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Author Topic: Checkala Roma project  (Read 1342 times)

Online jerry v

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Checkala Roma project
« on: September 14, 2021, 12:47:46 PM »
It all started at 2021 NATS. I met Joe Gilbert. I was inspired by his abilities to fly  any model any time and remember different pattern routines. I was practicing intermediate stunt and Joe was practicing OTS with his Ringmaster on the neighboring circle.I started to think flying OTS too.
When I was at the flying field of our home club after NATS, we practice PAMPA stunt with John Ward, our club member. During the time of rest and discussion I told him about my interest in OTS flying. I have a Nobler and a Ringmaster, both electric. And then John told me the story of Checkala Roma - first stunt model with symmetrical airfoil, about the 13 year old boy who flew inverted and was a winner of the Walker Cup for three years on a row, 1946, 1947,1948. And also about the song.
When I looked up the information about model Checkala Roma, pictures and prints, I wanted to build it.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #1 on: September 14, 2021, 01:45:50 PM »
John Ward and I agreed to build this model. John will build it in the conventional way like original- balsa, ply, silkspan, glow engine ( maybe spark ignition). I decided to build Checkala Roma electric, and make it from foam, and cover it in the silkspan and white glue. It was the first week of August, and I was thinking to finish the model to participate in OTS during Bob Huntís Snow flakes event in the first weekend of October. Itís faster to build model from foam. John printed the plans and presented it to me on August 2nd . Thanks, John, now I owe you!))
I decided to make a wing first. I have enough white stucco foam size 3x24x36 inch.
All templates I made from .008 in sheet aluminum. Itís easy to cut and it works. Remember- I want to build as fast as possible to see how it will fly. And appearance was secondary issue.
Usually I trace the plan to the printing paper, adhere the contour to the folder or cereal box, cut it out, trace to aluminum, and usually itís more accurate templates- left and right.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #2 on: September 15, 2021, 06:47:11 AM »
Checkala Roma plans show wing chord approximately 9 inches. Donít know if plans have been scanned from magazine pages? But lines are thick)) Wing will be 9 in (228.6 mm$ wide and wingspan is 48 inches. Area is roughly 400 sq inches. My target flying weight planned to be around 40 ounces. Power - Cobra 28/20/12 970 kv electric motor, 4 cell 2200 mah lipo battery, 11x5.5 APC prop, 40 amp ESC and FM -9 timer. Power equipment is at least 15 oz, so the rest of the airframe should be around 35 oz. If I will make glow power it will be OS. 25 LA or FP.
The beauty of the foam cutting is once templates made, itís very tempting to make more models in the same time. I decided to build two models simultaneously to pick the lighter one for electric and the other for glow or spare/ experimental/ science)) My brother is not just software genius, he is also RC helicopter pilot, and he likes to create electronic gadgets. He built the transformer for foam cutting, 12/24 volts variable, and I made a nice box for it. System uses .015 wire and cuts any size foam , once I cut 30 inch long wing panel. Checkala Roma wing halfís are 19 inches long, and the wing tips are 5 inches long. So settings are for 24 inches wide cut.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #3 on: September 15, 2021, 06:55:58 AM »
All templates are sanded together to shape and drilled for .070 diameter finishing nails to be pinned to foam. Locations are by the width of the foam block, and templates for profile, spars , lightening openings are using the same holes for pinning to foam.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #4 on: September 15, 2021, 07:05:42 AM »
I cut extra wings o practice. And cut one piece 21 inches long for the wing tips. Spars slots are made on all pieces.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #5 on: September 15, 2021, 07:18:01 AM »
All templates are dimensioned from the bottom of the 3 inches thick foam block, all work is done on the glass table top . Glass is 3/4 inches thick and square with 31 inch sides.
Next is to make hot rod opening for wire cutting lightening holes. With precision hammer and chisel I made a block with the different size ďVĒ grooves. Use my kitchen for science.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #6 on: September 15, 2021, 07:28:47 AM »
Disconnect one side of the hot wire, slide wire trough the melted hole, connect the wire to the cutting frame, adjust current to cut slow, an voila! Weight is 29 grams.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #7 on: September 15, 2021, 08:40:00 AM »
Original Checkala Roma model had very small bellcrank spacing 2 1/8 inch and non adjustable leadouts. It was very tempting to build my Checkala Foamie with no adjustable leadouts too. Just drill the foam wing tip and glue the aluminum tube cable guide. But itís to simple, and we like the science and variety. So I decided to put 4 in belcrank and make adjustable leadouts. In the beginning I wasnít sure about strength of the 15% wing (1.350 inches thick), so I made wide spacing between lightening holes to have a stronger wing. Wing has no taper, itís rectangular shape, and itís easier to make two separate leadouts guides, even if itís heavier.
Templates for wing tips traced, glued to yellow folder cardboard, cut out, traced to aluminum and cut with regular scissors.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #8 on: September 15, 2021, 08:48:08 AM »
21 inches long piece of the wing with no lightening holes was sliced in 4 blocks.
Aluminum templates on top and bottom, pinned with finishing nails.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #9 on: September 15, 2021, 09:02:03 AM »
Hot wire tool is 4 inches fork with.010 wire, from the hobby store. First I cut wing tip ďtipĒ 4 inches away from the root, but it was not enough room to make slider components to fit, and top surface shape wil open the hole to the lightening opening hole. So I made cut later at 3 1/2 inches away from the root. Lightening openings have been made with the same templates, just outer template was shifted toward the spar, to make more room for front cable guide.The hot rod is very useful too.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #10 on: September 15, 2021, 09:07:56 AM »
Continue
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #11 on: September 15, 2021, 09:16:35 AM »
With precision hammer and chisel I made the line guides. Sliders are 1/16 plywood epoxied as a double to make 1/8 thick slider. Itís 3/8 inches wide and slot is 1/8 inches +. Screw is 4-40.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #12 on: September 15, 2021, 09:22:41 AM »
Slider glued to the 1/64 plywood and epoxied to the tip.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #13 on: September 15, 2021, 09:58:28 AM »
If I will make the tip of the wing tip again on the foam wing, I will use Depron. But for now itís balsa, and itís heavier. Make a sandwich of the 3/8 x2 balsa and 1/8 space for Allen wrench. Epoxied to the existing slider, and plywood face . 4-40 Screws blue lock tighten and buried forever.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #14 on: September 15, 2021, 11:28:07 AM »
Because wing will be slides trough the fuselage sides, and for easier way to work with wing assembly and finishing I decided to make belcrank installation as the last operation. Also the belcrank have to be removable for science to use different line spacing- from 4 inches to 2 1/8 inches. With removal cables have to be cut and wrapped again.
The best glue to use on the foam is the same density as a foam. But Elmers or carpenters glue cures for tooo long.
I used 5 minutes epoxy applied with sponge.
Bottom wing cradles against the straight edge on the luang flat closet door . First glue the wing halfís, and wing tips after.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #15 on: September 15, 2021, 11:43:54 AM »
Wing on the glass top, leading edge against the straight edge. White gorilla glue applied very  little, it expands, and itís hard after 1-2 hours. I used spruce spars 1/4x1/8 x 48 inches. It can be balsa 1/4x1/4, it will be easier to sand to shape and lighter. Masking tape over the spars and a lot of weight on top of the sandwich. Whilst gorilla glue is curing, lightly sand the trailing edge and glue the TE balsa 3/16x3/16. I used 5 minutes epoxy.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #16 on: September 15, 2021, 11:57:16 AM »
I used 48 inch long T stock aluminum bar with 180 grit sandpaper to sand the flat area on the foam leading edge. And on the glass table with straight edge I epoxied the balsa LE strip 3/6 x5/8x48. Pinned in place  on the centerline. Now two wings will be sanded to final shape. Wing with numbers 56 is heavier than 32, because LE balsa was harder.

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #17 on: September 15, 2021, 01:02:35 PM »
To fill imperfections of my previous work on the wings I used 3M patch plus primer compound. It is to hard, but I used because I had it already for home)). It does sands ok, fills up the sandpaper quick. Itís pretty light too. After sanding the filler wings with no belcrank are 4.55 and 4.76 oz ready to cover.
At the beginning I was planning to use 50/50 Elmers glue wit water and green masking paper, widely used in the automotive paint shops. Paper is cheaper than silkspan. But silkspan is stronger and soaks much easier.
First covering was heavy silkspan with Elmers 50/50. I rolled the glue over the silkspan on top of the plastic garbage bag. Then applied the soaked sheet to the dry wing surface. Heavy silkspan is a very easy material to use in this process. Smoothed out with my hands, ripped the extra paper, added some glue on the edges . Did only one half of the wing on the bottom, then turned over and did the top. So it will dry and not be warped. Same procedure after, to cover the whole wing. Weight after dry 5.43 oz and 5.67 oz (I make two sets of wings)

Jerry
Variety is the spice of life.

Online jerry v

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Re: Checkala Roma project
« Reply #18 on: September 15, 2021, 01:21:43 PM »
To make surface harder I decided to apply one coat of the medium silkspan on top of existing heavy silkspan. Same procedure, weight after drying 6.24 oz and 6.45 oz.
After that I decided to apply one coat of the polycrylic water based clear. Elmers glue is dissolving very easy, it needs some sealer. After drying clear coat weight was 6.59 oz and 6.87 oz.
The future plan is to paint the model with the water based acrylic latex enamel.

Jerry
Variety is the spice of life.

Offline Ara Dedekian

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Re: Checkala Roma project
« Reply #19 on: October 27, 2021, 05:36:14 AM »


     Hello Jerry

         Your first post about building the Checkala Roma and the thirteen year old boy who flew it was of interest to me. The thirteen year old boy was Davis Slagle, who ended up living in Maine and who I became very close friends with. Dave disappeared from the modeling community after his three Walker Cup wins but never gave up modeling. Below is his RC design he named 'Bippi' (his infant daughter's pronunciation of 'biplane'). In his final years, Dave was cranking these out one after the other. Dave's hot doggin' skills stayed with him right to the end. They were so lightly built, and so overpowered they didn't last. His motto was, 'you don't repair them, you build a new one'. I also have a C/L Bippi that Dave built which I flew at the last Brodaks. Owning and flying Dave's planes is pretty special. It's truly an honor.

          I told his daughter about your project. She and her family were happy to hear that her dad's legacy lives on.

     Ara

Online jerry v

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Re: Checkala Roma project
« Reply #20 on: October 27, 2021, 07:09:56 AM »
Ara,
Thank you for sharing details about Dave Slagle!
In the beginning of this tread I mentioned John Ward, who inspired me to build the Checkala Roma project. I was building this model from foam. John was building it in traditional way, from balsa and plywood. He was making everything as close as original. I decided to go with electric  power. John decided to use OS .35 FP.  John now is far ahead of me on finishing his model. He shared the pictures with us, and I post them here:

Jerry
Variety is the spice of life.

Offline Mark wood

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Re: Checkala Roma project
« Reply #21 on: October 27, 2021, 12:20:11 PM »
Very cool project on so many levels. Thank you for sharing.
Life is good AMA 1488
Why do we fly? We are practicing, you might say, what it means to be alive...  -Richard Bach
ďPhysics is like sex: sure, it may give some practical results, but thatís not why we do it.Ē Ė Richard P. Feynman


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