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Old Jul 07, 2007, 08:37 PM
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Santa Clara, California
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Rendy's Manta construction diary (continued)

Well... I have completed the D-box and the servo box. The wing panels in the photos are very rough because I have not start sanding them yet.

Update: The both wing panels together is 4.02 oz. After sanding, 3.8 oz. Currently, I am glassing the TE of the ailerons and wing tips. There is no photos for this because it is very hard to see the difference.
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Last edited by Rendy; Jul 09, 2007 at 01:45 AM.
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Old Jul 12, 2007, 08:17 PM
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Santa Clara, California
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Rendy's Manta Construction Diary

The wing is basically done. It weights about 5 oz.... about 0.5 oz heavier than I expected. I must have put in too many carbon and FG. The covering adds about 0.5 oz.
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Old Jul 13, 2007, 12:27 AM
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Nice covering job. Looks like you will hit 9 ~ 9.5 oz target weight and with a stiffer wing.
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Old Jul 14, 2007, 04:22 PM
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High Geode!

I just read your Thread of this amazing great flyer.
I send you an PM but I don`t know, what button for sending the messege.
So I Send you my messege with all the Buttons, hoping one messege came to you. (my bad english)

Wish you so much Luck with the great bird.

Thomas
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Old Jul 14, 2007, 08:29 PM
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Santa Clara, California
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Rendy's Manta Construction Diary

I have just completed the pylon wing mount. It is modeled after SG2. The inner tube is made from carbon-AL arrow shaft. The outer tube is homemade FG-Kev-FG tube.
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Old Jul 14, 2007, 09:16 PM
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San Jose, CA
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Hi Thomas,

Thanks for your interests. Please check your mail box for Manta plan.

Please also note that Rendy has make several improvements on his Manta to make it stronger and lighter. Wish you enjoy the Manta build and remember to come back to share with us your experience.

Geode
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Old Jul 15, 2007, 12:47 AM
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High Geode!

I thank you so very much for the plans.
Must build my first Bird ready for maiden and then I will build your`s.



Good Luck by this great Hobby to you all!

Thomas
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Old Jul 15, 2007, 10:49 AM
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That's a really beautiful bird !
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Last edited by Geode; Jul 15, 2007 at 11:16 AM.
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Old Jul 22, 2007, 03:36 PM
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Santa Clara, California
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Rendy's Manta Construction Diary

I am done with all the electronics. JR SM22 for RUD and ELE; D60 for AIL. RX Electron 6.
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Last edited by Rendy; Jul 22, 2007 at 07:58 PM.
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Old Jul 24, 2007, 11:29 PM
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Santa Clara, California
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Rendy's Manta Construction Diary (final post)

I have maiden the plane this evening and the following are the lessons learned.

(1) The plane flies great in light wind condition. The AUW is 9.7 oz for my version. Geode's Manta is lighter. However, a 9.7 oz plane is just about right for me. The launch heigh with 60% power launch is about 120 ft easy.

(2) The CG is right on without any nose weight. My initial decaloge estimate is also correct.

(3) The wing has plenty of stiffness in bending. There is no need to add CF spar cap.

(4) The wing is a little bit thick which makes it hard to penetrate into high wind condition.

(5) The wing torsion should be improved a little bit more. It does not cause me any problem, but there are people launch with strong wrist action, which could twist the wing a bit.

(6) The aileron construction is torsional weak. The deflection angle cannot properly transfer to the tip This can be corrected by mounting the AIL servo more outboard and stiff up the structure a bit.

(7) The SG2 style wing mounting method works great even though it takes some time to make.

(8) SG2 style pod is very very small. Careful planning of the components is required. I mean even the path for the wiring.

(9) The nose section of my pod is a bit too weak. Need to put another layer of Kevlar in the nose section.

(10) The wing tip shape needs to be modified to accommodate personal launch style.
rendy
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Last edited by Rendy; Jul 25, 2007 at 09:58 PM.
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Old Aug 18, 2007, 06:36 AM
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San Jose, CA
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Any comments ?

I received lots of requests for printable plan. Surprise to find that there are more than 50% of them are outside US .

How are the progress out there, gentlemen ? I have to confess that, there are a lot of building details not covered in this thread due to my limited English capability. If you have any questions, please do not hesitate to ask in this thread or PM me privately.

Also, feel free to post any comments and recommendations (good or bad, both welcomed) on Manta DLG. I'm more than happy to take that into account for next revision. Thanks.

Happy building
Geode
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Last edited by Geode; Aug 18, 2007 at 10:34 PM. Reason: Polish up my poor English.
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Old Aug 18, 2007, 07:16 AM
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San Jose, CA
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Manta II

A few improvements can be made to Rendy's comments to make it better for Manta II:

(1) The plane flies great in light wind condition. The AUW is 9.7 oz for my version. Geode's Manta is lighter. However, a 9.7 oz plane is just about right for me. The launch heigh with 60% power launch is about 120 ft easy.

The new target weight will be < 9 oz and narrower chord to keep the wing loading the same. This fits well with my constant wing loading principle. Add ballast in windy conditions if necessary

(3) The wing has plenty of stiffness in bending. There is no need to add CF spar cap.

Vertical web width to be reduced from 3/8" to 1/4" for weight saving.

(4) The wing is a little bit thick which makes it hard to penetrate into high wind condition.

I like the penetration capability on my Manta.

We still not come to a conclusion yet on this regarding how to make it better. Is it due to airfoil thickness, larger wing area, non-transitional airfoil @ wing tips, wing torsional strength, balsa building skill or Icarex ????


(5) The wing torsion should be improved a little bit more. It does not cause me any problem, but there are people launch with strong wrist action, which could twist the wing a bit.

This is the most significant difference between build-up vs. composite DLG's.

Rendy use hard 1/16" ribs in his Manta. This probably is not a good tradeoff between weight and strength. Hard 1/8" or 3/32" ribs may be a better compromise between strength and weight penalty.

Also, I like the looks and strength of diagonal ribs in Hyperbolic Manta. This will be there for Manta II.

Last but not least, geodetic ribs like "Bumblebee XL" will add another big jump in torsional strength.


(6) The aileron construction is torsional weak. The deflection angle cannot properly transfer to the tip This can be corrected by mounting the AIL servo more outboard and stiff up the structure a bit.

Looks like I'll stick to my solid balsa or balsa (or CF) capped build-up aileron in the future.

(7) The SG2 style wing mounting method works great even though it takes some time to make.

I have >100 launches and landing on Hyperbolic Manta with balsa pod. This will be used for Manta II instead of composite pods.

Geode
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Last edited by Geode; Aug 18, 2007 at 07:47 AM.
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Old Aug 18, 2007, 02:06 PM
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Hi Geode,
THanks for the update. I hope to work on my Manta once I finish my Apogee Sport.
Ray
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Old Aug 18, 2007, 02:47 PM
.: Looking for Thermals :.
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Chile, Quinta Región de Valparaíso, Los Andes
Joined Jun 2002
864 Posts
Hey Geode,

Do you cut by hand your ribs or you laser cut them?
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Old Aug 18, 2007, 10:19 PM
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San Jose, CA
Joined Jan 2007
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I glue (with 3M77) two 1/8" balsa together and then hand cut the ribs (50% improvement in throughput) :-).

I'm currently working on a new methodology on my pet project to make the balsa building process more builder friendly. If it works out properly, I might come back to incorporate that into Manta II with laser cut.
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