JMcRae

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Hi all.

Just thought I would post my build of a Martin PBM Mariner designed by Keith Sparks. I recently got into seaplanes and floatplanes a couple of months ago the reason being is that is now 110 degrees by 11AM and the only way I can stand flying RC is standing waist deep in a lake (that and a day at the lake keeps the fiancee and dog entertained). I must say that it is the most fun I've had in RC yet. So far I have a 40 size trainer and a 20 size GP Cub on EDO floats I shaped and sheeted. I am happy with both but I wanted something BIG and scale. This plane fits the bill as it is the biggest plane in my hanger yet with a 101" wingspan and a fuselage big enough to fit a toddler in . I ordered the plans from MAN a few weeks ago and got them yesterday. Amazingly enough, after about 4 hours of work, the fuselage is almost ready for sanding and glassing. I began the project this morning by picking up my foam at a company here in Phoenix called HPI. The coolest part about them was that they GAVE me enough 4" thick white foam for 10 wings!!!! So far, finding the foam has been the most time consuming part of the project. After 4 hours in the garage I had one huge, ready to be sanded and glassed, fuselage (or hull if you want to get nautical on me). Try doing that with balsa and ply!!! This is my first foam plane and all I can say is "Why didn't I think of this sooner?". The construction meathod is basicly cutting out 2" thick blue or pink foam cross sections and gluing them together. I made a vertical hot wire cutter (kinda looks like a scroll saw) for three reasons. 1-I'm not too worried about the finish of the rough cross sections (that's where the sanding fun comes in tomorrow). 2- Cutting out 38 cross sections with a scroll saw would probably leave me with a migrain from hell. 3- I can't afford a scroll saw []. Anyways, here's some pics and there will be more to follow tomorrow.

Jimmbbo

Great! I love the PBM and looking forward to seeing your build!! You going to post pics?

Cheers!

Jim

JMcRae

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For some reason my pics won't upload. Any ideas ?

JMcRae

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Alright, I'm about ready to kick my computer!!!!! For some reason I can't get the pics to upload even after it says it has been done. Anyways, today I got the hull sanded from the bow to the first step. This section is about two and a half feet long and I think my biceps have grown about two inches in the process. But it is definatly starting to look like an anphibian!!! On a negative note, I discovered that 3M changed the formula even in the old style label and as a result, I have a few sections to fill with some spackle as it melted some of the foam (D@mnit 3M!!! Why fix something when it isn't broke!!!). I also decided that it is probably best to separate all of the sections and rebond them with either epoxy or Gorilla Glue. This will probably take about an hour so I'm not to worried about it. Learning curve I guess but what the hell . Anyways, I'm going to try to upload the pics again.

JMcRae

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Cool! I got them to upload. BTW power will be from twin (obviously) OS 40 FP's with Slimline mufflers. I decided to go two stroke because four stroke valve covers won't fit inside the cowls (big eyesore to me) and, more importantly, I have two 40 FP's without a home or, rather, a home that won't miss them. I'm also planning to do flaps, retracts (if I can get ahold of a mill), and, most entertainingly, BOMBS!!!. I haven't decided whether the bombs or torpedoes will be in the engine nacelle as on later models, or between the nacelles and fuse as on earlier models. I'm leaning towards external as it will be a lot easier to set up and, more importantly, reload . I am also going to use a single 50 oz, thats right 50 oz, tank in the fuse with a Perry's fuel pump. Running on 40 FP's it should fly clear across Arizona on a single tank. I'm also planning on using two 1500 MA batteries connected in series to provide power to the radio gear. Basicly, with this setup, I'm hoping to be able to fly all weekend and never have to touch it except to start it. Anyways, more to follow tomorrow.

JMcRae

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make that parallel on the batteries

Kmot

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Wow! This is sooo cool! Thanks for posting the pics and the build info. I will be following your progress with enthusiasm.

JMcRae

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Today I made a little progress. I got most of the fuse hollowed out using a bow cutter I made a few weeks ago. Although not perfect, I think it is good enough. This was really time consuming as I was making templates as I went. I also separated and rebonded all of the useable cross sections with Gorilla Glue. The reason I use this was because as it dries it expands and there were a lot of areas where the 3M melted the foam leaving voids to be filled. I also discovered that four sections right in front of the second step are unuseable due to the damage from the 3m. This is a little discouraging and tomorrow I will have to cut new sections. Lesson learned I guess. Anyways here's some current pics of the sanded and hollowed bow section.

Kmot

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I was wondering about the hollowing part.........

So, will you now add some sort of wood bracing inside?

JMcRae

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No. There's no wood in the fuse. After I'm done sanding it will be glassed with 3 or 4 layers of .5oz. I decided to hollow it out at this stage from the advice of another PBM builder I've been emailing back and forth. He assured me that the foam would still be rigid enough for sanding hollowed out. He was right. Although I only got to spend 30 minutes on it today, I got a decent amount of sanding done. Also, the Gorilla Glue worked perfectly but I have a few seams to cut into as a little wicked through to the outside. I'll then fill them with lightweight spackle and sand them smooth. Sanding foam with glue ridges doesn't really come out too good. I just wished I had used it first instead of the 3M. Even without glass, I'm surprised how strong the hull is. I don't think I'll be able to spend any time on it tomorrow as I have a checkride on Wednesday and I have some studying to do[X(]. More to follow.

NickC5FE

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Jesse, absolutly superb bro-man. You are moving right along. I think that you may have sold me on building one of these. Nick

JMcRae

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I told you so!!! I think at this point I've got $22.00 into the project. Hope you feel better Nick.

NickC5FE

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Thanks jesse, now do me a favor....answer the dam# phone from time to time. Nick

Semi Retired Aviator

Looking good Jesse. It doesn`t seem so long ago that mine was there. Fuselage is long finished, and the wing is balsa skinned waiting for the glass, but vacation starts next week, so it waits another month.

You did a much better job of hollowing the sections than I did. Mine are a touch untidy.

Make sure the finish is as smooth as you can get it before glassing or there`ll be a lot of extra work. I used a light water based filler, and then finished it off with fine sandpaper before the glass went on. I`ve had almost no filling over the glass.

I intended going electric, but the setup was going to be about US$1200 for everything, so that`s been ditched. For that sort of loot I can buy another YS53 four cycle (I already have one), or two 2 strokes, a Hangar 9 Corsair, and half the electrics required for the mariner for the Corsair, a Rx, fistful of servos, and still have change. Easy decision, 2 strokes on the Mariner. The number of batteries really pushes the price up for electric power.

I was looking at an ad for RCV engines (I think that`s it). They look like the prop shaft is coming out of the glo plug; very small frontal area, so should easily fit in the cowls. Anybody know anything about them? I think they may be four cycle too though, and therefore much more expensive than conventional 2 strokes. I`ll take a look at the web site.

$22 isn`t much Jesse, but get ready for it; it IS going to cost a lot more!!

26ray

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Hey Japan Flyer, The RCV engines are nice. I have had several of them. A bit heavy, but solid construction. Check them out at www.rcvengines.com they have all the info you need on the site.

- NICE looking fuse. Is this a kit or what ? How do you shape it so nice. I cant wait for you to post some more pictures of it.

JMcRae

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Post some Pics JapanFlyer. I'd like to see how it came out. I was reading in MAN that the RCV motors have a 2:1 gear ratio so you can run scale props in a lot of applications. I know you reduced your plans so I'm guessing your going to run .25's and I'm not sure they make any that small. Acording to my measurements though, 40 FP's are going to fit inside the cowl without any holes (hopefully). I too have been considering jumping on the electric bandwagon but it is still so darn expensive. I have a 1/12 scale F-14 (swing wings, retracts, tailhook, flaps, and everything else I can think of) about 3/4 done but I don't have any motivation to finish it because it needs almost two thousand dollars in electric gear. Seven hundred for just the battery pack!!!!!! Oh well, maybe one day when I'm a captain like Japan Flyer . Also, I haven't gotten much done lately as I've had a lot of studying and flying to do but I'm hoping to sneak into the garage tonight for a couple of hours and get the rough sanding done on the hull and possibly cut my wing cores.

Semi Retired Aviator

Well I`ll try to put some pics up Jesse, when I get back home in a couple of days. I`ve never done this before (posted pics) so there may be some homework to do.

I`ve taken a look at the RCV site, and they don`t make them small, so it looks like a couple of OS .46`s, and they`ll be more power than I need, but hopefully I can swing a slightly larger prop for scale looks. I already have one. It might just stay within the cowl, but won`t be too obtrusive if not.

Another tip Jesse, if you have any ridges/valleys on your wing core because one of you moved to hotwire too fast/slow, make sure you sand them out before you skin it with balsa, because if you don`t, they will cause the balsa to follow the foam precisely. That would apply whether you use the waste foam to hold the balsa down while curing, or vacuum bagging method.

26ray, as Jesse mentioned, it`s a Model Airplane News plan. Thanks for the info on RCV engines.

If you`re reading elmshoot, how are your two mariners coming along??

JMcRae

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Where are you now? I've seen a lot of senior (as in seniority not age) pilots in the parkflyer forums who actually pack up their projects in a bag and take them with them when they have long layovers. There was even a guy converting a Guillow's P-38 who drags it everyehere with him. Beats watching TV in a hotel room . As for the wing cores, I've definately cut a few back in my slope racing days so I'm not to worried about it. I'm also considering just bagging the wing instead of using balsa but I'd have to build a new vaccum bagger as I threw mine away years ago.

JMcRae

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As for the sanding, anyone with a longboard and a soft touch can get foam to come out flawless from what I've experienced so far

Semi Retired Aviator

Two out of every three nights on the road are spent in Tokyo, and the attached pic shows what Tokyo is like; not everywhere, but parks and pools are like this. Just the place to go and relieve some stress!!

So as you can see, taking a park flyer is out of the question, unless I flew it in my hotel room,and they're small in Japan. Everything here is in miniature.

Kmot

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[X(][X(][X(]

JMcRae

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Well, last night I didn't get to spend as much time on it as I wanted. The only things I got to do were to cut the new cross sections that the 3M melted, six in all, and glue up the sections including the tail boom. I also got the cores marked for cutting with my sawsall or 7" rotary. Hopefully tomorrow after yet another checkride [X(] I'll get to spend 3-4 hours on it depending on what the missus has planned for the evening. I'm shooting to have the hull ready for glassing by sunday night except for fitting the cockpit and tailgunner blister. I also finally got around to sending off a money order to Sparky, the designer, for all of my plastic parts. More to follow and I'll post some pics when I'm done sanding the hull.

JapanFlyer- So how often do you get to swim laps? . I'm not even going to mention what I think most of the pool is filled with [X(][X(][X(]. Anyone care for a dip in my septic tank?

JMcRae

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JapanFlyer. How about a couple Wankels (rotary engines)? I think OS makes one in a .30 size but they are pretty pricy from what I remember. Plus they sound pretty cool. Think of two RX-7's next to each other[8D].

retransit

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Are you trying to say the water is thick with urine?

Bob

JMcRae

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Thats what I was trying for . Anyways, now for some great news. I passed my CFI (certified flight instructor) checkride !!!!!!!! It was a ten hour oral test followed by a four hour flight test [X(]. Not very fun!! Also, the examiner I flew with is a national aerobatic champion and, since he liked me, he's going to take me up in a Pitts S2C (the $220k brand new model) for an hour for the cost of fuel!!! I'll post pics of that when I do it in two weeks. Hopefully I can get Pantherflyer (Nick) to fly a spotter plane and work my video camera. The good thing about being done with my CFI rating is that I'll now be able to spend a lot more time on the Mariner. I'm hoping to have it done within a month or so. I'll post pics tomorrow of my progress.