Bistormer 60" (A Barnstormer with more ribs)

[Nigel Day]

'Slapping epoxy everywhere'.

Won't do much for the weight will it?

[Nigel Day]

Please forgive me Danny but I'm new to this type of modelling.

Accuracy issues aside, what's the practical effect of the .5 degree angle difference to the construction?

Btw, the notes and images are very useful, many thanks. I'll be doing my wings some time in March I think.

Edited By Nigel Day on 23/01/2014 08:53:25

[Danny Fenton]

Thanks Cymaz I am not sure SWMBO will let me near her whiskey even on medicinal grounds

LOL Tony I know once you let the standards slip, you may as well go whole hog!

Hi Nigel, the build becomes more difficult if bits don't fit properly. If the designer intended there to be 4 degrees of dihedral then he will have designed the cabanes and all the wing mounting geometry for this. I agree a 1 degree difference does not appear much but I do like to get things spot on and its annoying when you have cut your parts very accurately to supplied templates only to find they do not follow the drawing accurately. I have had to take a mm off the underside of the dihedral braces which obviously weakens them ever so slightly.

I was joking when I said slopping epoxy everywhere, bit of an in joke as Tony alluded to, I am very fussy usually though this model is pushing my OCD to the limit

I will do the bottom wing in the sequence I think they should be done and you can then see which you prefer Nigel, are you doing the 60" version?

Cheers

Danny

[cymaz]

Danny its a good job you don't have my 72" bistormer. Flies sooo beautifully on an OS91 BUT on the lower wing one half is 1 inch longer than the other.

Happy days

[Danny Fenton]

ARGHHHHHHHHH!!!!!!!! must go lie down......

[Nigel Day]

Thanks Danny. I WAS joking about the epoxy. Seeing your build so far I can see you're very meticulous.

As a newbie I'm trying to get a better feel for what errors and discrepancies make a material difference to the strength and appearance as opposed to simply offending the builder's sense of perfection.

Most of the time I also want to get it exactly right but it's useful to know when 'good enough' is enough in cases where adjusting or redoing something either isn't an option or would be a real pain.

Yes, I'm about to start the 63" B'stormer. I'm currently poring over the plans and the blogs from Tony, Phil and Jeff to see what mods, if any, I want/need to make. I'll be going electric.

It's the placement and fitting of trays and hatches which is making me think the most. Without the experience that you guys have I can't easily visualise where openings & fittings are needed, when to build them, and what mods to make to the basic plans.

This is all good stuff and one of the things that looks as though it'll make building even more interesting and fun.

Edited By Nigel Day on 23/01/2014 10:24:11

[kc]

I have always found that David Boddington's hand drawn plans are accurate and informative. Much better than many CAD plans.
Is it possible that the main drawing is by Boddo yet the template has been done later by someone else? ( there have been several succesive owners since Boddo)

Nigel. Regardless of who drew the plan I always go over the plan comparing former widths etc with fuselage side & plan view. Dividers or plastic vernier calipers or just a ruler will quickly reveal any errors and studying the plan before cutting wood will save time & material.

Edited By kc on 23/01/2014 11:28:49

[Biggles' Elder Brother - Moderator]

Nice work Danny - coming along well and looking good.

This is a great blog BTW - just the sort of detail new builders need and its providing great insights into building techniques.

Picking up on Nigel's point: new builders shouldn't be discouraged in any way by any "issues" being flagged up - there will always be challenging areas in any build. The real point is that with the Mass Build approach you get a "roadmap" provided by a more experienced builder of how to cope with those little problemettes. And that is exactly what Danny is providing here.

You ask a really difficult question when you say "how do you know when an issue is problem and has to be addressed and when it will be good enough and can be left". I suppose in the end that one comes down to experience. And this is one reason why we encourage new builders to do blogs - not just experienced builders. That way you can ask questions about your build - you can ask "Is this OK or do I need to change something?" or even "help, how do I fix this"!

I think one of the things that really characterises an experienced builder is the way he may be doing X, but actually at the same time he's really thinking about Y that he won't be doing until next week. He's constantly asking himself the question "What will be the knock consequences of what I am doing now?" and he's thinking out problems on future aspects of the build all he time. Notice Danny says at one point something like "I was thinking about how I was going to do the cabanes". He's not doing them now - but he's thinking about how what he is doing now will impact on that stage later. I know that when I'm "in a build" I'm constantly (and I mean constantly - often when not even in the workshop!) thinking about "how am I going to do this or that" and "this or that" is often well in the future.

For example, take the question "does 1 degree error in the dihedral brace matter?". Well in terms of it being a dihedral brace, no not at all. In term of the job in hand - joining the wings - it matters very little (Danny's OCD apart ). But an experienced builder isn't thinking about those things - he knows he can sort that. What he's thinking about is that a 1 degree difference here, at the wing root, will mean that out there, at the wing tip 30" away, he'll be a whopping 12mm out of position! Now suppose the inter-wing struts are on the plan at 300mm long - the gap they go into will now be 312mm. This isn't going to work! (I don't know if the Bistormer has inter-wing struts - but you see my point).

OK, this can be fixed - but it shows how a very small error in one part has bigger consequences further down the line.

The thing to remember though is that, in my experience, there are very few of these challenges that can't be fixed, worked around, or modifications implemented to cope with. The difference between a new builder and Danny is; Danny already knows he has an issue in the future because of what he is having to do now. A new builder would probably just carry on, unaware, then eventually some time later make the strut to plan size and then look puzzled when it was half an inch too short! He'd then make another one longer - and make a mental note not to fall for that one again. And being an "experienced" builder is in reality for most of us the painful process of many years of making such "mental notes not to do that again"!

BEB

[Danny Fenton]

Hi Nigel, I am more than happy to help any way I can re hatches etc and mods for electric. I am torn between doing the fus next or the other wing. My head is still mulling over what to do with the fus, as I am going electric too, the entire front end is over engineered. and to make matters worse the structure utilises "rails" as you have no doubt seen. This doesn't translate well to bulkhead mounted leccy motors.

Also the ply fuselage doublers are there to transfer massive vibrational loads that are simply not present with electric so could be modified to save some weight. With regards to weight, I am not trying to save weight because its electric, I am trying to save weight because of the flying characteristics that I want from this model. I really enjoy flying a Cirrus Moth that I renovated for my friend Chris, and I would like this to float around with the moth. The wing section is not really right for the role, however if I keep it light I may be able to slow it up enough we will see.

I noticed BEB answered your thrust line and motor moving question in his DF thread. All valid points, however I may be moving the motor down on mine. You may already have noticed if you have been studying the plans that the leccy motor mount would have to be higher than the available bulkhead on the BiStormer, so mods have to be done. Either the motor gets lowered or the bulkhead raised I am still musing that one.

I also do not like massive down and side thrust, I think it looks awful on a model and am happy to play with the rudder and elevator to compensate for power settings. After all that is what you do on the full size.

BEB I really must thank you for such a clear and concise post, you even make me sound like I know what I am doing, the choccy biscuits will be in the post

You have, as always hit the nail on the head, and put it so eloquently. I guess we do always keep in our minds, what impact will this decision have later on. There are no struts on the Bi Stormer, though i am still really struggling to decide whether to build this vanilla or to try and make it look period in a semi scale kind of way. Which would then mean struts.

Re the dihedral, I cadded the head on views and worked out the amount the dihedral would change at the tips if it was only 3 degrees, and it would have meant 1.835 inches under one tip with the other flat on the board.

My brain is churning modelling stuff like this over ALL the time, good job driving is second nature. My wife wonders how I can drive for hours without any form of entertainment music/radio etc. Well now you know

KC I think you are right the drawing does seem accurate, its the sticky printed templates that are out.

I will be more vigilant and compare my parts to the plan from now on!

Thanks for all your feedback and comments, it does make doing these blogs all the more rewarding.

Cheers

Danny

[kc]

Recently I have electrified a couple of models intended for glow. In each case I decided it was better to move the engine bulkhead forward so the Lipo came as far forward as possible to help make CG position without lead.
To me putting the bulkhead forward is much better than using standoff type mounting. What are your thoughts Danny?

[Danny Fenton]

Hi KC, I agree. The first few conversions I did were using threaded rod as standoffs. Worked fine but was a waste of valuable real estate under the cowl. A bulkhead further forward is a much better solution

The BiStormer may be odd in that I am probably going to use A123, with these there is no need for a hatch as they can be charged in the model. We will see how I feel when I get closer.

Of interest I converted a pupeteer a few years ago and was able to shorten the nose by nearly 2 inches because the motor and battery could be positioned much further forward than an ic. Thoughts of the C of G is always tugging at the neurons we do not like lead!

Cheers

Danny

[kc]

As the nose normally narrows in, moving the bulkhead forward means a change of width and height of the bulkhead. I simply mark the new position on the plan and measure height & width at that point, then make the former a similar shape but to the new dimensions. I am sure that Danny will know this method but it may not be obvious to newcomers.

[kc]

I suppose the bulkhead position has to be determined after the motor is selected. DB suggest a 4 Max motor and they suggest their PPO 5055 which is 1580 watts and has an 8mm shaft. Seems massive to me -- again whats your ideas Danny?

[Nigel Day]

Thanks kc.

That's just what I've done. So far the dimensions on the plan match the inside of the lines drawn on the patterns/templates - but then I've only measured less than 1/4.

[Nigel Day]

Nicely explained BEB.

As you say, these blogs are a great source of ideas and information for a newbie when doing the model. I've learnt a lot from following the (at least) 5 different Barnstormer builds going on currently.

I'm currently reading three of them and am starting to understand the decisions and rationales of the various builders for the decisions they've made. I suspect that I'll 'pick and mix' from them when I build and 'wing it (sorry)' a little too. All part of the learning experience.

[Nigel Day]

Thanks Danny. I don't think that Phil changed the position of the bulkhead (F2?) but I have a feeling that he increased the height of it. That might have been for the top hatch though.....

I'll make sure to check my dihedral templates. The others that I've checked seem OK but you've made me a bit more wary of relying on them all.

Many thanks for the info and guidance so far.

[Danny Fenton]

Hi chaps, thanks for all the comments its great to hear everybody chipping in.

KC George likes the 5055 and 5065 motors so do I. They come in loads of different windings (KV) so you can tune the prop cell count etc to the power that you want. However in this instance I want this aeroplane to stooge about so 100 watts to the lb rule will be adequate I reckon. The motor I have gone for is an old one I had lying around, it is around 500kv and will work nicely on 6 cells A123 (5 cells lipo) and turn a 14 x 7 ncely. It should deliver draw around 6-700 watts of power. It wont be as efficient as some of the newer motors, but in this application it will be fine. Georges motor (4Max) will be good for a model of 15lbs. I don't know how heavy this one I am doing will come out but I would be a bit dissapointed to be far over 6 lbs.

Redesigning front ends. This is something I usually do right at the beginning of the build, but haven't in this instance. I have this nagging feeling in the back of my mind to stick a Laser in it. I have never had nor operated a Laser but I should. Anyway I am sure the feelings will pass, bit like the flu

This is a drawing I did for a Brian Taylor Hurricane:

If you look closely you can see the motor and a new box structure that lies inside the original bulkhead but extends forward. This is a way around making a new bulkhead of the correct shape, just extend a box forwards.

These are drawings using a similar approach I did for the TN Spitfire:

both of these are using the 5065 Turnigy motor, swinging a 20 x 13 three blade prop.

Nigel I think you are absolutely spot on, take the ideas you see and try a few, some you will like some you may not. Pick n mix modelling

Theres no right or wrong way

Cheers

Danny

[Danny Fenton]

Right a couple of snippets to show you, nothing exciting and you older hands can go back to sleep, nothing of interest, move along......

The glue I use for slower jobs is Titebond, I seem to alternate between Titebond original and titebond II I find the latter dries a bit quicker but other than there isn't much in it, well not to me anyway.

Titebond seems to come with a silly nozzle so I usually decant it into this smaller bottle with a long tip for ribs and small areas etc

But for sections like wing leading edges I use the normal huge nozzle, lather it on then using the Palette knife scrape it off again, this leaves a nice film ready for the wood. Seems wasteful perhaps, but in the grand scheme of things its not much.

You will also notice the pins I am using, there has been a bit of chatter on the forum regards pins and the glass headed ones shattering causing an impaled thumb. Well I present to you these nifty pins. They are available from lots of good model shops, and if you really shop around you can be trendy "like what I is" and go for pink You will notice these are all the rage on the US forums. I got mine from Al's.

Here are said pins in action holding the upper centre section sheeting still. Had a bit of a mishap with regards the sheeting. This model is eating 1/16 sheeting like the proverbial! Anyway I try and always use stock from the same supplier. The reason is one outfits 1/16 is another outfits 1/16 less a bit. It is almost as if they are passing metric 1.5mm as 1.6 but with 1.5 the sheet should be 1 metre, the 1.6 it should be 36" So anyway I mixed the wood as I ran out of the stock from SLEC and dove into a pile I got from elsewhere Just means you may have to sand the area where the two meet a little to bring them level.

Next up, if you wanted to cut a sheet of 1/4 perpendicular to the grain, who would reach for a knife? Not saying that is wrong, but you may find this method easier and a lot less fuss. Mark the length and lay your set square across the wood. Gently rest the saw against the square and cut. You will get a lovely neat and accurate cut. TIP Never use your best saws on anything but balsa, and for ply use the cheaper saws as the resin in them seems to chew blades.

Next up we attached the leading edges. You may recall instead of using 1/2 balsa I used laminated 1/4 This worked very well. But first of all how do we hold the wing to work on the beast?

These blocks of foam have wedges cut out and will hold almost any wing so you can work on the leading edges. Cheap to make too,

I use good quality tape that neither leaves a residue but has good grab. This blue tape from 3M is not cheap but I wont use anything else. It is also an excellent tape for masking.

Anyway hope I haven't put everybody to sleep, not necessarily the only way to do stuff but it is how I do it. Now where is my Lemsip.......

Cheers

Danny

Edited By Danny Fenton on 23/01/2014 23:14:55

[Concorde Speedbird]

6 pounds is very light for a biplane of this size, my 45" span Domino aerobatic biplane is 6 pounds, so I wouldn't be worried if it goes above 6 or 7 pounds. Keep up the good work.

CS

[Danny Fenton]

Thanks CS, I am choosing the wood, and that I am hoping will make the difference. I think the Domino also has foam wings? It all adds up. But you are right it is a big model to keep under 6lbs. We shall see

Perhaps we should start a sweep, see who can get closest to the final weight?

Cheers

Danny

[john stones 1 - Moderator]

lovely building Danny.

like your use of highlighter pens and foam to hold wings

great tips

[Barrie Dav 2]

That's a beautiful bit of building there Danny. Why does a well built balsa model look so good?  Well, it is an art after all......

Has anyone had issues with using cyno for the main glue when building? I've always understood that it becomes brittle with time and the joints can come apart if subjected to a sharp knock (usual in my landings).

Edited By Barrie Dav 2 on 24/01/2014 08:21:46

[Danny Fenton]

Thanks John and Barrie, and thanks for joining in. It makes it more interesting to get feedback.

I have not had experience of CA weakening over time, but would be interested to hear more?

Anybody else heard about this?

Cheers

Danny

[Colin Leighfield]

I've not heard about time-related deterioration, but I'm aware that brittleness can be an issue, which perhaps makes joints more prone to shattering in an impact where an epoxy joint would hold together.

Perhaps it's one of those variable things related to the type of cyano glue being used? I have the impression that joints made using thin cyano "whicked in" aren't as robust as those using a medium cyano, but perhaps that's simply due to the volume of adhesive and effective surface area of the glued faces.

Like most people I suppose, I use thin and gap-filling cyano, epoxy, PVA, contact adhesive and balsa cement is still surprisingly useful. My Tucano wing panels are wholly glued together with Uhu Hart without the slightest problem, epoxy being used just for the centre join.

However, for a quick build with ribs in a built up wing panel or dropping intermediate formers into a balsa sheet fuselage, I use thin cyano all the time. The loads on those joints are well distributed and if there is an impact severe enough to shatter the joints, I doubt if there's enough left of the plane to be worth worrying about anyway!

[Barrie Dav 2]

I generally use Aliphatic glue and sometimes, where it's too difficult to use a metal pin, use a spot of cyno on a very small section of bare wood to 'pin' the former/rib etc. in place whilst the wood glue sets. I've done this for years and it speeds to building no-end. Thus the wood glue takes all the knocks.