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New 78" Vulcan for twin 90mm DF

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Greg Minden07/12/2019 20:00:41
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37 photos

Peter - you will be so glad you made it this way. Also helps immeasurably with routing the wiring. I believe i have about 35 ft of cabling in this model. img_20180623_140924.jpg

PeterF23/12/2019 11:15:29
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525 forum posts
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Progress has been a bit slow in terms of the amount of wood added to the plane. I have tackled the rudder and done this according to the plans and all has gone well. It is quite large, larger than the wings on some of my models so it has taken a bit of work.

The main reason is I have bought a basic 3D printer, my son has a model making business (not RC - wargame models) and he has a number of 3D printers, but he has been inundated with Christmas orders plus he had a special promotion on a new range of kits so he has not had time. Anyways, I have done a pair of pilots, taking the cue from Craig's build photos, pilots were 1/12th scale of Thingiverse and I believe the TN model is about 1/16th scale so printed them at 75%. These are the pilots with visors raised, hopefully more detail will show of their faces when painted. I have used the nose cone and tail cone supplied by Greg, spot on, thanks. I have not sanded the nose or tail cones until I got these. I have designed by own exhaust nozzles, I will post a little bit about these later.

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PeterF23/12/2019 11:22:10
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525 forum posts
724 photos

The exhaust nozzles on the plan are just some thin ply wrapped into a short tube. The advantage of these is that they have a minimal impact on the air stream flowing out of the thrust tubes. I have built the 3D model of the rear former and the air stream and original nozzles to show this.

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Greg has then gone on to make a 3D printed version of these.

However, I wanted ones with some conical shape on, but the trouble is that these will interfere with the air stream, so I have made the cone quite small and angled the two cones 3 degree inwards to reduce the impact on the air stream in the middle of the thrust tube. This does mean that the gap between the cones is reduced, but needs must. They have also been angled down 3 degree compared to the outlet former. The 3D model shows the limited impact on the air stream.

If anyone wants the file for the conical version pm me with your email address and I'll happily send it to you.

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Edited By PeterF on 23/12/2019 11:23:24

Greg Minden23/12/2019 18:54:51
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50 forum posts
37 photos

Looking good! Instead of painting my nozzles , i used a silver sharpie pen to color them. Gives a kind of meimg_20180517_182409.jpgtalic, steel finish.

PeterF05/01/2020 17:48:06
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525 forum posts
724 photos

I have completed the skeleton of the right hand wing, spars, ribs, leading edges, trailing edges, shear webs and wing tubes and this fits well with the fuselage. I mainly followed the photo pack. One thing is the photo pack does not exactly stipulate how to set the ribs up and I could not find a note on the plan either. One photo shows the trailing edges all set on the building board, so this is what I have done. I also put the front spar in place as a positioning device whist the ribs were fitted, then lifted it up and glued it in place later in the build. I also added the shear webs before lifting from the board in an attempt to keep everything more rigid once lifted from the board.

Ribs glued in place with the spars.dsc08610.jpg

Rear of the ribs level on the board.dsc08611.jpg

Front spar only used for location at this stage.dsc08612.jpg

Front spar lifted up once top spars, LEs and TEs have been glued in placedsc08620.jpg

Shear webs addeddsc08623.jpg

Wing removed from building board and trial fitted.dsc08628.jpg

PeterF12/01/2020 19:15:50
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525 forum posts
724 photos

Second wing skeleton completed and test fit. This is getting quite large now and will be too long to fit when the nose and tail cones are on. I need a considerably bigger workshop or I might have to take the doors of the wall cupboard.

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Greg Minden12/01/2020 23:04:00
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50 forum posts
37 photos

looking good!

PeterF05/02/2020 16:00:51
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525 forum posts
724 photos

It has been a while since I posted but I have been working away and making good progress.

The topic of this post is how I have designed the wing retention on my model as the plans are silent on this issue. Ideally this should be decided upon before the wings are sheeted, otherwise you will need to cut patches out of the skin.

I have glued ply plates onto the wing tubes either side of the wing joint and reinforced these with triangular stock, all glued on with lashings of epoxy. Threaded inserts had already been glued into the ply plate using before gluing them to the wing tubes. The outside of the inserts is knurled to give a good grip when glued in. Slots are then cut into the root ribs and a short 3mm aluminium bar with holes in the appropriate locations is then screwed to the inserts in the ply plates using cap head screws through small holes in the upper sheeting. By appropriate use of shims, the head of the bolts is relatively flush with the wing surface.

The main aluminium wing tube (the rear one) needs some form of stopper to prevent it migrating in and pressing against the exhaust duct from the fan as this is flexible and will deform allowing the tube to move and the fan performance to be reduced. During the wing attachment, a small piece of sheeting needs removing so you can glue the wing tube to short rib WS1. I took advantage of this and glued 2 sheets of ply between WS1 and the exhaust duct, the first sheet of ply was 2.4mm and had a hole in to match the wing tube so that the wing tube could pass through WS1 by a small amount. The second sheet of ply was solid and this stops the wing tube moving inwards towards the exhaust duct.

Pictures may explain things better.

Ply plates glued to the wing tube shown from above before sheetingdsc08717.jpg

Ply plates shown from below with triangular reinforcement from below after sheeting the top surfacedsc08689.jpg

Wing section removed showing aluminium tubes and aluminium strip to lock the wing in placedsc08706.jpg

Upper sheeting showing the two cap head machine screwsdsc08702.jpg

Two layers of ply between short rib WS1 and the exhaust duct with a hole in the first additional ply layerdsc08710.jpg

PeterF05/02/2020 16:17:39
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525 forum posts
724 photos

The first wing has been completed and this followed the photographic instruction sheet and the plans. Sheet the upper surface, add strengthening blocks at some corners, add the elevator and elevon hinge blocks, add the servo rails, sheet the lower surface and cut off the wing, which is shown in the post above. The only area I have deviated is to mount the servos into plastic covers because the plan calls for the servo tops and horns to be exposed. I have 3D printed some servo covers and I have gone back and reworked the rudder servo to match. The second wing is coming along now that the first one is completed.

Wing skeleton being glued into place on the fuselage.dsc08676.jpg

Top surface sheeted.dsc08680.jpg

Servo rails / hatch for the inner elevator.dsc08688.jpg

Servo in 3D printed cover.dsc08693.jpg

Servo for the outer elevon mounted in position before sheeting the lower surface.dsc08696.jpg

Bottom surface sheeted.dsc08698.jpg

Rudder servo reworked so it is not exposed.dsc08691.jpg

Craig Carr05/02/2020 17:00:04
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706 forum posts
504 photos

hello Peter

all looking spot on I did the same but used some commercial slec ones

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Greg Minden05/02/2020 19:26:26
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50 forum posts
37 photos

Good work Peter. BTW , have you measured the wingspan yet on your "78" Vulcan?

PeterF05/02/2020 20:19:14
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525 forum posts
724 photos

Yes, it is about 78" at the moment, when I put the wing tips on it will be about 83". Not sure why it is called 78".

PeterF10/02/2020 17:08:22
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525 forum posts
724 photos

The second wing has now been completed to the same stage, sheeted both surfaces, servo mounting rails installed, wing tubes cut and checked. I have added another photo of the wing retention system before sheeting with the aluminium plate bolted into place on both sides of the wing joint. As noted previously, I have followed the photo instructions. The oddest job was gluing the wing frames to the fuselage and sheeting over everything, then cutting off the wing panels afterwards, first time I have ever done anything like this. From the photo below, the wing joint is between the second and third ribs, which are spaced a hacksaw blades width apart with some thin balsa sheet, ready for cutting after sheeting is complete.

Ready to add the leading edges, wing tips and the control surfaces.

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Greg Minden10/02/2020 20:54:13
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50 forum posts
37 photos

that's how to do it!

PeterF23/02/2020 19:54:49
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525 forum posts
724 photos

Leading edges, wing tips, inner elevators and outer elevons now all completed. The only bit that has given me some pause for thought was how to build the outer elevons with the reflex built into the outer half of these, none of the surfaces were flat to build them on the board in the normal way. I have tried to sand the trailing edge of th wing tip blocks to follow the reflex on the outer part of the elevons.

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Edited By PeterF on 23/02/2020 19:55:30

PeterF28/03/2020 20:44:16
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525 forum posts
724 photos

I have added the inner sheeting in the inlet ducts. I have made this full lenth back to the former with the fan inlet to give a smoother flow area for the air going to the fans. The corner infills have also been added. I have fixed the rudder in position and added the spine along the top of the fuselage.

That about finishes the majority of the build. Now to start sanding and filling in preparation for glassing, parcel arriving Monday from East Coast Fibreglass Supplies. That will keep me occupied for the next 2 weeks of lockdown (or more).

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Greg Minden28/03/2020 21:38:41
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50 forum posts
37 photos

img_20181015_161433 - copy.jpgLooking good. I became worried that the flat bulkhead next to the fan intake would reduce efficiency and power so decided to fair in the inlets to the fan. Seemed like a good idea and my thrust measurements would agreeimg_20181015_161525 - copy.jpg

PeterF28/03/2020 23:30:04
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525 forum posts
724 photos
Posted by Greg Minden on 28/03/2020 21:38:41:

Looking good. I became worried that the flat bulkhead next to the fan intake would reduce efficiency and power so decided to fair in the inlets to the fan. Seemed like a good idea and my thrust measurements would agree

My view on this is that with a full lip on the fan inlet, it should not matter as this will feed the air smoothly into the fan and the inlet area is larger than the FSA so that air flow will only need to change direction and accelerate at the fan inlet. The proof will however come some time in the future as I will not be cutting the access hatches until I have glassed the fuselage.

Craig Carr29/03/2020 06:23:04
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706 forum posts
504 photos

Hi peter,

your ducts look great, very neat.

How did you make them, I found pre-making a balsa tube as shown on the plan then inserting nigh on impossible and gave up after a couple of attempts. In the end the only way I could do it was to carefully build the duct”in situ”

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PeterF29/03/2020 10:18:34
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525 forum posts
724 photos

Craig,

I did not take any in build pics of the ducts. I made up a single sheet of balsa larger than required but did not glue it into a tube. I soaked it and then formed a tube smaller than the intake with a loose overlap and inserted into the hole. Once in the hole I expanded it to fit, marked off the diagonal front of the intake and the point where the overlap came to. I then removed the sheet, cut back to the diagonal lines leaving some spare and cut back some the spare overlap, but not all of it. I then refitted the sheet to recheck the overlap position, removed it and made the final cut. I then glued it into a tube and inserted it for the final time, but to get it in it needed to be soaked again and one of the flat faces bent inwards to make the overall size smaller than the hole. Very fiddly.

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