75% Earth Forces Starfighter Centuri #5335

Saluki

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Thanks again, Glen.
I tried to download the decals but it's too big a file.
 

GlenP

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No new progress, just another top view dry fit stack up, the top body support and canopy and nose cones are not glued in place yet. But, just because, I like pictures, don’t you?

4BD80162-C990-4066-858B-A33E421CFB04.jpeg

This type of model is a tough call for what kind of clear coat finish to use. It can really go either way, glossy or matte. Glossy is more sporty and fun, where matte is maybe more realistic and military themed, loosely speaking. When I can’t decide, I just go with semi-gloss or a satin type of clear coat, kind of split the difference. The cardstock really soaks it up, so it takes a lot of light coats to get a glossy finish, and that can add weight which can be an issue for these smaller models.
 
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GlenP

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Final four profile engine fins attached, and top body cross support attached. Waiting for that glue to dry before installing the canopy. I may add some glue tabs to that one to help get it into position and give the glue something more to grab onto.

2C55AEDF-6E17-4D2C-9FD6-6D169ED913C8.jpeg
 

GlenP

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One more dry fit, canopy is just held in place by top body plate, nose cones are just held in by temporary couplers. Just enough to get the idea. Now it’s a party! I mean it this time. Not too shabby for a 2D printed model.

9C06D7C0-1BF9-4230-847F-8DDAF00F7BAC.jpeg

The mini Viper is just under 1 oz it can fly on any 13 mm motor but I would probably not go down to 1/4A for that one. So far the Starfighter is just under 2 oz, I will probably add about 1/2 oz clay total to keep it less than 3 oz, so it will fly on an A10-3T.
 
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GlenP

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I added some glue tabs to the canopy edges to help it seat firmly to the main body plate and upper body support plate. Maybe overkill, but I always had a hard time with edge gluing cardstock and using too much glue that softens the paper before the glue ever grabs. These glue tabs can grab tight with just a very small amount of glue.

68A0437F-1433-4A2A-9D0C-FAFDF6A76334.jpeg
 
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GlenP

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You might notice an error in the Earthforces logo above, I noticed that after I printed this one, but it is fixed in the PDF that I posted. The logo is a mirror image, it should look like this:

Screen Shot 2022-03-17 at 7.46.23 AM.png
 

GlenP

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Canopy glued into place. After bending the glue tabs and making one last dry fit check, I spread light glue around the inside footprint where the glue tabs will go and slid the canopy into position. After checking position, I used a skewer to push down the glue tabs inside from the open end of the canopy in the back, and made sure it stayed in position until the glue set.

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when fully dry I may add a small fillet around the outside edge.
 
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GlenP

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Plenty of room for a 9” chute in each lower body compartment, one is packed in the right side. I have a few of those Jet Puffed marshmallow bags in my parts bin. Now to come up with a horizontal rigging, I may run shroud lines up to the nose cone shoulders and reinforce them for zipper prevention. Somehow I will tie those off to the Kevlar leader line coming from the rear of the body. Going to have to start putting everything on the scale to decide if I want one chute or two. Might look marginally stable here but you do get a bit of base drag behind that body. I am more concerned about total weight than stability.

D68F300C-5252-438D-B3C9-781E2774FF5C.jpeg

I use those in my morning mocha (swiss miss and instant coffee) and tend to collect way too many of those bags. I like the rainbow colors for chutes, and recently made a tube-fin rocket to match a chute made from one of these: https://www.rocketryforum.com/threa...apped-recycle-bin-rocket.169834/#post-2220978
 
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GlenP

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With the two 9” chutes and thick couplers to attach the nose cones this weighs in at 2 oz with the A10-4T engine loaded. So I have a clay allowance of 1 oz, but I don’t think I will need that much. I will add 0.5 oz total, split in equal parts in each nose cone, and see where CG is, hopefully that will be sufficient to pass a swing test. I am not sure how much weight might get added from the clear coat.
 

GlenP

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A detail of the forward shroud mounts. I rolled a thick coupler from scraps for the nose cone shoulder and used a fold over tea bag mount inside that. The glue tabs for the nose are feather cut, and I will attach the nose cones after the tea bags are fully dry. One is shown in place and the other is separate so you can see the tea bag mount inside better.
628D4C94-7AA5-4E6A-814C-87AC42AB2678.jpeg
 

GlenP

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Nose cones are glued to their shoulders, and these are pretty much tight enough friction fit in the body. But after I finish adding clay and white glue to seal it, I will glue them in place permanently.B88E48F9-6AB4-4C6D-9CD2-FD9202CEAEE8.jpeg

just some more rigging to do to anchor the shroud line to the Kevlar and elastic cord and the two chutes. I am using the same spool of outdoor upholstery thread 100% polyester that I use for my homemade chutes. They don’t give a strength rating, but this should be strong enough to survive the ejection force.
 
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If I was doing that kind of build I would have smudges and glue stains all over that white paper.
Are you wearing gloves or are you just very careful? 😄
 

GlenP

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Thanks, folks! Well there are a few little smudges here and there. Not sure if you can see the magazine/catalog in some of the pictures. I use that like a work surface and flip book when I am laying down a glue stick on parts, and am careful to flip to a new page after I apply glue on a part. Also, I put a drop of glue on the magazine, and then use a skewer tip to paint the glue in precise locations. If I get any glue on my finger, or after smoothing a fillet, I wipe it off on the magazine, and then flip to a new page every now and then to have a new clean page. Usually you don't pick up ink from the magazine, you have to be careful with that too. Mostly though, the paper does not need a lot of glue, too much and it gets soft and soggy, so you have to use real light amount of glue and put it where you need it. The skewer tip really helps with that. Also, any glue you get on the printed parts will make the ink jet printer ink run, so you have to be careful with that until you are ready to clear coat it.

A7893FED-3D62-4C5E-900A-E8F5C8D39757.jpeg


with non-toxic white glue, no need for gloves, you can lick your fingers clean!
 
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GlenP

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Horizontal rigging: Kevlar from the back and shroud lines in the front. Elastic cord will go on the end of this Kevlar and to the short engine mount Kevlar leader with a loop for the two chute snap swivels.

1D1173FB-B26A-48FF-8810-384EBAF490D1.jpeg
Now I am kind of worried the cardstock tubes might not be strong enough for ejection loads and might buckle if there is too much tension in those shroud lines when the engine kicks out. I may try to reinforce them along that top crown line before I permanently attach the nose cones.
 

modeltrains

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I may try to reinforce them along that top crown line
Some laminations with or along panel lines sounds like a way to do that.

Hmm ...

This from a resin kit build is interesting,
I practiced a little creative license and added some additional vertical wings. In my opinion it makes this great looking fighter just a little meaner!
 

GlenP

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Some laminations with or along panel lines sounds like a way to do that.
Hmm ...
This from a resin kit build is interesting,
Yes, but I mean on the inside of the body tube, I may add a coupler, or just laminate another strip of cardstock along the top crown line inside the body tubes for some extra compression strength to prevent buckling when the shroud line gets pulled tight.

Those resin models are great, I like that Warhawk ship model. Centuri modified the external lines quite a bit to make a flyable model rocket, might be hard to make a PMC or flyable model from true-to-scale models.
 

GlenP

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I think I am about ready to clear coat.

Because I am a Recovering BAR, Here is the complete recovery harness, plenty of room for all of this in the lower body compartments.
2EE36CA7-3BDE-4CBE-B732-12150FE0F5D1.jpeg

but I am not really a recovering BAR,

I am not recovering.
 
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GlenP

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Here’s how it started:
d8e5ee46-9b4d-4373-8fd0-8dfbe4e40e8e-jpeg.500778

and here’s where it ended up:
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After a few coats of glossy clear, could probably use a few more to get really glossy, but this is covered well enough now.

basically finished, the nose cones are still friction fit in place. One final weigh in with motor and recovery loaded then I will add the nose clay. I will have to glue them in then so they don’t come off at ejection. I hope to keep total weight less than 3 oz for an A10-4t motor.
 
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GlenP

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I have been going through my video footage and am trying to use fast forward for a lot of it. I kind of trailed off at the end and did not record as much video of the final build steps, but I have lots of good pictures. I hope to post a video of this build soon, my first attempt at video recording a build like this, so I hope it turns out okay. I wanted to end with a launch, but not sure when I will get the chance for that.
 

Lee

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What prevents the parachute from falling out during launch?
 

GlenP

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I might rig up a strip of paper that covers the back attached at one edge and tucked into the rear eject engine mount, kind of like the flap in the satellite killer that retains the chute in one of the open side tubes. That would be fairly easy to add to these chute compartments.
 
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