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Trident airliner scratch build

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Trident airliner scratch build

Old 02-23-2021, 01:37 PM
  #26  
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Cool project. Look forward to seeing this one fly Alistair.
Old 02-24-2021, 07:57 AM
  #27  
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Now the tricky bit.
I have never done a planked fuselage before. But how else can I make the rear fuselage? And keep it accurate.
So I assembled the parts shown earlier, with a few others, over the side view of the fuselage with integral fin and engine intake.



The bones of the right hand half of the rear fuselage.

I started at the 1/4" x 1/8" balsa longeron and added tapered strips of 1/16" balsa, adding two at a time (one above and one below) using aliphatic glue as it's supposed to sand easier than cyano.
I held all the parts in place while the glue dried with many pins and lots of little clamps.
Trouble is, it takes a while to set. So it took a while.
After some trial and error (my first time planking remember) I got the hang of it. I cut a couple of strips of 1/16" balsa that tapered from 1" to 1/4". Then I cut a wedge off the 1" end down to 3/4" and then sanded the cut edge to a nice curve, leaving the other edge straight. After wetting each strip I glued it in place with aliphatic and pinned and clamped it in place, then same for the one on the other side of the centre longeron.
When it came to the fin, I made up balsa skins and glassed the inside face of them before epoxying one in place. I wanted the fin nice and rigid as it supports the tail. The fin is quite broad.
I had to plank the engine in take bit too, and blend it into both the fuselage and the fin.
Finally, I finished the planking and it looked good. I lifted it from the building board, added the formers and longeron for the left side, and planked that too. When finished planking (thank goodness) I gave it a rough sanding down, a bit of filler and a final sanding down, prior to glassing it.




The left side, showing the cut line where the engine access panel will be separated.


The right side, with a slot for the servo arm. The servo mount was added to the inside of a cut-out in the fin skin.


I added a bit of extra plywood to keep the circular shape of the join former.


The inside.
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Old 02-24-2021, 09:15 AM
  #28  
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Beautiful work. Looks awesome!
Old 02-24-2021, 12:27 PM
  #29  
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Thank you Viper, but it's a pretty rough bodge-up job when seen up close.
Back on the drawing board (screen), I'm trying to work out where everything inside goes, and how to get it there and hold it in place, with limited access.

My original plan was to glue the fuselage rear onto the middle bit, but access would be nice.
So I could make it removable, or put everything in from the front.
Old 02-25-2021, 11:37 AM
  #30  
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Some of the add-on bits of the aircraft caused a bit of head-scratching. I needed a pair of light dummy engine nacelles, preferably hollow to reduce drag, a fairing around the tailplane on the top of the fin, and a sort of rounded lump where the APU is mounted below the rudder. Balsa planking was not an attractive option, so what could I do with a hot wire on foam?

I cut two semi-cylinders out of blue foam, the closed cell type used for floor insulation. One was 2.5" diameter, the other 1.5". I glued two of these together to make a cylinder.
In the larger ones I cut a groove before joining the halves, then I cut lengths of the cylinder to the size of an engine nacelle.
I cut narrow circles from 1/8 birchply for the intake and exit holes and epoxied them on the ends
I used my belt-sander to shape the foam to the form of an engine cowling, finished them off with a sanding block, a bit of filler to correct errors, more fine sanding to get a smooth surface.


Two halves make a whole (cylinder).

Having a spare sometimes avoids having to scrap one and start again.

Then I glassed the outside with 25 gram (1 oz) glasscloth. When that was cured and trimmed, I fed the wire of my single handed hot wire cutter along the slot, reconnected it, and used it to hollow out the inside.


Glassed, then hollowed.

They're hung on the back so need to be light.

The smaller blue-foam cylinder was tapered at both ends, smoothed and glassed to be the fin-top bullet. An offcut was shaped to represent the APU housing, and more blue foam was made into a rudder.

The finished bullet fairing for the tail/rudder join, and the rudder (not yet glassed).

Old 02-26-2021, 02:01 PM
  #31  
alasdair
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The planked rear fuselage section needs glasscloth for strength, and to bind all the strips together. I covered the lower (fuselage) part in one piece form the bottom up and left that to cure.


Rear fuselage with the foam fin leading edge in place, sanded filled and sanded again. Also the APU fairing carved from foam, glued in place, filled and sanded smooth.


The rudder is just laid in place to check the fit at this stage.

The top part, including the fin and the engine intake, was glassclothed in one go from the top down, including the APU fairing.
The rudder was then fitted, but to get it in I had to lop a bit off the bottom because of the angled hinge line. I put a spot of retract oil on the hinge pin, then epoxied the hinge into the fin. When that had set I put epoxy right deep into the holes in the rudder then pushed in the hinges. The hinge line is well into the rudder.


I had to remove the bottom of the rudder to get it on.

A bit of rudder is fixed in place, right at the top. Some of it will be covered by the tail bullet fairing.
Old 02-27-2021, 11:40 AM
  #32  
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More work on rear fuselage.
The bottom part of the rudder was stuck back on and the rudder was glassed. So that's all the glass/epoxy done on the back end.


Bottom of the rudder re-attached and the whole rudder glassclothed.

That's the rear end glasscloth work done.

Next I separated the engine cover. When building the rear fuselage left side I had doubled up former F5, that is I glued in two copies, shamfered a little for taper, and separated by a wee bit scrap 1/32" sheet balsa.
So I took my thin razor saw and cut through the glasscloth and balsa sheeting into that 1/32" gap. The sheeting had not been glued to the centreline crutch, and at the top it was cut away, allowing the engine cover to separate from the fuselage. A little bit of adjustment with a Dremel sanding drum made sure it would clear the engine.

Engine bay and cover.


Engine fits nicely.
Still don't know how I will hold it in place though.
Would two dowels at the front and a magnet at the back be enough, d'ya think?

Last edited by alasdair; 02-27-2021 at 11:45 AM.
Old 02-28-2021, 01:51 AM
  #33  
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It would probably do the job. Could one of the dowels be exchanged for a screw, accessible from the front? You could also have the magnets by the side of the dowels, pulling it towards the bulkhead, and have a hook at the rear end?
Lars


Originally Posted by alasdair View Post
Still don't know how I will hold it in place though.
Would two dowels at the front and a magnet at the back be enough, d'ya think?
Old 02-28-2021, 03:22 AM
  #34  
alasdair
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Originally Posted by LN-JET View Post
It would probably do the job. Could one of the dowels be exchanged for a screw, accessible from the front? You could also have the magnets by the side of the dowels, pulling it towards the bulkhead, and have a hook at the rear end? Lars
After I glue the fuselage rear on to the middle (that's the plan) I lose access to the front of the mating former. So a screw away back there is not possible.
I lost faith in hatch magnets years ago after losing a canopy (first flight) on a foamie, but since then I bought some small but very strong magnets. Tempting.
Old 02-28-2021, 11:16 AM
  #35  
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Piano wire through a multi piece tube. No tools no chance of detachment. Not much flight risk from losing it completely but a major pain to remake
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Old 02-28-2021, 11:41 AM
  #36  
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Yes, thanks Dave! I hadn't thought of that one. I've seen it used and it looks great, but never used it myself.
I'll mull that one over, along with the magnets. I already drilled 2mm holes for dowels, and I have 2mm carbon rod stashed somewhere.
It's not a sport model subject to 9g plus, just a gentle fly around, right way up (mostly).

I don't suppose a magnet back near the engine will interfere with anything, will it?
Old 02-28-2021, 12:14 PM
  #37  
alasdair
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Back to the beginning again. I cut some foam panels, bored holes and left them lying around while I thought about skinning them.
First I had to install sleeves for the wing tube.
The plywood root ribs were first glued to the foam. The inner ends of the sleeves are held securely by the root ribs, and the outer ends are supported in holes in balsa and plywood uprights that were glued in over-size and sanded back flush with the foam. They will be glued securely to the skins when they go on.
Wing skins from 1/16" balsa., pieces stuck together with masking tape. Then I turned over, folded the joins open and squeezed in a little aliphatic glue, wiped the excess and left them to set.
Then I applied 50g glasscloth to the inside face. I dabbed some of the epoxy onto the foam (where there still is foam) and assembled the whole thing back in the sleeves with weights on top. Oh, yes, I also put a strip of carbon cloth along the line of the wing tube.
I suddenly remembered that I hadn't made holes in the panel for the servo wires.

Brass tube to drill a hole through from the join line to the undercarriage bay.

Paper tube for servo wire installed.

While that lot cures I'll make up the top skins.

Old 02-28-2021, 01:44 PM
  #38  
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Originally Posted by alasdair View Post
Yes, thanks Dave! I hadn't thought of that one. I've seen it used and it looks great, but never used it myself.
I'll mull that one over, along with the magnets. I already drilled 2mm holes for dowels, and I have 2mm carbon rod stashed somewhere.
It's not a sport model subject to 9g plus, just a gentle fly around, right way up (mostly).

I don't suppose a magnet back near the engine will interfere with anything, will it?
Just whether there is any aerodynamic high pressure inside/low pressure outside to blow/suck it off.
Old 03-01-2021, 01:55 PM
  #39  
alasdair
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The inner wing panels now have the top skins added, in just the same way.
Once the epoxy had set I sanded the leading and trailing edges flat, added balsa to the TE and carved a chunk out of the plywood root rib and the bottom skin to clear the undercarriage mounting (which sticks out of the fuselage root rib).
That allowed a trial fit of the wing onto the fuselage. I fitted the 1/8" dowel peg near the TE, the bolt through the root rib into its blind nut and of course the wing tube. It all fitted reasonably well so I used the fuselage as a jig to bore the hole in the foam for the short forward wing tube until it poked out of the LE foam. Then I epoxied in the sleeve, and the LE balsa with an extra dollop where it met the carbon sleeve.

It all feels very strong and very rigid.

The other end is the join line where it meets the tip panel, and that paper tube better line up with the one in the tip panel.
Old 03-03-2021, 04:03 PM
  #40  
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The Trident's outer wing panels took me back to good old fashioned model building, pinning the plan to the building board and pinning down balsa sheeting, balsa mainspars, balsa ribs (1/8" balsa laser cut in my garage), followed by top spars, spar webs, top sheeting.


Computer generated and laser-cut rib set.

The section was NACA 33012 at the big end (rib 1) and thinned down to the same basic section but thinned to 10% thick at rib 11, with 2 degrees of washout built in.


A nostalgia trip after all the foamie EDFs and painted-in-the-mould sleek ARfs.


So there are the two tip panels, with carved blue foam tips ready to add, and one aileron cut away.

Where the ribs were not sheeted I capped them with carbon, stuck on with cyano, which stiffened them considerably. I also glassed the foam tips.
Old 03-03-2021, 10:00 PM
  #41  
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Nice wood working skills there 👍
Old 03-04-2021, 11:53 AM
  #42  
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Thanks Dave, I haven't glued balsa sticks for a while.
Next stage in the mini Trident was the tailplane, built flat for convenience in 3 layers. The middle layer was 3mm balsa and a little ply, the outer layers were 4mm balsa and that was sanded away to a symmetrical aerofoil section. Except right in the middle were it was bolted flat to the plywood top of the fin.


I made the tip balance-bits bigger than scale.

After sanding in the section, plywood servo mounts were glued in to the centre.
And then the centre where the outer layers joined was reinforced with glass/carbon and epoxy. The tailplane (H-stab) was held to the fin top by two bolts forward and one aft into blind nuts.

Servo mounts added.

And centre joint reinforced.

The bullet fairing was cut away around the tailplane, and fin top.

The forward part was glued to the fin. The aft part fits around the elevator servos and will be held in place (somehow).

Then all the bits were roughly placed together for a photo call. Ta-Da

That's when I realised how big it was. Originally I had considered a hand launch model.
Old 03-04-2021, 12:41 PM
  #43  
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Aladsair,

That looks fantastic - great work.

Trident was my first experience of a flight on an airliner - and a cockpit jump-seat ride as well - LHR to EDI (Edinburgh) and back day trip when I was in the Air Cadets.


Paul
Old 03-04-2021, 12:58 PM
  #44  
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Was it a good trip? Good crew? Good views of fluffy cumulus, Forth bridges, Edinburgh? Or cloud and rain?
My first airliner was a Viscount, with the big windows and smooth Dart turbo-props, at age 6, flying Glasgow-London-Zurich on holiday.
And when I was twelve it was a BEA Comet 4B to Geneva.
WOW, the power, the accelearation, the climb!
About that time I saw some detail drawings in my father's drawing office of a new wonderful airliner with 3 engines, 3 of everything in fact. He was doing sub-contract work for H.S.

My Trident could be ready to fly - unpainted - next week. It's a worry. What can I do? What excuse can I make?
Maybe it should be painted, after all.

Last edited by alasdair; 03-04-2021 at 01:01 PM.
Old 03-04-2021, 01:02 PM
  #45  
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Too long ago to remember the details of the trip. At least 40yrs ago now.

Has this been a real-time build & post, or are you just posting the build that you started a while ago and catching up to real-time?

Paul
Old 03-04-2021, 01:17 PM
  #46  
alasdair
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Originally Posted by JSF-TC View Post
Too long ago to remember the details of the trip. At least 40yrs ago now.
Has this been a real-time build & post, or are you just posting the build that you started a while ago and catching up to real-time?
Paul
I started back in January. The first photo is dated Jan 2nd. That was the experimental cutting of the wing root panel, so I must have cut the templates a few days earlier. At first I was just trialing a construction method. But it quickly became a flying proof-of-concept model powered by EDF, and then the X45 called to me.
It was your Buccaneer build thread, and then Javad's scratch Phantom, that prompted me to start a Trident thread.
I am catching up with real time building.

How is the Buccaneer mark 2 coming along?
Old 03-04-2021, 02:52 PM
  #47  
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when i was growing up my neighbor built a full scale sopwith replica in his garage... pretty early he sorted that he was going to have to disassemble it to get it out.. you wont have that issue! You are doing great! thank you for sharing!
Old 03-05-2021, 02:46 PM
  #48  
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When I came across those twist/turn retracts (see post #6) I thought I should make provision for retracts, so the initial fixed gear was designed to fit the same space as the retracts.
I have since realised that there is nowhere for proper scale main gear to stow (4 wheels in line) without hacking out quite a lot of the fuselage, so fixed gear it will be on this model.
I used a bit of beech undercarriage block saved from another model, made up an undercarriage in 4mm piano wire (music wire in US), and added some 6mm pine to the sides of the carbon-reinforced plywood supports sticking out from the fuselage.

These bits assemble to fit the mountings of the retract units.

Fitted in place, screwed to the pine doublers.

There is a hole in the wing into which these slide.

The nosewheel on the Trident is offset to port, and retracts sideways.
Again, the mount plate was drawn to fit the retract unit, laser cut from liteply, and carbon plated on both sides.
I used a 2" wheel (scale would be 1.5") on an old nosewheel wire coil from an old crashed sport model.

Sturdy old wheel on 4mm wire nose-wheel coil, with tiller arm.

I took a couple of thicknesses of plywood, and a bit of steel top and bottom, drilled a 4mm hole and bolted them down to the ply/carbon mount plate glued into the front of the centre fuselage.
It might have been neater if designed that way from the beginning, but I was making it up as I went.
A steering servo was added, and a linkage, and now we have a steerable nosewheel sticking out through a hole in the glassed foam fuselage.


Crude, but seems to work

Maingear and nosewheel fixed. What's next?

It sits a little nose high. maybe I'll change to a 1.5" nosewheel if the grass is smooth enough, bey hey! It'll help take off, won't it?

Old 03-05-2021, 02:53 PM
  #49  
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I would have junked the offset nose leg position...or at least flipped the wheel over to make it more central. I think when you turn left it will dig in.
Old 03-05-2021, 03:05 PM
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Originally Posted by Dave Wilshere View Post
I would have junked the offset nose leg position...or at least flipped the wheel over to make it more central. I think when you turn left it will dig in.
Dave, The noseleg offset to port and retracting sideways is so significant a characteristic of the full size aircraft that I wanted to try it on the small model to see if it would work. If it does, then when the big show model is built it will have the same offset leg, with confidence.
If it turns out to be a problem, I'll reconsider.

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