Alula in Foamboard
- Thread starter Hai-Lee
- Start date
Michael9865
Elite member
It looks great.
bracesport
Legendary member
Hai-Lee
Old and Bold RC PILOT
Definitely able to be scaled though you would need to use the 5 mm FB as apart from the wing spar the entire structure is hollow and relies on the rigidity of the FB for its overall strength.
No paper on any internal surface. When scaling up you may find that you are able to get a relatively lighter build, (lower wing loading and of course higher lift due to the change in Reynolds number).
Sadly not a real speed bird when sloping due to the light weight BUT it should be a fun and nice bird when the wind is light!
Will let you know how it goes with the maiden, (this weekend - weather permitting).
Have fun!
bracesport
Legendary member
at least we can buy those larger sheets of FB here! looking forward to the maiden!
Hai-Lee
Old and Bold RC PILOT
Just a heads up though! If you follow my design/build technique you need to know that you may need a lot of sandpaper.
The wing lower panels taper to paper only at the wing tips and the wing hinge line.
The curved portion of each wing's LE is sanded/shaved from around 1/2 mm down to zero at the wing tip end. I use a glue, poke and tape technique to get a curved extension of the fold type LE.
The wing is scraped as per Master series to get the rough shape BUT very little at the tips and more are the wing root. I managed to get a little reflex but I would like more so the next version may have the Elevons included as part of the lower wing piece to see if I can increase the reflex angle.
As the Spars are slightly angled with respect to each other, (the wing has a forward sweep), A "BENT" dihedral brace is used albeit only a simple wooden brace type as the wooden spars glue together really well and with considerable strength.
The servos are mounted directly behind the wing spars, (I used hot glue to fix the servos in position), as far outboard as their wires would allow whilst still being able to connect to the Rx mounted under the wing LE.
As I use a dual antenna radio system my antenna leads are run out of the nose section centrally at the underneath rear portion of the nose where it glues to the wing surface. From here they assume their required 90 degree angle along the under surface of the wing each antenna pointing at 45 degrees rearwards.
Finding the exact CG point will be the first task as I do not have an Alula to measure and the manual uses a few landmarks rather than a measurement from the LE of the wing.
Busy sealing and getting for a shot of colour!
Have fun!
Hai-Lee
Old and Bold RC PILOT
I do have a bit of a cheat as I have a "Dancing Wings Lighting" to maiden as well, (as a glider), and it has a similar planform.
I know precisely where its CG is required to be and so I may be able to get close with an educated guess on the Alula. From there it is just a matter of making minor adjustments based upon its flight performance!
Have fun!
Hai-Lee
Old and Bold RC PILOT
Well it did glide but only at the very slowest of speeds. a Hefty throw saw it rear up and then stall followed by either a glide or a nose first crash.
Effectively wrote off the nose which has since been replaced. Post test analysis showed a few issues with the setup choices.
1. I used the client supplied control horns. They would not stay locked to the elevon. This lead to not having consistent elevon deflection or even operation. Caused many crashes in isolation or by themselves.
2. The servos might be too weak and uneven in operation. Damn Cheap Plastic servos!
3. Because of the above I was unable to obtain any real useful flight test date BUT the glides at minimum speed were very slow indeed.
4. This fault is all mine as the Chosen CG point was way too rearwards. Revised the starting balance point for the next series of tests and am building a second version with a slightly thinner wing root section and a spar reduced in thickness to 3mm, (Balsa).
Pics later when the second version is painted and ready for testing.
Have fun!
Effectively wrote off the nose which has since been replaced. Post test analysis showed a few issues with the setup choices.
1. I used the client supplied control horns. They would not stay locked to the elevon. This lead to not having consistent elevon deflection or even operation. Caused many crashes in isolation or by themselves.
2. The servos might be too weak and uneven in operation. Damn Cheap Plastic servos!
3. Because of the above I was unable to obtain any real useful flight test date BUT the glides at minimum speed were very slow indeed.
4. This fault is all mine as the Chosen CG point was way too rearwards. Revised the starting balance point for the next series of tests and am building a second version with a slightly thinner wing root section and a spar reduced in thickness to 3mm, (Balsa).
Pics later when the second version is painted and ready for testing.
Have fun!
Last edited:
bracesport
Legendary member
Hai-Lee
Old and Bold RC PILOT
Yes the original had a wingspan of 900mm. Seriously though, once you have the wing shape and profile you want scaling the whole thing is so very easy!
FYI the second version, (pink), is actually noticeably lighter than the first! It looks like I might have cracked the weight issue!
Have fun!
Michael9865
Elite member
Those look great.
Hai-Lee
Old and Bold RC PILOT
Just a little bit of info that might help others to obtain that finer LE, (especially on curved LE sections).
For the curved wing tips of the FB Alula clone I was looking for a simple method to go from the standard beveled Straight LE to the single FB thickness wing tip section. What I ended up doing was to bevel and sand the inside surface of the join so that the upper and lower panels met on the curved section and were only a single FB thickness, (or slightly less), when held together.
Now here I got a little creative! I noticed that the cheap office sticky tape would barely stick to the paper on the FB and would not stick to the liquid glue I use. It was also somewhat easy to remove from the glue when the glue dried under the tape. So i applied a little liquid glue onto the reduced thickness FB at the curved LE and used the tape to "Stitch" the curved LE down and to the required LE profile.
I would stick one end of a piece of tape to the upper surface of the LE and using a steady pressure I would wrap the tape around the LE and adhere it to the under side of the wing. Where the LE material was not crushing or tucking under in the manner I wanted I use a paddle pop stick or a BBQ skewer to "Tuck" the material into the wing and so allow the paper edges to come into contact.
After doing multiple overlapping tape stitches I would allow the glue to dry. When dry I would remove the tape and then I had a continuous LE shape from the wing root to wherever I stopped the stitching .
MUCH, MUCH, better than the blunt edge of the cut FB, and easier, (less mistakes), than ironing. With a little practice and the right glue you can even embed BBQ skewers, wire, or the like into the LE so that it cannot be seen. Even without embedded reinforcement the "Stitched" LE is considerably stronger, being reinforced by a line of dried glue.
My next extension of the use of the "Stitching" will be to attempt a truly sculpted Fuselage, (compound curves), on another model. This design is about to enter limited manufacture, (I have a number of pilots from interstate that are seeking their own copies).
Anyway, it works for me!
Have fun!
For the curved wing tips of the FB Alula clone I was looking for a simple method to go from the standard beveled Straight LE to the single FB thickness wing tip section. What I ended up doing was to bevel and sand the inside surface of the join so that the upper and lower panels met on the curved section and were only a single FB thickness, (or slightly less), when held together.
Now here I got a little creative! I noticed that the cheap office sticky tape would barely stick to the paper on the FB and would not stick to the liquid glue I use. It was also somewhat easy to remove from the glue when the glue dried under the tape. So i applied a little liquid glue onto the reduced thickness FB at the curved LE and used the tape to "Stitch" the curved LE down and to the required LE profile.
I would stick one end of a piece of tape to the upper surface of the LE and using a steady pressure I would wrap the tape around the LE and adhere it to the under side of the wing. Where the LE material was not crushing or tucking under in the manner I wanted I use a paddle pop stick or a BBQ skewer to "Tuck" the material into the wing and so allow the paper edges to come into contact.
After doing multiple overlapping tape stitches I would allow the glue to dry. When dry I would remove the tape and then I had a continuous LE shape from the wing root to wherever I stopped the stitching .
MUCH, MUCH, better than the blunt edge of the cut FB, and easier, (less mistakes), than ironing. With a little practice and the right glue you can even embed BBQ skewers, wire, or the like into the LE so that it cannot be seen. Even without embedded reinforcement the "Stitched" LE is considerably stronger, being reinforced by a line of dried glue.
My next extension of the use of the "Stitching" will be to attempt a truly sculpted Fuselage, (compound curves), on another model. This design is about to enter limited manufacture, (I have a number of pilots from interstate that are seeking their own copies).
Anyway, it works for me!
Have fun!
Hai-Lee
Old and Bold RC PILOT
Tomorrow is the big day to hopefully get the birds flying. I managed to track down an actual CG point that is measured from the LE and the measurement confirmed my experiences. I had been using just under 50mm whereas the CG point should be around 25mm. No wonder it wanted to pitch nose up at all but the slowest of speeds and considering the Reflex setting I was using it was close to maximum up under the current settings.
As I stated, tomorrow is the big day. If they fly I will have to get to work as the orders must be delivered to the other side of Australia before Christmas!
More later.
Have fun!
As I stated, tomorrow is the big day. If they fly I will have to get to work as the orders must be delivered to the other side of Australia before Christmas!
More later.
Have fun!
Grifflyer
WWII fanatic
If it works, I would like to try building it with DTFB!!
Hai-Lee
Old and Bold RC PILOT
Firstly there are to be 2 versions. The first is as described above, (3 mm FB), and will be the Kulula, (Named after the owner - Ku and of course the Alula which inspired it) and the other is to be in 5 mm FB and around 1400 mm wing span which will be the Kelula, (Kel is the owner and the Alula of course).
As for flying they both did and the balance is a tad more than 25mm back from the wing LE where it glues to the nose/fuselage. Took them both out today when the wind was blowing quite strongly at times but direction was a little erratic. Also managed to use the bungee for a few launches, (around 10), and the speed and climb were surprising but the weight was a little too light for the conditions.
The earlier version with the thick wing did fly OK but not as well as the thinner wing version so the thinner wing version will be the one subject to plans being drawn up!
Ended up nosing the Kulula into the ground about 5 times, (often at high speed), before the nose was finally destroyed. My fears about the wing strength were answered when one launch ended up with a roll and a high NEGATIVE "G" loop which launched the ballast weight, (Out through the hatch), way beyond the flying area boundary into the bush where it remains. Even flew with an additional 60 grams of lead ballast to improve penetration and whilst it did sink a little quicker it still flew quite well.
So now I have to make 4 Kulula, (1 with motor power), and 3 Kelula, (1 with motor power). Sadly if I want one I had better add it to the list soon!
Based upon today's efforts I may be adding a little additional reinforcement to the nose area BUT the wing spar, (even using 3 mm Balsa) is way stronger than required and so a FB spar should suffice!
Just one note of warning! The bird can be very pitch sensitive due to the light weight and the massive elevon area. It was still flying and fully controllable at less than walking pace when the wind died away!
In addition the LIGHTING which is a similar but retail offering also flew but it could not handle the conditions anywhere near as well and it definitely could not survive any more than 2 nose in landings. Actually it made the Kulula look way superior in all aspects!
Anyway that is all I have to report except that i will now go and build a new nose for the Kulula and perform yet another repair on the Lighting!
Have fun!
Hai-Lee
Old and Bold RC PILOT
I have to finish Half of the builds well before then.
Just been looking at the scale for the Kelula and I think that 1.2 Metre wingspan, (4/3), is a good compromise but will still be using 5 mm FB for the plans. In addition I will be adding a paper clip hatch lock on the top of the fuselage for battery access.
Have fun!
Grifflyer
WWII fanatic
Would 5g servos work for the 1.2? I have 9g servos, but my 5g's are higher quality.
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