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Old Nov 02, 2010, 12:43 PM
Crash it first, Then fly it
Griffindor's Avatar
The Big Apple
Joined Jul 2008
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I was actually looking at the cub just now, but I originally thought that foam would be flimsier and need more support. Thanks.
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Old Nov 02, 2010, 05:11 PM
Registered User
USA, KS, La Cygne
Joined Jun 2010
143 Posts
I want to build this to use the guts from my busted up hobbyzone champ. Im having trouble scaling it down to the proper size. If anyone has some plans to fit my need i would appreciate it very much.
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Old Nov 02, 2010, 05:21 PM
One of the usual suspects
Vicarious's Avatar
United States, AL, Huntsville
Joined Jun 2007
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Quote:
Originally Posted by miket43 View Post
I want to build this to use the guts from my busted up hobbyzone champ. Im having trouble scaling it down to the proper size. If anyone has some plans to fit my need i would appreciate it very much.
The 12 inch WS was the smallest plan size. But it has been done smaller: http://www.rcgroups.com/forums/showthread.php?t=722083

All Blu-Baby plans listed here: http://www.rcgroups.com/forums/showp...98&postcount=2
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Last edited by Vicarious; Nov 02, 2010 at 05:26 PM.
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Old Nov 02, 2010, 05:26 PM
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USA, KS, La Cygne
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cool ,but i must be blind i dont see the plans for the 12 in. Thanks for the point in the right directions .
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Old Nov 02, 2010, 05:28 PM
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ok.. never mind.. boy that search button works great!!
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Old Nov 02, 2010, 05:33 PM
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12 inches may be to small for my use bummer. i will keep looking
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Old Nov 02, 2010, 06:37 PM
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Omaha Nebraska
Joined Feb 2006
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Quote:
Originally Posted by miket43 View Post
12 inches may be to small for my use bummer. i will keep looking
Don't forget that you can take a plan, say the 33", and 'scale' it when printing (using the printer functions).

33" x 0.6 = 19.8 (0.6 is 60% on the 'print to size option).

18-19" should be great for Champ, spectrum, and other gear. I'd bet even a little larger based upon some home-builts using balsa. Just pick a thin foam, and don't use Blue FFF, unless you want to sand one side down to 2-3mm thick which can be done with 80 grit paper on a long sanding block, before cutting out the parts!

Fred
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Old Nov 02, 2010, 07:08 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,218 Posts
Quote:
Originally Posted by miket43 View Post
I want to build this to use the guts from my busted up hobbyzone champ. Im having trouble scaling it down to the proper size. If anyone has some plans to fit my need i would appreciate it very much.
Looking at the Champ specs:

* Wingspan: 22.4 in (517mm)
* Overall Length: 14.3 in (365mm)
* Flying Weight: 1.3 oz (38g)
* Radio: 3-channel 2.4GHz transmitter with Spektrum DSM
* Trim Scheme Colors: Yellow with orange trim
* CG (center of gravity): Approximately 28mm from leading edge of the main wing
* Prop Size: 130 x 70mm
* Recommended Battery: 3.7V 1S 150mAh LiPo (included)
* Charger: DC 3.7V LiPo charger (included)
* Landing Gear: Fixed main with steerable tail wheel

I think the small BB's of a similar wing span and propeller size that have been built in the past, like the BB 24, were all up in the 3.5 to 5 oz. range and flew with 15 gram or maybe 9 gram brushless outrunners and 2S and 3S batteries.

So I'm not really sure that there is a BB size that will fly with your Champ leftovers. That has a small brushed motor and reduction gear drive but I think the output power is too limited for it fly a plane much heavier than 2 oz. or so.

My son had a Champ and we put a Key Chain camera on it one day (about 25 grams if I remember right) and it was barely able to fly with that much additional weight on it. It did not crash but it did a barely controlled descent to a landing from a hand launch (i.e., very typical of a overload planes/power system).

I welcome your proving me wrong on this, I just don't think the numbers add up.

Jack
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Old Nov 02, 2010, 08:08 PM
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Ontario, Canada
Joined Apr 2010
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Originally Posted by jackerbes View Post
I think the small BB's of a similar wing span and propeller size that have been built in the past, like the BB 24, were all up in the 3.5 to 5 oz. range and flew with 15 gram or maybe 9 gram brushless outrunners and 2S and 3S batteries.
I have a bare 24" BB airframe on the bench. Comes in at roughly 1.5oz. However I use 3/16" blue foam (sliced using my hotwire cutter). By the time you add LG, wing mounts and the lightweight Champ gear you would be hard pressed to stay under 2.5oz I think. If you were to build using normal 1/4" FFF, it would be much heavier.

You are going to have to look at the plane as a whole and shave every single gram of unnecessary weight. But I think jackerbes is right... the numbers don't add up. It's a difficult task to produce a roughly sub 1oz airframe at this size.

Here's another option...

Stevens Aero makes some nice balsa kits specifically for the PZ Ultra Micro gear.... and the gear you have in the Champ is a perfect fit. Have a look:

http://www.stevensaero.com/UltraMicr...p-1-c-336.html
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Old Nov 03, 2010, 05:57 AM
TEAM HILLBILLY
Eagle34's Avatar
Pass Christian, MS
Joined Jan 2010
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Quote:
Originally Posted by miket43 View Post
I want to build this to use the guts from my busted up hobbyzone champ. Im having trouble scaling it down to the proper size. If anyone has some plans to fit my need i would appreciate it very much.
You might try the 20" Oshkosh Special, basically the same as a Blu-Baby. The tail was extended a bit and the wings expanded a bit but its built the same way.

http://www.rcgroups.com/forums/showp...&postcount=437
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Old Nov 03, 2010, 09:58 PM
Crash it first, Then fly it
Griffindor's Avatar
The Big Apple
Joined Jul 2008
536 Posts
Just a quick update. I tested the BB out in the Living room, and taxied a bit, and its pretty good. The wheel was bent, making it taxi left, so I fixed it,, and now it's great
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Old Nov 04, 2010, 08:21 AM
Jack
USA, ME, Ellsworth
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Originally Posted by Eagle34 View Post
You might try the 20" Oshkosh Special, basically the same as a Blu-Baby. The tail was extended a bit and the wings expanded a bit but its built the same way.

http://www.rcgroups.com/forums/showp...&postcount=437
That is a cute little guy, Ken. Was it a fairly mellow flier or a little on the freaky side? Do you remember what it's AUW was?

If the "40 Watts per pound minimum for RC flight" rule has it right, I'd guess the Champs power system to be around 5 Watts or so. I flew my son's Champ some and it was a nice little flier, not over powered but nicely powered. Great little yard flier too if the winds were down.

His Champ went stupid on him a while back and flew off into the sunset never to be seen again. Would not respond to throttle or controls, it just flew away...

Jack
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Old Nov 04, 2010, 08:41 AM
TEAM HILLBILLY
Eagle34's Avatar
Pass Christian, MS
Joined Jan 2010
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Originally Posted by jackerbes View Post
That is a cute little guy, Ken. Was it a fairly mellow flier or a little on the freaky side? Do you remember what it's AUW was?

If the "40 Watts per pound minimum for RC flight" rule has it right, I'd guess the Champs power system to be around 5 Watts or so. I flew my son's Champ some and it was a nice little flier, not over powered but nicely powered. Great little yard flier too if the winds were down.

His Champ went stupid on him a while back and flew off into the sunset never to be seen again. Would not respond to throttle or controls, it just flew away...

Jack
Jack,

I'm not Ken (but he designed it) just posting some information that may help miket43. I found the informaton in the Oshkosh Special thread. Here is another post from that thread with more of the details. AUW was 35gr with a tiny brushless motor, a 1S ESC, and a Full River 250mAh 1s battery. I think that is pretty close to the AUW of the Champ. I've got a micro J3 and it weights around the same (off the top of my head) the Champ is a bit bigger. You might even swap out the Champ motor for one from the PZ UM P-51. I did this in my UM Cub mainly for the strength of the gear shaft (1.5mm vs 1mm) and with a BSDMicro prop adapter and a GWS4030 it really moves. Put a 4530 on it and its a rocket.

Here is the reat of the detailed information.

http://www.rcgroups.com/forums/showp...&postcount=448
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Last edited by Eagle34; Nov 04, 2010 at 11:50 AM. Reason: spelling
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Old Nov 04, 2010, 08:53 AM
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anatoly's Avatar
Falls Church, VA
Joined Jul 2006
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Maidened

I couldn't talk my kid into going out to the park yesterday afternoon, so I decided to maiden the BB33 in the front yard. It's not a big yard, with a big tree in the middle, so I just did circles around the tree to get a feel for how it flies. I was in the middle of a lap when one of the trees on the side decided to step into the flight path, and the BB ever-so-gently landed in some of its low branches. The carbon flats I glued to the LE of the wings helped to prevent any damage.

The first thing I noticed is that it is still quite over-powered with the 10g motor and 7x3.5 prop. I switched to a 6x3 prop and it toned things down a bit, but still had plenty of power, so I will probably stick with that for training my kid.

The second thing is that the wheels and other parts I ordered for my next build haven't come in yet, so I maidened it without the LG. Even with the battery and ESC pocket in front of the LG slot, it was still a bit tail-heavy. I taped a big washer under the nose, then it flew much better. Hopefully I can get rid of the washer when the wheels come in and the LG gets put on.

The third thing is that I didn't have to worry about how the 3.7g servos will perform, because they are doing just fine in this application.

AUW with 10g motor, 6A ESC, 2s360 pack, and two 3.7g servos is 5.6 oz. (158g), before painting. The plan is to airbrush a base coat of white, then whatever accent colors my son wants. Hopefully it won't add too much weight.

It seems that this will make a good indoor/no wind flier, because it really gets blown around quite easily at this weight. Fortunately indoor season is here, and maybe I'll build a larger BB over the winter for outdoor training next season.
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Old Nov 04, 2010, 10:44 AM
TEAM HILLBILLY
Eagle34's Avatar
Pass Christian, MS
Joined Jan 2010
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I just checked on the Horizon hobby site and this is the information I found.
UM J3 AUW 29gr
UM P-51 AUW 34.6gr
Champ AUW 38gr

So the stock electronics from the Champ should be enough for the 20" OKS.
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