Well the monthy club launch was called off so I needed something to do on a windy Saturday besides the usual weekend chores. I didn't want to do another Estes downscale and I didn't want to start anything that would take too long. I am a big fan of the Pemtech designs and I thought that a shrunken 3FNC might fit the bill for a quick project and a fun build.
I didn't have any dimensions to go by so this is really a 3FNC inspired build rather than a true downscale. Call it a homage.
I started with a quick cad drawing to come up the dimensions that I would use for the build.
After looking at the dimensions on the cadd drawing I realized that this build might present a challenge or two. For one thing the airframe length only came to .825 inches and I needed to fit a motor mount, the nose cone shoulder and shock cord. There was not going to be any room for a recovery device so this would be a nose blow recovery design.
I found a little more room by extending the length of the motor shroud slightly. I also decide on a 3/16 shoulder for the nose cone. Even with these considerations I would only have about a 1/4 inch of clearance between the top of the motor tube and the bottom of the shoulder.
With the dimensions finalized I went back to cadd to lay out the shoud pattern, some centering rings and the fin patterns. I printed the shrouds and centering rings on heavy card stock.
Next I cut out the shroud, formed it and glued it. I also cut out my centering rings. I then got out my tube cutter and cut a piece of BT-5 for the airframe, a one inch length of T2+ for the motor tube and a 1/8 inch length of T2 for a motor block.
On to the fins. The fin patterns were printed on plain paper and cut out. I then selected a piece of 1/32 basswood from my pile and used some 3M GP45 spray adhesive to glue on the patterns following the grain. The fins were cut using a sharp #11 blade and the patterns were peeled from the wood.
I was getting close to having all of the parts together for the build I just needed a nose cone. I went back to the wood pile to find a piece of 3/4 X3/4 balsa. Dang it! I was out! So I settled on the next bigger size I had on hand, 1X1. I took my balsa block back to the workshop and cut off a 2 1/2 inch piece and marked the centers to prepare it for the lathe.
The block was placed in the lathe, rounded off, rough shaped and final shaped to nice gentle ogive form. While still on the lathe I sanded it smooth with 400 and then 600 grit. The final exposed length came out at 2.25 inches which is just a tad more than 4 to 1 or just a tad short of a scaled PML 3 inch cone which was my model. I looked at it and decided it was close enough.
I needed just one more part, a launch lug. I took a 1.5mm drill bit and put three wraps of plain paper around the shaft. I backed it off two wraps applied a tiny amount of Elmers and rewrapped it. I carefully removed the drill bit and set the lug aside to dry.
I now had all of the components needed to complete the build.
Whazoooo
Makes my eyes hurt just thinking about working with such tiny parts.
Very well done, can't wait to see the finished product.
Your homage makes us proud.
As an aside, one could use a plastic NC like those in the Gnome kits. There still wouldn't be a lot of room.
Thanks, I looked though my magic drawer of goodies for that very nose cone. I found the Gnome fin can but not the nose cone. It's ok, any excuse to turn a piece balsa...
OK where was I? Oh yeah, I was just about to start assembly. Now that I had my parts together I started by dry fitting the motor mount and tail cone parts. I found my C rings to be a little too snug all the way around so I made few minor adjustments until everything fit just right. I glued a C ring into the top of the tail cone. I notched the inside of another C ring for the kevlar thread to pass through. Then I glued another Cring to the motor tube tied the kevlar to the tube and slid the last C ring into place and applied glue to all of the joints and the kevlars knot. The MMT was then glued into the tail cone. The motor block was glued in as an after thought.
It was about this time when my doggies alerted me to the FEDEX truck pulling into the driveway. It was pretty close to noon so I took a break for lunch.
Allrightythen! After lunch it was time to mark the airframe. I dug out a recently used marking/allignment guide. After sanding the glassine off of the BT-5 it was placed on the guide and tick marks were pencilled in. The marks were extended to lines using a specialized straight edge tool. The tube was returned to the guide and fins were glued in place using CA gel.
In the home stretch! I applied thin fillets of CA gel to the fins. The MMT tail cone assembly was glued into the air frame with white school glue.
The lathe leaves a square hole in the bottom of the nose cone this is how I attach the kevlar on all of my MMX rockets. An appropriately sized balsa plug is fitted to the square hole. Several knots are tied in the kevlar thread. The kotted end is placed in the square hole with a few drops of CA gel then the balsa plug is forced in locking the thread into the nose cone. This is a very strong attachment that has never failed.
The launch lug was trimmed to size and glued on with some CA and thin fillets applied.
The entire rocket was sanded with 400 and then 600 grit and the first coat of primer was applied.
In the home stretch! I applied thin fillets of CA gel to the fins. The MMT tail cone assembly was glued into the air frame with white school glue.
The lathe leaves a square hole in the bottom of the nose cone this is how I attach the kevlar on all of my MMX rockets. An appropriately sized balsa plug is fitted to the square hole. Several knots are tied in the kevlar thread. The kotted end is placed in the square hole with a few drops of CA gel then the balsa plug is forced in locking the thread into the nose cone. This is a very strong attachment that has never failed.
The launch lug was trimmed to size and glued on with some CA and thin fillets applied.
The entire rocket was sanded with 400 and then 600 grit and the first coat of primer was applied.
Might be a bit late on this but I think I'd hollow out the balsa NC just to reduce a bit a mass and give a place as far forward as possible for a little Nose weight clay (Or #9 lead shot) if needed.
I've found over time this almost always benifits the models flying altitudes.
Like you I add a add a loop of kevlar thread Caed to the bottom of the hollowed out cone long enough to attach the shockline from the body. If needed a little clay Noseweight can be packed in around the loop.
Might be a bit late on this but I think I'd hollow out the balsa NC just to reduce a bit a mass and give a place as far forward as possible for a little Nose weight clay (Or #9 lead shot) if needed.
I've found over time this almost always benifits the models flying altitudes.
Like you I add a add a loop of kevlar thread Caed to the bottom of the hollowed out cone long enough to attach the shockline from the body. If needed a little clay Noseweight can be packed in around the loop.
Look'in good can't wait to see it painted.
I found extra nose weight to be absolutely necassary when I built my BT-5 V-2. It just woud not fly stable without it. The addition of 2 .177 cal pellets straightened it right out and now it flys very well.
I'm thinking this one has enough fin that stability won't be an issue and optimum altitude with this particular design wasn't really a consideration. However if I find that stability is a problem I can certainly make those mods easily enough with a 4.5mm drill bit.
Everything I build that is T3 or smaller gets a basswood nose cone to optimize performance and strength. Not to mention that basswood turns a very nice looking finished product.
Well I got a little impatient waiting to finish this one so I rushed it along a little. It didn't come out too bad but I did have a few decal issues. I forgot what a PITA little decals on little rockets can be.
Well I got a little impatient waiting to finish this one so I rushed it along a little. It didn't come out too bad but I did have a few decal issues. I forgot what a PITA little decals on little rockets can be.
Anyway here it is.
I'd like to copy this to the gallery if I may.
__________________
John A. Lee O.S.L.
Alamo Rocketeers NAR Section 661
NAR 87285, L1 8 March 2008
TRA 03040, L1 8 March 2008
Photos of the "Fleet": http://www.flickr.com/photos/23694991@N03/
I used to tell Mom, "...I want to fly rockets when I grow up!"
Well the winds dropped off enough this afternoon to fly a few MMX rockets so it was time for the Micro 3FNC to make its maiden voyage. I set up my pad atop of my chiminea as per usual with the rod more or less vertical. The little gold rocket was placed on the rod and I snapped a quick picture. I waited for my wind socks to go limp and then I pressed the button. The little rocket screamed off the pad and rapidly climbed too maybe 150-175 feet. I thought with all of the filler I had used on the nose cone and fins that this would be a bit of a brick but I was surprised by the speed and altitude achieved. The nose cone popped and she tumbled down, landing about 100 feet from the pad. A quick inspection of the recovered rocket revealed some white residue from the ejection charge but otherwise she was no worse for the wear and ready for a second go.
Well the first launch happened so quickly that I couldn't get that smoke and flame money shot with my crummy little camera. So I decided to give it a second try. The rocket was quickly prepped for an encore performance and once again I waited for my wind socks to indicate a lull in the breeze. I pressed the launch button but this time the rocket ripped off the pad so fast I lost track immediately. I scanned the sky but could not see a thing. I heard the tell tail pop of ejection and from the sound it seemed that the rocket was further away than on the first flight. I strained to hear the sound of the rocket hitting the ground but I didn't hear a thing.
I spent about a half hour wandering around my two acres looking for my 3FNC, paying extra attention to the area where it landed on the first flight. No dice! I couldn't find it, this rocket is officially lost. To add insult to injury I still did not get a liftoff shot.
I launched a few other rockets and got them all back but thats a story for another thread.
Well the winds dropped off enough this afternoon to fly a few MMX rockets so it was time for the Micro 3FNC to make its maiden voyage. I set up my pad atop of my chiminea as per usual with the rod more or less vertical. The little gold rocket was placed on the rod and I snapped a quick picture. I waited for my wind socks to go limp and then I pressed the button. The little rocket screamed off the pad and rapidly climbed too maybe 150-175 feet. I thought with all of the filler I had used on the nose cone and fins that this would be a bit of a brick but I was surprised by the speed and altitude achieved. The nose cone popped and she tumbled down, landing about 100 feet from the pad. A quick inspection of the recovered rocket revealed some white residue from the ejection charge but otherwise she was no worse for the wear and ready for a second go.
Well the first launch happened so quickly that I couldn't get that smoke and flame money shot with my crummy little camera. So I decided to give it a second try. The rocket was quickly prepped for an encore performance and once again I waited for my wind socks to indicate a lull in the breeze. I pressed the launch button but this time the rocket ripped off the pad so fast I lost track immediately. I scanned the sky but could not see a thing. I heard the tell tail pop of ejection and from the sound it seemed that the rocket was further away than on the first flight. I strained to hear the sound of the rocket hitting the ground but I didn't hear a thing.
I spent about a half hour wandering around my two acres looking for my 3FNC, paying extra attention to the area where it landed on the first flight. No dice! I couldn't find it, this rocket is officially lost. To add insult to injury I still did not get a liftoff shot.
I launched a few other rockets and got them all back but thats a story for another thread.
You're in BIG trouble, Bub. I wanted to see this one. You should have brought it to a club launch.
__________________
John A. Lee O.S.L.
Alamo Rocketeers NAR Section 661
NAR 87285, L1 8 March 2008
TRA 03040, L1 8 March 2008
Photos of the "Fleet": http://www.flickr.com/photos/23694991@N03/
I used to tell Mom, "...I want to fly rockets when I grow up!"
Hope you run across the model while your out doing something else very soon. This is one of the main reasons I add those little teflon Plumbers tape streamers to most of my micros. Sure helps Locate Quick off the pad models after ejection as they are on the way down.
Here's crossing everything I have two of that you find 3FNC real soon.
Hope you run across the model while your out doing something else very soon. This is one of the main reasons I add those little teflon Plumbers tape streamers to most of my micros. Sure helps Locate Quick off the pad models after ejection as they are on the way down.
Here's crossing everything I have two of that you find 3FNC real soon.
I tend to find stuff in my yard while I'm mowing. Let's just hope I see it in front of the tractor and not behind it!
Yes streamers surely make them more visible not only on the ground but in the air as well. I flew several SD test rockets yesterday and I found every one of them, even the ones that landed in the pasture behind my property. Unfortunately there was barely room for the kevlar thread in the 3FNC. Gold was probably not the best color choice as I discovered but it sure looked sharp as a static display.
I have already started building a new one. It was just too cool to not have it in my MMX fleet and it really did fly very well. Besides I'm a little bit afraild of what JAL might do to me if I show up at the next club launch without it!
I have already started building a new one. It was just too cool to not have it in my MMX fleet and it really did fly very well. Besides I'm a little bit afraild of what JAL might do to me if I show up at the next club launch without it!
As well you should be!
__________________
John A. Lee O.S.L.
Alamo Rocketeers NAR Section 661
NAR 87285, L1 8 March 2008
TRA 03040, L1 8 March 2008
Photos of the "Fleet": http://www.flickr.com/photos/23694991@N03/
I used to tell Mom, "...I want to fly rockets when I grow up!"
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Originally Posted by Micromeister
To add insult to injury I still did not get a liftoff shot.
