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ID this plane and advise engine size

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ID this plane and advise engine size

Old 05-14-2011, 08:15 PM
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vh2q
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Default ID this plane and advise engine size

Getting around to flying my "attic" planes. This vintage balsa plane has 240 in wing area and weighs 24oz dry. It has a standard Cox Bee 049 installed but I think that's too puny, and besides, the thing needs more weight in the nose. Anyone recognize the plane, and any advice re a more appropriate motor? I am thinking of putting an 049 medallion in it, but the RX has only 2 channels so I would have to remove the throttle ring. It needs a firewall mount of some kind.
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Old 05-14-2011, 08:27 PM
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Andrew
 
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Default RE: ID this plane and advise engine size

Looks like a Goldberg Jr. Skylark. The Skylark was designed for a .049 thru .074. A good .049 will fly it, but a NORVEL .061 would give it some zip.

andrew
Old 05-14-2011, 08:44 PM
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Default RE: ID this plane and advise engine size

Bingo, thanks Andrew. However the SL Jr is supposed to weigh out at 18oz and mine (I didn't build it, it came with some garage sale stuff) weighs 24oz!! Part of the problem is the old fashioned 4 AA battery pack. But it's tail heavy, quite badly, so putting in a lighter batty pack won't accomplish anything. I think I have to put a heavier engine in and hang it out a bit further. Not sure what I can do to take weight out of the tail. The stabs are built up not solid. The rudder is solid but thin. I think it's the fuse and a lot of paint weighing it down. The wing assy is very light.
Old 05-14-2011, 09:40 PM
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Default RE: ID this plane and advise engine size

Hi,
I have a fuselage and tail from an old Jr. Skylark. The weight is 5.7oz for the fuse and tail no servos etc. I think that I can reduce that some by sanding the epoxy paint, and recovering the stab and fin. I had an 0.7 in it originally with two 1/2A servos etc. Im moved back to Alaska about then and never got a chance to fly it. I plan to build a new wing with aeirlons. reduce the dihedral and make it full house. With new micro gear i believe that it can be less than16oz.
With a 0.61 Norvel and one ounce tank and throttle it should fly.
RC DOC
Old 05-14-2011, 09:53 PM
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Default RE: ID this plane and advise engine size

I don't think you can find that amount in weight in the colour/covering, that's only going to be a very minor part and not worth the effort on such a pretty and well done job.
You need to be creative with the placement of the radio equipment instead, and especially the battery. A smaller battery can be placed right in the front, below the tank or even below the engine, for instance.
Old 05-15-2011, 08:11 AM
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Default RE: ID this plane and advise engine size


I found the original plans and the balance point is supposed to be 2 5/8" back, which is further than I would have guessed. My plane is actually in balance based on this info. But I think I can put a smaller battery right behind the engine in the "tank bay" where the RX now sits, and move the RX back. Or perhaps I can stuff them both in there, and gain a few ounces.

I think the weight comes from the 2 servos and the battery pack .. the 18oz on the original spec (on the box) has to be with rubber band RC gear.

It's still on the old purple/white wide band which I understand has been "industrialized". I live miles out in the country ... what's the chance of interference? If it flies, I will convert the RC gear over to something newer and that may give me the opportunity to put in a throttle servo. I have a Cox 049 medallion as well as an 049 TD with throttle rings, and then I can put in a tank that will get me round the hayfield more than once.

Old 05-15-2011, 10:39 PM
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Default RE: ID this plane and advise engine size

vh2q'

The radio you have there is a Cirrus Sport Two, open gimbal early 1980s-ish product, the thing is probally AM , and wideband. The case back slides out, and the crystal will have the frq # and band printed on it.

It may have been converted to narrow, but being a attic time machine it is doubtful. Check those batterys for leakage inside the case, if they leaked the radio may be questionable to use, you may be better served to replace it with a newer rig.

That plane looks great, a bit more power would help it fly better, it will probally last for years once you get her setup worked out. Keep us posted!
Old 05-16-2011, 08:01 AM
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Default RE: ID this plane and advise engine size

I've got all kinds of radios, however none of them will talk to the RX in the plane which is on 72.320mhz, and I don't have an RX with the old 3 prong plugs. So I would have to swap out a bunch of stuff and replug the servos. That is phase 2, first just want to see if this thing is any fun. I put a different 049 in her over the (rainy) weekend, with SPI, and I put in a new fuel pickup tube, it was still offset to the side for CL (and rock hard). Had to lose the spring though, my new tubing is too small ID. Hopefully that won't mess up the fuel flow.
Old 05-16-2011, 09:37 AM
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Default RE: ID this plane and advise engine size

howdy Gents, I would look into changing the wheels. The light weight wheels whould save around an ounce to anounce and a half. What servoes are in it now? Could you glue the tail to the fuse? then you could cut off the dowle and lose the rubber bands. Weight is heaver in the tail. Keith.


Old 05-19-2011, 10:19 PM
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Default RE: ID this plane and advise engine size

I put another 049 cox motor into the plane, this one has SPI so I assumed more power. Wrong! Revs, if anything, were lower. I think the motor came out of a car. Perhaps the compression is lower, not sure. Anyway, I then installed a Black Widow with an 8cc tank and that works just fine, quite zippy in fact. I even did an inside loop without trying too hard. The plane moves right along. Plane is surprisingly responsive to that thin sliver of an elevator. Flight time is brief, you have to stay within glide distance of your landing zone after the first couple of minutes flying. But I think the BW is all it needs.

Now if I could just get BW peformance out of some of my (many) "standard" Cox 049s, they would be quite useful.
Old 05-20-2011, 01:24 PM
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Default RE: ID this plane and advise engine size

The tapered stock manufacturers usually shipped for elevators tended to be iron wood most of the time. It may be profitable to make a new one using more reasonable wood.
Old 05-25-2011, 04:55 PM
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Default RE: ID this plane and advise engine size

Sounds like you have a good flyer there, and the Black Widow is just the ticket for it. If it flies good as is, then you probably don't want to mess with anything with the airframe.

Putting a new 2.4GHz radio with much smaller and lighter servos and battery can only help boost the performance.

Hogflyer
Old 05-25-2011, 06:35 PM
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Default RE: ID this plane and advise engine size

Frankly, I don't get the 2.4GHz thing at all. All my planes are still on FM 72mhz (except my ultra long range FPV plane) and FM works just as well as it always has. I fly on a private field so I don't have to worry about interference. So if I convert the plane from AM, I will just go to FM 72, with smaller servos. May go to a 3 channel setup by putting an 049 Medallion in the plane, with a throttle ring and a larger gas tank.
Old 05-26-2011, 07:49 AM
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Default RE: ID this plane and advise engine size


ORIGINAL: vh2q

Frankly, I don't get the 2.4GHz thing at all. All my planes are still on FM 72mhz (except my ultra long range FPV plane) and FM works just as well as it always has. I fly on a private field so I don't have to worry about interference. So if I convert the plane from AM, I will just go to FM 72, with smaller servos. May go to a 3 channel setup by putting an 049 Medallion in the plane, with a throttle ring and a larger gas tank.
Same here, I haven't had a shoot down in years after switching to JR TX's and aftermarket RX's-all that stuff is DIRT cheap now, why should I abandon it?
Old 05-27-2011, 07:15 AM
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Default RE: ID this plane and advise engine size

Same here, I have actually never been shot down from interference. All my radio related failures have been caused by receiver battery or servo issues, neither could have been addressed by 2.4 Ghz. Actually, 2.4 ghz receivers can be even more sensitive to battery health as a voltage drop caused by an over-active servo can cause the receiver to go into "Brown-out" / re-boot and leave you without control during the re-boot process..

On top of that, most of the newer aftermarket receivers have very sophisticated algorithms to recognize your receiver's "signature" and effectively reject everything else.

As for flying at a busy field and dealing with "checked-out" channels, it's better now than it has ever been on 72 mhz! EVERYBODY else has moved to 2.4 ghz which leaves you all alone to hog the 72 mhz frequncy of your choice all day long

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