Micro MIG 15 Mod -> Silent Seagull EDF - Page 5 - RC Groups
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Jun 22, 2012, 04:23 PM
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Janusz Jawien's Avatar
Sorry it did not go as planed.
I think that you tried to tackle too many good things at the same time.
IMHO it would be a good idea to start from scratch and may be focus on profile RC glider
with the shapes of a seagull and add the propulsion later....
Just my two rupies...
BTW you have a really great place for maidens!! Gentle slope with tall grass! WOW!
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Jun 23, 2012, 08:33 AM
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thnx guys..!

It was definitely tail heavy. strange because the CG was where some flight tests with the wings on another airframe had told me it should be..
I've repaired the wing, the rest is going to take some time. a new inverted-V tail wont take long, but to make the wings stand up more is going to be quite complicated, since the whole structure is build around a straight wingspar.. well, building is the best part anyhow!
Jun 23, 2012, 12:13 PM
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well, that didn't take too long..! I cut out the spar holder from the fuselage, and made a new one with a 15 angle. this brings the wingtips just above the birds centre of gravity. I guess that's what made it tumble upside down so easily, wingloading below the CG.... idiot me.
Jun 27, 2012, 06:24 AM
Registered User
This is the new body

since I had to cut away the old wingspar, AND wanted to embed the flight controller in the hull more to avoid that 'bulge' on it's back, the foam around the wingspar had seriously weakened. So i decided to make it carbon-reinforced..! I had ordered some carbon thread before, which is very strong but weighs virtually nothing. it litteraly floats in the air like spidersilk! I wrapped it around the spar and the body, and soaked it in superglue. That turned it into little rigid carbon rods.. feels quite strong now!

decide to do the same with the new tail:

I wanted to make it lighter then the previous tail, especially since the bird seemed 'tail heavy', but also stronger. so I used 2 mm depron sheets, instead of 3 mm which i used before, and applied the carbon thread reinforcements.

It came out weighing about the same, they are both around 4.5 grams. But the new one is stronger, and it definately looks better!

I had ordered some new servo's for the wings. they were supposed to have a lot more torque, as advertised on the HobbyKing website.
But when they arrived (very quickly, I must say!) the package mentioned somethnig else. So i decided to test them, just to see if they would be any use.
This is what it revealed...

As you can see the Turnigy 4.4 gr servo, which is advertised as having more than twice the amount of torque, is actually WEAKER than the Hobby King 3.7 gr servo..

I guess what I really need is these .. I have contaced HK and hope they are willing to change.. then I can finnish the wings and it will be time for TEST FLIGHT II.. fingers crossed!
Last edited by Johannez; Jun 27, 2012 at 03:37 PM.
Jun 27, 2012, 12:14 PM
Fear me, I'm a space-duck.
hanzie's Avatar
That's a lot of carbon...
Jun 28, 2012, 06:43 AM
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G-LO's Avatar
I think your wings need more dihedral.
Jul 02, 2012, 11:58 AM
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More dihedral, yes, that was the word i was looking for, thanks!

well, she's got more dihedral (about 15 more), she's got a new tail, she's got a carbon re-inforced body and lots of other minor improvements... but I'm still waiting for stronger servo's to build into the wings (No thanks to Hobby King, who send me weaker servo's...).

Beatiful weather today though.... hmmm
..Guess I really need to do some gliding tests!

glijvlucht (1 min 16 sec)
Jul 02, 2012, 01:09 PM
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Janusz Jawien's Avatar
Looks like you are now heading into the right direction !
This chicken is going to be a great flier!...:-)
Jul 02, 2012, 05:37 PM
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G-LO's Avatar
Woooow! That was great! Ill say she's ready ...
Jul 02, 2012, 07:18 PM
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Ken41's Avatar

Nice work, looks good now, keep up the great work!

Jul 12, 2012, 09:52 AM
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just thought of something today! very stupid that i didn't think of it before...

Since the CG had to move forward I put 20 grams of lead on the nose, and wrapped it in teflon tape. The CG's on the right spot now but the bird looks quite ridiculous. Like it's muzzled. I hate that..
When I changed the dihedral of the wings, there were some much connection things (like the magnets) allready build in the body, that I could not at the same time move the wings back a bit (instead of moving the CG forward)... I also hated that because I don't like having to ADD weight. but there was no other option. or so I THOUGHT...

Because today I realized I can also make the wings SWEEP BACK a few dergrees, just enough to make the wings' CG aligne with the body's CG!
...should have thought of that when I changed the dihedral. guess now I'll just have to cut the spar out of the wing, move it a few degrees and glue it back in!

At least it'll give me something to do, while im STILLLLLL waiting for those metal gear servo's to replace the wingtwisting thingy..!
Jul 12, 2012, 05:24 PM
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G-LO's Avatar
No Johanez! Don't cut the spar! If you want something to do, just make another set of wings. You have a masterpiece.... don't mess it up! Try to find another creative way to add weight. It don't have to look like a muzzle .

This may be weird but just get some heavy duty wire cutters and cut -longe ways- the lead weights; shape then, and apply. What do you think?
Jul 12, 2012, 06:11 PM
imyohero's Avatar
Amazing work!

I agree, your glide test looked great leave the wings as is, atleast until a test under power.

Keep up the good work! love it, Fantabulous lol
Jul 13, 2012, 12:42 AM
ancora imparo
jj604's Avatar
Johannez, that's an easy problem. Round here in the city every second seagull you see is snatching a chip (French Fry for the Americans). Model that for instant forward weight.


Originally Posted by Johannez
just thought of something today! very stupid that i didn't think of it before...

Since the CG had to move forward I put 20 grams of lead on the nose, and wrapped it in teflon tape. The CG's on the right spot now but the bird looks quite ridiculous. Like it's muzzled. I hate that..
Jul 13, 2012, 04:04 PM
Registered User
HAHA I like the idea of a chip in its beak..!

But seriously guys, I feel warmed by your pasionate pleas, but now Im hesitating again.. Sure I can find some creative way to hide the weight, but I just dont like the idea of 20 grams of extra added dead weight, when I've done everything I can to build it as light as possible..!

And I wont mess up the wings, I promise.
I can cut out the spar, stuff the hole with foam, sand it back to invisibillity, and then gently carve out a neat new groove using a dremel..

And the wings just needs to sweep back a few degrees. Without the weight, the CG is now like 1,5 cm off. that means (if my wet finger estimations are correct), when I turn the wingtips about 4 cm back, it's CG will be right on the spot. doing so the trailing edge of the wing will dig about 3 mm into the fuselage, and the leading edge will stay 3 mm clear of the fuselage. nothing that is not easily fixed..!

as for the looks; it will look pretty much the same. (The wings are actually slightly swept forward now, so i might just look even better!) It'll just be 20 grams lighter..

Another thing: I recieved my replacement ThunderPower 3S Lipo (last one had a bad cell), and I hooked it up today. The difference in thrust is simply AMAZING..!
With throttle at 1/3, it sounds and feels more or less the same like full throttle with the standard 2s lipo! and then you go up.. slowly.. more and more and more, it just wont stop! Full throttle with the 3S is like holding your own private hurricane! I let it blow in my face and I couldn't breath. It blew my kid away, too. literally! (she's 1,5..

So maybe you're right. lets just hook this baby up and watch it fly first.
Just STIIILLLLL waiting for Hobby King to deliver my new and improved metal gear micro power servo's...........

thanks guys!

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