TopModel CZ Avia? - Page 6 - RC Groups
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Mar 17, 2010, 07:02 AM
Born Again Idiot
MooSey-UK's Avatar
Im hopefully completing the wings tonight. I have'nt uploaded any photos yet as I wanted to show the servo/rod/horn fit as a sequence. should be done and pics here by the weekend

RJ ref the ruddervators. I ran the snakes (control rods in plastic tube) down the fuz virtually as the instructions state.
Ensure the ruddervator servos sit low enough in the fuz to accomodate the control rod connectors supplied (if you are using them).

Run the snakes down the fuz and UNDER the V-tail ply mount. I found if (and I did .......) I mounted the snakes as per the instructions , which go through the little gap between the ply mount and the fuz then the control rods are a little high and don't align with the ruddervator horns.

At the front the snakes run over the balsa support supplied. Leave enough rod exposed between the snake plastic outer and the servo arm. This allows for the radius sweep of the servo arm and associated flex of the control rod.

Use 5min epoxy blobs to secure the snake outer at the front on the balsa support and at the rear on the V-tail ply mount. Mix in microballons if you want to lighten it.

The instructions don't call for support midway but it would be wise. i stuffed a bit of folded up foam down the boom. It's light and holds the snakes nicely.

Not sure what you mean by this question RJ:- "Also on your hold down of the rear elevators. ?

Do you mean the control horns? You simply cut a slot and glue them in with epoxy. Make sure they they are vertical in relation to the V-tails. check out the (slightly blurry) pics in post 69.
The control rods are simply bent at 90 deg. The horn holes are very small and the wire just fits through. You can but another bend in after or glue on a bit of rubber tube etc if you are worried about the wire coming out the hole. But it won't though

Sorry if I've just written a load of waffle and taught you how to suck eggs!
Im not sure entirely what you were asking about. I'll get some better (clearer pics!) of the linkages at the back for you.
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Mar 20, 2010, 07:20 PM
Born Again Idiot
MooSey-UK's Avatar
Managed to finish the wing servo installation today.

Before installing extensions to the servos it's always a good idea to set your flap and aileron pairs side by side and centre them symmetrically. Also you really want to test your servos before lopping off the connector!
When happy it's time to get them into their new homes.
Last edited by MooSey-UK; Mar 20, 2010 at 08:23 PM.
Mar 20, 2010, 07:37 PM
Born Again Idiot
MooSey-UK's Avatar
Time to get horny and install the control horns!
The supplied jobs are cut gf board. Nice and light and fit for duty.
The control surfaces only need a scalpel to make the cut outs. Obviously you want to mark up each surface squarely and equally. The aileron horns will locate the clevis pin hole over the hinge whilst the flap horns are set back to achieve increased flap travel.

All control rods are made up to be exactly matching lengths once you have tested for desired travel.
Last edited by MooSey-UK; Mar 20, 2010 at 08:26 PM.
Mar 20, 2010, 08:18 PM
Born Again Idiot
MooSey-UK's Avatar
Wings are now virtually complete. They only need lateral balancing and the servo covers fitting. I think I'll use the supplied ones and add a white stripe to the underside to match them in and aid orientation.

I've set my throws as suggested by the instructions. I have not employed any esoteric glider mixes. I'll see how she fares on a test flight before fiddling.

I also managed to fit the props and program the motor ESC.
To reiterate my components I've used a Turnigy 3542-1100kv outrunner at 45A max rating. A Hobbywing 40A switching BEC deals with the motor and provides Rx power. And a Loong Max 3000 25c 2S lipo.
I wanted a 2S (7.4v) setup for the following reasons -
It's lighter. For less weight than a 3s I can employ a higher capacity battery.
A higher capacity battery will deliver more current without struggling than a lower capacity at a higher C rating.
The 7.4v being dropped to 5v at the SBEC will generate less heat. Not so important with a switching BEC but a consideration.
A 2S battery will swing a larger prop.
It's cheaper

I had a 13x7 Graupner folder in stock and this looked fine on Drivecalc.
Here's a pic with it running up on a wattmeter. Thats about the 5th long run to show average figures.
Should provide ample performance for this glider. If I want it to go mental I can always fit a smaller prop and 3s lipo for more power. In fact I may get another spinner and matched prop for 3s for windier conditions when the extra weight and punch will be handy.

Only got c of g balancing and final fettle/check before awaiting a nice day for her maiden and some pics of her.

All in all it's been a very straight forward and pleasant build.

Maiden report to follow when I launch her into the blue
Last edited by MooSey-UK; Mar 20, 2010 at 08:33 PM.
Mar 21, 2010, 08:52 AM
Registered User
Thank you again for the detailed build thread. Really nice job.
I am really looking forward to hearing your flight report.
Good luck on the maiden...and thanks again.
Cheers Mike
Mar 21, 2010, 02:03 PM
Born Again Idiot
MooSey-UK's Avatar
I've just carried out a c of g balance which turned out to involve more fuss than I anticipated.
With the ESC/battery/Rx laid out as suggested in the instructions she was very nose heavy.
I've ended up moving the Rx behind the servo tray in the boom aperture, which is fine by me as it puts more distance between the ESC.
I had to slide the battery all the way up to the servo tray under the wing. Im still at the forward range of c of g given.
My motor is the same weight as the recomended motor and so is the ESC.
I only need to add a 5g weight into the tail (under the V-tail mount) and it's fine. I'll test it at the forward c of g then move back as required.
Be aware though it seems the c of g cannot be set by battery position alone. Im also using a lighter battery than a more usual 3s 2200maH etc.
Granted my prop at 13x7 is bigger than the recomended 10x6 but I don't see that being too much the culprit....

So bear in mind when you fit your servo tray you might want to push it right back to give you more room to shift the lipo around.

I balanced the wings too. 2g in the port servo aileron well and the Avia sticker inboard on the port wing.

Awaiting a sunny day now
Mar 22, 2010, 07:34 AM
Born Again Idiot
MooSey-UK's Avatar
Got a LM 2250 25-35c 2s lipo on order. Can't stand the idea of adding tail weight. This battery is nearly 40g lighter which should balance the c of g nicely and the high C rating should still sustain a 35A draw. For less than 15 quid it's a no brainer.
Mar 23, 2010, 04:49 PM
AMA 7224
Leadchucker's Avatar
Finally mine is on the bench after finishing up the other plane. Or was I just waiting for MooSey to do the footwork?? any case the project is underway.
Mar 24, 2010, 01:02 PM
Registered User
Nice pictures there Mike. I haven't done much work on mine, but this weekend I will be geting alot done. I flew last weekend, so..............
I do have all my 4 sevos in place and mounted through the wings. OMG whata drag getting the wiring through the wing ribs. There done now, so the rest will go nice. They took some work and time. Came out good though.
Mar 24, 2010, 02:46 PM
Born Again Idiot
MooSey-UK's Avatar
Good stuff RJ.
Mar 24, 2010, 03:05 PM
Born Again Idiot
MooSey-UK's Avatar
well dang me I do believe I got her maidened today........
Hold your horses though it was'nt very constructive.
I took a trip to my local slope as that's what I do. I loaded the Avia in case the wind dropped off which is the 1st reason I got it. (2nd being off the flats when I visit my folk and 3rd being to practise for 200m Esoaring comp).

Anyway, the wind crossed up then dropped off so it gave me the perfect excuse to rig up the Avia. I spent some time double checking everything.
1st chuck and headed down into a dive. It took all the up trim travel and a bit of stick back to maintain level. A quick and safe landing was made.
I temporarily adjusted the ruddervator servo centres to compensate. I found if you look end on you could lay a ruler across the top so the tail section looks like an inverted wing.
Naturally the wind started to blow up now.
I wanted to test the motor and tail trim so relaunched. On my power set up she is not short of climb. I can't really make an educated comment though as the wind was now going 15mph ish and crossing the slope. She really did'nt like these conditions but to her credit remained fully in control. Picked up a nice lick of speed coming off a climb but unfortunately my prop was windmilling. I think I need to loosen the prop nuts a tad.
I dedcided I was'nt going to achieve any meaningful trimming so quickly tested the crow braking. Fine, I used +/- 10mm travel elevator and set up for 30% down elevator compensation which just put her nose up very slightly and scrubs off any speed.
Landing a plane on a slope with decreasing lift and a crossed wind is always going to take comittment. To her credit the Avia came through the approach in control and carrying good speed for safety. The crow stopped her dead into wind and she settled very gently.

I noted the ailerons had plenty of authority in these conditions set up to max throws as per the instructions. I also set up CAR which undoubtably helped in the non ideal situation.

For me it's nice I know she flys and I have an idea where I want to start trim tweaking. I can't tell you how well she thermals or turns on the rudder etc etc because I don't know.

Mar 24, 2010, 11:46 PM
Registered User
Excellent info, thanks all for posting your experience while building this plane, I've been circling around a 2-2.5 meter electric glider for a long time now, and the Avia seems really nice, only my building skills that worry me ( drilling wing bolt stuff give me nightmares )

I might have missed it, but whats the empty weight of the Avia, roughly? I'm looking to do some motorcalc on it.

Very envious of you Avia owners

Thanks again for sharing! I'll be keeping an eye on this thread

Mar 25, 2010, 06:36 AM
Born Again Idiot
MooSey-UK's Avatar
Manufactures and shops state 1.1 to 1.3 Kg dependant upon motor/battery combo. I need to weigh mine but im waiting for another lipo to arrive.
anywhere around 250w should give a brisk climb. It would'nt be difficult on 3s to go way over 300w+ so you could go vertical if you so wished.
Mar 25, 2010, 10:15 AM
Registered User
Sounds like you had you hands full Mike. Good info on the maiden. I will be working from tonight , tomarrow and weekend on mine a few ahours each night. I'll be ready next week. I can't wait.
Sounds as though we're looking for light winds Mike? Nomore then 10 mph?
This time of year here in NY its breezey.

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