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RCM Plans Corkscrew

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Old 01-31-2011, 01:05 PM
  #26
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Default RE: RCM Plans Corkscrew

Since mine was 8% larger I went with the 5/32 wire. I've got a Dubro wire bending jig which helps somewhat with the bends, but it still is a guess and a redo sometimes. You are making progress........excellent. Garyss
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Old 01-31-2011, 09:49 PM
  #27
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Default RE: RCM Plans Corkscrew

Had to make a hobby shop run today to gather a few things I needed for this project. I scored on most of the needed items but since the shop is 60 miles away, I lost valuable building time. This evening I epoxied some plywood in the tail, then mounted the Sullivan tailwheel bracket. Did some minor trimming of the tail pieces and mocked them up with tape. They are now ready to bevel the control surfaces, final sand, and cover. Also test fitted the new aluminum backplate spinner. I like it.

The hobby shop had their Flyzone Albatroses on clearance for 1/2 price($40), so I couldn't resist picking one up. I painted the tiny pilot bust and cockpit area. Can't wait to fly the little thing but bad weather is heading our way tomorrow.
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Old 02-01-2011, 05:56 AM
  #28
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Default RE: RCM Plans Corkscrew

I'd tell you to poke through the "Indoor and Micro", "Micro RTF", and "ParkFlyer" forums over at RCGroups for extensive discussions about the Albatross, BUT that would take you away from building on the Corkscrew so I won't.
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Old 02-01-2011, 09:40 PM
  #29
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Default RE: RCM Plans Corkscrew

The freezing weather has finally made it all the way to the Texas coast. Too cold to work in my garage/shop so I had to move some stuff inside the house to continue. Since I start working night shifts tomorrow, I plan to stay up all night tonight covering the ailerons and tail pieces.

Current temp 28F and falling.
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Old 02-02-2011, 10:09 AM
  #30
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Default RE: RCM Plans Corkscrew

Stayed up late covering the small bits.
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Old 02-06-2011, 01:23 PM
  #31
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Default RE: RCM Plans Corkscrew

Over the last few days I finished the torque rod/trailing edge assemblies, then drilled and notched the ailerons to accept the torque rods. Wings almost ready for cover.

Installed rudder and elevator control horns, cut the pushrod exit slots in the fuse sides, and sheeted the fuse bottom. I'm using Sullivan Gold-n-Rod pushrods instead of the dowel rods shown on the plans. No real reason, it's just what I usually use.
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Old 02-07-2011, 08:49 AM
  #32
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Default RE: RCM Plans Corkscrew

Great progress!

Reminder: make sure the tail's control rods are rock solid as you will be doing lots of snaps and spins with this one (don't want any blow by or flexing under stress).

With mine the persistent maintenence items were (1) the covering areas on the wing TE where the rubber bands came across and (2) keeping the covering tight on the right side where the exhaust goo collects in the wing/fuselage seam.
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Old 02-07-2011, 04:05 PM
  #33
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Default RE: RCM Plans Corkscrew

Thanks, Gary. You're right. I do indeed plan on wringing this thing out with full control deflections at high speed just as Stu Richmond discusses in his build article. I'll be sure to brace up the pushrod sleeves.

Wing covering is in progress.
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Old 02-08-2011, 04:37 AM
  #34
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Default RE: RCM Plans Corkscrew

Wing covering is done.

Got the servos and rails mounted. Using standard Futabas for the control surfaces and a HS-65 metal geared micro for the throttle. Routed throttle cable sleeve.

Cockpit top plywood sheeting going on.
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Old 02-09-2011, 08:41 AM
  #35
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Default RE: RCM Plans Corkscrew

I had a tough time figuring out the servo and control linkages. Had interference issues with the aileron rods. After a lot of tinkering and headscratching, it is all working without binding or hitting anything. I'm glad I left the top sheeting off so I could look through the bulkhead and check for free movement. Attached the pushrod sleeves in several places with glue or epoxy to make sure they wouldn't move under a load.

I used offset in the servo horn to establish aileron differential(more up than down).

Made a neat little throttle cable guide from spruce.
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Old 02-10-2011, 04:48 PM
  #36
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Default RE: RCM Plans Corkscrew

Finished sheeting the fuse and made the plywood doublers that protect the wing from the rubber bands.



Here's the latest mockup. Now I've got the flu and am supposed to be working a lot of overtime over the next week or so, so the build updates will probably go on a temporary hold. [&o]
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Old 02-19-2011, 02:31 PM
  #37
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Default RE: RCM Plans Corkscrew

Tee Bee, Hope you have gotten well! Take care............
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Old 02-19-2011, 06:09 PM
  #38
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Default RE: RCM Plans Corkscrew

Thanks, Gary. All better now. Got the wings finished last night and the fuse prepped for covering. The aileron hinges have been glued and now they go flip and flap. Busy working overtime now but am hoping to cover the fuse next weekend.
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Old 02-20-2011, 07:05 AM
  #39
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Default RE: RCM Plans Corkscrew

Springs coming.......or maybe it is already in Texas[8D]
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Old 02-22-2011, 07:19 AM
  #40
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Default RE: RCM Plans Corkscrew

one guy in our club had 4 of them, the last one was powered by an old Skyward .40, ind I even built one and used a ST G.34
Great little planes, a blast to fly and small enough to stick in the car.

Bill
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Old 03-01-2011, 10:05 PM
  #41
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Default RE: RCM Plans Corkscrew

The spring weather was here today with a high of 72F and blue skies. Did a little rc flying and it was great.

I've been off work the last several days and was able to get some work done to the Corkscrew. Covered the fuse, epoxied the tail stabilizers on, made and installed the tri-stock gussets on the vertical stabilizer, hinged the rudder and elevator, installed the pushrods, sealed the bare wood areas with finishing resin, epoxied the dowels in, and painted the landing gear wire. It's getting close now!
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Old 03-02-2011, 07:45 AM
  #42
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Default RE: RCM Plans Corkscrew

Yeah, that is going to be a good rendition.
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Old 03-02-2011, 03:19 PM
  #43
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Default RE: RCM Plans Corkscrew

She's coming together. Got the throttle setup today and mocked it all up for some pics. Still need to wrap up a few little tasks but it's almost finished.
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Old 03-03-2011, 06:37 AM
  #44
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Default RE: RCM Plans Corkscrew

My congratulations on an excellent model. Great idea using military trainer colors, they work well with the Corkscrew’s lines.

Just for other interested parties:
What was the most difficult part of this build?
What is the estimated final weight?
And what would you do differently now that you have gone through this once?

I have found the Corkscrew handles a fair amount of wind and is an easy plane to fly given the dihedral factor and flat bottomed airfoil.
But knife edge is poor despite what Stu Richmond says. I didn't have a computer radio though for mixing out, but the dihedral and airfoil
are quite anti-knife.

Upright flat spins are a blast.
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Old 03-03-2011, 02:24 PM
  #45
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Default RE: RCM Plans Corkscrew

Thanks, Gary!

This was a very easy build overall. The most difficult part, especially in this era of ARFs and RTFs is spending the time required to cut out all the pieces before construction begins. A scroll saw is VERY handy for plansbuilt projects like this. I wasn't crazy about the wing center section as drawn and decided to join the wings in a more traditional manner of using center ribs and epoxying them together followed by sheeting the center section on the top and bottom(The ribs were cut down 1/16" all around to allow the sheeting to fit flush.). I cut out the servo pocket with a Dremel and mounted it upright but it took some fiddling to get all the pushrods working without interfering inside the fuselage. Overall, I'm happy with the setup now.

I'll have to get back to you on the weight. Don't have scales handy. It seems pretty hefty to me.

As far as what I would do differently, I'll have to let you know after I fly it.

I was hoping for decent knife edge ability but it does indeed look a little "anti-knife".

I can't wait to get this thing airborne soon. It's exciting to fly something you crafted yourself.



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Old 03-05-2011, 01:59 PM
  #46
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Default RE: RCM Plans Corkscrew

Tee Bee!!!!

Very nice job. The Corkscrew has always been one of my favorites. As soon as I can get my life settled down I'll build another one.

I built the larger 80" version and it was a sweetheart from start to finish. I put a gas engine I converted from a weed eater in it and buried the tank in the fuse to clean up the nose. It worked out great. The only thing I'll do differently is figure out a two piece wing and separate servos in each panel.

Again very sweet job and hope you have lots of fun flying it.

Mike
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Old 03-05-2011, 05:11 PM
  #47
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Default RE: RCM Plans Corkscrew

Thanks, optech! I was hoping to maiden it this week but life's been too busy to finish up the last bits needed. I didn't know there was an 80" version. Sounds neat.
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Old 03-05-2011, 05:55 PM
  #48
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Default RE: RCM Plans Corkscrew

http://www.rcmplans.com/index.php?ma...oducts_id=1813

Here's a link, It's called the Corkscrew 80. Good luck on your maiden.

Mike
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Old 03-08-2011, 04:59 PM
  #49
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Default RE: RCM Plans Corkscrew

Initial engine start and break-in. Check

Main needle, low speed needle, and idle speed set. Check

Preliminary taxi testing in the street. Check

Maiden flight. SOON!
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Old 03-09-2011, 08:20 AM
  #50
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Default RE: RCM Plans Corkscrew

It was foggy this morning but it began to clear as the sun came up. I headed out to the flying field to try to get her in the air before the high forecasted winds started.

The plane was already assembled so all I had to do was fuel it and start it when I got there. The .25FX fired right up and was ready to go after a bit of fiddling. Taxied out and lined up with a mild quartering crosswind from the NW. Takeoff uneventful, climbed out and started a high pattern to trim it out. Mostly flew good but it needed lots of aileron trim. Hmmm. Left turns, right turns good but then it got a little twitchy in roll. After a few seconds, the roll control was very sluggish. Almost no left roll ability, sluggish to the right. I got very nervous and brought her down as quick as I safely could. Uneventful landing. Total flight time less than a minute. Noticed that the left aileron wasn't operating, the right was moving properly. Back to the pits for inspection. The left aileron torque rod clevis had come off in flight! During the preflight inspection, SOMEBODY missed that the little pieces of fuel tubing that hold the clevises together weren't in place. I considered myself the luckiest RC idiot in the world, gave everything a good lookover, topped off the tank, and fired her up for another try.

I figured my bad luck had to be over by this point, so I felt confident taxiing out again even though the winds were picking up quite a bit. Another uneventful takeoff and high pattern. The roll control was good and I was happy to have solved the problem. After a couple of minutes of straight and level flying, I brought her in for a touch-n-go. The plane was bouncing around in the wind but came in pretty nice. Back in the air, all was good until the plane started rolling to the left on it's own. It pointed nearly straight down and I thought it was going to crash onto the pit awning but I regained control and was able to pull out just before it hit. All control was regained and I couldn't figure out what was wrong but I wanted it down NOW! A few seconds later, it started rolling to the left again but I was sort of expecting it this time, so when it rolled inverted I gave it down elevator to try to control the decent. When it came back upright, I pulled up. It rolled about 3 times and was out of altitude but luckily it was almost level and upright when it was near the ground so I chopped the power and pulled up to flare it the best I could. It hit in the grass north of the field. When I got to it expecting severe damage, I was happy to find that the only damage was the bent landing gear wire. There's no way I could have salvaged that situation a couple of years ago. Talk about a heart attack!

Back in the pits, with the wings off, I found that the aileron servo extension was coming unplugged from the receiver. It didn't seem to fit very tight and the vibration had allowed it to start working loose. I bent the prongs in the receiver slightly to make it fit tighter, then secured the wires with rubber bands to keep them from coming loose. Then I removed the landing gear wire and bent it back by hand. It was crooked but functional. The winds were really starting to howl but the devil on my shoulder talked me into flying it again. What could go wrong?

The 3rd time was a charm. She flew just fine. All the controls worked as they should and the engine and prop seemed to be a good match for the plane. Shot a couple of landings, did some rolls, 1/2 reverse Cubans, loops, etc. With high rudder rates, it still won't hammerhead for some reason. Didn't try knife edge. The snap rolls were insanely fast. I was consistently too slow at letting off before it rolled too far. I decided to try some consecutive snap rolls and learned that the Corkscrew will enter a fairly flat spin on the 2nd or 3rd snap. Glad I was up high enough to recover. This plane seemed all too happy to spin so I climbed up high, cut the power and gave full up and left rudder and she immediately entered a very fast rotating spin with an easy recovery. Woohoo! Stu Richmond describes this plane's manners as "tortuous" and he is correct. The winds were getting much worse, so I brought her down. When it was flying slow on final, it was dropping wingtips as fast as I could pick them up. Nursed it down to the runway with a few clicks of power. Glad I installed the nylon wing skids since I ground both of them down a bit on that last landing. Too much wind!

I'm very happy with the plane's performance so far. Seems to have some peculiar traits that I will enjoy learning in better flying conditions. This thing wants to spin at the drop of a hat. Definitely not a trainer.

I can't believe it wasn't destroyed today! Other than some crooked landing gear, it looks good as new.

I hope my next maiden is much more boring.
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