24" span SU27/Eagle/f22 trio - Page 11 - RC Groups
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Sep 16, 2012, 05:18 PM
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I built one of these a couple weeks ago (26") and have really enjoyed it. I put a 370 class "speed" motor in it and it is exactly the perfect "first" slot jet for me to learn with. Having a blast with it. thanks.
Last edited by jim2wright; Sep 16, 2012 at 05:28 PM.
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Sep 21, 2012, 04:56 AM
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Note the modded small version is to be scrapped.. whist it flies, the original open build was far better... so dont do a fully enclosed small version ..its not worth it..

next will be a smaller version.. going to downsize for convenience...
Last edited by davereap; Sep 22, 2012 at 03:20 AM.
Dec 08, 2012, 02:22 AM
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Going back to the origin for this set of models I have been doing a sketchup drawing of the Ikarus SU27.. the first 3mm model propjet that used the brushed motor and a tiny prop..
despite its drawbacks the basics were good enough to have a follow up with bigger size models..xxl..
The small original was too limited in that it was designed for a tiny motor and prop..It was let down by this and its long fragile nose..

So you can see why my first model was made both larger and out of scale in width...I wanted mine to take an 8" prop in the slot..
If you go onlne the building instructions pdf can be found easy enough.. it is too big a file to post here..

I am planning to use the sketchup drawing to reshape the model for indoor flying with a 5gm brushless motor using a 5x3 prop..by carefull selection of parts, I can first widen it up then shorten the nose

Its still being worked on... I only want to use a 5" prop so I must move those sides in some more
Last edited by davereap; Dec 08, 2012 at 05:18 AM.
Dec 08, 2012, 03:20 AM
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moved the sides in.. and that looks better..its enlarged the ailerons again
the elevator sections were adjusted, so now the full length lower fuz is possible.

The vertical nose section is scaled lengthwise, but now the tabs will need shifting along..
By the use of construction lines the tabs were aligned and small corrections made where they were a bit over size..now its a good fit...
The fuz will go back to the motor position , likely it will need trimming to sit against whatever block I make for the motor mount..

after more work I pulled out the parts and set them up for printing... see the pdf in the next post... with a bit of luck it should all fit together ..
Last edited by davereap; Dec 23, 2012 at 05:20 AM.
Feb 23, 2013, 10:01 AM
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Ive just started putting the gear in this one....
After messing about with micro blocks I think a better option is the orange 2.4 micro rx with 3x2gm servos, a 6A esc with a 5gm motor..on 2 cells I can run a 6x3 prop with tips cut down by 1/8 to better fit my slot.. and use a 160 -300 2 cell..

control surfaces are hinged using uhu por, the tiniest bead is put along a chamfered top edge ..this makes a strong fix and a flexible almost invisible hinge..

rx.. http://www.hobbyking.com/hobbyking/s..._Receiver.html
servos.. http://www.hobbyking.com/hobbyking/s...g_0_08sec.html
esc.. http://www.hobbyking.com/hobbyking/s...ontroller.html
and nano-tech batteries.. http://www.hobbyking.com/hobbyking/s...Lipo_Pack.html

The tiny servos are more suited for lower single cell voltages, so an 1n400x diode is soldered into the red wire on the servo lead with the bar pointing to the rx...this lowers the volts to something under 4v
Last edited by davereap; Feb 23, 2013 at 10:13 AM.
Feb 23, 2013, 05:06 PM
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24" Trio

There must be a servo that will fit the need without the extra weight of diodes. I do realize the diodes don't weight much.
Latest blog entry: Center of Gravity - Airplanes
Feb 24, 2013, 07:35 AM
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There are other servos but these tiny ones do work well, and whist I am changing the plug on the ESC lead to fit the micro rx sockets, I do the diode..
Its all a muddle with the micro plugs and sockets... 3 different micro sized types are used on different servos and rx units..
Then there are the standard ones used on most servos
I am reducing that to two.. the SH 1.0 mm and the 1.25 mm micro jst type for my smaller indoor models..
The orange rx uses the 1.25 and the ar6400 and supermicro uses the 1.0mm.. if I remember correctly
Feb 24, 2013, 07:41 AM
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I really like the way the small version looks, so I have drawn up a bigger KFm4 version
The idea is to use the same motor setup as I used in my Mako build... this is a high KV motor with a 6" prop ...it goes very well
one of these... http://www.giantshark.co.uk/221206-2...-p-402397.html

still to decide is whether to extend the KF on one layer right up to the nose, for better strength
note the top outer KF layer was taken all the way to the nose
The lower layer was left at the shape of the pink triangles on the lines..
All the verticals were made from 2x6mm depron except for the fins which are a single thickness.
Last edited by davereap; Mar 05, 2013 at 04:21 AM.
Feb 24, 2013, 08:55 AM
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On the mini su37, that thought I had about extra strength made me add a 3mm top layer to make a KFm2 wing.. it also doubles up the front and will make the nose be a lot stronger...the weight of the mini as now is 59gms with out a battery..

next some decor
Feb 26, 2013, 03:02 AM
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I must admit to liking the propjet models, and you can go with a simpler profile job or a sorta scale, right up to full scale.. they all go well... and with KFm2 or 4 they are great..

Yesterday I scrapped an older tatty F22 and started building the bigger SU37 I recently drew up..
For size I reduced the wingspan to the width of my depron sheet.. 27.5".. 690mm
The main center layer was cut in one piece , going down from the nose to the aileron hinge line , the top outer layer which includes the nose goes back to the step line and was cut in two halves, cut down the center line.. all the vertical splines and fuzz parts are made from doubled up 6mm.. The lower step is a simple small layer which lines up with the leading edge and the step locations..(a swept back triangle)..
I put one CF spar in the wing lined up across the rear of the cutout for the motor..this was more to flatten my depron which was a bit curved on the sheet than for strength..
I started the build by fitting the spar..laminating the lower outer layer and fitting the lower fuzz parts. I went from there to laminating the top layer halves and fitting the fuzz top

still to do ..the ailerons , elevons , fins and rudders....then to fit the gear...
I am also deciding whether to fit the motor high enough so the prop can be kept inside the fuzz at the bottom, and at the same time fit some partialy hidden wheels at the front to make it capable for ground take offs... The Big F22 is setup like that and it works well..
Feb 27, 2013, 04:15 AM
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span 27.5".. the width of my depron
motor 2212-06 2200kv with a 6x4 prop..
servos metal gear MG9 ..or similar ..
30A cheapo ESC..
Orange DSM2 RX
2200 20C 3s lipo
the elevons ailerons etc are all fitted and the gear is starting to go in
motor link.. http://www.giantshark.co.uk/221206-2...-p-402397.html
It is ballistic with this motor but only needs a fraction of the available power for cruising on
Last edited by davereap; Apr 03, 2013 at 03:42 AM.
Mar 03, 2013, 07:26 AM
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I finished its decor and programed the controlls yesterday
So I got to maiden my SU37 today..but unfortunately I forgot to get my gear and batteries all charged.. so, the two flights on its maiden were very short...
However they were long enough to say its perfect...
COG spot on .. power ... slow flight great.. twin rudder turns lovely...
I am going to really enjoy this one...

note the ailerons and elevons are all linked like the method used on the icarus SU27.... so for elevator all 4 will go up together and down together..for ailerons obviously both on one side go up while both go down on the other side
The twin ruddershave a cross bar to link them

All the controlls were very effective .. On the maiden I used the mid settings I had pre programmed for both elevator and ailerons, so now I will have to set those as my low rates and reset my up rates to some other %ages..
The rudders are at 100% for all rates
Expo was set at 30% for all settings
Rudder turns were made when the power had dropped.. Rudder worked a real treat in getting the nose to come round at the low speed

the short flights
SU37 KFm4 propjet short maiden flight (1 min 49 sec)
Last edited by davereap; Mar 03, 2013 at 07:44 AM.
Mar 03, 2013, 09:08 AM
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Nice Dave, very nice.

great work.

Mar 03, 2013, 02:22 PM
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The AUW with a 1300 lipo is 19.5oz
That gives me 6.8ozsqft.... which is more than I would have thought, just looking at the superb way it can slowly float along
Now using 2200 3S lipos which produce more power and a wing loading of 7+ ozsqft..
Now it goes superbly
Last edited by davereap; Apr 03, 2013 at 03:43 AM.

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