edit after a lot of messing about I gave up on the twin diferential motors...the airfame design however is very good ..strong and stable but please stick one larger motor on it, not the two

Goolies.
http://www.rcgroups.com/forums/showthread.php?t=990577
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A few comments mentioned that it looks very much like a superfly
Take a good look and tell me what you think...isnt that nearly the superfly shape.. have a read, its a great idea they have had..and the epp foam kit is not too expensive..
But for those who want to make their own I have modded the superfly clone and renamed it the CYCLONE

Working from the superfly drawings it didnt take long to reshape the elevons and make two prop slots instead of the one... Adding a centre Fuz top and bottom and some lower fins finishes the job...

I have repositioned the slots to fit behind the KF steps, but if you do away with the steps and use a CF flat reinforcement along the curved line you can move the slots more forward and that will make it easier to get the correct cog..

Keep it light and two of the 1300 or 1500 BW motors will do nicely.. props apc push and pull 7x5... note apc do push/pulls in other sizes so you can go bigger or smaller
top and bottom fuz and fins can be shaped much as you like.. my shape as a guide only

I have included the Sketchup file as then you can rescale to suit your requirements

Ive started on the moddified superfly/goolish cross.. here are the lines, and so far ive cut the main layers all in 3mm depron..
Note the span on my model has been raised to 30".. this is because I think my build will end up slightly heavier than the stock Goolie. I wanted a touch more area (now at just under 3 sqft) in order to get as low a wing loading as possible for the best slow flight..
I am going KFm4 again, but the step positions are altered to get the slots forward to help achieve the COG..
Remember KFm4 is a step on top and an identical step on the bottom. See the earlier superfly construction for general methods..
On this build there is no additional depron spacer between the layers, just a 3/4x1/4" balsa spar at the step line
Ive made further modifications from my sketchup drawing..
I am not going with an upper fuz, but I will have top and bottom fins in 6mm depron, and an enlarged lower fuz..in 2 layers of 6mm depron.
In my normal fashion I will leave the top clear for the multiple velco strips I use for fixing the battery etc.

edit... Increasing the size to a 30" span was a good move the final AUW is 13.5oz with a 1250 3cell lipo.. this is 4.3oz sqft ...the 28" goolie was 4.4oz sqft

edit....I measured it incorrectly after a lot of flying ive noticed a mistake in my build..how I missed it I dont know..I measured wrong...the sweep back on my version was only 12" instead of 14 5/8" and as a cosequence the COG ended up at 7.5 back from the nose....However it flies a treat so the moded lines are now below....A new shape

Originally Posted by davereap

Ive started on the moddified superfly/goolish cross.. here are the lines, and so far ive cut the main layers all in 3mm depron
I am going KFm4 again, but the step positions are altered to get the slots forward to help achieve the COG
I am not going with an upper fuz, but I will have top and bottom fins in 6mm depron, and an enlarged lower fuz..in 2 layers of 6mm depron.

aWESOME BUILD dAVE GOTTA HAVE IT.

The build has progressed...a similar build to the superfly at the begining of this thread. but note the distance between the LE glued areas and the steps is small so..no depron spacer/spar is needed
One silly mistake ive just noticed, for lots of extra strength I should have taped along the wing before I fixed the fuz and fins..still its supposed to be light weight so stresses should be minimal.. time will tell..I might yet remove the fuz so I can tape across the centre section, then replace the fuz, if it comes off easily
edit...the fuz was too well fixed to remove so the taping was only made on the exposed surfaces

a few years ago i made a huge super fly out of bluecor. it was about 2-2.5 times bigger. was pretty cool. i wish i had some pics of it

The Superfly shape makes for an excellent delta , the kit versions are well worth buying.
However using the KFm4 section or a KFm2 with the superfly shape gives a low cost alternative, which flies excellently. It is also a quick build..
With the superfly the original size has always been the most liked, that was about 27" span.
The Goolie is produced at 28"
The CYCLONE is 30"

Ive now mounted the motor mounts..
Ive use the tube type.. first I cut them down to fit against the step.

Then I use a drill to extend the line, and after lining them up with pre marked thrust lines, I fixed them in place with cool melt adhesive

The mounts are locked in place with multiple depron strips, using uhu and cool melt to gap fill.. and when fully blocked in the block is rounded off.

Lastly cutouts are made for the motor, and to get at the mounts fixing screws

Been taping up and fitting the elevons and gear..Taping over depron is well worthwhile, it adds more strength than you would think, and makes depron much stiffer when the tape is on both sides..I always fully cover my elevons etc with this tape and reinforce all the areas that can be seen in these pictures...
Without the tape depron will tear in an impact..with tape not much damage


Only the control rods and REC remain to fit

The AUW will be 13.5 oz with a 1250 lipo ..so its 4.3oz sqft ....the 28" Goolie comes in at 4.4 oz sqft...so I have done this ok so far

Notes on other parts.

Fuz and Fins...
The central lower Fuz is made from 2x laminated 3" wide lengths of 6mm depron... Fitting requires some cutting out, to seat the front of the fuz against the slope of the outer layer.. the rear of the fuz behind the step fits flat, so is no problem.. The front of the fuz is shaped round and the rear is tapered down to about 1.25" depth at the back..
The lower fins are cut from 6mm depron one layer thick and are also 3" in height, cut to length for the location of fitting.. again they need fitting over the slope at the front, and the rear portion glues flat.. again shape as you like... When fuz and fins are fitted the plane sits on all three bits nice and level
The top fins I made deeper at 4" with a more swept back look. Fitting on the opposite side of the wing.
Make sure they are all vertical and line up nice and parallel to the planes centre line..

Motors and props.
I have a couple of the 1300 kv BW motors so I will try them with 8x4 gws props on 3 cells...
Theres a possiblilty that counter rotating props are needed, so 7x5 APC are available if needed

ESC 2x 12A cheapos
Servos 2x 9gm DYS or tower pro

REC... corona 2.4 4ch units...only 3gm and they work so well

Ive almost finished now, its all working... except I was struggling on the programming ...so a read on the goolie thread informs me I should be using 2 mixes on my futaba, and this would explain the odd results I have been getting with the motors..so I still have the second mix to program in
NOTE
One thing you do need to do, is to get the motors running at the same revs when you use different throttle settings....even the same make and kv motors vary a bit... I was using 2 1300kv BW motors and one consistantly turned over faster...I could trim at individual throttle settings, but when I moved the throttle it always needed retrimming... no good... the solution was to trim a tiny amount off the slow motors prop, only 1/8 off each side was needed to get the slow motor up to the same revs, and when I changed the throttle setting the motors stayed almost together..not enough now to worry about

Edit...sussed the problems with the programming for a ff9c use +100/+100 throttle to rudder ...-70/-70 rudder to throttle ... program mixes both on... note there is a link option, turn it off

Recap on the specs
KFm4 wing all in 3mm Depron..each step is 9mm deep (1/4+3mm).. Balsa spars 1/4x3/4..
span 30"..AUW with a 1250 lipo is 13.5oz..wing loading 4.3oz sqft..
motors BW 1300kv.. props gws 8x4..Thrust available 26oz+
servos 2x - DYS 9gm
esc any cheapo 10-12A
rec Corona 2.4Ghz 4ch
Having 26oz thrust this thing is well overpowered

I have been doing a little building with depron and used 3M 77 for glue but it does not seem to continue to hold. What is the u hou glue or what ever you mentioned using?

The best general glue for depron is Uhu POR, its a contact adhesive, spread a thin layer on two surfaces wait till its dry and press together...be warned it sticks well so make sure your positioning is accurate...
other glues ..epoxy... good for solid fixing but it can add weight
cool melt adhesive... the low temp one is just ok on depron ...again it can add weight.
CA foam safe.. works but I get on better using mostly the UHU POR

Have a care...other glues can melt the depron
oh and dont forget sticky tapes are also useful,

Ive finally got the motors running as they should, the programming is a bit weird..
using two mixes
On a FF9 mix 1 throttle to rudder is +100/100 but, if on the mix 2 rudder to throttle I use -100/-100 it doesnt work..however going down to -70/-70 or -50/-50 it then does
note + and - settings they are important

The CYCLONE has flown.. this is the renamed superfly/goolie crossbreed. using a KFm4 wing
here is the video..
there are problems but, not with the airframe..they are with getting the motors running equal as you power up...watch what happens as I throttle up..
Luckily at 1/4 throttle all was in ballance, and it was flying well..
It certainly rotates when you use the rudder to vary each motors speed, it made me laugh
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Cyclone (3 min 1 sec)

edit.. after another tune up another flight, and the same problem shows up. increase the throtle and it does a nice right turn ,,you can hold left rudder whist doing that but its a pain..
other problems ....Hand launch shows bad torqe rolling.....with two props it glides like a brick...after the glide giving up throttle gives a bad torque rolling movement and the motor problems make it worse throwing the line off
what is nice is the differential motor control, its much more effective than just a rudder...with half power, half up elevator and full rudder the cyclone rotates like a loony and only slowly comes down...
And the power to weight ratio lets it go up like a rocket
If I can sort the motor problems it will be great... If I cant..well I dont know

To start with a couple of counter rotating props will help, and may be two new motors so they come from the same batch

edit all now sorted

Originally Posted by davereap

...
there are problems but, not with the airframe..they are with getting the motors running equal as you power up...watch what happens as I throttle up..
...
edit.. after another tune up another flight, and the same problem shows up. increase the throtle and it does a nice right turn ,,you can hold left rudder whist doing that but its a pain..
...

One possibility for dealing with uneven motors is to use what the heli folks use:
a gyro to help tame yaw.
Gyros can get expensive, unfortunately (a good head-holding gyro can cost as much as the rest of a foamy and gear).