Spikey 3.0 Build Thread

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Random Flying Object

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After building "Spikey" (my 5") L3 project I found that flying that beast on a regular basis isn't very feasible. I scaled down the design to a 54mm motor mount and have started building a 3" version of my original design. This rocket will be far less complex and much easier to prep and fly. The airframe is built with thin wall fiberglass tube from Rocketry Warehouse. Other than the interesting fin layout this should be a fairly straight forward build. The electronics will consist of: TeleMega, Easymini, a power control board, HackHD video cam, 5.8GHz video TX, and a few LiPo packs.


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Attached is a picture of the 54mm motor tube getting all the centering rings and aft fins glassed on. After all of the internal fillets on the motor tube are complete the body tube gets slid in to place and the forward fins get installed.

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As someone awed by the avionics in your previous build, I am greatly looking forward to seeing what you do here. Maybe I can steal some ideas for when I start on my 3 inch Dark Star build!
 
The AV bay on this one won't be near as complex as Spikey 5.0. The flight computer I used on Spkiey 5.0 is currently on a 4" PCB of which will not fit in the 3" airframe for this rocket.

I am using the following:

Primary altimeter/telemetry - TeleMega
Secondary Altimeter - EasyMini
Camera - HackHD
Video Transmitter - 5.8GHz
A prototype power control board
LiPo packs for the above

That is about all I could squeeze into that AV bay. I might have enough room to add a prototype GPS OSD, but I am not done with the board yet.

I am working on a revised version of my larger flight computer that will fit within a 3" airframe but it won't be ready until later this year, maybe ready for Airfest or Balls.


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The rear fins are mounted and body sections fitted together. Next is the av bay buildup and the body tube threaded inserts.

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Finally got around to working on the AV bay. Everything is mounted now I just need to do wiring and shielding.

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Subscribed...how did I miss this build thread. I followed your L3 Spikey thread which I found both interesting and inspirational. Please post some pics of the shielding method you use with an explanation.
 
I'm curious... What type of antenna is attached to the telemega?

Great av-bay by the way!
 
I'm curious... What type of antenna is attached to the telemega?

Great av-bay by the way!

MFJ-1719S

I have used a similar antenna on a ground based video project. I will let you know how it performs in this case.

ImageUploadedByRocketry Forum1429321367.955449.jpg


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MFJ-1719S

I have used a similar antenna on a ground based video project. I will let you know how it performs in this case.

View attachment 261219


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I noticed you are using metal standoffs instead of nylon. I have always used nylon because I felt the need to remove as much metal out of my AV bays in order to mitigate interference. Keeping in mind this assumption is based on very little third party knowledge on the topic so I would be interested in your thoughts?
 
I noticed you are using metal standoffs instead of nylon. I have always used nylon because I felt the need to remove as much metal out of my AV bays in order to mitigate interference. Keeping in mind this assumption is based on very little third party knowledge on the topic so I would be interested in your thoughts?

It is true that any conductor placed in an RF field will impact that field. However, in this case that impact is extremely small. I use metal standoffs and metal threaded inserts because I don't want the PCB's coming loose during high acceleration and/or vibration. I use all LiPo's, so a loose board causing a short basically means my AV bay is going to catch fire. Better that the recovery systems operated properly rather than worry about RF signal strength.


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Well, the flight in Argonia started well, but it didn't make it past the Argonia force field. I ended up with a great display of roll coupled resonance. After a few spinning loop to loops it deployed the chute and broke a rear fin upon touchdown. Atleast I didn't have to walk far. New rear fins have been designed for K flights. We will see how that does.

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Finally got around to flying this thing with the new fins. Did 10kft with a k820 blue. Still had some wiggle though, too small correctional coefficient.
 
Straight North, landed in the grass. Yes, it was VERY hot. Hence, you didn't see me come out of my trailer much.

It flew, but not like I wanted. It is a scaled down version of Spikey 5. The lower long moment and smaller correctional coefficient puts the natural frequency close to the roll rate, which is bad. I must have a messed up fin, can't shake the roll. Time to de-fin that lower section and rebuild it.

That flight also had a test payload. In addition to my standard TeleMega/EasyMini/Camera setup. I ran two other EasyMini's to validate them before integration and flight on another vehicle. The data looks good, but still need to do a numeric comparison.
 
I have started working on Spikey 3 again with a new plan. Here are a few things that have happened since I last posted.

Built a new tail section, 75mm minimum diameter. 8lb rocket on an M3700.

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Great flight to about 25kft @ Mach 2.2.

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Next flight didn’t go so great. Forgot to tighten a lock nut. The drogue unscrewed at 9kft and dropped from there. I recovered most of the mangled vehicle, the Playa ate the remainder.

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Ok, so that brings the thread to the present. Like any reasonable rocketeer I will try again. This time with 28kNs stuffed into a two stage 3” rocket. ;) This should be interesting.
 
Ok, so that brings the thread to the present. Like any reasonable rocketeer I will try again. This time with 28kNs stuffed into a two stage 3” rocket. ;) This should be interesting.

Damn dude... you've never done things half way. Will there be a build thread for that one?
 
This is my kind of rocketry! Way to push the limit dude! I want to do a 3 stage minimum diameter rocket that has 2 O3400s and the final sustainer that is 3" and has an M2245. My design is simming to over 150,000 feet :eek: Unfortunately I don't have the money to do this, as the motors alone would cost about $3000.
 
This is my kind of rocketry! Way to push the limit dude! I want to do a 3 stage minimum diameter rocket that has 2 O3400s and the final sustainer that is 3" and has an M2245. My design is simming to over 150,000 feet :eek: Unfortunately I don't have the money to do this, as the motors alone would cost about $3000.

The secret to doing 3-stage rockets is to buy the first set of motors, but then only have the first one actually fire. Then, you spend another K and try again the following year. Really helps to keep the cost down.

As for RFO, what the heck pair of 3" motors would give 28KNs? Chris, this is just wrong. Your shop will forever be known as the dark side.

Jim
 
So I was about to respond to the prior post, “This guy Jim can help with the three stage”, and you appear. Like a rocket genie...

The motors are long and erosive.
 
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