Cobra II Z build thread
05-11-2015, 03:29 PM
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Cobra II Z build thread
I have to kick this off somehow.. I've decided to force myself to finish this by entering it in the design contest.
Based on the Pilot Cobra Z kit designed for Norvel .061's and oversize radio gear, and by based on I mean it's a box fuselage with a Hershey bar wing of approximately the same dimensions.. I've been doodling out what I will call the Cobra II I guess (how inspiring!).
Almost ready to start cutting parts, about 60% of the CAD bits re done.
Drawn around a Profi FIRE .049/.061, it will fit any beam mount 1/2A as is. [ATTACH]2095407[/IMG]
Based on the Pilot Cobra Z kit designed for Norvel .061's and oversize radio gear, and by based on I mean it's a box fuselage with a Hershey bar wing of approximately the same dimensions.. I've been doodling out what I will call the Cobra II I guess (how inspiring!).
Almost ready to start cutting parts, about 60% of the CAD bits re done.
Drawn around a Profi FIRE .049/.061, it will fit any beam mount 1/2A as is. [ATTACH]2095407[/IMG]
05-12-2015, 11:24 AM
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Now that I think about it - the airfoil is different, the fuselage is different, the tail group is different.. it needs a new name.
I had this name in reserve but perhaps this is the correct project, since I have drawn in a Profi engine as the base design.. I hereby dub this aircraft the "Profilactic".
I had this name in reserve but perhaps this is the correct project, since I have drawn in a Profi engine as the base design.. I hereby dub this aircraft the "Profilactic".
09-28-2015, 05:58 PM
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With all this free time on my hands as my neck knits up, and since I'm not suffering from 9 hours straight in front of a PC monitor at work every day.. I actually don't mind 2-3 hours CAD work at a spell. So with the deadline looming but free time in abundance for the next 3-4 weeks, I've tucked into the small details and nearly cracked off all the part design in CAD. It does take a while to make all the little final decisions, interlocking tabs, yada yada... esp. if you lean to the obsessive side.
I think I will be ready to cut parts by tomorrow afternoon. Faint jpeg of the chaotic drawing board.
I think I will be ready to cut parts by tomorrow afternoon. Faint jpeg of the chaotic drawing board.
09-28-2015, 06:14 PM
#7
RCU's final stage of enlargement looks about 110% of actual size, so that gives a pretty good idea of what it'll look like. It looks like a very worthwhile speedster design.
I think you could break the build up into a bunch of small bites and pull it off. For me, covering is such a pain when I'm feeling 100%, that it would be the most challenging part of the build going into that phase with a pain in the neck already in motion.
I think you could break the build up into a bunch of small bites and pull it off. For me, covering is such a pain when I'm feeling 100%, that it would be the most challenging part of the build going into that phase with a pain in the neck already in motion.
10-03-2015, 09:10 PM
#10
10-04-2015, 06:23 AM
#12
Looks good. Nice start. Do you cut your own parts?
I need to learn some cad. I got a program a few years back.
The learning curve was to steep for me.
I guess I kind of drifted away and never went back to it.
I need to learn some cad. I got a program a few years back.
The learning curve was to steep for me.
I guess I kind of drifted away and never went back to it.
10-04-2015, 06:37 AM
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PS - yeah it gets a bit stronger every day. Usual routine is I do this and that until it gets tired and sore then my wife orders me to lie down and take it easy. Sitting at a keyboard or building bench I'm good for 15 minutes at a stretch then things start to get grumpy.
AJ - yeah, I have a 12"x20" 60W laser.. scored it from a guy who figured he'd make a home business out of laser cuts paper models. Didn't work out I guess. It's definitely a luxury toy.. had to smooth talk my way around my wife on that one.
AJ - yeah, I have a 12"x20" 60W laser.. scored it from a guy who figured he'd make a home business out of laser cuts paper models. Didn't work out I guess. It's definitely a luxury toy.. had to smooth talk my way around my wife on that one.
10-04-2015, 10:48 AM
#15
Wouldn't the hole for the carbon tube have been best placed in the center of the rib. At the moment inverted flight there will be plenty of balsa as the air pressure loads the monokoted ribs pressing on
the carbon. Imagine the entire wing ripping off the rod on a hard pull up.
the carbon. Imagine the entire wing ripping off the rod on a hard pull up.
10-04-2015, 01:29 PM
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There will be a vertical grain shear web the full span and the D-box is capped - the negative g rating will be lower than the positive but it ought to suffice.
The CF spar is arrow shaft - .175" OD - that I get in bulk cheap from the place I get the Demon spars. So I used it as much for a building jig as a spar.
I'm not aware of any ratified records for 1/2A speed other than CL, it's up to the 1/2A thread subscribers to set some.
The CF spar is arrow shaft - .175" OD - that I get in bulk cheap from the place I get the Demon spars. So I used it as much for a building jig as a spar.
I'm not aware of any ratified records for 1/2A speed other than CL, it's up to the 1/2A thread subscribers to set some.
10-04-2015, 06:20 PM
#21
Yeah, they don't allow drinking either...!
Information about what the current record for AMA Class 301 1/2 A Speed hasn't been as easy to find as let's say finding out the World's Hot Dog Eating Record.
In the past I hung out at Delphi Forums C/L Speed area to keep track of current events..but it's been awhile. Looking at recent AMA Nats results, Charlie Legg, Bill Hughes and Carl Dodge show up consistently at the top. Charlie Legg has been running a scratch built engine that uses some unorthodox features but finding more details has been fruitless. I seem to recall that either his cases or liners or both are made from stainless. The last speed I saw in print from a Nats was 137 mph on 47 foot lines. They can use either two .012" lines or a single .018" solid wire [shooting from memory here]. The models have a max weight of 10 ozs.
I'm pretty sure that 150 mph has been achieved, but I'm not sure if it has ever been officially recognized.
Information about what the current record for AMA Class 301 1/2 A Speed hasn't been as easy to find as let's say finding out the World's Hot Dog Eating Record.
In the past I hung out at Delphi Forums C/L Speed area to keep track of current events..but it's been awhile. Looking at recent AMA Nats results, Charlie Legg, Bill Hughes and Carl Dodge show up consistently at the top. Charlie Legg has been running a scratch built engine that uses some unorthodox features but finding more details has been fruitless. I seem to recall that either his cases or liners or both are made from stainless. The last speed I saw in print from a Nats was 137 mph on 47 foot lines. They can use either two .012" lines or a single .018" solid wire [shooting from memory here]. The models have a max weight of 10 ozs.
I'm pretty sure that 150 mph has been achieved, but I'm not sure if it has ever been officially recognized.
10-04-2015, 07:07 PM
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I believe any given engine has a higher top speed potential on a suitable RC model than it does when dragging lines around. I don't think it will be that hard to achieve 150, but it will require some focused effort.
10-04-2015, 07:10 PM
#24
I think the top competitors who have access to bins full of the best matched parts could do quite well in RC.
Controlling / dumping heat that builds in the lower crankcase is as big of an issue as in the upper end.
If I ever tried it again, I'd be sure to pay more attention to that.
Controlling / dumping heat that builds in the lower crankcase is as big of an issue as in the upper end.
If I ever tried it again, I'd be sure to pay more attention to that.
