Chevelle

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Greetings. I don't know how much interest there will be for this thread given that the kit has long been discontinued and now even the ARF is out of production but here goes anyway. We are talking about the Great Planes kit of a scaled up version of the classic Lew Andrews Aeromaster. The original is certainly a favorite sport biplane along with the Sig Hog Bipe and the Skybolt.

In the way of history, Great Planes acquired the rights to the Aeromaster and released a kit called the Super Aeromaster. This kit had some improvements (depending on your point of view) like an engine cowl and traditional means of mounting the top wing instead of using rubber bands.

I have been flying an original Lew Andrews Aeromaster for about 5 years now and it is a terrific plane. I am not a radical flier and this plane can do everything that I would ever want and more. I am sure that in more capable hands than mine, it would also prove to be a very satisfying plane.

About two years ago I bought a finished "built-from-plans" version of the the Giant Aeromaster but I was not completely satisfied with it. I think it was built unnecessarily heavy and required quite a bit of tail weight making it even heavier. (That plane is in my [link=http://uk.youtube.com/watch?v=gjQz2hFdHOQ]"Smoke Dreams"[/link] video.) It flew OK but I wanted to build my own. I eventually acquired both the Great Planes Super Aeromaster kit and their Giant Aeromaster from eBay. So let's get started....

Initial Thoughts...
Before starting the plane I gave some thought about what I wanted to do with it. Smoke was definite but I wondered what I could also add. How about a bomb drop!!! I can hear you now. "The guy complained about the weight of the last one and how he wants to add stuff like smoke and bomb dropping." A valid point but like I pointed out, the plane should be lighter even before adding the extra goodies. Also, I believe that I have devised an extremely light and versatile bomb drop method that is also dirt cheap. (More about that when the time comes.)

Getting Started...
First thing was to get the shop ready for a new project. With the benches and the wheeled work table cleared, I was ready to unpack and boy, there sure was a lot of wood to unpack. This is my first Great Planes kit and if they are all like this, I am impressed. Quality materials all around and neatly packed in bundles organized for easy retrieval. The plans are clear, well labeled, and on quality paper. The instruction book is OK, nothing impressive but it does the job. The plentiful black and white pictures are reasonably clear. The written instructions are easy to follow and not confusing but this is not a beginners kit by any means. Intermediate skills are essential. A lot of quality cuts from stick and sheet stock are required for a good fit and a quality outcome so care and patience are necessary.

The Tail Feathers...
The instructions start with the tail so that's where we shall begin. As you can see, the elevator is built up and then covered instead of just a slab. This yields a light and surprisingly strong structure and very straight. The first step is to cut and set the center section on the plans. Right off the bat I recommend a deviation from the instructions. The booklet calls for measurements to be marked on the one piece balsa center and then cut to make the correct angles for the leading edge. I feel that this is too inaccurate and recommend that you lay the piece on the plans and them mark it before cutting. It will turn out much better that way.

After the center piece is set, it is a simple matter of building the perimeter of the stabilizer. Then comes the internal pieces. Here is an example of the need for those quality cuts. Everyone has their own method but which ever you use, it is best not to just "eye ball it" and used you hobby saw to cut the internal pieces. As for me, I lay one end of the stick stock against the edge to be glued and then use my Exacto knife to make a mark at the other end at the correct angle but just a little short of the right length. Then I make a rough cut with my hobby saw leaving some wood between the mark and the cut so the piece is just a touch too long. It usually takes a trip or two to the belt sander, shaving off a little bit each time, keeping the edge parallel to the knife mark, before the piece fits snug. It may be tedious but it makes a very strong part that looks great. (Of course only I will know!)

After framing the stab, it is then sheeted and sanded to shape. The elevator is two separate pieces and are also built up but not sheeted. The trailing edge of the stab is left flat and the leading edge of the elevator sections are angle sanded to a point.

The instructions call for and show flat hinges. I prefer the rounded Robart style. When the time comes, I will drill small holes in the respective parts but for the very small Robart hinges. I use the small hinges just to hold everything together. This way I can assemble and disassemble things as needed until final assembly. Then I remove the small hinges, drill the proper sized hole and install the correct hinges.

The vertical stabilizer and the rudder are constructed in the same manner. I was very pleased as to how strong, light and straight the tail came out.

Next, the lower wing

Rodney

I just finished and now have about 15 flights on my Giant Aeromaster. I deviated a bit from the kit plans as I made the elevator a one piece unit and am using pull-pull on both elevator and rudder. I also over powered it. I have a Quadra 72cc swinging a 20-10 prop. It weighs 20.5 pounds dry and flys like a trainer. I'm using Colman camp stove fuel as the gasoline here in Florida contains 10% alcohol and that was fouling up my Walbro Carbs. After two rebuilds of the carb I switched fuels and have had no trouble since. My reason for the Giant Aeromaster was that I have had seven of the old Aeromasters and liked them so well I decided to try the big one.

Gray Beard

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I sure hope you make/made templates for all the parts. This was one of my dream kits when it was still being made. I didn't have the 200 beans to buy one though, then it went out of production. I found A kit A few years later but in the week it took me to get the money it was sold. It's still one on my wish list.

CrateCruncher

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Thanks or sharing your build Chevelle! I too am an Aeromaster fan that would like to someday build the "BIG ONE". Gray Beard makes a good point about templates. I seem to recall the .60 size plan had all the rib and bulkhead outlines on it already. Does the giant version plan have enough bulkhead/rib/cabane outlines to scratch build from the plans? Great Planes still sells plans of all their old kits and I think the canopy and cowl are still available as well.

Jacque

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Rodney, What kind of problems did you have with your carbs from the gas here in fForida. I have been using it for several months. Are my troubles yet to come? I use Zenoah engines. thanks ..........Jacque Waco Brotherhood 27

Jeff Worsham

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Chevelle- very nice build thread you have started here! Returning to R/C after 10yrs, I didn't know they did a giant Aeromaster. I'll enjoy watching your build. Nice clean shop and Great Pics!

Chevelle

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Thanks guys for the response. I guess there is enough interest to go forward with this after all. It is amazing how much interest there is in the Aeromaster after all these years.

Rodney: 72cc!! Oh my! With that kind of horse power I would think the top wing would be optional!

Gray Beard and CrateCruncher: No, the plans for the Giant do not have all the formers shown separately but it shouldn't be a big deal to fabricate formers that would do the job even if they are not exact. The ribs aren't shown separately either but like the formers, are shown not-to-scale in the assembly booklet. You can pretty much get what you need from the plans and booklet. I dunno but it seems to me that I couldn't scratch this one up for less then what the going price is on eBay. One good thing about the trend to ARFs is that eBay kit prices so not have much of a premium.

Salute!

jagnweiner

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Chevelle-

I need to re-build a lower wing from a Giant Aeromaster (ARF). The ARF wing is on backorder and I'm thinking about ordering the plans for the kit and building the wing from there. Any chance you'd be interested in either making me a 2nd set of ribs (for a fee, or course) or at least tracing the different ribs so that I could make templates and cut my own?

BTW, looks like you're off to a great start!

Rodney

Evidently the alcohol attacts the rubber or rubber like gaskets and the tiny particles clog some of the tiny apertures. As soon as I demanded full fuel flow, the engine would stall do to lack of fuel. No adjustment of the needle valves would correct the problem. I have heard that Walbro now does provide kits that have alcohol resistant gaskets and/or flapper valves but have not checked for sure.

Rodney

Here is a picture of the Giant Aeromaster with the Quadra 72CC.

Chevelle

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Here we go with the next installment.

Building the Lower Wing Halves...

The lower wing starts by building four reinforced ribs, two for each wing. It's pretty clever really. The plywood partial ribs create pockets at the curved cutouts. These pockets hold disks that when eventually glued into the pockets, become the mounting points for the interwing struts. As the manual says, care must be taken to not get epoxy into the pockets. That would make the insertion of the disks more difficult.

Next comes a pretty traditional wing buildup process. The lower wing is built in two identical but mirrored halves. A hardwood spar is secured to the plans and then the ribs are added. The rib tabs keep everything at the right angle and stable on the table. The manual suggests that you dry mount the ribs on the lower section of the spar and then add the top hardwood spar and then glue them all at one time with CA. I think that it would be tough to keep everything true. I went the more traditional way and set all the ribs in for a test fit and then glued them in one at a time using a triangle to make sure they are all perpendicular. When that all dried, I then set in the upper forward spar for a dry test fit. I removed it, laid in thick CA and then set the upper spar back in. I went in smooth and straight!

There are a lot of steps to this plane. This is not a quick build but a very well designed and strong plane will be the result if you take your time. All the best design features are here. Double hardwood fore and aft spars, plenty of shear ribs, even on the aft spar and all the ribs are capped making them I-beams, again, a strengthening feature.

The trailing edge is added as is wood for the aileron hatch and then the sheeting begins. All along the leading edge is sheeted as is the trailing edge. The center is sheeted next. The instructions imply that just two pieces of sheeting will be enough to sheet the center section. That didn't work for me on either half. There was a very thin gap that was too thin to fill with a sheeting strip but too thick to ignore. I used some scrap 1/4in balsa and scored the sheeting, removed the little bit and glued the 1/4 strip in nice and snug.

So just as you get the wing half built, the plans call for you to cut notches in the root ribs! To be honest, the instructions for marking and then cutting the ribs were confusing and so I left that for later. As it turned out, it was a good idea. Once everything has set, the wing half is to be removed and then the top side is to be sheeting and rib caps added. Since I wanted to add a bomb drop, I held off on finishing the top side. Instead I built the other half of the bottom wing stopping at the same point in the instructions.

Joining the Lower Wing Halves...

Now it was clear how and why the root ribs needed to be notched. It was to accommodate the rib joiners. (Even though I read the instructions several times before I started, this just wasn't evident to me and the picture wasn't particularly clear. Maybe it's just me.) So using the joiners as guides, I marked and cut the ribs. Call me odd but I cringed the whole time while I was cutting such important structural members!

Here is where I deviated from the instructions and highly recommend you do the same. The wings are joined with four plywood joiners. One goes along the leading edge and serves as a front bolt plate. Two more are glued to the fore spar as if they were sheer ribs and the last goes along the trailing edge. If I had sheeted both sides of both halves, I first would have had to insert and glue all the joiners into their positions in one wing half. When dry, I would then have had to slide the other wing half onto the joiners and glue it all together. The existence of the sheeting would have made clamping and getting epoxy into all the best places more difficult.

Since I did not have sheeting on the top of both wing halves, I could glue them into both halves at the same time! (Refer to the pictures below.) It was much easier to get plenty of epoxy where it was needed best. So glue was added to the the root ribs and the front bolt plate joiner and then the wings were joined together and clamped. I used a four foot metal straight edge to make sure the spars were dead straight and aligned. I added the other joiners in but without glue just to hold things in place. After the epoxy hardened, I removed the rest of the joiners, glued them up with fresh epoxy and then put them right back in.

Viola! A wing (almost)!

Next, the bomb drop and aileron wires.

do335a

Looks nice so far, Chevelle.

I'm a bit curious though.

It's great to see that when you built the tail you made absolutely certain that the truss members perfectly fit the leading and trailing edges for a strong, coprrectly built structure (that's how I build too).

In the last pic of your wing, it appears that your shear webs do not contact the sides of the ribs. Is there a reason that you left those gaps instead of filling them so that the webs would contact the ribs?

Chevelle

My Feedback: (2)

Ya know, I thought the same thing. I didn't really get those gaps. The way those shear webs go in is to place the sheet end in and the sheet isn't wide enough to cover the full span. It would have taken one full piece and another small piece to cover the whole space without a gap. I double checked the plans and sure enough, even the plan show the shear webs not covering the whole space. That wing is plenty strong enough and I am sure I will not be pulling anywhere near the number of Gs it will take to bust that wing so I left it as called out. I did think it odd though.

Bob

CrateCruncher

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Here's a piece of historical trivia about the Aeromaster. The first Andrews kits had straight wings. Then the kit was updated as the "Too" adding the option to build one or both wings swept using all the same parts as a straight wing. Naturally a tapered wing is going to have a greater web distance between the ribs than the straight wing and so the webs included were a bit too short to cover the space. Wouldn't it be kinda funny if the "Giant" designer copied it thinking it was intentional?

Chevelle

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Interesting point there Crusher. I have a "Too" that has the swept back wing. To be honest, it was so long ago since I covered it, I don't remember that deal with the shear webs on that plane. I would think that Great Planes (or whomever did the conversion for the Giant) would not have left those gaps for that reason but I suppose stranger things have happened.

Chevelle

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Bomb Drop

For me, part of the fun of building is the ability to customize each plane, not just in color scheme but with goodies like smoke and bomb dropping. I have never had the opportunity to drop anything (intentionally) from an R/C plane and this build seemed like a good opportunity to give it a try.

So here were my goals in the approach...

[ul][*] More that one independent drop
Having the ability to make more than one pass at the target would give me a better shot getting closer and make it a lot more fun.
[*] One servo
So the trick is how it have two independent drops without the added cost, complexity, and weight of two servos.
[*] Flexibility
I'd like to be able to drop different thing like bags of flour, bomb-like looking objects, or maybe even serve as the jump plane for an R/C parachute figure.
[/ul]

So with a loose set of requirements, this is what I came up with. A recessed compartment is built into each side of the bottom wing. Keeping with the flexibility idea, I decided to go with two pins holding whatever it is that I will be dropping. Guide sleeves were glued into each drop assembly. Then separate control rods were used with pins engaging the guide sleeve. The other ends of the control rods were attached to each other and then attached to a clevis to be connected to the servo arm.

A compartment in the wing for the bomb drop servo was framed up out of scrap . A one sided servo arm was used. Two holes were drilled into the arm so that both control rod clevises could be connected without interfering with each other.

I used the three position switch on my radio for control. When the switch is in the center position, the pins are positioned on both sides so that they go through the sleeves, through the objects to be dropped and then engage the opposite side of the drop assembly. When the switch is thrown in one direction, the pins on one side are retracted just enough to drop the object but on the other side, the pins engage further and therefore still keep that side from dropping. When the switch is thrown to the other direction, the pins are retracted from the side that still has an object and so it is now dropped.

Since I'm not sure what all I will be dropping, I added a block with blind nuts to the rib next to the drop assembly. This will be used to hold down a strap that will hold the object and be engaged by the drop pins. Because something may be held to the wing between the ribs, I also added some balsa sheeting between the drop assembly and the nut block. This is so what ever is being held is not being held against just the covering.

Next, the Upper Wing...

carrellh

The manuals for the kits I have built (three, working on a fourth) have all said that shear webs do not need to be glued to the ribs.

Here is a quote from page 13 of the Great Planes Corsair 40 manual:
D D 10. Install 1/16" x 3" x 1-5/8" balsa shear webs (W11) on the aft side of the spars from T-1 to the wing tip. Install one extra shear web on the forward side of the spars between ribs T-1 and T-2. Use medium CA and be sure to get a secure bond. It's not necessary for the shear webs to be glued to the ribs.

On the Corsair I did make the first shear web (between T-1 and T-2) fit the ribs so I would have a closed pocket to hold the epoxy when joining the wing panels to the center section. All of the others were just glued to the spars.

Roary m

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I have both sizes of Aeromaster kits and have bookmarked this build thread so I appreciate your taking the time to do the work here. I have built I don't know how many planes over the years, but for some reason having extra info and pics along with more sets of eyes involved in the process makes the build go over easier. There are so many tricks and techniques that you forget over time and here someone will step in and refresh my memory on stuff. Thank you for doing this thread.

catfishjohn

I just acquired a partually finished Aeromaster 60 size Great Planes kit with the fuse already finished. The die cut wing ribs are missing but the plans are there and I plan to make my own. Thanks for posting your build here so I can refer to yours since its my first time with a kit. I do have a couple of guys at work that have built many planes over the years so I wont be completely on my own. Keeps those posts coming. Thanks, John

SoCalSal

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Hi..I'm glad your doing this build. I have always liked the Aeromaster. I got my first back in the early 70's when I really got into RC from control line. I now have a ARC sitting in the box waiting to go. I found this ARC by Great Planes ( Great China PLanes) on-line and at $150 it was not even a second thought type of purchase. Now I find this build thread and it is really interesting to see your construction against the "factory" built version. I will be open here...My ARC is very well constructed.which kind of surprizes me but all joints are tight and the wood is of great quailty. Finish sanding is done and all it needs is covering and the hardware installed to take her up. But I think I'll wait till you get along in your build incase there is something you do that I would like on my AM.

Keep this thread going. there are many of use out here that really know how great a plane the Aeromaster is no matter what size .

LONG LIVE THE AEROMASTER it is just as it's name implies.......Master of the air.

Chevelle

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Whew! This cryogenic freeze thing isn't all it's cracked up to be.

Really though, all sorts of stuff jumped ahead of this project. There was the little matter of finishing the design and construction of the full scale 1910 Hudson Flier, then the 1/4 scale version, then getting the Pup back in the air, then maidening the DR1, then finishing the design and starting the construction of the 1910 AVRO Triplane. All good things.

Ok. So, where was I?

Custom Fuselage Deck

The Aeromaster is tall (deep inside) but not super wide. It's tighter in there than you'd think. (At least I thought.) The design calls for the cap in the front of the fuselage to be built up permanently. There is space under there but it would be a bear to get to. So I decided to make the cap removable. I just tacked the formers in place and added the balsa planks as called for but did not glue them to the fuse, just to each other. I made just one former for underneath because I wanted to preserve as much open space as Icould. The formers seem unnecessary anyway. The decking isn't thin sheet but 1/4 planks. It's pretty strong.

I glued in four lengths of spruce scrap and added 4-40 blind nuts to them. Idrilled matching holes in the removable cap and covered them with scrap thin ply so the screws wouldn't sink into the softer balsa. As you can see, there are other holes in the sides of the cap are reinforced with ply. These are for switches. (More on that later.) Filler was then used in the transitions.

I used the kit's former for the end that makes up the front of the cockpit. The tab fits into the slot that was supposed to be glued. The cockpit side sticks had to be angled so the cap can be removed but that wasn't a big deal. The cap goes on nice and easy and securely.

Next, sanding and filling, sanding and filling, sanding .....

barron

Enjoying your build. I built one of these about 10 years ago. I put a zenoah g-45 on her and she flew great. and like a dummy I sold her after about two years of flying her. great plane. I wish I could find another kit.

Chevelle

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Well before we get to the finishing stuff, let's go back in time to the fuselage build.

Fuselage

The build starts with the cabane mounts. A thin plywood deck with thick plywood mounting blocks for the aluminum cabanes. Not difficult to build but a challange to get your hands in the finished fuse to tighten the screws that secure the cabanes.

Definitely not your typical fuselage construction. This thing is built very strong, in the same tradition as the original Lou Andrews design. No thin sheeting over a stick skeleton. This is balsa planking with a ply inner skin all the way back. The die-cut formers fit well and the assembly is straight forward. No surprises. As you can see, the fuse was built without the front cap permanently installed. Typical turtle deck construction with long stringers giving the Aeromaster its destinctive shape.

Iliked the provided pushrod guide tubes very much. The angles were worked out very nicely for low friction smooth operation. Three are needed. One for the rudder and two for the separate elevators. Since I'm not running a separate servo for a tail wheel, Iused the extra tube for the antenna wire. (It's getting pretty lonely at 72MHz.). The tubes sanded nice and flush for a very clean exit out of the fuselage.

Next, the finishing in preparation for covering.

Tom Nied

So whatever happened to the finish?

Chevelle

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Oh my goodness. I guess I dropped the ball on completing the build thread. Well I'm happy to say that it concluded very successfully.

https://www.youtube.com/watch?v=qc7emfn_Bek