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Trident airliner scratch build

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Trident airliner scratch build

Old 03-06-2021, 02:10 AM
  #51  
Dave Wilshere
 
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The bigger aeroplane will have stiffer wheels & legs, but I guess it will give you a head start. If it works on the small should be fine on the big one.
Old 03-06-2021, 01:49 PM
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alasdair
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A quick addition today: covered the tail plane (H-stab).
First I mass balanced the bare elevators, with lead in the aerodynamic balance.
The servo mounts were drilled for the mounting screws, the servos screwed in place, the elevator horns put in place temporarily, the fairing placed on top and it all fitted.
The elevator hinge-points were glued in to the elevators, eventually, after a lot of filing and fiddling, and adding half a drop of retract lube to the hinge pin.
White kero-proof film was applied to the elevators.


Servos in place.

It all seems to fit.

The hinges were glued into the tailplane, and then the tailplane was covered, also all white apart from the leading edge.
Then the leading edge was wrapped around with sticky-backed aluminium tape, not an easy job. That tape sticks to the first thing it touches, but once smoothed down it looks OK, if a little asymmetric. I had been planning on doing the wing LE the same way, to represent the slats. But I need a plan B.


Tail finished, covered in white, LEs aluminium like the full size. Servo linkages done with short rods and ball links. Each will have its own Rx channel for a bit of redundancy.
Old 03-07-2021, 03:25 PM
  #53  
alasdair
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I'm getting there. It's taking both shape and colour now.
Post #42 had a photo of the model with the wing inner and outer panels tacked together. Since then I have glassed the panel join to carry the bending loads and they seem OK.
Then the wings were covered with film.
The wings of FB in the museum had the ailerons and flaps painted pale grey like the lower fuselage, the wing tips painted silver, the slats aluminium and the main part of the wing bright red (top and bottom).
I like the red wings. Easy to see at a distance, unlike pale grey (Scottish sky grey).
I cut out and covered the ailerons first, then the flaps. I didn't have any grey film but made do with silver Solarfilm, which is not kero proof. But the model is not built to last. If it lasts, I don't mind recovering.

Then the main bit of the wing was covered with red film.
Finally, as an easy alternative to aluminium self-adhesive tape, I made the slats from more silver film.

Silver film was used for flaps and ailerons. The tips were supposed to be silver anyway. The aileron is just taped in place.

The aileron servos were installed and the ailerons were top hinged for simplicity.
For the wing fences I drew a line marking their position, and scored through the film using a fine soldering iron against a steel straight edge.
I took a piece of cardboard and using cut-and-try, cut-and-try, cut-and-try eventually fitted it to the shape of the top of the wing. I then made two wing fences from 1/32" plywood and epoxied them in position.


Underside showing the leading edges, silver film to simulate slats.

Short aileron linkages.

Wing fences glued on and painted silver.
Old 03-08-2021, 04:00 PM
  #54  
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Access is my problem.
My plan was to glue the rear end of the fuselage onto the middle bit before painting, leaving only the hole at the front, behind the cockpit, to get at the fuel tank, the UAT, the fuel pump, the fuel tap, the receiver and its satellites, the refuelling point and fuel vent.
Still sticking with the plan so far, I have made a mount for the fuel tank right near the rear, over the CG.
I have a mount for the UAT a bit further forward, as that helps CG-wise.
I have another mounting plate that can take the Rx, the fuel pump and the fuel tap.
And yet another mount for the battery that will place it under the cockpit right forward.
The cunning part (if it works) is to join them all together in a single piece that can be placed in the aircraft, (inserted through the front hole) and simply secured in place.
So here is the fuselage insert, laid on top of the middle fuselage section.

All the mounting plates are laser cut liteply.

The whole thing is based on a couple of 6mm carbon tubes. The rear mount, for the fuel tank, is reinforced in its middle section with carbon cloth and epoxy resin, which wraps around the carbon tubes.
The other two mounting positions have lightening holes and are reinforced with glasscloth and epoxy.
The front position has carbon/epoxy reinforcement and will hold the batteries right forward under the cockpit floor.
It will be bolted to the former F1B at the front of the fuselage.

Right at the back a pair of dowels will slide inside the carbon rods and hold their rear ends securely in place. That's the plan!

One of the dowels that will hold the rear of the carbon rods in place. The hole in the foam below is for the aileron servo wire.


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Old 03-09-2021, 01:49 AM
  #55  
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Access would be no problem if you have a cutout for the wing in the center of the fuselage.
Boeing 727 (4)
Boeing 727 (5)
Your Trident build looks awesome! A Trident 3B would be even more striking
Old 03-09-2021, 03:26 AM
  #56  
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Originally Posted by fumus View Post
Access would be no problem if you have a cutout for the wing in the center of the fuselage.
Boeing 727 (4) Boeing 727 (5)
Your Trident build looks awesome! A Trident 3B would be even more striking
Many thanks for that. I have never seen a detailed build thread for Herr Rauch's 727, just photos of the moulded parts.
I was aware of course that he had done one and made it available as a kit, and I remember years ago looking at the kit and deciding that,
1. I didn't want a 727
2. I couldn't dress it up to look like a Trident.
3. I couldn't do all those moulded parts for a Trident.

However it has given me a much better idea of how his 727 kit was put together. I didn't know that he had a white foam cylinder covered with sheet balsa. And all those cut-outs. And the engine was a 70N, with a tail-pipe. [the second hand Tristar I nearly bought years ago was for an 80]
A one-piece swept back wing must have been quite a size (81 inch span), but I can see that it made fitting the main gear retracts easier.
A one piece wing would have been easier for my little model, but no use for the one seventh scale one, and the wee one is a try-out for a bigger one.

I notice that the bullet fairing on top of the fin is fixed, and the AMT moves around it.
On the Trident the fairing is fixed to the tail and moves down over the fixed part of the fin.
I also note that he has not used leading edge slats, which is reassuring as I will not either, and he has quite simple flaps, not Fowler flaps on tracks.
I just watched the videos on the website too, and am pleased to see it fly with no sign of dutch roll.

Thanks again for the link, very interesting.
Old 03-09-2021, 07:38 AM
  #57  
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Originally Posted by alasdair View Post
.....
I notice that the bullet fairing on top of the fin is fixed, and the AMT moves around it.
On the Trident the fairing is fixed to the tail and moves down over the fixed part of the fin.
......
I think it's very similar to the Tupolev 154.


Pic can be found on the site of Norbert Rauch
Old 03-09-2021, 09:31 AM
  #58  
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The Trident has both. The AMT is driven by the elevator control.
And hinged on the back are elevators that move also, in the same sense (i.e. they are not a balance tab) and are coupled to the tailplane movement.
On the Tu 154 the fairing ahead of the fin is more prominent, but as you say the arrangement is similar.
Old 03-09-2021, 03:40 PM
  #59  
alasdair
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I have mounted the dummy nacelles on the back now.
First I cut holes in the rear fuselage on the nacelle centrelines.
Then I cut short lengths of 6/4 carbon tube (6mm outside, 4mm inside dia) and glued them into the holes with a length of 4/3 mm tube inserted while the epoxy cured to keep the outers in line.


carbon tube guides glued in.
Then I made the mounting pylons.

I hot wire cut a bit of blue foam to a thin symmetrical section, and cut one edge to fit the nacelle and the other to fit the fuselage.

A bit of sanding made them fit reasonably well (it's only a proof of concept model).
A foam pylon was epoxied to each nacelle.

This was then held against the fuselage while the 4mm carbon tube was bored through the foam into the centre void.

One carbon rod was epoxied into the front hole of one nacelle, and the other was epoxied into the rear hole of the other, and the pylon bits were glassed with scraps of glasscloth and epoxy.

epoxy/glass stiffened them up nicely.
By doing it this way I can concentrate on lining up one rod at a time through both sleeves.

A 4mm collet on the free end of each carbon tube, inside the nacelle holds it on well enough.

And they fit well enough.




Last edited by alasdair; 03-10-2021 at 07:13 AM.
Old 03-09-2021, 10:15 PM
  #60  
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Super build!
Nice work, sir!

paul
Old 03-10-2021, 03:13 PM
  #61  
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Some bits and pieces to report.
I added a bolt (M6 plastic) that engages in a blind nut at the front of the battery mounting tray and holds the nose in place, pegged with four short 3mm dowels.

I cut a little off the nose. Its place is taken by a big plastic washer and bolt.
I made up the fuel tank, a Dubro 40oz. (1.2 litres) with a heavy brass clunk on the end of a bit of Tygon tubing and a bit of brass tube to prevent the clunk form tucking forward. Only two (big bore) brass tubes through the bung, one vent/overflow and one to the UAT.

Nice heavy clunk.
That tank goes on the back platform, and on the one ahead is the UAT that it feeds.

A small 2oz UAT with small bore fittings should be adequate.
A block of firm foam was hollowed out for the Spektrum 9020 receiver and will be attached to the platform just behind the nosewheel.
I decided to test run the engine outside to get familiar and iron out any problems, once I have put all the pieces together on the carbon tube insert.

carbon reinforcement on the underside of the fuel tank mounting. The two little holes were going to be for the pump, but there's a change of plan.
Old 03-11-2021, 03:11 PM
  #62  
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Time to install all the innards of the aircraft, but since its skeleton is removable I get full unrestricted access as I install it all.
First of all, right at the back behind the main fuel tank is what Gaspar of Xicoy calls the "hub" where all his stuff connects. One wire goes aft to the engine, while forward goes one to the pump, one to the receiver and one to the data terminal where I can read what it's doing. Also running aft to the engine is a single 4mm fuel pipe.

Fuel tank over the CG, with the Xicoy "hub" connection block behind.
A bit ahead of that I mounted the 2 oz UAT that has a feed from the tank behind, and a fill on top. From the front is the feed to the engine. A Spektrum satellite is attached with hook&loop (velcro).

next along going forward is the Spektrum Rx snug in its mounting. The satellite on top will be tacked to the roof above.

The fuel pipe from the UAT comes to a tap this side, round to the Xicoy filter in front, then.....

.... to the pump on the other side and straight back to the engine.
The fill and vent pipes come forward past the Rx to connections near the nose gear, behind the battery.

That's the lot, ready to connect one pipe and one wire to the engine and give it a run.
I had by this time run full power then turned the power down to 30N (quite enough I expect). After switching off the Tx the engine cut after two seconds.

Last edited by alasdair; 03-11-2021 at 03:15 PM.
Old 03-11-2021, 03:26 PM
  #63  
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Poor engine and radio! Long overflow lines are bad news (as are clunk lines with hard pipe inserted with non absorption clunk) those remotes working in a nest of extension wires, you are making everything work hard!
Old 03-12-2021, 02:14 AM
  #64  
alasdair
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Hi Dave, thanks for the advice.
I could take the vent pipe back with the feed to exit near the engine access panel. Would that be better? Still longer than my usual vent, but possible. I didn't know long vent lines were a problem.

I had been under the impression that an absorption pickup in the UAT made another in the main tank unnecessary, and caused more flow restriction. Does that not matter? I could change it for a pleated paper or felt clunk if you think that is better.
And I could take out the 2" or so of hard pipe just before the clunk. I have been told it's a good idea (to avoid having the clunk flick forward in a sudden stop). I have had that problem a few times on glow engined models in the past and it seemed sensible. It is large bore brass tubing, same as in the tank bung.

The remote seen on top of the Rx will be mounted high in the fuselage. The one attached to the UAT has some servo wires passing. They could pass the other side of the UAT.
And/Or I could wrap the wires with aluminium foil. I had to do that on my Wren 54 as the RPM sensor was giving false readings, picking up interference from the glow or starter leads, but a wrap of kitchen foil cured it.
But all the signals on this engine are digital.
My installations are never neat. I envy neat installations.
Alasdair
Old 03-12-2021, 02:28 AM
  #65  
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Would the tank vent be better placed in the fuselage bottom adjacent to where the engine access panel separates?


I could put the vent in the front of the access panel or the fixed part just ahead.
Old 03-12-2021, 03:27 AM
  #66  
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Originally Posted by alasdair View Post
Hi Dave, thanks for the advice.
I could take the vent pipe back with the feed to exit near the engine access panel. Would that be better? Still longer than my usual vent, but possible. I didn't know long vent lines were a problem.

I had been under the impression that an absorption pickup in the UAT made another in the main tank unnecessary, and caused more flow restriction. Does that not matter? I could change it for a pleated paper or felt clunk if you think that is better.
And I could take out the 2" or so of hard pipe just before the clunk. I have been told it's a good idea (to avoid having the clunk flick forward in a sudden stop). I have had that problem a few times on glow engined models in the past and it seemed sensible. It is large bore brass tubing, same as in the tank bung.

The remote seen on top of the Rx will be mounted high in the fuselage. The one attached to the UAT has some servo wires passing. They could pass the other side of the UAT.
And/Or I could wrap the wires with aluminium foil. I had to do that on my Wren 54 as the RPM sensor was giving false readings, picking up interference from the glow or starter leads, but a wrap of kitchen foil cured it.
But all the signals on this engine are digital.
My installations are never neat. I envy neat installations.
Alasdair
I always go out the bottom of the aeroplane as close to the tank fittings as possible. The long length of tube makes the pump work harder as the air going in to replace the fuel has more resistance in a long tube unless you can step up the size dramatically.
The issue is the main tank will not provide constant fuel supply, so the bubble trap will rapidly fill with air. A non filter centre in the hopper tank and filter/cavity clunk in the main would be ok as it would keep the hopper tank full-any air around the edges should not have a a route into the engine.
Glow silicon tube kinks and bends easier than tygon, I have never run a fixed piece of pipe in an open tank vessel and have never had a clunk stick forward. We make high flow felt clunks for Jet use.

Some separation from the wires give the aerial wires a chance of picking up all the data coming in.

Wiring is an art form

​​​​​​ Dave

Old 03-12-2021, 02:39 PM
  #67  
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What is the best orientation for a fuel vent pipe?
Sticking forward (into wind)
Or facing aft (downwind)
Or straight down?
And why?
[In the past I have mostly gone for straight down, and had a nipple sticking out that I could cap for transport/storage. And after a couple of embarrassing incidents I include a "Remove before Flight" flag.]
Old 03-12-2021, 03:33 PM
  #68  
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To a degree the position I use depends on the fuselage shape. I’ve seen people put overflow fittings just in front of the air intake and they wonder why there is fuel everywhere each landing. Most of mine end up 90 degrees to the flight path, but generally to one side. So on your round airliner fuselage between 4 & 5 or 7 & 8 O’clock so it’s not lower that the bottom of the fuselage in the event of a gear up landing and also so I can see/access it. I always switch on/prep my models from the Left, so the fitting is below that side. If you can angle forward that’s great, definitely not angled back. If the vent line reaches the top of the tank in a loop it won’t siphon on the ground.
Old 03-13-2021, 02:06 AM
  #69  
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Originally Posted by alasdair View Post
What is the best orientation for a fuel vent pipe?
Sticking forward (into wind)
Or facing aft (downwind)
Or straight down?
And why?
[In the past I have mostly gone for straight down, and had a nipple sticking out that I could cap for transport/storage. And after a couple of embarrassing incidents I include a "Remove before Flight" flag.]
It looks on this plane that the fuel vent pipe is simply straight down and located below the engine nacelle. See at 0:07 on this video:

Old 03-13-2021, 05:26 AM
  #70  
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Originally Posted by fumus View Post
It looks on this plane that the fuel vent pipe is simply straight down and located below the engine nacelle. See at 0:07 on this video:
Yes, good video. I had a look at the Rauch Airliner website again, I didn't know he did a VC10-ski
It seems Norbert Rauch's Il-62 has a wingspan of 2.7m, 3.32m long and he quotes a weight of 12kg, but it's not clear if that's the turbine of i.c. prop driven original version.
The one in the photo has a pair of Wren 44 gold turbines in the outer nacelles (where the piston engines were fitted also).
I see in the video that the fill point is on the fuselage side under the starboard nacelles, and you're right, the vent/overflow is under there somewhere. There's a bottle to catch the overflow. I think I'll copy that too.
His model flies nice and slowly (compared the the usual screaming sport jets), and by the way the nose bounces along on take off, hardly touching the ground, I'd say the CG must be close ahead of the main undercarriage.
Old 03-13-2021, 05:33 AM
  #71  
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Hi Dave, Thanks for the advice again. Pretty much what I usually do too. I normally vent straight down from the bottom (though I have had traces of fuel escaping and blowing back along the fuselage bottom). Sometimes, like on my Jetlegend Grippen I used a bit of brass tube pointing sort of down and forward.
So I made up my mind and here it is. The vent is on the access hatch, just off centre and pointing a bit forward.



And I settled on two carbon dowels and a little screw to hold the hatch on.

Last edited by alasdair; 03-13-2021 at 03:03 PM.
Old 03-22-2021, 11:26 AM
  #72  
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It's been 9 days since I posted in the thread, and I've made amazing progress.......................NOT
I have dithered and dallied, diverted to plan other projects, thought about paints, considered not paining, just flying, but eventually yesterday I took the irrevocable plunge and glued the back end on to the middle.
A bit of 5 min epoxy and the deed was done, then the join was wrapped with a bit of glasscloth and epoxy.

Looks OK after a bit of rubbing down of the overlap.
Now I have gone straight into the paint job, a bit of primer on the nose section, nacelles and tailplane fairing (already rubbed back) and the first coat on the rear section. The middle bit around the wing roots needs a trifle more preparation then it'll get primed too.

now, should I fly it in primer? I'll decide in a week, or two. Or maybe I'll prevaricate a little more.
Old 03-24-2021, 06:48 AM
  #73  
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I hate spray painting. I hate spray painting. I hate spray painting.
I do love spray painted models, if they come out of the box like that - CARF painted in the mould models are fantastic.
Last time I sprayed a model (it was a Keil Kraft Intruder sport aerobatic model, built from a kit around 1984) I swore never to do it again, though the spray gun lay unused for many years until I eventually threw it away.
I was sure I'd never do it again.
Yet here I am, with rattle-cans, trying to do a facsimile of BEA's red square scheme of the 60's. It won't be pretty.
Rough as old boots is a fair description, but at a linear scale speed of 1200mph it should bear a passing resemblance.
Old 03-27-2021, 08:32 AM
  #74  
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Right, last little bit.
I glued some ceramic paper insulation to the inside of the engine mounting to avoid getting the inside burned by the hot engine parts. Then I fitted the engine and connected the vent fitting and closed it up.



Using my Xicoy CG weight and balance gadget I found that with a 2650 mAh lipo fitted the all up weight (landing weight with full UAT and a little in the main tank) is 3.32 kg (7.3 lb) and the CG is 11 mm (0.43") ahead of my target calculated point. I was aiming for 55mm ahead of the main wheels and ended up with 66mm.
I think I'll fly it at that and then consider a lighter battery or moving the battery back to just behind the Rx if I want the CG further aft.
I started with my heaviest battery, a 5000 mAh right forward and it was very nose heavy.
The engine manual recommends a "2S LiPo or 3S LiFe >1000mAh" but 1000 mAh sounds a bit light to me, but I might try a 2200 with a high "C" rating.

Last edited by alasdair; 03-27-2021 at 08:56 AM.
Old 03-27-2021, 09:52 AM
  #75  
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That's it until I fly the Trident. I took it outside and fully assembled it for a photocall.







I have a few details listed to add, but I keep remembering it's only a proof of concept model.
My next report should be about flying it. Fingers crossed. I really hope I don't have to report a smoking hole in the ground and a damaged X-45

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