Has anyone done any mods on a estes big bertha ? I have one and im looking to tune it up.If you have any pics please post them.
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If you stick 3 18mm motors in it, it becomes an Estes Ranger. Cut the body in half it becomes a mini bertha.. Try sanding those humungous fins in a tear-drop airfoil to "tune it up"...Its a big bertha...Not much to change.
Thanks , i used it the other day , i angled it into the wind and it didnt get enough height , so it spacked , and soon as the nose dug in the ejection charge came out and spat the stuffer tube out for about 100m.
I have the stuffer tube out now , is there anything i can do from there ?
Karl
I have the stuffer tube out now , is there anything i can do from there ?
Karl
trogdor
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Actually, the baby bertha has fins about 25% smaller than the regular bertha (not the bt5 mini-bertha)... noticed this when I built one this past weekend and got the berthas together for a family pic! Anyone know if this was also the fin size on the old estes 80s Rascal?
Yeah please ! Have you got a rocksim file aswell ?
marvSRG
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Sorry, no Rocsim file b/c I don't have the program. David Reese (daveyfire) did run it for me, though, and he may still have the file.
It wasn't that hard to do. I first cut out, sanded, and airfoiled the fins. Then I soaked the fins in epoxy. Next I got a 38mm tube (actually a very, very rigid paper towel tube I ran across), and CA'd the fins to that. Then I cut slits in the main body for these to fit into and used Great planes wood glue to put the fin/motor tube assembly into the slotted body. The motor tube fit right in (I'm sure standard 38mm tubes will work), and it extended through most of the body of the rocket, strengthening it highly. The result was a very rigid airframe with the exeption of about 2" at the top where the motor tube didn't reach. This allowed for the nose cone shoulder to slip in and there was some room for the recovery system. Next I applied HEAVY JB Weld (with milled fiberglass mixed in) fillets to the fin roots. The fin slots were a little large, so this allowed the JB to further adhere the fins to the motor tube, as well as adhere them very strongly to the main airframe, and it covered up some of the large fin slots still exposed. I neglected to attach the nylon shock cord previously (was planned to sandwich it between the motor and main body tubes with JB Weld), so I cut two holes in the upper section and ran it through those and tied it (it was the thin, round nylon "twine"). I then attached that to the nosecone, attached a LONG orange surveyors tape streamer, and put in the needed nose weight (the Rocsim file says what it is, I can't remember). I also attached railguides. The rocket was then painted up and ready to fly. Motor rention was a snap because the G69 has it's own thrust ring (as does all Pro-X motors), and the motor tube was such a tight fit that it was a real work load to pull the motor out, even with pliers. I had to peel out the bottom of the tube for the motor to fit. I couldn't get up into the tube enough to peel out the area where the top of the motor would be, so after a good push, the held the motor VERY tightly. At the next club launch, I loaded her up and flew her. WHAM! What a burst of the pad for a beautiful, incredibly fast arcing flight to around 4000-5000ft. David reported that Rocsim said it would get about 4900ft. and just below mach. I think it did about that. It was such a great, necksnapping flight! And believe it or not, but someone actually spotted it coming down, and it landed right in the to the side of the airstrip way back down the field (we fly at a farm with a grass airstrip running through it). Unfortunately the streamer didn't fully open and that resulted in a fast landing and a broken off fin, but other than that, she worked great. Oh yeah, I also packed the rocket full of orange tempra paint powder. This allowed the rocket to be seen at apogee and tracked visulally on the way down. I'll fix it and fly it again soon. I may do a more planned (this was spur of the moment if you didn't notice from the parts list) beefed up Bertha with glass fins, fiberglass, a real 38mm tube, etc, and this will allow for much more powerful motors! But I'm stickin with this one for now...the Pro38 G's are awesome in it! With an adapter I'm sure all other motors work just fine...even down to A's and B's!
Hope it helped, and I'll post a pic later,
It wasn't that hard to do. I first cut out, sanded, and airfoiled the fins. Then I soaked the fins in epoxy. Next I got a 38mm tube (actually a very, very rigid paper towel tube I ran across), and CA'd the fins to that. Then I cut slits in the main body for these to fit into and used Great planes wood glue to put the fin/motor tube assembly into the slotted body. The motor tube fit right in (I'm sure standard 38mm tubes will work), and it extended through most of the body of the rocket, strengthening it highly. The result was a very rigid airframe with the exeption of about 2" at the top where the motor tube didn't reach. This allowed for the nose cone shoulder to slip in and there was some room for the recovery system. Next I applied HEAVY JB Weld (with milled fiberglass mixed in) fillets to the fin roots. The fin slots were a little large, so this allowed the JB to further adhere the fins to the motor tube, as well as adhere them very strongly to the main airframe, and it covered up some of the large fin slots still exposed. I neglected to attach the nylon shock cord previously (was planned to sandwich it between the motor and main body tubes with JB Weld), so I cut two holes in the upper section and ran it through those and tied it (it was the thin, round nylon "twine"). I then attached that to the nosecone, attached a LONG orange surveyors tape streamer, and put in the needed nose weight (the Rocsim file says what it is, I can't remember). I also attached railguides. The rocket was then painted up and ready to fly. Motor rention was a snap because the G69 has it's own thrust ring (as does all Pro-X motors), and the motor tube was such a tight fit that it was a real work load to pull the motor out, even with pliers. I had to peel out the bottom of the tube for the motor to fit. I couldn't get up into the tube enough to peel out the area where the top of the motor would be, so after a good push, the held the motor VERY tightly. At the next club launch, I loaded her up and flew her. WHAM! What a burst of the pad for a beautiful, incredibly fast arcing flight to around 4000-5000ft. David reported that Rocsim said it would get about 4900ft. and just below mach. I think it did about that. It was such a great, necksnapping flight! And believe it or not, but someone actually spotted it coming down, and it landed right in the to the side of the airstrip way back down the field (we fly at a farm with a grass airstrip running through it). Unfortunately the streamer didn't fully open and that resulted in a fast landing and a broken off fin, but other than that, she worked great. Oh yeah, I also packed the rocket full of orange tempra paint powder. This allowed the rocket to be seen at apogee and tracked visulally on the way down. I'll fix it and fly it again soon. I may do a more planned (this was spur of the moment if you didn't notice from the parts list) beefed up Bertha with glass fins, fiberglass, a real 38mm tube, etc, and this will allow for much more powerful motors! But I'm stickin with this one for now...the Pro38 G's are awesome in it! With an adapter I'm sure all other motors work just fine...even down to A's and B's!
Hope it helped, and I'll post a pic later,
sandman
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karl2k3,
Our club had a contest day using nothing but Berthas. A parachute altitude, B streamer altitude, spot landing...you name it...fun day too!!
Oh...almost forgot the best part...hehehe!
Scale Bertha!
Mine is the Gemini Bertha, My Little Brother did the Mercury Redstone Bertha.
https://166.82.74.22/attachment.php?s=&postid=5786
He's currently working on a Baby Bertha Little Joe II and I'm working on a Pegasus...for next year.
sandman
Our club had a contest day using nothing but Berthas. A parachute altitude, B streamer altitude, spot landing...you name it...fun day too!!
Oh...almost forgot the best part...hehehe!
Scale Bertha!
Mine is the Gemini Bertha, My Little Brother did the Mercury Redstone Bertha.
https://166.82.74.22/attachment.php?s=&postid=5786
He's currently working on a Baby Bertha Little Joe II and I'm working on a Pegasus...for next year.
sandman
sandman
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Karl,
Go to my local clubs web site. https://www-personal.umich.edu/~hsaulles/
and check out the club newsletter (T-minus-5 in PDF format) and see what we did at our "Bertha-Bash-o-Ramathon".
Especially check out the scale winner. Our own member "Gus's" Vostok Bertha all done with paper paterns (he hates painting). And my Pegasus Bertha (Gus won!).
There were a few other "odd" entrys including a Bertha glider???
and a two stage bertha.
sandman
Go to my local clubs web site. https://www-personal.umich.edu/~hsaulles/
and check out the club newsletter (T-minus-5 in PDF format) and see what we did at our "Bertha-Bash-o-Ramathon".
Especially check out the scale winner. Our own member "Gus's" Vostok Bertha all done with paper paterns (he hates painting). And my Pegasus Bertha (Gus won!).
There were a few other "odd" entrys including a Bertha glider???
and a two stage bertha.sandman
sandman
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Karl,
I knew it was here somewhere!
https://www.rocketryforum.com/showthread.php?s=&threadid=6710&highlight=vostok
Some better pics of Gus's Vostok.
sandman
I knew it was here somewhere!
https://www.rocketryforum.com/showthread.php?s=&threadid=6710&highlight=vostok
Some better pics of Gus's Vostok.
sandman
hokkyokusei
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That's cool. I saw that on the r.m.r descon. Neat idea.
Gus
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Karl,
Here is how I do the wraps (thanks for the compliments, by the way).
Go to the Totally Tubular website and get the diameter measurement for whatever tube you are using, multiply times Pi to get the circumference.
In whatever graphics program you are using, set up a rectangle with the width being the size of the circumference you came up with. The length can be whatever size you want, but most printers won't let you do much over 10". if you need to go longer than that, you'll have to do multiple wraps. Use the thinnest line possible for the box, it'll help later when you cut the graphic out.
Design anything you want within the bounds of your box. The horizontal center of the box will be the front of your rocket. The left and right edges of the box will be the back side of the rocket.
When you're done designing, make a short vertical line at the upper edge of the box which overlaps onto your graphic just a tiny bit. Then select the line, and the graphics box and use the program's alignment tool to center the line in the middle upper edge of the box. Make a similar line at the bottom of your graphic. After you cut out the graphic, you will use these little "registration" marks to position the graphic on the body tube so the free edges line up right.
Print the graphic onto full sheet label paper (available at most office supply stores). I've used several different types and haven't had a problem with any of them.
Cut out the graphic using a metal straight edge.
On the body tube, use a piece of angle iron to draw a thin straight line down the body tube.
Rip a small strip of the backing paper off your graphic going down the vertical middle from your top registration mark to your bottom one. Postion the graphic's top mark at the top of the body tube line and the bottom mark on the line at the bottom of body tube. When you've got it perfect, rub the paper down. Then peel the rest of the backing paper off, one side at a time, and working from the center out, rub the paper down with the slippery side of the backing paper you peeled off.
I know it seems like it would be easier to just line up one edge of the graphic on the line and work your way around, but it is almost impossible to line up the edges that way. Until I started using the registration marks, it almost never came out right.
When you're done, spray the paper with clear spray paint. I use Rustoleum. If you use a different brand, I suggest testing a piece first to make sure the clear doesn't make the colors run.
Some general hints:
The graphics look better on white tubes. The regular Estes tubes I spray white and let dry a day or two before putting the wrap on.
After I draw the line on the body tube, I erase all but the very top and bottom of the line since it tends to show through any white parts on the graphic after it's clear coated.
If you can incorporate a vertical black line, or background, at the left and right edges of your graphic, it will help hide any slight misallignment of the graphic on the back side of the rocket. Any space that's left between those edges you can easily hide with a thin permanent marker.
Similarly, if you are using more than one wrap, a horizontal black line where the two wraps meet can be made to disappear with a marker.
It is almost impossible to make horizontal, or slanted lines meet up perfectly on the back side of the rocket.
If the graphic overlaps the area where the fins go, leave white in those areas, just a little wider than the fins, so you can add fillets. Apply the wrap whole, then use an xacto knife to cut out the white areas.
Hope that helps. It's kind of a pain the first few times you do it, but once you get it down it lets you do some amazing graphics that you could never do any other way.
Attached is a photo of 6 Estes BLU 97B Cluster bombs I made for a launch at my kids school using this technique. That rocket is perfect for a first attempt at this technique because the body tube is less than 10" long, and the fins are down below the graphic.
Have fun.
Here is how I do the wraps (thanks for the compliments, by the way).
Go to the Totally Tubular website and get the diameter measurement for whatever tube you are using, multiply times Pi to get the circumference.
In whatever graphics program you are using, set up a rectangle with the width being the size of the circumference you came up with. The length can be whatever size you want, but most printers won't let you do much over 10". if you need to go longer than that, you'll have to do multiple wraps. Use the thinnest line possible for the box, it'll help later when you cut the graphic out.
Design anything you want within the bounds of your box. The horizontal center of the box will be the front of your rocket. The left and right edges of the box will be the back side of the rocket.
When you're done designing, make a short vertical line at the upper edge of the box which overlaps onto your graphic just a tiny bit. Then select the line, and the graphics box and use the program's alignment tool to center the line in the middle upper edge of the box. Make a similar line at the bottom of your graphic. After you cut out the graphic, you will use these little "registration" marks to position the graphic on the body tube so the free edges line up right.
Print the graphic onto full sheet label paper (available at most office supply stores). I've used several different types and haven't had a problem with any of them.
Cut out the graphic using a metal straight edge.
On the body tube, use a piece of angle iron to draw a thin straight line down the body tube.
Rip a small strip of the backing paper off your graphic going down the vertical middle from your top registration mark to your bottom one. Postion the graphic's top mark at the top of the body tube line and the bottom mark on the line at the bottom of body tube. When you've got it perfect, rub the paper down. Then peel the rest of the backing paper off, one side at a time, and working from the center out, rub the paper down with the slippery side of the backing paper you peeled off.
I know it seems like it would be easier to just line up one edge of the graphic on the line and work your way around, but it is almost impossible to line up the edges that way. Until I started using the registration marks, it almost never came out right.
When you're done, spray the paper with clear spray paint. I use Rustoleum. If you use a different brand, I suggest testing a piece first to make sure the clear doesn't make the colors run.
Some general hints:
The graphics look better on white tubes. The regular Estes tubes I spray white and let dry a day or two before putting the wrap on.
After I draw the line on the body tube, I erase all but the very top and bottom of the line since it tends to show through any white parts on the graphic after it's clear coated.
If you can incorporate a vertical black line, or background, at the left and right edges of your graphic, it will help hide any slight misallignment of the graphic on the back side of the rocket. Any space that's left between those edges you can easily hide with a thin permanent marker.
Similarly, if you are using more than one wrap, a horizontal black line where the two wraps meet can be made to disappear with a marker.
It is almost impossible to make horizontal, or slanted lines meet up perfectly on the back side of the rocket.
If the graphic overlaps the area where the fins go, leave white in those areas, just a little wider than the fins, so you can add fillets. Apply the wrap whole, then use an xacto knife to cut out the white areas.
Hope that helps. It's kind of a pain the first few times you do it, but once you get it down it lets you do some amazing graphics that you could never do any other way.
Attached is a photo of 6 Estes BLU 97B Cluster bombs I made for a launch at my kids school using this technique. That rocket is perfect for a first attempt at this technique because the body tube is less than 10" long, and the fins are down below the graphic.
Have fun.
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