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Old Dec 26, 2011, 11:10 AM
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Knoll53's Avatar
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Horten Glider -Alpine Sled....code name "The Manatee"

As a descendent of Andres Beluga glider, I have sketched a stretched thermal version of the Beluga called the Alpine Sled. I fly booming thermals out in an alpine environment and need a large durable glider for the task. Horten style ships fit in well out there with the turkey vultures and hawks. Many hikers will come up to me while I'm flying my little Horten just off of the trail and say that they saw my glider and first thought it was a bird. Cool...... that's what I'm going for.

Kent
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Old Dec 26, 2011, 02:33 PM
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Kent,

I'm on board for this glider as well as your Horten hang glider. It looks to be a very exciting 2012.... filled with flying wings.

Vern
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Old Dec 26, 2011, 02:35 PM
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There may be more than one version. This one is rather big in my book. I'm guessing 6 lbs. of plywood and lead.
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Old Dec 29, 2011, 03:29 AM
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Hi,

I adapted and made an initial import of the geometry. I also created a SourceForge project for the Manatee:

https://sourceforge.net/projects/hortenmanatee/

The geometry is pre Alpha, so I'm still working on it and many hour of work are still needed until the plans for a prototype can be started. I published the files under European Union Public License.

Regards,

Andrés

p.d. For your pleasure, I attached a screenshot of the design.
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Old Dec 29, 2011, 09:38 AM
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You've been busy !

Looks good. You are the aero-designer so please feel free to modify anything as needed. I was thinking since the planform can affect flight characteristics you may possibly want to adjust that.

Thanks Andrés
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Old Dec 29, 2011, 11:55 AM
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Kent,

I actually changed already the planform . I increased sweep and also changed slightly "das Horten-Schwänzchen". I like the looks of your planform. However, it shifts the c.g. of the geometry quiet to the back because of the high wing depth at the tips. But, I would rather not want to reduce the depth to avoid a subcritical flow there. So, what might happen is that you'll need quiet a lot of lead in a glider version . You should make the tips as light as possible... In a motorized version, the batteriy weight should do the trick .

To be sincere, I have done my calculations for 4.5 kg instead of 6 lbs (=2.7 kg), beacuse from my experience, it will be very hard to produce such a light structure (including lead!) without ending with an oversensitive wing. Even so, the airplane should stall below 40 km/h (25 MPH), which is a quiet good value.

Greetings,

Andrés
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Old Dec 29, 2011, 12:37 PM
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Yes, I am with you on all of that. The planform looks great.

6 lbs. (2.7kg) was definitely dreaming. I AM shooting for 8 lbs. (3.6kg) which would be the same wing loading as a similar conventional ship I've built, but I understand that this one may require more lead. After all, a Horten style ship does not have a long fuselage up front to maximize forward weight. Maybe the real number will be 8 lbs. plus lead. 9.9 lbs. (4.5kg) would be fine, especially if it can fly as slow as 40 km/h (25 MPH). With this size of a ship, that will appear to be crawling.

Either way, it is no problem. It is a BIG ship. I plan on building light weight tips and a heavy nose. I'm already weight training so I'll be ready for the massive bungee that will be required to launch this one. Should be fun. Big launches are not needed for me because I fly way up on a mountain and only need 20 seconds of air-time to head out and find a well developed thermal.

I'm already buying parts for this one.

regards,
Kent
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Old Jan 03, 2012, 12:15 PM
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Hi,

I had time to work on the Manatee during the last days. I calculated the CG range and updated the DXF file.

The latest version v0.02 is found at:
https://sourceforge.net/projects/hortenmanatee/files/

The DXF file includes now the airfoils, the CG. and the most aft CG position. The airfoils in the file still have to be placed and rotated correctly (TODO for v0.03 ).

Proposed CG (for a maiden): 390 mm
Most aft CG (Danger!): 411 mm
Landing speed @ 4.5 kg: 37 km/h

Greetings,

Andrés
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Old Jan 03, 2012, 12:42 PM
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Great Andrés. I have downloaded all and the design of the airfoils are quite interesting. Apparently there are a variety of different airfoil profiles.

Kent

Edit:
Please feel free to provide rotation of airfoils in any format that is convenient for you. We can work from most any data. The elevon is clearly shown.
Thanks for your efforts
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Old Jan 04, 2012, 09:54 AM
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Quote:
Originally Posted by andrecillo76 View Post
Landing speed @ 4.5 kg: 37 km/h
37 km/h = 22 mph. Like it. So if I can build lighter than 4.5 kg, my landing speed will be even less. It looks as though there will be a significant "payload" of lead in the nose to achieve the CG. There is a lot of wing behind that CG.

This required payload should lend itself well to substituting some of that lead for a camera mounted at the nose or even in front of the nose (with a skid).

Note to self.... make the lead modular and demountable.

Kent
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Old Jan 05, 2012, 03:52 PM
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Have you come up with an airfoil more suitable for the sort of reynolds numbers our models fly at? The one in the first post seems overly thick even for a big heavy model size flying at a fair speed. I can see a lot of airflow sepration issues being created by the strong upper side curvature.
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Old Jan 05, 2012, 03:57 PM
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Friday is free here, so I worked at the Manatee until now. I did the last work on twisting the airfoils and produced two versions. The first one has the hingeline on top, while the second one has it at the center. So please choose the right one. I rather like the one on top, because I can use adhesive tape to hinge the elevons. If you use plastic hinges, you should probably take the other one and place the hinges at the center of the secant cutting the airifol at the hinge line. Sounds fancy, but just have a look at the DXF and you'll get it

You find the file at:

https://sourceforge.net/projects/hortenmanatee/

Just keep in mind, that I published the "stuff" under the european public licence (EUPL), which uses copyleft. This means in escence that you can make plans for yourself as you wish using my information. If you publish plans based on my files, you'll have to publish these also under the EUPL. So I'd suggest in that specific case to contact me and we commit the plans to the SourceForge webpage. The copyright stays at the author, of course!

@Kent: It's still a prototype, so you should always use a certain amount of demountable lead . I hope the minimal speed calculated correspond to the true one. It is like playing lottery whe it comes to such non-linear problems

Regards,
Andrés
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Old Jan 05, 2012, 04:15 PM
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Quote:
Originally Posted by BMatthews View Post
Have you come up with an airfoil more suitable for the sort of reynolds numbers our models fly at? The one in the first post seems overly thick even for a big heavy model size flying at a fair speed. I can see a lot of airflow sepration issues being created by the strong upper side curvature.
Well sure, you are right under the assumption of an ideally produced airfoil. That's in general the problem of using a thick airfoil at low Reynols numbers.The thing is that, none of our models has a perfect surface . The airfoil of the Beluga is even more curved than the one of the Manatee and the measured data shows a L/D of 10 at an AR of 5.5, suggesting that separation cannot be too bad. However, I suspect that the Dutch-Roll in the Beluga is induced by separations (still to check). I modified the airfoil of the Manatee because of this issue. We'll see what happens

Regards,

Andrés
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Old Jan 05, 2012, 05:13 PM
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Originally Posted by andrecillo76 View Post
Friday is free here, so I worked at the Manatee until now. I did the last work on twisting the airfoils and produced two versions.
Just keep in mind, that I published the "stuff" under the european public licence (EUPL), which uses copyleft. This means in escence that you can make plans for yourself as you wish using my information. If you publish plans based on my files, you'll have to publish these also under the EUPL. So I'd suggest in that specific case to contact me and we commit the plans to the SourceForge webpage. The copyright stays at the author, of course!
Regards,
Andrés
Yippie for "Free Friday". Thank you very much for your work. The drawings look great and I will use the top hinged version. Also, thanks for modifying the airfoil to mitigate possible separation issues. Based on your video, I have no worries as to this planes behavior. I will build with plywood and Koverall ( doped on polyester fabric ) so it should be in the "rough" surface classification.

I am still amazed that such a thick airfoil can be workable for a model this size so flight testing will be very interesting.

Let me ask about "copyleft" agreement. I plan on publishing my drawings derived from your work here in this forum as part of the build log. I trust that that is an acceptable use. Let me know if there are any restrictions. As standard practice in my drawings, I will list you as the designer and copyright owner.

Let me know if I can return the favor and thanks again. Now I'm off to Rhino 3D for some initial images.

Regards,
Kent
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Old Jan 05, 2012, 07:01 PM
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A quick look around

Main surfaces are modeled with straight hinge line.
Red = top
Purple = Le
Green = bottom

Kent
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