Arado 555 - RC Groups
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Apr 20, 2016, 08:05 PM
gke
gke
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Build Log

Arado 555


Commenced build of an Arado 555 based on that of Josef Poisinger's 1200mm version:

https://www.rcgroups.com/forums/showthread.php?t=180962

I have used an 8% Phönix airfoil instead of the original 12% to hopefully improve glide performance.

Build will be 3/4oz glass directly over foam cores using water based polyurethane (WBPU) which I have used before as a covering technique.

Propulsion will be either 2-4 EDFs or single propellor interchangeable on plug-in pylons.

Cores weigh 160gm bare without wing extensions which will be solid balsa - foam too hard to cut accurately. I am using lightweight filler to repair minor and one major (photos) hot wire cutting problems. The foam I am using sands well and I may put a light wash of filler over the wing.
Last edited by gke; May 22, 2016 at 04:25 AM.
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May 12, 2016, 07:49 AM
gke
gke
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Starting Assembly


Simple box fuselage provides a more flexible solution for joining wings, batteries and alternative motor configurations. Larger wheels than Josef's to suit the grass runways I fly from. The fuselage could have been narrower but I wanted to preserve the option of 2 x 2200mAH 3S packs.

The main wing joiner is about 2/3 of the inboard wing panel. There is a second short joiner at the back of the battery box. The joiners are glued where they overlap inside the fuselage.

In a fit of madness I also attempted to cover with brown paper today but it got the wrinkles so I have stripped the paper off and sanded it back a little. I will now cover as originally planned with glass cloth and WBPU.
Last edited by gke; May 20, 2016 at 01:54 AM.
May 14, 2016, 03:32 AM
gke
gke
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Juggling Act


Well assembly of the wings was a little bit of a juggle, aided by copious masking tape, but lateral symmetry seems OK.

Now patience as the glue cures in the foam to balsa joints .
Last edited by gke; May 15, 2016 at 04:23 PM.
May 17, 2016, 03:08 AM
gke
gke
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Cockpit


Cockpit stub built up from foam scraps and covered with a couple of layers of 3/4oz glass again with WBPU.

Cockpit proper is from the top section of a 90mm diameter drink bottle. Screwtop cutoff leaving an opening that is a perfect fit for the plastic trim from an Aeronaut folder. Rear wall of cockpit 10mm balsa with locating dowels and magnet retainer.

Cockpit diameter turns out to be 2.5M at full scale which seems reasonable for two aircrew abreast. Length of full size fuselage commonly given as 25M.

Weight of bare airframe now 595gm.
Last edited by gke; May 18, 2016 at 03:59 AM.
May 21, 2016, 09:22 PM
gke
gke
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Ready to Fly?


Finished complete with authentic covering ripples and other manufacturing defects . AUW with Turnigy D3536/6 1250Kv, Master Airscrew 8x6 3 blade prop and 2200mAH 3s pack is 1165gm. This is a little heavier than the planned 950gm with some of this due to the larger wheels for grass strips.

Josef has the CG at 312-330mm which is consistent with my calcs of 316mm or 20% . In my case there is a fuselage which changes the MAC and the CG position. How much is the question but if the fuselage was a wing section it would be 304mm so that is where I will start for test flight(s). Tail heavy flying wings are very bad .

CG position calculated using WingCGCalc. Wing Plan used is HERE.
Last edited by gke; Jun 10, 2016 at 04:51 AM.
May 23, 2016, 11:27 PM
gke
gke
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Test Flights


Test flights were entirely successful. Trims where neutral with CG at 320mm behind LE. Pitch down on rapid throttle up but not too dramatic. Hand launches are a non-event so the wheels will go to save a little more weight.

ROG sees it veering to the left due to motor torque and of course there is no rudder to correct the yaw on the ground . The drag wires that Josef suggests were in my case on the bottoms of the vertical stabilisers not the tips which I judged to be too weak. They were also not under compression so the one on the inside of the turn was dragging and the one on the outside was off the ground.

Needs to be flown fast but landings can be quite slow and comfortable .

20160524 Arado 555 Maiden (2 min 31 sec)
Last edited by gke; May 24, 2016 at 07:05 AM.
May 24, 2016, 01:42 AM
ancora imparo
jj604's Avatar
Very nice! Flies extremely smoothly Greg.

Congratulations.

J
May 24, 2016, 04:14 AM
gke
gke
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Quote:
Originally Posted by jj604
Very nice! Flies extremely smoothly Greg.

Congratulations.

J
Thanks John. It was a blustery day with the wind around 25Km/H but with a bit of speed it just cuts right on through it.

I will drag it along to indoor some time.
Last edited by gke; May 24, 2016 at 05:22 AM.
May 24, 2016, 04:48 AM
ancora imparo
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Just don't fly it there!
May 24, 2016, 02:56 PM
Registered User
Congrats on the successful maiden. I build one to Josef Poisinger's plans except from foam and it is my favorite flyer. Mine glides a loooong time. It's a great design.

Here's mine: https://www.rcgroups.com/forums/show....php?t=2092366
May 24, 2016, 05:54 PM
gke
gke
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Quote:
Originally Posted by pmullen503
Congrats on the successful maiden. I build one to Josef Poisinger's plans except from foam and it is my favorite flyer. Mine glides a loooong time. It's a great design.

Here's mine: https://www.rcgroups.com/forums/show....php?t=2092366
Thanks Pat.

I found your thread a month or so back and that prompted me to try brown paper over what is for me solid foam cores. I made a mess of it as I did not wet the paper properly so as you see I went back to glass.

Yes it glides surprisingly well and will be a lot of fun to fly. I intend trying it as a slope-soarer later this week. I can remove the motor pod to reduce drag as well but that probably won't be necessary. After that I will try 2 EDFs. Most of my fields do not permit ROG so my hand launches are more of a glide at around 30% throttle with about 4mm of up elevon on my flight mode switch. I think I may have fractionally more down angle on my motor but it does pitch down if you throttle up quickly. Of course on a launch no airspeed means the reflex is not generating restoring pitch moment to counter the forward CG.

Congratulations on your huge collection of great builds as well.

Cheers
Greg
Last edited by gke; May 24, 2016 at 06:17 PM.
May 25, 2016, 08:39 AM
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I too have some up elevon on a switch for hand launches, though it takes off just fine from grass.

I would think it would be a good model for slope soaring. Mine will thermal under the right conditions.

I haven't have much luck with brown paper over solid foam cores. A solid foam core isn't as stiff as a built up foam wing and thus is very susceptible to warping from uneven drying.

I plan to build another soon with drag rudders.

Have fun with yours!

Pat
May 25, 2016, 11:25 PM
gke
gke
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ROG Modifications


Pat and Josef have convinced me to persist with ROG attempts. They are having no problems so I have made some mods that may help my efforts.

I now have a single wheel still in the position shown in Josef's schematics and have removed the rear one so that the wire skids, which are on the vertical stabilisers, are held firmly on the ground. The AOA has been increased to around 5 degrees. A piece of velcro has been put in the aperture where the rear wheel was to assist with hand launches.

I have mixed rudder into the elevons in addition to ailerons. The convention and habit of most pilots on the ground is to use rudder only for ROG ground handling and this may have been part of the problem in the test flight takeoffs. Elevon differential has also been set quite high at 60% for testing.
Last edited by gke; May 25, 2016 at 11:42 PM.
May 26, 2016, 09:30 AM
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I have no skids on mine and it has to take off into the wind. Control on the ground is somewhat random.
May 26, 2016, 10:10 PM
gke
gke
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ROG Modifications


Quote:
Originally Posted by pmullen503
I have no skids on mine and it has to take off into the wind. Control on the ground is somewhat random.
Tried it with skid wires and no rear wheel this morning. Grass was not freshly mown so it was a bit tufty. No problems at all with holding a good line. Only issue is landing; if you come in a little quick then the high AOA set by the front wheel tends to re-launch it .

I have reduced the amount of up elevator on launching by half to around 4mm. It now has less tendency to "pop up" on a hand launch.

CG with the added area of my fuselage now seems good and I am able to do slow glides. Trims are neutral. You are correct Pat mine should also thermal and will certainly be happy in light slope lift.
Last edited by gke; Jun 10, 2016 at 04:55 AM.

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