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Sep 30, 2010, 09:35 PM
I Love My Ember!

My EPP Thumbwing


A few pictures of my nearly complete Thumbwing. Made entirely of 9mm 1.3# EPP. The weight without the control linkages or receiver, according to my old and not super accurate scale is somewhere in the area of 2.5 ounces. I made a little "canopy" out of PU glue (painted black) to cover the electronics bay, but am unsure of the method I'll be using to secure it.
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Sep 30, 2010, 09:59 PM
Registered User
j2m2t2's Avatar
Nice mikebergy. I would round the leading edge a little and maybe taper the trailing edge too.
Oct 01, 2010, 06:04 PM
I Love My Ember!
I thought about that, but it's a pain to sand EPP; I thought about doing it with a knife, but I may just skip it, as it is my first sloper, and as a novice glider pilot, it's unlikely I'll notice the performance increase until I've gained a bit of flight time.
Oct 03, 2010, 06:45 AM
DS will change your life
SpeedsterDEN's Avatar

DS demo


Flying my Alala,ish scratchbuild, in a Dsing demo.
Ballasted to 600 gram.
20 knots wind.



Scratch build foamie, DS demo. (2 min 6 sec)
Oct 03, 2010, 06:48 PM
I Love My Ember!
So I maidened her today. She flies ok, but I was never able to get her very high. Whenever I tried to SAL her, she did a loop on herself and was never able to retain altitude. As it got windier, I noticed she is way too light, as she was getting blown back quite a bit. Any tips on setup? CG is at ~30mm from the LE at the wing root - is that too far back? It also seemed that I needed a bit of up elevator to keep her flat and level.
Mar 01, 2011, 05:23 PM
Registered User

MY attempt at the alula clone


alula clone i built is a good bad thing.. hand launched it into the wind and it went up about 30 feet. so i desided to throttle it and see what happen. Nose heavy with three cell but balances where they suggest the cg... so hand launched it hard. up 50 + feet soaring the wings start to bounce .. yep it flys nose heavey. I bring it down. comes down kinda fast and hard but belly land and slides for good 20 yards
n3wdaddie: put 2 cell in it . motor is little loose now from hard landing. no vertical with 2 cell but i am trying into wind.. i get it up about 200 feet and glide it around. cant find a thermal but the wind is moving it around ( still nose heavey ).. i get about 15 feet of ground and hit throttle to go back up and it dont want to go up it wants to come down.. I cut throttle about 10 feet off ground try to turn into wind but it wont turn into wind ( not enough hight i guess ) wind catches back of folding prop and spins it just a bit as it gets to about 3 feet off ground and snap both blade break.
n3wdaddie: I get mad throw it in the air and it goes about 60 feet up and i glide it around till it is on the ground. grab it and put it in the truck and came home.. so It launches great ( hand launch )- still nose heavy- and needs a new prop. I think if i get the cg were it should be it will fly good. as for soaring. if i find a spot even with bouncy wings i think it do ok..
Motor is a 1700 kv blue wonder
batterys are all 500mah 2 and 3 cells
esc is 12amp ( pulls less then 10 amps )
prop is a 8x4 folding prop
Cant get pictures to post but here is the link to some on my face book. Not the best but you can see mostly what it came out like.
http://www.facebook.com/album.php?id...closeTheater=1
Thanks for looking
Bruce M
Mar 01, 2011, 06:24 PM
Registered User
davereap's Avatar
Alula and Weasel type clones are very popular..heres mine
https://www.rcgroups.com/forums/show....php?t=1391999
Its using a new KF profile the KFm9 .. steps at 35,50, 75%
built from 4x3mm layers of foam with a CF spar ..
The thin wing glides great.. 150ft distance from a 6ft height throw..
It has been catapult launched using 10M rubber bungee..I cant SAL worth a D*** ..best flight no lift about 48 secs...It also slopes well in very light winds
Jan 22, 2014, 07:23 AM
David the Swarfer

my Thumbwing


I finished this one last night. KFM2 with 9mm EPS foam. Leading edges and wing tips have laminating film (dunno how thick, from an A3 sheet that was next to the office laminator) and there is a 6mm carbon spar in the middle.
After the lam film I covered all bare foam in clear tape, then applied the color tape.
Tail is 4mm posterboard with lightening holes. Battery is 4 AA NiMH. AR6110 receiver and 2 5gram HTX servos. Hinge lines are fibre reinforced tape.
Sep 05, 2018, 10:46 AM
Registered User

Lidl-Alula (OR NOT!)


Hi all - so I've recently started scratch building planks after seeing the success of the Lidl XL glider. After seeing this thread and the A-Clone builds in Dave Reap's KF thread I decided to give one a go. Anyway - I had the idea to try the build with a 'real' foil and, having a spare Lidl XL wing on hand - decided to see if I could convert/ reshape the wing into a forward sweeping Alula-like version.

I realize there is little wrong with KF steps or the RM wing but wanted to try this in the hope of having something worthwhile to share with the community.

Fast forward a week and I have:

Sliced the wing in two span-wise
Inserted a triangular section in-between the wing halves to give it the forward sweep
Added 4mm CF spar
Added scrap EPP to create the wing tips and extra span (at the TE)
Glassed the whole wing with PU and super-light glass cloth
Added balsa elevons
I also added a tiny amount of light wood filler here and there to finish
Covered in tape.
Built the fuse with motor mount.

Now - I set the CG as suggested (3 inches from leading edge) and it takes an almighty weight to balance it!!! So, as anyone reading this will have guessed - it flies like (probably worse than) a brick! Gutted! Especially since its my best looking build yet.

So - can anyone help me assess if this is at all flyable and perhaps just need to find the correct CG or - will the wing be too heavy at > 200g (thick EPP + glass)?
Now I've changed the angle of the foil from front-back to front-diagonal back will that make a key difference?
Shall I just strip it and bin it?

Weights:
Wing with servos = 252g
Fuz = 37g
Rx = 4.7g
ESC = 34g
So without battery ~327g
AUW with 3S 800mAh ~392g

cheers Craig

P.S The white strips on the wing are where I've attempted to raise the level/ blend in the scraps of the EPP before sanding down to a sliver.
Last edited by craigjell; Sep 05, 2018 at 04:26 PM. Reason: Added weights
Sep 12, 2018, 01:45 PM
Flying Half Pound and Down
DaOldGuy's Avatar
You may want to do the math on the wing loading, it may be a brick 8) Some wing styles, even more so with a performance wing, don't fair well with weight.

The Alula Tek Specs
WINGSPAN 900 mm (35.4 in)
WING AREA 16.71 dm2 (259 in2)
*WEIGHT 156-184 gm (5.5-6.5 oz)
*WING LOADING 9.3-11 gm/dm2 (3.1-3.6 oz/ft2)
Sep 12, 2018, 09:08 PM
Registered User
How can a 21 st century ESC.. for ~ 800 mah battery power.. weigh 34 gms ?
Sep 15, 2018, 06:42 PM
Quad Erat Demonstrandum
scousethief's Avatar
Quote:
Originally Posted by craigjell
Hi all - so I've recently started scratch building planks after seeing the success of the Lidl XL glider. After seeing this thread and the A-Clone builds in Dave Reap's KF thread I decided to give one a go. Anyway - I had the idea to try the build with a 'real' foil and, having a spare Lidl XL wing on hand - decided to see if I could convert/ reshape the wing into a forward sweeping Alula-like version.

I realize there is little wrong with KF steps or the RM wing but wanted to try this in the hope of having something worthwhile to share with the community.

Fast forward a week and I have:

Sliced the wing in two span-wise
Inserted a triangular section in-between the wing halves to give it the forward sweep
Added 4mm CF spar
Added scrap EPP to create the wing tips and extra span (at the TE)
Glassed the whole wing with PU and super-light glass cloth
Added balsa elevons
I also added a tiny amount of light wood filler here and there to finish
Covered in tape.
Built the fuse with motor mount.

Now - I set the CG as suggested (3 inches from leading edge) and it takes an almighty weight to balance it!!! So, as anyone reading this will have guessed - it flies like (probably worse than) a brick! Gutted! Especially since its my best looking build yet.

So - can anyone help me assess if this is at all flyable and perhaps just need to find the correct CG or - will the wing be too heavy at > 200g (thick EPP + glass)?
Now I've changed the angle of the foil from front-back to front-diagonal back will that make a key difference?
Shall I just strip it and bin it?

Weights:
Wing with servos = 252g
Fuz = 37g
Rx = 4.7g
ESC = 34g
So without battery ~327g
AUW with 3S 800mAh ~392g

cheers Craig

P.S The white strips on the wing are where I've attempted to raise the level/ blend in the scraps of the EPP before sanding down to a sliver.
Give it some nose weight and throw it ! If you can get a decent glide out of it then pursue it.
Sep 16, 2018, 12:33 PM
Registered User

A lot better


Well - it was definitely overweight so I decided to see just how much I could lose.

Cut lightening holes in the wing
Replaced the balsa elevons with depron.
Removed all the WBPU + glass cloth
Removed packing tape
Replaced the Align DS410 with HXT500
Removed the ESC
Removed the 3S 800mAh pack

Added a 4xAAA pack and switch
Covered in monocote
Switched to the Lidl XL fuse as its got a really long nose.
AUW is now - 273g so a loss of 119g!

I've done a few glide tests now and it really does glide quite nicely (IMO) and seems fairly robust. Some lessons learned here for sure


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