Topic: Stearman - Ziroil 77" with Seidel 770ST radial

Hi guys and gals
  I have made a purchase today from Belair kits, its a large bag of small part masquerading as a kit (I was warned! LOL) looking forward to the challenge but my building experience is limited, I'm more used to large foam wings and large fiber glass parts.

So if any one out there has any info or advise it would be much appreciated.

Ill post pics as I go and would like to say thank you in advance for all the hint and tips I'm sure I will receive in spades.  

yay, watching with interest...

So am I, just start by sticking part A to part B and so forth and eventually you should end up with something that that looks like an aeroplane. 

So am I, just start by sticking part A to part B and so forth and eventually you should end up with something that that looks like an aeroplane.  

Is that how you build a Boeing Star man...  

 

So am I, just start by sticking part A to part B and so forth and eventually you should end up with something that that looks like an aeroplane. 

Good advice Star Man, but having trouble finding part A at the moment.  Hmmm.

ENGINE ENGINE we need to see the engine 

ENGINE ENGINE we need to see the engine 

A video of it running would be nice

Engine run

Radial Power! 7cyl Model Engine

Pictures

Nice....have you flown it in the AT-6?

Nice....have you flown it in the AT-6?

Yes I have flown it a few time but with the radial it's marginal on power hens the stearman project.
See my introduction post for a few pictures of the texan http://www.rcmf.co.uk/4um/index.php/topic,72001.msg797851.html#msg797851

I'm going to swap it out for a 100cc twin I have, not as pretty but has twice the hours power of the Seidel.

That's such a pretty engine which is justification NOT to go electric alone................ never seen a pretty electric motor 

Looking forward to your build thread 

Good advice Star Man, but having trouble finding part A at the moment.  Hmmm.

Did you get a map with this box of bits?

Got the plans today, 3 sheets full size one with both wings, one of the fus plan and profile, and one with all the parts layed out, but NO build instructions so I guess I'm on my own with this one, well me, myself and a few thousand of you on the web.  I'll take some pictures tonight of the box of bits to give you an idea of what you get for your money.

Construction manuals with plans are rare.......Jerry Bates does offer a handful with a few of his plans, but I don't think Ziroli does any at all for his (From personal experience of writing kit construction manuals, the time involved is high, so the costs would increase of they were included)

You'll get plenty of decent advise here, but it's worth having a look over on RCScalebuilder in the Ziroli section......there may be a few builds already on there, if not, someone who has built one........

RCSB - Ziroli Forum

Phil

Phil

I'm sure for most of you this is all as expected but I'm new to building and have never seen a plan before I thought it would be good to go through this build thread as a newbie and perhaps inspire others like myself to jump in, do one for them selves and stop thinking like me that this type of project is just for the balsa gods out there.  I'm laughing to my self in disbelief even as I type this post. Well its going to be a steep learning curve but I'm looking forward to the challenge.

OK got the plans, opened up all the part bags and all looks in good shape except for one piece that is bowed really quite badly, a quick call to Bellair and they are going to send me another pair cut from a new sheet. Thanks very much Leon.  OK off to my local model shop to purchase half a balsa forest for this build and start on my scrap balsa box another thing I don't have.

Excitement building here and watching with interest, have you built it yet. 

Excitement building here and watching with interest, have you built it yet. 

Well I found part A part B is not supplied in the kit, part C was bowed and found that cyano is not the preferred glue for this size of model so didn't get started last night. Perhaps you could confirm that "ALIPHATIC PVA" is required as I'm off to the model shop now?

I have to admit that I tend to use Cyano for a lot of my glue joints...the thick stuff seems best, applied to the area to be joined just like you would with wood glue.

Anything that takes slighty more load or I need the time to assemble the area in question then I would use Aliphatic wood glue. For wing joiners, bulkheads undercarriage areas etc I would use epoxy (slower curing being best here...ie 24hr.) Try Hysol from Fighteraces. Expensive but by far the best glue out there.

You will quickly learn just where to use what type of glue, but if you use a good quality cyano (ZAP is my favourite) and aliphatic then I can't see you'll have much trouble!

 

Steve

Should have said before...

Not wanting to take revenue from your local model shop, but if you are buying serious amounts of balsa then you will be FAR cheaper going direct to a balsa supplier. Balsa Cabin, inwoods, slec etc.

Steve

I use Cyano for 95% of my building on large models. All load bearing joints are done with various epoxies, 30 minute for smaller less critical jobs, 24hr for the major jobs (Loctite Hysol 9462). I use PVA very rarely, normally only for sheeting wings when I need time for applying large skins all in 1 go. I'm personally not a fan of the aliphatic glues........I don't think they penetrate well. If I do use PVA, it's a traditional white PVA (good quality wood working glue rather than a 'model shop' brand)

If you are finding CA is not bonding & penetrating the ply ribs & formers, this is normally due to the fact the parts are laser cut. Belair parts are MUCH better than most, but there is still a small degree of burning, especially on the birch ply parts......this has the effect of glazing the edge slightly making it hard for the CA to penetrate. If the edges are given a light sane to remove the burning, you'll progress much faster. Use a Permagrit spar slotting tool (they do a 3 and 6mm version) for sanding in notches and a disc sanded (if you don't have one, get one....they are invaluable) for all other exterior edges.

The brand & type of CA also makes a huge difference.......many will say use cheap & cheerful stuff from the likes of Screwfix as cyano is cyano, but the more expensive brands such as ZAP in my opinion are far superior. I've been through all the cheap stuff and will use nothing but ZAP these days. There is also thin, medium & thick...all are used for different jobs on different materials.

Thin for use on balsa to balsa joints where the parts are tight fitting and the glue is wicked into the joint after the parts are assembled (a longeron into a former for example)

Medium for balsa to balsa, or hard wood to hardwood joints where glue is applied to 1 piece and the 2 parts are pressed together. In some situations, a 'kicker' may be required to speed up the cure. This can also have the effect of creating a hard fillet around the joint where the excess has squished out.

Thick.....as above, but when a bit of positioning time is required, the thick cures a lot slower. Again, the use of a kicker is normal.

Also, don't worry about slightly warper ply componets.......it's a composite natural material and that's what it does!! Ply can be flattened if lightly heated over a boiling kettle and weighted overnight. Alternatively, as long as it's not putting excess stress on the assembly, most parts can be straightened during the built when other parts are glues to it.

Phil

Thanks for the advice Phil, I'm back from the model shop with Zap medium and thin cyano, MD aliphatic, Zap 5 and 30 min epoxy, plus a rather small looking amount of balsa and hard wood stock, a hole bunch of clamps, pins and a strait edge. I already have some permagrit tools from my last job and I pinched a sheet of clear acetate from work to lay over the plan, so nothing to stop me getting started tonight. 

Best you get crackin then 

Phil

Ok then day 1, 
  Pinned down the crutch parts (Not included in the kit) to the plan cut and sanded the cross braises, dry fit to the plan making sure every thing is as square and true to the plan as possible using the side ply sheets for possition as they do not exatly match up with the plan then glued with Aliphatic PVA. Once dry released from plan. I flipped the crutch over to check shape and found that the tail end was off by about 5mm from center of the plan not sure why this is perhaps the plans aren't perfectly strait? So pulled the crutch to the mean position while gluing the formers in place, notice on crutch2 pic that the diagonal braises are now opposite to the plans, I don't think this make any difference to the build? Then before the PVA has set, using runny syano on a couple of stringers ensuring the formers are square to the crutch sides.  The ply sides that were bent have now been straitened by holding the part concave side down over a pot of boiling water for 5-10 mins while stressing in the opposite direction.

The fire wall has a few degree of down thrust built in to the ply sides, I didn't notice this until I glued and clamped it all together. Not being a pro builder I am not making any modification to suit my engine at this point, assuming Ziroli knows what he is doing as I'm sure I don't.

I'm liking the Aliphatic PVA, it gives you plenty of time to move the parts in to position and has made a decent grip within half an hour, plus  and can someone confirm this I intend on using PVA to fill in joint gaps as necessary, plus pint for pint its a lot cheaper than epoxy and no mixing required.

I need to cut the stringer now this seems like a waist of 2 hours to me but I have the sheet balsa so I'll get on this job tonight.

Lots of good advice and help from Leon (BelAir) and RCMF keep it cumming.

Paul

Hi Paul,

Looking really good so far, I love this stage of any build as you can walk out of the workshop and know that you have seen progress 

I use aliphatic a lot but i wouldn't be wanting to try and make a bad joint good by using it as a filler, If you have a gap that needs taking up i would use some sliver's of balsa cynoed into the gap then filleted with aliphatic if required. Wood will add strength glue just adds weight and gives a false sense of how strong the joint is.

Just my 2p's worth

keep up the posting as this is looking like a very nice build 

Agree 100%........fill as many gaps as possible with wood rather than glue, you'll get a far stronger joint if the 2 mating surfaces are touching then wicked with glue rather than floating in mid air and using glue to fill the gaps.

Phil

Day 2, 8 hours of work so fare.
  I am really enjoying seeing it come to life in front of me and feeling quite pleased with the way it is going, however before I started gluing stringers in, I placed the fus crutch on 2 level boxes and noticed that the rear end has a twist in it, see pic "Before tweak" PANIC!  I fixed this with putting weights on the top deck to keep it flat and the with the aid of clamps twisted the rear end past the strait position and then glued the stringers with cyano so once all stingers are fixed it came back to the correct position, this was more luck than judgment but it has done the job see pic "After tweak".

The ply top decks are made from 2 pieces of light ply and glued into the formers with PVA this also ensures the ply sides are strait, then I fitted the 2 middle formers that are in 4 pieces, top sides and bottom, I think its worth saying at this point that only the formers and 4 ply sides are included in this kit, you have to supply & make your own stringers and ply top deck, I'm sure this is what is expected and is plainly obvious to pro builders but from a newbies point of view I am surprised, as I am used to finding all required parts in the box when making ARTF and so on.

I have attached a few pictures of work done so fare, I will need to have a good look at the plans before doing much more as the wing supports and undercarriage need to penetrate the outer skin and fix to the ply box, so I will need to confirm position before skinning, if I have not already covered the positions with stringers? Re the stingers I needed to widen/move some of the stringer slots in the formers to achieve strait lines is this normal?

One question the stringers I have cut aren't all long enough to reach the entire length of the fus due to the stock availability at my model shop (See fus nose pic), is it OK to join them and how should this be done, just glue tip to tip or should I braise them in some way?

Paul

One more question for you pros.  After I have finished the stringers and sanded to shape I will need to think about skinning, the plans specify 2.5mm to 3mm balsa sheet. I don't know were to start, have no idea how sheeting is done, what glue to use, how to clamp it down etc. etc. Can anyone help with some tips?

Paul

Ref joining stringers........... use a scarf joint at about 6-1 angle nice and long 

Coming along very nice and you say you have not done any building before?  If that's the case then this is very impressive 

Ref joining stringers........... use a scarf joint at about 6-1 angle nice and long  

Coming along very nice and you say you have not done any building before?  If that's the case then this is very impressive  

Yes this is my first build from a plan, I have built a couple of fiberglass models from FULL KITS and one had a foam wing so some work was required but nothing of this magnitude.

 SORRY WHAT IS A SCARF JOINT? do you mean slice both parts at an angle?

Paul

yes, see here...

http://en.wikipedia.org/wiki/Scarf_joint

Lifted from google too.

For the greatest strength, make the scarf length 8 times longer than the width of the timber. Measure the timbers and mark the scarf positions on each. The splayed faces must be measured, cut and planed accurately to perfect the bond. The faces must butt exactly together.

I like scarf joints, once set, you can normally bend the longeron and it will break on an un-joined bit, not the joined bit!

I like scarf joints, once set, you can normally bend the longeron and it will break on an un-joined bit, not the joined bit!

And within reason have the same flexibility.  I have seen many builds on here that are fantastic yet the outer skin often 1/8" balsa are either but joined or with a slight scarf giving a perfect fracture point.  Not an issue is the structure under is strong enough in it's own right but no good if the skin is part of the structure rather than to make the shape up.  I doubt anyone would do it but the perfect scarf would not only be 6 (or more) to 1 throughout the length but also in thickness.

I doubt anyone would do it but the perfect scarf would not only be 6 (or more) to 1 throughout the length but also in thickness.

Good game, good game 

A 6 - 1 scarf on a stringer or longeron is perfect. When scarfing sheeting, I generally scarf at 45 degrees...................like so..............

Sheeting a model of this size really depends on what thickness timber is being used, and the radius it has to conform to.

I'd recommend you use 1/8" sheeting.......this is relatively thick for a model this size, but gives plenty of sanding thickness to end up with a 2 - 2.5mm skin

For tight radii, you can either 'plank' the structure or sheet it in larger section with the help of 'ammonia'.

Planking is basically gluing planks of balsa around 8-10mm wide edge to edge around the structure. It's time consuming and quite fiddly as each plank has to be cut with it's edges slightly chamfered to ensure it butts up to the last plank with no gaps. Also, as a fuz is likely to be tapered nose to tail, some planks will also be tapered along their length.

I prefer the sheeting option using wider sheets as it's much faster & I feel gives a better result as there are fewer joins (but joints between sheets are best done directly over a longeron or stringer as this gives something for each edge to bond to). If the timber is not flexible enough to conform around the structure with 'light' pressure, you can apply ammonia to each side of the wood with a sponge, let it soak for a few minutes and the balsa becomes VERY flexible along it's grain. The wood can be wrapped around the structure and taped in place until dry....once dry, it's cut to side and bonded on with cyano. (Planking however is normally done with PVA - Aliphatic as it's easier to sand the excess that squeezes from the joints).

This is what can be done to medium grade 1/8" balsa with ammonia...............this section of the tail of a Sea Fury was sheeted in 1 piece.

Phil

Its probably what Phil did here, (the photo's may suggest otherwise) but it would be a lot easier to shape the section over the tail (above) from an over size sheet before any of the surounding sheeting was added and then trim to size and fit later.

.....yes, that is what I did.......but the photos were taken after not during the process!!

Phil

Day 3 - 13 hours so fare.

I cut a bunch more stringers, getting quite handy at this now.  Spent about an hour scratch my head looking for a part that I don't have, one of the rear lower formers "F9" and wondering why I have two front lower formers "F2B" spoke to Bell Air and I should have it as both the missing one and the extra formers are on the cut sheet, Leon will cut me a new one today and get it to me for this weekend, fingers crossed - What a nice chap.

Because of this delay I didn't get much done, some ply sides and lower deck to the box section, notice the lower deck angle needs to be correct to allow the 2 remaining formers to sit at the correct depth so I dry fitted the leg mount formers when gluing the bottom deck in place (Bottom deck not included in kit), I couldn't finish off the stringers as the last former is missing, the parts I made and fitted went together with no dramas see pictures for detail.

Thanks for your reply Phil, ammonia! isn't that quite a nasty chemical, are there any special precautions required?

How do you know that, what every made someone think of using ammonia in the first place.  These forums are a really useful and necessary resource for novices like myself, thank you.

Paul