
34 photos

mar 26-6.jpgmar 26-5.jpgmar 26-10.jpgSo a few nice pics from flight #3 a few weeks agomar 26-1.jpg

Timo Starkloff20/04/2019 09:03:29
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348 forum posts
777 photos

Magnificent

PeterF16/10/2019 20:36:18
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437 forum posts
598 photos

Now that it is building season I was looking around for this years build. I have a full set of gear (Fans, motors, ESCs, radio kit, servos, retracts) for a twin 90mm EDF from a former model and I was undecided between this and a couple of other options. Seeing the results of Greg's build has prompted me to choose the 78" Tony Njhuis Vulcan. I saw these flying from time to time as a child. My wife grew up in a small village north of Lincoln and needless to say seeing Vulcans in flight was a day to day occurrence for her. A huge box turned up today and I only ordered it over the weekend, soon had the contents spread out on my workbench.

dsc08317.jpg

As other people have commented, it is called a 78" model, but the wingspan on the plan is actually 83" (211cm) with the fuselage being about 75" (190cm) long.

I have one question for people who have built this, I can not find any use for the large vac formed part circled in red. I assume it is an optional cover for the end of the jet pipes, but the plans and photo build instructions make no mention of this.

dsc08319.jpg

Not sure if I will keep adding to this thread or create my own build log for this.

Greg Minden16/10/2019 22:06:52
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32 forum posts
34 photos

Peter - i don't believe i used them. I think they could be used to form the bottom aft end of the thrust tubes. I just carried the sheeting all the way back. See my pic on page 4

Greg

Craig Carr17/10/2019 16:26:23
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674 forum posts
430 photos

Hello peter

youve been sent that part in error. Same thing happened to me, it relates to the smaller 49 inch Vulcan and is the underneath cover for the thrust tubes etc

so your safe to forget about it

you may see it fitted here in this picture of mine

craig

img_1930.jpg

PeterF17/10/2019 17:47:08
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437 forum posts
598 photos

Craig

Thanks for the info and photo of the smaller model showing where they belong. I have found the album containing your build pics of the 78" version, they will make a handy resource, your build is coming along very nicely. I wondered why you had so many weights on the ribs when building the fuselage. Now I have released mine from the sheets of lite ply I know, they have all taken on subtle curves.

Craig Carr17/10/2019 17:52:54
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674 forum posts
430 photos

Yes the ribs in my kit were shocking once released..... they were all over the place.

fair play to Slec they changed mine free of charge because they were so bad. I also asked if they would do the 2 wing ribs which are the face ribs on the fuz and wing out of birch rather than light ply. They were much better

Scott Edwards 217/10/2019 19:21:41
180 forum posts
96 photos

 

The longer ribs that came with mine were like a DNA helix ☹️ I soaked them and force dried them flat which helped. If I were to do another one I would ask for a quote to cut them out of 5mm balsa perhaps.

 

Edited By Scott Edwards 2 on 17/10/2019 19:22:08

Greg Minden17/10/2019 20:08:26
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32 forum posts
34 photos

# Me too!

I ended up having to recut most of my ply ribs and those for the nose and tail sections myself - grrrr.

BTW Craig - have you finished your painting? Test flight?

I still just have 4 flights on mine. Just coming out of the blazing summer you know.

Greg

Craig Carr17/10/2019 20:57:42
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674 forum posts
430 photos
Posted by Greg Minden on 17/10/2019 20:08:26:

# Me too!

I ended up having to recut most of my ply ribs and those for the nose and tail sections myself - grrrr.

BTW Craig - have you finished your painting? Test flight?

nope embarrassed Painting is all it needs now

43d8583a-2179-47dd-8ac1-d8a89e3767ce.jpeg

PeterF26/10/2019 17:33:37
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437 forum posts
598 photos

Luckily, whilst my light ply ribs are a little warped they are not too bad so I have started the build. I will add to this thread as a sort of build log, but I am not going to make it super detailed. Tony provides a photo based instruction document which covers most of the step by step stages.

One thing I have learnt after building a kit with CNC routed parts is the router can not cut sharp internal corners there is always a small radius of 1mm or so from router bit. Therefore, I always go over all the internal corners on jigging tabs / spar slots / half joints with needle files to remove the radius, otherwise the tabs / spars / half joints do not always press home fully.

The central spine of the fuselage has gone together easily, with ribs 1 & 2. To keep them all straight and spaced during this process because of the slight warp, I have added some temporary 6mm spars from scrap along with pins, packing pieces under W2 because that sits above the building board level and set squares etc. Luckily no need for heavy weights to keep everything in place.

dsc08354.jpg

dsc08358.jpg

Craig Carr27/10/2019 07:57:35
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674 forum posts
430 photos

Hello peter,

All looking spot on. Yep I did the same with temporary pieces to help keep parts straight and cut them out again once the structure was rigid.

it was a nightmare keeping it all trueangry 2..... must have checked them a hundred times...

Greg Minden27/10/2019 17:52:05
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32 forum posts
34 photos

What he said! Nightmare. Almost all the cnc ply pieces. I had to remake.

Martin McIntosh27/10/2019 19:40:31
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2947 forum posts
1083 photos

Sounds just like the SLEC cut cnc pack for a 72" Spit. I built. Whatever the ribs were made from it was not what I would call lite ply.

PeterF30/10/2019 17:37:50
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437 forum posts
598 photos

Posted by Martin McIntosh on 27/10/2019 19:40:31:

Sounds just like the SLEC cut cnc pack for a 72" Spit. I built. Whatever the ribs were made from it was not what I would call lite ply.

Martin,

You are right, the outer sheet of the lite ply is something with a very porous open grain structure, it really soaks up the glue leaving little hanging around the joints. Whenever I have bought a kit with lite ply before, the outer layers of the ply have been similar to normal ply, with a light softer wood in the core. Quite odd, but onward with the build.

I have got most of the ribs and spars together to make the frame for the fuselage section including the fan mounts. Once this lost is together it creates a relatively rigid box structure. Whilst gluing all the spars and formers into the ribs, I have used some carbon fibre rod to keep the ribs straight.

A couple of things on the plan if you are reading this before building one of your own. The plywood spars FS1 need to be notched at W2 as W1, W2 and W3 are not uniformly sloped at this location, it is not noted on the plan. Secondly, the rear tabs on the ribs WS1 were a bit long and they fouled FS2 / FS2A, sand them down and it all goes together. The final thing, the front 9mm x 9mm spars should be hard balsa, the plan does not state so I started building them in obechi and then found that there was not enough obechi in the wood pack to complete them, so off the the LMS to buy 2 more strips to complete the spars and replace the wood I had inadvertently used. Oh, well, check next time the plan is not specific on a point before applying the saw and glue.

Fuselage section ready for sheetingdsc08382.jpg

Carbon fibre tube to keep the central spine straightdsc08379.jpg

Notch on FS1dsc08361.jpg

Rear tab of WS1dsc08364.jpg

Greg Minden30/10/2019 18:20:57
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32 forum posts
34 photos

looking good Peter. Here's where i posted my build thread

https://www.rcgroups.com/forums/showthread.php?3024529-Vulcan

PeterF02/11/2019 23:44:47
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437 forum posts
598 photos

Greg, thanks and checked it out, very useful as more detail than on here. I like the idea of the top access hatches, I'll have to think about that. I have had one plane with the battery access underneath and it was a real pain and in this case with 4 XT90 connectors to make each time!!!!.

I have completed sheeting the top of the fuselage section to the fan mounts and built up the nose section. This is relatively straightforward as it uses interlocking pieces, but being light ply, you need to make sure everything is straight before gluing. Not quite ready to glue the nose onto the fuselage yet, but it was a quick win in terms of progress.

Top sheeting completed to fansdsc08428.jpg

Top sheeting completed to fansdsc08434.jpg

Nose section under construction and checking for straightnessdsc08376.jpg

Test attachment of nosedsc08435.jpg

PeterF04/11/2019 17:20:23
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437 forum posts
598 photos

Last few days have been spent wrangling the fans and thrust tubes into place but they are now in there and work OK. Thrust tubes from Mylar from a craft shop used for stencils and Gorilla tape. I made the thrust tubes parallel because the change in shape to an obround at the outlet will cut down the cross sectional area close to the FSA of the fan. For a plane like the Vulcan where speed is not of the essence there is no point in reducing the thrust tube outlet to smaller than the FSA to increase the efflux velocity. In fact the obround holes in the outlet former were larger than the thrust tube, so I put some infill strips of balsa to close the gaps up and stop the thrust tube deforming at high throttle.

Fans and thrust tubes installeddsc08467.jpg

Fans and thrust tubes installeddsc08456.jpg

Outlet former larger than thrust tubedsc08449.jpg

Outlet former with balsa infill to match thrust tubedsc08452.jpg

Balsa sheet to control the obround shape of the thrust tube at the outletdsc08453.jpg

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