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The Hobby Hangar Electric Scout

Bernard Cawley takes a break from speed controls to scout out this recent offering from Hobby Hangar, a land-based plane with seaplane ancestry.

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scout01.jpg (26006 bytes)

Specifications:
  • Designed by: Scott Hartman
  • Type: Three channel high wing cabin sports model for 100-200W power systems
  • Wingspan: 48.25 inches (123 cm)
  • Wing Area: 396 square inches (25.5 sq. dm)
  • Overall Length: 32.5 inches (83 cm)
  • Weight: 40-49 ounces (1.1 – 1.4 kg) suggested, 41-43.5 ounces (1.16 – 1.23 kg) as flown
  • Wing Loading: 14.5 – 17.8 ounces/sq. foot (43 – 55 g/sq. dm) suggested, 14.9 – 15.8 ounces/sq. foot (45.5 – 48 g/sq. dm) as flown
  • Power loading as flown: about 60W/lb. (140W/kg)
  • Motor Used: Diversity Models Zoom 600 (www.flydma.com)
  • Prop Used: APC 9X4.5 thin E-prop (www.apcprop.com)
  • Flight Battery: various 7 cell NiCad packs
  • ESC used: Kontronik Sun 4000 or Schulze slim-35be, BEC used
  • Radio Components Used: Airtronics 92785 receiver, two Airtronics 94401 servos, Airtronics XL transmitter (www.airtronics.net)
  • Kitted by: Hobby Hangar, 7715 Industrial Way, Melbourne FL 32904 (www.hobbyhangar.com) phone 321-727-8227

 

 

Are you looking for a sporty-performing little cabin plane for that unused Speed 600 (or other 100-200W motor)? Do you have some 7 cell packs lying around unused since you escaped the 7-Cell Trap™, but you can’t stand to see them gathering dust? Or, do you have fond memories of your PuddleMaster and want a landplane that has similar surprising performance? Well, if you can say "yes" to at least one of these questions, then the Hobby Hangar Electric Scout might need to be added to your building queue.

 

Scout Origins

The Electric Scout comes from the drawing board of Scott Hartman. That’s the same drawing board which gave us the Ace PuddleMaster, now known again by its original name, the Pondside, (published in the March 1992 of Model Builder). To come up with the Scout, Scott took the wing from the Pondside, put it on top of a pert sheet balsa cabin fuselage, and added a simple built-up rectangular horizontal tail and a sheet balsa vertical fin. From Bob Kopski’s ReVolt! design (published in the November 1994 issue of Model Aviation), Scott borrowed the incidence and thrust angles, some structural concepts, and the strap-and-balsa-triangle-on-a-ply-plate means of mounting a motor. Then he included a simple tail-dragger landing gear, a battery access opening on the bottom of the fuselage that doesn’t have a hatch or even need one. Result: Electric Scout.

I first learned of the Scout from Scott in 1995, when, knowing that I like little cabin planes, he sent me a copy of his hand-drawn plans.  Then, in the February 1996 issue of the late Model Builder magazine, Scott’s construction article for the Scout was published. In the article Scott acknowledged the ReVolt! and another precursor, Mitch Poling’s Seagull, a slightly smaller high wing cabin floatplane, from which the basic airfoil and wing layout was borrowed (first for the Pondside and then for the Scout). So, putting a Scout on floats – especially a pair of Seagull floats as I am planning to do – will bring the design full circle.

Last fall, both the Pondside and the Electric Scout were slightly redesigned and released as laser-cut kits by Hobby Hangar of Melbourne, Florida. When I heard about this, I approached both Hobby Hangar and our esteemed editor about doing a review of the Pondside, as I had done the review of the PuddleMaster in Model Airplane News (November 1993) and I thought it would be interesting to do another. But apparently Dereck Woodward got wind of this ahead of me, and by the time I asked, Steve said the Pondside was already spoken for. (See Dereck Woodward’s review of the Pondside in the April, 2000 issue of the E Zone http://www.ezonemag.com/articles/2000/apr/pondside/pondside.htm) It only took me a moment to ask for the Scout instead. I still wanted that little sporty cabin plane that I’d never gotten around to building before, though I would periodically pull out the plans and think about it. Now that it was available as a kit, I didn’t have any excuses any more. And, I thought it might make a good plane to keep in my little pickup for spur-of-the-moment flying in a wider range of conditions than a Speed 400 type plane.

As it turns out, that’s just what the Scout is: a sporty-handling cabin plane that gets a surprising amount of performance out of 150 or so watts. It’s a little smaller and lighter than similarly powered "trainer" types like the Goldberg Mirage 550 or Great Planes PT-Electric, and a lot more maneuverable. However, the fuselage is rather lightly built, especially at the tail end, such that catching a stabilizer tip can do some damage (don’t ask me how I know this). Consequently I wouldn’t recommend it as a primary trainer. But then, that's not what it is supposed to be.

One of Scott Hartman’s original design objectives was to create a small electric sport plane that would easily handle "standard" sized radio gear. Consequently the fuselage is quite roomy, and the structure overall is light. Hauling a pair of full sized servos and a full sized receiver is less necessary today than it was 5 years ago because lightweight radio gear, especially servos, are inexpensive and widely available. Also, electronic speed controls are quite a bit smaller and lighter for a given power handling capability now than they were then. So, as you can see in the picture, there’s lots of empty space in the fuselage, even with a full sized receiver as I’ve used.

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Inside the roomy cabin of the Scout. Equipment shown is a Schulze slim-35be speed control, a full sized Airtronics receiver and two Airtronics 94401 mini servos. The motor battery goes under the ply radio tray through an opening in the bottom of the fuselage.

 

What's In The Box

The airplane, as you have probably guessed by now, is all wood, and of simple traditional construction. All shaped parts are laser cut. They are cut from various thicknesses and grades of balsa except for the dihedral braces, front cabin former, battery/servo tray, landing gear, and motor mount plates which are cut from 1/8 inch (3.5 mm) "lite-ply". There is also some 1/16 inch (2mm) sheet balsa supplied for the top and bottom fuselage and wing center section sheeting, and 1/8 inch X 1/4 inch (3.5 mm X 7mm) spruce wing spar stock, and a piece of piano wire used in making up the pushrods. The landing gear legs and tail skid are pre-bent wire (more on that a bit later). Also supplied are some CA-type hinges (these appear to be the Sonic-Tronics variety), and other hardware bits for the controls and for mounting the landing gear and the motor.

Building guidance is provided by a rolled full sized CAD plan and a few pages of instructions, which include a miniature layout of all the laser cut sheets for reference and a list of included and needed parts.

The instructions aren’t quite the thick books we see in kits from the major manufacturers these days, and there are a few confusing spots. It took me a little while to get used to the layout of the pages, for one thing. They’re laid out in two columns with a mixture of text and pictures, but rather than having a picture and a clearly associated description or step above or below it, then the next step below in the same column, the text and pictures alternate back and forth across the page. There are a few little grammatical errors (you’d think I was an English teacher rather than an engineer because I notice such things, I suppose) and a couple of places where the sequencing is questionable, as well as a couple of duplicated steps. I’ll mention the ones that gave me the most trouble or confusion as I go along.

The plan is generally OK, though there are a few inaccuracies on it as well. Most notably, the top view showing straight tapers from the main cabin to the nose and to the tail, rather than the curves the sides will actually take (unless you crack them at the cabin bulkheads).

To complete the airframe you will need two-inch or larger main wheels and a way to retain them on a 3/32 inch (2.7 mm) wire gear, covering, and adhesives. Of course a radio system (minimum of three channels with two servos) and the power system (motor, battery, speed control and a suitable prop) are also necessary. If you want a tail wheel, either fixed or steerable, rather than a fixed skid, you’ll need to supply that too.

Design Changes

In rendering the Scout in kit form, Hobby Hangar made a few changes to Scott’s original design. All the flying surfaces – the wing and tail section – are essentially unchanged and go together very easily thanks to laser cut parts. Even the shear webs for the wing spars are laser cut for you.

In the fuselage there were a couple of changes, with mixed results. Scott’s original, like Bob Kopski’s ReVolt!, has a nose that is as wide at the front as at the main cabin area. While this makes the nose very roomy, it’s also draggy, and not all that pretty, in my opinion. The kit version tapers the nose noticeably, while still retaining enough room up front to mount a Speed 600 type motor. Not having flown an original, I can’t say if the drag reduction is noticeable, but it looks nicer to me.

The other change is more problematical. Scott’s original had a 3/32 inch balsa sub-floor under which the battery is mounted and on which the receiver rests. In the kit this is replaced with a lite-ply tray, tabbed into the bulkheads at the front and back of the cabin. The servos are mounted through a hole at the rear of this tray. While this interlocking unit serves to help assure a straight fuselage, it is necessary to rework the forward former to allow the motor battery to pass through it for balance.

sct_f2.jpg (12935 bytes)
Front cabin former, with a sub-C cell resting on the lower opening. This hole needs to be enlarged to allow the battery pack to pass through in order for the airplane to balance, unless you use very light servos and a heavy motor.

Worse, most of the weight of the battery (attached to the underside of this tray by VelcroŽ) is hanging, along with the servos, from a thin balsa strip in the middle of the aft cabin former. On the first heavy landing, this will break, and the servos and motor battery will come loose. I would recommend simply not removing the plug from the lower hole in that former, but instead gluing it in place. I wound up reinforcing it with a strip of 1/8 X 1/4 inch balsa after it broke, This strip is visible behind the servos in the picture of the interior, above.

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Rear cabin former, showing the lightening hole which should be left closed and the plug glued in so that the servo/battery tray, which tabs into the rectangular slots, does not break loose on a heavy landing.

Also, this tray does not go all the way out to the fuselage sides (where it would have rested on the 1/8 inch square balsa strips there). It is fairly flexible and when you pull positive Gs, as in a loop, the tray will flex, moving both the elevator and rudder servos, and hence the control surfaces. I have braced the tray just forward of the servo cutout so that it can’t flex downward anymore and this has improved the aerobatics of the airplane noticeably.

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View through the battery opening, showing a brace I added to keep the servo/battery tray from flexing and causing the servos and control surfaces to move in positive G maneuvers.

 

Hints and Tips While Building

That said, the kit really is pretty good. Having built the all laser-cut Sig LT-25, which goes together so well that you can assemble it and then add glue, I had pretty high expectations going into this one. In general, I was not disappointed. The laser cutting is generally clean and all that is needed to free the parts from the sheets is trimming little short gaps in the cut lines. There were a couple of places where the cutting was not all the way through the wood, but nothing that couldn’t be dealt with by using a good sharp knife a bit. As in the LT-25, the wood selection was generally appropriate for the application and I only felt compelled to replace one of the 1/8 inch square sticks supplied, as it was very soft and quite a bit undersized.

I’m not going to rehash the instructions, but I will point out a few things I learned as I went along. The first component to be built is the fuselage. The sides are each formed out of two pieces of 1/16 inch (2 mm) balsa wood, interlocked together. In my particular kit the density of the two sides didn’t match very well, but the fuselage came out OK anyway. To the bare sides are added nose doublers of 1/64 inch (0.5 mm) plywood and on top of those triplers of 1/16 inch balsa. These triplers should be aligned with the periphery of the fuselage sides, and there will be a 1/8 inch gap between the upper and lower ones at the nose. This forms a slot into which the motor mount plate will go. This is a change to the kit and is mentioned on a supplement sheet to the instructions. When you install the motor mount plate in this slot and pull the nose together it will be narrower than the laminated balsa nose piece or the little strip of 1/16 inch plywood that goes on the top of the nose. A little work with a sanding block takes care of that, though.

Other fuselage construction comments and notes:

  • I would suggest marking and installing the 1/8 inch square balsa uprights on the insides of the fuselage sides before joining them to the former/battery tray assembly rather than four steps afterward (step 15).
  • I’d recommend NOT using the plan top view to cut the 1/8 inch square crossbraces, but rather size them to fit after pulling the tail end of the fuselage together. I think the fuselage in the pictures in the instructions was done as the instructions call for, and the shape of the aft fuselage is rather odd.
  • Because of the change in the kit to slot in the motor mount plate, you don’t need step 23.
  • Step 27 is a duplicate of step 18.
  • You should plan and lay out your pushrod installation and cut the pushrod exits before completely sheeting the bottom of the fuselage. The instructions omit this point and then when you get to the final assembly step about installing the pushrods it assumes you have already cut the exits.
  • I made my nose hatch rather larger than the instructions suggest (step 29), making it include upper nose sheeting and half of the "windshield". While this makes getting the motor in and out very easy, I don’t think it’s really necessary.

The main landing gear, made with the supplied 3/32 inch main leg and 1/16 inch drag brace, is a little flimsy for a 2.5 to 3 lb. (1.1 to 1.4 kg) plane. I would suggest replacing the 1/16 inch brace with a similar part made of 3/32 music wire. It will also then fit in the supplied landing gear attachment clips without needing to be built up with tape or heat shrink tubing. I built the gear from the supplied parts and bent the drag brace several times before I made up a new gear of all 3/32 inch wire.

If you’re going to operate off of a grass runway I would also suggest angling it a bit so that the main wheels are about 1/2 inch further forward than shown on the plans or you’ll be nosing over a lot and breaking props this way. I speak from experience here. I’ve also fitted #8 Trexler airwheels in order to make it easier for the Scout to take off from the thick grass at my club’s field. This gives it a bit of a "bush plane" look.

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"Bush plane" mode with #8 Trexler wheels for easier operation from grass runways.

There is no tail wheel, but a pre-bent fixed wire skid. Unfortunately, nothing supports the leg of the skid which projects into the fuselage, and after just a few flights I found it to have twisted to one side. I wedged some balsa into the fuselage on either side to support it temporarily, but the final fix was to replace it with a steerable tailwheel. If you want to use the fixed skid, I’d suggest providing a support for the upturned end of it inside the fuselage before closing the bottom sheeting up.

The tail section, which comes next in the instructions, is very straightforward. It is a simple built up horizontal stabilizer, made primarily of 3/16 inch (5mm) square balsa sticks, with sheet balsa elevators joined with a bit of 3/16 inch dowel. The vertical tail is all made from 3/32 inch (2.7 mm) balsa. The only changes I would suggest here are to hinge the rudder with tape rather than trying to slot that thin sheet balsa for the CA type hinges which are supplied, and to reinforce the fin/stabilizer joint with some triangle stock, just as Dereck Woodward suggested in his Pondside review. I did so as part of a modification to make the tail section removable.

The wing goes together well and just as the instructions call for. Only a couple of things to note:

  • The supplement sheet suggests installing the shear webs between the aft spar caps after both the upper and lower caps are installed in the ribs. This will make sure that the rear spar doesn’t sit proud of the upper surface of the wing. However, the rear spar in my airplane does project above the upper surface a bit, and it doesn’t seem to matter.
  • Step 12 of the wing instructions is a duplicate of step 2.

You can get a good idea of the wing construction, including some pictures, from Dereck Woodward’s Pondside review, as both airplanes use the same wing.

Equipment installations go just about as suggested on the plan. The cutout in the battery/servo tray for the servos is large enough for some full sized servos. I made some supplemental rails from some scrap plywood to suit the Airtronics 94401 servos I used. The receiver attaches to the top of this tray on a bit of VelcroŽ. I wound up building up a spot on the right side of the fuselage just inside the cabin to which I could attach a speed control so that the battery leads could reach down to the battery compartment. I also had to cut a notch out of the battery tray to allow the Powerpole connectors to pass down beside the tray.

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Final speed control installation on a 3/16 inch balsa spacer on right fuselage side. It needed to be in the main cabin in order for the battery leads to reach the connector on the battery below. The leads go down to the battery compartment beside the tray. Schulze slim-35be ESC shown.

At first I was leery of the single brass strip strap holding the motor in place, but so far it has proven quite adequate. It might be necessary to do something different if you were to use a motor that was physically much smaller than the suggested Speed 600/Mabuchi 550 type, such as one of the little Velkom cobalts, or an Aveox 1005 series motor. At the very least the strap would have to be further forward which would get tight on the left side, as the motor is angled to provide right thrust. You might also have to shim under the motor to get the shaft in the middle of the opening in the front of the cowl. I’ve test-fit an Aveox 1010 series motor, and it needs about a 3/32 inch shim under it to center the shaft in the cowl opening.

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Aveox 1010 motor trial fit in the nose of the Scout.

 

Finishing It Up

Mine is covered in Pearly White and Translucent Red Coverite Micafilm in the same basic color scheme as the one in the box-lid picture. This is my third Micafilm job using Solarfilm’s Balsaloc as the adhesive instead of Coverite’s Balsarite. For some reason this time it seemed more difficult, and I particularly had problems with the Micafilm creeping on the wingtips, so I have some wrinkles in the tips that will always be there. My AMA number and the word "Scout" on the wing came from Greg Judy’s Vinyl Graphics By Greg (www.vinylgraphicsbygreg.com). I also put a red stripe down the length of the fuselage with some Coverite Presto, and made some dummy windows from a gold Monokote trim sheet. It is amazing how these small touches liven up the look of the airplane.

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Two views of the just-completed Electric Scout taken right before the first flight.

For guidance I used a full-sized Airtronics receiver and two Airtronics 94401 mini servos (these weigh about one ounce each). Radio power is provided by the BEC function of the speed control. The control I’ve used the most in the airplane is the Kontronik Sun 4000, although the Scout has a few flights with the Schulze slim-35be as well.

One thing missing from the instructions is suggested control throws. Fortunately, I had that information from Scott on his hand-drawn plans. His suggested rudder throw is 3/4 to 1 inch each way, and 1/4 to 3/8 of an inch each way on the elevators. I have mine set up at the upper portion of these ranges and it is very responsive, especially on the rudder.

Also, the balance point is not shown on the plans (but is mentioned at the end of the instructions) as being right on the spar. In order for mine to balance at this point I had to have the motor battery project through the forward cabin bulkhead about 1/2 of a cell diameter. Perhaps a Scout without my removable- tail modification and with a similarly heavy motor would not need the motor battery to have to project through the hole in the former. If you used a lighter motor such as an Astro 035 or a small brushless it certainly would be necessary for the battery to have to go forward through that hole.

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Inside the nose, showing the motor battery passing through the enlarged hole in the forward cabin former for balance.

My airplane came in at just over 41 ounces (1160 g) with a 7 cell 1400SCR pack on board, which is several ounces lighter than Scott Hartman’s prototype of 5 years ago. (But add two ounces (57 g) for a 7-pack of RC2400s.) With a lighter motor it could easily be three ounces lighter still, getting the wing loading down under 14 ounces per square foot.

Another one of Scott’s design objectives was to get respectable performance from an inexpensive power system and here the airplane really delivers. I think any power system that makes good use of 6 to 8 sub-C sized cells will fly the airplane just fine – say anything upwards of 120W at full throttle. The box lid calls for a 550 or Speed 600 type motor, which is an inexpensive choice. A Great Planes Goldfire, which is a 19 turn 550 type motor, is shown in the construction photos in the instructions.

My Scout is powered by a Diversity Models Zoom 600, which is very similar in performance to an 8.4V Speed 600. This motor has a little cooling fan in the back so it will last longer at 25A power levels.

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My Scout on a low flyby at a small flying site. Photo by Scot Kruize.

 

Flying the Electric Scout

I am using an assortment of 7 cells packs, primarily some old 1400SCR packs that have been gathering dust for some time (some of them are 9 years old!), although I have one pack of matched RC2400 cells from B&T R/C, too. After some experimenting, I found the propeller that suits this combination the best is clearly the new APC 9 X 4.5 inch thin electric prop. At full throttle on the 1400’s this combination draws 24 Amps (for about 165 watts input), but the airplane will cruise on just a fraction of that – roughly 30 watts. At full bore there’s plenty of thrust for big loops, and consecutive rudder rolls (to the right) are surprisingly easy and can be nearly axial with the right timing on the elevator. For some reason rudder rolls to the left are much more difficult, but snaps to the left are quick. I’ve not been able to keep it inverted for any length of time – is has too strong a tendency to roll back to upright. There is enough power and elevator authority to do it, though.

Logged flight times on these 1400SCR packs are ranging from five to over 10 minutes. So, I should easily be able to get 15 with the RC2400s or some 3000 NiMH cells. My first, and so far only, flight on the RC2400s was a bit over 12 minutes of mixed aerobatics, cruising, and some touch and goes.

Stalls are straight ahead and are almost a non-event. With the specified elevator throw it is possible to go to altitude, pull back on the power, ease in full up elevator and the airplane will descend bobbing its nose up and down, but never breaking sharply into a stall.

However, if you are planning on using the Scout as a trainer, I would recommend reducing the rudder throw quite a bit. With the suggested throws it is quite responsive. Also, it is not so stable in roll that it will always return to level flight from a banked turn when you release the stick. Past a certain bank angle it will steepen the turn if left alone, not level off. This, coupled with the fairly light fuselage structure I mentioned before suggests that this is not the best choice for one’s first airplane. But a primary trainer is not what Scott had in mind, but rather a sporty flyer.

There also seems to be some inertia in roll that took me a little time to get used to – almost like a three channel sailplane. The wing isn’t all that heavy, so I don’t really know why it is like this, but it feels that way to me.

One of the things that surprised me was how little power it takes to keep the Scout in the air in a slow cruise. On a calm evening I have flown low and slow with the throttle stick below 1/3 while using the Kontronik Sun 4000 speed control. I once measured the static power input at this throttle stick setting and got only 30 Watts. With the big fat Trexler wheels I have on the airplane now it takes a bit more power to just cruise, but still I could get some rather long flights of just cruising around if I wanted to. However, I’m afraid I have to do loops and rolls and shoot touch and go landings, too. It will do all of these pretty well. I’m still working on my timing to get a decent looking Cuban Eight out of it, but I think the airplane can do it.

What Next?

So far I have about three dozen logged flights on the Scout, and I have several things I’d like to try with it in the future. I’ve already mentioned fitting it with a pair of floats as designed for its ancestor, Mitch Poling’s Seagull. I also will probably try night-flying with it after setting it up with something from RC-Neon or Glowire. Also, I think it may have enough lifting capacity to carry a small Advanced Photo System camera I recently got on closeout at Target, as the camera weighs just under 5 ounces. And, of course, it will have to serve as a speed control testbed for 30A or so rated controls for my "A Controlling Interest" column beyond the two that have already flown in it.

Consequently, I think it’s going to see quite a bit more flying.

So, if you’re looking for a 120+ Watt sport cabin plane, and you want to build a simple traditional wood kit, I’d suggest you give the Hobby Hangar Electric Scout serious consideration. All of the little problems I’ve mentioned are easily dealt with, and at $41.99 US it is a good value. Check it out.

 

E-mail Contact

ABCawley(at)peoplepc.com

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