Martin Mars Build Thread (ivansplans.com)
 

Lots of info on these over at RCG, but I've not seen one here, so why not.

Just love watching videos of these dropping water in their role as fire fighters operated by Coulson Flying Tankers, from British Columbia, Canada.

This one spans 10 feet and weighs about 10 pounds. I'm going to use 4 outrunners for power, and hope to modify the design to pick up and drop water.

Here's the beginning of one hull side, made of mostly 1/4x3/16" balsa sticks. Ivan's designs are very light so they can fly slowly and realistically.

RE: Martin Mars Build Thread (ivansplans.com)
 

scribed,, neat project

RE: Martin Mars Build Thread (ivansplans.com)
 

Subscribed.... Saw the plane flying out of Shasta Lake California a few years back.

Awesome

Don

RE: Martin Mars Build Thread (ivansplans.com)
 

Keep us posted as you go along. How did you become interested in this plane? Where did your plans come from-Ivan direct or a plans supplier?

RE: Martin Mars Build Thread (ivansplans.com)
 

Keep us posted as you go along. How did you become interested in this plane? Where did your plans come from-Ivan direct or a plans supplier?

RE: Martin Mars Build Thread (ivansplans.com)
 

Looks like a good start-keep us posted in your progress!

RE: Martin Mars Build Thread (ivansplans.com)
 

They're down to only Mars mars now....the other has been painted in US Navy colors and donated to a museum..having reached the end of its useful life..

[link]http://www2.canada.com/albernivalleytimes/story.html?id=a0d7a708-f13e-485c-8137-2b83fc6767ca[/link]

Ivans planes fly very nicely if they are kept light......

RE: Martin Mars Build Thread (ivansplans.com)
 

I started building and flying seaplanes very early in my RC career, and I think I stumbled across the Mars during a Google search.

I bought the plans from Ivan. Only way, far as I know. His email address is on his website, ivansplans.com and he'll send you a list of the prices via email. He takes paypal.

I read the story on the Phillipine Mars. Mixed feelings about that. On one hand, I'm glad that she's maybe going to end up somewhere she'll be preserved and taken care of. On the other, I hate to see the old birds get retired. Hearing four 3350s crank up in person is like listening to a symphony.

RE: Martin Mars Build Thread (ivansplans.com)
 

This is great fun during the worst of the winter here. Cutting and gluing sticks. It's something I can do in the morning before I'm completely awake.

Nearly messed up. Saw a pic on another build that lead me to believe I could do the fore and aft hull sections separately. As you can see in the pic, I mended my ways. I did have to slide the ceiling tiles off the ends of my build table, but NBD. This is one big momma.

The forward section of the hull is straight on the top, between F1 and F10, so I think I'll join the two halves upside down, and just hang the upswept aft sections off the end of the table until I'm ready to join them. I'll be able to get all the bottom pieces and longerons onto F1-F10 while it's upside down and straight on the table, and that should help a lot.

RE: Martin Mars Build Thread (ivansplans.com)
 

One side completed (except for the sticks that go on the outside.)

I plan to build the other side right over the top of this one.

Looks like joining F1-F9 while the sides are inverted will work. Should be able to do all the former bottoms and the keel for that length of the hull.

RE: Martin Mars Build Thread (ivansplans.com)
 

Just curious how long is the side you just built?

RE: Martin Mars Build Thread (ivansplans.com)
 

69 inches.

Got most of #2 completed today. Should be able to start joining them tomorrow.

RE: Martin Mars Build Thread (ivansplans.com)
 

Oh boy. This part scares the heck out of me. F4 thru F8 are the same distance apart at the top (170mm) and the bottom (216mm) as measured on the plans top view. Taking angle measurements on the front view of the formers (none are the same) sorta yields a 5 degree tumblehome. So.......... You see it all below. I set my miter on the disc sander to cut 5 degree slants at the ends of the crosspieces, and notched my protractor so that it would sit flat on the board and give me a consistent measurement, port and starboard. (When the sides are equally slanted, I see 4 degrees, but that's because the protractor is not sitting on the datum line, it's about a quarter inch off the table.) Anyway, it all looks pretty good. I have a centerline down the work board, and am lining up each top crosspiece on that to make sure it all stays straight. Thanks to Ed Westwood for that tip. Always have a centerline, Ed said, no matter what you're trying to do.

Now, if I can just keep from blundering into all that stern hanging off the table, everything should be OK...........

RE: Martin Mars Build Thread (ivansplans.com)
 

OK Bob, I have to ask,, what does it get sheeted with?

RE: Martin Mars Build Thread (ivansplans.com)
 

Bob I hope you don't take offence to a suggestion. I purchased a couple of damaged interior wood doors from Home Depot or Lowes. They work great and most time they are very flat and only have a hole or scar on one side which yoy will turn down. Makes a great 7' table top! Good work so far.

RE: Martin Mars Build Thread (ivansplans.com)
 

10 ft wingspan and 10 pounds I bet it's monokote.

RE: Martin Mars Build Thread (ivansplans.com)
 

Yeah, she's mostly open framework covered with Monokote. I'm probably gonna need two 25 foot rolls of Insignia Blue, as I decided to make her a USN version.

RE: Martin Mars Build Thread (ivansplans.com)
 

Roger: thanks for the tip on the doors. My table is steel, five feet long, perfectly flat, and it was free. (My son in law was clearing out his office in St. Louis and didn't want it.) This is really the first time I've built anything where it would have been nice if it was six feet long. The hull sides are the only item where that's an issue. The five footer should be fine for the rest of the project.

Once I got enough bottom cross pieces in place to do some checking, it became obvious a twist was manifesting. Using the square with the cross piece centerlines made it easy to get everything lined up using diagonal braces. Once the sheeting's on, I'll be able to hack them out. Anyway, it looks right to the eye, so I must not be too far off.

I think I'm going to sheet the entire hull. The pic above made me realize how little weight would be added by covering the gap between top and bottom sheeting with 1/16 balsa.

RE: Martin Mars Build Thread (ivansplans.com)
 

Did you borrow the photo? She's really big compared to the picknic table. I think you have made a wise decision about sheeting the entire side. I've wanted to do a mulit motor plane for a time now and this one looks grand. I'm watching over your shoulder every move with this one. I'll be asking questions about the wiring and control systems as you go later in the build-I hope I want be a pest.

RE: Martin Mars Build Thread (ivansplans.com)
 

Bob,
It would seam to me some sort of permanent bracing or gussets will still be needed,, the sheeting alone wont stop the box from wracking. Plans don't show anything like that??

RE: Martin Mars Build Thread (ivansplans.com)
 

Roger: The Mars on the picnic table is Ivan's, I think, or one of the other guy's that lives near him. Feel free to ask away about anything at all. RCU helped me tremendously, so I'm happy to share in return.

scale: I was thinking earlier about the lack of rigidity in the hull. Even with all the pieces on it now, it twists very easily, and I see no way that the sheeting will improve that. I had the same experience with a BUSA 1/4 scale DR-1 kit. The fuse aft of the cockpit is built the same as this bird, and it was so twisty that I added a lot of 1/4" balsa gussets in the various corners. Probably end up doing that to this one. Flexible airplanes are scary in flight.

I did find this pic of Philippine Mars after Coulson repainted it.

RE: Martin Mars Build Thread (ivansplans.com)
 

Getting the bow curves correct was tedious, as I forgot to kerf cut the insides of the longerons and had to do that with a dremel cutoff wheel after the fact. With the help of various temporary braces I was able to get it looking OK.

Put the "V" bottoms onto the bulkheads from F1 thru the step- now she's starting to look like a boat!!

A pair of 2x4 chunks worked to space the forward hull off the board so that the upswept aft section could be pulled together over the centerline and the various cross pieces installed. The aft ends are not even when pulled together over the centerline. Don't know why. Everything looks straight, anyway.

I think I'll sand it and sheet the bottom once all the cross pieces are in, then flip it over to finish the upper surfaces.

RE: Martin Mars Build Thread (ivansplans.com)
 

How much was the aft sides off-the photo looked great, on the line,it looked perfect. You may be like I am, that sort of thing bothers me until I figure it out or settle for "close enough".

RE: Martin Mars Build Thread (ivansplans.com)
 

Just curious, how much was the aft side off? The photo "on the line" looks great. The kerf cutting looks tedious.

RE: Martin Mars Build Thread (ivansplans.com)
 

Just another thought-1/16 ply to cover the forward bottom, would not add much weight and much more durable. I have a source for 2' x 4' sheets resonable.