HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old May 09, 2013, 11:53 AM
Registered User
Italy, Emilia-Romagna, Plaisance
Joined Aug 2005
245 Posts
Discussion
Arado 555 "Amerika bomber"

Hallo!
I'm asking advice about some important details of my scratch built Arado 555.

FYI my Arado 555 is a foam-made test model for an "all-wood" version built by my friend Luigi.

The model's main structure is done and only the four ESCs and cables are missing.

Name: CIMG6461.jpg
Views: 99
Size: 28.5 KB
Description: Name: CIMG6319.jpg
Views: 101
Size: 201.7 KB
Description: Name: CIMG6479.jpg
Views: 137
Size: 53.4 KB
Description:
Name: CIMG6474.jpg
Views: 114
Size: 48.9 KB
Description: Name: CIMG6477.jpg
Views: 104
Size: 46.4 KB
Description: Name: CIMG6448.jpg
Views: 115
Size: 28.7 KB
Description:

At this moment I'm worried by:

A) The correct location of the C.O.G.: VERY IMPORTANT IN FLYING WINGS.

B )The real performance of the four 55 mm. EDF.

C) How to (safely...) take-off: bungee launch or four-wheeled dolly?

Here's some technical details of my model:

Wingspan: 152 cm. (59,8")

Weight in flight: between 3.300 and 3.350 grams (116,4 to 118,16 oz.)

Four 55 mm. (50 mm. fan) HobbyKing EDF (RC Lander clones):
http://www.hobbyking.com/hobbyking/s..._Version_.html

Total max power: about 1.300 ÷ 1.400 Watts

Total static thrust: from 2 to 2,4 Kgs (70,5 to 84,6 oz.)

Power-to-weight ratio: about 390 Watts /KG.

Weight/thrust ratio: 1: 0,6

I hope that the choosen airfoils (CJ-5 at the root and CJ-4 at the end of the main wing panel), will be good even if "more than outdated"
(http://www.aerodesign.de/english/pro...file_s.htm#cj5)

What do you think of the C.O.G. location that I've found with this software???

http://j.mp/18wmOvr

What is your advice for the maiden flight: bungee launch or dolly?


Thank you!!!

ettore
quenda is offline Find More Posts by quenda
Reply With Quote
Sign up now
to remove ads between posts
Old May 09, 2013, 01:09 PM
Registered User
Colchester UK
Joined May 2004
411 Posts
Ettore great model!

I love these flying wing designs. As you probably know I have a large 6 turbine engine Arado 555. I can help with the cg. Mine is 795 mm back from where the leading edge line meets the centre. My plane is 3.35m wingspan. I needed all the batteries for turbines and Rx up front with over 1kg lead.

Good luck

John
John Wright is offline Find More Posts by John Wright
Reply With Quote
Old May 09, 2013, 01:19 PM
Registered User
andrecillo76's Avatar
Heidelberg
Joined Oct 2009
379 Posts
Ettore,

regarding C) I would always go for a bungee launch. Dolly can bring some new problems in a maiden, such as bouncing up and down on the dolly... Bungee launching is easy. The wing has normally sufficient speed to be operable right away. And if point B) should apply, you can fly the wing smothly down to land it.

Regarding the CG, well no idea as it depends strongly on the aerodynamic design.

Cheers,
Andrés
andrecillo76 is offline Find More Posts by andrecillo76
Reply With Quote
Old May 09, 2013, 01:38 PM
Registered User
miniphase's Avatar
Kent, UK
Joined Nov 2004
869 Posts
might be worth making yourself a little scale 'chuck glider' to help determine the cg
miniphase is offline Find More Posts by miniphase
Reply With Quote
Old May 09, 2013, 07:04 PM
less is more
Knoll53's Avatar
United States, CA, Marina
Joined Sep 2006
2,826 Posts
Quote:
Originally Posted by quenda View Post
Hallo!
What do you think of the C.O.G. location that I've found with this software???
What is your advice for the maiden flight: bungee launch or dolly?
Great model !

So Luigi has already built this plane?
Did he use the same airfoil?
Do you have anehedral at the wing tips?

So this is basically a plank and your use of the flying wing calculator should be good. I have a graphic method that I use (with some success) and will check your work in the next day or two. Your choice of 18% is good for a first flight. It should be pitch stable with most any airfoil. The trim settings is the question.

This is a rather heavy plane. For flight testing I'd suggest a short powerful bungee launch (without the use of power). Launch from the hip with all of the elevons trimmed out for very slow flight. That is with the elevons deflected up. Have your maximum elevon deflection set at 20 degrees. Place the tow hook at 45 to 60 degrees in front of the CG. This should yield a significant climb upon release. Just launch and land as a glider as safely as possible. You will most likely have to hold nose down to fly safely. Do not fly slow. You may have to hold full nose down to get off of the bungee without a stall, so be ready. If it climbs very steep upon launch, then feed in nose down immediately. It would be nice if it were to climb at a 30 degree angle on launch. After a successful first flight, adjust your trim settings and throws just a little and repeat until it flys really well.....then add power. With the towhook at 45 degrees, it should climb on launch with any trim setting. If you need lots of up elevator just to fly level, move the CG back.

And here is another idea. Do those motors come off???
If they do, take all of the weight you can out of this plane, set the CG again for the light version, and test fly as a glider only. Once you determine a good CG from that testing, use that knowledge and trim settings for the heavier powered version and bungee launch again. Even with power, use a bungee. Launch without power, then after release, feed in the power.

Here is what a powered bungee launch looks like. Andres launches from the ground, I prefer launching from the hip just to increase ground clearance as soon as possible.
Erstflug Horten IV in Holz (4 min 32 sec)


Here's launching from the hip.
1st Soberanes launch with the Manatee (2 min 24 sec)


At this point I have just 3 words for you.
Fly ! Fly ! Fly !

Kent
Knoll53 is offline Find More Posts by Knoll53
RCG Plus Member
Last edited by Knoll53; May 09, 2013 at 07:50 PM.
Reply With Quote
Old May 09, 2013, 11:47 PM
Registered User
andrecillo76's Avatar
Heidelberg
Joined Oct 2009
379 Posts
Kent,

I normally bungee also from the hip, bit the IV is too big to keep level . The Arado look complicated to hold. Might be worth takling a shot from the ground...

Cheers,
Andrés



Cheers,
Andrés
andrecillo76 is offline Find More Posts by andrecillo76
Reply With Quote
Old May 10, 2013, 12:58 AM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
3,278 Posts
One of my favorites!I bought a Traplets kit of Chris Golds design,with the intention of adapting it to the twin engined V3,but the laser cutting was terrible.
Re the launch,maybe a plastic pipe ramp would work.It could be an awkward one to hold,and the drooped tips would make off the ground problematic.
http://www.rcgroups.com/forums/showa...5&d=1174744978
Stupot46 is offline Find More Posts by Stupot46
Last edited by Stupot46; May 10, 2013 at 03:17 AM.
Reply With Quote
Old May 10, 2013, 03:32 AM
Registered User
Italy, Emilia-Romagna, Plaisance
Joined Aug 2005
245 Posts
Hallo!
As always great informations from the RCG forum!

John, of course I know your amazing 6 turbines Arado 555 and I've watched the 2 videos many times.
Another impressive model is the Richard Jones' 6-EDF Arado.
Both models are very good flyers.

If I want to confirm the C.O.G. of your big model I need to know some more measures (see attached drawing):

- Main wing panel span
- Root chord
- Tip chord (of the main wing panel)
- Sweep or angle ((of the main wing panel)
- External wing panel span
- Tip chord (of the external wing panel)
Name: COG-check.jpg
Views: 106
Size: 39.4 KB
Description:

I suppose that the leading edge angle on your model is 45°........in my model is 49°.

Of course I also need a lot of weight in the nose of my model and for this reason I will fly with one big 6.200 MAh. 4 cells li-po battery (687 grams) and another 1.600 Mah. Li-fe battery for RX and six servos.


@ Miniphase
The idea of a chuck glider is good. I will ask my friend to do some hot wire cutting ASAP.


@ Knoll53 and Andrés
Fantastic model and very good videos!
The "all-wood" version of the model is far from finished.......but it looks already very beautiful!
Name: CIMG6470.jpg
Views: 128
Size: 59.3 KB
Description: Name: CIMG6472.jpg
Views: 168
Size: 62.3 KB
Description: Name: CIMG6473.jpg
Views: 132
Size: 57.4 KB
Description:

The airfoil is the same: CJ-5, an "auto-stable" airfoil with a good reflex.
If I remember well the external wing panels have a -4° geometric twist.

I may be wrong but I consider the Arado 555 a sweep flying wing and not a plank.
Yes, I can remove the four EDFs in just a minute........and I can fly the model as a glider. Without the motors the model's weight will be about 2,5 Kgs.

Bungee launch from the grass could be dangerous for the very thin Arado's wingtips and a launch from the hip could be a problem.
So I'm thinking about a pretty big ramp: two simple wood rails of about 2 - 3 meters.

@ Stupot46
Thank you for the ramp drawing!!!
I have purchased the Chris Gold's Arado 555 short-kit and plans from Traplet. I have assembled the whole frame and I've abandoned the model since it is too small for my taste and I don't like expensive 30 mm. EDFs.

Grazie mille!

ettore
quenda is offline Find More Posts by quenda
Reply With Quote
Old May 10, 2013, 06:34 AM
I don't like your altitude
Stupot46's Avatar
Joined Sep 2011
3,278 Posts
That is some serious woodwork!.I presume you guys have done all the design and plans?
The ramp design could easily be extended; the pipe is available in 3metre lengths,or you could join shorter sections internally to make transport easier.Much lighter to handle than wood;if you use the push fit style bends with 'O' rings it will be strong but easily dismantled.
Please keep us updated with your progress,including the balsa build.
Stupot46 is offline Find More Posts by Stupot46
Reply With Quote
Old May 10, 2013, 09:36 AM
less is more
Knoll53's Avatar
United States, CA, Marina
Joined Sep 2006
2,826 Posts
Quote:
Originally Posted by quenda View Post

If I remember well the external wing panels have a -4° geometric twist.

I may be wrong but I consider the Arado 555 a sweep flying wing and not a plank.
Yes, of course, it is a swept flying wing. To my thinking, a plank may have some sweep, has an autostable airfoil and no wing twist. I assumed that this was the case with your Arado.

So with your -4 degrees of wing twist, your CG may be different than what is provided by your wing calc. program. Still the 18% indicated previously mentioned should make the plane nose heavy, which, for a test flight adds safety by providing good pitch stability and good yaw stability. It is true that you may needs lots of up elevator to glide level, but it will be otherwise stable and flyable. Flying wings can tolerate a very nose heavy CG, but will have severe problems for aft CGs.

The CG of this flying wing was eventually moved back about 1 1/2" if I remember right.
ME 263 Komet - maiden voyage (1 min 39 sec)


Kent
Knoll53 is offline Find More Posts by Knoll53
RCG Plus Member
Last edited by Knoll53; May 10, 2013 at 02:10 PM.
Reply With Quote
Old May 10, 2013, 11:29 AM
Registered User
andrecillo76's Avatar
Heidelberg
Joined Oct 2009
379 Posts
Ettore,

nice airframe! I love wood

Quote:
Bungee launch from the grass could be dangerous for the very thin Arado's wingtips and a launch from the hip could be a problem.
So I'm thinking about a pretty big ramp: two simple wood rails of about 2 - 3 meters.
Sure, the tips would not like being bungeed from the ground. We use PVC pipes from the hardware store. They are maybe 1,5m long. That should be enough to get the needed clearance:

Speed flight with a Horten flying wing rc-model of the Schapel SA-882 (4 min 28 sec)


Andrés
andrecillo76 is offline Find More Posts by andrecillo76
Reply With Quote
Old May 10, 2013, 11:44 AM
Registered User
Colchester UK
Joined May 2004
411 Posts
Hi Ettore

Glad to be of help.

The info you were after

- Main wing panel span 1750mm
- Root chord 1190 mm
- Tip chord (of the main wing panel) 870mm
- Sweep or angle ((of the main wing panel) 45 degrees
- External wing panel span 650mm
- Tip chord (of the external wing panel0 120mm

Sorry made a typo on the wingspan 3.050 not 3.350m

Dont forget the nose will generate some lift and move the CG forward a little.

John
John Wright is offline Find More Posts by John Wright
Reply With Quote
Old May 13, 2013, 03:23 PM
Registered User
Italy, Emilia-Romagna, Plaisance
Joined Aug 2005
245 Posts
Hallo!
John, this is what I've found using your numbers:

http://j.mp/10mdCq8

As you can see the program C.G. is located at 765 mm........only 3 centimeters forward compared to your real model (795 mm).
Now I can say that the program is reliable and I can trust the results at least for the first flight.

Note: assuming that your giant-sized Arado weight is 35,5 Kgs.........do you fly with a 145 grams/dmq wingloading!!!????!!!

Thanks again.

ettore
quenda is offline Find More Posts by quenda
Reply With Quote
Old May 14, 2013, 05:43 AM
Registered User
Colchester UK
Joined May 2004
411 Posts
Ettore

Yes the weight is correct. The wing was weight tested with 140 Kg. It is very strong despite being made of balsa and ply with foam wing tips. As you can see it flies well, takeoff is not very long with only 19 Kg thrust. The first flights were with retracts down because the pneumatics are not strong enough for the weight of the 4 wheel bogie. I have refitted with some heavy duty prototype electric ones so when we fly next hopefully we can get the wheels up.

John
John Wright is offline Find More Posts by John Wright
Reply With Quote
Old Jun 09, 2013, 02:47 PM
Registered User
Italy, Emilia-Romagna, Plaisance
Joined Aug 2005
245 Posts
ARADO 555 "Small" maiden flights

Hallo!
Here is the maiden flight(s) of a small version of the Arado 555 built by my friend Luigi.

Arado 555 Small - Voli di collaudo/Maiden flights (5 min 16 sec)


The model is exactly 50% in size (75 cm. wingspan) compared to the "big brother" (150 c. wingspan).

As you can see after two bad starts, on the third launch the model flies very good even with a single EDF and a 1.300 mAh. 3 cells li-po.

No need for the "vectored-thrust-corrector".......but it's cool!

Now I'm pretty busy with my dayjob but ASAP I will post some pictures of an ultra-streamlined dolly that I'm building for my big Arado 555.

Bye!

ettore
quenda is offline Find More Posts by quenda
Last edited by quenda; Jun 09, 2013 at 02:50 PM. Reason: YT link correction
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Ho XVIII (Horten 18 Amerika Bomber) - Design/Build Thread Cyberman Electric Ducted Fan Jet Talk 59 Aug 01, 2011 07:42 PM
Discussion Arado 555-3 "Amerika" bomber by Chris Golds quenda Scratchbuilt EDFs 29 Mar 05, 2011 08:02 AM
Sold Scratch built Arado 234 scale electric twin German Bomber PRICE LOWERED! rcdude01 Aircraft - Electric - Airplanes (FS/W) 2 May 30, 2010 12:09 AM
Sold Scratch built Arado 234 scale electric twin German Bomber PRICE LOWERED! rcdude01 Aircraft - Electric - Airplanes (FS/W) 0 May 23, 2010 12:37 PM
Has anyone done an Arado 234 jet bomber? RobZ Scale Kit/Scratch Built 7 Sep 02, 2003 07:27 AM