SEMROC Scout breakage

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Scud-B

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A few years ago I bought and built a Semroc Golden Scout kit just so I could play around with some early model rocket tech. Back in the day, when Estes was mass producing these little rockets, was there a way to fly and land them without breaking fins every landing? Every time this thing comes down it breaks the first fin that contacts the ground, even in grass, and it's never at the root where it's glued to the body tube, it's through the cross section of the fin somewhere along its length and all three fins have broken several times at this point.

On an additional note, all three fins get charred by the motor flame during flight. It's odd that the fins never break where they are charred, but they're severely burned at this point. It's just so odd to me that these issues are reoccurring, I'm left to wonder if these were common problems back in the day when the Astron Scout was a popular kit.
 

BEC

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What you're seeing is normal Scout behavior. It is difficult to fly it without having a fin break - it's the nature of the way it comes down. Flying over soft grass is really the only mitigation (or using much harder balsa for the fins than Semroc typically did, and doing the gauze fin-to-body tube reinforcements of the original).

I never had one "back in the day" but did fly the Sprite, which uses the same recovery system, and it, too, would crack fins, even with the extra support of the tail ring and even though it used lighter Series III (short 18mm) motors.
 

BABAR

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Tumble recovery is not for the faint hearted. Even Horizontal Spin, which is sort of both the opposite of but conceptually the perfect tumble recovery (it’s not random but it is orienting the rocket perpendicular to long axis, so you get optimal drag) comes in pretty hot.

also, tumbling rocket is more likely to land on the fin at a weird angle (think jumping off a tall box and landing on your ankle off kilter), which doesn’t help much either.
 
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dpower

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Huh, I’ve flown my 3 Scouts many times, never has a fin break. Perhaps yours has particularly soft balsa? The thickness should make them quite tough. Is it tumbling as expected?
 

BABAR

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Huh, I’ve flown my 3 Scouts many times, never has a fin break. Perhaps yours has particularly soft balsa? The thickness should make them quite tough. Is it tumbling as expected?
Possibilities also include launch weight (how heavy did somebody go with glue and paint), impact surface (grass vs pavement or playa) and luck.
 

nosecone

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At least you found it ! I spent an hour+ trying to find my golden scout years ago 😅
 

Scud-B

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Huh, I’ve flown my 3 Scouts many times, never has a fin break. Perhaps yours has particularly soft balsa? The thickness should make them quite tough. Is it tumbling as expected?
Yeah, it tumbles nicely, just always lands one fin down and breaks it... even in lawn-length grass. Plus the find are ablating away...

I think I understand the concept enough to try to sort out a more draggy Baby Bertha-based shifting CG tumble recovery rocket. I like the idea and the principle involved, but maybe the ball supplied by SEMROC was just too soft.
 

mach7

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I've launched my Scout a few times with no issues. Built stock and painted gold. Nothing fancy, It has yet to have fin issues. The fins and ejection hole do get some charing. My Sprite has never had an issue either. I launch both only on grass.

Sorry your having issues, it's a nice park flyer as it tends to land close to the launcher.
 

Scud-B

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I've launched my Scout a few times with no issues. Built stock and painted gold. Nothing fancy, It has yet to have fin issues. The fins and ejection hole do get some charing. My Sprite has never had an issue either. I launch both only on grass.

Sorry your having issues, it's a nice park flyer as it tends to land close to the launcher.
Yeah, I'm not worried about it. I will say, I've never lost it. My Scout recovers within an easy walk from the launch site, as you said. I've been on and off again with rockets since I was a kid in the 80's, a few broken fins on a rocket I bought just to mess around with isn't that big of a deal. As I said, I think I'm going to try to come up with something more complicated and see what the practical limits of "tumble" recovery are.
 

mach7

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Well, what do you know. I did have a fin break!

I completely forgot about it. I have another that I built but never flew.

Maybe papering the fins would help?
 

Scud-B

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Well, what do you know. I did have a fin break!

I completely forgot about it. I have another that I built but never flew.

Maybe papering the fins would help?
My fins broke in more or less the same location, must be a weak cross-section. Maybe papering would help, I'm unsure if making them more rigid or more flexible is the solution. I had put some thought into a hardwood dowel leading edge, or maybe enabling them to have some spring function to absorb shock... greater airframe drag would help too.
 

BABAR

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Well, what do you know. I did have a fin break!

I completely forgot about it. I have another that I built but never flew.

Maybe papering the fins would help?
Unorthodox but effective

This comes down spinning like top.
Previous flight broke off a fin at the base.

This landed on asphalt with no damage
20210412_081818.jpg
20210412_082145.jpg




 

Scud-B

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Unorthodox but effective

This comes down spinning like top.
Previous flight broke off a fin at the base.

This landed on asphalt with no damage View attachment 459932View attachment 459933



That's actually a really neat idea. I had an Estes Skywinder as a kid, different implementation, but similar in concept.
 

Back_at_it

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Well, what do you know. I did have a fin break!

I completely forgot about it. I have another that I built but never flew.

Maybe papering the fins would help?
I had the Estes Scout many years back and it came with Gauze that you wrapped the top of the fins with where they attached to the body. Added extra and covered the entire fin. Looked like total crap as you would imagine from a 10 yr old kid but it flew well and never broke.

If I did it again today, I think I'd try papered basswood or even plywood.

Scout.jpg
 

Blast it Tom!

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I was going to say, but @BEC and @Back_at_it have posted the best - I built this one as a kid in the late 60's and distinctly remember the stiff gauze buried in white Elmer's glue. I didn't like it because it was so "draggy" - and like I said, kids aren't too smart, if you can only fly to 1000' or so without severe risk of rocket loss, why do you care?! But I don't recall ever breaking a fin...
 

Scud-B

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I suspect Semroc's motivation was that everyone would do one or two launches of their Golden Scouts, related to the anniversary, and then put it up on display somewhere. It seems very possible that my repeated flights are greatly in excess of the designed life span.
 

Blast it Tom!

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I suspect Semroc's motivation was that everyone would do one or two launches of their Golden Scouts, related to the anniversary, and then put it up on display somewhere. It seems very possible that my repeated flights are greatly in excess of the designed life span.
Could be. A golde scout wouldn't look as pretty with that gauze mesh. I recall it being pretty heavy, you saw it quite clearly.
 

BABAR

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With the proliferation of home 3D printers, this would be a nice model for a plastic fin can that slides over the body tube, maybe with a transition bevel at the front end. Not experienced in doing this, are any of the plastics slightly flexible, so they’d “bounce” rather than break?
 

Scud-B

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PETG and PLA + would both work just fine in this application. I'm working on iterating a 1/37 scale Thor IRBM that is entirely 3D printed.
 
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