Scale Soaring UK

Im just planning to build a Salto at about 1/5 scale from scratch using ply/balsa and just beginning to cad up ideas. So I’m thinking of something around 3m span fully sheeted wing and planked fuselage. This will be my first attempt at planking but have constructed built up wings from scratch a few times. I am going to CAD the parts and get them laser cut.

A few immediate things airfoil - regroups have some suggestions and anyone have particular recommendations. So far I was thinking of hq25/12.

The other item giving me more concern is the canopy. It would be great to buy off the shelf!

Andy - I see no-one has commented on your project yet! There is absolutely no reason why you can't make a great job of this but you ARE setting yourself quite a task doing everything from scratch. I've never done a complete scratch build but have heavily modified from plans - it can get quite scary as you really are getting into model ENGINEERING and need to make sure stuff is strong enough as well as looking right. Great thing about 1/5 scale is everything really is a lot smaller and lighter so i think the engineering side is less critical. How much of this type of designing and building have you done? I'm sure folk will help but equally don't want to patronise you if you are confident you know what you are doing!?

Nigel
yes i like a challenge and looking for help/observations etc on the way! the level that im looking is more semi scale, as i know i would struggle with finer details, and im likely to simplify details that i know cant handle or will just make of a mess trying. This is where i find drawing out the plan/parts to help. it probably would be a good thing to start with a short kit to get an idea of the thicknesses of parts etc but for some reason im keen on a salto, and that i could not find one. I find drawing somewhat theraputic, so even may just draw it out and park it would not really be a disaster for me. You are right about the scale being less of a concern. I dont have extensive building exp - started with kits chris foss a 2 mRES then a couple of slopewings from balsa built up with spans up to 2.5 m - this was more of wing planform selection. airfoil selection drawing out, laser cut then assemble, and then Jarts using lost foam for fuselage. Certainly no scratch building for scale/semi scale on my list. Compared to what i have done so far the fuselage planking is new, and i have some concern over the construction of the wing particular toward the tip given its thickness. Im busy drawing away.......see where this goes...

well not much time available to progress although slowly drawing out formers and fuselage outline. Managed to get a canopy from sarik hobbies (small salto version) which seems to be pretty much 1/5th scale.

Formers currently thinking 3 mm ply, and 3/32 planking. the spine to fuselage formers thinking 3 mm ply. Not sure if i should build two flat halves then join, or build one flat and lift from the board. Plenty of time to decide that! For the formers still to decide and draw the stringer (least thats what i think they are called) or perhaps run a carbon tube on either side. For stringer this seems from other builds to be spruce(?) and 3/8 by 1/4.

Any comments on the dimensions would be most welcome.

Ho andy I would go for it .nice to see someone having a go. best of luck will be watching. Roo

Interesting project Andy and good luck with it. I like the Salto (I have the Valenta one) and have toyed with the idea of making a third scale or even 40% scale one before I saw sense. I think the Salto might be quite a challenge to make with the balsa planking technique because of the complicated compound (and in particular the concave areas) in the fuselage - not to say it's not possible and as you say you like a challenge!

I don't think you'll go too far wrong with that aerofoil section (I think the Valenta is HQ25)

Simon

Well, as a rest from clearing snow had a test section of planking. Made up 5 formers and 3/32 planks. Learned a few things doing this. Need a balsa stripper, now on my shopping list. Order of planking - top bottom middle and infill?? Warping of the structure - that will be a challenge to manage especially if made in two halves. I think two flat sections then join together might be best or make a jig to holder formers to allow planking either side at once.

Andy, would it have been easier to sheet it in sections rather than plank it, probably wetting the balsa first to get it to conform to the curves of the fus?

Have you glued together just a section of the fus, and did you jig it or just "freehand" assembly?

I'm interested to see how you tackle this as the shape is not dissimilar to my Fauvette fuselage which is also at 1/5 scale.

If it's any help, this is how I built my 7th scale Gull fuselage, sheeting the rear with 1.5mm balsa sheet, and the front with 2.4mm balsa planking to allow extra for shaping up... The half-shell method was used...

Hi thanks for the responses. this was very much scrap balsa and a free hand assembly just to try out planking as i have not tried this before. Im still drawing parts out, but just wanted a break.
Chris thanks for the suggestion and pictures - very useful

well all the parts have been drawn. To finalise just thinking what i should use to skin the wings; i have balsa sheeted before but see many use ply. Looking at either 0.8 mm or 0.6 mm ply. Quite a big cost difference so want to make sure i make the right choice. I have made a trial wing panel and tested sheeted it with a spare piece of 0.8 mm ply and quite impressed with the finish. I was going to go with the 0.8 mm - is this a reasonable choice for a 3 m span?

Oooh, bad choice IMHO... Hard 1.5mm balsa works not only for small models but large models too....

Absolutely - too heavy and unnecessary for a 3m model; 1.5mm balsa will be fine but if you prefer to go down the ply road then 0.4mm at most.

thank you - balsa it is!

Well parts received in the post. No excuses to start.

Made a start. A few ribs in place and soon one side planked. A few modifications to the cad file needed and think I will try slightly narrower planks when I turn it over.

Progress on planking fuselage. Changed the width of the planks for the last two thirds which made things easier. Still learn by your mistakes and picked up a few additions to the parts I drew.

Bit more progress. Wings I’m building in two panels as limited by building board. One inner panel is skinned on both side the other one side. Had a few issues trying to get the balsa in full contact with the ribs at the trailing edge where the airfoil curves up. Trial fitted one to the fuselage and seems a good fit.

Outer wing panel now underway and balsa sheeted one side. Looks a bit plank like. Taper should be more evident once aileron is constructed.

Some progress with fuselage. A little filling and beginning to sand. Beginning to take shape. So far just a light sanding. Are there any particular suggestions how thick the sanded planks should be?

Made a silly mistake with the vtail. So will make from scratch a bit later.

In the process of sanding the wings - on obechi covered wings i have in the past used ezecote which has given a good finish when covered. Is it worth doing the same with the balsa skinnned wings? Welcome opinions/advise. thanks

Could not resist carpet flying

Nose block added and sanded to shape. Made a hollow inside to include some lead. Trial fitted wings to get a very approx nose weight to balance.

I hate canopies. Say no more

Evening all - i am even less a fan of canopies now. Since glueing ply around the base of the canopy the ply base has warped so now have 5 mm upstand at the front. everything was fine to that point. I think i will start again, but any suggestions if it could be straightened. the base is 3 mm ply - which has triangular strip to guide the plastic canopy. then i have 1/64 ply as a trim. at best im hoping to save the plastic canopy but before dismantling wanted to see if there are suggestions (other than get someone else to do it for you........ )

I've always found it best to fit the canopy with the frame firmly attached to the fuselage?

Chris thanks. Now the moment is why did I not do that in the first place.

Like this:

I use Pacer canopy glue, which dries clear; handy in case of excess application!...

Managed to reconstruct without damaging the canopy. Now straight and fits well. Just waiting for canopy glue to complete. Made some winglets following a posting in RC digest. Now starting covering wings. Will post a few photos later.

Second attempt. Much improved. Still room for improvement. Next.

replacement tail constructed from blue foam with balsa veneer. previous version was a bit thick and heavy. saved 60 gms.

nice morning ironing. both wings covered. v tail covered. now thinking if to put film on the fuselage or paint.

getting close to completing the salto. a few pictures attached. spoilers - decider to try a sliding L mechanism as posted on RCGROUPS. next time i might keep it simple They work fine but need a lot of adjustment.

AUW. 2600 gms.

Nice

finally got around to maiden the Salto in a small gap in the c weather. spent most of the flights adjusting nose weight. tried with and without winglets- with winglets it seemed to perform better. Spoilers are very effective. Had a new frsky g8xr receiver but had poor signal so this shortened the flights.

Barry thanks for the offline suggestions. The poor signal turns out to be a loose antennae on my tx. a few flights on the slope under the belt and a few more improvements needed.

That's a great job to capture the Salto's shape in wood - well done!

it was enjoyable building it and learned a lot on the way. Tempted to improve and do another. Since have built a Petrel from a short kit which gives good ideas for building. Also changed and improved the canopy. Really needs more air time this year.