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Old Dec 28, 2013, 08:23 AM
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United Kingdom, Sidcup
Joined Jun 2012
269 Posts
Pretty Wings but what flyes best?

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Originally Posted by War is Peace View Post
I have hundreds of flights on it and it has been tons on fun. Current all up weight is 278 grams (9.8 oz) after a few minor repairs and changes. Here are some of the things I have done and recommend for your new build.

Your AUW is very good :-) You must be very careful how you build :-)
Quote:
1. Replaced the built up ailerons with laminated solid balsa. (I shredded the built up ailerons with flutter when I throw too hard - and have broken several servo arms)

How do you go about the lamination to control the weight? If you are after stiffness to stop flutter there may be a laminating method that keeps down the weight while increasing the stiffness a lot?
Quote:
2. Ailerons don't go to end of wing. I cut of about 1" off the tip of the aileron and glued it to the wing tip. (protects the aileron and servo if you land on a tip)

The tip design section on the Manta looks pretty but it must have issues with the Reynolds Number for flight characteristics. The designed tip is probably useless for giving lift. Similarly the aileron out there can't be doing much good. So fixing the last 5-10cm of the aileron tip may make no difference or could reduce drag. Does such a tip clean up the tip vortex? The shape also makes throwing peg placement a problem for finger web fouling. It may be just pretty or pretty useless?
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3. If I were to build another, I would consider decreasing the chord of the ailerons. (move the wing trailing spar rearward about 3/8") I still have a flutter problem during a hard launch. I think narrower ailerons would be OK because the stock ailerons have more than enough control.

It is not about control. Using exponential on your TX may help. Also, check aileron horn design and control geometry layout. Top drive ailerons are used quite a bit. The position of the aileron/flap hinge in chord width terms is an aerodynamic issue. Making the ailerons narrower will screw up the wing section/flap profile for aileron/flap deflections. Particularly when flap or air brake deflections are used. It would be wise to study the design of more modern DLGs to see how much chord is given over to ailerons for best performance. Flutter reduction is covered here too:-

http://olgol.com/TabooXL/aileron-LE.html

https://www.google.co.uk/search?neww....0.uZtWoS7VTXo
Quote:
7. My battery is a 350 NiMh. (1/3 AAA cells)

The power density in NiMh is low compared to LiPo so you can have bigger lighter batteries, with more stored power, if you want:-) Also LiPo can be charged more quickly and they are very well priced for their capacity :-) Time to look at new battery technology ? :-)
The Manta is pretty but the modern composites are showing the way.
As designed the Manta is a great building project. Aerodynamically out dated though. It can produce a light weight flyer below 10oz :-) It can also reduce the built materials price? This is debatable and a price for all new materials and parts is not available.
Shipping/collecting materials has a cost too. It may not be very cheap unless you have plenty of the right materials already.
It will take up a lot of time sourcing the best materials as well as building and covering time. The covering is also costly.
There are so many modifications proposed to the basic design so you will have to sift through and find the best ones. Even composite pods are in the mix.

Given what has been written, losing the pretty plan form may yield improved flying, aerodynamic and throwing characteristics.

Finally, this is not a beginners project or a way to get a low cost DLG that gives composite model performance.

You will get a lot of open mouthed admirers if you build this and it is VERY PRETTY :-)
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Last edited by Mal Bond; Dec 28, 2013 at 08:28 AM.
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Old Jan 05, 2014, 10:14 AM
Egads! It's a GIRL!
Lil Stinkpot's Avatar
United States, CA, San Jose
Joined Jul 2011
3,224 Posts
I don't think it was ever meant to be a seriously competitive model, just one that can be built at home and bring a smile while you fly it. Just like a Bug, but bigger.
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Old Jan 05, 2014, 05:19 PM
Registered User
United Kingdom, Sidcup
Joined Jun 2012
269 Posts
The Manta is a 7 year old design :-)

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Originally Posted by Lil Stinkpot View Post
I don't think it was ever meant to be a seriously competitive model, just one that can be built at home and bring a smile while you fly it. Just like a Bug, but bigger.
Thanks for your input Stinkpot :-)

Being honest the Manta is a 7 year old design :-)
I liken its evolution to a computer with one major difference :-)
The Manta has its roots in the Great design clarification provided by Dr Mark Drela almost 10 years ago :-) His SuperGee II was the seminal design for 1.5M DLG that we see today :-) http://www.charlesriverrc.org/articl...SuperGeeII.htm.

The big difference is that computers double their performance every year. Sadly flying aircraft have to live in the real world of air resistance and gravity. So refinements are rarely major step changes. Airfoils, weight reduction and drag reduction are the main areas where improvements can be made.

So we get better airfoils starting with the AG455 of Drela to the Zone-V2 of the Fr3ak - http://www.rcgroups.com/forums/showt...e#post22851586.
We use composites to improve smoothness of lines and reduce weight.
Then we try various RC gear layouts and control paths to reduce drag and weight.

So the Manta was good for 7 years ago but not a top design even then. People have tricked around with it since to improve it a bit but it is very dated now.

The built up construction method is now a very time consuming build method and quite advanced for new builders. It requires very careful selection of materials and adhesives as well as very precise construction to get the needed airframe strength.

So I stay with my real world point that the Manta looks lovely but is a heck of a building and covering project. It will fly like a 7 year old average DLG and I agree it will not be a competition model.

So build it for that feel good feeling that "I made that" :-) Then cover it in a pretty design and watch all the observers marvel at how pretty it is.
Then go fly it as a fun DLG that can catch a thermal and be very enjoyable to own. Hopefully it will bring in a few people who want a good starting model and don't want to may 2-500$ to get a mid range DLG.

Sadly there is a ready made DLG that is probably cheaper than you can build a Manta and flies at least as well ($103 + shipping). designed for Right Handed throwers :-

http://www.r2hobbies.com/rc-aircraft...ider-7988.html

http://www.rcgroups.com/forums/showthread.php?t=1981135

There are a few deficiencies and you may have import duty to deal with but you can get it and be flying it in a couple of days. This will give you the DLG bug for flying and then you can move on to the composites to get lower sink rates, greater penetration and improve your piloting skills once you are sure DLG is your thing :-)

The Manta remains a beautiful looking DLG with very average flying characteristics after a lot of building and covering. It is unlikely to cost less to build than the Specter's delivered price. The flying will be much the same.

So it is up to the reader to think where they want to put their time effort and money. I vote for flying the DLG every time. I used to love building from balsa and other materials but the flying is what it is all about for me these days :-)

Wishing you all Happy, Successful DLGing :-)

Mal :-)
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Old Mar 08, 2014, 06:24 PM
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thewildweasel's Avatar
Plymouth, Devon
Joined May 2007
2,443 Posts
I've just started building a Manta, thanks for the plans Geode. I like them a lot - very minimal to allow for easy changes, but with all the details you need. I discovered the plans and a lot of your other work a month or so ago when I started researching how to design my own gliders and I like a lot of your ideas

I've made some changes myself, mainly to the D box, eliminating the ribs there and replacing them with a former and spars to form the aerofoil. I'm also down-sizing the actual spar assembly as I'm not sure I'll be DLGing this wing - I need to get back into flying after a few years off first. I did build a spar as per plans but at 50g for just the front pair I decided that that was too heavy and scrapped them.

Build details start at post 5 in my blog www.rcgroups.com/forums/showthread.php?t=2116021 and I can post some pics and details here as well if anyone's interested.
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Old Mar 08, 2014, 06:43 PM
1984 is no longer fiction
War is Peace's Avatar
United States, FL, Sun City Center
Joined Mar 2012
366 Posts
My Manta has finally fallen apart. As I became better, my throws became harder and the aileron flutter became worse and worse. I've blown up several servo arms and also blew carbonite gears out of my HiTech servos. Ive over stressed the wing mount. I've torn servos loose in the wing. I've snapped the balsa pod off the front of the carbon boom. I've ripped out the elevator on launch. The poor thing had been through the mill.
That being said, I'm glad I built it. I was able to learn on something inexpensive, that was easy to repair. I'm now flying a Blaster and my experience learning on the Manta has proven invaluable.
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Old Mar 12, 2014, 11:27 AM
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hog2soar's Avatar
Central California
Joined Jan 2010
919 Posts
Here's what I did to a Manta

I wanted to build something different so this is what I did to my second Manta.

I stretched it to 72" and made it a Gull Wing and electrified it.

There's kind of a build log in the Thermal section if your interested.
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Old Mar 12, 2014, 12:44 PM
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dion9146's Avatar
United States, KY, La Grange
Joined Feb 2006
1,600 Posts
That's a pretty little plane.
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Latest blog entry: Big Gull plan pics
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Old Mar 12, 2014, 01:18 PM
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United Kingdom, Sidcup
Joined Jun 2012
269 Posts
Scratch built Manta 72" Gull Wing

Quote:
Originally Posted by hog2soar View Post
I wanted to build something different so this is what I did to my second Manta.

I stretched it to 72" and made it a Gull Wing and electrified it.

There's kind of a build log in the Thermal section if your interested.
Hi hog2soar :-)

Thanks for the heads up on your advanced upgrade to the Manta :-)
I have put the link here to your other thread so others can find it easily:-

http://www.rcgroups.com/forums/showt...ighlight=manta

Your remodeling of the Manta looks very beautiful :-)
It is good to see that that designed strength of the Manta works well in the new role you have given it. Great that the Manta DLG design works well for electric.

It will be great to see what it flies like and I hope your other thread will fill out with flying info.

It is so good to see that a skilled builder can produce such a lovely upgrade to the already gorgeous Manta.

Well done :-)

Mal :-)
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