Spot On

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boomtube-mk2

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001_zpsj85ma5fa.jpg

Another in my long line of scratch built rockets is “Spot On” which from this photo appear to have a lot of fins going on.

004_zpsvnqhmadd.jpg

Well there’s a good reason that this is an "eight fins and a nose cone" rocket and that’s because it is a two stage rocket.

002_zpsqxera4on.jpg

And not only is it a two stage rocket it is a clustered two stage rocket with two separate booster bits.

005_zpsm1eiybxt.jpg

The reason it can be so short and squat is that apx. 2/3rd of the boosters are located up inside the sustainer’s airframe.

Yes, it is very stable and has flown successfully twice. First time using four “B” motors which left it staging almost before it cleared the launch rod.

A more impressive flight was attained using two C 11-0s and two B 6-4s.
I’m a bit concerned with flying it using two D 12-0s and two C 6-7 as I might not see it again.
 
Last edited:
Since we're on the subject of fins, and I do admire your concept to say the least. Let me introduce you to my first 5 finned rocket. Scratch all the way here. It's still in build mode. I'm a sort of "finmeister", if you will.

100_1041.jpg

Here's the alignment shot.

100_1043.jpg
 
boomtube-mk2 said:
001_zpsj85ma5fa.jpg

Another in my long line of scratch built rockets is “Spot On” which from this photo appear to have a lot of fins going on.

004_zpsvnqhmadd.jpg

Well there’s a good reason that this is an "eight fins and a nose cone" rocket and that’s because it is a two stage rocket.

002_zpsqxera4on.jpg

And not only is it a two stage rocket it is a clustered two stage rocket with two separate booster bits.

005_zpsm1eiybxt.jpg

The reason it can be so short and squat is that apx. 2/3rd of the boosters are located up inside the sustainer’s airframe.

Yes, it is very stable and has flown successfully twice. First time using four “B” motors which left it staging almost before it cleared the launch rod.

A more impressive flight was attained using two C 11-0s and two B 6-4s.
I’m a bit concerned with flying it using two D 12-0s and two C 6-7 as I might not see it again.
Click to expand...
Very slick and clever!
 
Sometimes you just have to go for style over the purity of function.

Your rocket would be perfectly stable and flight worthy if it had only three fins, but then all the coolness would be lost.

Same with the design of the fins, combining straight edges and sharp angles with sweeping curves doesn’t add anything to the aero-aspects of the rocket but once again. COOL!!
 
boomtube-mk2 said:
Sometimes you just have to go for style over the purity of function.

Your rocket would be perfectly stable and flight worthy if it had only three fins, but then all the coolness would be lost.

Same with the design of the fins, combining straight edges and sharp angles with sweeping curves doesn’t add anything to the aero-aspects of the rocket but once again. COOL!!
Click to expand...

With stability always in mind, I can't tear myself away from building something original, and not have an eye on the aesthetics. I have a thing about transitions and exotic fin designs. Your two stage model has unique written all over it, not to mention, it actually looks delicious. Kinda reminds me of these little jewels.

Goetzes-Caramel-Creams.jpg

Bat-mite said:
Kudos to both of you! I wish I were that creative.
Click to expand...

Thanks man. It's all about that drawing board. I'll mix match all kinds of tube sizes, trannys, nose shapes and fin patterns until I get a desired look that appears stable. That's what I love about drawing in Autocad. It's real easy for me to reshape fins for a desired look.
 
Very cool! It looks like you have engine hooks to retain the sustainer stage motors, does it gap stage?
 
I like it! Obviously it works, but I wonder what effect the Krushnik effect has on it? Is it not an issue because of how large the body tube is?
 
SCrocketfan said:
Very cool! It looks like you have engine hooks to retain the sustainer stage motors, does it gap stage?
Click to expand...

Yes, it is gapped staged with 24mm boosters and 18mm sustainer motors.

The booster motors are held in place by wrapping tape around the ends of the body tubes and the portion of the motor sticking beyond the end. This is why I positioned the booster-bits’ fins forward of the tube’s ends.

The segment of the sustainer that is below the rear centering ring is reinforced with a section of coupler and “painted” with a coating of J.B. Weld to help avoid burning the paper tube.

The slots were then cut so a portion of the booster-bits’ fins could protrude through.
My one concern with this was whether or not the staging of the motors would pop the booster-bits off straight enough the booster-bits fins wouldn’t be crunched.
So far this has not occurred.
 
Looking more closely at the pictures this time, it doesn't look like the second stage motors are more than an inch past the slots cut for the boosters. 2 motors, combined with the slots, should provide plenty of air to alleviate the Krushnik effect.
 
If I understand correctly the Krashcart effect is essentially a buildup of pressure waves that occurs when you have streaming gas being expelled out of an enclosed tube?
These pressure waves stall the exhaust and slow it down with a resulting loss of thrust.

Or else it’s magic in which case we’ll get Harry Potter or Willow Rosenberg to deal with it.
 
Whats the deal with the pigment?

When you fly it, do you have "spotters" to track the stages?
Is it hard to "spot" them on the ground?
I was surfing and "spotted" this thread.
Anywhoo..... very cool rocket!
 
Pigments?
Not sure what you are asking about.

So far I’ve only used C 11s in the boosters so they haven’t landed very far from the launch site.
But yes, I do try and have spotters for my two stage flights.
 
I painted the rocket orange and white and saw that it lacked something.

I went to a local shop and had them cut the white spots out of vinyl decal materiel and applied them thinking I might put numerals or something within them.

After they were applied I realized I liked it just the way it stood and thus was born the name “Spot-On”

As for why I chose orange and white? I saw a Quest “Magnum Payloader” rocket painted in that color combo and decided I liked it.
 
boomtube-mk2 said:
I painted the rocket orange and white and saw that it lacked something.

I went to a local shop and had them cut the white spots out of vinyl decal materiel and applied them thinking I might put numerals or something within them.

After they were applied I realized I liked it just the way it stood and thus was born the name “Spot-On”

As for why I chose orange and white? I saw a Quest “Magnum Payloader” rocket painted in that color combo and decided I liked it.
Click to expand...

Gee, and I thought it was a caramel color....duh.....
 
It’s DuplaColor high temperature engine enamel with ceramic. “Chrysler Hemi-Orange” not to be confused with “Chrysler Orange” which is what I used to paint my Cosmodrome “Aerobee Hi”.
 

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