2013 Mass Build - general chat thread

[Nigel Hawes]

David -

1/8 of an inch span loss is so negligible that you shouldn't worry.

As for cutting the ailerons out before profiling, I'm not sure how you would get round that! I wasn't consulted on the CNC woodpack, nor have I seen one, so I can't really comment.

Normally I'd advise you to spot glue the ailerons back in and then release them after profiling but if their outline has been CNC routed, then this won't be possible due to the routing gap.

I imagine whoever designed the cut left them attached so they could be profiled BEFORE releasing, but if only small tabs have been left, then they'd probably break out anyway as the profiling stage involves quite rigorous planing and sanding.

As a last resort you could make some new ailerons from some spare 10mm soft balsa sheet which are a very tight fit in their apertures, then as above, spot glue them in, profile the wing and release them at the end, shaving 1mm off each end for operating clearance.

I'm sure over the course of this mass build some better solutions will be posted!

[Phil Winks]

David regarding profiling the ailerons now they're seperated how about using some good decoraters masking tape, wide stuff, underneath the wing to hold them in place while profiling this is usually done with the edge of the wing laid close to the edge of the bench and the wing flat on the bench so the tape underneath should keep the ailerons in place during the operation.

Phil

[Delta Foxtrot]

Posted by Nigel Hawes on 01/12/2012 06:30:26:

David -

1/8 of an inch span loss is so negligible that you shouldn't worry.

As for cutting the ailerons out before profiling, I'm not sure how you would get round that! I wasn't consulted on the CNC woodpack, nor have I seen one, so I can't really comment.

Normally I'd advise you to spot glue the ailerons back in and then release them after profiling but if their outline has been CNC routed, then this won't be possible due to the routing gap.

I imagine whoever designed the cut left them attached so they could be profiled BEFORE releasing, but if only small tabs have been left, then they'd probably break out anyway as the profiling stage involves quite rigorous planing and sanding.

As a last resort you could make some new ailerons from some spare 10mm soft balsa sheet which are a very tight fit in their apertures, then as above, spot glue them in, profile the wing and release them at the end, shaving 1mm off each end for operating clearance.

I'm sure over the course of this mass build some better solutions will be posted!

Nigel,

Thanks for your comments, it is good to get advice from the designer.

I agree that the loss in span (1/4'' as both wings are 1/8'' short) is no big deal, but is annoying that laser cut parts should have such errors.

I looked at more parts today and noticed some more minor problems. The dihedral braces are so badly cut they are scrap. The fuselage sides replicate an error on the plan, in that the top line is too high behind the cockpit, it would be good to confirm that the plan does have an error there. There is also no triangular stock in the woodpack. These are easily rectifiable and will hopefully be fixed for later copies.

Thanks for the advice on the ailerons. I thought about tacking them back in with thin sheet to shim them into position and to support the ends. If this fails I will cut new parts and proceed as your build article. I think that the CNC parts should be modified to remove the aileron cuts for future copies.

Thanks

David

[Delta Foxtrot]

Posted by Phil Winks on 01/12/2012 17:35:33:

David regarding profiling the ailerons now they're seperated how about using some good decoraters masking tape, wide stuff, underneath the wing to hold them in place while profiling this is usually done with the edge of the wing laid close to the edge of the bench and the wing flat on the bench so the tape underneath should keep the ailerons in place during the operation.

Phil

Thanks for the tip Phil, I will certainly try this.

David

[Phil Winks]

Posted by david fillingham 1 on 01/12/2012 18:16:04:

I looked at more parts today and noticed some more minor problems. The dihedral braces are so badly cut they are scrap. The fuselage sides replicate an error on the plan, in that the top line is too high behind the cockpit, it would be good to confirm that the plan does have an error there. There is also no triangular stock in the woodpack. These are easily rectifiable and will hopefully be fixed for later copies.

Some concerning issues you've highlighted David and that makes me think twice about ordering the wood pack despite the discount. plus a complete or at least comprehensive cnc pack kinda turns a plan build into a kit build !

Also There are a few scaleing errors on the plan probably acumlative errors that appeared as a result of transfering from Nigels files to another cad prog for instance the wing chord at the root is different (By 4mm) on the wing plan to the side elevation of the fuselage. Yes I've taken in to account the taper

Phil

[Colin Hooper]

David

I also have the wood pack and my first check was that the fuselage sides did not repeat the error on the original plan. The sides are correct, it is the plan which is wrong. The sides need to be higher behind the cockpit to allow for the triangular stock (not included!!) to be positioned on the inside edge. This gives the turtle deck someting to glue to.

I have not looked at the other components in detail but I was pleased to see the motor mount (F1) is much thicker than the original plan and will, therefore, have more glueing area and less risk of delamination.

Colin

[Nigel Hawes]

Sorry Colin,  I'm afraid that is incorrect.

There IS an error on the plan, which at the time crept in when my hand-drawn plan was converted to CAD. As my drawing had no little triangles showing the fuselage side extents, the RCME draughtsman assumed the upper edge, an easy mistake to make.

The triangle stock DOES NOT go on the inside edge of the upper fuselage sides! Nor is it conventional triangle stock: it is flat-edged triangle stock, the flat edge being 4.5mm across, to match the thickness of the fuz side stock. This goes on top of the upper edges of the fuselage side and provides a platform for the thick 10mm upper decking, and a generous fillet for rounding the upper deck and empennage correctly without losing strength.

Edited By Nigel Hawes on 01/12/2012 19:19:04

[WolstonFlyer]

Phil

It does say on the plan to trim the wing LE and TE at the root to fit the fuselage, you can see the trimmed areas on Nigels website build pictures. It does look like quite a bit to trim off though.

It is a shame about the comments on the wood pack. I am not so sure about ordering it now, especially as the removable wing design needs extra wood anyway, I might go for a full scratch build.

I think I will put KC's wood list into SLEC and see what the cost is with a few extra bits to allow for mistakes etc.

[Phil Winks]

James the only extra wood for the removable wing is some 3mm ply and you sdhould note my drawings show the wing at max chord ie: no triming,

I'd hold on a week or so and see if MHS provide any feed back on these initial comments.

the lack of triangular stock, which is after all the base profile for forming the pieces Nigel refers to, is slightly dissapointing and if MHS are not intending to include it, then given the cost of posting just that and a piece of 3mm ply it would be silly not to get the whole lot from Slec or similar

Phil

[Nigel Hawes]

Just a note on the flat-edged triangle stock - it's not simply triangle stock with an egde shaved off, as this would make it too shallow.

I manufactured it on a bandsaw by putting the 45-degree angle on the 10mm sheet first, then levelling the table but instead of doing the straight cut normally, i.e. to produce a perfect triangle, the guide is adjusted to make the straight cut 4.5mm from the usual apex.

If that sounds like complete gobbledygook, which I have to say it does reading it back, I could try to take some photos of the technique if it would help make it clearer!

[WolstonFlyer]

Ahhh..I thought it was triangle stock with one side planed down.

Would planing down some triangle then sticking a thin strip on top work to bring it up to height? I don't have exotic tools like a band saw so will have to find an alternative method.

Thanks for the info Nigel, that probably explains why it is not included in the wood pack.

[Edit]Actually I could probably hand plane a 45 degree on to the edge of a 10mm thick sheet and then hand cut the width to create the right shape.

Edited By WolstonFlyer on 01/12/2012 20:51:16

Edited By WolstonFlyer on 01/12/2012 20:57:13

[Nigel Hawes]

Pure Genius! Yes indeed, a piece of everyday 10mm triangle stock with a strip of 3/16" glued on one side would have exactly the same effect.

I assure you there is nothing exotic about my workshop or bandsaw! If you saw the pile of non-usable flat edged triangle stirips I accumulated during production of the 45" Tucano under the BVR Kits banner, you would cry!

I cried frequently back in those days...

[Phil Winks]

Join the club James you'd not be suprised to find out more than half of us joining this mass build prob don't have a band saw so some alternative will be found

 

Phil

 

Edit oops Nigel got in before me lol

Edited By Phil Winks on 01/12/2012 20:58:52

[WolstonFlyer]

Nigel it sounds like you went to great lengths to provide all of the needed wood parts! As my edit above I could possibly plane the angle by hand then cut the width to leave the flat area. I might just stick an extra strip on the top.... it sounds easier!

It will be "interesting" doing this build on the kitchen table in the evenings once the kids are in bed.... I need to be very quiet!

Edited By WolstonFlyer on 01/12/2012 21:13:25

[Nigel Hawes]

WolstonFlyer -

""Great Lengths" doesn't even scratch the surface!

Each wing panel was weighed to within a gram of the opposite side, the fuselage sides were weighed within a gram of each other so they pulled in equally at the back, and only the best, softest, lightest balsa went into the kits. Each one took hours.

Looking back it was more "obsessive" than "quality control" but when we didn't have as much power available as we have now, airframe weight was more of a consideration!

It would be nice to have the time and commitment to do it all over again, but not in this lifetime I doubt!

[Phil Winks]

Nigel Despite the extra power we have these days I think going to something like those lengths would still pay dividends in the flight capability of this model.,

although I agree if you want an aircraft to fly in higher wind speeds you need a tad more weight there's a lot to be said for a floater in light ish winds for someone moving on to their 1st low winger

Phil

[WolstonFlyer]

Wow, that does sound like a lot of work. Imagine costing that into a kit today!

Well I think I am going to put in an order at SLEC for wood and cut my own parts.

Should the wing leading and trailing edges be soft rather than medium? I think it says "light but firm" on the plan.

[Nigel Hawes]

You can afford to use fairly firm leading edge panels, or as I've learned since I designed this model, a 3/16" dowel along the leading egde not only provides a uniform rounding, but also protects the panel, allowing the use of lighter balsa.

I used this method on the subsequent Fizza and Whizzza designs with pleasing results.

If you use firm leading edges, medium grade mainwing panels and soft trailing edges, you should end up with a very light and strong wing.

Ironically one of my Tucanos was used to evaluate heavy loads for the cross-channel attempt, and even at 4 1/2 lbs weight, it still flew very nicely with loads more upward momentum for stall turns and reversals etc.

So it is by no means a weight critical model, which takes the pressure off when trying to get the right balsa grades, something which is increasingly difficult these days!

I used to make an annual 600-mile round trip to SLEC, spending whole days selecting the balsa for my kits and thoroughly getting in ian Hull's way I'm sure!

[WolstonFlyer]

Thanks for the help Nigel, I will change my wood list a little bit.

I like the idea of dowel along the leading edge, I do a similar thing with CF rod on my foamies and it adds a massive amount of strength.

[Phil Winks]

James have you thought CF rod or D sect on the leading edge might just be stronger and lighter than dowel. And while I'm here I must echo your thanks to Nigel for his imput it is indeed helpful

Phil

[WolstonFlyer]

Hi Phil

I am not sure how strong D section is compared to dowel. I imagine 4mm CF rod would work but it is quite expensive.

[Phil Winks]

Basically James once secured to the leading edge D sect would be as strong as dowel as any flex would be exerted across its largest dimension and the flat edge would improve the odds of getting a secure glue bond with less glue,

That said I'm toying with the Idea of using my router table (yes a machine not everyone has LOL) to machine a LE sect from some very hard 12mm balsa planks I have. Believe it or not, rescued from a scrapped bed frame. Yes I was amazed to see it too, but I promise you its Balsa just massively hard and machines up beutifully and will add the much needed anti ding protection to the leading edge, all my models need that lol

Phil

[Delta Foxtrot]

Posted by Nigel Hawes on 01/12/2012 21:34:49:

You can afford to use fairly firm leading edge panels, or as I've learned since I designed this model, a 3/16" dowel along the leading egde not only provides a uniform rounding, but also protects the panel, allowing the use of lighter balsa.

I used this method on the subsequent Fizza and Whizzza designs with pleasing results.

If you use firm leading edges, medium grade mainwing panels and soft trailing edges, you should end up with a very light and strong wing.

Ironically one of my Tucanos was used to evaluate heavy loads for the cross-channel attempt, and even at 4 1/2 lbs weight, it still flew very nicely with loads more upward momentum for stall turns and reversals etc.

So it is by no means a weight critical model, which takes the pressure off when trying to get the right balsa grades, something which is increasingly difficult these days!

I used to make an annual 600-mile round trip to SLEC, spending whole days selecting the balsa for my kits and thoroughly getting in ian Hull's way I'm sure!

Nigel,

Nice to know that you do not consider the model to be to weight critical. My concerns about the woodpack gradings were based on reading your build articles, but I guess these were written nearly ten years ago.

David

[WolstonFlyer]

Good point about D section being easier to fix.

I think my wings will be made up of Medium balsa for the leading edge and middle panel with 1/4 (6mm) D section applied to the LE. Then soft for the TE and ailerons.

Just "tweaking" my wood list then going to do an order at SLEC including all of the outstanding hardware I need (Wheels, snakes, piano wire etc)

[kc]

Well before anyone orders from my material estimate ( page 20 here ) I hope someone else checks it!

I costed the main sheets ( but not the tiny amounts of odd sizes or the ply ) at about 29.50 from Balsa Cabin ( SLEC is usally similar prices) That's without the ply and bits of beech etc which I know I have lying around in my scrapbox. Could be up to twice that at a local model shop.

So if you get all these ply parts in the wood pack it seems a good deal at the discount price. And you get all those parts cut out although its not a tricky to do it yourself as there are very few intricate cut parts ( unlike some more recent designs fretted out of liteply ). Of course if you have plenty of balsa & ply left from other projects you might have to spend only the 29 pounds or so.

But I was still astounded at how much balsa it used and the cost! I thought it would be a low cost project.

Edited By kc on 02/12/2012 15:01:15