Miles M38 Messenger from Aeromodeller plans

[Bill G]

This will be my second Miles aircraft in recent times, after building an Aerovan recently from scratch. The vintage Aeromodeller plans seem to generally be good workable plans, with this one found at outerzone.uk. This plan was drawn by HJ Pridmore, and the prototype M48 was likely chosen for giant scale rubber, as it lacks the added weight and complexity of the M38's flaps. Since the M38 is the commonly known version of the plane, the build will be an M38 build with slotted flaps similar to the Aerovan. I also recently built the Aeromodeller Heston Phoenix plan by Eric Fearnley, which is an excellent off the board flyer. Both designs use a thick airfoil, which proved to have a good speed range on the Phoenix and dismissed some of my concerns about using a thick section on a model this size. I had a geared setup that was planned for use on the Phoenix, but proved to be slightly heavier than needed for the application. Lo and behold, the M38 has a very similar cowl/vent opening which the ply gearbox mount was configured for, so it may prove useful for this build. The plans were enlarged slightly beyond the 37" span to 40" thanks to Adobe, which was not intentional but acceptable. I recently got an update of the free package that would actually print all the pages, for the first time. I've never used Adobe in the past for printing plans, and will likely revert back to my prior method of scaling which is bit cumbersome but exact. On a real Miles building trend, the Aeromodeller Speed Six is another model on the list.

The parts set was cut out using a method which I've been using for quite some time with accurate results. The wood stock is placed under the plan, where the part outlines are scored over with a dull exacto knife. The scoring leaves an imprint for cutting, while not cutting through the plan. After cutting out the master part, a second part is cut using the master as a template, as most parts are required in sets of two. No cutting templates are needed, and a parts set can be cut rapidly.

Using Dubro parts, Micro Losi-T shocks, plastic and aluminum tubing and a few other bits, the landing gear assemblies with functional shocks were fabricated for the plane. It's amazing what can be fabricated, using off-the-shelf Dubro and other hardware.

My favorite so far is this red model:


This photo shows a good view of the gear struts:

[baz49exe]

Looking forward to seeing this build develop Bill. Another little modeled subject.

[pmullen503]

Nice work on the landing gear. Another multi-rudder plane! At least it only has one motor.

[BroncoSquid]

Beautiful as usual. I hate the way you make it look so easy. I will use this thread for refrence anyway.
I have been looking forward to another Bill G build.

[Bill G]

Thanks for the comments all.
Barry I am amazed that there are no kits for this plane made by one of the small laser houses, given the popularity of the plane. I was at the LHS yesterday, and lo and behold, an rc version of the red model is pictured in Flying Scale. Hopefully one copy of the issue will not sell and I will get it at a discount next month.

Bronco it usually takes me a good week of procrastinating before I finally get around to printing the plans and cutting parts. Once the basic parts kit is cut, it gets a lot easier. The "score along plan with dull knife with wood underneath" method really is easy though. That's probably what really got me started with the balsa scratch builds, as it does make it a lot easier and faster. I keep trying to "sell" the method, as I would probably not be building these planes, without speed tricks for cutting the parts sets. I lose interest quickly and therefore have to find methods for rapid building. I'm not one of those types that can spend a year on a model.

Pat I had the similar thoughts with yet another tri-rudder subject. I'll probably use a linkage setup that is similar to the setup used on the last build, as it seems to work well. Same thoughts also on getting a break with one motor. Two twins in a row was enough for a while.

[BroncoSquid]

I do something simular for making parts. I make 4 copies of plans. One to cut up for parts, one to build on, one for refrence, and one backup. I roughly cut the parts out of the plan with scissors, a quick light coat of spray glue, paste and cut. Peel and stick to make multiple parts.
After cutting 70+ parts out for the Storch, I hav'nt even started wing ribs yet, I am taking a short brake to build a laser kit. If I don't get to glue something I am going to go crazy!

I am going to download the plans just so I can follow this thread closely.
I noticed the plans don't show the intresting flaps of the real plane. I assume you are going to make them.

[pmullen503]

Originally Posted by Bill G

Pat I had the similar thoughts with yet another tri-rudder subject.

Your next build will have to be something tail-less, just to get it out of your system.

The bulbous windscreen looks tailor made for shrinking a pop bottle around a wooden form, or building a proper vacuform table.

[gramps2161]

Got to post a subscribed I always enjoy your pick for the unusual planes, and just following along.

[Bill G]

Thanks for the comments all.

Bronco the flaps are retractable on the M48, discussed in the first post. Since this was a giant scale rubber model, the flaps would add weight for rubber flight. There was only one M48 made, but it provided a legitimate reason for the designer to choose that subject for rubber power, versus the popular M38 which I chose to model. Other than non-retractable flaps, the M38 is basically the same as an M48.

With rubber plans, it's often easier to draw new tail surface plans, versus modifying the existing drawing which lacks functional control surfaces. There are generally a number of other modifications that make the design more practical for rc electric. The plan uses stringers for the wing main spar, which could be shear webbed, but would otherwise be a bit under designed for rc. This build will use a full main spar, placed in the same location as the "main spar" stringers on the plan.

Pat the pop bottle would be a good starting point for the window glass, and I also found a very close formed plastic packaging part which could be used with a slight re-molding. Already bought the balsa block the other day for sculpting the mold. This one will definitely be easier to make with using the heat pull method, versus the Aerovan's canopy.

[Bill G]

The stab is now complete with rudder linkage, which is basically a carry over from the Aerovan build. Different from the Aerovan build, this plane has a straight hingeline. The elevator flaps will use a joiner bar, versus requiring individual pushrods for each elevator flap with a "v" shaped hingeline. The straight hingeline requires a bend in the rudder pushrods, to offset the pushrod from the hingeline to meet the rudder horns. With a "v" shaped hingeline using this linkage setup, the pushrods will naturally angle away from the hingeline without requiring a bend to meet the rudder horns. The rudder pushrods are also bent slightly downward, to allow for down elevator travel without interfering with the pushrods at the rudder horns. The center rudder is operated by a bolt that is mounted on a bellcrank, where the bellcrank rotation center is aligned with the rudder hingeline. The center rudder has a section of aluminum tubing glue into the base, which slips over the bolt.

[Bill G]

Working a bit in reverse, I tend to complete the mechanical parts such as gear and tail wheel assemblies at the beginning of a build. In attempt to look "reasonably" scale, the tail wheel assembly has suspension, although there is a visible spring on this model, to simplify the construction. The lower fork assembly is bent from a single length of wire, using aluminum oval shaped tube to cover the front portion and heat formed plastic tubing to cover the lower fork portion. The main strut uses threaded collars, with flat spots ground onto the shaft to resist slippage. The upper control horn is a threaded Dubro #2-56 shaft with eyelet, which allows for a steering pushrod "s" bend link. The lower stop collar uses a threaded shaft that is intentionally bent after tightening, with a nylon eye-link threaded over it, which provides the clevis point for the lower gear assembly.

[pmullen503]

Impressive! You must have a LHS with a large hardware selection (or own stock in Dubro!)

[Bill G]

Originally Posted by pmullen503

Impressive! You must have a LHS with a large hardware selection (or own stock in Dubro!)

They have a pretty good Dubro selection. These parts are incredibly useful. I'll study a mechanism for a while, and then go to the LHS and browse through the Dubro parts. Usually several ideas come to mind, and I end up laying the parts out and deciding which ones will work best for the app. I almost used other parts for the main landing gear, and I'm glad I didn't. The heavy duty clevis is one I'll probably use again, as the part is incredibly strong and perfect for landing gear swing arm assemblies.

Started on the fuse assembly today, where the parts fit for this type of build is generally comparable to a Guillows die-cut kit, where a bit of adjusting is required. So far, only one rear fuse former required a small amount of widening, which is par for the course. A simple top view sketch can be drawn to verify the former widths, but there can still be some error in the curved portion of the fuse which is discovered when running stringers. A bit of former padding/sculpting is generally required to create a smooth fuse contour. Stringers fit the same category, where no matter how well the notches are verified on the plan, there are usually a few that require relocation. These builds are not for LC kit fans.

[pmullen503]

Originally Posted by Bill G

The heavy duty clevis is one I'll probably use again, as the part is incredibly strong and perfect for landing gear swing arm assemblies.

I'll have to get some of those and give them a try. On the subject of Dubro hardware, their heavy duty ball links are nice too. I was using steel clevises at the top of the main struts on my 50" Lockheed Vega and was busting one every third or fourth landing. I ran a thick walled Al. tube side to side, tapped the ends for 4-40 button head screws, and used the ball links; problem solved!

Another handy piece of kit are Robart pin hinges and their matching sockets. Surprisingly strong for their size. It's possible to grind off the heads of the hinge pin on a wet wheel grinder and substitute a wire clip for a low profile removable connection. Perfect for the "N" struts on biplanes or cable attachment points.

[Bill G]

Originally Posted by pmullen503

I'll have to get some of those and give them a try. On the subject of Dubro hardware, their heavy duty ball links are nice too. I was using steel clevises at the top of the main struts on my 50" Lockheed Vega and was busting one every third or fourth landing. I ran a thick walled Al. tube side to side, tapped the ends for 4-40 button head screws, and used the ball links; problem solved!

Another handy piece of kit are Robart pin hinges and their matching sockets. Surprisingly strong for their size. It's possible to grind off the heads of the hinge pin on a wet wheel grinder and substitute a wire clip for a low profile removable connection. Perfect for the "N" struts on biplanes or cable attachment points.

I like the Robart pin hinges also and always keep some on hand. Good stuff. Even picked up some of the micro Robart Pin hinges at a swap meet last weekend.

I have something now that I can actually see looking like a Miles M38 somewhere down the line. The upper rear fuse stringers are 1/16" versus the heavier 1/8" stringers used elsewhere. I anticipate this plane having more than it's share of tail weight with a sheeted stab, sprung tail wheel assembly and functional tri-rudders. Still have some stringers to install, but it's all downhill from here. There's never a dull moment in the black art of building a straight fuse using keel-and-former construction with hand cut parts from grainy vintage plans.

I gave in and ordered an outrunner, as the geared setup would have limited serviceability given the mounting arrangement, as well as limiting the forward battery placement. With modern lipos, a 3s-1000 has more than ample power for a model this size and expected weight, as well as reasonable flight time. I prefer using the battery as efficiently as possible for ballast, and using no larger than necessary. With that philosophy, my recent Aeromodeller Heston Phoenix build with functional retracts ended up at 16oz AUW with a 3s-910 lipo, and was easily hand launched and a joy to fly, landing at a relaxing low speed. I've ordered the same HURC Firepower 370 Sport motor used in that model for this build. It had considerable power to spare for the Phoenix and should still be adequate for this model given its specs, considering that this model will be a bit heavier. The motor diameter is about as large as will fit in the nose of this plane.

[Bill G]

Finished the basic wing framing, with cut-away ailerons. Cutting accurate aileron headers and notching the parts becomes a fast an easy process, after building a few. I prefer this method, versus cutting the wing formers after construction, adding aileron headers, and then having to complete the aileron construction. The hinge gap is also built in by placing spacers between the wing and aileron headers, so that the finished aileron TE aligns with the wing TE. The wing top surface will be sheeted with 1/32" balsa, and possibly the lower forward portion, cutting away the ailerons after sheeting. CF rods are used for rear partial main spars, where the formers were drilled such that the rods can be sleeved with an aluminum tubing joiner in the fuse, which will set dihedral, as well as joining the rods.

[Bill G]

The landing gear strut mounts are now in place in the wing, as well as fabricating the front canopy. One of these days I'll get around to making that vacuum machine, as the heat pulled parts are a bit testing. I managed to pull a useable canopy from a sculpted balsa mold on the second attempt. The rear portion of the canopy will be a good bit simpler, requiring only a flat sheet of clear plastic flexed around the roof framers. I also talked myself into spending the few minutes to tape the tail feathers and nose cap in place, for a bare bones photo.

[pmullen503]

Looks great. Good job on the canopy but I think if you ever get around to building a vacuform table you'll wonder why you didn't do it a long time ago.

Is this going to be a one piece model or are the wings removable?

[Bill G]

Originally Posted by pmullen503

Looks great. Good job on the canopy but I think if you ever get around to building a vacuform table you'll wonder why you didn't do it a long time ago.

Is this going to be a one piece model or are the wings removable?

At a bit over 3ft span the wings will not be removable. The original design per plan had removable outer wing panels, with the joint about 2" from the fuselage. The problem with building a vacuum machine is that the time spent detracts from building airplanes. Seriously, it is time though.

[Bill G]

Referencing a similar build without a sheeted stab, tri-rudders, and a sprung tailwheel assembly, this build will require forward mounted gear to avoid/reduce nose ballast and/or the use of a larger battery than planned. The tail servos are mounted in the forward fuse, accessible from the planned battery door in the bottom front fuse area. The rudders and tailwheel are setup with matching full throw rates, allowing for both pushrods to operate from a single E-Z link on the rudder servo.
The wing top surface and front bottom surfaces are sheeted with 1/32" balsa, adding tapered cap strips to the former bottoms to blend with the sheeted bottom surface. A second CF spar was laminated to the upper portion of the main spar, routing slightly past the LG, as well as adding mounting plates for the landing gear trailing bar rear mounting points. Without the spar reinforcement, there is a weak spot due to the spar notches, which would be a significant stress concentrated area at the point where the wing panels attach to the fuse. The wing panels have approximately two degrees of washout.
I came across a discussion of this plan at Hippocket, where it was noted that the plan locates the wing bottom slightly above the fuse bottom, which is not scale. For this build, the wing spar bottoms were notched such that the wing bottom will align flush with the fuse bottom, with the notches fitting over the lower fuse corner stringers. The lower CF spar laminations on the main spars were intentionally located a bit above the spar bottom edge, which allowed for the spar notching which properly locates the wing per scale.

[pmullen503]

Looks good, the wing should be plenty strong.

[Bill G]

Thanks Pat. A well glued ply main spar joiner should finish things up. I had originally planned to run CF hair along the top of the inner portion of the spar before sheeting but I forgot, so the flat CF sparring was used instead. I've learned to literally put scraps of tape with notes written on them across parts, so I'll remember to do those little details.

[pmullen503]

Originally Posted by Bill G

Thanks Pat. A well glued ply main spar joiner should finish things up. I had originally planned to run CF hair along the top of the inner portion of the spar before sheeting but I forgot, so the flat CF sparring was used instead. I've learned to literally put scraps of tape with notes written on them across parts, so I'll remember to do those little details.

With the D tube sheeted wing, the CF probably isn't needed past the landing gear. Then again, it's REALLY embarrassing to have a wing fold up on a scratch build. Seeing how nice the first half looks sheeted should be all the motivation you need to get to work on the other half!

Nice clean way to do the center rudder linkage, I'll have to remember that.

I forgot the install the wing hold down nuts in the formers on my He-219 and it will be a PITA to do it now. The ESC leads are also in the way so some redesign is in progress. Every time I do a multi motor or a complex single motor job I swear to myself that THIS time I'll make up the wiring harnesses and lay them out on the plans BEFORE I start building so the proper holes and access points are built in. But once again the desire to start building got the better of me.

[Bill G]

Originally Posted by pmullen503

With the D tube sheeted wing, the CF probably isn't needed past the landing gear. Then again, it's REALLY embarrassing to have a wing fold up on a scratch build. Seeing how nice the first half looks sheeted should be all the motivation you need to get to work on the other half!

Nice clean way to do the center rudder linkage, I'll have to remember that.

I forgot the install the wing hold down nuts in the formers on my He-219 and it will be a PITA to do it now. The ESC leads are also in the way so some redesign is in progress. Every time I do a multi motor or a complex single motor job I swear to myself that THIS time I'll make up the wiring harnesses and lay them out on the plans BEFORE I start building so the proper holes and access points are built in. But once again the desire to start building got the better of me.

That's always a dilemma, as the only people who don't have any afterthoughts are probably the ones who take over a year to build each model. I like to get to the building also.
The last two twins I built have harnessing and component placement that is supposed to be serviceable. Actually doing it would be another story however. I'll probably be making up a bit of harnessing for this plane, as I forgot to order a few servo extensions when I placed an order for this plane's motor. I've sworn to no more LHS servo extensions, as they are far too expensive.

I finished sheeting the second fuse half, with the bottom now remaining. As always, using Hobbico filler was just barely worth the effort to remove a few waves, as it's moisture content can create waves also. I fill any large dips with sheet balsa and then use only a thin skim of the filler. The ESC will have to be installed before sheeting the bottom, as the motor leads are protruding through the stringers. The motor could be removed and reinstalled, but it would be easier to simply connect and push the ESC through the stingers, and then sheet. I'll either pirate one from another model and replace it, or wait for once coming from a place that usually ships in 5 days to send me the ESC, although they claim to usually ship the next business day. I've been using the Dynam 18A which has a 3A switching BEC that operates 6 sub-micro servos on other models I've used it in. One of these days the other servo manufacturers will get with it, and do the same at their price.

edit: Got my ESC order faster than ever from them, in 4 days. Of course I had no idea it was coming, since there was no tracking number provided but I guess I can't complain.

[Bill G]

Now for that less than exciting covering stage, where you sometimes have to struggle for motivation. The ailerons and elevator halves have also been cut away with the hinge lines finish sanded, not shown in the photos below.