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Old Feb 18, 2012, 10:05 PM
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**neons**'s Avatar
USA, MA, Swansea
Joined Mar 2003
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Build Log
Martin XPB2M-1 Mars 1943- Scratchbuild

Last year 4- 2011 I scratchbuilt the Kawanishi H8K2 Japanese "Emily". It was a 3 month project with plenty of interest. (http://www.rcgroups.com/forums/showthread.php?t=1417974)

This year, 2-2012, I have started the new build of the early version of the Martin Mars that had the twin rudder. I have the fuselage framing started. I am basing the model on Ivan Pettigrews plans.
You can contact Ivan by emailing him. Here is his email address:
ivanp@dowco.com

Scale 1/20
Wingspan: 120 Inches
Length: 72 Inches
AUW: 13 pounds. as I estimate.
Wing Area: 1515 sq. in.
Wing Loading: 15.7 oz/sq. ft.
Airfoil: Eppler 197 with NACA with washout built in on outboard wing sections.
Power: Hex DT-750 brushless. MAS 10x7 with opposite rotations Nanotech 4s 5000Mah 14.8v Lipolys

The model will not be true scale as there are modifications on the plans that are not exact. I am going to divert from the plans some to use a mix of Depron foam and wood with some carbon fiber also I am first going to upload some pictures and drawings and maybe some notes of this version Mars.

**Neons** Bob
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Old Feb 18, 2012, 10:05 PM
5,200 Led Lighted Bike-Bob P.
**neons**'s Avatar
USA, MA, Swansea
Joined Mar 2003
2,679 Posts
After all the trials were over the Mars XPBM-1 was redesignated for carrying cargo and personel. There was a problem with control of the plane with the twin rudders using the flaps. I guess it affected the rudders by disrupting airflow on landings. There was an R-1 Designation and a 3 later before the present JRM's flying as water tankers these days in Canada. I am concentrating my build on the XPBM series as I like the look it commands. Here are some more drawings of the JRM series for study. The tail is the most prominent change along with the gun turrets. When the JRM's came out thet added more power and new 4 blade props. So basically these drawings apply to the early versions also.

**Neons** Bob
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Old Feb 18, 2012, 10:47 PM
5,200 Led Lighted Bike-Bob P.
**neons**'s Avatar
USA, MA, Swansea
Joined Mar 2003
2,679 Posts
The Build Log is here. The plane has been finished. It was taxi tested and has not been flown at this time. The season has run out and I will try to fly her next spring. The video will be added after the flight here.

Log
http://www.rcgroups.com/forums/showt...5#post22206438

Taxi Testing
10 17 2012 Martin Mars Water Test (4 min 12 sec)


Updated 12-04-2012
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~
Maiden Flight
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~
9- 6 -2013 Martin Mars Maiden Flight (4 min 10 sec)


Update: Flew Sept.8, 2013 ........Another latest video - 5th Annual John Nicolaci Float Fly - Mars flight
9- 8 -2013 5th Annual J. Nicolaci Flo Fly - Martin Mars Flight #2 (5 min 19 sec)
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Last edited by **neons**; Sep 18, 2013 at 03:16 PM. Reason: Info Added
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Old Feb 18, 2012, 11:15 PM
5,200 Led Lighted Bike-Bob P.
**neons**'s Avatar
USA, MA, Swansea
Joined Mar 2003
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First off. There is another thread building the same plane in the JRM format by Rudderman a few years back. It is a very good build log if you follow Ivan's plans closely. As I mentioned I will follow some what closely. My plane will probably be slightly heavier. I am deiviating with different building materials here.
http://www.rcgroups.com/forums/showt...ght=ivan+plans

The framing was started with some fresh cut clear hard pine wood. I cut strips from 1/4inch thick pieces in 3 sizes. 1/4x1/4, 1/4x3/16, and 1/4x1/8th inches. Most framing was laid out with 1/4 square along the bottom longerons. The rest is mostly 1/4x 3/16inch. I used 1/8th inch balsa reching above the waterline. Progress went along good for the 2 days here.
**Neons** Bob
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Old Feb 19, 2012, 07:30 AM
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United States, IL, Joliet
Joined Jun 2009
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Iam sighned up Bob ,i can remember my solent fuse at this stage . joe
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Old Feb 19, 2012, 07:33 AM
Check your six
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Subscribed Buddy!
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Old Feb 19, 2012, 12:45 PM
5,200 Led Lighted Bike-Bob P.
**neons**'s Avatar
USA, MA, Swansea
Joined Mar 2003
2,679 Posts
I find a few measures do not match but I can build a plane from 3 view drawings so I can manage these plans easily. I found the nose off on measures but it will be ok though.
**Neons** Bob
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Old Feb 19, 2012, 01:34 PM
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Joined May 2001
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Hi Bob, I've added this thread to the Ivan Sticky. Will be interesting to see a twin-tail version.

Everyone must be tired of hearing it by now, but try to keep it light! Ivan's designs don't need any reinforcing. I've never seen a model built to his plans break from weakness, but I've seen a few that didn't fly so well due to excessive weight.


Luke
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Old Feb 19, 2012, 02:27 PM
5,200 Led Lighted Bike-Bob P.
**neons**'s Avatar
USA, MA, Swansea
Joined Mar 2003
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Luke, Thank You. That will be nice to link relatives together for others to see a different version. Although I will have a some what different materials in the construction, there may be some that accept it and the true all wood nostalgic people may frown on it.

**Neons** Bob
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Old Feb 19, 2012, 04:52 PM
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Quote:
Originally Posted by **neons** View Post
Luke, Thank You. That will be nice to link relatives together for others to see a different version. Although I will have a some what different materials in the construction, there may be some that accept it and the true all wood nostalgic people may frown on it.

**Neons** Bob
Foam ,wood or balsa,paper we dont care as long as it floats and flys Bob. Who's frowning ! lmao joe
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Old Feb 20, 2012, 12:25 PM
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United Kingdom, England, Wigan
Joined Jul 2011
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i have pulled up a chair...

will be watching this one over the top of my Sunderland build

David
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Old Feb 20, 2012, 09:53 PM
5,200 Led Lighted Bike-Bob P.
**neons**'s Avatar
USA, MA, Swansea
Joined Mar 2003
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V hull formers , Water Rudder, Modified tail sector

David. Welcome. There are days I move along and then some that drag as I figure out how I want to do something. Of course there are days I just go fly. I am just guessing and I think a rough estimate would be 3 months. Enjoy. Pass the popcorn.

Luke, Thanks.
I will be making modifications as I build my plane. The plane is built light as Ivan designed it. He has a nice floater as seen in all his videos. Great flying. I will probably be flying in some windy weather here in the warmer months. 90% of our days are windy about 18MPH in mid day and all afternoon. See my Avatar and look at my Emily and you see maybe 15mph and choppy waters in fluctuating breezes. I think a slightly heavier plane is acceptable for me.

Here is what I did in the last couple days. I curved the nose section by making fine slits in the sticks and pinching in the sides to give it some round shape . The plans were showing flat. The photos look round. I laid all the V formers in place. I used a 1/4 x1/4" square for the keel. Tied it down in the nose and bent in the curve and CA'd in place. I put in a support gusset behind the plywood nose bulkhead. Next I installed gussets all along the chine corners inside. There just was not enough glue contact in that sharp angle. Here is a weak point I strengthened. Another point of stress that I wanted strengthened was the area under the wing trailing edges on the fuselage. I have seen many planes break right at that area in a crash including mine. These were all gusseted also.

The next thing I wanted is a water rudder that would conform to the original profile lines. I made the mount and cutout a rudder from the existing hull taper on the bottom. Using brass tube and a shaped copper end I soldered and then inserted that tube end into the hollow rudder. The outer housing was fitted into the hull and then a new former was installed with another gusset. The curved outer balsa hull shape was glued in place also. The bottom of the hull and rudder will have a thin plywood flared in place. All I have to do is solder a copper servo arm on the rudder post when ready.

The rear picture shows the rudder dropped in. There were additional formers installed in the tail section. I changed the keel angle to a slow curve rather than the straight run on the plans.as the real photos show. The stern post was widened to accept a tail gunner station. It will also help the elevator seating too.

Next I am looking at getting the elevator and rudder cables in place. The side sheating will go on first so I will also get better gluing access also. Then the bottom sheeting can be done.

**Neons** Bob
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Old Feb 22, 2012, 01:02 AM
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Excellent I'll be following along...
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Old Feb 22, 2012, 07:41 AM
PS1
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Quote:
Originally Posted by **neons** View Post
David. Welcome. There are days I move along and then some that drag as I figure out how I want to do something. Of course there are days I just go fly. I am just guessing and I think a rough estimate would be 3 months. Enjoy. Pass the popcorn.

Luke, Thanks.
I will be making modifications as I build my plane. The plane is built light as Ivan designed it. He has a nice floater as seen in all his videos. Great flying. I will probably be flying in some windy weather here in the warmer months. 90% of our days are windy about 18MPH in mid day and all afternoon. See my Avatar and look at my Emily and you see maybe 15mph and choppy waters in fluctuating breezes. I think a slightly heavier plane is acceptable for me.

Here is what I did in the last couple days. I curved the nose section by making fine slits in the sticks and pinching in the sides to give it some round shape . The plans were showing flat. The photos look round. I laid all the V formers in place. I used a 1/4 x1/4" square for the keel. Tied it down in the nose and bent in the curve and CA'd in place. I put in a support gusset behind the plywood nose bulkhead. Next I installed gussets all along the chine corners inside. There just was not enough glue contact in that sharp angle. Here is a weak point I strengthened. Another point of stress that I wanted strengthened was the area under the wing trailing edges on the fuselage. I have seen many planes break right at that area in a crash including mine. These were all gusseted also.

The next thing I wanted is a water rudder that would conform to the original profile lines. I made the mount and cutout a rudder from the existing hull taper on the bottom. Using brass tube and a shaped copper end I soldered and then inserted that tube end into the hollow rudder. The outer housing was fitted into the hull and then a new former was installed with another gusset. The curved outer balsa hull shape was glued in place also. The bottom of the hull and rudder will have a thin plywood flared in place. All I have to do is solder a copper servo arm on the rudder post when ready.

The rear picture shows the rudder dropped in. There were additional formers installed in the tail section. I changed the keel angle to a slow curve rather than the straight run on the plans.as the real photos show. The stern post was widened to accept a tail gunner station. It will also help the elevator seating too.

Next I am looking at getting the elevator and rudder cables in place. The side sheating will go on first so I will also get better gluing access also. Then the bottom sheeting can be done.

**Neons** Bob
...Hi Bob / Hi joe and all...
....God!...This it is Super structure , that beautiful and should lightly
( Pretty since still not finished) ....Very nice work..! Bob
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Old Feb 22, 2012, 08:51 AM
I fly Helis too!
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