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Old Jul 10, 2012, 09:53 PM
Registered User
McCarthy, Alaska
Joined Jun 2004
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Originally Posted by kilabean View Post
The cowl broke off my champ so I Modded it with stale french bread from an old hoagie I had laying around. I had to tape a piece of salami to the tail to balance it out but man that thing flies great now.

Probly don't want to fly in the rain
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Old Jul 10, 2012, 10:21 PM
So broke I can't pay attention
Naples FL USA
Joined Mar 2009
490 Posts
Quote:
Originally Posted by kilabean View Post
The cowl broke off my champ so I Modded it with stale french bread from an old hoagie I had laying around. I had to tape a piece of salami to the tail to balance it out but man that thing flies great now.

That...... just made me squirt a big gulp of coffee right out of my nose, and all over my keyboard!
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Old Jul 10, 2012, 10:33 PM
If it spins, wear it.
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Northern Nevada
Joined Jan 2011
2,260 Posts
Gonna attract dogs, careful
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Old Jul 10, 2012, 10:40 PM
Scout CX | mCX2 | mSR | 120SR
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Canada, AB, Edmonton
Joined Dec 2011
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Old Jul 11, 2012, 12:31 AM
I just need one more plane..
kilabean's Avatar
United States, VA, Fairfax
Joined Jun 2012
142 Posts
Seemed too serious in here I was trying to lighten the mood
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Old Jul 11, 2012, 12:40 AM
If it spins, wear it.
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Northern Nevada
Joined Jan 2011
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Made me hungry and got my dog worked up....
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Old Jul 11, 2012, 12:40 AM
BGR
Foam Junkie
United States, CA, Oceanside
Joined Dec 2003
1,656 Posts
I think its a great idea, if you get real hungry you can just eat your Champ, dont forget the Grey Poupon!
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Old Jul 11, 2012, 01:09 AM
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DeBary, FL
Joined Nov 2010
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Originally Posted by North_of_49 View Post
I'm also working on 2 sets of Champ floats... one from scratch using the plans available here at RCG and one from modified Carbon Cub floats (size reduced and hollowed out).
(BTW I still remember your asking about the CF rod 'wing flattener' I just haven't gotten to a pic yet. I want to also find the same angle of a stock wing to show the difference.)

The scaled down CC floats, please please I'm beggin ya please don't do it. If I hadn't already spent a lot of time already thinking about it many times I wouldn't be -repeating- saying this. In a time/reward sense it is simply not worth the effort AS COMPARED to a scratchbuilt set.

If you weren't going to do a scratchbuilt set then I'd say yes it -might- be worth the effort, but there are still caveats.

The scale factor is 15%, comparing 20.5" to 24" wingspan. (Whether 'Champ' vs 'Cub' is exactly 15 doesn't matter all that much, maybe it's closer to 10 or 20, but let's use 15 just to pick a number.)

CRITICAL: To scale this accurately you must reference everything from the step. More correctly, from where that 'inside corner' of the step, where the back half of the float meets the flat surface at the rear of the front half.

From that inside corner, you must scale the upper half down by 7.5%, the lower half 'upwards' by 7.5%, the front half shorter by 7.5%, and the back half shorter by 7.5%.

I don't have a CC float right here but the fuse is 15" and floats are around 2/3 the length of the fuse so let's say the floats are 10".

To scale the 10" length down by 15% that leaves the final Champ float length at 8.5".

OK I'm off by a little, because the jingjingjing floats are 9.25". But those are flight tested not necessarily pure scale. For discussion purposes and ease of arithmetic let's semi-split the difference and call it 9".

EDIT: Rats I'm off again. The *fuse* length on the Champ is 12", 2/3 of which is 8" not 9". But the numbers that follow are based on 9" and I really don't feel like writing it so screw it let's go with the 9. Whether you want the scale it down to 9 or 8 you do the math.

Scaling the 10" down to 9" needs 0.5" trimmed by both the front and back halves. No big problem, just cut it the ends off.

Now here's where the accuracy of scaling it by eyeball-sanding comes in, and how fabulously difficult it is. That 0.5" is to scale the front and back halves of the full 9" down by down. IF you trim off an extra 0.05" (appx. 1/16") you have scaled it down by an additional several %. (At the moment I don't particularly care to do the arithmetic to figure it accurately what the error is.) The point is that do you really think you can lay that foam against a sander, or even use a block sander, and sand it down with 1/16" accuracy? Well, yes, I'll bet maybe you can. But...

But... that' LENGTH dimension is the LARGEST dimension that needs to be scaled down. The width and height must be scaled TO A FINER ACCURACY TO MAINTAIN THAT 7.5% SCALE!! And if the length to height ratio is appx 10-1 the *accuracy* must be 10x higher.

It gets worse... This is all talking about straight lines and flat surfaces. Consider the -curves- of the bottom of the floats, that must be have accuracies held down to the 0.00x" tolerances. Now we're beyond the realm of hand/eye/sanding block capability -within- a reasonable amount of time. Sand off too much and you can't put it back on.

OK now the weight thing. I weighed one CC float, it was 1oz. That's 2oz plus let's say another 0.2oz for the wire. Let's say it's scaled down by 10%, that's 0.2oz leaving 2oz. That's 2oz hung off a 1.5oz AUW airplane. Folks have hung 2 keychain cams of Champs, that's 1oz, they they fly pretty well. But consider hanging 4 cams, 2oz, PLUS the effort of getting off the WATER. It'll get off the water like the Spruce Goose, and handle about as well. (Meaning 'just barely' for each aspect.)

To get rid of the weight let's say you go through the further effort of splitting the floats open and hollowing them out. I'd guess you can save 1/2 the weight easily and 2/3-3/4 with a lot more time/effort. From the 2oz now it's down to 1oz or possibly 3/4oz. Cool. That would help tons, that's reasonable.

I weighed the cut foam for a set of scratchbuilt floats, 0.4oz.. Add another 0.1oz for CA, stiffener, and mounts, total 0.5oz.. The scaled/hollowed floats are definitely heavier than the scratch, but even 50% isn't too extravagant considering they came out pretty light.

Cost: The two 8.5x11" sheets of 2mm Depron cost $0.75, but that's because as I said I'm lucky to have a monster LHS. The spruce and wire add another $0.25, that's $1 total.

So, to sum up, that's a $20.00 set of floats and the time-time-time-time-TIME to do all that fine hand rework to get the kind of accuracy needed, vs $1 plus scratchbuilding time.

Deimos, Phobos, Bottomos, please please don't do it.

I've got a lot of experience in production manufacturing. The time it took me to write this, I could have cut out several sets of depron, spruce, and wire. Drill holes, bend wire and assemble is another 90 mins per set. Time/effort/reward, just do the math.
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Old Jul 11, 2012, 01:41 AM
Scout CX | mCX2 | mSR | 120SR
North_of_49's Avatar
Canada, AB, Edmonton
Joined Dec 2011
7,574 Posts
@jbarchuk

I need to crash, bro... don't have time to soak all that in tonight but will look it over when I'm ready to do it. I like doing stuff like this. I've already considered alot of what you mentioned, in fact, I was going to ask in here soon if my reference when scaling down would be the step or the mounts. Also, I read somewhere the floats should be 75% of the length of the fuse from the prop to the rudder hinges? I'm not going to reduce the size by putting them on my bench mount belt sander like I did when I shaped my foam wheels... I decided I'm going to lap them on sandpaper over flat glass like I do to the mating surfaces of computer cpu's and their heat sinks... will have more control that way. Will use varying grades to get it down in size quickly then smooth them out.

The very first thing I planned to do was chop off the length from the front and the rear to match either jing's floats or the 75% rule... like I said, when doing that, I was first going to ask about that reference point and was guessing the answer would probably be the step.

zzzzzzzzzzzz
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Old Jul 11, 2012, 03:53 AM
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DeBary, FL
Joined Nov 2010
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Quote:
Originally Posted by North_of_49 View Post
I like doing stuff like this.
Understood. I've seen everything you've posted and you get FULL PROPS for being a far better 'scaler' than I am. My only concern with any of this is that it 'works,' and everything else is secondary.

Quote:
the step or the mounts. Also, I read somewhere the floats should be 75% of the length of the fuse from the prop to the rudder hinges?
I *THOUGHT* this reference was where I saw the 2/3 thing but it's not there AAMOF there is no specific % so I'm pretty sure the 3/4 is more correct. Well, a little more can never hurt except when it's adding wasted weight. This ref has step and angle info. http://www.seminolerc.com/float_flying_basics.html

I also found this talking about GP float design/construction but there's some mounting tech info at page 12. http://manuals.hobbico.com/gpm/gpmq1870-1874-manual.pdf

Quote:
I decided I'm going to lap them on sandpaper over flat glass
Yep that sounds *far* more accurate and repeatable.

I was just given a half-destroyed Carbon Cub in the hope that it can be resurrected. Previously, wings had been torn off and repaired. This time only one wing is half torn (hanging on by the paint) but cowl is extremely deformed and fractured. So it's a tossup if I'll scale-up jings plans or get the solid foamies.

I'm mostly decided to use the e-flite floats because they're already the right size, scale, and with mounts. But I have a 'hollowing' question. I've mostly decided that for strength, accuracy, repeatably, and reassembly that the best way to cut the float is a vertical lengthwise cut. But... it takes a heck of a long knife blade to do that. I have a hot wire and could set up a jig to hold it to cut, but get only -one- chance to do it right. What are your plans?

Here's another design for a Champ float yo'd probably like it less because it's less scale looking. It's a flat bottom with a simpler design/fabrication. I guess it's a tossup how much the v-bottom helps with such a tiny airplane. http://www.rcgroups.com/forums/showt...at+pdf&page=35
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Old Jul 11, 2012, 10:03 AM
I just need one more plane..
kilabean's Avatar
United States, VA, Fairfax
Joined Jun 2012
142 Posts
I'm sure you guys already saw this but I'm ordering my floats from this guy for $10. I know most of you want to do it yourself and that is the fun part for you, but I'm too antsy in my pantsy to wait.

http://www.seaplanesupply.com/micro.html

Think I'm gonna ordered the v-bottom instead of the flat bottom... does it matter?
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Old Jul 11, 2012, 10:11 AM
TjW
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USA, CA, Riverside
Joined Mar 2006
220 Posts
Quote:
Originally Posted by kilabean View Post
The cowl broke off my champ so I Modded it with stale french bread from an old hoagie I had laying around. I had to tape a piece of salami to the tail to balance it out but man that thing flies great now.

I hope you never crash it. It will wind up in a million pizzas.
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Old Jul 11, 2012, 10:24 AM
Chris
Canada, NS, Queensland
Joined May 2012
173 Posts
Quote:
Originally Posted by North_of_49 View Post
Just called my local Michaels... they have the Folk Art 627 Tangerine in 2oz bottles for under $2.50 (thanks, airhead!)... am heading out to grab a couple of bottles to try out...
Ok, if we haven't anal-ized this too much, for those who care I'm VERY close to a better paint match. I did it last night and will check it when I get home after work just to make sure it's right in DAYLIGHT and keep you posted. By the way North, that aerial photo of the Carbon Cub ccss_e_13 in beautiful dark yellow /silver is a BEAUTIFUL colour combo - thanks! It goes into my 'scrapbook' along with the orange/silver Waco.
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Old Jul 11, 2012, 10:46 AM
I just need one more plane..
kilabean's Avatar
United States, VA, Fairfax
Joined Jun 2012
142 Posts
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Originally Posted by TjW View Post
I hope you never crash it. It will wind up in a million pizzas.
Haha
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Old Jul 11, 2012, 10:20 PM
Scout CX | mCX2 | mSR | 120SR
North_of_49's Avatar
Canada, AB, Edmonton
Joined Dec 2011
7,574 Posts
Quote:
Originally Posted by kilabean View Post
I'm sure you guys already saw this but I'm ordering my floats from this guy for $10. I know most of you want to do it yourself and that is the fun part for you, but I'm too antsy in my pantsy to wait.

http://www.seaplanesupply.com/micro.html

Think I'm gonna ordered the v-bottom instead of the flat bottom... does it matter?
Yeah, I pm'd him a week ago pointing him to a discussion about his floats being solid as opposed to hollow asking him to comment and still haven't heard from him. There was a discussion somewhere as well as to whether the v bottom was necessary... the answer was that the v bottom was more for the comfort of the passengers in real planes. I asked about it here recently, nobody replied, unless I missed it.
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