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Depron Alpha Jet

My first build project - A scratchbuild

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CrosstownTee09/10/2012 09:30:11
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65 forum posts
66 photos

I found a free for non-commercial use plan on rcgroups.com, with an excellent construction guide made by a guy who calls himself 'Dreamcatcher'. He's French and is actually called Pascal. I contacted him a few times and he's the most friendly and helpful Frenchman I've ever met! cheeky

Right, the specs:

It'll weigh around 550grams (1 pound 3 ounces?)
Wingspan a bit more than 73cm (29 inches)
Length 95cm (35 inches)
1 Hitec HS81 for the elevator
2x Hextronic HXT900 for the ailerons
a 30A ESC
a 2212/ T 2200kv Brushless Outrunner
a 2200mAh 3S LiPo
a lot of 6mm Depron
and some other small parts.
No landing gear .. which bothers me a bit. If it flies well, I might consider putting retracts on this bird.

Here's a couple of pictures from my build; you can find more in the album I created on this site. (I guess you can find them by clicking on my profile?)

aj006.jpg

aj027.jpg

aj045.jpg

aj051.jpg

aj061.jpg

aj069.jpg

aj073.jpg

I'm now waiting for the canopy lock hatch latch to arrive, and a better (6x4) propellor. Then... it's maiden time! smile o

GrahamC09/10/2012 10:56:32
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1240 forum posts
196 photos

Looks fantastic!

Are you going to paint it? A coat of water based Polyeurethane varnish will go a long way to toughen up the depron for not much weight. Combined with some tissue paper it will really protect the Depron when you belly land, and the mud will simply wipe off!

I'd at least put some colour on one of the wings! It will be hard to keep orientation on it if you don't! Especially against a grey sky!

Edited By GrahamC on 09/10/2012 10:58:01

Radge09/10/2012 11:09:57
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322 forum posts
48 photos

Wow! That is your first? I can't wait to see your next one!yesteeth 2 Welcome and good luck with it's maiden flight.

CrosstownTee09/10/2012 11:30:30
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65 forum posts
66 photos

Thank you! blush

I'll definately paint it... if it flies! laugh
I'm not going to put all that work in it, if it isn't flying properly... cheeky

The livery will very likely be this one:
**LINK**

Olly P09/10/2012 11:33:18
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3215 forum posts
181 photos

Hmmm...PSS.....

Phill @ Elite Workwear UK09/10/2012 11:55:39
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201 forum posts
31 photos

I like that! - very nice - looking forward to the flight report!

Roy Mundy13/10/2012 15:11:18
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453 forum posts

yes I like it A LOT! .......................A nice build You have done a great job.

Was the build tricky or did you find it ok?

Is there any chance of a link to the plans i would love to have a go

Regards Roy

CrosstownTee13/10/2012 16:41:18
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65 forum posts
66 photos

Hi Roy, thank you!!

I found it really ok (it was my first build, I have no clue whether this was difficult or easy blush)

I haven't maidened the plane yet though; I don't know if it will fly laugh Still waiting for a canopy lock to arrive. (if I had more balls, I would've taped the canopy and done the maiden anyway... but I'm too chicken... postponing... surprise)

The plans and construction guide you can find right here:

**LINK**

It's the top 3 links you want; the construction guide, the assembly drawing, and the parts file.
The construction guide is very good, although near the end he tends to go really quickly and doesn't mention a couple of things... but I'll let you find out yourself wink

Also, read the thread completely; handy information, and at the end of the thread you'll find some conversation between me and the designer as well. All very helpful.

Good luck!

Edited By CrosstownTee on 13/10/2012 16:44:31

Roy Mundy14/10/2012 19:29:50
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453 forum posts

smiley Thank you for that ...................I will get my current plane finished and I will have a go at this one.

Keep the photos coming and let me know how the maiden goes.

I'm sure you will be really impressed with it.

Regards

Roy

CrosstownTee17/10/2012 07:08:10
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65 forum posts
66 photos

Hi,

Voila, the canopy has been installed!
That thing is never going to let go anymore! cool
 
aj074.jpg
 
aj075.jpg
 
The 6x4 prop has been installed as wel, so the jet is ready for it's maiden flight.
The weekend coming up seems very promising... 20° predictions... 6km/h winds... nice!
Expect a video after Sunday! laugh

Edited By CrosstownTee on 17/10/2012 07:16:23

CrosstownTee19/10/2012 21:04:58
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65 forum posts
66 photos

Since the weather is not turning out as they predicted (hmm... what's new)... I decided to start to paint anyway...

 

Like Graham suggested, I first covered the entire plane in PU varnish.
It reacted a bit with the UHU POR glue (made it look green! face 15), and here and there I'll need to re-glue some small areas. (really small; maybe just not glued well in the first place).
Apart from the reaction, the varnish seems to have really given the jet a nice, harder cover. Thanks Graham!
 
Then... the paint... lol. I found some 15 year old acrylic paint (from art school a long time ago) but it still works... nerd
 
First... the blue:
 
aj077.jpg
 
 
aj078.jpg
 
Later, when it's dried up, another thin layer of blue; and then... the black!
 
Greetz!
T.

Edited By CrosstownTee on 19/10/2012 21:05:07

Roy Mundy20/10/2012 09:44:17
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453 forum posts

yes She's looking really good I like the paint design.

I bet it will fly really well.

A great job done I bet your really pleased.

CrosstownTee21/10/2012 00:17:16
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65 forum posts
66 photos

Thanks Roy, I'm really pleased so far indeed. The work is giving me a lot of pleasure! laugh

 

I've done some more colours.
 
Only the white is left to do now; not only the current white areas, but also the lines inbetween the colours (they have to become as hair sharp as possible... don't know how to achieve that yet! blush)
 
aj079.jpg
 
 
aj080.jpg
 
 
aj081.jpg
 
 
I wonder if I should add, on top of the pain, another layer of varnish?
Anyone?
 
Maybemaybe maiden tomorrow.. maybemaybe...

Edited By CrosstownTee on 21/10/2012 00:17:28

Simon Chaddock22/10/2012 19:53:42
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5683 forum posts
3021 photos

Do you know how much weight the paint/varnish has added?

With Depron I am always surprised how much (in percentage terms) even a simple paint job can add.

CrosstownTee22/10/2012 22:36:14
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65 forum posts
66 photos

Hi Simon,

I just weighed the plane and I almost fell over!

Originally, with all gear in place (including the battery) the plane was around 550 grams. (19,4 oz)

Now, with the paint job almost finished (and I still need to add another layer of varnish afterwards), it already weighs 628grams!!! (22 oz)

That's more than 10% of it's own weight added already... Wow! surprise

On the other hand... she's becoming a very pretty bird (I think)... and the power on board will be more than sufficient ... smile d

 

 

Edited By CrosstownTee on 22/10/2012 22:36:44

CrosstownTee25/10/2012 07:27:47
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65 forum posts
66 photos

 

Some detail pictures, now the white paint has been done as well.
It's not perfect, but with free hand (is that the right expression?) I thought it wasn't a simple task... I'm quite happy with the result though smile
Especially the tail parts have worked out well I think. De places where the depron was a bit rough because of the sanding were the most difficult to paint. I realise that my preparation on those parts should have been a bit better.
 
aj082.jpg
 
 
aj083.jpg
 
 
aj084.jpg
 
 
aj085.jpg
 
 
aj086.jpg
 
 
 
The only thing missing now is the decal of the emblem of 50 years of Belgian Airforce, but that's for some other time.
Ow, yes, and the cockpit needs finishing too.
 
I just want to desperately find some nice weather, daylight and no wind now, so I can get this thing in the air! cool

Edited By CrosstownTee on 25/10/2012 07:28:09

Radge25/10/2012 08:10:46
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322 forum posts
48 photos

Very Nice! Here's hoping all goes well for the maiden. Good luck yes I'm going to look for this plan and see if I can adapt it for a SEPECAT Jaguar. I used to fly them.

Dave Bran25/10/2012 08:31:13
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1896 forum posts
5 photos

VERY nice looking model, well done.

A few technical comments:-

The motor position lowered below the Fus centre line makes it and its wiring vulnerable to grounding damage during landing, esp crud entering the motor and mechanical impacts to the point where the short black shrink sleeve covers the transition from colour PVC insulated connection wiring into the lacquered motor wiring Also, the bearings in 2212-6's have a hard time anyway, so be prepared for a very short bearing life if not kept clear and clean.

Additionally, that low motor will put the prop very close to flesh if you hand launch from the Fus, and launching and then the delay of powering up isn't ideal. I use a left handed across the body discus movement holding the left wing using part throttle which allows my right thumb to be controlling the flight surfaces right from the release (Mode 2). It will likely have too much torque reaction on lots of launch throttle. My Mig gets round this by having one half of the all flying tail kicked up to counter it.

You will find some people in forums saying that a 2212-6 will not survive with a 6x4. I have found this not to be true, in fact it is my combination of choice, with currently seven in use, all hand launched belly landed..

With the weight of a 2200mAh etc it is wing loaded quite highly, so will likely slide a fair way with a fairly hot landing speed, esp in no wind. My similar size and motored Mig 29 uses only a 1000mAh 3S and flies for quite long enough, but was built specifically to avoid rearward weight allowing this smaller size with no ballast. You might like to reinforcing tape cover the lower ground touch points as depron isn't ground friendly. (or a couple of top coats of poly "C" there)

Finally, try to pick a day with SOME wind, as wind over the nose will help get it away and trimmed, and assist landing.

Good Luck!

CrosstownTee25/10/2012 21:08:11
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65 forum posts
66 photos

Thanks Radge, you actually flew a 1:1 Sepecat Jaguar?

Dave, your 'few' technical comments are very welcome, I appreciate your advice very much!

Today, after work, I decided it was time for a pre-maiden flight. Just me and the plane; no cameras; a bit of wind and no rain. perfect trimming and adjusting weather smiley

Oh. My. God.

This plane flies so fast. (Well.. you should know this is my second plane; my first being a very slow trainer glider)..
As I threw it in the air, it needed a little bit of left trim on the ailerons, and one or 2 ticks elevator up.
And then it just went... I mean it really went!

"Just gently" is apparently not in this bird's dictionary; it makes barrel rolls so fast... Crazy!!!

Straight up in the sky... rolling about... loopings... no problem. But actually sending it the direction I want it to go... no way.

And so I lost control. I had to turn the throttle down, or the jet would disappear behind the horizon...

I then walked 15 minutes through the fields.

I found it on a freshly cut mais (corn?) field. But a bit more scattered than I had hoped for.

3 main pieces, and some bits. Fortunately everything can be fixed by glueing it back together, and no hardware, except for the propellor, has been damaged.
As we speak there's only the nose to be epoxied back onto the fuse actually smiley

Shame; not really flown it properly yet, and already damaged... but this is the only way I will learn, I guess... I'll need to get studying on how to adjust the travel of those ailerons... because they must be travelling a bit too far laugh

Roy Mundy26/10/2012 15:31:42
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453 forum posts

crying 2 CT Sorry to hear about your maiden flight !

The plane looked beautiful ...............what a fantastic job you done.

I will certainly be building one of these at some point in the near future.

Hopefully you will get her all repaired and up in the air again, It sounds like to me you need to put in some low rates on those ailerons and add some expo to slow the response up a bit until you get used to flying her.

Are you in a flying club? is there anyone who can set the model up for you?

Dont be put off by your crash, you will learn from it, and maybe try building a slightly slower model something like the polaris, which again looks great but maybe a bit less responsive.

Keep us updated

Regards Roy

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