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Jan 23, 2007, 10:46 PM
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Thread OP
I wanted a 1m DLG, so I went with the Bobolink. I was looking at the Zuni DL as well (1.2m wingspan - not on their website yet, but Andre sent me plans for it and it looked nice), but after talking to Andre on the phone, I ended up going with the Bobolink. I very well might get a Hybrid DL at some point in the future, too. I really, really like the looks and build quality of these planes. Let's see if I like the way they fly...

Best,
Al.
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Jan 24, 2007, 12:34 AM
M Seid
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That layup on the wingtip inspires lots more confidence. Very nice. When you put in the peg- check out ASKs technique on peg mounting here. https://www.rcgroups.com/forums/show...545273&page=49
Jan 24, 2007, 02:48 AM
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Thread OP
I glued the boom in place, and set up the pushrod housings inside the pod. While I was doing that, I inadvertently dripped thin CA all the way down inside the boom and made a mess of CA on the fin and rudder! I sanded and cleaned it off as well as I could, but it doesn't look that great - not to mention the extra weight... We'll see what happens.

I also reinforced the rudder with a diagonal piece of CF tape. I didn't take pictures, but I probably will tomorrow.

Good night!

Best,
Al.
Jan 30, 2007, 05:05 AM
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Thread OP
The build is almost finished, with only some minor gear installation and balancing still to do before the maiden flight. I can't wait!

I hinged the ailerons using some 3M multitask tape left over from my Mycro build. I used one strip on top and one on the bottom, and it works great.

For the rudder and elevator servos I used HS-55's, which I taped together at an offset, and CA'd to the side of the pod. This leaves enough space underneath the servos to run the aileron wires and the antenna through. For the ailerons I'm using D4.7 servos, which I just got in the mail today. These are skinny enough to fit in the wing with no problems.

While installing the elevator control horn, I screwed up and placed it a little too far from the boom. This would've created some binding of the elevator pushrod, so I had to carefully pry the horn off the elevator, fill the old holes, drill new ones, and install it again in the right spot. You can see the old (filled) holes in one of the attached pictures. Other than that, everything has been going smooth.

Still to go: solder extension cables to aileron servos and route them inside the wing, install wing servo covers, install receiver/antenna, find proper CG, ang go fly! I'm hoping that the plane will balance with just a CR2 battery pack in the nose, but it may be necessary to go to a CR123 pack, or add some nose ballast... we'll see.

One thing I'm having an issue with is something that a lot of people have said about Art Hobby planes on these fora in the past: the weight of my plane without any electronics, pushrods, et cetera, (just the boom, pod, tail group and wing) is 165g. Art Hobby's website, however, advertises the "glider weight" (evidently an attempt to obscure the actual AUW by not including any kind of electronics and other gear in the published spec) as being 137g. Where are these extra 28g in my plane coming from? that's a whole ounce! Why not just come clean about the weight of their planes? If they were just honest, they would probably have less of a reputation for making chubby planes simply from the fact that people wouldn't be posting about it all over the internet! Anyway, that's another thread...

Pics attached, comments welcome.

Best,
Al.
Feb 02, 2007, 03:09 AM
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Thread OP
Well, I finished my Bobolink a few days ago, but haven't had a chance to balance and fly it. One thing that's bugging me is the fact that the CG came out 74mm from the leading edge - 11mm aft of where it should be according to the plans. This means I now have to add 15g of nose ballast to the plane (even using the heavier CR123 battery pack and HS-55 servos in the pod), which presents a problem, since there is simply no space to jam 15g of anything anywhere near the nose! By looking at almost any other glider out there, it's clear that this pod is too short to balance the plane without additional weight. This is just bad design, which is especially egregious considering this glider is already quite heavy at 265g (280g after adding the nose weight, for a wingloading of 19.8g/dm^2).

Another thing that's really got me pissed is the fact that the Art Hobby wesite lies about the weight of the glider. I understand a 10, 20, or even 30g difference between their published weight and what you actually get. But this is more than double the weight they advertise! Are they serious???

I gotta say it does look BEAUTIFUL, though... This plane is really stunning! If I were making the kit, I would probably try to save weight by cutting holes in the foam at strategic locations before sheeting the wing, and selecting the wood veneer for least weight. Also, the pods simply need to be longer.

I'll post some pictures when I'm not so tired.

Best,
Al.
Feb 02, 2007, 04:19 AM
M Seid
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I posted a couple pics of my colibri fuse hush wing hybrid that came out to 11.2 ounces with 6 servos. Full house at 11.2 and 60" wing. There is a vid of it in that section. 9.3 ounces for your plane sounds like a good weight for a 1.5 meter dlg... Most of my 4 AH planes came in too light. I wanted tail reinforcements, etc. The paint and epoxy and Ca add up, especially in the tail. Are there some things you can do to lighten up the tailgroup? I have a xp 4, and I made a new elevator for it. 6 grams without deft spray coat. 11 grams with 2 light coats! I sanded it right off... Look forward to the flight report. Good luck.
Feb 02, 2007, 02:01 PM
Registered User

Weight


I will have to argue the weight issue (a bit):
I have to say that I like Art-Hobby approach to ‘weight advertising’ = giving the total weight of the glider only (no electronics etc). That way I know what I am starting with, and I know the total weight of the stuff (rx, servos, batt, glue, etc) I will be adding to it > I can guesstimate my final weight myself. I think that that approach is more objective. On the other hand, I wish they listed the total weight of their prototype model as well. That way I could see how far I am from the ‘expert’ build.

My Bobolink came out:
215g – total weight
with: 4x GWS Pico BB servos, FMA M5 rx, 4.8V-250mAh Nimh
6.3g – extra nose weight
63mm – CG from leading edge (further back then spec)
I put extra: CF pod reinforcement (I don't think it was really needed), servo covers, throwing peg, bottom stained navy blue, top natural clear finish – other then that it is stock. I think that once I subtract the weight of all this ‘extra’ stuff from my total weight, I am pretty close to Art-Hobby specs.
I am building Art-Hobby Castor now, I have not done the final weight – but I think it is very good.
Just my 2C – maybe clarification helps a little.
Wojtek
Feb 02, 2007, 02:31 PM
Registered User
Yup, the weights on the AH website are for the kits as delivered, and not RTF weights. The smaller 1 meter AH gliders do tend to build a bit heavy, but Al’s final weight for the Bobolink is about the same as I’ve seen mentioned for others (basically pretty similar to Colibri builds). Wojtek’s 215 g (7.6 oz) AUW is exceptionally light, but still a bit heavy for a 1M DLG.

In any case, Al’s Bobolink looks great, and I look forward to seeing a flight report.

FF
Feb 02, 2007, 08:19 PM
Registered User
Thread OP
I took my Bobolink out earlier today. I taped a couple of quarters to the nose to balance the glider, and after a couple of throws over tall grass, I was pretty impressed with this airfoil: it really packs a lot of lift, even with the plane being so heavy! I was getting really excited with how far and how responsive it felt on the javelin throws, so after I got it trimmed out, I tried a side-arm launch... Disaster! The glider just yawed and rolled to the left, stalled about 25 feet off the ground, and then came straight down. I tried to save it, but it cart-wheeled and broke the rudder. It cracked vertically in half. Reading some of the previous Bobolink threads out there, I remember someone had this exact same thing happen. Lesson learned: this plane really, REALLY needs some right rudder launch preset!

I'm a lot happier with the plane now than I was yesterday, though. It may be a little heavier than I'm used to, but the wing really compensates for it. It just floats! Tomorrow is supposed to be extra windy, but I'll try to go back out with a fixed rudder and a launch preset. Can't wait to actually fly this thing!
Feb 03, 2007, 12:34 AM
M Seid
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Quarters belong under your floormats in your car, not on the nose of your new plane that you spent all this time and hard work building. Are you going to re do the rudder completely- new balsa etc or repair what you have? AH sells a the Hyper DL rudder with it pre glassed, and it was light enough to use on one of my contest planes. If you try a fresh rudder out of good 3 or 4 mm balsa, and skip the carbon and the CA on the reinforcement, maybe even make it slightly smaller, do you think it would be enough to eliminate the nose weight completely? It seems like the more you can concentrate on lightening up the tail, from removing color, or using z bends etc.... I know you are thinking about all these things too. Its just that your last 2 posts you sound dissapointed. I dont want to sound like Im team AH here, but I just havent had anywhere near the experience that you are having. I hope that plane sets itself straight with you soon. Good luck!
Feb 03, 2007, 11:25 AM
Registered User
Thread OP
Yeah, I must admit I am a little disappointed. There are just too many small little things that I wish had been addressed before releasing this kit (poorly written and vague instructions, misleading weight spec, wrong servo recommendation for the wings, pod too short, stab mount bolts too long and metal, et cetera). Also, about the weight issue, you gotta understand that my only other point of reference is my Gambler AG, which I built to 190g AUW, and has a 1.5m wingspan...

I didn't really do anything to pile on all this extra weight, other than exactly what Art Hobby recommends. Is it the Deft lacquer? the polycrylic on the tail? Did I drip too much CA down the boom when gluing the pushrod housings? I wish I had weighed the parts before and after each step to see where the chunkiness is coming from... Well, I'll definitely do that when I put my Castor together!

Back to the broken fin: I'm going to fix it for now, but I'll also order a new tail group from Art Hobby, and try to build it as light as possible. I really need to glass and CF the fin, though, since this bird is too heavy and flies too fast to leave the wood bare. Building it light will be a challenge...

Another thing I was thinking was laminating two pieces of 1/16" balsa with iron-on CF tape sandwiched in between, sanding the "sandwich" down to 3mm thickness, and cutting a new fin/rudder from that. I have to find some light 4lb. balsa first for that, though, as it will probably be too heavy otherwise.

Best,
Al.
Feb 03, 2007, 02:01 PM
Registered User
Thread OP
Just finished gluing the rudder back together, and sanding most of the lacquer off the tail surfaces and wings. Only saved one gram (dropped to 264g), and moved the CG 1mm forward. So much for that... I knew I hadn't over-sprayed the Deft.

I'm going back in my head trying to figure out what's making this thing so heavy, but I just can't think of it. There aren't that many things that need gluing in this plane...

Best,
Al.
Feb 06, 2007, 05:28 AM
Eternal Flight
I just got a plane from Art Hobby. The info on the net mentioned that it only weighted 13.7 oz. I just finished putting together the wings and it weighted about 11 oz already. I didn't even lacquer the wing yet. Fuselage and battery and lacqure would make the plane about 20oz. I think the ad is a misrepretation. Kind of dissapointed. I might just try covering it do the weight would be down.
Feb 06, 2007, 08:31 AM
Registered User
Quote:
Originally Posted by caodang1120
I just got a plane from Art Hobby. The info on the net mentioned that it only weighted 13.7 oz. I just finished putting together the wings and it weighted about 11 oz already. I didn't even lacquer the wing yet. Fuselage and battery and lacqure would make the plane about 20oz. I think the ad is a misrepretation. Kind of dissapointed. I might just try covering it do the weight would be down.
Sounds like you bought a 2-meter glider. And at a flying weight of about 14 oz, your glider would have been remarkably light and unable to penetrate all but the lightest wind. However, you will find that a 20 oz 2M plane will fly very nicely, and will still be on the light side under many conditions. In any case, I’m sure you will enjoy your glider. However, I do agree that glider weights should simply be posted by AH as empty weights.

FF


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