[Cloning] Estes Javelin question

[Spacepirate R]

Soon I will be cloning the first rockets that I had, the Estes Javelin and Super Flea combo! I have the nose cones (beautiful ones from Semroc!) and I'll be getting the body tubes hopefully this week. My original ones are long gone so it will be great to have them in my fleet again!

I have a question about the nose weight for the Javelin. The plans have a small metal washer and that is what I remember it having. I don't remember it being that heavy, would nearly any small washer do? Should I err on the side of caution and use 2 or 3?

I'll be building the Super Flea just like the plans say but I think I'll build the Javelin with a single body tube instead of two linked ones and I'll attach the shock cord the "teabag" way.

 

[Rich Holmes]

[Completely wrong answer deleted]

 

[Spacepirate R]

https://www.rocketreviews.com/unknown-semroc---javelin.html shows only a screw eye for mass and says it's 5.62 calibers overstable. If that's the design you're going for I'd think you would not need any nose weight. Then again it shows a one piece BT so clearly it's not exactly the same as the plans you're working from.

That is the Centuri/Semroc Javelin, I am making the Estes Javelin that came with the Super Flea.

Like this one: https://www.rocketryforum.com/showthread.php?11534-Estes-Javelin-amp-Flea-build

 

[Rich Holmes]

Sorry, my bad! [Besides the wrong Javelin I quoted stability with no motor installed. D'oh!]

How's this?

https://www.rocketreviews.com/rocksim-estes-javelin-0815b.html

In that file it shows a mass object of 0.3 grams. With an A3-4T it's 1.4 calibers stable. Without the mass it's 1.2 calibers. Bump it up to 1.1 grams and it's 2 calibers.

On the other hand if you're using an A10-T it's 2.4 calibers with no mass object at all. So it depends on whether you ever want to use an A3-4T in it.

 

[Spacepirate R]

Thanks Rich Holmes! An A3-4T would be the most that I would launch it with. I would mostly launch it with a 1/2 or 1/4 A. I remember it going fairly high on an 1/4 A3-3T, and that is a great motor for the Super Flea too. I almost lost the Super Flea on a 1/2 A!

I'll find a 1 gram-ish washer just to make sure.

 

[JPVegh]

It's been around forty years but I don't remember the nose weight. I've since cloned it in MMX scale and she flies great but the basswood nose cone probably helps the cg.

 

[mwtoelle]

I used a #10 flat washer in my Javelin clone. Picked up a bag of 24 washers at Lowe's. Fortunately, I had a vintage NCW-4 from a Javelin/Super Flea for comparison. I did make a minor change and used a single piece of BT-5 instead of the two BT-5P tubes used in the original.

 

[Spacepirate R]

I used a #10 flat washer in my Javelin clone. Picked up a bag 24 washers at Lowe's. Fortunately, I had a vintage NCW-4 from a Javelin/Super Flea for comparison. I did make a minor change and used a single piece of BT-5 instead of the two BT-5P tubes used in the original.

Very good! Thank you!

 

[mwtoelle]

If you fly that Javelin on an A3-4T, have several eagle-eyed people help track it. The extra eyes really come in handy.

 

[MarkII]

I am familiar with the design, because I built an upscaled version of the Estes Javelin that I used for my Level 1 certification.

Owing to its long airframe, the Javelin's design is inherently stable by itself. Nevertheless, in my regular BT-5 version of it I epoxied a small 1/2" diameter washer to the base of the nose cone just to be sure. It and its 435% upscale both fly beautifully, very straight and true, just like the item that it was named after.