ChillPhatCat's blog - RC Groups
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Posted by ChillPhatCat | Oct 19, 2017 @ 12:47 PM | 1,379 Views
No wrinkles!

Cowl needs finishing, Interplane struts need finishing, the starboard aileron is not finished yet, and the forward bottom of fuse and under the wing is still needed to be constructed and the throttle cable is soldered but still need to install the servo... and I have a set of wheel pants I plan to use. I ended up putting a 100 oz servo on the elevator since it was the 5th HV servo I have on hand... miiight be overkill.
Posted by ChillPhatCat | Oct 07, 2017 @ 08:59 PM | 1,574 Views
Took me a while to figure out how I wanted to execute this, but the fairing between the vertical and horizontal stab of this plane, if any of you have researched the full scale or built this piece in scale fashion, it isn't the most simple curve. The fabric on the full scale stretches from the first rib on the vertical stabilizer down to the horizontal stabilizer and there is nothing underneath to give it shape and you have to deal with the curve of the turtle deck and the flat of the TE of the vertical stabilizer. Anyway, I decided to do it in two pieces, and here is my story in pics.
Posted by ChillPhatCat | Aug 28, 2017 @ 11:53 PM | 1,746 Views
Upper wing tips on. Needs lower center sheeting, lower rear sheeting, cap strips and a few more sheer webs. It is very strong and very light... Current AUW exactly as pictured is 42.5 oz. I'm leaving the interplane struts as is but will dress them up on the top and bottom, it doesn't need any torsional strength from an N-strut.

Update: Finished upper wing. Just needs ailerons and lower wing tips recovered and then it will be flyable. Targeting Monday for test flight.
Posted by ChillPhatCat | Aug 27, 2017 @ 11:52 PM | 2,228 Views
Added hardpoints to the center of the wing, aligned and centered the wing. Also made a makeshift interplane strut. I am not sure what to do here, an N brace doesn't look quite right. I may make a more modern strut or maybe just leave it like that and match with the other side. The plane is sitting at 40.5 oz with battery, prop and ESC tossed in. I don't think there is more than 4-5 oz left to add... looking pretty good to keep under 3 lbs. It's also balancing well with a shift of the battery about 1/2 inch forward.

Also trimmed and re-mounted the canopy.
Posted by ChillPhatCat | Aug 19, 2017 @ 02:09 PM | 2,529 Views
Went down in the basement yesterday after having cut out some ribs the other day... built about 90% of a wing.

Also have performed some calculations. Horizontal tail volume ratio is 0.393 and neutral point is approximately 3.8 inches from the leading edge of the top wing. Going to try and balance at 3.5 inches.
Posted by ChillPhatCat | Aug 05, 2017 @ 04:46 PM | 2,006 Views
Got bored. Maybe it needs another wing...
Posted by ChillPhatCat | Jul 08, 2017 @ 07:01 PM | 19,665 Views
Took off the tape, trimmed up the sheeting, glued it to the subframe and sprayed it all down to set the shape. Should be ready for the last couple pieces in a couple days and then I can remove it from the plane. Oil cooler will have to go on after final sanding and before any exterior fiberglass.
Posted by ChillPhatCat | Jul 07, 2017 @ 11:57 AM | 6,292 Views
Glued on the bottom sheeting for the cowling, sprayed it and wrapped it up with a mile of frog tape. Next I need to cut out for the valve cover and glue it onto the cowl frame, give it a final spray of water to set the shape and then I can pull it off of the plane and do the final sanding and filling.
Posted by ChillPhatCat | Jun 26, 2017 @ 01:30 PM | 3,908 Views
Been plodding along on this still... we've surpassed the year mark on this project but the light at the end of the tunnel has become a point of light in the horizon... it really is starting to look like a Pitts now that I have made some headway on the cowl. I never realized how important the cowl was for a Pitts Special until the last couple days. The plans show a cowl that just extends straight off from the fuselage and completely conforming to the fuselage... but we all know there should be some cheeks on that cowl.

I am not sure at this point if I'll just sand and fill this and paint it or sand and fill and fiberglass, or maybe even turn this into a mold. I think it will end up as some sort of hybrid balsa/fiberglass though. I think a more permanent two piece kind of thing might be good. The valve cover and remote glow plug clip is going to be covered with an "oil cooler"... looks like the proportions won't be totally out of whack either. Overall pretty pleased with how it is progressing.

Also... side note: For a while I was worried I'd have to re-do the joints on the gear, because the right tire was forward of the left... you can see the problem exaggerated in a couple of the shots below. Well after looking at it carefully and drilling some new gear mounting holes, I simply rotated the right side forward and re-mounted that side about half a centimeter forward. It's now imperceptible with a slight toe in on both rather than toe in on one and toe out on the other.
Posted by ChillPhatCat | Mar 12, 2017 @ 10:41 AM | 5,935 Views
I used two 2-56 pull pull cable kits to make these wires... I wanted to use steel wires because these are intended to be fully functional. The way the spars are in my resized plane, not using spruce (balsa instead) and not properly grafted as on the plans but with dihedral braces, I am concerned that they won't be able to handle any aerobatic loading. Now I've got positive and negative bracing. I roughly followed the placing of these wires in the scale location, but only one wire per instead of pairs of wires. The interplane struts just need a little shimming now and the bottom of the top wing needs to be sheeted. The plane now weighs 61 oz without battery or throttle servo. I'm hoping I can keep it under 70 oz all up when it is all done. It nearly balances on the recommended CG as it sits.
Posted by ChillPhatCat | Mar 05, 2017 @ 12:53 PM | 5,626 Views
I built this Cosmo 25 SR back in the winter of '95 into spring of '96 as part of a club event with the Ithaca Radio control Society which I was a member of for about 10 years. We used an old set of plans to kit this plane and met several times in the basement workshop of one of our members and held some kit building classes. And we planned an event for the open house called the Cosmo triflyathon, something we made up for the build... there was a bomb drop event with a cup holding a bag of flower we strapped on the top of the wing, a speed run and another event that escapes me, I think it was the limbo. We also set parameters for a maximum engine size of .50 CI, and you had to start with a pile of stock parts... we ended up with 10-12 complete cosmos. Some low wing conversions with the fuselage flipped upside down, some built stock with the tricycle gear and .20 class engines and a couple guys going for all out speed, one being myself.

I pretty much built the stock plane and reinforced the empennage with 1/32 ply... and of course I bought the cheapest BB .46 I could find, an ASP .46 (on 15% and swinging a 10x7 prop) and I put aluminum gear on with 2 1/4 Hayes racing wheels. My other competition was a low wing Cosmo with a thin airfoil, basically the bottom of the rib profile cut out on the top to fit the wing cradle without mods and a sharp leading edge and a diesel converted BB .25 on a 9x9 prop.

Suffice it to say when we did our speed passes I pulled off 87 MPH and...Continue Reading
Posted by ChillPhatCat | Feb 21, 2017 @ 11:00 PM | 6,193 Views
I stalled for a couple months here hemming and hawing about the cabane struts, I'm just not that good at making accurate bends with wire so I decided to do something simpler. I got some streamlined aluminum tube and used that instead, bent in a simple A shape with 4 bolts for each into hard points inside the fuse. This is a sport scale model so I sacrificed a little of the scale appearance by not following there full scale lines. Oh well. Still trying to decide if I need a cross brace between the two struts.

I deviated in the mounting configuration too, I put hard points into the wing to be able to bolt right into the cabanes. Just need a couple more hard points for the flying wires and to finish sheeting the top wing and tree wingtips then it's down to the finish work.

Oh and the interplane struts are kind of a mess, they need some serious re-shaping, but it's a minor issue. Did I mention how much of a pain the top wing of a biplane is to line up? Oof.
Posted by ChillPhatCat | Sep 30, 2016 @ 02:29 PM | 7,158 Views
I made a push to complete the plane before last weekend but failed. I had wanted to bring this to a local biplane event, but it just wasn't in the cards... well I brought it, but as you can see... not quite airworthy yet.

In my frenzy I made a decision to turn this into a semi-scale Pitts S1C. The only problem in fact is that the lower wing is one bay bigger than it should be to accurately follow the lines, but I figure more wing should probably fly better. I also decided to do a quick and dirty aileron servo install for more accessibility.

I have subsequently finished the lower wing and most of the sheeting is complete on the fuselage. The engine is mounted along with the remote glow plug (a real must with these 4 strokes that have a forward angled plug). I finished the landing gear and most of the cabane struts are sorted out. Still need to finish the second aileron and hinge everything and cover it all. I think I'm 95% done.

Anyway here's some pics!...Continue Reading
Posted by ChillPhatCat | Sep 01, 2016 @ 10:26 AM | 7,824 Views
I completely finished the horizontal stabilizer so I spent some time sanding it and making it nice and smooth and decided to get some inspiration by covering it since it was the first entirely complete piece.

I decided that I'm doing transparent red on the bottom of the plane and solid red on the top and will go with the typical Pitts color scheme: red base with white checks and strips with this being the only modification... I kind of want to remember this build as it's the first in a line of planned Pitts Specials and what better way than to have a permanent peek under the covering? I know solid structures aren't that sexy with transparent covering but I love the depth and iridescence.
Posted by ChillPhatCat | Aug 22, 2016 @ 08:07 AM | 7,421 Views
I had a small issue with the wing joint, the root rib on the starboard wing was angled outward at the leading edge giving the wing a minor sweep. Last night I finally ripped off the band-aid and broke a glue joint to reposition he root rib. Once it was corrected I couldn't resist joining the wings... Also reduces the number of edges that can take a hit of hangar rash.

And of course we all know what happens once you've got most of the final pieces together... Yep, a mock up! Granted, there's no top wing yet but it could fly right? Haha
Posted by ChillPhatCat | Aug 14, 2016 @ 06:23 PM | 6,497 Views
I have been picking away at this project here and there since the last entry and it is starting to really take shape. I added the turtle deck formers and sheeting, test fit the fuel tank, formed the main gear pieces (pic below before I cut the pieces apart) and the forward cabane struts, and mounted the engine.

While test fitting the fuel tank I realized that I had bought an 8 ounce and I had actually intended to buy a 6 ounce. The 8 is a tight fit there so it is just as well. I will be purchasing a 6 ounce with my next purchases. I am waiting on some Sullivan flex gold n rod pushrods to arrive in the mail so I can fit them and then join the bottom wings and fit the mounting hardware.

I am not sure about the right thrust it looks more like 2-3 degrees now that I have the engine on there. I may have to dial it back a tick so I'll have to fly this before I make the cowl which I am planning to do in balsa/fiberglass.

Lots of pics below....Continue Reading
Posted by ChillPhatCat | Jul 08, 2016 @ 11:48 AM | 7,112 Views
First Pic: I finished the bottom of the horizontal stab with simulated ribs, it's a little rough because I put down the edges first and then the ribs, in the end I'm going to sand off almost all of that wood around the edge, if not all of it.

Second Pic: I decided to lay down the ribs for the top of the stabilizer first, and will just fill the edge in later.

Third and Fourth Pics: Added Former F4 up on top which will be just ahead of the instrument panel, I also added plywood doublers for the wing saddle that extend to the back of the firewall, and I trimmed most of the excess wood off of the front and roughly cut out most of the balsa in the wing area, I'll final fit this once the two bottom wings are complete. I have my engine mount arriving today and will soon be drilling and mounting that so I can attach the firewall. The plans say to shim the motor mount for 1 degree of right thrust, but I'm just going to glue the firewall in at the correct angle.
Posted by ChillPhatCat | Jun 30, 2016 @ 08:50 AM | 7,557 Views
In all of my builds to date I have never been able to get the wings done without being distracted by the fuselage. The fuselage is what gives the plane character in my opinion... it's where all the nice curves are and boy do I like curves!

So I had been thinking about the fuselage for a while... I finally broke down and decided that I needed real professionally cut sticks so that everything is guaranteed straight... Turns out the scroll saw is abysmal at ripping sheets (surprise!). Anyway I waited a couple weeks for fathers day when I knew the sticks would be arriving.

I pre-drilled pushrod guides so that they will basically plug right in when I get to that point... pushrods are another thing I tend to neglect and it takes a lot more effort to run them when you do it later rather than sooner. The fuse is built from back to front with the turtle deck floor used to get everything straight. The lower back formers are glued down to the underside of the deck then I used the bottom stringers to stabilize the assembly. The top half of the fuselage sides were then laid down to further bolster the structure. Next step is to work out the lower wing cradle, toss some plywood in the front and attach forward formers, then the turtle deck is built.

On the wing front I did start the wing tip because it makes the wing look a lot more finished.
Posted by ChillPhatCat | May 16, 2016 @ 09:34 AM | 7,271 Views
Built up the basic skeleton of the lower port wing this morning before work. I'm going to have to come up with a better jig... It was a bear to keep this straight. My notches were not so good in the ribs either... Had to fit each rib twice. Using the hardest balsa I had for these spars, in lieu of spruce.
Posted by ChillPhatCat | May 01, 2016 @ 03:39 PM | 10,821 Views
Well the scroll saw is too loud for the rest of the residents during quiet time so I went about this task the medieval way... It was a pretty productive session. The balsa wasn't too bad but even 1/16" ply is brutal. Still there's some sadistic pleasure to be had cutting pieces with a blade. I'm leaving the paper outlines on the balsa pieces until final sanding to make sure I don't lose anything. Next I need to make cutouts in the big formers for fuel tank etc. and I've got to rip a couple sheets of balsa to get 1/4x1/8 sticks... I'm too cheap to buy bundles of sticks.