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Bistormer 60" (A Barnstormer with more ribs)

Barnstormer with more ribs

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Danny Fenton03/01/2014 12:32:48
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8986 forum posts
3871 photos

Well I will be soon start cutting wood for one of these. This one will be electric for a 6 cell A123 battery pack. I will endeavour to make it look a little more like a 60's home built aerobatic bipe if possible, but the inline engine cowl may make it interesting as most homebuilts of that period utilised flat four cylinder configurations.

I think there are many similarities between the Bistormer and the Barnstormer and the construction techniques that Barnstormer builders are detailing should suffice so I think it will be okay to divert from plans a little.

First off I will have to alter the drawings to suit the motor I will be using, as the bulkhead distance needs to be set.

Cheers

Danny

Nigel Day06/01/2014 14:43:54
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1158 forum posts
213 photos

I'll be looking over your shoulder with the obligatory coffee and (chocolate) digestives to hand.

Concorde Speedbird06/01/2014 15:23:30
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2713 forum posts
628 photos

Excellent, I like Biplanes a lot, for short landing approaches they are great fun, side slip them and you can have a lovely steep approach.

CS

Danny Fenton19/01/2014 00:03:08
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8986 forum posts
3871 photos

Hi Chaps well enthusiasm on the Apache has kept me away from starting this but finally got an hour tonight after little Roisin went to bed.

I would first of all like to ask if anybody else is building one of these? Secondly and if you want more information to just holler out!

Thirdly there are errors in the written instructions, which means the plan and instructions leave you in a state of uncertainty. Alright for me cos I will just blunder along and fix whatever goes wrong but might be frustrating for somebody with less airframes under their belt.

Firstly the wing joiners were made. The nomenclature or labelling on the plan matches the cutting sticky back sheet, however the instructions have the upper and lower ply joiners the wrong way around. The long ones go on the bottom wing, with the added centre section.

The basic idea is that the trailing edge 1/16 is laid down on the plan. (protected with Balsa Cabin Plan protector polythene sheet). As well as the two lower spars and all the ribs. The spars are packed up off the plan by the thicknes of A. the forward sheeting and B. by the capping strip thickness. these are 1/16, so the scrap pieces of packing are 1/16 balsa.

The forward upper and lower spars are cut from 1/4 balsa, speciafically chosen that is heavier at one end than the other. This often happens and its not usually hard to find a piece like this when sifting through stock at the shows. The heavy/harder goes towards the root. All the spars are cut from this stock, so are consistent.

The lower rear spar is another area for confusion. On the cutting list, it is shown as 3/8 x 1/4 but the slot laser cut into the ribs, and mentioned in the build notes is 3/8 x 3/16 anyway the laser cut ribs are a given so the spar must match. Again I cut these using a SLEC stripper. Talking of this tool its at least 10 years old and still has it original blade. Usually cuts first pass too wink 2

I set the ribs onto the forward spars, but leave the rear spar floating, The ribs are all the same and the rear spar ends up a fraction out from the plan. This doesn't matter. Once all the ribs are dry fitted in place the spar will allign itself.

The leading edge is made up of massive chunks of 1/2 thick x 1" logs! I don't like that so will be using two laminations of 1/4" The end result will be the same.

Hopefully the pics will match the lyrics party

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Cheers

Danny

Tony Bennett19/01/2014 00:23:48
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5050 forum posts
129 photos

looking good so far young man.

Danny Fenton20/01/2014 00:20:32
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8986 forum posts
3871 photos

Thanks Tony, its going to be slow going as I am not getting time at the bench. Just come upstairs at 11:40 and have managed to cut and fit the trailing edges. But that's it for tonight. Never mind you have to eat an elephant slowly or so they say.....

bs 8.jpg

Before the ribs could be secured, the root rib angle has to be set using a simple balsa jig. This is to allow for the dihedral when joinging the two panels.

bs 9.jpg

Not the only way to do this, and indeed if you look at BEB's recent Dawn Flyer build blog you will see he does it differently to me. I like to sand the top sheeting with a chamfer to fit the rib and lower sheeting angle. Each to their own wink 2

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Her is the fit of the trailing edge sheets.

bs 11.jpg

And as close to multi tasking as you will find me, two wing panels at once.

This model will be virtually stock, and only have ailerons on the lower wings.

Cheers

Danny

Tony Bennett20/01/2014 08:07:02
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5050 forum posts
129 photos

still it is a good start Danny.

slow and sure wins the race.

Nigel Day20/01/2014 15:56:43
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1158 forum posts
213 photos

Some good tips there Danny, cheers.

kc20/01/2014 18:56:06
5820 forum posts
167 photos
I am not building this model but the pictures are very enticing....maybe I will change my mind!

Danny, you said " I set the ribs onto the forward spars, but leave the rear spar floating " perhaps you could clarify this for any newcomers building this or similar wings. I take this to mean you pinned down the front spar to the board ( with spacers) along the marked position but left the rear spar unpinned to find its own position fore & aft as dictated by the slots in the ribs. Then you pinned the rear spar down to the board ( with spacers) Is that correct?

I think others would be interested to know whether you cyano each rib in position so the glue dries before the next rib is fitted or whether you glue them all in with PVA and let all the ribs dry together overnight.
Danny Fenton20/01/2014 19:37:30
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8986 forum posts
3871 photos
Hi KC I am glad you are enjoying following along. You are spot on with your description (clearly better than mine ) as for the ribs, I set each one vertical and use thin CA wicked into the joint. I let it dry before moving on to the next. I am very impatient lol I use Titebond II for the areas that require more time to position.
Thanks for pointing out my lack of clarity, thats the trouble with posting late at night
Cheers
Danny
kc20/01/2014 22:48:39
5820 forum posts
167 photos
Thanks Danny. Actually I do my wings the same way with cyano.
Colin Leighfield20/01/2014 23:02:56
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5715 forum posts
2359 photos

I'm torn by this, because if I had a chance to do a second project for the mass build it would be this one. I'm interested to see how long it takes you Danny. I've got to finish off existing priorities first, so it would need to be a fairly quick build.

Danny Fenton20/01/2014 23:20:36
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8986 forum posts
3871 photos

That's good to know KC. I am using a lot more medium these days, especially where ply is concerned seems to give a better bond.

Hi Colin, I am not sure how quick it will be, I am hoping that it won't be too long, I seemed to spend all evening tonight trying to work out what the instructions are supposed to be telling me. TBH I wish I had screwed them up and done things my way. Sorry Eddie but I think the instructions may need amending in places..... eg do the wing retaining before sheeting the top leading edge GRRRRRR!!! wish I had seen that one coming.

Anyway not much to show for a good 2 hour stint crying 2

bs 12.jpg

Leading edge was fitted, and planed flush with the ribs. This is not how DB recomend, but I prefer to sheet over either a false leading edge, then add a real leading edge. It increases the gluing area for the leading edge sheeting and makes for a stronger D box section in my opinion. The leading edge upper sheeting is added as per the DB instruction sheet sad

bs 13.jpg

Looking through all the Barnstormer builds I haven't seen anybody show how the wing (in my case upper) is attached. On the Bistormer there are two ply plates per panel and these are fitted flush with the lower edge of the ribs. This may not seem strong but by the time the lower sheeting is added it will be plenty strong enough. Just to make sure at the front hardwood rails are fitted.

bs 14.jpg

And at the rear, though not required by the plan, I have added some 1/4 sq section to add a little support.

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To transfer the position of the holes from the plan to these ply plates, first the bit of the plan was traced and the two crosses transferred to the ply.

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The play plates are supposed to have 4BA nuts epoxied to the underside, I am opting for a slightly more modern (though not by much) and am fitting 3mm blind nuts. The 1/8 ply plates wont handle the depth of these so additional plates were made up from ply and the blind nuts nipped up tight.

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Voila!

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I usually cut play washers to go over the top, but in this instance I am going to simply epoxy these in place. The epoxy resin has been mixed with coloidal silica to stiffen it.

All that remains is to fit these small plates inside the wing behind the FITTED ply plates, would have been so much easier before the sheeting!!!

I am full of flu I am afraid, so had to call it quits for tonight, me and a lemsip are off to bed face 21

Cheers

Danny

Colin Leighfield20/01/2014 23:37:06
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5715 forum posts
2359 photos

Thanks Danny, I'll keep watching.

Tony Bennett21/01/2014 09:01:08
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5050 forum posts
129 photos

looking nice so far.

i never even looked at the build instructions on the barnstormer (did it come with any?)

Danny Fenton21/01/2014 09:10:54
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8986 forum posts
3871 photos

Hi Tony, probably wise my friend wink 2 They came with the plan and ribs from DB. I thought it would save time stewing over bits, but in actual fact it has slowed me down.

I am correcting them as I go so will stick at it.

How is the wing mounted on the Barnstormer Tony?

Cheers

Danny

Tony Bennett21/01/2014 09:46:52
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5050 forum posts
129 photos

same way as you have done yours.

though i built the wing and positioned the fuse with cabanes onto the wing to line it all up, then marked and fittet the mounts.

kc21/01/2014 12:31:37
5820 forum posts
167 photos
Danny could you explain a bit more about the photo of the T nuts being fitted - I assume it shows an allen key being used with a bolt to draw the T nut prongs into the ply and the collet or collar and thick ply are just used as spacers or washers. Have I viewed it correctly?

I have to say that whenever I have fitted T nuts this way they always loosened eventually so I now coat them with epoxy before drawing them into the ply with a greased bolt. Messy but it lasts longer!

Edited By kc on 21/01/2014 12:33:18

Danny Fenton21/01/2014 13:56:14
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8986 forum posts
3871 photos

Hi Tony, as I drank my Lemsip last night I was musing about the alignment. I think I am going to have to fit the cabane struts to the wing and adjust the fit on the fus to get everything straight. The instructions are actually making the build harder smile o

Hi KC, the nuts are glued as they are pulled into the play as well as coated on top. The procedure is as you describe. I usually use a small ply disk with a recess to keep them in place but this will suffice.

merlyn 2.jpg

merlyn 3.jpg

Cheers

Danny

Danny Fenton22/01/2014 17:53:50
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8986 forum posts
3871 photos

Well I am persevering with the instructions, but I wont be following them for the lower wing. The sequence doesn't suit my building style at all crook

Added the lower leading edge sheeting, the capping strips to the tops and bottoms of the ribs, and the wing tips.

bs 20.jpg

Also completed the spar webbing. I would have done the webbing before any sheeting but my OCD says I must following instructions sad

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I have included this shot to give some scale, its not as small a model as it first appears, it has a good sized chord.

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I then cut the slots for the plywood dihedral braces and epoxied them in place, being very careful to align the lower surface with the spars.

bs 24.jpg

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I know there has been chatter on the forums about epoxy stirers, and lots of people use coffee stirers, well I really find a palette knife gives really superb control, and lets you get epoxy where you want with precision. A quick wipe with acetone and its clean.

Cheers

Danny

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