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Dec 26, 2018, 11:48 PM
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Build Log

VeLectro 2.8 mvg


Transitioning from sub 2m to 2.8m VTPR type gliders is a large leap but actually the bigger ships I found out are easier to fly and control low (2 wingspans or less) in proximity to the ground. Especially the new ultralight 3-4m carbon ships coming out now. But who wants to spend $2,000 plus to have fun and more than likely crack it up first time out! Not me and probably not you. Six years ago was a large inspiration of my transition period of learning and doing a really fun build, the SONIC 2.5 world class VTPR glider with great satisfaction flying closer to Earth.


After the long process of sourcing the fuselage and gaining inside information out of France on how to assemble the Sonic I learned so much about wing and airframe planforms and layups, flight control surfaces and mixing. She came out at 63oz. Then always the designer and builder type, I had to test my skills with the need to design something different and lighter. So with the knowledge gathered from the Sonic, I developed VOL-LENT 2.5 which was flown with success. She ended up being 55oz AUW. Then my wooden PSP line of 1.7m slope VTPR models, ZEPPELIN and STICTION came in at 27-30oz AUW and just a ton of fun to fly!


VOL-LENT 2.5m VTPR (5 min 41 sec)



Zeppelin 1.7m RC Glider (4 min 27 sec)



Shortly after these builds some life changes and priorities came to the forefront that took me away from designing and flying a few years. Then August 2017 I had a bad accident. Full disclosure. I can no longer climb mountains to get to my favorite slopes due to some lingering conditions and pains I suffered last year that nearly killed me. I'm not looking for sympathy, it's just physical facts. I am left with a bum leg I nearly lost as a result of a really bad femur fracture and surgery complications. Now I am carrying around a 13 inch plate and screws in my upper leg to go along with more screws and plates in my lower leg from a motocross racing accident 10 years ago! So that’s that.

Fast forward, I have done all the PT I care to do and I'm healed up as best can be right now, and I have the VTPR bug again. And this time with a renewed fervor and a new type of Vtpr aerobatics not by choice, but by necessity. This kind of effort in the sport of VTPR Aerobatics hasn't been done that I know of in a noticeable way. Flying Slope Vtpr was so cool and exhilarating as compared to general slope aerobatics IMO. You may say what the heck do you mean EJ, slope aerobatics is difficult and amazing to watch and do, how can you say this? Are you dissing slope aerobatics and pilots? No I am not, slope aerobatics was and is what I was grounded in and I highly respect all slope aerobatic pilots. I just can’t physically do it anymore at my favorite flying sites that require a tough quarter of a mile uphill trek, and then back down. It’s not happening, it’s too dangerous for me now, and believe me it’s been a hard pill to swallow.

PARK-VTPR Aerobatics

So, moving on and thinking a lot about flying again this summer, I have come to realize a new and real possibility to explore what I have coined "PARK-VTPR." What is that EJ? PVTPR is going to be flown exactly where I allude. In the park or on any flatland with a purpose built model having electric motor propulsion assist. You heard that right, VTPR low figures on the flat! The reason again, I'm unable to climb to a slope but I can surely drive to a park 30 minutes from the house, unload and walk a short distance to a launch position. So six years since my last slope session I’m pursuing this new glider with hopes to lose another 7-10oz down to 48! Lower wing loading's are a must for PVTPR especially with ZERO lift! After going through all the analysis and figures, and doing the prototype wing panel, I think my target AUW is attainable but we will see.

The prototype MVG (motorized VTPR glider) here will be 2.8 meter span (110") weighing between 1300 to 1400 grams (45-50oz). An F3J type fuse and boom with my new ground breaking extra-large and long symmetrical foam board panels, large flight controls and yes, an electric motor and prop. There's lots of experimentation going on with this trailblazing effort. But it’s really my only option at this point given my physical condition I have briefly explained. VTPR is still in my blood.

Do you remember the old saying TWITT, The Wing Is The Thing? Well the wing on this ship is quite different in construction, and it’s a new thing for long-span VTPR aero. Predicting she will fly and I will perform well on the sticks after 6 years on the sidelines, this new “foam board wing” design will teach us more. I’m hopeful of a positive result... Currently there is only one pilot on the planet that I have seen close but not fully doing electrified PVTPR. Why only one? Well it’s darn dangerous without slope lift in dead air right? Nobody does VTPR over a flat plain with gliders and no lift for extended periods of time! So nobody really possesses the skills yet except 3D power-plane pilots, although we did a ton of overland flying into the wind low in the LZ at Glider Point. And let’s be frank, most slope pilots aren’t really interested nor would I if I weren’t semi-crippled. On the other hand if you are one who is a little older and a little slower, and tired of climbing hills, you might sense gliding aerobatically with the absence of wind shears, sudden loss of lift and all the incidental conditions the slope throws at you has a certain attraction to it. I myself prior to my physical limitations never considered PVTPR until now.

This flying style will require more precise stick control, greater inertia management along with prop speed management in the middle and out of the figure to set up for the next approach into the V zone. It’s quite attractive actually if you think it through. And it’s fresh… You can learn more about PARK-VTPR here.

Hope you climb on board as a watcher and a builder/flyer too. Your contributions to this glider flying type will surely help advance it into a very fun, economical and exciting type to fly and enjoy. Shall we get started building this thing?

Eric,
VTPR Aerobatics
Last edited by oldscooler; Mar 10, 2019 at 06:49 PM.
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Dec 27, 2018, 02:14 AM
What you looking' at fool!
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I'm in
Dec 27, 2018, 07:30 AM
Registered User
For those wondering what does VTPR stand for...
Dec 27, 2018, 10:03 AM
vtpraerobatics.blogspot.c om
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What is VTPR


Quote:
Originally Posted by renatoa
For those wondering what does VTPR stand for...
A little more simple and concise description of the VTPR (very close to the ground) type on one page. Thanks E.

http://vtpraerobatics.blogspot.com/p/blog-page.html
Last edited by oldscooler; Dec 27, 2018 at 03:57 PM.
Dec 27, 2018, 02:03 PM
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The Concept


The plan-form dimensions are based on a French designed VTPR model, LE SONIC. There are a couple differences due to the tail feather arrangement but overall this is a solid beginning point for 2.5 to 2.8m wingspan. You might ask, Why such a long wingspan? Simply, more square inches for low wing loading in a no lift environment. And a more majestic in your face presence of the glider. We don’t want to have to zoom around at higher speeds all the time just to stay aloft. There is a certain “floatiness” designed into this glider to abate most of that. My target ready to fly AUW is sub 50oz. A large departure from the Slope version to this Park version is the fuselage style. I am utilizing a very light (7oz) AVA F3J carbon reinforced fuselage assembly simply for the weight savings, and less parasitic drag for dead air efficiency. In the park or plain there is no need for a heavier, more bulbous and taller (fish like) profile fuselage as there is not enough upward lift within 20-30ft of the ground where this ship will primarily be flown. And besides, my fuse selection just looks better imo

Tail feathers are all constructed of 3/16” balsa with carbon reinforcement. It will have a large elevator pitch control versus the heavier flying stab arrangement. And a large rudder for low speed aero. There will be no flaps, just 2/3 span large chord ailerons with gobbs of throw utilizing maximum expo. Snap-flaps will be mixed in the ailerons as is typical of VTPR mixing set-ups. There will be no “mad flight” controls on this prototype.

The wing is a foam-board construction for a couple reasons. 1) I have always wanted to do a larger tapered glider wing with FB to see how it would form and hold its shape. 2) Its inexpensive and easy to fix or make another panel in quick order. 3) Its much less time consuming versus a white foam veneer wing panel. I love veneered wings and may even build a set for the purpose of this type of glider, but we really want to see how FB in symmetrical airfoil will perform before we move into another wing design.

Motor drive is initially going to be an ART-1700 out runner installed in a removable nosecone assembly. Static thrust is 61oz running 26-34 amps @ 850rpm. Prop will be a 12.5x6.5 folder. Provided the balance point on the model with this gear turns out without adding nose or tail weight, I think this combo will be enough to maintain decent climb out to 200ft and nice smooth low-level momentum and thrust within the aerobatic maneuvers in horizontal VTPR mode. We will see.
Dec 27, 2018, 02:36 PM
Yes..ok..maybe..lol.....
Watching closely and thanks for doing this.
Dec 27, 2018, 04:39 PM
skumgummi dave
Watching and learning...

Dave-
Dec 28, 2018, 01:15 AM
vtpraerobatics.blogspot.c om
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Wing tests


Everybody has their own approach to beginning a new build. I always like to begin with the wing.

Materials such as white foam balsa veneer, paper skins, monokoted wood wings, EPP foam skinned with NS, 1/64th ply skins over white or blue foam, all of these are pretty common in constructing 2 piece wings between 1 to 4 meters in length. But foam construction board? You know the stuff parents help their kiddos make a school project with. Are you kidding me, really? Yes really, now anyways.

Thinking about the rough and tumble VTPR arena of aerobatics, I’ve always preferred the time tested and proven balsa skins over polystyrene foam design. They are just the best way to form an airfoil right in the hot wire cut beds on a flat bench with my trusty wing press. They are a beautiful sight when done right in the eyes of a craftsman. But, they are time consuming and can be expensive. My first thoughts were “go light and stiff” as you can, and inexpensive and quick. All desirable traits for a new park flying aerobat. Let’s just think outside the box this time. So, I saw some videos on the Armin way of folding foam board and in the beginning they were pretty impressive. Except all of the examples were boring single chord length panels about 30” long max. And they used flimsy foam board strips to make up a so called spar, and they aren't really true-airfoils as advertised. Secondly, they would stack up multiple panel’s inline root to root in order to assemble a 12 foot wing. Well guess what that segmented wing did once the craft was lifted off the ground – the wing drooped over 12 -20 inches at the tips! Just a horrible sight on the ground which straightened out in flight, but guess what again – the wing actually appeared to be flapping up and down like a large bird or hawks wings! This was unacceptable.

So, I thought there must be a way to do longer single panels, and tapered as we like in VTPR or any general slope soaring craft. Long, thin, clean and tapered, and stiff. That’s what I want to make with foam board. I looked and searched all over the globe for a builder who had already done this to help speed up the process. Nothing. Just 30-40” max length and skimpy spars. And basically very ugly and rough looking. That’s not going to cut it with neither my standards nor the VTPR crowd.

So, I took the plunge and started doing some very rudimentary test panels to see if it was something I would put effort in. The first panel I did actually formed up nicely but the airfoil flew upside down. Did another and got it right side up and a little cleaner looking. Then another and I learned how to make ailerons utilizing a full length hinge of the paper skin. That skin is some tough stuff by the way and it hinges very well, I was impressed. Then after a month goes by and I’m feeling more confident, I make a command decision and decide to go for broke and fold a 53” long tapered panel. Well I had a piece of 40” x 30” board in stock and thought; I will extend the board 13” to meet my specification. So I assembled the extension onto the long end using hot glue and the good ole balsa skin joining technique with masking tape on one side and the pieces propped up 45 degrees. Glued it up, flattened the skin on the table and let cool off. Within one minute I have a piece of FB 53” long. Will the joint hold up? Let’s give it a try. Here are some photos of my test panels and the very first 53" tapered single panel to prove the process and learn. It has a 10" root and 6.5" tip. I believe this has never been done until now. Suddenly, I'm getting excited, this will work...
Last edited by oldscooler; Jan 06, 2019 at 03:41 PM.
Dec 28, 2018, 01:46 AM
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Foam Board Airfoil Integrity


Foamboard Symm Glue Tests (2 min 18 sec)
Dec 28, 2018, 02:54 AM
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I would think that if you are not including flaps (either seperate to ailerons or as full span flaperons) at the root you should not use snap flap. If you do you will be including effective washIN just when you don't want it.
Dec 28, 2018, 03:08 AM
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Quote:
Originally Posted by mhodgson
I would think that if you are not including flaps (either seperate to ailerons or as full span flaperons) at the root you should not use snap flap. If you do you will be including effective washIN just when you don't want it.
No we do it all the time actually. It’s a non issue having long ailerons and snap flaps with no inboard moving surface. We only mix in 4-5mm throw on the slope. In the park the mix might be different, we will see. Generally when one is flying aerobatic figures close to the ground any wash-in there might be is really unnoticeable and the result is a tightening up of the glider attitude within an aerobatic curve or turn. They really save you when you need the undercamber both up and inverted.
Last edited by oldscooler; Dec 28, 2018 at 03:24 AM.
Dec 28, 2018, 05:20 PM
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Foam board stock


Next up is the search for large enough foam board to produce a 50” plus panel. Hobby Lobby has it in 60”x 40” pieces having a 0.220” thickness. And they fit perfectly in my Ranger. The paper skins are 0.020” thickness each.
Dec 28, 2018, 08:18 PM
skumgummi dave
oldscooler:

Do you have an item number for that Hobby Lobby oversized foam board? I want to call my local store to see if they have it in stock.

Thanks, Dave-
Dec 28, 2018, 09:20 PM
vtpraerobatics.blogspot.c om
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Quote:
Originally Posted by foamdave
oldscooler: Do you have an item number for that Hobby Lobby oversized foam board? I want to call my local store to see if they have it in stock. Thanks, Dave-
Here you go Dave... they keep it in the back for large picture frame orders. They would only give me 2 pieces at a time but will order for you also.

Eric

https://www.hobbylobby.com/Art-Suppl...-x-60/p/107595
Dec 28, 2018, 09:35 PM
skumgummi dave
Thanks Eric. I'll check it out.

Dave-


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