RE: Cold Duck - Build
 

That is a very good point and I usually do that. The other challenge is the person taking the video is seldom accustom to using my DV cam! On my Cannon Elura DV cam the mode of the camera must first be changed, then manual focus set and then the focus adjusted and readjusted if zoom is used.

RE: Cold Duck - Build
 

In Gimli, Manitoba, they produced "Gimli Goose".

RE: Cold Duck - Build
 

8178, the very first time I ever got intoxicated (and sick) was on Cold Duck! I would have been around 14, I guess. As I remember it came in little bottles in a beer-like cardboard sixpack carton. Man, the image of that purple snow in the back yard has stayed with me all these years.

Back to the thread. The model looks even better in the air. That is a cool photo where the gear isn't visible.

RE: Cold Duck - Build
 

I expect everyone learned their limits at a young age, fortunately it was Rum for me and to this day it’s not something I miss. But the killer thing about Cold Duck wine is that it looked good, seemed innocent and tasted way too good and caught many off guard! Thus the name “Cold Duck” seemed appropriate for this sleek innocent looking aircraft.

Yes, I sure would have been cooler with the retracts. Maybe another with retracts someday.

RE: Cold Duck - Build
 

Mike,
There's nothing much that Tower can inspire me with either. [:'(] Great job on the CD, it's nice to see a classic design fly again.

RE: Cold Duck - Build
 

The Cold Duck has been flying for over four months now and after a great day of flying it today I thought I’d update the thread.

I’m very pleased with the way it flies. Very light and gobs of power for unlimited vertical and loops as big as you want. It is truly a joy to fly! Everyone that has seen it fly comments on how smooth it is.

Early on I had a problem with the RJL carbs that were on the oldest of the three engines. I put the newest carb on the older engine and it worked perfectly. RJL customer service quickly resounded to the problem and said it was related to the size of the low speed needle valve end. The RJL engine is excellent and their service is superb.

Increasing the horizontal stab and elevator size was a good change and I think it has improved the flight characteristics over the original. It will make very slow, nose high landings that are pretty neat. There is plenty of elevator power.

The main gear was a little bit too long and created too much of a nose down stance and I solved that by reforming the gear wire out further.

At 5 lbs 7.5 oz it is a little light in gusty wind but it is super smooth when the wind is steady. Even with the light wing loading it can be commanded into spins well including easily changing spin direction while in a spin.

My only regret is not building it with tri gear retracts. The extra weight of the retracts would have not been a problem at all.

RE: Cold Duck - Build
 

It is interesting that the power to weight ratio (5.468 lb – 1.8 HP = .0205) of the “new” Cold Duck” is almost identical to a typical 10.5 lb 2X2 ship with a 3.5 HP power plant (= .0208). Of course the typical 2X2 ship will have a wing loading of about 25 oz and the Cold Duck is only 19.3 oz. But I’m not sure if wing loading can be scaled very well because of the Reynolds numbers, e.g. 25 oz on 1000 sq. in. wing compared to 19 oz on a 650 sq. in. wing.

RE: Cold Duck - Build
 

I have been wanting to build this model since i saw it in rcm 35 years ago,I now have the plans and foam cores as well as a set of kdh retracts that match the cas retracts on the plans.the kdh struts are about 1/2 longer than the struts shown but since i fly off grass will go with the extra length and just move the wheel wel.I will be using a hb 61 wth pdp for an engine.I was planning on building this stock per plans but am now reconsidering enlarging the stab and elevater as you did.My question is does the new cold duck fly better than the original due to the increased power and less weight or does the enlarged tail really help.since you flew the original what do you think.I will be using polyurethane and glass cloth for a base for paint instead of monokote and am shooting for a weight of under 6 1/4 pounds.

RE: Cold Duck - Build
 

aerowoof

That is really neat that you’ve been Cold Duck fan for so many years and now it looks like you have all the stuff you need to get a build done. Plus a custom updated on-line build manual by the designer a mouse click away!

I thought it flew very well in 1969 but I always tried to reserve my excitement incase I’d been influenced by my design work. But as others saw it fly they commented on its flight characteristics and encourage me to get the design published.

The larger stab and elevator was worth the effort and improved the elevator power at slower speeds and added no negatives at high speed. With more elevator power it will make very slow nose high landings that are absolutely beautiful. Probably helps the snaps and spins as well. The guys in our club have been impressed with the new Duck’s flight characteristics and one of them is going to build one.

The old Veco 61 in the original didn’t have much power so the K.61 has been like supercharging the power! Probably twice the HP of the old Veco and I would think your HB 61 PDP power would be very close to the K.61. It is a little light in gusty winds at my current weight of 5.4 lbs and I would think it would be a great flyer at 6 ¼ lbs with the HB 61.

I’ve been told that the RCM Cold Duck article was very well received by the readers of RCM and many plans were sold but until the RCU build I didn’t have medium to get much feed back. Although in the early 70s I was on a business trip in Dayton Ohio and stopped by one of the hobby shops and a guy was building a Cold Duck!

I’ve really enjoyed flying the new Duck the last few months and I hope you will too. It would be great if could share your build experience with us on the forum.

RE: Cold Duck - Build
 

ok you have convinced me to go with the large tail,now about making the fuselage 1/2 narrower.i would like to build it as close to the original as possible but since there is a new original I am undecided.leaning towards the revised cold duck mods you presented more and more but doesn't that void the spa legal design parameters?if not then there is no reason not to do the revisions.Thanks.

RE: Cold Duck - Build
 

8178,
forgot to ask, when you made the fuselage 1/2 narrower did you just modify f-2 and f-3 or did you take 1/2 off from the firewall thru f-4?thanks.also when you increased the span of the stab i am assuming that the tip and root chord remained the same?
by the way i will be using and updated Kraft 7Z tx and rx but futaba 130 servos and a 136g on the retracts.

RE: Cold Duck - Build
 

The SPA does not take measurements, so if it looks like a Cold Duck, it is a Cold Duck by SPA rules.

The original fuselage had to be pretty wide to fit the old monster size Kraft KPS9 servos. On the new Duck I took ¼” off each side of F2 and F3 and at the same time moved the firewall (F1) back 1/2” to make room for the longer engine. I left F1 the stock width but made it taller to fit the new space. By moving F1 back ½’ it automatically took care of the width adjustment. The ½” off the width also provides the ability to make the fuselage top more rounded. That all worked out well and retained the smooth lines of the original fuselage.

When I changed the span of the stab I kept the root and tip cord the same width as the plan and added 1/2 “ to the trailing edge of the elevators.

RE: Cold Duck - Build
 

8178,
last night I drew up the new sized formers as well as the othe formers and retract mounting plates in cad,If you want a set pm me your e-mail address and i will give you a copy ,you can check for accuarcy while I wait on my wood order.also if anyone else wants a copy drop me a line did not take much time as they were all straight lines.

RE: Cold Duck - Build
 

have you been able to do knife edge flight with the new cold duck?

RE: Cold Duck - Build
 

With the power provided by the K.61 engine and light weight of the airframe it will pretty well fly any direction you want because the power to weight ratio is so high. I expect the K.61 has twice the power of my old 70s vintage Veco 61s. I sometimes wonder if the fuselage and wing are just along for a ride with the engine. If you have ever flown a 5 ½ pound aircraft with clean airframe that is powered with a strong 61 you can picture how it flies, very fast and ballistic performance. Of course because of the light wing loading it flies slowly very well too. But keep in mind it was designed before knife edge flight was a big deal. Usually aircraft that are aerodynamically good at knife edge have the vertical stab and rudder positioned lower and or centered on the thrust line of the fuselage and look more like the old Eyeball design.

RE: Cold Duck - Build
 

8178, I have read through this entire thread twice and I just can't seem to find the post where you detail the stab mods. If it's not too much trouble, could you point me to the text? This design has been growing on me since I first saw this thread. Thanks, David.

Also, how far back did you move the main gear plates for the tri-gear config?

RE: Cold Duck - Build
 

allow me if you may.
[ I increased the span of the horizontal stab 3 1/2” and the width of the elevators ½”. This change increases the wing/stab percentage from 20% to 25%. When I changed the span of the stab I kept the root and tip cord the same width as the plan and added 1/2 “ to the trailing edge of the elevators. ]

RE: Cold Duck - Build
 

aerowoof, that is correct, 3 ½”.

rainedav,

Measured at the root of the wing, the center of the gear blocks are 5” back from the leading edge. That position is pretty good compromise, letting you rotate the nose gear off the ground at fairly slow speed but there is enough weight on the nose gear for good steering in windy conditions. I fly off tarmac, so ground handling is important.

RE: Cold Duck - Build
 

Thanks, you two. Funny, I went back and looked again and saw the post right away! My eyes must be playing tricks on me.

8178, I've sent you a PM.

RE: Cold Duck - Build
 

Any one that wants a copy of the new cold duck formers in pdf format that you can print out full size on letter size paper e-mail me or pm me.

RE: Cold Duck - Build
 

That’s great aerowoof! Your PDFs should be very helpful.

A note on the Cold Duck Dynamic Balsa wing cores:

On the “New Duck” I built the ailerons into the wing, rather than using the original tacked on tapered strip ailerons that were 1 ½” at the root and 1” at the tip. The new ailerons are 1 ½” all the way to the tip. To do this I eliminated the 3/8” piece on the tailing edge and had to cut a small amount of the trailing edge of the wing off to provide some space for the new aileron width. I made the cut after I sheeted the wing and then I caped the trailing edge with 1/16” hard balsa. The wing tip ended up about 9 1/2” wide rather than the original 9 ¼” and the new root is about 11 ¾”. The wing core is easy to cut with a straight edge and #11 blade. I find taping the straight edge down to the wing with masking tape helps hold it in place while cutting. The new ailerons start 6” out from the root and stop 2” from the tip. With the much higher speed of the new duck it is probably a good idea not to run the ailerons all the way to the wing tip.

RE: Cold Duck - Build
 

Great build thread 8178!! I discovered this thread a few months ago and have read through it countless times. I don't really post that much on RC universe, but I study threads like this daily (no pun intended). However, I thought I'd share a funny / cute story regarding the Cold Duck. About a year ago I bought my then 4 yr old duaghter a Guillows Sky Streak rubber powered model at my LHS. Well I put the thing together in about 2 or 3 minutes (yeah I'm a slow builder). My little girl looks up and says "WOW Daddy - you're a great plane builder - that's a really nice plane, huh?" I said to her "Yeah she's a beauty... kinda reminds me of a pattern ship" as I was rolling the planes fuse betwen my fingers like someone studying an Arresti diagram. "What's a pattern ship Dad?"... So I explained "Oh, they're airplanes that can do tricks like this" ( I zoom the plane around rolling it between my fingers going Zoom Zooooom Zoooom) So enough said about pattern ships and we go fly the thing.

Just the other night (a whole year later), I was drinking a cold brewski and reading through your build article from the 6/71 RCM magazine that my good friend Joe Nagy copied for me when my now five yer old daughter comes out to my garage where I'm reading and says "Wow! Look there's a doggy in that plane!", refering to the dog pictured sitting in the cockpit of the Cold Duck. I said "yeah that doggy's a pilot - nice looking plane, huh?" She looks at the picture of the Cold Duck for a few seconds as I take a swig of beer and she says "yeah... it kinda reminds me of a pattern ship....". I did the ol' beer out the nostrils trick, composed myself and said "Well that IS a pattern ship..." " You need to build one for us Daddy" "That;s a great idea Kyleigh... I think I will build us a Cold Duck.

Ain't kids funny - we hadn't discussed "pattern ships" for a whole year and she comes out with that. Amazing!

Thanks again Mike for the wonderful design and great build thread. Between you and Rainedave, I have some great resources to assist in my future builds. Oh and there's that Joe Nagy guy. He's in your's and Rainedave's league when it comes to building and he lives right down the road here.

Regards from AZ

Todd Ewing

RE: Cold Duck - Build
 

Todd, I just got back from the field after an excellent day of Cold Duck flying and saw your post.

What a great story! Kids are the best. When my son was young I always took him to the hobby shop with me and his reward was a glider or one of the snap together rubber powered jobs. Later on I taught him to fly RC at a young age and it was pretty neat to watch him fly his own Falcon 56. They grow up faster than you can imagine and then you have grandkids to enjoy.

Glad you enjoyed the build thread and the RCM article. The RCU thread was a lot easer to do than the hand written RCM article. No computers back then! My wife helped write the RCM article and I thought she was going to kill me when I kept making changes in the build sequence description. If you decide to go ahead with the Cold Duck build I hope you enjoy it as much as I have.

RE: Cold Duck - Build
 

This thread is amazing! Over the weekend I was handed a stack of '71-'72 RCM magazines by a neighbor who had no use for them. So last night, I'm reading through the June 1971 issue (the ads are great, by the way -- a five-channel Heathkit for $200 with the soldering iron included).

Anyway, "Cold Duck" jumps out at me and blows me away. What a cool, ahead-of-its-time design! Caution, however, on reading the "Schematic for Retract Gear Servo Wiring and and Linkage." No offense, Mike, but it made my head hurt. You pioneering guys did it successfully the hard way. :)

So, I'm reading and re-reading the build article and thinking that simple mechanical retracts would work great and this plane could be built very light for a modern .61. Then, this morning, I search online for "RCM Cold Duck" and find this thread! How cool is that?

Thanks for the great design, Mike.

If any of you guys have that June 1971 RCM, check out the Pegasus, too, and Fred Reese's quarter midget (.15-powered) Cassutt Special. Golden years indeed!

Brian

RE: Cold Duck - Build
 

I joined this forum about a month after this thread was started in 7/05. It was one of the very first build threads I started following. When I got back in the hobby in '05 I could have pursued any direction and I really think it was primarily 8178's building that drew me in to classic pattern. Every other area of the hobby just seemed like a step down after following threads like this.

David