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Gravity Rider Kit-bash build thread

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kruland

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Hi all. Although I've lurked here for a year now, I have posted but once. So, to help break the ice, I thought I'd post a spring build thread.

For Christmas I was given a nice selection of kits. One of them was Sunward Gravity Rider. After reading the review on RocketReviews, I learned the rocket was grossly over weight (or under powered). Others have decided to cluster it. I instead thought I'd just try to lighten it up.

The kit comes with 3x 18-inch RT56 tubes, 3 plastic NCs with canopies, 2 short sections of RT50, some laser cut balsa fins, and a 18mm motor mount. Seems like a perfect collection of parts to work with.

I asked the resident rocket designer (my 7 year old) for some ideas. He thought Sunward's original design was really cool (I guess I know who selected this present) and it shouldn't be changed. After showing him the math, he agreed that it had to be lightened but we should still try to keep as much of the original design as possible.

We decided to drop the 3rd tube and nose cone. This might drop the weight by 3 or more ounces. Then we decided to build a "side-by-side futuristic space fighter" which maintains quite a bit of the tail design.

After angle cutting the bottoms of the RT56, they were glued together side-by-side. In order to make for a more sleek look, the boss had me glue some card stock to the tubes to smooth out the transition. The little sections of RT50 will cover the aft end.

Upon advice of the chief designer, the sections of angled RT50s were then glued to the pair. The lengths and orientation was adjusted from Sunward's original just because we wanted to.

The kit comes with 3 pairs of laser cut fins. However, the left over triangles look like they might be useful too. I'm expecting the rocket to end up a pair of wings, pair of elevons, and some more drag strategically placed to increase the coolness. Unfortunately, the boss is playing at a friends house so this decision will have to wait for a while.
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Jaguar xjr-14

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mjennings

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Under powered is right! It is a really cool bird though. I need to rebuild mine as a cluster (maybe 24 mm) she didn't clear the rod on a B and cleared the rod by maybe 15 feet on a C, if memory serves me but it was close to 3 years ago now. Part of the problem was I over built the aft end, the mid body chute compartment doesn't help the CG either.

Cool looking start. Welcome to the forum!
 

Fishhead

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http://www.rocketreviews.com/reviews/all/sw_gravity_rider.shtml

Thought this might make for some interesting reading for you. I took the pics of Chan's Gravity Rider for this review. It was DEFINITELY underpowered.;) I think the original Canaroc design might have been BT-50 based, which would have been fine with single 18mm power, but the upscale needs a cluster or at the very least 24mm power.
 

sunward

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As noted, the kit has been entirely redesigned.

If you need extra parts to make it a cluster, contact me off line.
 

Fishhead

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The new version is a 2X18mm cluster
Very true. I was glad to see it after witnessing Chan's flight.
The Gravity Rider and Galactic Wave were among the rockets I brought with me a few weeks back when Chan and I were informed that VOA is no longer rocket-friendly. I got one flight in that day before we were shut down, but both of these were loaded and ready.:(:confused2:
 

kruland

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Angelo,

Thanks so much for the offer. I love the way the kit providers support their customers. I am a little nervous about clustering in general since I have never done it before. Does it require more juice than provided by Estes' 4-AA launch controller? An intro to clustering should really be another thread.

Kevin
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FERRARI F2005
 
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TheAviator

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Angelo,

Thanks so much for the offer. I love the way the kit providers support their customers. I am a little nervous about clustering in general since I have never done it before. Does it require more juice than provided by Estes' 4-AA launch controller? An intro to clustering should really be another thread.

Kevin
The short answer is YES, VERY YES. Usually when igniting clusters, one wants at least a 12V car battery for juice, as this can provide several hundred amps. If you are launching by yourself, this could be as simple as hooking a launch box to the battery in your car. Another alternative is those big 6V lantern batteries, although I would use two in series, personally.

Add Q2G2 igniters and you should have a worry-free first cluster. You can use the Estes Solar igniters, but why would you when the Q2G2's are available?
 

ScrapDaddy

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Just a friendly reminder do NOT use 2XD21 it WILL SHRED!!! I looked at the warning on apogee's webpage :(
 
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Fishhead

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Just a friendly reminder do NOT use 2XD21 it WILL SHRED!!! I just wish I looked at the warning on apogee's webpage :(
:roll:Speaking from experience on a different bird, I'd have to agree with this.:jaw:
 

sunward

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Question on clustering answered. Thanks TheAviator
Just a friendly reminder do NOT use 2XD21 it WILL SHRED!!! I just wish I looked at the warning on apogee's webpage :(
D21? uh?

The only recommended engines for the new kit are B4-2 (first flight) and C6-3. Never tested on 24mm. Memo to Apogee.
 

TheAviator

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Question on clustering answered. Thanks TheAviator

D21? uh?

The only recommended engines for the new kit are B4-2 (first flight) and C6-3. Never tested on 24mm. Memo to Apogee.
The D10 and D21 are both 18mm composites. I imagine the D21 warning is more of a "hey, I did this, you probably shouldn't."
 

kruland

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I had to leave town on business for a few days and didn't get much time to work on this project. Although the consensus appears to be the stock model must be clustered (one motor in each tube), I built the one 18mm motor mount which came with my (old pre-redesign) version of the kit and stuck it in one of the tubes.

Nothing special about the motor mount. My only deviation from the instructions was to drizzle thin CA on the end of the tube so it will last a while. I'm very optimistic this will be flown many times :)

I inserted it to the minimum depth I could and still have the entire aft centering ring within the tube. Even so, it did seem to hand out quite a bit throwing off the aesthetics.
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BMW GS HISTORY

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kruland

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Some balsa triangles were glued to the leading edge of the larger "wing" fins.

The fins received a nice coat of watered down wood filler. Note to self, when kids help with this, make certain they don't use too much, it either ends up warping the wood or increases sanding time.

The edge between the paper transition and body tube also got a little coat to help break up the edge. Sunward's body tubes are super smooth and spiral free so there was no need to give the whole tube the treatment.

The larger wing fins were mounted on the underside, and the rudders on the top side. All the fins are wedged between body tubes so they will be nice and strong without a lot of extra glue. We added some smallish scrap triangles near the front of the body tube to increase visual interest.

I am a little concerned about the CG being too far aft -- but a swing test will have to wait until our blizzard leaves town.
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ALASKA DISPENSARIES

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ScrapDaddy

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The D10 and D21 are both 18mm composites. I imagine the D21 warning is more of a "hey, I did this, you probably shouldn't."
Well not exactly it's more of a friendly reminder of the coolest looking way of destroying a beautiful rocket.........I didn't do it Tim van milligan found out the hard way :D
 

kruland

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After taking it outdoors for a swing test, I decided it had some chance of flying upwards. I really wanted to try to fly it, but the weather never seemed to cooperate. Instead I just went to paint.

After sanding, filling, priming, and sanding, we decided to go green with it. (What? There's a contest for green rockets you say?)

I bought a can of Krylon Emerald Green and have to report that the new Krylon is horrible. I had problems with it last year and thought - one more try - and again, it cracked, peeled and otherwise frustrated me.

Every time I put my finger to the trigger, I was scared if this coat would require me to back all the way up. Needless to say, that was my last can of Krylon.

In the end, I'm not overly excited about the paint, but I think it will look fine 300 feet in the air!
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LOS ANGELES DISPENSARY

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kruland

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It was the "standard" Krylon "Emerald Green".
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Stratus
 
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les

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Just a friendly reminder do NOT use 2XD21 it WILL SHRED!!! I looked at the warning on apogee's webpage :(
I built mine to use 2x D12. First flight it left one of the main fins behind.
I used epoxy to reattach (and beefed up the other fin).

I can imagine what 2x D21 would do...
 

kruland

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I finally was able to make it out the field. It was a beautiful days and the kinds were very excited to launch and chase.

I was able to shoot off this model as it stands on a single C6-3. The rocket went up about 100 feet, made a sharp left up wind and traveled horizontally for about 100 yards. I was thankful I didn't use a longer delay, because the chute popped about 30 feet off the ground. But, a successful recovery is a successful flight!

It was a moderate and steady wind of about 7-10mph.

So what should be the next steps? Is there anyway to correct the aerodynamics in the current configuration? What would nose weight do?

Angelo sent me another motor mount (Thank you very much!) I will give that a try but since I need new ground support it might not happen right away.

Kevin
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LIST OF PENNY STOCKS
 
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