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1/4 scale swift kit - help please

Anything to do with gliders & gliding.
Cain

1/4 scale swift kit - help please

Post by Cain »

Hi there

I have just acquired a beautiful kit from a BMFA ad.

It is a 16 year old untouched kit and complete without instructions. The main issues I can see are;

Fixing the wings in the correct place/incidence (which I plan to do by upscaling from a drawing as best as I can)
creating a fairing (which I plan to do by adding balsa to the wing roots and shaping)
Glassing, filling and spraying the wings (which the gent I bought it off suggested was needed for rigidity)

Please if there is anyone out there who can help advise I would be indebted
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chris williams
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Joined: 10 Mar 2015, 10:50
Location: Blandford Dorset

Re: 1/4 scale swift kit - help please

Post by chris williams »

Looks a lot like the old Mibo Modelli Swift, although I don't think that was as big as 1/4. If it is, then you're in for a treat. Is there a manufacturer's name anywhere on the model?
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Peter Balcombe
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Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: 1/4 scale swift kit - help please

Post by Peter Balcombe »

Hi Cain, welcome to the forum.
I’m sure there will be others who will chip in, but my thoughts are:

That appears to be a nice kit & presumably the brakes have been installed by the manufacturer.
If 1/4 scale then span should be just over 3m.
If the kit is 16years old, then it it possible that the brakes/aileron servos were originally intended to be in the fuselage, whereas it is now easily possible to fit wing servos using modern micro/thin wing servos, taking just the servo wires into the fuselage.
Yes, I would agree about glassing the wings using lightweight (25gsm) cloth & either laminating epoxy resin or a good water based alternative.

You will need to set the wing incidence at 2 - 2.5 degrees positive with respect to the tailplane.
Fix the wings & tailplane in the scale locations if possible.
The wing joiner may well be a flat steel strip/brass box type (can’t see from photo), but looks to be a single joiner with wing tubes already fitted at dihedral angle.
You will need some kind of wing retention system. Multiplex Unilocs are a good means of doing this as long as both sides of the joint are rigid. The downside is that you need to remember to have the plastic disassembly aid with you when de-rigging the model, but it does give a nice ‘click’ attachment which will undo in the event of a less than perfect landing.
Depending upon the tailplane/elevator arrangement, the fixing/pitch control arrangements need to be considered.
The original Swift had a conventional tailplane/elevator arrangement & if retains a scale appearance you will need to connect the elevator drive inside the fuselage. I suggest a square elevator half connection tube going through a slot in the fuselage which makes it easier to get a solid connection to an internal horn. Access would normally be via the rudder post aperture. The tailplane could fit using round or square tubes & joiners to allow easy removal.

Hope this helps,
Peter
Cain

Re: 1/4 scale swift kit - help please

Post by Cain »

Modellbau Steinhardt, I understand the manufacturer is retired :-)
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Peter Balcombe
Posts: 1399
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: 1/4 scale swift kit - help please

Post by Peter Balcombe »

A little info. is available on the web if you search for the manufacturer, but you probably need to understand German to get much more than HQ1.5/9 wing section & 4.5Kg weight.
Cain

Re: 1/4 scale swift kit - help please

Post by Cain »

Chris and Peter, thank you very much for your replies and welcome.

Regarding wing retention, there are captive nuts embedded in the wings, I guess these are for a grub screw, I will grind a flat into the steel spar (round 12mm rod) for the grub screw to locate into.

Thank you also for the info regarding incidence angles.

Regarding the the water based alternative to epoxy, I have not come across this before and will look into it, is there a compatible light weight filler (for water based or epoxy) the only one I have found is a marine based epoxy filler from Germany.

I am sure I will be contacting you again regarding tailplane fixing and elevator servo position. Looking at photos from topmodel may also give some inspiration

One other thought and question is regarding the addition of flaps - looks like X models version has no brakes but uses flaps and the top model version has both. The wing in this kit has been milled to take ailerons only - due you think it would be worth going to the extra trouble to cut and incorporate flaps - mind you I would need a lot of persuasion as doing it nicely would be difficult

Thanks again
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Peter Balcombe
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Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: 1/4 scale swift kit - help please

Post by Peter Balcombe »

Cain,
I wouldn’t recommend filing any slots on the joiner bars as you need the wings retained by the grub screws during flight, but able to slide out if a tip hits the ground on landing. If the wings are too fixed then you are very likely to get significant fuselage/wing root damage when ‘something has to give’.

I tend to use a lightweight car body filler type filler called BigBoy available from ProperJob. A lightweight version of Pollyfilla is also available.

Note that if your wing are foam cored then you mustn’t let any solvent get to the cores as it will ‘eat’ the foam.
Use only white glue, aliphatic, epoxy or similar if there is any chance of it getting into contact with the foam.

I wouldn’t worry too much about cutting out flaps as you will need to face the cut edges with balsa & can fill any small gaps & sand flush before glassing. Everything should then be hidden by the glassing/paint finish.
You would obviously need to make additional servo mounting holes for the flap servos & link up the servo cables to existing access apertures.

Looking more closely at the Swift tailplane, this is a normal arrangement, but fitted so far back under the rudder that it ‘bolts’ straight down onto the rear fuselage. The elevator appears to be continuous, so easy to fix a horn directly into its lower surface within the fuselage to connect via pushrod to forward fuselage mounted servo if necessary.
Depends where the rudder hinge line is with respect to the front of the tailplane as to whether the rudder drive can also be hidden.
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Simon WS
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Joined: 18 Mar 2015, 11:39
Location: Kent, UK

Re: 1/4 scale swift kit - help please

Post by Simon WS »

I think I would go for more like 1 - 1.5 degrees wing incidence personally as it is an aerobatic glider and you will improve its efficiency and aerobatic qualities (and need less nose weight) I had a Mibo Swift at 2.5m wingspan and it was brilliant (it's not that model as the Mibo Swift had the roots already moulded in).
Your model should be at least as good with that wing section.
Don't cut in flaps! It is not standard and not necessary with the very effective airbrakes you have fitted (the Mibo Swift did not have flaps as per the full size and landed beautifully with the airbrakes only)


Simon
Cain

Re: 1/4 scale swift kit - help please

Post by Cain »

Thank you again for you advice Simon and Peter - definitely worth me asking before I take a knife and saw to it.

I will post more pictures as I start to make progress. Found the big boy (also stocked at amazon for a premium)

Best regards
roo Hawkins
Posts: 557
Joined: 18 Mar 2015, 20:12
Location: Northamptonshire

Re: 1/4 scale swift kit - help please

Post by roo Hawkins »

Hi I have swift at 1:3-5 at 3.7 span lovely glider I was worried about the weight at 9kg.but it is no problem. My wings are quite bendy but they seem to be OK in flight. I have modified the elevator to one piece as the canterlever tips kept breaking off in bracken and long grass. I have just rebuild mine from a bad crash at.middle wallop. I Have covered the wings in sign vinyl cheaper and a lot stronger than film and looks like glass. What are you doing for a wing joiner? ?
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