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Mark's TN Hawk Build


Mark Elen
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Hi all,

This post is really just a place holder and start of my Build Log of the TN Hawk. Being a bit of a chicken when it comes to making a load of different sized ribs and also there being jig tabs, I've opted for the CNC pack along with the Vac form set, TN's plan and TN's Retracts

For the fan, I've gone with the 1000kv 8s jobbie from HK along with the HobbyWing 130A onto Speed Controller - we will see how that combo works out. The fan spec says 4.6KG at 110A

The speed controller specs say 130A continuous, 160A burst.

I've also got a turnigy 5A HV BEC, I'm not 100% yet about this, as I note Tony went with a separate Battery (at least the plan shows it) for the receiver.

Anyway, a build log isn't a build log without photos:

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In that last one I've got the fan bolted onto the workmate ready to commence testing.

Looking forward to this, but I'm just playing with bits as the Ballerina has to be finished before I start the build proper on this.

Cheers

Mark

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I finally had the courage to connect it all up tonight and have a little play, unfortunately, I had forgotten that the ESC comes default as Heli and it has a 'ramp up' time. No wonder nothing happens until half throttle then it just accelerates away. At least I can now label up the wiring (I had it running backwards - just swapped two of the 3 outputs over) program it up tomorrow and have a proper test of it.

Forgot to say, I've decided to use AS150 connectors for the power train and these were soldered on to the lipos when they arrived a few weeks ago. I've also made up a link cable to connect POS to Neg on the lipos, but, since doing that, I've got a multi balance board for the iCharger that will allow me to charge these 2 as if it is one 8 cell in series, so I may just remove the link and go male on one neg to female on one POS.

It sounds Awesome.

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Cheers

Mark

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This morning I have finished off the programming and initial testing of the fan for now. I've got to say that it was pretty painless. Just plugged the programming board in, changed from Heli to Fixed Wing, changed the start up time from 15s down to the lowest it would go (4s)

One thing that threw me was the ESC won't operate with the programming board plugged in, but no issue, powered down, removed the board, powered back up and sucess. It will now spin up from a low throttle and responds as expected through the range.

The photo below shows it pulling 72.6 Amps at full chat, but this was with the lipos at 3.85v per cell storage voltage.

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That's now achieved what I wanted, it's proved the power train, I'm happy with the results and can now get on with one of the most satisfying parts that I find of any build, all the thinking that goes on beforehand ironing all of the details out before any wood hits the board.

I've pretty much decided to follow Martin's idea of using slim wing servos for the elevators and for all of the wing servos, that way, only the servo arms will be stuck out and on view. The rudder will follow TN's Hawk and be closed loop with the servo mounted above and to one side of the fan.

Cheers

Mark

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Hi Gary,

Many thanks for your comments, I will do that when I have a chance, I ordered this fan unit while it was reduced in price at HobbyKing, managed to pick it up for £56.

The HK specs are 3200w Continuous, 3500W Burst for 10 seconds, Max thrust 4.6KG

I'm not dead set on this fan, because of the length of the tube on it is going to make lining up and fitting the thrust tube to it difficult and also it only has 4 stator vanes. I do like the fact that the fan itself is Ali.

When the fan turned up and I realised the tube issue, I then ordered the same fan as Tony is using from HKs Global Warehouse, it has turned up, but minus any fixing hardware. The fan itself is plastic. I ordered a 90mm fixing bracket set from TurbinesRC in France, it sort of fits, but the seats where it will bolt to the bearers isn't going to allow it to fit flat. (I'm not going to be able to post any photos of this, this week)

So you can see, I'm in a bit of a quandary which fan to fit, I had just about decided on the first one, but maybe I need to test them both and then decide. Thinking about it, I could make up some spacer plates for 'fan 2' to make the bracket fit better.

When I get a chance, I'll post up the photos.

Thanks once again for posting, it has got me thinking again

Cheers

Mark

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Hi Martin,

I'm looking forward to your updates with anticipation👍

Here are the photos of my options:

Fan 1 - this was the discounted one from HK. Pros - metal fan blades, nice flat mounting lugs. Cons - is going to be hard to install and remove once the thrust tube is in and the model finished due to the length of the housing unit, only 4 stator vanes

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Fan 2 - this is the same fan unit used by Tony - Pros, It definitely works, I don't need to go any further. Decision made.

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Now I just need to sort out how to make them mounting lugs straight. I was thinking about making a small spacer plate to go inbetween the two halves on each side.

Cheers

Mark

 

Edited By Mark Elen on 14/10/2017 16:03:44

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Hi Mark, mine tightened right up flush but left a slight bend in the pair. Not worrying about it since I am using T nuts in the bearers so the M3 cap screws will sort this out. Relieved the bearers a bit to take the heads of the csk screws holding the mounting straps together. My fan will be about the last thing to fit after painting leaving just the tail end bit to tidy up. It goes in easily from the hatch (with the top of F6 removed).

Word of warning on this model. After gluing in the intake supports the whole thing has warped quite a bit so am trying to sort it out with a few saw cuts in the balsa, wetting, and leaving under weights to dry out over night since I would like to glue the intakes to the fus next in preparation for the lettering masks to be fitted prior to spraying the thing red. It is in white primer at the moment.

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Hi Mark,

They were trimmed first and fitted well. After treatment in the airing cupboard with weights they may now go on OK with some spots of C.A. then r/c modeller`s glue. I suppose that I could sand down the centres to get a better fit but probably shall not bother. I just knew that I should have made GRP moulds from these and the nose before I cut them. I also hate working with ABS.

Now attempting to fit the mounts for the ESC, Rx, switch, nav. light flasher and Rx batteries and keep them out of the way of the air intakes.

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Mark,

Since we seem to be the only two posting on this project so far I would suggest that we combine the threads rather than jumping from one to the other. It would remain in your name of course. I can direct people over to yours.

Should have some pics of the tentative radio installation soon.

The intakes should now fit OK.

Sprayed a couple of coats on the hatch and the paint match looks quite good.

Martin

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Hi Martin,

Many thanks for the info, I've got no problems if you want to do that. It will be a little while before I start the build proper, when I start, it will be my usual 'photo heavy' build blogs. Feel free to post up on here if you want to.

If the mods want to change the title to something like ' TN Hawk Builders', I'm cool with that too.

Regards

Mark

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Thanks for the pointers guys👍 I will take those spacers out.

Today I have charged up the lipos, and set the power train up on the bench. At full chat, it is pulling 114.71 Amps giving 3436.7 Watts. That doesn't look too far off does it?

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The biggest question is how closely calibrated is the watt meter?

I'm pretty happy that this will be adequate based on the fact I was having to hold onto the workmate to stop it moving😂

Cheers

Mark

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Looking good (Mark/Martin) . As an aside, I managed to borrow a thrust meter and was pleasantly surprised that my Schubeler EDF unit was was producing similar thrust (on 8s) to the HK unit at approx 600 watts less showing on my Watt meter.

I'm debating on the Hawk . Decisions , decisions!

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