Pentathlon Evo - Electric
10-15-2010, 03:03 PM
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RE: Pentathlon Evo - Electric
I’ve decided to put a T-Canalizer on the Evo to try to deal with spiral slip stream issues coming off the prop. The idea is to straighten the airflow over the v-stab. I know others are using canalizers, dorsal fins, or other air flow straightening devices with some success on various pattern models. Using a T-Can is a new concept for me as I come from an IMAC world where builds are more scale without these type things. I’ve talked with many people about canalizer aerodynamics, positioning, size needed, incidence setting, etc. and would like to give special thanks to Mark Mendosa and Mark Hunt for their input.
Since I’m not sure what the ideal incidence is for the T-can I decided to make it adjustable. Another requirement was to also have removable canalizer wings (I’ll call them “winglets†for lack of a better term). Having removable winglets will allow the plane to be initially trimmed for proper CG & thrust with just the vertical riser in place. Then when the winglets are installed I’ll be able to tell what impact they have and their effectiveness at different incidence settings.
The construction of a T-can appears simple on the surface, however, making one with an adjustable incidence and removable winglets revealed several problems to overcome. The design of this one is the result of many hours of staring at the plane, staring at other canalizer pictures on the internet, and a 12 pack of beer. I will go into a fair amount of its construction detail across several posts in order to share with others who might be interested. I know there’s always more ways to do something so if you have other design ideas or input let’s hear them.
Since I’m not sure what the ideal incidence is for the T-can I decided to make it adjustable. Another requirement was to also have removable canalizer wings (I’ll call them “winglets†for lack of a better term). Having removable winglets will allow the plane to be initially trimmed for proper CG & thrust with just the vertical riser in place. Then when the winglets are installed I’ll be able to tell what impact they have and their effectiveness at different incidence settings.
The construction of a T-can appears simple on the surface, however, making one with an adjustable incidence and removable winglets revealed several problems to overcome. The design of this one is the result of many hours of staring at the plane, staring at other canalizer pictures on the internet, and a 12 pack of beer. I will go into a fair amount of its construction detail across several posts in order to share with others who might be interested. I know there’s always more ways to do something so if you have other design ideas or input let’s hear them.
10-15-2010, 03:05 PM
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RE: Pentathlon Evo - Electric
Prepping and Sheeting the Winglet Cores:
I told Mark Hunt I was going to add a T-can and asked him for a small set of symmetrical airfoil wing cores. I then cut them down and reshaped them to an 18†wingspan while maintaining the same ratio as the main wings for the root, tip, & length. 18†was an arbitrary span that appeared visually pleasing and is slightly less than the 20†prop diameter which I thought might be important.
The winglets will plug in using 2 halves and will pivot around a wing tube quite similar to most main wing setups. The first issue to resolve was to find a tiny CF wing tube & socket set. This proved to be a challenge with no luck. As a result, a socket was made using 3/16†OD CF tube and the winglet spar tube was made from 1/8†OD CF. The spar tube was slightly larger than the socket ID so it was sanded down to size by chucking it up in a drill press and slowly turning it against fine grit sand paper. Once the socket and tube had the proper fit the winglet tube was cut to a 10†length.
The next issue was how to cut the socket hole in the foam core. To do this a jig was made at the correct height of the foam root area with the core in its shuck. Using the jig to hold straight and parallel a 3/16†OD sharpened aluminum tube was rotated into the core to create the socket hole (see pic). One end of the CF socket was then capped and dry fit into the core to a depth of about 5â€. A sub rib made of 1/8†balsa was then shaped and fit into a slot that was cut into the foam core from the LE toward the TE. This serves as an load distributing anchor for the end of the socket. The CF socket and sub ribs were then glued in place using poly glue. Both winglets were placed in their shucks, joined together by the inner CF tube, and weighted to insure proper alignment. Once dry the cores were sheeted with light weight 1/16 balsa. Balsa LE’s, TE’s and tips were also added.
I told Mark Hunt I was going to add a T-can and asked him for a small set of symmetrical airfoil wing cores. I then cut them down and reshaped them to an 18†wingspan while maintaining the same ratio as the main wings for the root, tip, & length. 18†was an arbitrary span that appeared visually pleasing and is slightly less than the 20†prop diameter which I thought might be important.
The winglets will plug in using 2 halves and will pivot around a wing tube quite similar to most main wing setups. The first issue to resolve was to find a tiny CF wing tube & socket set. This proved to be a challenge with no luck. As a result, a socket was made using 3/16†OD CF tube and the winglet spar tube was made from 1/8†OD CF. The spar tube was slightly larger than the socket ID so it was sanded down to size by chucking it up in a drill press and slowly turning it against fine grit sand paper. Once the socket and tube had the proper fit the winglet tube was cut to a 10†length.
The next issue was how to cut the socket hole in the foam core. To do this a jig was made at the correct height of the foam root area with the core in its shuck. Using the jig to hold straight and parallel a 3/16†OD sharpened aluminum tube was rotated into the core to create the socket hole (see pic). One end of the CF socket was then capped and dry fit into the core to a depth of about 5â€. A sub rib made of 1/8†balsa was then shaped and fit into a slot that was cut into the foam core from the LE toward the TE. This serves as an load distributing anchor for the end of the socket. The CF socket and sub ribs were then glued in place using poly glue. Both winglets were placed in their shucks, joined together by the inner CF tube, and weighted to insure proper alignment. Once dry the cores were sheeted with light weight 1/16 balsa. Balsa LE’s, TE’s and tips were also added.
10-15-2010, 03:11 PM
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RE: Pentathlon Evo - Electric
Winglet Root Ribs
Winglet root ribs were made out of 3/16†light ply. The ribs in the first several pics are rough cut only prior to final shaping & sanding. In order to have an adjustable incidence an elongated tab & slot was used to allow the winglets to pivot & rotate around the spar tube. Both winglet halves are secured by a single 4-40 socket bolt going through the tab slots using rubberized washers and a nylon lock nut to complete the assembly. The initial winglet incidence will be set to zero degrees but will be adjustable to +/- 8 degrees which I’m sure is overkill.
Winglet root ribs were made out of 3/16†light ply. The ribs in the first several pics are rough cut only prior to final shaping & sanding. In order to have an adjustable incidence an elongated tab & slot was used to allow the winglets to pivot & rotate around the spar tube. Both winglet halves are secured by a single 4-40 socket bolt going through the tab slots using rubberized washers and a nylon lock nut to complete the assembly. The initial winglet incidence will be set to zero degrees but will be adjustable to +/- 8 degrees which I’m sure is overkill.
10-15-2010, 03:12 PM
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RE: Pentathlon Evo - Electric
Vertical Riser Socket
The vertical riser was made from a wing tip that was sliced off an old wing core. After sheeting, a 3/16†CF socket was glued in place using poly glue. This socket needs to be perfectly parallel to the main wings socket. Jigs were made by standing up triangular balsa on a base so they could be used to press against the inserted winglet tube to hold an exact position in all axis while the socket glue dried. A laser with 90 degree lines (vertical & horizontal) was used for precise alignment (see red lines in pics).
A hard point was made from a dowel rod with a 4-40 sized hole drilled in it. This hard point was glued into the vertical riser in a position under where the root rib tab slots go so the riser wouldn’t be crushed when the tabs were tightened together.
The vertical riser was made from a wing tip that was sliced off an old wing core. After sheeting, a 3/16†CF socket was glued in place using poly glue. This socket needs to be perfectly parallel to the main wings socket. Jigs were made by standing up triangular balsa on a base so they could be used to press against the inserted winglet tube to hold an exact position in all axis while the socket glue dried. A laser with 90 degree lines (vertical & horizontal) was used for precise alignment (see red lines in pics).
A hard point was made from a dowel rod with a 4-40 sized hole drilled in it. This hard point was glued into the vertical riser in a position under where the root rib tab slots go so the riser wouldn’t be crushed when the tabs were tightened together.
10-15-2010, 03:14 PM
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RE: Pentathlon Evo - Electric
Finished Canalizer & Mounting
These are pics of the completed canalizer. It will ultimately be mounted into a slotted base section of the turtle deck right behind the rear of the hatch. The winglet height will be level with the highest point of the canopy bubble which is just a guess as to where to put it. It can be lowered if needed. The final assembly came to 1.8 ounces (uncovered).
These are pics of the completed canalizer. It will ultimately be mounted into a slotted base section of the turtle deck right behind the rear of the hatch. The winglet height will be level with the highest point of the canopy bubble which is just a guess as to where to put it. It can be lowered if needed. The final assembly came to 1.8 ounces (uncovered).
10-17-2010, 09:56 AM
#60
RE: Pentathlon Evo - Electric
Beautiful work Dean. Some of the complexity is a direct result of my discussions with Dean about adding a canalizer to the Evo. For the record, I prefer the simple vertical flow straigtener for the simplicity of trimming the airplane. However, I certainly do encourage anyone with an Evo kit to modify as desired, whether for looks or other scientific reasons. I advised Dean that it would be best if his Canalizer was adjustable in order to obtain the best incidence for trimming purposes later. Not only has he accomplished this with great craftsmanship, but he has also made it easily removable.
Can't wait to see this one fly with the Q60. Should be great.
-mark
Can't wait to see this one fly with the Q60. Should be great.
-mark
11-12-2010, 07:19 AM
#61
RE: Pentathlon Evo - Electric
ORIGINAL: Fixed Wing
Finished Canalizer & Mounting
These are pics of the completed canalizer. It will ultimately be mounted into a slotted base section of the turtle deck right behind the rear of the hatch. The winglet height will be level with the highest point of the canopy bubble which is just a guess as to where to put it. It can be lowered if needed. The final assembly came to 1.8 ounces (uncovered).
Finished Canalizer & Mounting
These are pics of the completed canalizer. It will ultimately be mounted into a slotted base section of the turtle deck right behind the rear of the hatch. The winglet height will be level with the highest point of the canopy bubble which is just a guess as to where to put it. It can be lowered if needed. The final assembly came to 1.8 ounces (uncovered).
Bob
11-19-2010, 06:42 PM
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RE: Pentathlon Evo - Electric
Here's the air frame all boned up. Ailerons & elevators have not been completed. The canilizer and H-stabs are just taped into position and have not been glued yet. Baffling for the motor needs to be figured out and a few other odds & ends. Then its on to paint & Monokote. As it sits in the pictures with the main gear it weighs 63.4 ounces (3.96 pounds). This is without the motor, batteries, & other guts installed.
12-02-2010, 04:11 PM
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RE: Pentathlon Evo - Electric
The hatch has been painted. It doesn't show as well in the picture as it does in person but the silver area is metallic. It's a little different to work with than straight solids regarding gun settings and spray technique. Thanks go to Bob Sawyer (Sensei) for giving me some tips on how to paint metallics.
12-02-2010, 05:25 PM
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RE: Pentathlon Evo - Electric
Dean can you tell us about how you preped the surface for paint ? What product's you used , glassing , primer etc. Really great looking !!!!
Thanks
Thanks
12-02-2010, 08:19 PM
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RE: Pentathlon Evo - Electric
ORIGINAL: KGSS28
Dean can you tell us about how you preped the surface for paint ? What product's you used , glassing , primer etc. Really great looking !!!!
Thanks
Dean can you tell us about how you preped the surface for paint ? What product's you used , glassing , primer etc. Really great looking !!!!
Thanks
I am not a seasoned painter as this is just my third attempt at painting with a spray gun and PPG. Prior to this I either used rattle can paints or had someone else do my painting. I have discovered that there is an art to painting and the more you do it the better you seem to get. So I’ve sprayed a lot of scraps just playing around to get the feel. Preparation also seems to be critical. Fortunately I had invaluable guidance from both Jim Sheffield and Bob Sawyer for learning how to set the gun’s air, volume & spray patterns and in knowing how to shoot a piece.Anyway, to answer your question, here’s what I did:
1. Balsa surface sanded with 220 grit.
2. Bare balsa sprayed with Auqua Net hair spray. This stiffens and seals the balsa fibers for finer sanding and less epoxy absorption. Any cheap aerosol hair spray will do.
3. Surface then sanded with 400 grit.
4. Surface then glassed using:
a. K&S ¾ ounce weight per yard FG cloth.
b. Pacer Z-Poxy finishing resin thinned further with rubbing alcohol.
5. Surface sanded again with 400 grit.
6. Rattle can automotive gray primer applied. I used Rust-Oleum Painter’s Touch Primer purchased at Home Depot.
7. Wet sanded most off with 600 grit.
8. Rattle can primered again.
9. Wet sanded again with 600 grit.
10. Painted using the following:
a. Finex FX3000 HVLP spray gun with 1.3mm nozzle
b. PPG Concept DCC Acrylic Urethane (color matched)
c. PPG DCX61 Hardener
d. Shop Line JR505 Reducer
e. Shop Line JX101 Wax & Grease Remover
12-03-2010, 07:16 PM
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RE: Pentathlon Evo - Electric
ORIGINAL: KGSS28
Thanks for all the info. I am about to start mine. Did you do any weights after glassing ?
Thanks for all the info. I am about to start mine. Did you do any weights after glassing ?
Primer process added 7 grams
White base paint added 15 grams
silver metallic paint added 5 grams
Total glass, primer and paint added 44 grams or about 1.55 ounces
