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Author Topic: Caudron 460  (Read 823 times)
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vtdiy
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« on: December 26, 2018, 09:14:20 AM »

I built a stick and tissue Caudron racer as my first venture into no-cal freeflight about ten years ago. I eventually got a good flight out of it (for me, who had only built and flown a Delta Dart before) with the help of indoor flier friends at our nearby gym. Unfortunately our biggest indoor obstacle, nicknamed "the Skybag" did it in after only two more flights.

I still have the rough plans I drew for the original, and wanted to try it again, but this time in 3mm foam, just to see if it could be done. I changed a few things and made it bigger. Here's where I am so far -- painted and assembled, minus a few more touches, and waiting to receive a motor stick, which I hope to make today. Not the lightest no-cal ever assembled, but I still hope it will fly, the present weight is 8 grams. I'm going to try to roll the motor stick from some light 1/32" balsa I have.

Suggestions for propeller would be welcome. I have read the Cessna 195 thread through, wonderful plane, and I even got a kit for it over Xmas. I don't know if a similar prop would be suitable, since this Caudron is heavier. Or should it be a shorter prop? I also do have some Peck 6" silver props, but I was hoping to do the homemade style prop.

Also, Happy holidays to all!

http://www.sredmond.com/Models/Caudron/Foamdron2.jpg
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lincoln
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« Reply #1 on: December 26, 2018, 09:18:16 PM »

I have a Hellcat nocal that's done very well with a solid balsa prop. You can make them from a block, but I happened to have a blank around. Kind of like this only narrower:
https://volareproducts.com/images/7Sup2Bfree.jpg
I think it was 7 inches. Maybe, with that narrower wing, it would be better to use something slightly smaller in proportion, but if you've enlarged the Caudron to beyond 16 inches, maybe it would be fine with the 7 inch size. If you want to make your own from a block of balsa, this is a good guide:
http://www.gryffinaero.com/models/ffpages/tips/propcarve.html

The size of the prop is related to the size and configuration of the model, not the weight. You account for the weight by using a wider or narrower rubber motor. 

I'm sure you could also use the kind of prop that dslusarc uses in the Cessna 195 thread, though if you've scaled up the wingspan from 16 inches, you should scale the prop up too. One nice thing about that style of prop is that you can make it with a tissue tube hub, which allows you to vary pitch. Just glue in the prop blade spars into the tissue tube with a small amount of Duco ro something. Then you can soften the glue with acetone and adjust the pitch. If the fit is tight enough, maybe you don't even have to glue them in. Pitch adjustment is useful if you don't have a rubber stripper and are forced to use a standard size of rubber.
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vtdiy
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« Reply #2 on: December 27, 2018, 10:52:04 AM »

Thanks Lincoln!

The span is now 16", it used to be 14" until I enlarged it. I did once carve a basswood 6" prop -- so happens that the tree that basswood comes from grows on my property. I have quite a bit of basswood dried!

That prop really flew the plane well, but it broke after a wall collision. I made a second one that broke right away. Our gym is filled with hazards, and the ventilators are not turned off, unfortunately.

So a 7" balsa prop and a 10" prop like the one on the Cessna 195 both would fly well on a 16" span indoor model?

How do you decide what size (7",8",9", 10") would be best to try first for a new indoor no-cal model?

Thanks for your help -- I do appreciate it!

(below: the motorstick was made last night -- I used the Parmodels page as a guide. I hope it's strong enough! I also started to make a prop hanger out of aluminum, haven't tried drilling it or splitting it yet.)
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« Last Edit: December 27, 2018, 12:27:31 PM by vtdiy » Logged
vtdiy
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« Reply #3 on: December 27, 2018, 09:40:32 PM »

I think I've found an answer to the length of a prop for a particular new design in Don Ross's book, Rubber Powered Model Airplanes.

He gives a formula for three classes of models, Scale, Sport, and Endurance. He takes the square root of the wing area (in sq in) and multiplies it by factors 0.8, 1.1, and 1.4 respectively for those three categories.

Taking the wing area of my model Caudron of 52 square inches, the sq. root is 7.2, and for a sport model with a 1.1 factor the prop diameter would work out to 8", and for an endurance model with a 1.4 factor it would be 10".

So that kind of explains the diameter range for me, and gives me a better handle on what size propellor I should use.
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vtdiy
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« Reply #4 on: December 28, 2018, 07:23:35 PM »

Today I made a second nose bearing by flattening a 1' piece of 3/32" aluminum tubing, then drilling two holes 0.22" with a pin vise, and splitting one end with a single edged razor blade. Then I bent the bearing into the usual staple shape with a double bend at one end


I twisted the two split ends with a jeweler's flat bladed screwdriver until an .020" wire could be snapped obliquely into place with a little effort. I used 320 grit sandpaper to clean up the notch a little more so I could easily twist an .020" shaft into place with the other end inserted through the front hole without permanently bending the shaft. Good to go!
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vtdiy
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« Reply #5 on: December 28, 2018, 07:27:13 PM »

I cut out two .042" thick balsa blades copying the blade profiles that came with my Volare Cessna 195 kit. I soaked them in hot water for 20 minutes, and taped them at 15 degrees to a tomato sauce can, and put them by the woodstove to dry.

I had first drawn the blade profiles on the can at the 15 degree angle with a permanent ink pen. It was easy then to line the blades up on the outlines. I think I'll save this outlined can for future props!

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vtdiy
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« Reply #6 on: December 28, 2018, 08:02:52 PM »

The blades were dry in an hour. Unfortunately the metal can left dark oxide marks on the backs of the blades. I'll paint the can before doing another set of props, then reapply the inked profiles.

I cut profiled slits to fit some high quality hardwood kitchen toothpicks I happened to have, and glued the blades to them.
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vtdiy
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« Reply #7 on: December 29, 2018, 04:40:27 PM »

I have a feeling this prop won't last much longer in our gym than the basswood ones I carved a long time ago. But hope springs eternal. I added some tissue set in watered down white glue to the root and tip ends to reinforce the grain a little.
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vtdiy
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« Reply #8 on: December 29, 2018, 10:08:04 PM »

The motor stick with ends fitted and glued. Practice follows the Cessna 195 Nocal thread, bit for bit, except for the motorstick itself which is a rolled 1/32" balsa tube. Motor stick assembly weight so far is 1.0 grams.
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vtdiy
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« Reply #9 on: December 30, 2018, 09:59:06 PM »

I added tissue reinforcement to both hardware mounts and to the center of the motorstick to reduce the liklihood of buckling or seam splitting.

For bonding resin, I used white glue diluted with water instead of the Duco/acetone mix of the Cessna 195 thread. With a kid in the house and in winter with windows shut I like to reduce fumes as much as possible. I think the dilute white glue probably worked as well in this particular application. Total weight of the finished motorstick, ready to mount to the fuselage is 1.1 grams. Length is 11".
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vtdiy
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« Reply #10 on: December 31, 2018, 11:13:42 AM »

I glued the motorstick to the fuselage. I used Gorilla Glue clear, mixed 50% with water to make it foam up, reducing density, and applied sparingly with a toothpick.

AUW so far is 9.8 grams.
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vtdiy
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« Reply #11 on: January 01, 2019, 10:45:46 PM »

I did some glide tests onto the bed, and found I had to add quite a lot of clay -- about 4 grams. Now the prop, and shaft will weigh something, but nowhere near that amount. So I've been thiking hard about weight reduction at this point.

The plane was never intended to be a contest plane, but to try out what I could do with foam to produce a fun flier indoors. Nevertheless, I do want to do my best with what I have accepted as a given construction in this plane. So I'm thinking I should probably shorten the motor stick by an inch. Right now, it is evenly placed over the tested CG location. Cutting off an inch should both lighten the present weight and move the CG forward. It will be somewhat tricky to do this, now that the stick is glued in place. But, live and learn. Next plane will benefit from the experience.

An additional weight savings could be had by tapering the vertical stabilizer on the port side to a knife trailing edge. This would reduce weight aft as well as provide some small right rudder effect, which I'll need anyway.

Likewise I can taper the elevator on the bottom to a knife trailing edge, which will give a slight increase in up elevator effect, which I think may be  helpful, based on the probably conservative decalage I had built in.

Either of these two can be adjusted either way by heat bending if needed, but my hope is they will be helpful modifications as-is.

I might be able to taper the outer lower trailing edge of the port wing panel -- effectively adding some washout there as well. It's not very far aft so it won't have as great an effect as the tail thinning, but it will be a slight weight reduction.

The only negatives will be needing to fill the foam and repaint those areas after these changes, reducing the savings. But they all should reduce weight and tail heaviness, and help tune the plane.

So, that's the plan....
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vtdiy
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« Reply #12 on: January 02, 2019, 02:23:32 PM »

Today, I made a prop gauge using the Parmodels website plan. I made a couple small changes -- I glued the moving gauge piece at the desiired pitch (15 inches) to make it more stable. I found it hard to align the prop well with the moving slider. I can just make a few of these gauges at fixed pitches in the future, as needed.

And I glued a piece of .020" wire vertically at the hub support, as a temporary prop shaft. That also seems to make it easier to get the prop blades aligned, for me. The prop just slides up and off when the glue is dry. (I'm not using a button type prop bearing, as originally intended with this gauge.)

I also used a Parmodels type aluminum tube socket. Because the plane was tail heavy when first glide tested, there's no need to conserve weight in the prop. The present prop components weighed 1.6 grams. Without the prop, and before the airframe mods I'm doing today, I needed about 4 grams of nose weight to balance. That leaves 2.4 grams, which I'm hoping to cut.

Anyway, prop is glued and drying now.
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vtdiy
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« Reply #13 on: January 02, 2019, 03:31:45 PM »

The vertical stabilizer sanded to a taper and motor stick shortened 1 inch. I'll need to paint it. Also the horizontal stab was removed, tapered, and then re-painted. It lost 0.2 grams in the process.

The center of the shortened motor stick is now 1/2" forward of the estimated proper CG location. That means when rubber is added the balance point will move forward.

I still need to taper the outer port wing panel.

Fingers crossed that I may not need to add ballast when the model is finished. It these changes work out I could also be several grams lighter in AUW ....
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vtdiy
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« Reply #14 on: January 04, 2019, 01:00:21 PM »

The Caudron is ready to fly, now. With prop and ballast after glide testing, the model totaled 13.3 grams. Not the lightest NoCal, but the lightest plane I've personally built so far...flyable.....I hope!

I'm going to try to get in a few outdoor trimming flights today if I get a calm. Wind is light and variable. I don't know how winter affects the rubber, so not sure what to expect. Temp is hovering around freezing right now.

I have a short 8" loop of 1/8" I'm going to try 50 winds at first, I guess.

As it looks now:

http://www.sredmond.com/Models/Caudron/Foamdron3.jpg
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vtdiy
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« Reply #15 on: January 04, 2019, 04:40:00 PM »

Mostly calm this afternoon, and I had plenty of time to try it out. It flies, for sure! But trimming is taking me some work to get right. The first problem was, too large a prop for the 1/8" rubber I tried.

This evening I've shortened the prop sticks down and reset the pitch, which will take it from a 10"-15" to a 9"-13".

I did try a plastic Pecks 6" prop and that gave a faster flight with slight climb on 200 turns before running out at about 80 feet across the field.

It didn't seem to respond to the formed right rudder -- I guessed that maybe the fuselage was flexing too much, and the rudder acting like  a servo tab, so I temporarily tack glued a thin balsa stiffener between the cabin and hstab to see if that would make a difference. It seemed to somewhat, but I think the main problem was that I needed more right thrust (and a little less down thrust) at the motor -- at least with the 6" prop. It would glide to the right but fly straight or roll slowly to the left after launch.

I don't know how the 9" prop will fly it yet, glued hub won't be strong enough until tomorrow. Anyway, FUN, actually flying something I put together from scratch!

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vtdiy
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« Reply #16 on: January 05, 2019, 11:48:22 AM »

Rain and sleet today, so no more flying. Plus our club's indoor session was cancelled. Weather report is windy tomorrow with gusts to 25mph. Monday looks like the best chance for more trim flights.
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« Reply #17 on: January 09, 2019, 01:26:33 PM »

Very nice looking Caudron, and I applaud your efforts in getting it to fly. Very cool!
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vtdiy
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« Reply #18 on: January 09, 2019, 02:03:34 PM »

Thanks dohrmc!

We're in for a stretch of real winter cold and high winds for the rest of the week, so outdoor test flights are at an end. Saturday there should be an indoor session, assuming the gym is available.

To catch this thread up to the present, I'd tested the Caudron with a 9-13 prop. I still couldn't get it to climb, so I trimmed the prop to 8". Some improvement, but still a shallow slow turn to ground in about a half circle. I even tried a short length of 3/16: rubber that made it to 3/4 circle. As (good?) luck would have it, it then hit the single ice covered snowplow drift in the field, and knocked the pigtail thrust bearing off the stick. I took it back to the house and glued it back on temporarily with some quick setting epoxy, and this time I decided to add a little upthrust.

Wow, what a difference! Just fifty turns of the 3/16" put it into a couple of 30 foot right hand circles ten feet high. I tried 100 turns then, but it power stalled, so I happily realized I'd be able to go back down in size for the rubber. 3/16" seemed excessive.

I tried a short 1/8" loop with 50 turns and a little added nose weight, and there was still plenty of climb. It was getting dark and I couldn't try it, but I started wondering if I could even go back to 3/32". I'd flown this model for short trim hops maybe 25 times, and it was the first time I saw it climb.

Looking forward to Saturday!!
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« Reply #19 on: January 09, 2019, 03:10:51 PM »

Sounds very promising!  Get it figured out, then once nice weather shows up, wind that rascal up and give it a ride.

I hate to say it, but it’s so cold down here in Georgia, I have a flannel shirt on.
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vtdiy
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« Reply #20 on: January 09, 2019, 04:20:37 PM »

Heh, dohr, gonna be 1F tonight and gusts to 38mph up here. Course we got it easy compared to our Canadian neighbors and I have friends just driving back home east from a 4 month Alaska vacation(?) right now!

I do enjoy watching "Ice Pilots" whenever it gets cold here. Puts everything back in perspective.

Yes, this foam NoCal might just survive my flying skills long enough to get to summer, at which point, if it does, I will wind it up and see what it can do!
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« Reply #21 on: January 09, 2019, 06:40:11 PM »

Hi vtdiy.  Your blue no-cal Caudron 460 looks pretty sharp with that flying prop.   I am following closely - it sounds like you know just how to get it trimmed.  And  "it then hit the single ice covered snowplow drift in the field"  - they always seem to head for those obstacles.   Huh   I am surprised you have any snow or ice at all.    Good luck with the flights!

LASTWOODSMAN
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OH, I HAVE SLIPPED THE SURLY BONDS OF EARTH ... UP, UP THE LONG DELIRIOUS BURNING BLUE ... SUNWARD I'VE CLIMBED AND JOINED THE TUMBLING MIRTH OF SUN-SPLIT CLOUDS ...
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« Reply #22 on: January 09, 2019, 11:08:32 PM »

Thanks Richard! It's going to be tough not trying to fly it with 3/32" the next several days. I'm going to hide this plane away so I'm not tempted to go out in a fake calm, and I've pulled out the board with the Scigs Piper Cub Bostonian plan on it.

I just have the wing to do and the landing gear and it will be, gulp, tissue time on that one. Then if all goes well there, back to the shelved Comet Dime Hurricane. got to do something to wait out this week!
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« Reply #23 on: January 10, 2019, 12:21:42 AM »

Is this plane painted with Apple Barrel acrylic?  You mentioned that brand in another thread.  I just bought some but haven't had much experience with it but I did airbrush some onto pink flooring foam and it seems to do pretty well.  What's nice is the price.  50 cents to $1.25  for 2 ounces at WalMart.

Marlin
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vtdiy
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« Reply #24 on: January 10, 2019, 09:44:55 AM »

Yes strat-o I did use Apple Barrel paint diluted with water for the Caudron. I sprayed it on with a inexpensive Badger airbrush and a small Harbor Freight compressor. Although on R/C models other than indoor/micros I'm more likely to brush it on.

I did a test a few years back of many kinds of acrylic paint, nd their adhesion over time on Doculam -- a difficult surface for paint. Apple Barrel came out ahead of everything else I tried.

Where appearance on block or sanded foam is important, and weight less critical, I fill foam with DAP Lightweight spackle (the kind that feels like the container is empty when you buy it), mixed with a few drops of minwax Polycrylic, some talcum powder (the real talc type, NOT cornstarch), and enough water to bring to a cream-like consistency.

This sands very easily, and is similar to the ages old trick of adding talcum powder to dope to make a sanding sealer for balsa. Raw sanded foam has a much coarser surface than balsa. Lightweight spackle fills those tiny craters with low density filler. The small amount of Polycrylic, hardens it better, and the talc makes it sand smoothly.

On foam sheet -- some like Depron or stripped DollarTree have an acceptable surface finish to begin with, and if you don't sand them, they can take paint directly for a reasonable finish. That's what I did on the Caudron.

The Caudron is necessarily heavier than a stick and tissue model would be, because it is not only painted, but painted on all sides of the fuselage, wing and tail. Besides that added weight, painting a model always puts the paint weight behind the CG, since most of the surface area of a conventional model is behind the CG. That weight usually must be balanced by ballast or heavier construction forward of the CG. So painting makes a BIG difference.

Nevertheless, I like it. Everything is a trade-off. I like having a No-Cal that looks painted on both sides, and I'm not a competitive modeler. I just like the way airplanes look in flight. So this one is personally satisfying (IF I get it to fly reasonably for its weight)

I do admire watching others' beautiful stick and tissue planes hang in the air for minutes at a time, though, it's all good!

I do have ideas for my next foam No-Cal which I think will be functional and weight reducing improvements. But I'm going to complete a stick and tissue model first.
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