2013 Mass Build - general chat thread

[Nigel Hawes]

Mike -

Unless you heve already purchased one, I would say go for a lower Kv version.

Find a 400 - 500 watt motor which will spin a 10 or 11 inch prop at a comfortable wattage on either 3s or 4s. The motor I'm using on 3s has a Kv of 950, if I was looking at 4s I'd be looking for a motor of around 800 Kv.

At less than 3lb weight, this model performs well even on 350 watts (it's all we used to have 10 years ago with a 2820/10 AXI!) so don't get carried away with big wattage motors that the model doesn't need if you only want scale perfromance or slightly above scale. The only advantage of using a bigger motor is to swing a larger diameter prop, which you can't due to the undercarriage option.

Hope this helps,

Nigel Hawes.

 

 

 

Edited By Nigel Hawes on 13/03/2013 13:33:40

[WolstonFlyer]

I am going with a 3S 2200 setup probably with 2 LiPos connected in parallel for longer flight duration.

With the TGY-3542 1250Kv I was basing my prop "estimate" from the comments on the HK website.

 

One reviewer says (but I have no idea if this is accurate)

 

10x7 APC WOT 503watts 46amps

10x7E APC WOT 510 watts 46amps 9930rpm

11x5.5 APC WOT 493watts 45amps

11x5.5E APC WOT 495watts 43amps 9356rpm

 

 

I am using a 60Amp Turnigy Plush ESC and I have initially bought a 10x6E and a 10x7E Prop to do a power test with but I have not had chance to build a motor test stand with scales to also measure thrust. I also have a 9x6E to test but I think that might look too small for the scale of the plane.

 

I am fitting the undercarriage but I am making the nose leg a bit longer to (hopefully) create enough ground clearance for up to a 10 inch prop.

Edited By WolstonFlyer on 13/03/2013 14:31:12

[Nigel Hawes]

It just goes to show how the information in different forums can vary - one guy measured 52A on 3s with a 10x5 and another only measured 46A with a much pitchier 10x7!

When we all get to the final set-up stage it might be useful for the builders still seeking a motor / prop / cell combination if we all post our wattmeter findings on our chosen gear. That way there will be a good spread of info for those using undercarriage (therefore limited to prop diameter) and those without undercarriage who will have a free choice.

Our motors, ESCs and Li-Pos will probably all differ, but the info will be constructive!

Nigel Hawes.

[Mike Hardy]

Hi Wolston and Nigel, with the nose leg increased by 1/2" ( mod recommended on here) then the height from ground (incl nose wheel) to C/L of prop shaft is about 6 3/4" + whatever tilt there is. I am not sure how the Tucano behaves at rotation but I am hoping an 11" prop is safe enough. So I am going on a 11" prop. I need to tie this down so I can complete the fuselage front end. Allowing for the 3deg of side thrust then a maximum motor dia has got to be 35mm. So my motor spec will be linked to a 35mm dia can.

The next exercise is to find a motor with a bit of quality that doesn't shed magnets.

Mike.

Edited By Mike Hardy on 13/03/2013 15:20:54

Edited By Mike Hardy on 13/03/2013 15:27:12

[Caveman]

I am also using a 2200 3S setup with Emax GT2815/07 using a 11x7 prop.

I have increased the length of the undercarriage legs to give a reasonable ground clearance.

For long grass use I have fitted 70mm dia. wheels, which give a ground clearance of 50mm

For summer, when the ground will be a little harder and, hopefully, smoother I intend to try 50mm dia. wheels, which will reduce the clearance to 40mm.

At the end of the day I might try a 10inch prop, and if the u/c legs look too long I can easily make another set of legs in about 20 minutes.

Here is my current setup (not yet maidened, awaiting decent weather) 11inch prop and 70mm wheels.

Hope this helps GDB

[Mike Hardy]

I have just ordered from HK, SK3 3542 1185kV motor, 3S 4000 30c Li-Po. and plan to use 10X7E prop with a 60A ESC. I note that nearly all of the SK3 3542 range are now out of stock with an 8 week delivery. I would have preferred the 1250kV version but had to settle for the above, there does not seem a lot of difference with my application. Will also try a 11X7E prop.

Not sure where HK is but the delivery charges are high - 10 quid!!

Any comments please.

Mike.

[M4Maverick]

FTAO Nigel H

Many thanks for the pointer reference the smaller version

Mike W

[Mike Hardy]

Does anybody use XT60 connectors on their Li-Po's? are they good for 50A bursts?

Mike.

[Robin Kearney]

Mike, XT60 can cope with a constant 60A according to this page.

hth.

r.

[Chris Bott - Moderator]

Mike the very useful list here shows a max current of 45A for two minutes so for 50A it may depend on how long your burst is, and how long it gets to cool between bursts.

[WolstonFlyer]

Hi Mike

I am using XT60 on my Tucano (and all of my planes so far) but HobbyKing also have an XT90 connector rated for up to 90A if you are worried.

[Mike Hardy]

Thanks all, just ordered 5 pairs of XT90 connectors from HK

Mike

[Geoff S]

I'm sure XT60 wouldl be more than adequate. Most of the time you'll be flying on much less than full throttle.

I've standardised on 4mm bullet connectors (Batt pos male, batt neg female) for all my bigger packs and 2mm for smaller packs drawing fewer than about 15 amps. That's what HobbyKing (or is it Giant Shark?) use on their 4S packs, unfortunately they adopt the opposite polarity from me so I still have to cut them off and solder my own on.

Geoff

[Phil Winks]

Posted by Mike Hardy on 14/03/2013 11:28:56:

I have just ordered from HK, SK3 3542 1185kV motor, 3S 4000 30c Li-Po. and plan to use 10X7E prop with a 60A ESC. I note that nearly all of the SK3 3542 range are now out of stock with an 8 week delivery. I would have preferred the 1250kV version but had to settle for the above, there does not seem a lot of difference with my application. Will also try a 11X7E prop.

Not sure where HK is but the delivery charges are high - 10 quid!!

Any comments please.

Mike.

Mike Hobby King are hong kong based but if when you log on their web site you click the uk tab before searching for your requirements you will only see what they have in uk stock and postage from their uk whare house is much cheaper

 

Phil

Edited By Phil Winks on 14/03/2013 18:37:39

[Mike Hardy]

The pics show F1 fitted and held in the jig whilst the epoxy sets. Question should the sides be pulled in to meet F2 and glued before fitting Phil's F1A ? or F1A fitted first,?

Mike.

[Phil Winks]

It should be possible to fit F1a from below the fuselage once you have pulled in the sides to F2 & 3 and fitted the tailpost and turtle deck at which point I reckon it can be removed safely from the jig however don't fit the nose top sheet till F1a is in place and your happy with it

Phil

[Mike Hardy]

Hi Phil, clamping power is a problem for me - all I have is the Slec mini clamps using rubber bands.

Even wet the sides seem reluctant to pull in. What sort of clamp do you use? Should I need to use such force?

Mike

[Mike Hardy]

Found a G clamp - a lot of tension required!!

Mike

[Nigel Hawes]

I can't figure out how you need so much force when finger pressure until the epoxy sets is enough for everyone else - even with 1.5mm ply doublers!

That must have been some balsa they made your fuselage sides from...

[Mike Hardy]

Some fingers Nigel!! I am using 1 hour epoxy and I reckon the clamp will have to be in place for the rest of the afternoon! and this is with the sides well dampened with hot water. The wood is from the CNC/wood pack from MHS.

Once the epoxy is fully cured I intend to peg the sides to F2 otherwise I think the balsa will shear as referred to in a previous post.

Mike.

[Geoff S]

Mike I also used a SLEC fuselage jig and didn't find too much difficulty though I didn't have any ply doublers in place. I do have some of the small sash-type clamps widely sold at model shows on the tool stands.

I have retro-fitted doublers but mine are 0.8mm. Nigel's 1.5mm seem pretty big to me but who am I to criticise the designer? I admire his patience as well as his finger grip if he's happy to hold all in place as the epoxy sets. I left mine over-night but I do use Grip 1 hour epoxy which takes quite a long time to cure.

I didn't fit F1a until after I'd done all the other formers as well as joined the sides and rudder post. F1 a needs to be trimmed at the top to suit the curve when you pull in the top part of the sides to meet the former curve and that's much easier to do later.

Geoff

[Nigel Hawes]

Geoff -

The 1.5mm doublers are without doubt total overkill, but with no model shops around here and having to get everything sent by post, I was too impatient to wait for some 0.8mm ply to arrive so I just used what I had, which was 1.5mm. That said, the fuselage is now very sturdy as you might imagine, so it will handle a lifetime of underarm launches.

My last one gradually got weaker between F2 and F3 over its service life, partly as I used to fly it in very strong winds that none of my other models would handle (whereas the flat sheet wing seemed to cut through without fuss) but gripping it tightly prior to launch clearly took its toll in the end! This one will be much stronger but a little lighter - I might have to ballast it up a bit for such winds.

Nigel Hawes.

[Mike Hardy]

Just glued F3 to the sides still using a fair amount of clamp pressure! It you look at the second pic F3 does not meet the top of the fuselage side - is this by design? or do I add balsa to the top of F3 to bring it level with the top of the fuselage side?

Mike.

Edited By Mike Hardy on 20/03/2013 16:30:23

[Nigel Hawes]

Ahhh - now I see why you're having so many problems - you're using Heinz soup instead of glue!

Seriously though, I think it's because your fuselage sides have been cut too tall by the woodpack supplier. The normal ones do end up level with the top of F3, before adding the flat-edged triangle stock.

Will you be at the Greenacres event Mike? If so I'll bring a semi-assembled fuselage with me, made of the correct materials, and you can see for yourself the lack of effort that should be required to hold the fuselage against the curved formers.

Nigel Hawes.

[WolstonFlyer]

Hi Mike

Adding F1a made the front harder to pull in for me. I cut notches into the sides just behind F1a and F2 and glued in a 6mm square cross brace to the back of each former and into the fuse sides to help it hold in place.

My sides are hand cut from medium sheet rather than from the CNC Kit but it all still needed clamping like you have.