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  #1  
Old 07-22-2020, 09:22 AM
john ager john ager is offline
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Join Date: Sep 2019
Posts: 38
Default Estes MAV Lander build

I haven't done a build thread on these forums in a very long time but I figured I'd give it a shot again. Decided to do a simple build with just a couple of quick modifications.

I was really on the fence with the MAV. When I first saw the rocket I was hoping it would be larger. Initially I had something like the Alien Space Probe in mind. Looking at the early pics I was hoping that the fins were wood as well. When the model was released I was disappointed with its size and the number of plastic parts. I also couldn't swallow the price for such a simple small rocket. About 2 months ago I was surfing the web and found one for sale cheap and took the plunge. Overall I’m happy with it but still wished it was a harder build. Might have to upscale this one as it is a cool design.

Photo 1 - As you can see in photo 1, the kit is very basic. The Nosecone is specific to this model and very nicely done. It comes painted and has nose weight added. The body tube is standard Estes tubing and comes prewrapped. The lower body section / motor mount is plastic with a screw on motor retainer. The fins are soft plastic and it comes with 3, peel and stick decals. The parachute is 18 inches and the shock cord is premounted to the inside of the tube.

Photo 2 - The biggest change to this rocket is going to be in the motor mount. I have hated these plastic fin unit/motor mounts since the first time I flew one. After the 4th or 5th flight the plastic above the motor was completely burned, brittle and melted and eventually failed. At that point I decided that I'd never build one stock again. In photo 2 you will see that I'm adding a section of BT20 for a motor tube, an 18mm thrust ring and a BT20/50 centering ring to the build. Not pictured is the Kevlar line and elastic that will replace the stock shock cord.

Photo 3 - In this photo you can see the modifications required to fin can to get a motor tube to fit inside. I first opened up the top hole to allow the tube to pass through. This gives me a clear path for the ejection charge so it won't melt the plastic. Next I needed to trim back the vertical supports to allow for a centering ring to fit. Finally, the lower portion of the mount inside the threaded area was opened up slightly to allow for the motor tube. Be careful here as you don't want to take off too much. Placing the motor tube with a small amount of epoxy will add back in any strength you might lose.

Photo 4 - I built a standard 18mm motor mount with an internal thrust ring and a BT20/50 centering ring positioned just below the plastic upper ring. A 12in piece of 200# Kevlar was then wrapped around the motor tube just under the centering ring to give me a solid place to attach a shock cord. Here you can see a quick test fit.

Photo 5 - In this pic you get an idea how this will fit together. Here I placed the two motor mount sides together for a quick test fit to ensure nothing was in the way.

Photo 6 - This is as far as I made it as I need to let everything dry. I slid the fins into the can and attached them on the outside with thin CA and let that dry for a few minutes. Once dry I mixed up a small amount of 30 min epoxy and coated the attachment points on the inside of the fin can. The motor tube was also attached using Epoxy and the motor halves were glued together and let dry.

I'll pick this build up later today and time permits. From this point forward it's pretty straight forward.
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Last edited by john ager : 07-22-2020 at 11:30 AM.
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  #2  
Old 07-22-2020, 09:42 AM
mojo1986's Avatar
mojo1986 mojo1986 is offline
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Looking forward to this. Was construction already started when you purchased it?
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  #3  
Old 07-22-2020, 09:52 AM
john ager john ager is offline
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Quote:
Originally Posted by mojo1986
Looking forward to this. Was construction already started when you purchased it?


No. The kit was brand new in the bag. Just happened to find someone that didn't want it and sold it cheap.
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Old 07-22-2020, 11:14 AM
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LeeR LeeR is offline
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I am also building a MAV now. I too was a bit surprised at the size, it did seem larger in pictures. One correction — the upper tube is a standard paper BT-60 with paper wrap. The motor/fin unit is plastic as you say.
I am going “custom” with mine. I removed the launch “guide” and replaced with thin wood standoff and regular launch lug. I have also added a lot of styrene details onto the wrapped upper tube, and primered the entire kit in preparation for paint. Other than that, it’s stock.
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  #5  
Old 07-22-2020, 11:23 AM
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mojo1986 mojo1986 is offline
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Oh OK, I see now that the fins are one-piece injection moulded plastic. Did you apply the wrap to the tube, or did it come like that in the kit?
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  #6  
Old 07-22-2020, 11:30 AM
john ager john ager is offline
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Quote:
Originally Posted by LeeR
I am also building a MAV now. I too was a bit surprised at the size, it did seem larger in pictures. One correction — the upper tube is a standard paper BT-60 with paper wrap. The motor/fin unit is plastic as you say.
I am going “custom” with mine. I removed the launch “guide” and replaced with thin wood standoff and regular launch lug. I have also added a lot of styrene details onto the wrapped upper tube, and primered the entire kit in preparation for paint. Other than that, it’s stock.



True on the body tube. Correction made.

Thanks
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  #7  
Old 07-22-2020, 12:09 PM
john ager john ager is offline
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Quote:
Originally Posted by mojo1986
Oh OK, I see now that the fins are one-piece injection moulded plastic. Did you apply the wrap to the tube, or did it come like that in the kit?


The tube comes prewrapped.
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  #8  
Old 07-22-2020, 02:58 PM
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5x7 5x7 is offline
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I put one of these together also, I think the mod adding the motor tube is a good one if you will fly it a lot. Personally I didn’t like the clay showing through the nosecone and the hot glueed launch lug, but I do think it is a good value for the typical discounted price. The tube wrap is well done and eliminates the spirals and strengthens the tube so that’s a win. Most of the normal E2X/ARF color wrapped tubes that show the brown spiral under the color wrap are sad, and in bt20 and 50 are really thin and weak. I hope Estes propogates the convolute wrapped tubes through the E2X/ARF line and I would think they would keep more beginners as customers.
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  #9  
Old 07-22-2020, 03:42 PM
john ager john ager is offline
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To pick up where I left off. I had a few minutes around lunch time today to do a little more work on this one. Since the remainder of the project was pretty simple I figured I would be able to get through it during lunch.

Photo 1 - After letting the fin can / motor mount dry overnight I took a look at it and decided I didn't like the white plastic on the lower part of the rocket. I quickly wiped the motor mount and fins down and grabbed a can of Krylon Dove gray off the shelf as it looked like it would be a good match for the gray already on the wrap.

I masked off the upper portion where the fins slide into the tube and painted the entire fin can Dove Gray.

Photo 2 - After letting that dry in the blazing sun for about 10 mins I came back in and attached a 4ft section of 1/8 elastic to the Kevlar line. Next the upper part of the fin can was lightly sanded along with the inside of the body tube. A healthy amount of thick CA was used to connect the fins to the body tube.

While that dried I cut and replaced the stock lines on the parachute with 100# Kevlar lines. The Stock parachute is 18" and I'm not cutting a spill hole in it just yet as I fear that the landing pads are going to snap off on landing. While I was at it I also wicked in a small amount of thin CA behind the launch lugs to give them bit of strength.

Photo 3 - Final assembly. Nose is on, decals are on and it's ready to fly. I'm considering doing some additional detailing on the fins but I have a fear that they won't last past the first flight. If they do I'll do some additional painting but for now it's done and ready to fly.
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  #10  
Old 07-22-2020, 04:42 PM
SCooke123 SCooke123 is offline
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Turned out nice. I hope your first flight goes well. When do you plan its maiden voyage?
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