There He Goes Again.........
So I started doing some sketches of how I would revise Jay's design for a lower-profile motor and an 850~1200mah battery. :confused2: Lo and behold, I came up with a low-profile design that uses 1" foam and the same motor/prop/shaft combination. :banana: The plan view is essentially the same except I rounded the nose enough to make it just under 350mm. The profile view resembles a Frisbee with a flat stern. I think I will make 3 templates from 1/4" MDF (the upper hull, the lower hull, and the hatch) and use my table-mounted router to cut the foam to shape. That way, I can make as many as I want. The rest is simple, some 1/32" styrene sheet, and I'll cut some motor mount parts from 1/16" ply in the "extra" space on a sheet from my rigger project.
This arrangement will allow me to get the motor lower in the hull, reduce the driveshaft angle (it will exit at the top of the step), and greatly reduce the profile. It's going to look like a little flying saucer zipping around the pond. :spy::lol:
UPDATE: I have some 1" pink foam; I have some MDF to make templates; I have stuff to make a 1/32 wire drive; I have motor couplers; I have motor mounts. When I finish all the other projects, I'll start this one. The motor/coupler/receiver/ESC/propeller will all go into the new one. :cool2: I may leave the old hull/driveshaft/motor mount/servo/rudder intact for future experimentation, but it will definitely be relegated to the "Retired" pile.
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I Got Some Ni-Chrome Wire Today....
..... and I cut the lower hull pieces. The cutting fixture I made worked perfectly. :banana: As long as I had my light table (a.k.a. Uber-flat surface) out for the Mini Rigger project, I thought I'd glue up some MPR hulls as well. I'm using expanding polyurethane glue as I think it's just the ticket for foam. Here's the first of two I plan to do.
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Cool-Looking or Dorky-Looking; You Decide!
Here's some photos of the first MPR roughed-out.
Whadda ya think?
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So How Do You Mount a Rudder On a Foam Transom?
I gave this some thought and came up with this idea: A small block of wood, drilled and tapped for the rudder mounting screws gets glued into a square hole in the transom. The result? Rock-solid! The other prototype I'm building has a 1/32" styrene transom glued to the foam. On that one, I'll add an inset plywood doubler on the inside, then drill and tap the mounting holes. Thus far, I think this is the easiest method, but we shall see.
The Worst Covering Job.... EVER!
On the first Pool Racer I built, I applied EconoKote low-temperature film. There were some wrinkles here and there, but not too bad. I also had some issues with the film not sticking along the edges. So I thought I would use some sanding sealer on this one to give a better edge for the film to stick to. The problem was, in so doing, there was no place for the air to escape as I was applying the film. Trying to iron it down, just heated the air under the film making the bubble bigger; or if I did get it to stick, it was just a bunch of wrinkles. Trying to heat up the iron to help the film shrink just melted the foam.:doh:
Oh well, lesson learned. I have a bunch of foam hull pieces. I'll give this one a test-run, then replace the hull.
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Amazing 12-Step Recovery Program Reduces or Completely Eliminates Wrinkles!
Just apply this special cream for a week..... :olleyes:
No really, I got to thinking that I couldn't show up in public with the covering job I did, even if it was just for testing. One of the contributing factors for my crappy covering job is I tried to do too much with a single sheet to eliminate seams. I decided to re-cover it it in a number of smaller pieces; but what about all the seams? Hey! If Eddy can do it to a guitar, I can do it to the MPR. Yeah, it looks sort of cartoon-ish, but it's totally fitting. The covering on the hatch wasn't too bad, so I left it as is.
Behold, the results of the recovery:
Wouldn't You Know it.......
I finally found a motor/prop combo that works well in the MPR and now that motor is discontinued. :Sinking: At least I have another on order. The MPR was so easy to overpower, I wonder what readily available motor will work in it. :confused2: I really need something around 75 watts maximum.
Now, I'll have to do more experimenting........ AGAIN.... :cursing:
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MPRs Coming Out Of My Ears
Lots of room for experimentation (see first photo). I may have the motor/coupler/driveshaft issues solved. I'm looking for a solution that anybody can do and it has to be CHEAP!
The "Clown" MPR uses a 1/32" wire straight drive. It's a bit of a PITA to build and requires specialized machine tools. I have a line on uber-precise 0.1247" stainless steel shafts which should be just the ticket and about $7.50 each if I buy a sufficient quantity. A 5/32" brass tube will make a perfect stuffing tube. I found aluminum couplers on eBay for under a couple of bucks each that can be reamed out to fit the 2.5mm shaft of the cheap outrunner I am going to test out. The reaming requires specialized machine tools but the setup time is minimal and I can make as many as necessary in 30 to 45 seconds each after the setup is done.
My goal is to design something that can be built for under $100 using all-new equipment. If you're like me, you already have a bunch of stuff on the shelf that could cut build costs in half.
Send me a note if you want full-sized *.pdf files of the foam and 1/32" styrene parts.
When I was originally building the first MPR, I was going to put a decal on it that made people think of pancakes, because the hull was rather flat like a pancake. I thought the Patron Saint of Pancakes would be fitting (see second photo). Now that it has a more clowin-ish appearance, I may put a different decal on it (see third photo).