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Hobby King SunBird Motorized Glider Build Thread

#41
I just got my HK Sunbird kit. I'll be building this over the winter. Maybe not ALL winter, it shouldn't take that long. The last balsa airplane I built was about 45 years ago, a one channel 74" Lil'-T sailplane kit by Midwest. Flite Test got me back into this hobby with cheap, easy to build foam board. Now it's time to get Old School again. Joker's detailed build should help me avoid the unforeseen issues with this kit. Appreciate it.

I'm surprised by the weight of this bird. All the builds I've seen are much heavier than I expected. About 450 grams or more. Upon examining the kit I shouldn't be that surprised. The balsa is thicker than I expected and there's a lot of plywood parts. I'll probably cut lightening holes where appropriate and use CA glue as much as possible to keep the weight down.

Jon
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#42
Jon, all things considered the design and layout of the SunBird isn't *horrible*, although there are certainly things that could have been done better. The first change I'd absolutely make is to use a carbon fiber tube for the leading edge of the wing. The hard-ish wood sticks I got with mine were garbage. The wing is the hardest part to build and the ribs aren't labeled accurately (if I remember correctly), so I put all the ribs on the table and sorted them by number. Once sorted, half of each type went for the left wing and half for the right. Then it was a matter of trying to figure out which order they were installed. Some were obvious and others not-so-much. But doing it this way means you'll have enough ribs to do each wing the same. I think the wing is also meant to be built as a 2-piece wing, although it's not huge and if you've got room to transport it as a single piece it'll be better in the long run. Also, I think the details for mounting the wing were pretty weak, so as you're building the wing and fuselage try and decide how you want to put those two together and incorporate that into your build.

Post your findings! :)
 
#43
Thanks for the encouragement, Joker. I'd have to order the CF tubing. I think you used 3mm OD, right? In hindsight would you go 4mm?

I've watched several YouTube videos featuring the Sunbird. Lots of people have built them. Many of said Sunbirds have little or no polyhedral. For more lift and maximum advantage of the ailerons I'm assuming. With that in mind I think I'll make the center section flat and only add dihedral to the tip sections. What is the combined length of your two center sections (ignoring the tips)? I may be able to buy from LHS one length of CF long enough for a flat center section LE and use the supplied wood for LE tips.

I plan to attach the wing to the fuse with two nylon screws into blind nuts.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#44
Actually, I'm pretty sure I used 4mm CF for this build. I'm also fairly sure I used two sections of CF and cut them to length as needed since 1 piece wasn't quite enough.
 
#45
Hi guys!!!.

Today bought the Sunbird Electric Glider Laser Cut Balsa Kit 1600mm (Kit) from HobbyKing.

Looking forward to start my first built.



29302-2 (1).jpg 29302-1.jpg
 
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#46
Hi guys!!!.

Today bought the Sunbird Electric Glider Laser Cut Balsa Kit 1600mm (Kit) from HobbyKing.

Looking forward to start my first built.
Pay close attention to Joker's advice, especially where the wing sections join. The kit instructions don't tell you how to join the wing sections. Ribs have to be cut to allow the joiners to slide inside the spar. If you wait until the end to cut the ribs they'll be inside the spar and next to impossible to cut out.

This is a nice looking glider and flies very well. The lighter you build it the better it will fly. I completed my Sunbird this winter in about six weeks. Ready to fly with battery it is 425 grams. All it needs now is some good weather and warm rising air.

IMG_2299.JPG IMG_2334.JPG

Jon
 
#47
Pay close attention to Joker's advice, especially where the wing sections join. The kit instructions don't tell you how to join the wing sections. Ribs have to be cut to allow the joiners to slide inside the spar. If you wait until the end to cut the ribs they'll be inside the spar and next to impossible to cut out.

This is a nice looking glider and flies very well. The lighter you build it the better it will fly. I completed my Sunbird this winter in about six weeks. Ready to fly with battery it is 425 grams. All it needs now is some good weather and warm rising air.

View attachment 104104 View attachment 104103

Jon
29134571_10216425641694804_2106274694_n.jpg

Hi

You mean like on that photo?.


tks very much to let me know some info.... Really i need them because is my first built for me .

so good luck for your test flight soon.
 
#48
You mean like on that photo?
Yes. Like the spots marked in red in the photo. Those spots have to be cut out for the plywood joiner. Looks like the photographer is showing where he wished he cut out the ribs before he glued in the webbing. :confused:

The Sunbird has flown a couple of times. There is a video. Both times it was too cold and windy to be enjoyable. It handles wind quite well. Probably good for slope soaring. Wish I knew a suitable hill.
 
#49
Here is how I did the wing joiner. First photo is the joiner dry fit inside the ribs and upper/lower spars. No webbing glued in yet.

IMG_2239.JPG

This next photo shows joiner dry fit into the spar with the webbing glued in. No glue on the joiner at this point. It can slide in and out.

IMG_2242.JPG
 
#51
Yes. Like the spots marked in red in the photo. Those spots have to be cut out for the plywood joiner. Looks like the photographer is showing where he wished he cut out the ribs before he glued in the webbing. :confused:

The Sunbird has flown a couple of times. There is a video. Both times it was too cold and windy to be enjoyable. It handles wind quite well. Probably good for slope soaring. Wish I knew a suitable hill.
hi tks very much....so the hobby king shipped mine today ...... looking forward to start. And post some photos here.


so i added you in my contacts lol!!. :).
 
#52
Very nice job!!!..... well done!!!

Here is how I did the wing joiner. First photo is the joiner dry fit inside the ribs and upper/lower spars. No webbing glued in yet.

View attachment 104177

This next photo shows joiner dry fit into the spar with the webbing glued in. No glue on the joiner at this point. It can slide in and out.

View attachment 104178


Very nice job!!!..... well done!!!...... AND TKS VERY MUCH FOR THE INFO.
 
#53
Hey Joker, the instructions from you and the other builders before me made building the Sunbird without a lot of cussin' and fussin' possible. It was a fun build and a great flying bird. It got me hooked on balsa again. I have three old timer kits from the 30's and 40's arriving today. They are going to be modified for electric motor and RC. I'll still build foam board in between balsa builds. Foam is fun but balsa is better!

Jon
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#55
Interesting, I never saw the plan until a year after I built mine. Somebody must have done some work designing it, as it is certainly something that should have been included with the kit!
 
#56
The full size plans are a helpful reference. (Almost full size) If you scale it up about 1% it should be accurate. You will notice that some of the part numbers on the plan are not the same as the numbers in the Hobby King instructions. Pick one numbering scheme and stick with it.
Jon
 
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Joker 53150

Mmmmmmm, balsa.
Mentor
#59
Looking good!

Be careful with that style pin, I've had that round head break when I'm pushing on it and had the pin's flat end stick in my finger before, not pleasant at all...! :( Yours may be better quality than the ones I had, but they still make me nervous to the point I threw mine away.
 
#60
Looking good!

Be careful with that style pin, I've had that round head break when I'm pushing on it and had the pin's flat end stick in my finger before, not pleasant at all...! :( Yours may be better quality than the ones I had, but they still make me nervous to the point I threw mine away.



Tks joker for let me know. ..you right about that but till now never had that problem.