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Ren's Tucano Build


Ren
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Well, I've signed up for it, so I'd better start somewhere, and where better than to order up the plans and wood pack to build this thing. It was useful getting the extra discount as a mag subscriber - didn't realise that until I went to the checkout. Lo and behold - after only a few days wait a box arrived in the post.

A very light box

Surely this can't contain everything? Its nowhere near the size I expected!

Silly me - its only when I opened it that I realised it was only the moulded cockpit canopy. Quite a size - its over a foot long. I didn't realize just how big the model was going to be.

tucano1.jpg

Ah well - hopefully the remaining box with the plans and the wood will arrive soon and I'll really be able to see just what I've committed to building. In the meantime I'm going to hunt through the other threads to see what sort of power trains others are going to use and then it will be time to spend some more money

 

Edited By Ren on 06/12/2012 00:03:51

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Well - second parcel arrived in the post today. A big corrugated cardboard parcel containing two packs of wood - one laser cut and the other one with all the blocks and planks of wood. I opened it up looking for the plans - and they were still nowhere to be seen.

Oh well - I'll have to wait a little longer before I'll really know what size this thing is going to be and what the construction will be like.

In the meantime I'm going to try and order up the power train.

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Hi Ren, I am also building the Tucano, but wont be joining in the mass build due work commitments. I got the canopy and 3 days later the CNC pack etc, but was dismayed not to have the plan with it, called MyHobby and the nice lass said it is being sent separately. So looks like another week or so before I can start. Tad frustrated, surely they can get all the bits to arrive within a day or so of each other and not weeks.

Ho humm

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Yes - frustrating as it is difficult to know exactly what I should be ordering. So I've probably another week before the plan arrives.

Still - I've had a good look through the postings from the other threads about what power trains people are using and have bitten the bullet and placed the following order with those dear people at Hobby King.

1x Turnigy D3542/5 1250KV Brushless Outrunner Motor
5x Turnigy MG90S Metal Gear Servo 1.8kg / 13.4g / 0.10sec (Like to have a spare!)
1x TURNIGY Plush 60amp Speed Controller
1x OrangeRx R610 Spektrum DSM2 6Ch 2.4Ghz Receiver (w/ Sat Port) - (hope this will work ok with my Spektrum DX6i Tx)
1x OrangeRx R100 Satellite Receiver (just in case I need the extra range!!!)
1x Reciever/System Switch

I've got a couple of 3s Lipos so I hope to use one of those.

Can anyone tell me the best way of switching off the LiPo battery other than just removing it? The connectors that I'm using are very hard to connect/disconnect and I'd feel safer if I was able to switch off the electrics completely when the battery is in and before I'm ready to fly. The receiver switch seems just to isolate the Rx and not the motor - or am I just confused?

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I would strongly advise against putting a switch between the LiPo and the ESC.

You would need a very hefty switch 80A - 100A to be safe as all of the current between the LiPo and ESC will be going through it. You just don't see switches like that in elecric flight models, they all just use the battery connector. Also, this creates another point of failure in the power system. If that switch fails you lose the plane.

I suppose you could make up a "link" section in the +ve line using 4mm bullet connectors or a battery connector then remove the link to isolate the battery from the ESC but that is introducing a lot of connection points in the system that could fail.

It is also not advisable to store or charge Lipo batteries in the plane because of the potential for a fire is something goes wrong with the pack.

You also do not need a receiver switch, it is just another thing to go wrong.

This is not like an IC plane there is never any need to have the RX turned off while there is power connected to the ESC, in fact that is very dangerous.. there is a chance "however small" that the ESC could power up the motor and if your RX is turned off with a switch you will have a live model with fast spinning bit on the front and not much chance to do anything about it!

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At the risk of sparking a hot debate on the issue, I would agree that on 35mhz one should not switch off the TX as there is always the risk of interference from another Tx. On 2.4 I have seen too many incidents where the Tx is knocked firing up the prop, if you switch of the tx you disable the esc and reduce the risk of this, there virtually no risk of interference on 2.4 as your tx and rx are. Bound with a unique code. I argue my case!

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If you have your failsafe correctly set at zero throttle and then switch off the TX, yes you are correct nothing should happen and there is very little chance or any reason for the motor to burst into life. Like you say the RX is bound to only that TX so interference should not cause any issue.

I even think it says in some ParkZone manuals that is does not matter if the TX is powered off before the plane flight pack is removed (I am sure I have seen that).

But why would you want a switch between the ESC and the RX? I cannot think of any situation where you you would want the flght pack connected but the RX switched off ?

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Wow - thanks WF & Tim - I didn't mean to start an argument! Shows what a diverse lot we are.

I can now appreciate the problems of putting a main power switch in so cross that idea off my list - I wondered why I couldn't find any on line.

I think that I will use a Rx switch, I know its one more link in the chain, but I would just feel safer being able to switch it off to prevent accidental damage to me if the Tx speed control is touched when everything is ready to go.

I've not flown radio control since a single channel model which belonged to a friend about 40 years ago. All my modelling was control line using using a Cox 0.49 or my diesel AM10 which I still have and still runs. Since restarting modelling when I retired I've built a Spitfire from a Guillows kit that I converted to run on Electric power and radio control, and bought an ARTF cessna electric model - neither of which I have flown yet. I'm looking to join my local club in Crawley and then hope to get flying come spring.

In the meantime I'm also starting to build an Easy Built 50" SE5 kit which will be powered by an old OS.40FP that I picked up cheaply off EBay. That should keep me busy over winter!

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Personally, I know the logic says switching off the Rx ought to prevent the motor starting in all circumstances.
However, my procedures are ALWAYS to disconnect the main battery whenever the model does not need it connected. With that battery disconnected I know I'm safe, there is no safer conditon so that's the best one for me.
Some people just leave the Tx off, and theres similar logic there to leaving the Rx off. BUT there is a possibility, however slight, in both cases, that some local interference could get into the servo wire, into the ESC and start up the motor. (Have you ever heard the din that a mobile phone can make when interfering with PC speakers for example?)

The other issue with leaving the LiPo conected and switching off the Rx is that it makes it all too easy to leave it that way after a flight, whereupon the Lipo becomes slowly discharged and far too easily scrapped.

So, if there's a convenient battery hatch, then it's easy to connect and disconnect the LiPo directly.
If there isn't, then it's fairly simple to add a removeable link that is accessible from outside the model.

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Well got my plan on Friday, so started 'bashing' today. Bit miffed that the balsa pack doesnt have 12mm triangular balsa and as for the 2 joiners for the wings, absolutely useless, who ever cut them really needs to stop drinking, a coiled up length of hosepipe is straighter than the ones they have 'cut'. Will post a pic later today if i can.

However the fuz is going together ok, but wont be able to do anymore til just before xmas if lucky

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Posted by Mark R on 10/12/2012 10:52:16:

Well this is quality control on the wing brace.......hmmm has China been asked to make these parts? Probably not as their quality control is better.....

20121210_104334[1].jpg

Mine were the same. I emailed MHC and a few days later I got a replacement set, direct from SLEC. I also mentioned the lack of triangular balsa and was ent a a small piece, enough for the front fuselage, but not the turtle deck. At least MHC respond to these issues, hopefully the quality / content of the woodpacks will be improved for future buyers.

Dave

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Crikey! That CNC cutting is shocking!

Add that to the fact that the stuff you ordered was sent in three separate packages that arrived at different times - you can sort of see where the UK model trade is lacking.

Good luck with the build. I was going to order the CNC and wood packs - but not so sure now. sad

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Hi David and FF, emailed Myhobby and they are sending the triangualr balsa and new CNC ply parts, which is good. Dont let it put u off FF, i am looking forward to the very slow build of mine, between work and family. The price aint too bad so it is worth going for FF.

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I was going to leave opening the CNC pack till after the plan arrived (STILL waiting - boohoo) but given your comments Mark and FF I opened up the plastic bag with trepidation.

Well - maybe I'm the lucky one, or yours was the last thing on friday rush job, but all my CNC stuff looks pretty good and well cut - good straight lines and nice and square!! Don't know about the triangle bit though as I've still no plan to reference against.

What I did receive today from Hobbyking was a well packaged box with all my drive train goodies!! Can't wait to try them against the plan.- when it eventually arrives!

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  • 5 weeks later...

Wow - a month since my last post. Well that the Christmas holiday season for you. I've now got the plan, the wood, the drivetrain and went to get my building board out to start but found that it had warped, and unless I wanted banana shaped wings I needed to do something about it.

Having removed the old 1" battens I replaced them with new 1.75" ones with screws man enough to hold them in place, tightened them up and lo and behold - a flat surface to work on. Next time I must remember to store the board properly and not use it as an extra storage space in an overcrowded garage!!

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  • 2 weeks later...

Build has now started with the wings. Glued up with odourless medium CA and 5 min epoxy for the wing tips. On the first wing I used far too much glue and it all oozed out the bottom onto the plastic covering on the plan. I'll rmember that for the other one.

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So I've put marking tape on the wings to show the extent of the planing needed to make it easier to do just the parts that need planing.

dsc_0073.jpg

Its a pity in a way that the ailerons were pre cut as it will make the trailing edge harder to shape

properly

.dsc_0074.jpg

Razor plane worked well and didn't take too long to get the shape, and then final sanding to finish it off. Slots are for the ply dihedral braces. I'm not putting an undercarriage on this.

I was a bit concerned when I weighed the wings - 93g for the left and 96g for the right - 3 grams difference seems a lot to me. I should have weighed them before shaping them to see if it was the wood selection or my shaping that was at fault - will the weight difference matter?

dsc_0075.jpg

and this is the shaped wing at the wing tip. Wasn't sure wether to thin down the wing tips or not. I stopped after making a slight thinning as I can always take a bit more off before I cover them if anyone corrects me!

Job for tomorrow is to decide about using torque rods as described on the plan. or horns and to join the wings together

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Ren I would adjust the imbalance by removing a small hole in the heavy wing before covering to decide how much to remove use a scrap piece of balsa of about the same density as a trial peice if the section removed is from the centre panel about 2/3rds out it shouldn't affect strength and for 3g its not going to be a significant amount to be removed anyway

alternately you could go the other way and add some weight to the lighter panel by insetting a very small amount of lead and setting it with epoxy

on reflection I'd prob go the second route

Phil

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