2013 Mass Build - general chat thread

[Nigel Hawes]

More aesthetic than aerodynamic. But they can look a little ugly if they're too big - they have probably allowed a generous gap to cater for the various types of covering.

[Sy]

Edited By Sy on 11/04/2013 12:38:27

[Sy]

Here is my latest Tucano finished today. This is my 4^th since the plan 1^st appeared all those years ago. I have gone from Permax brushed with a brick of a Nicad to the latest which has 400 watts of brushless, 11x7apce prop, 51mm Irvine metal backplate spinner, 40a esc, 3300mah 3S lipo and an all up weight of 2lb 12oz. Built as per the plan as I have never felt the need to change anything apart from adding the ply fuselage reinforcement.

 

I chose the 2007 display scheme as I doesn’t seem to have been done to death and it stands out. Model took longer to cover than build! All black, red, white and blue markings hand cut from oracover/profilm. Roundels made using a compass cutter and solartrim. Lettering sourced from a vinyl lettering supplier on ebay, all other markings handmade on printer and decal paper. I will be adding pilots and cockpit detail once it arrives from Vortex, in the meantime, current canopy has been "borrowed" from my other airframe.

 

 

Edited By Sy on 11/04/2013 12:54:38

[Colin Leighfield]

That looks great Sy, as you suggest it's the first one I've seen with that scheme.

[Mike Hardy]

Hi all - where can I obtain a 50mm aluminium prop spinner suitable for a 5mm shaft. Motor SK3 3542 1250kV

Some 5 years ago a chap in the UK started to make these and advertised in RCMandE I purchased one and they were very good quality but no longer have any info. Hopefully someone on here can remember.

Mike.

Edited By Mike Hardy on 11/04/2013 19:20:06

[WolstonFlyer]

Hi Mike

I got mine from HobbyKing, it is yellow plastic with a nice alloy back plate. They have several other colours, black, red, white.

You can also get 50mm spinners from SLEC in their online shop.

One thing though, the spinner does not fix to the shaft, the prop adapter does this and holds the prop and spinner in place.

[Nigel Hawes]

Mike -

I've just got hold of a 50mm aluminium spinner from George Worley at 4-MAX and it looks very nicely made. It is for folding prop use, but the advantage is that you can try various different blade diameters and pitches as several blade sizes are available separately.

I must admit I've never needed to use a folder on any of my Tucanos, I just set the ESC to "hard brake" and stop the prop horizontal for landings but now I have one I'm going to try it and experiment with different prop sizes to get the optimum performance from my 3s set-up.

I'm at work right now so I can't send you any pictures but you will easily find it on his website at www.4-max.co.uk (I think that's right!)

Nige.

[Ian Newton]

Or Giant Shark do this one Mike, if you want an all Ali one

**LINK**

[Colin Leighfield]

I got two from Giant Shark with aluminium back- plates, one red and one black. Think they're Irvine? Very good quality, I've used them before in larger diameters.

[Robin Kearney]

I managed to carve the wings tonight and I have to say Nigel is right, it is a quick jobs. I was expecting a right faff but it was all done before I knew it.

I was thinking about covering, are most people going for film? Would glassing it add too much weight?

[Mike Hardy]

Hi Robin, I am going to glass my wings using light weight glass fibre and PolyC, reason my theme is to be the 2013 B of B scheme hence a painted finish. I don't think film takes to enamel very well especially painting by hand.

Question: 14g Torque rods what is the thread on the end M2 or 8BA?

Mike.

[Colin Leighfield]

As I was painting mine I used a traditional sanding sealer/dope/tissue finish, very tough on a solid balsa airframe like this. Also if you want to stick with film, you can paint it if you brush it with "Prymol" first. Some of the scale guys do this, they cover with an aluminium finish film, Prymol and paint, then scuff the paint here and there to expose the aluminium in a natural kind of weathered/wear pattern. You've definitely got choices, it's up to you!

[Trevor Rushton]

I tried Profilm on my fuselage but was unhappy with the result, so took it all off and used 17g glass fibre and interior varnish. Its so much easier than resin abd profilm. I found that mixing the varnish with talcum powder helps to fill the weave and reduces the number of coats. Smells good when you rub it down! car spray for the finish. Mine is a bit of a composite affair as I kept the Profilm on the wings.

Having seen some of the schemes that others have posted, I am toying with stripping the wings and redoing the whole thing though - gives me a chance to use some of Tim's rather good looking decals.

She had her maiden flight last week - a bit too windy really but I managed one (slightly irregular) circuit - promises well.

[Ian Newton]

Hooray! Despite rather strong and gusty wing I had the maiden flight today. All went quite well considering the conditions. Take off was a doddle with only a short taxi required. I had to add quite a few clicks of up elevator and a couple of left. I found elevator response perfectly adequate but would like a little more aileron response - must look to see how much more travel I can coax out of the setup. Landing went well despite the strong winds and I managed a respectable touchdown and rollout despite the turbulence. In flight it felt a litttle twitchy (though again the conditions didn't help) so will probably play with the C of G a little as well. No shortage of power, however. All in all I think I shall enjoy flying the Tucano, especially in better weather!

Edited By Ian Newton on 13/04/2013 18:59:53

[Nigel Hawes]

Posted by Robin Kearney on 12/04/2013 23:30:56:

I was thinking about covering, are most people going for film? Would glassing it add too much weight?

Robin -

As the answers already posted suggest, glassing the model is a perfectly suitable finishing method if it's the one you normally use. This is not a weight critical model; when we didn't have the power availability we have now, things had to be kept light and I made the wing less tapered to gain a few more square inches of wing area! But now the power is readily available, anything up to 4lbs AUW is fine.

Having flown mine several times now, I can confirm that making the wing more scale in planform doesn't affect the flight characteristics whatsoever, and having experimanted with a few different prop sizes I was a little surprised at the results!

Basically for anyone not having started their Tucano yet, taking an inch off the REAR taper and half an inch off the FRONT taper at the wingtip will give a much more pleasing wing shape, and although the ailerons will have to be re-cut from the original CNC laser line, I actually made mine a lot narrower in order to achieve a more scale roll rate as on full rates my last one looked rather silly doing "twinkle"rolls - having rolled a full-size Tucano it takes between one and a half and two seconds to do the full 360 degrees depending on the aircraft (yes they DO differ in responsiveness believe it or not!)

On the power front, for anyone not using an undercarriage (which limits the prop dioameter to about 11 inches) I would advise a low Kv motor (around 750-800) and a large prop of 13" or 14" diameter with quite a low pitch. My best config so far is a 13" x 4" which draws about 365 watts on my 3s 2x2200 ma/h Power Plus Li-Po pairing - and at around 8C, the pack barely gets warm.

This set-up limits the model's speed to "just above scale" but with a very comparable vertical climb from level flight. What amazed me in the full-size Tucano was when pulling it up vertical for a stall turn, the decay of airspeed seems very late due to it's momentum, and at the top the large diameter prop really blows it round on its axis when you kick the rudder - for some reason on the model with the 13 x 4 behaves very similarly.

For anyone wanting speed, then a 12 x 6 or 11 x 7 is fine, this makes the model behave a little like an Acro-Wot with a .40 i.c. up front - I make this comparison as I was flying around with one! I'm sure the theorists out there will be able to tell me that my theoretical maximum speed on the 13 x 4 is less than 40 MPH, but it was overtaking a DMU on a nearby railway line travelling at linespeed, (i.e. 60 MPH) - so somewhere the correlation between theory and practise falls over somewhere!

All in all I'm extremely satisfied with the various upgrades this model has had (ply fuselage doubler, greater wing taper, intermediate former mounted motor, low Kv outrunner and large diameter / low pitch prop) - I just wish I had had this knowledge and available hardware 12 years ago when I designed it - but it's clearly never too late to breathe new life into an old and outdated design!

Nige.

 

Edited By Nigel Hawes on 13/04/2013 19:14:34

[Ian Newton]

Just received the pictures from yesterdays maiden flight (Thanks Bob):

Moment of truth

 

Airborne

 

Strong gusty wind made landing hairy

Edited By Ian Newton on 14/04/2013 12:43:30

[Nigel Hawes]

That looks fabulous Ian - especially the middle shot - great angle!
In calmer conditions you'll love it!

[Ian Newton]

Thanks Nige. I think so too. It must make you feel good seeing and hearing of so many enjoying your creation - and so it should. I must say I am really tempted to make a new set of wings as per your recent posting. As I used Phil's removable wing modification it would't be too much work. I will have to give it some thought and decide on prioities. I had put aside my intention to build Tony Njhuis 72" Lancaster, for which I have everything ready to start, while I built the Tucano. I thought the extra practice of building from plan on the Tucano would be beneficial before commencing the Lanc, as I have only built a few completely from plan before. At least I am starting with the MyHobbystore CNC wood pack and plan on that one,rather than buying the wood and cutting it all myself.

[Nigel Hawes]

It's a huge honour Ian. All a designer can ever hope for is that his designs give other modellers enjoyment and satisfaction and the Tucano seems to have done this, with thousands being built worldwide and many having had more than one over the years!

It would be an interesting addition to have a spare wing, but as you seem to like very responsive ailerons I'd stick to the original aileron size, even though this means cutting diagonally through the 1/8" rear spacing strip as I had to on mine. It's not as daunting as it sounds!

Nige.

[Phil Winks]

Posted by Nigel Hawes on 13/04/2013 19:12:30:

Basically for anyone not having started their Tucano yet, taking an inch off the REAR taper and half an inch off the FRONT taper at the wingtip will give a much more pleasing wing shape, and although the ailerons will have to be re-cut from the original CNC laser line, I actually made mine a lot narrower in order to achieve a more scale roll rate as on full rates my last one looked rather silly doing "twinkle"rolls - having rolled a full-size Tucano it takes between one and a half and two seconds to do the full 360 degrees depending on the aircraft (yes they DO differ in responsiveness believe it or not!)

Nigel If I'm reading this right the wing should end up 1 1/2 inches narrower at the tip ?? with this reduction in wing area will this mean slightly higher landing speeds ? or is it insignificant ?

Phil

[Nigel Hawes]

Yes Phil, that's correct - 1 1/2" less tip chord from the same root chord.

Obviously the model weight dictates the wing loading but even on a flat calm day I haven't noticed it coming in to land any faster, you have the luxury of knowing it isn't going to stall, so you can slow it up a lot more than some other wing types on approach without any frights.

When you think about it, the mean chord reduction is only 3/4", so I've probably only shaved off around 30 square inches of wing area, which is barely significant at my AUW of around 3lbs.

When I load it up with a heavier battery arrangement for windy conditions it may show up, but then the landing airspeed will be significantly higher for the same groundspeed in such conditions so it will probably land even slower.

Nige.

[Ian Newton]

A very close guess Nige - by my calculations the total wing area was 0.234714m² (364in ²) and would be reduced down to 0.212492m² (329in^{2 )} i.e. a reduction of 9.5% to 90.5% of original so that is a reduction of 35in². Using these figures and knowing the finished weight of your model will let you work out the wing loading in each configuration.

[Nigel Hawes]

Thanks Ian! But I don't really do much number crunching these days, I just slap things together and see how they fly - never a dull moment

All I know is that various people have used flat sheet wings from 10 oz per square foot right up to 40 oz per square foot wing loadings and they still seem to work fine, so that does for me!

Nige.

[Ian Newton]

Best way really, unless you're an aerodynamics expert (counts me out!). A combination of experience, gut feel and it looking right no doubt works well for you - I don't have sufficient of any other than maybe knowing if it looks about right but I am learning slowly

Edited By Ian Newton on 14/04/2013 19:54:31

[Robin Kearney]

Thanks for all the great information in the build blogs guys, I've just had my suspicions confirmed that the laser cut fus. sides are too tall. And I now understand what people mean when they talk about about cutting off the bit of the motor shaft when using a bolted on prop adapter. It is now very clear how that could puncture a battery, I've been scratching my head about that for a while!

I'm pondering a removable wing, I think I'm going to go for a bolt in the front and a pair of dowels sticking out of the back into F3. Couple of questions arrise, should I re-cut F3 out of Liteply or similar because it will now be holding the dowels and therefore flightloads.

Secondly, what is the best way of mounting the dowels into the wing, I've seen a picture of Chris Botts' Whizza which looks like the dowels are just let into the under surface of the wing, would this be strong enough, or should I build up the top surface of the wing with some 3/8" or similar and drill holes for the dowels from the rear?

Hope that makes some sort of sense!

r.