Avro Vulcan build

So my plans to crack on with the Firefly have gone to pot. I received a laser cut wood pack and plan of the Avro Vulcan, supplied by Sarik Hobbies, as a Christmas pressie. This is the Graham Dorschell design / plan, 68" wing span, with two pusher props. First impressions of the wood pack is positive. The wood is of good quality and straight. Some formers require joining up as they are so long. The plans are on 2 sheets, fuselage and wing. ABS mouldings are good quality. These include nose and tail moulding, clear canopy and a few other bits.



The fuselage extends out to part of the wing. So the outer wing panels are removable which makes it easy for storage and transport.

There are a few anomalies in the design that do not follow the full size. The main undercarriage is in the wrong place, to close to the centre line, in front of the outer engine. Full size has it outside the outer engine. Elevator is the same size as the aileron. On the full size the elevator is much larger than the aileron. That's what I've spotted so far. I am not going to modify it to take EDF's but will leave it with the pusher props making is semi scale. Even so the undercarriage needs to be in the right place and the elevator needs to be the right size. I will change these which will require some rework of the design.

So started the build today. Joined the two main formers. These come in two parts due to their size and require joining. The wing tubes are 10mm aluminium tubing. I will use these as the guides to lay out the wing and ensure I don't build in any twists. These tubes are boxed in with balsa. In some formers there is a square cutout 25mm square to allow the tube box to pass through. Some formers have round holes laser cut in the formers for the tubes.However, the holes are 12.5mm and the ally tube is 10mm. Why??? First design error. So for me to build accurately using the tubes as the guide I had to 3D print some round and square adaptors.





These were then fitted to the formers, slid over the tubes and everything lined up. Well nearly. The outer rib is too far forward. So I recut the holes to get the rib to line up properly. Error 2. As i am going to move the undercarriage to its correct location this meant that some of the wing ribs would be moved from the wing and built onto the fuselage section.





So that's progress for the first day. So far the design leaves a lot to be desired, no tabs to align formers making the build simpler and more accurate. Those that are provided are in the wrong place. I'll crack on tomorrow and see what else crops up.

Ralph
I would suggest that using printed guides in plywood for the ally tubes is no bad thing. I am pretty certain the wear/load characteristics of printed plastics is rather better than ply and they can also be made to give exactly the desired degree of 'fit'.

Now that looks interesting ! look forward to seeing it progress. I'm guessing the the 4 batteries required will two 2s in series for each motor?
The prototype motors seem like a good choice, as they can run smaller props than the T 4240 540 watt , giving more ground clearence. They are a lot cheaper too, but recommend 60A esc's . Still you are a way off from that choice yet.

I wonder if it could be adapted to use one turbine.

Sarik - I recall reading somewhere that someone else had a Sarik kit, and gave up with it, because the provided parts were a different size to those shown on the plan. When he wrote in to query it, he was met by a stony silence.

It could be adapted to take a single turbine but in my opinion there are better designs out there for that. Try Tony Nijhuis designs. He already has a design for that.

Boxed in the wing tubes in the main fuselage. Rather than just boxes I made the sides the same height as the ribs to transfer the loads across the ribs into the skin.



I've started on the outer wing panels. Managed to build a right and a left wing first time!! [badass]



Had a play to see the size of it.



I added a false leading edge to support the wing ribs and provide alignment and ensure I didn't build in any twist. Well if I did it would be the same on both wings!! :lol: :lol:

Very nice.
On the face of it your wing tube boxes look stronger than the spars.

I agree Q a little over engineered but at least i'll have a large piece from the wreckage if it crashes!! :lol: :lol: :lol:

Did a bit more today. Worked on the intakes. These are quite critical as they are very prominent on the full size, so getting them right is a priority. The plan shows a top and bottom 5mm balsa plate. So I stuck to the design but made some minor changes to the leading edge. On the full size the lower intake lip is slightly aft of the top intake lip. Also the shape is tapered to follow the leading edge. Spent a lot of time getting this right.



Then had to do the other side and get them to match.



Quite pleased with the outcome. Then added the nose formers and stringers. This is shown on the plan as the location for the battery. A quick calculation of the moments shows that the battery needs to go slightly further to the rear. So plan is to make the nose cone removable so I can either put the battery as per the plan or insert it from below behind the front nose leg through a hatch. If the battery goes where the plan shows I'm concerned that the weight will crack the nose off in a heavy landing. So beefed up the intersection between the fuselage and nose by changing a couple of the stringers with spruce rather than balsa. I may also add a couple of shear plates from balsa as an added measure.

I really admire your attention to detail ! Question; In the photo of the spec's the requirement was for four batteries, I take it you are going a different route ?

Hi Crash. Yes, I shall be going for either a single or two batteries.

There are benefits to both. A single battery is easier to manage, the fuselage is big enough to take a very large battery. Downside, if the battery fails then all thrust is lost. I wouldn't lose control as the avionics will be powered by a separate BEC from a separate battery.

Two batteries give redundancy for the BEC as I would power the avionics BEC from both batteries (dual supply), no separate BEC battery (less weight), downside if I lose one battery then I have asymmetric thrust which is not good on a delta (asymmetric thrust would be quite small due to the short distance between the centre line of each motor and also the very large fin fitted with a rudder), two batteries to manage and secure.

A few things to think about. Personally I prefer the two battery set up. I use similar on my competition F3A pattern plane although they are paralleled up, but management is now a routine task for me.

The time spend on this build over the last two days has been spent trimming the structure and adding strengthening parts. So not a lot to show for about 8 hours work. Anyway the frame is pretty well complete, just got some fettling of the airframe for motor and servo leads then onto the sheeting. The nose is removable as planned.

Blimey!! you don't muck about Ralph do you? nice build, any thoughts on a colour scheme?

Nice work, but I can see a major flaw - you have no holes in the ribs for the servo leads! :evil:

Slightly off topic, but on the topic of Sarik, my understanding is that Sarik rose from the ashes of Traplet, with much of the upper hierarchy still in place. Problems with the Hawker Fury mass build were glossed over on the other side but my source told me there was an unwillingness to make waves because of the advertising revenue!

This is just one of the problems, the spinner, or the cowl, or both is/are not fit for purpose! I haven't started yet, I'm not sure I ever will.