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  #11  
Old 12-23-2014, 09:00 PM
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mbauer mbauer is offline
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Originally Posted by hikokibert View Post
I finished it. It looks great. It came out at 18g or 5/8 oz according to the kitchen scales. It balanced at the cg without any weight added. I found the slit for the tail was a little short. I extended it back to the jet nozzle. The wing fit perfectly.
Initial test glides indicate it is a touch nose heavy. It is a bit hard to do any more testing today as it is very humid and the flying surfaces are a bit too soft to trim. Also it has just come up windy.
I have probably made it a bit too heavy. If I substituted balsa for the laminated fuselage and just used thin paper for the cover it would be lighter.
Once I get the trimming done I will shove a pin in the bottom somewhere in front of the cg and try it as a catapult launched glider. The weight could help in thus situation.
I really enjoyed making this. It was a real quick build.

Robert
Awesome! Glad you liked it! Any ideas on how to improve will be greatly appreciated!

thinking of an actual airfoil shaped wing (top and bottom and tips to hold the shape), do you think it will create a much more complex model?

great Photos!

Mike
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  #12  
Old 12-23-2014, 09:52 PM
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Robert Woolley Robert Woolley is offline
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For this size model I think a full airfoil would be a step backwards. Extra weight and at the slow speeds of a glider I think the current airfoil is more effective. I think a rib at half span to hold the airfoil shape would be good. I would also have the vertical tail in the middle laminations but not the outer ones to allow it to be a bit thinner and able to be trimmed more easily.
I went out and tried again with a bit of weight on the tail. I got a couple of very short level flights but the wind is too gusty to really learn anything. I did get a flat spin at one point which looked interesting.
I need to make another one. I used white glue for this but will use balsa glue next time. The humidity and white glue make the wing too soggy. The acetone based balsa glue would be lighter and make the wing stiffer I think.
If this was a normal glider I would put a little negative incidence on the tail, but as this is scale and the tail is so close to the wing I wonder if it would have any effect.
Anyhow trimming is half the fun of flying models.

Robert
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  #13  
Old 12-24-2014, 05:17 AM
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Hudsonduster Hudsonduster is offline
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Mike, I just stumbled across this thread. I've got a bit of free flight experience myself, & if you still need beta builders I'd like to have a look at what you're doing here. I noticed Robert's comment about the rleative wing & stab incidence, and suggest that for any of these little gliders we need a three degree stab tilt to give us lateral stability. Swept wing planes need less or maybe no dihedral. An 8" w/s A-7 I did a while back took about 3/8" per tip, which was hardly visible, and a 20" w/s M-4 Bison had none.

Trouble with swept planforms is, they're TOO stable and don't want to transition like a straight wing glider. I'd launch the Bison level, it went level. I launched it at an angle and it'd go up 'til it lost momentum, stall, and come straight down. The A-7 was much better, getting about 60% flights off the catapult, and the rest it didn't transition but stalled & spiraled in, not quite a flat spin.

I'd love to take a whack at what you've got, if you still need. PM me please -
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  #14  
Old 12-24-2014, 06:20 AM
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Robert Woolley Robert Woolley is offline
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I have been able to do a bit of still air testing. It glides with a dead straight, dead level launch. Just using a flick of the wrist, like throwing a dart. It didn't glide very far due to the weight but a glide never the less. Most enjoyable so far. And after reading Hudsondusters comments, I am starting to get the free flight bug back.

Robert
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  #15  
Old 12-24-2014, 09:34 AM
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mbauer mbauer is offline
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Quote:
Originally Posted by hikokibert View Post
For this size model I think a full airfoil would be a step backwards. Extra weight and at the slow speeds of a glider I think the current airfoil is more effective. I think a rib at half span to hold the airfoil shape would be good. I would also have the vertical tail in the middle laminations but not the outer ones to allow it to be a bit thinner and able to be trimmed more easily.
I went out and tried again with a bit of weight on the tail. I got a couple of very short level flights but the wind is too gusty to really learn anything. I did get a flat spin at one point which looked interesting.
I need to make another one. I used white glue for this but will use balsa glue next time. The humidity and white glue make the wing too soggy. The acetone based balsa glue would be lighter and make the wing stiffer I think.
If this was a normal glider I would put a little negative incidence on the tail, but as this is scale and the tail is so close to the wing I wonder if it would have any effect.
Anyhow trimming is half the fun of flying models.

Robert
Hi Robert,

On my model it was tail heavy. I did use too many laminations of heavier card backing from notebooks.

Was thinking of adding a couple of extra laminations in the front and creating a hook for rubber band launching.

Never thought of the rudder being thinner, your suggestion is a great idea. How many laminations do you think would be best for it? (2 or 4)

Tail incidence is another great idea, after reading the Hudsonduster comments, will probably try a few degrees to see if it helps!

Thank you for your input!

Mike
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  #16  
Old 12-24-2014, 12:38 PM
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thepaperguy thepaperguy is offline
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the wing profile should be fine. the undercamberes wing works for the UMX models on the market so i wound honestly stick with it. if any thing just do a rib at the root once you glue the wing in to hold the shape and one on the tip.
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  #17  
Old 12-24-2014, 02:06 PM
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Hudsonduster Hudsonduster is offline
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After I posted that, I re-thought: the appearance of a model's "sit" as it flies is influenced by the relative incidences of wing & stab, popularly mis-named "decalage" by us F/F'ers. That three degrees I metion is a good starting point, and it often works better to put it in the wing - wing plus three, stab zero. This keeps the nose more level-sitting in the glide, avoiding the nose-high "drowning ferret" look.

Listen, let me do some test models and get back to you before you go crazy redrawing everything. Couple days.
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  #18  
Old 12-24-2014, 06:08 PM
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mbauer mbauer is offline
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Quote:
Originally Posted by Hudsonduster View Post
After I posted that, I re-thought: the appearance of a model's "sit" as it flies is influenced by the relative incidences of wing & stab, popularly mis-named "decalage" by us F/F'ers. That three degrees I metion is a good starting point, and it often works better to put it in the wing - wing plus three, stab zero. This keeps the nose more level-sitting in the glide, avoiding the nose-high "drowning ferret" look.

Listen, let me do some test models and get back to you before you go crazy redrawing everything. Couple days.
Ok, model has been sent! Let me know what you think.

Mike
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  #19  
Old 12-26-2014, 09:14 PM
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I finished my first build of this model today. I decided to build it as light as I possibly could. I did this by printing the color parts on copy paper and the cardstock on 65 lb stock. I began the assembly with a single piece for the full fuselage length. For this part I removed the rudder and top fin. The next two laminations were approximately 1/2 of the fuselage, ending just behind the wing trailing edge. I added two laminations for the nose only and then covered all of these with the color fuselage full halves that were printed on the light weight paper. So the nose has five card laminations the center fuselage has three card laminations and the aft fuselage has only one.

The wings are only one piece of cardstock along with the color piece printed on thin paper. I attached them to the fuselage with tabbed pieces on the underside as shown in the last photo. For the wing, I used a leading edge/wing root support piece on each side. The leading edge supports allowed me to fold a leading edge "slat" in the front of each wing. This is visible in the overhead view. Finally I mounted the wing almost a full inch forward of the location indicated. I did that to improve the effectiveness of the elevator.

The model came in a 10 grams so I was very pleased with the result. To achieve a level glide I needed to trim in quite a bit of "up" elevator as you can see in one of the side views. With that adjustment and a firm toss in a slightly nose down attitude the model flew very well. In fact it flies nearly as well as a foam glider that I made back in the Spring. I included a photo of the foam glider alone and along with the hun for comparison.

Outside I tried a few flights just before dark. I launched the plane with a firm downward toss over a gentle downslope. The best flight ended by crashing into a tree about fifty feet away. The total distance covered was about 70 feet as the model completed a sweeping turn to the right.

The wings were mounted with an angle of incidence of zero and the elevator with about a -1 degree incidence.

For the next build I will probably eliminate the printing on thin paper, use two laminations for wings, tail and fuselage. I will then add laminations to the center and nose of the fuselage to make the model slightly nose heavy. Finally I will increase the negative incidence of the elevator.

Curt
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  #20  
Old 12-26-2014, 09:29 PM
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mbauer mbauer is offline
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Hi Curt,

Awesome! Been suggested to me, to use foam egg carton for the fuselage laminations (or meat ray although they are thicker).

Next design going to use those for the laminations and also a different airfoil shape, about 3 degrees of incidence for the wings too.

Got a big project trying to finish this weekend, then want to design a bunch of these little flyers. Did this one first to hand out to builders to see if they liked them and changes to make them fly better. Been getting lots of positive feedback!

Your foamie looks like it is a great flyer!

Mike
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