Mustang Fever

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Forgot to mention-

I'm going to make the tip floats retractable, using a pair of robart 1/8" wire mechanical retracts and a standard size retract servo. I'm also going to try and shave as much weight from the wing and the tail feathers as possible.

I looked at the video of yours in flight last night (again). What a great flyer, and you did a really nice job on the splash n go and the touchdown.

siddus74

Mustang,

I Agree with what your saying about the weight, keep the back as light as poss . . . consider sheeting the fuselage in 1/16th, that 64th ply is git to bend around thouse curves and the balsa is lighter. You may also wish to consider gluing 1/16th strips around the edges of the formers as I did, this with give you a larger surface to glue the sheeting to as the front will no doubt be sheeted in individual panels. I sheeted mine using individual panels and so did another guy I had correspondence with . . .

I will be very interested to see what you propose for the retracts . . . consider the weight though, thats the reason I didn't go for them. Mine was about 4.7lb ready to go aim for lighter, mines was still over built in places I feel . . .

When are you plans due to arrive? I have just order the Martin Mars plans from Ivan Pettigrew - thats next for me after my sunderland.

The sunderland is sheeted now, really please with it - used 1/16th not 3/32 and have tried to keep everything built up. I am aiming for 7lbs on that with any luck.

I am concerned that 60% of my models are boat planes now, what is it we find so facinating about them?

Below are a couple of pictures of an Ivan Mars in the bones . . .

Mustang Fever

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Simon:

I love those "bones" pix.

To offset the weight of the retract system, I'm using a single HiTec mini servo for the ailerons, with throttle cable linkage (Sullivan push cable). I'll be using the same types of cables for the elevator and rudder, and plan to mount the two mini servos all the way in the bow.

I'm with you on the bottom sheeting- 1/16 balsa is more than adequate for a model of this type, as long as the individual panels are supported at the edges. I did that on my 50% Mikulasko Arrow, and it really came out nice.

Looking at some of your build pix, it appears that there is plenty of room to put a battery hatch on top of the bow section, and that a flight pack might fit nicely in the "tray" that is formed by the basic structure.

The seaplane addiction is forever, I think. As far as I'm concerned, the biggest mistake Pan American Airways ever made was to stop using the Clippers on the Pacific route.

Mustang Fever

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Scotty:

Have you noticed that I keep getting you and Simon mixed up? [X(] (My two UK internet seaplane friends.) I'll try to keep you straight in the future. BTW- it was Simon's help that kept me out of trouble with my Laddie Mikulasko Arrow.

Anyway- the plans arrived today, and I just now ordered two of the 3-1/4" steel cowls from Sig. They're from an old AT-6 kit that they no longer produce. I reasoned I'd best get them right away before they run out, because I'm sure they no longer make them.

I'm going to go to the print shop and get the plans copied today, then I'll sit down with pencil and drafting tools and try to figure out how to modify the aft formers E through K so as to have the step at former D. That will put it real close to the CG. All my flying boats have had the step either slightly aft or slightly forward of the CG, and that location seems to work well.

siddus74

Mustang,

Yes I did notice, but thought it was no big deal so never mentioned it

Glad the plans turned up ok . . . some detail on the cowls would be good please as mu cat is at the stage of reliability where I may consider them also, especially if they are ali [8D]

Good thinking to ammend the plan / formers to ensure the step is in the correct place, iItoo may have tackled it in the same way if I have realised sooner that the step position was incorrect.

Just think I started mine this axact time last year! , amazing how time flys really . . . hoping my sunderland will be done soon.

Looking forward to seeing yours come together.

Scott

Mustang Fever

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Scott:

Here's the URL where the cowls are located: http://sigmfg.com/cgi-bin/dpsmart.ex...FV4.html?E+Sig

They are $3.98 U.S. apiece, plus only $7.98 U.S. shipping overseas. (Same as the continental US) Pretty good deal, I think.

Looking at the plans again, I drew a line from the bottom of the keel at former G, to 1/4" above the bottom at former D. I'll just flatten out the V angle on E and F so as to raise it to the line, and eliminate all of the aft keel piece that falls below the line. Then I'll make a "D1" to accept the bottom sheeting at the step. Should be fairly easy, and has the advantage of not changing the looks radically.

A question for you: I see that the vertical fin and rudder are really thick- 1/4"- do you think that going to 3/16 or even 1/8 would be feasible?

siddus74

Bob,

I think I did use 1/8 sheet on the the rudder post that the elevator wire was sewn to, but seem to recall it splitting in numerous places so I back the hinge assy area with 64th ply if I recall. I did make the actual rudder post assy (on the rudder) out of quite sunstantial size block due to the cut out required to enabe the correct amount movement around the elevator hinge assy. Also after the need for the horn mount there seemed little scope left for excess material removal.

hope that makes sense. Are those cowls the correct size as per plan?

Mustang Fever

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Scott:

Yes, they are the identical ones specified in the plans. 3 & 1/4" OD, stamped steel. I just now tried the link, and realized it does not take you directly to the cowls. Use sigmfg.com, and "fly on in". The main page has a column of options on the left. Pick "aircraft accessories" and under that menu pick "scale accessories", then pick "cowlings", then pick the steel ones, and you'll see the one you want is the AT-6 3&1/4 x 1&5/8, which are the exact dimensions on the plans.

Just got back from the print shop- I'll be cutting hull bulkheads today

I think I'm going to leave the fin/rudder design alone, as per your note, that room is needed inside for the elevator mechanisim.

siddus74

Thanks for the info on the cowls . . . I would like to get a couple for mine I think, wonder how much they weigh though?

Mustang Fever

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When they arrive, I'll see if I can weigh them. I think they're drawn sheet metal, which is more of a stretching than a stamping process, so they might be quite light. If they're too heavy, they would at least make good patterns for a carbon fiber layup.

Mustang Fever

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Output since the plans arrived yesterday.

Currently dealing with more snow than this area has seen since just before we moved here in 1979. Bites into the model building time.

siddus74

Those formers . . . I cut mine this time last year :-) looks good. Do you use a fret saw or similar? If I didnt have both a fret saw and pillar drill in my model room I would feel really limited.

I am glad you are going to build this plane, I cant begin to tell you how well mine flies and everyone that flies it loves it - shame your going leccy but still . . .

Awful lot of snow on your roof, wonder about all the additional weight? we dont get allot snow here in the UK, just rain.

Keep us posted with your build pictures please - helps with motivation all round I fell. My Ivan Pettigrew Martin Mars plans turned up this week. I am going to build that next - it's going to be my crowning glory.

Rgs,

Scott.

Mustang Fever

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Scott:

I have a cheap band saw (pic 1) with a very narrow blade that I use for cutting almost all my pieces. It can handle most radius's, as well as notching. When cutting out the centers, I drill a quarter inch hole and then use a scroll saw. (2) It's blade is removable so that it can be put through the hole, then re-attached. Is a fret saw English for scroll saw, or is it what we refer to as a coping saw? (Mine is laying on the scroll saw.) When I started building six years ago, all I had was the scroll saw, a razor saw (straight) and sandpaper. The bandsaw is a recent aquisition, I got it last year for about $100. Too inexpensive to pass up. I've reached the point with it where I have very little sanding to do after cutting, but when I do, the disc sander is a dream for "touching up". (Pic 3)

I can still change my mind about the power, but probably won't. One of the reasons for building this bird is to have another "winter flyer". Seaplanes fly so well off the snow, but glow engines don't do very well (or at all) at below freezing temps. Have you been able to tach your engines? My Astro 020s turn 19,000 RPM plus on the ground with 6x4 APC "E" props. I'm guessing the 10s turn a 7x4 at 15,000-16,000.

The wife and I used our roof rake for the first time yesterday. Probably pulled a ton of snow onto the ground. We'll be out there again, today. Living near the 45th parallel is so interesting some years, without the Gulf Stream to moderate things. One can't survive here without either a snow thrower or a pickup truck with a plow blade.

I know you'll start a new thread for the Mars. I can't wait. Do you plan on beefing it up a little for glow engines, or will you go electric? I did some calculations on that one, and it looks like four of the Master Airscrew 550 motors with the MA 3.5:1 gearbox and 10x7 props would work very well. Cheap- the whole thing comes to less than $300 U.S. with three 6 cell 1900 Sanyo SCR packs. Somewhat more for LiPos.

Made a bit more progress on bulkheads last night. Only the ply one remaining, then it's off to the keel pieces. Like Bud says in the article, she starts to look like something very quickly. Moving the step forward is working well, so far. The V angle on F and G gets shallower as one moves forward and their bottoms are raised to change the contour. I have a "D1" instead of an "E1" to accept the sheeting above the step. I'm probably going to use some "cheater" blocks on the bottom at the step. My Mariner has these, and they really improve the takeoffs. (Flat bottom hulls always plane easier than V hulls.)

Later.

siddus74

Bob,

You are fortunate to have the room for a fret and band saw, I have to comprise as I have a bandsaw but it has to live in the garage. I could easily fill the model room with tools not leaving me enough room for building and storing them. I would'nt mind a disc sander actually, but I get by quite well have an extensive set of permagrit sanding tools- have you heard of them? I also have a set of brass hole borers (softbore from the states they were expensive but when you need a hole theres nothing better!)

You sound like you kow your electrics, I will like some serious advice closer to the time on the mars as my understanding is lacking in this department.

Progress on the bulkheads looks good, be interested to see the side profile of the hull with your changes, with regards the addition block like your mariner I will be surprised if you'll need them but they do look neat addtitions.

Scott.

Mustang Fever

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Airplanes always expand to fill the available space, yes?

Here's a shot of the cowls. Sig was FAST. My trusty electronic powder scale says they weigh 25 grams each, under an ounce.

Mustang Fever

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I can't believe how quickly this beauty frames up!

I just went downstairs to correct an error on bulkhead B (Bud left the upper notch off the drawing, and the corresponding notch in the upper outline piece) about an hour and a half ago, and ended up getting most of the hull framed. The fit is very good ( not perfect) which says a lot for the quality of the drawings, because this is a complex structure.

A couple of notes: I put some 3/16x1/4 stock on both sides of the keel, between the formers in two places, so that I could pin it solidly to the board along the flat run from A2 to the step. As I worked my way aft gluing in formers, I used a straight edge to keep the keel true- pieces of the same stock drop down from the keel and are pinned against the straight edge.

Fun build!

siddus74

Bob,

Looking good, it does come together really quickly - does wonders for the motivation eh? Are you building it with superglue?

Scott.

Mustang Fever

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Mostly super glue (CA). The doublers I stuck on with Elmer's.

Merry Christmas

squeakalong

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Merry Christmas!

Hello Bob! When you get ready to maiden that PBY I'd sure like to be there to watch. Nice work so far (I'm driving down to Cadillac to do my building from now on at your house ..). I tried to order those same plans from RCM about a month ago, along with some others, and the site would not complete the order process. Took all the "plastic" info and then the web page "hung up". Thanks for the above info on the engine cowls, too.

Cheers,

Joe

BTW: We have LOTS of snow on the roof here in Interlochen...might just have to get up there today and try to get some more off the roof before the rain starts on Friday. []

Mustang Fever

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Joe:

Merry Christmas! Good to hear from you.

The maiden will likely be off snow, if conditions stay OK for that. Right now, I can't get to any of my winter sites because none of the lots or entrances have been plowed. Perfect flying day, too- overcast and a light west wind. If I was really hard core, I'd walk over to Baker College and use their parking lot, but that's about a quarter mile in 1-2 feet of snow. Not today. Back downstairs I go to put some more pieces on the Catalina.

Mustang Fever

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Got on another roll today and have the hull almost all framed.

Scott: tried to get a couple good closeups of how I modified the bottom contour so as to get the step on bulkhead D instead of E. Seems to have worked.

siddus74

Bob looking good, I see the step is just aft of the CG now . . . maybe a side on pic?

Scott.

Mustang Fever

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Here ya go-

I raised the bottom and flattened the angle on F just a tiny bit. A little more on E. Then, I altered the shape of the keel so that it went more or less horizontally striaight from E to D, and made a D1 that matched the shape and height of E. Instead of having the chine rail split at the step former, I just ran one piece from A1 to G. Did a lot of kerf cutting inside the various bends.

Looking at the wing design, I've dispensed with the retractable tip floats- it would require a lot of strengthening to withstand the stresses, and in any event, a retract servo won't fit inside that skinny airfoil.

I'd love to be able to fly this thing without ailerons. What's your opinion on that? Did you need them a lot to keep the wing level on TO?

siddus74

Ah, the skinny aerofoil - I remember now . . . I contemplated the aileron servo's and there installation for quite some time, in the end I used the waypoint 150MG's infact I used the same ones in the Canadair and have a couple for the Sunderland (they are great servos)

I think if we are honest we instinctively use ailerons on take off, so I cant tell you what it would be like not to use them. Even the vintage stuff I have with huge diherdral where the rudder is on the aileron channel gets used during take off.

It is possible to fly the cat on rudder only, I have flown mine only on the rudder but not in wind. I would not sacrifice the addtional control that ailerons give, having ailerons does give so much more control and gives a the ability to fly in higher winds safely. There is not enough dihedral I feel to consistantly take off fly round and land easily, and enjoyably time after time. I have flown mine in winds in access of 15mph where it is stationary in to wind, you would struggle to do that safely with rudder only.

I think if I were building mine again I would definately still have the ailerons and the washout.

Mustang Fever

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Thanks for the thoughts, Scott. I'll build it with the ailerons, then. I'm close to having a plan for doing so, using one micro servo. I'm going to use two old standard servos I have for rudder and elevator, shoved all the way up in the nose as far as they'll go, that way I'll have most of the length of the "shelf" for locating the flight pack to get the CG correct.

One very nice thing about electric motors- the APC 6x4E prop is identical in profile to the 6x4E "pusher", so counter rotating engines are possible. With a brushless, all one must do is swap two of the wires to get this, then turn the pusher prop around forward. If I'm thinking correctly, I'll want the "normal" motor on the left, and the counter rotator on the right, so the advancing blade is inboard on both sides.

I ordered the receiver, the Sullivan push cables and some 1/2 A control horns from Tower this evening.