Estes Ranger Fin Pattern Question.

[mojo1986]

Is the fin pattern for the original Estes Astron Ranger the same as the one for the Big Bertha? I'm restoring an old Ranger and have a fin pattern for the Bertha. I have a sneaking hunch that the Ranger was just a 3-engine Bertha with a payload section.

Joe

[tbzep]

Is the fin pattern for the original Estes Astron Ranger the same as the one for the Big Bertha? I'm restoring an old Ranger and have a fin pattern for the Bertha. I have a sneaking hunch that the Ranger was just a 3-engine Bertha with a payload section.

Joe

It's the other way around. The Ranger came first, then Vern stuck a single mount in a solid 18" tube (no payload section) to make the Bertha. :)

I think the fins were the same, at least for the early ones that you had to cut from patterns yourself. I have no idea if they are the same now as they were back then. The Alpha's fins have mutated a little over the decades so the Bertha's could have also. Print the pattern out and compare it to your current Bertha fins.

http://www.spacemodeling.org/JimZ/estes/k-06.pdf

[CPMcGraw]

There is actually a slight difference in the shapes. Not really noticeable at first glance, but it is when you measure them, or place one from the Ranger up against one from the Big Bertha. IIRC, the Ranger fin is just a bit smaller.

I'm inclined to think the difference was more accidental than intentional.

Look at the files from JimZ, especially between the K-6 and the DOM/EIRP plan for the Bertha, then compare them to later Berthas. It's a small difference, but it's there.

[tbzep]

There is actually a slight difference in the shapes. Not really noticeable at first glance, but it is when you measure them, or place one from the Ranger up against one from the Big Bertha. IIRC, the Ranger fin is just a bit smaller.

I'm inclined to think the difference was more accidental than intentional.

Look at the files from JimZ, especially between the K-6 and the DOM/EIRP plan for the Bertha, then compare them to later Berthas. It's a small difference, but it's there.

Is the DOM/EIRP plan larger, or the modern Bertha, or both? If the DOM plan is larger, could it be attributed to error in early mass photocopying/mimeographing and later scanning, or is there a difference in angles?

[ghrocketman]

The Ranger and Big Bertha were intended to have the SAME fins.
As explained directly by Vern, the BB is a single 18mm powered (instead of 3x18 cluster) Ranger minus the payload section.
The Ranger was designed for 3 engine power as the designers did not think available single engines were powerful enough to launch a rocket the size of the Ranger. They obviously were wrong. A Ranger with nothing in the payload gets quite high in a hurry on just a 3xA8-3 cluster as this amounts to a 3/4 C24-3

[Solomoriah]

The Bertha fins may have changed several times along the way; I think we had a discussion of that here before.

[CPMcGraw]

Is the DOM/EIRP plan larger, or the modern Bertha, or both? If the DOM plan is larger, could it be attributed to error in early mass photocopying/mimeographing and later scanning, or is there a difference in angles?

Looking at the fin patterns, there is a difference in the outlines between the EIRP 13 plan and the K-23 plan. This follows the original thought about the BB being a "single-engine Ranger".

The later outline for both the K-23 and 1223 versions are longer along the "tip" edge.

Attached is a composite image of three fin outlines, for the EIRP, K-23, and K-6.

[mojo1986]

I am not really concerned about the evolution of the fin design of the Bertha, or the Ranger , for that matter................all I really need to know is this: was the fin pattern for the original K-6 Ranger identical to that of the original K-23 Bertha? I think GHRocketman is stating that they were identical. Any dissenting views??

Joe

[tbzep]

I am not really concerned about the evolution of the fin design of the Bertha, or the Ranger , for that matter................all I really need to know is this: was the fin pattern for the original K-6 Ranger identical to that of the original K-23 Bertha? I think GHRocketman is stating that they were identical. Any dissenting views??

Joe

If you compare the fins in CP's drawing, you will see that they are very close but not identical, just like he said. They are close enough that the difference could easily be explained by someone making a slight error when drawing patterns in the sets of instructions for the new kits, or someone literally outlining a Ranger fin that had been sanded a little unevenly for the early Bertha plans.

They are close enough that if you sand the edges round on fins from all three patterns and mount them on a rocket, a person would not notice unless asked to compare them. Even then they would expect it was just slight differences in the way the pattern was cut and the edges were sanded.

Of course, you could have just looked at CP's drawing like I did and seen for yourself. ;)
Now you have to decide whether to use the Ranger pattern for authenticity, or just use a Bertha kit cause they are already cut for you. :cool:

[Solomoriah]

The variation is a bit more than that. The Ranger K-6 fin is a bit too short; put all three on one rocket and it wouldn't stand right.

http://rocketry.newcenturycomputers.net/temp/Bertha-Ranger%20Fins.jpg
Yes, I've aligned the upper ends of the fins, but even with the lower end of the root edges aligned, the Ranger fin is still short.

[tbzep]

The variation is a bit more than that. The Ranger K-6 fin is a bit too short; put all three on one rocket and it wouldn't stand right.

Yes, I've aligned the upper ends of the fins, but even with the lower end of the root edges aligned, the Ranger fin is still short.

You're right, there is plenty of difference to us who like to build accurate historical replicas, but I cut and pasted from CP's drawing and they were much closer than that for me. :confused:

The image you posted looks much bigger than real life, at least on my screen. When done at regular size, there's around 1/8" difference aligning the trailing root. That's not very noticeable to the average person, especially to someone who's not a meticulous builder.. You know the type.....those folks who use the same three fins in a kit but it looks like they used three different ones in the build. :chuckle:

[tbzep]

I've taken the Ranger pattern and placed it on top of the two Berthas in CP's attachment. Placing them even at the trailing root where they would be aligned to the rear of the body tube.

Ok, I haven't attached. I'll have to fiddle with the size without losing the dimensions. :mad:

[CPMcGraw]

And now, I'll throw this in just for spite... ;)

When I built my Ranger clone, I just used the Big Bertha fin pattern from (I think) a 1223 version... :D

The spirit of the Big Bertha design was simply, a single-engine Ranger. So, I looked at the Ranger as a Big Brother with an identity complex... :eek:

I didn't find out about the difference in the outline until well after building the clone. So, it stays in the spirit of the originals.

[Solomoriah]

tbzep, I did in fact overlay CP's drawing. I erased the fill and colored the outlines so you could tell them apart, and AFTER I did the overlaying I scaled the image down.

See, your screen is probably between 72 and 96 DPI (maybe higher if you have a nice monitor). The scans CP posted are 300 DPI. He posted his scan as a PDF, which would print at exactly the right size to use the images as templates. I don't care about the exact size nearly so much as I do the relative difference, so I didn't worry about the scaling. So long as the scale of the three fins remains consistent, that's all that matters for my point to be valid.

Having said that... here's another version. This one should be exactly right if printed at 150 DPI, and I've aligned the tail of the root edge rather than the nose. According to GIMP's ruler, the difference is more than 1/8th of an inch between the Ranger fin and either of the Bertha fins.

http://rocketry.newcenturycomputers.net/temp/Bertha-Ranger-2.jpg

[CPMcGraw]

I am not really concerned about the evolution of the fin design of the Bertha, or the Ranger , for that matter................all I really need to know is this: was the fin pattern for the original K-6 Ranger identical to that of the original K-23 Bertha? I think GHRocketman is stating that they were identical. Any dissenting views??

Joe

In a nutshell, no. They were not the same as the K-23, but they were more likely the same as the EIRP #13 (the earliest-known version published). The question I would have is, does anyone have an original (like first-release) set of drawings for the Ranger? Something older than the plans currently posted? That would be the only way to know for sure.

Joe, the shape is similar, but not truly a match. One thing to remember is that the early Big Berthas did not have die-crunched fins, but you had to lay them out and hand-cut them. This means that no two Berthas (or Rangers, for that matter) had exactly the same fins because of the inherent nature of being one-offs every time.

Also, when the EIRP design went into kit production to become the K-23, the fins changed most likely as a result of (1) flight testing, (2) ease of manufacturing, or (3) some other factor we don't know about yet. But change they did. Several times, in fact. The 1223 version appears to be longer than either the EIRP or K versions. That gives us at least three different shapes for the Bertha since it was introduced.

As I mentioned in my other reply, I used the Bertha's fin pattern for my Ranger clone, so it wasn't something I considered vitally important. It was obvious they were intended to be 'relatives' in the same family, and the note that Bertha was a 'simplified, single-engine' Ranger just made the decision that much easier. If you're just looking to have a Ranger in your collection, use the Bertha fin and fly with it. Only go through these deep-rooted 'rivet-counting-gyrations' if you're trying to build a series of clones to show the progression of the design. Then you can point out the differences like a museum curator... :D

[mojo1986]

I seem to recall that the first intro of the Bertha was in an old Model Rocket News, complete with fin pattern. And I recall seeing the Cobra in an old MRN issue too. I'm hoping that the Ranger first appeared in an MRN as well, in which case I could compare fin patterns of the grass root originals. I'll start searching my old copies of MRN tomorrow.

Joe

[CPMcGraw]

EIRP #13 Plan (http://www.spacemodeling.org/JimZ/eirp_13.htm)

JimZ catalog of EIRP/DOM designs from #1 to #84 (http://www.spacemodeling.org/JimZ/eirp.htm)

If there is an earlier plan for the Ranger, it would be nice to have it posted.

[blackshire]

After all of the previous discussion, I'm almost afraid to bring this up, but...does anyone know which version of the Big Bertha fin (if any) Estes down-scaled to create the Mini-Bertha (the BT-20 size "Mini-Brute" kit, not the current Baby Bertha kit)? For anyone who would be interested in building a "Micro-Ranger" (a Mini-Bertha powered by three 6 mm MicroMaxx motors instead of one 13 mm mini motor), its slightly-pointed nose cone is closer in shape to the old BT-60 balsa nose cone used in the Ranger and (older) Big Bertha kits, so a "Micro-Ranger" could be a quite faithful down-scaled version of the Ranger.

[tbzep]

Having said that... here's another version. This one should be exactly right if printed at 150 DPI, and I've aligned the tail of the root edge rather than the nose. According to GIMP's ruler, the difference is more than 1/8th of an inch between the Ranger fin and either of the Bertha fins.

I know about screen size vs reality. I printed his drawings at 300dpi and manually cut and overlayed them to be certain I was scaling down to proper size. That let me physically lay the pattern on a couple of my Berthas to confirm the proper scaling.

You're right, it's more than 1/8" by a whopping .005" (.13"). I used your drawing, changed gimp's ruler to inches, and measured the two most different, red to blue trailing edges, centering my cursor in the lines at the mid point of the trailing edges. BTW, I said about 1/8", not exactly. ;)

Adding in the leading edge differences does make it significantly more, but the average builder will knock enough off sanding the edges round to make that something the average viewer wouldn't notice. BTW, none of us on YORF are average builders or viewers. We've been at this a long time and a tenth of an inch stands out to us. :cool:

I agree there are differences, and have from the beginning of our little interaction on the thread. I just don't think the average Joe will realize the Ranger and Bertha have different fins, much less realize they are different models, assuming they are painted the same and he doesn't look at the motor mount. The average Joe doesn't know about the history of rocketry or the history of the Ranger and Bertha.

[Solomoriah]

True. It's not really important... just an interesting mental exercise.

[tbzep]

True. It's not really important... just an interesting mental exercise.

And mental exercise it was for me. I hadn't used the gimp ruler in a long while and couldn't find the button to switch from pixels. I thought it was at the bottom, but that was the little zoom window. I pulled down menus, right clicked stuff, and finally had the sense to move the toolbar out of the way. There it was, right where I thought it should have been in the first place. :o

[Doug Sams]

I thought it was at the bottom [snip] and finally had the sense to move the toolbar out of the way. There it was, right where I thought it should have been in the first place. :oYesterday, I was escorting my wife to the garage to drop off a car. Along the way, I turned off my radio for something (can't recall why). Later, when I tried to turn it back on, nothing, zip, nada. I tried over and over to get it back on, but everytime I hit the button, the display stayed blank and no sound came out. Finally, after a couple miles and several more attempts, I realized that I'd turned the volume all the way down when I turned if off. And, about that time, the car automatically adjusted its lighting scheme, which sometimes results in the radio display being too dim to see. When I finally pushed the button and cranked the volume, the radio began to play. I then realized what had happened, and was a little red-faced, too :o

Doug

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[Bill]

Along the way, I turned off my radio for something (can't recall why). Later, when I tried to turn it back on, nothing, zip, nada. I tried over and over to get it back on, but everytime I hit the button, the display stayed blank and no sound came out.


Let me guess...while you were doing that, you were saying to yourself, "No joy. Let's recycle. On five, four, three, two, one..."


Bill

[CPMcGraw]

After all of the previous discussion, I'm almost afraid to bring this up, but...does anyone know which version of the Big Bertha fin (if any) Estes down-scaled to create the Mini-Bertha (the BT-20 size "Mini-Brute" kit, not the current Baby Bertha kit)? For anyone who would be interested in building a "Micro-Ranger" (a Mini-Bertha powered by three 6 mm MicroMaxx motors instead of one 13 mm mini motor), its slightly-pointed nose cone is closer in shape to the old BT-60 balsa nose cone used in the Ranger and (older) Big Bertha kits, so a "Micro-Ranger" could be a quite faithful down-scaled version of the Ranger.

When you bring in the "Mini Bertha", you also need to bring in the original Apogee and Apogee II. In the same line as BB being a descendant of the Ranger, the Mini B is a child of the Apogee.

To make matters interesting, the Apogee came first, then the Ranger, and one could suggest that the Ranger was an "upscale" Apogee sustainer.

See the attached "Family Portrait" of fins...

[jdbectec]

When you bring in the "Mini Bertha", you also need to bring in the original Apogee and Apogee II. In the same line as BB being a descendant of the Ranger, the Mini B is a child of the Apogee.

To make matters interesting, the Apogee came first, then the Ranger, and one could suggest that the Ranger was an "upscale" Apogee sustainer.

See the attached "Family Portrait" of fins...


That attachment doesn't seem to be working for me. :(

[CPMcGraw]

That attachment doesn't seem to be working for me. :(

You need a viewer that can open a TIF. Download the latest version of The GIMP and it should open right up.

I had to use the TIF file format to get this image to upload. Even at the lowest JPG setting in Photoshop Elements, the file was larger than YORF could handle (over 500KB).

The image is 11" x 17"...

[Solomoriah]

That's why I keep saying you should use PNG. You don't need to install any special viewers for PNG... web browsers all open it just fine.

[tbzep]

When you bring in the "Mini Bertha", you also need to bring in the original Apogee and Apogee II. In the same line as BB being a descendant of the Ranger, the Mini B is a child of the Apogee.

To make matters interesting, the Apogee came first, then the Ranger, and one could suggest that the Ranger was an "upscale" Apogee sustainer.

See the attached "Family Portrait" of fins...

Cool....between Kody and me, we have the whole family. :cool: He built his Ranger with a removable mount, so I guess it still counts. :p

[tbzep]

That's why I keep saying you should use PNG. You don't need to install any special viewers for PNG... web browsers all open it just fine.

And a lot of older viewers that don't support PNG can still view it if you change the extension letters to JPG. :cool:

[Solomoriah]

Well, I can see how that might accidentally work, if the underlying display library is more up-to-date than the application itself, but I'd never expect that to happen.

PNG has been supported by IE since 4 or 5, I forget which; Firefox has always supported it, as has Netscape since version 6 or so. Hard to imagine anyone using anything much older and managing to visit this forum.

[tbzep]

Well, I can see how that might accidentally work, if the underlying display library is more up-to-date than the application itself, but I'd never expect that to happen.

PNG has been supported by IE since 4 or 5, I forget which; Firefox has always supported it, as has Netscape since version 6 or so. Hard to imagine anyone using anything much older and managing to visit this forum.

You're right on browsers as far as I know. I've never had any issues with any browsers showing them.

However, I was talking about regular image viewers, such as when you've seen the pic online and saved it to be viewed later. Also, some forums don't accept PNG attachments, but will accept them when they've been renamed to JPG. I've done that in recent weeks. :cool:

[Doug Sams]

http://rocketry.newcenturycomputers.net/temp/Bertha-Ranger%20Fins.jpg Ya know, that's about what it looks like after I've rough cut the fins (before sanding them to match). I'm sure, when I was a kid and had to cut the fins from patterns, that I built rockets whose fins didn't match any better than that. As for the differences in dimensions, as they say in signal analysis, it's down in the noise :D :D :D

Doug

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[blackshire]

When you bring in the "Mini Bertha", you also need to bring in the original Apogee and Apogee II. In the same line as BB being a descendant of the Ranger, the Mini B is a child of the Apogee.

To make matters interesting, the Apogee came first, then the Ranger, and one could suggest that the Ranger was an "upscale" Apogee sustainer.

See the attached "Family Portrait" of fins...Thank you (and Solomoriah) for posting those. I'm not sure, though, if the Apogee II fin planform (was there an Apogee? I thought the "II" in "Apogee II" just denoted its two stages, not a variant number) is part of the Ranger/Big Bertha 'family'--it looks derived rather than scaled because its proportions are different from those of the Ranger and Big Bertha fins.

[Doug Sams]

(was there an Apogee? I thought the "II" in "Apogee II" just denoted its two stages, not a variant number) Yes, the original was shorter. The sustainer was about 1.5" shorter, and the booster was about ¾" shorter. Here's a doc I did comparing the two (http://www.doug79.com/apothree/Apogee1vs2-v4.pdf). The original is shown in one of the early Estes catalogs on ninfinger (http://www.ninfinger.org/rockets/catalogs/estes63/63est8.html). I used that pic to deduce the differences since there aren't any plans around for the 1.

Doug

.

[blackshire]

Yes, the original was shorter. The sustainer was about 1.5" shorter, and the booster was about ¾" shorter. Here's a doc I did comparing the two (http://www.doug79.com/apothree/Apogee1vs2-v4.pdf). The original is shown in one of the early Estes catalogs on ninfinger (http://www.ninfinger.org/rockets/catalogs/estes63/63est8.html). I used that pic to deduce the differences since there aren't any plans around for the 1.

Doug

.Thank you for posting these links, Doug. The only reasons for the change that I can think of are [1] the model proved unstable, perhaps with the heavier "C" motors (although the statement in the above-linked 1963 Estes catalog citation, "May be flown either with or without payload section." militates against this), or [2] the longer tubes in the Apogee II were also used in other kits, allowing Estes to reduce the number of different tube lengths that they had to stock.

[Doug Sams]

Thank you for posting these links, Doug. The only reasons for the change that I can think of are [1] the model proved unstable, perhaps with the heavier "C" motors (although the statement in the above-linked 1963 Estes catalog citation, "May be flown either with or without payload section." militates against this), or [2] the longer tubes in the Apogee II were also used in other kits, allowing Estes to reduce the number of different tube lengths that they had to stock.With those long sustainer fins, it's hard for it to not be stable. But, when you subtract out the payload section and motor area, there's not much room for the recovery system. So that extra 1.5" probably addresses complaints of too little room for shock cord, wadding and streamer.

On the early booster, I suspect they had lots of fried boosters. My experience is that the booster sections that don't enclose the motor, or positively retain it, will often stay attached to the sustainer motor after staging with the sustainer exhausting thru the booster section, with the booster motor having slipped out the back.

By extending the booster section to enclose the motor, they included an aft ring to contain the booster motor such that, upon staging, when the booster motor separated, it would take the booster stage with it.

So, I vote for more recovery bay and positive stage separation :)

Doug

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[jdbectec]

Well, I can see how that might accidentally work, if the underlying display library is more up-to-date than the application itself, but I'd never expect that to happen.

PNG has been supported by IE since 4 or 5, I forget which; Firefox has always supported it, as has Netscape since version 6 or so. Hard to imagine anyone using anything much older and managing to visit this forum.


I'm actually running Vista with IE8, now I'm wondering whats wrong. I'm very thorough about updating all my software.

:confused: :confused: