Well the R-7 is built. At this point I have to add the shock cord, lunch lugs, nose weight for stability.
Not a bad build. If I do it again there are some things I would do different for strength, but for now I just want to see it fly. At this point the models weighs in at 5.0 oz. I don't know if that's good or bad.
The scale fins look small, but I'm going to try to use them, and hope it is stable.

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In a previous message, you said you scaled it to BT-60. Are those BT-60 sections the lowest part of the strapons or somewhere else on the bird?

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The BT-60, is the core of the rocket. The four boosters are glued to the BT-60.

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Got it. Thanks!

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A dark night in a city that knows how to keep its secrets. But high above the quiet streets on the 12th floor of the Acme Building, one man is still trying to find the answers to life's persistent questions. Guy Noir, Private Eye.

Fox Valley Rocketeers: http://www.foxvalleyrocketeers.org

I'd love to see how you set up your parachute etc. On my paper builds, I run the motor tube full length to the nosecone. Then, I use a spent motor casing attached inside the nosecone that slips into the tube, so it acts a bit like a piston for ejection, and helps keep the nose cone on. It then keeps all the ejection gases inside the tube, and the spent case also adds some nose weight, and is a convenient place to hold more if needed. The void between the nosecone skin and the inner tube is where the 'chute/streamer goes. This picture of my Currell V-2 should give an idea of what I mean.

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Great idea! Thanks!

__________________
A dark night in a city that knows how to keep its secrets. But high above the quiet streets on the 12th floor of the Acme Building, one man is still trying to find the answers to life's persistent questions. Guy Noir, Private Eye.

Fox Valley Rocketeers: http://www.foxvalleyrocketeers.org

After going to all of that effort, why not roll some nozzles for the verniers?


Bill

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: countdown begin cr dup . 1- ?dup 0= until cr ." Launch!" cr ;

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This is a test build to see if I could build it and get a stable flight. I have learned in the pass that small pieces like the nozzles for the verniers have a tendency to fall off on take off or landings. If I get this one to fly well I will add them to my next build.

A lot of rain and strong winds this week. I might get a test flight in some time next week.

The weather is better here. The rain has slowed down and the winds are blowing at a calmer speed.
I was able to get what I needed done on the R-7 to get a test flight out of it. Here are some numbers for you:
I had to add 6.0 oz to the nose cone. The rocket weighed-in at 11.0 oz without the motor.
With the the motor installed, it weighed 12.6 oz. With the motor, parachute, and recovery wadding installed, the lift-off weight was 13.8 oz.
I built it to fly on a D12-3 engine.
I used a 3 foot launch rod.
The wind was 3 MPH on lift off.
I built it as light as I could, so I don't have any idea how to lighten it any more.
The flight was pretty good. Everything worked as it should. The stock fins were OK. The height was good for a heavy rocket. The parachute came out, and on landing nothing got smashed or broke off. So I am pleased with the build.
I'm already thinking about building another one. I want the next one to have the frost white color.
Give me your thoughts on this. The D12-3 has a max lift wt of 14.0 oz. The E9-4 has a max lift wt of 15.0 oz. So, would it be better to use the E9 or stay with the D12?
You can see a video of the launch on YouTube at http://youtu.be/a4t_DhNJ1ro

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The E9 actually has a lower safe max lift off weight than the D12; The Estes number is really quite misleading in this case. If you look at the thrust curves, the D12 has a higher maximum thrust, and a higher average thrust:

http://www.rocketreviews.com/compar...o-estes-e9.html

The E9 simply has a longer burn time. Even the Estes E12 isn't any better at lift-off weight, since it weighs more than the D12. You'll really need to move to Aerotech RMS 24/40 motors, or one of their single use 24mm motors, such as the E15 or E20, if you want more speed off the rod.

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Paul
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NAR #87246 www.wooshrocketry.org