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Woodstock

Valenta Thermik XL

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Woodstock

Maidened my Thermik XL today  :) .  4m wingspan mouldie.

 

(The yellow on the wings is flourescent:  it's funny how the camera just can't handle it...)

 

 

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Woodstock

Power is an Hyperion glider motor (GS 3032 series).  They have an after-market extra mount with a bearing that supports the rear of the motor (as well as the standard front mount).  I really like that.

 

Battery is a 4-cell 2250 mAh Turnigy Nano-tech 65-130C LiPo.  100A Turnigy ESC, and double UBECS (just in case the 3 - 5 amps isn't enough).  Two resistors with alu heatsinks prevent them fighting with each other.

 

Cranked prop yoke allows the prop blades to nestle closer to the fuz.

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simonslim

Nice install Chris, looks like a more than adequate set-up, how did it perform. I see you have camoed the prop/mustache. 

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Woodstock

Performs great.  Although I was flying in solid lift conditions (i.e. sport plane conditions), and this is supposed to be my light air thermal chaser, so I don't know yet how she will do in that role.  Seems promising enough.  It's nice and light (normal lay-up, no carbon, and no lead on board at all). The power system was just tested to see if it can penetrate the wind, which it did with ease, so that should be fine (I'm just looking for an on-board launch system, not hotliner performance).  It was drawing 75 amps on the static bench.

 

Yeah, I HATE mustaches with a vengeance  :angry: ... 

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f3fman

Looks great. I would have thought that 75amps on a 4S the performance should be quite sprightly ?

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Gromit

Great to hear all went well . Lovely neat install  :thumbsup: .  Video soon please :)

 

  Stu.

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Woodstock
Looks great. I would have thought that 75amps on a 4S the performance should be quite sprightly ?

Yeah, should be.  I need a calmish day to judge really.

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f3fman

Can you explain how you are connecting the resistors to prevent the Ubecs fighting ?

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isoaritfirst

Lovely Chris, the thermic does look a very pretty model. Where does the battery sit?

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Woodstock

Two small value, high watt (0.47 ohm 15 watt) resistors are connected in series with each output and then connected together for the final output (on one side). This allows the regulators to work independently of each other but share the current demand fairly equally.

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Woodstock
Lovely Chris, the thermic does look a very pretty model. Where does the battery sit?

The battery is that blue thing visible under the red heatsink of the ESC (ESC is mounted to an aluminium battery hold-down plate)...

 

I succeeded in getting it to balance where I wanted to start with (9 mm further back than the rear-most factory spec) with no added ballast.  

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simonslim

Hi Chris, are you using the SPC port, I use this on every plane I have, piece of mind against brown-outs. Works better than fingers crossed.

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Woodstock

Ha, Simon, funny you should mention that:  for some reason or other, I'm getting voltage telemetery with this plane.  Now, in answer to your question, I don't use the SPC port on the Hitec receivers, as I run LiPo's + regulators on every one of my gliders, and I found that in most cases there seems to be a "conflict of interests" between the regulator and the SPC port..  So, I don't usually connect it ...  Not sure what's going on here with this set-up though?

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simonslim

I have a fly lead + and - coming off the lipo before the regulator, straight into the spc port then the regulated supply into the normal battery/servo port. I have run up-to 10s into the spc port and 5-6v regulated into the battery/sero port on all of my planes as I noticed that on full-house jobbies, especially the Alpina that when coming into land when ailerons, flaps, spoilers, elevator and rudder are doing their bit the tx module would star beeping which is warning you that you have low rx power. With the method I use the rx will not brown out due to power drain from the servo's. 

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Woodstock

HI Simon, yeah, I did the same, but it seemed to me that the system wasn't enjoying regulated power coming in one port and unregulated power coming in another (SPC) port...  So all I get now displayed on the radio is the regulated battery voltage, which never changes of course:  which is as useful as a cat flap on a submarine...

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GP

Thanks for posting the technique for getting the two UBECs to not fight each other.  I've never heard of that solution before, very interesting.  I once built a glider with two UBECS fighting each other because I was not aware of the issue.  One UBEC died, the other kept working fine, and it was months before I noticed!   Nowadays I use Jeti linear BECs to avoid that problem.  But they are considerably bigger (and more expensive) so it is great to learn there is another option. 

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Woodstock

GP, I would just use a big enough UBEC to start with.  In this case my parcel with the bigger ubec was lost for a while in the post, plus I had two smaller ones "in stock"...

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RosscoPK

If you do want to monitor the voltage from your lipo Chris, run it through a relatively high resistance potential divider scaled to suit 2S, 3S etc, down to 5V when charged, then into your V monitor. It will vary proportionally as your lipo does, simples :) You can pick values so only 1mA or less could be drawn and tiny 1/2 watt resistors can be used without any heat to dissipate. Alternately, use a 10k linear pot instead of one of the two resistors to allow your to tweak it for total accuracy.

PS Lemme know when you're selling this one ;)

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Alan Letcher

This looks a great model Chris.Any idea if it will fly in say 20 mph wind?I did my maiden with a Shadow yesterday first time with a large moulded glider with electric.I am now hooked.

I feel the Thermick would be a great winter project for me

Alan

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Woodstock

Alan she penetrates very well into wind.  She has a greater wing loading "stock" than the very latest F3J planes which are coming out very light now, but it just means a smoother flight in my experience (those F3J planes are in any event almost never flown without ballast).

 

(ps. mine MIGHT be for sale..  I realize I now have two almost identical planes, and while it's nice to have a spare, maybe it's a bit extravagant :unsure: ..)

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