Although the Great Planes ElectroStreak ARF is a new kid on the block, its heritage is the ElectroStreak kit, a plane that for years has shown many what electric power could do when mated to the right airframe.
I have had the blessing and privilege of reviewing many fine airplanes during my tenure at the E-Zone, but few have been as special to me as this one. Although the Great Planes ElectroStreak ARF is a new kid on the block, its heritage is the ElectroStreak kit, a plane that for years has shown many what electric power could do when mated to the right airframe. A fine flyer as designed, the ElectroStreak rarely seems to remain in stock form. Like the high-performance cars of the 60's, a little extra power just seems to make it that much better, and most ElectroStreaks seem to end up with cobalt or brushless motors in the nose and up to 10 or 12 cells in the fuselage. Dave Grife used to put on a spectacular aerobatic display for 12 minutes with his ElectroStreak, which was powered by an AstroFlight cobalt 15 sport motor, 7x6 Grish propeller, and ten 1700 mAh cells.
For me, however, the allure of the ElectroStreak is not as much in its aerobatic capabilities (fine as they are), but in its sentimental value. Reviewing this new ARF version is somewhat like coming across on old high school friend that you haven't seen in years. It's more refined and sophisticated, but with the same heart and soul of the original, the ElectroStreak ARF brings back good memories of some of my earlier days in electric flight.
At a time when I was flying an ElectriCub, a good friend, Jim Dall was flying an electrified Olympic II sailplane. We started looking for something with a little more performance and a greater ability to handle the winds. Jim picked up an ElectroStreak kit and had it built in short order. Since I had more experience with R/C planes, I was selected to make the first test flight. Unknown to me at the time, Jim set the control throws to TWICE the recommended values. Needless to say, the first flight was somewhat hair-raising for someone who had flown mainly sailplanes, a Trainer 40, and an ElectriCub! Nevertheless, I was impressed by the performance of the plane, and I did manage to get it down in one piece. From there, we had a blast modifying the ElectroStreak in almost every conceivable way and trying all kinds of new things, although, always with the stock motor or a car motor and seven cells. We didn't have a lot of extra cash! After breaking the plane a few times, Jim turned over the remains to me. I rebuilt the fuselage and Jim build another wing for me, but this time it was a longer wing with an undercambered airfoil. Using a geared AstroFlight 05 cobalt motor (from my E-Cub), seven cells, and an 11x9 prop, the once again recycled E-Streak made a dandy sport sailplane. That wing broke later when Jim had it stall on him during a turn on landing. In its final incarnation, I made up a new wing based on the AstroFlight Partenavia kit, upped the cell count to nine or ten Sanyo 1700's, and used the geared AstroFlight cobalt 05 with an APC 10x10 prop. This was a truly hot performing combination, which really opened my eyes to the potential of electric flight. In this form, the E-Streak had high speed, huge amounts of vertical, and great aerobatic capability. It was an absolute blast to fly. The ultimate end finally came when one of the dowels I was using to hold the wing rubber bands broke in flight, releasing the rubber bands (and the wing!) at 200 to 300 feet in the air. I was actually able to keep it straight and nearly level for a short time, but as soon as I cut the power, it dove into the ground with disastrous results. It had a destroyed speed control, broken motor magnet, and brush housings, bent gearbox shaft, stripped servo gears, and damaged cells. It did look really awesome coming down, however!
I'm excited to renew my acquaintance with the E-Streak, and even more now that it's sleeker and more sophisticated with a new fiberglass fuselage. As an ARF, it's not only easier to build, but it's also a great value for someone transitioning into electric flight. Included in the kit are the motor, folding prop, and speed control at a cost that's not much above the price of the old kit, if you include the additional covering materials and various other components needed to finish the kit.
Kit Contents
I haven't always cared for the power packages Great Planes has suggested or supplied with their electric planes, but when it comes to kits, Great Planes really does it right, and this new ARF ElectroStreak is no exception. I honestly have to say that this is one of the finest ARF models I've come across. Opening the box revealed not only the standard ARF practices of a fiberglass fuselage, covered wings, and covered tail surfaces, but lots of little detail things that really add value to the extra price you pay for an ARF over the builder's kit. In the kit there are nice things like the plywood motor mounting plate in place, motor mounting holes pre-drilled, air scoops opened up, wing bolt holes drilled and reinforced, and with the nut plates in place, plus a number of other items. Maybe the biggest difference you'll see between this ARF and many contemporary ARF models is in the instruction manual. Most of the planes I see these days rely heavily on sketches and relatively little text. Often it takes an experienced builder to navigate his way to a properly finished airplane. It is time consuming and somewhat tedious to write detailed building instructions. Many manufacturers apparently don't want to put out the time and money required to generate a good set of instructions, but this is not so with the ElectroStreak ARF. Great Planes supplies an excellent construction manual, complete with numerous photos and building hints. While the ElectroStreak ARF is not a plane for beginners, I believe that most beginners would have little trouble completing the construction of this plane.
The kit contents of the E-Streak were nicely finished and trimmed.
The photo of the nose and tail of the E-Streak fuselage is a little fuzzy, but the plywood motor mount is already installed, and the holes are pre-drilled for the motor mount. Although the tail is hollow, a bulkhead several inches from the rear prevents this from being used as an air exit hole, as it was with the original E-Streak.
Assembly
Power System
Although the power system assembly didn't come until later in the instructions, I went ahead and assembled everything to see how it would fit together. The battery shown in the photos below wasn't included in the kit, but it is recommended by Great Planes (and supplied for the review). This seven-cell pack of Sanyo 1900's appears to be a good quality pack.
I was pleased to see Great Planes supply a folding prop. It appeared to be something along the lines of an 8x5. Although not top quality, it appeared to be a good, functional folder, and I had no problems assembling the prop or installing it on the motor. The motor is pretty much a standard issue 600-size can motor, along the lines of a Goldfire motor, and is supplied in the kit.
The speed control took me by surprise. It looks rather dated, considering the size and shape, reminding me a lot of the Airtronics MA-6 controller I had nine or so years ago. Size isn't necessarily a bad thing, however, since some of the larger controllers do a good job dissipating heat. I don't have any information on this controller, other than it shouldn't be run on more than seven cells. I suspect it may be a frame rate unit, judging by the sound of the motor when I tried it, but I'm not certain of that. At any rate, it seemed to work well, and it's a nice touch to have included in the kit, especially for someone new to electric flight.
Everything came with matching Kyosho-type connectors. I later changed the battery to Anderson Power Pole connectors, since I have all my other gear equipped with the same, but I used an adapter to join the APP connector of the battery to the Kyosho connector of the speed control.
The folding prop, motor, and speed control shown in the photos above are all included in the ElectroStreak kit. The battery is not included in the kit, but is recommended by Great Planes.
Wing
The wing was nicely finished and required relatively little to assemble. There is nothing radical here, but there are a few things you should watch as you assemble the wing. One very nice touch was the pre-slotted ailerons and wing, and the use of CA hinges. It doesn't get much easier than placing the hinges in the slots, aligning the components, and applying some thin CA.
Not mentioned in the kit instructions, but vitally important is removing the covering that overlaps the inner rib on each wing half before joining the wing halves. Failure to do so could significantly reduce the strength of the wing joint. Also, be sure to follow the directions in noting the correct orientation of the wing joiner. The top and bottom are different, but it is subtle and not easily noticed.
The servo mount was easy to assemble and install, but you may want to cut back some of the excess center rib material before installing the mount. I had to open the mount up somewhat to fit the Tower TS-10 Micro Servos, only to find that I then had to chisel out some of the wing rib to allow the servo to fit.
Tail Surfaces
Tail surfaces fit well, but here's the one place where you may want to apply more care in assembly than anywhere else in this plane. A crooked stabilizer or vertical fin will adversely affect the flight characteristics of the plane, and it's hard to fix later. Fortunately, Great Planes has some good instructions on how to check the alignment of the stabilizer by using a pin in the center of the wing and some non-elastic thread to make sure the tips of the stabilizer are equidistant from the wing. Great Planes also gives a good tip on how to remove covering over the areas to be bonded by using a soldering iron, preventing weakening of the region by knife cuts into the wood. I still used an X-acto knife, but I used a sharp blade and a lot of care to prevent damage to the stabilizer. Even small cuts can significantly affect the strength of the stabilizer and fin, so use great care here. When fitting the stabilizer and fin to the fuselage, be sure to assemble the wing to the fuselage and sight down the fuselage from the front to make certain the wing and stabilizer are parallel and that the fin is aligned with the fuselage.
As with the wing, the rudder, fin, elevator, and stabilizer are all pre-slotted and use CA hinges.
I used small clamps to hold the stabilizer in position while the epoxy dried.
Before assembling the fin, the holes for the rudder cables are drilled out, so that cable guide tubes can later be installed in the holes. I used a drafting right triangle to verify the vertical alignment of the fin. I got a little too much epoxy in the hole in the stabilizer for the fin extension, and ended up having to trim the extension a little.
Control System
Servos
Servo installation is simple. The servos are installed in a die-cut plate, and the plate is epoxied in place in the fuselage. The instructions are clear in how to orient the servos, locate the tray, etc.
Servos are installed in the servo tray before being epoxied into the fuselage. I had to relieve a little of the trays to fit the servos, but it was a pretty simple installation otherwise.
Elevator Control Rod
The elevator rod is a one-piece wire running from the servo to the elevator control horn. Stiffness in the linkage is achieved by running the rod through a plastic tube. Smaller diameter tubing is glued to the rod to act as bearing surfaces, keeping the rod linkage moving freely. This setup has the advantage of some flexibility in how it's mounted, without the length changes that seem to plague flexible plastic rods. The tube is epoxied into a bulkhead near the end of the fuselage, and then glued with CA into a plywood plate (forward pushrod tube brace) that is epoxied to the side of the fuselage near the servos. The bulkhead in the fuselage appeared to be drilled well undersize, but apparently, that was only on the rearward face. I started to drill it out with a long bit, but as soon as I cleaned up the rear face, the hole opened up and I was able to slide the tube through the bulkhead.
The left photo shows the installation of the elevator rod guide tube through the bulkhead in the aft end of the fuselage. I had to drill out the bulkhead slightly to get the tube to fit. In the center, I'm showing one of the pieces of plastic tubing that is glued with CA on to the wire to act as bearing surfaces in the tube. This makes a nice, smooth system. The photo on the right shows the rod hooked up, and the forward pushrod tube brace epoxied to the side of the fuselage. Rather than use the 90-degree bend and plastic lock supplied in the kit for the rod-to-servo mount, I used a screw-lock pushrod connector, which made adjustments much easier.
Rudder Pull-Pull Cables
The ElectroStreak uses a unique pull-pull cable system to operate the rudder, saving weight and giving very positive control. My only real comments here are that it's very helpful to have someone assist you in getting the cables tightened up at the servo arms. I had my son pull on the cable with a pair of pliers, while I held the screw-lock pushrod connector with another pair of pliers and tightened down the Allen head screw with my other hand. The result was a slop-free system. Be careful to follow the directions in drilling the rudder control horns. The hole sizes and locations are chosen to allow the screws to pass through one control horn and thread into the other. It was a little tricky getting them lined up and holding them while drilling, but the results were nice. I had to trim the elevator horn screws down almost all the way to the elevator horn nut plate to prevent interference with rudder movement.
Pull-pull rudder cable system installed
Battery, Speed Control, And Receiver
The battery tray is a die-cut piece of plywood epoxied to the sides of the fuselage. Two pairs of cutouts in the tray allow a Velcro strap to be wrapped around the battery and the tray to hold them together. I found this worked ok for preventing vertical movement, but it didn't prevent fore and aft motion of the battery. I added additional Velcro to the battery tray and to the battery to hold things much more solidly.
Great Planes recommends installing the speed control in the forward part of the fuselage (between the battery and the motor), attached to the side with Velcro. It's a little tricky trying to get a piece of Velcro glued in place with CA, to the side in an area you can't reach very well. I did it, but when it came loose, I switched over to some self-adhesive Velcro of my own. You'll also need to drill some holes and make a cutout on the side of the fuselage for the on/off switch and motor power button of the speed control.
The photo on the left shows the battery tray installed. I had to sand the sides somewhat to get the correct angle to fit the fuselage, as suggested in the instructions. In the photo on the right, I show my way of getting the Velcro for the speed control up into the forward part of the fuselage. This Velcro doesn't have the sticky backing, requiring gluing in place with CA. I found it difficult to do this, and after the Velcro strip came loose, I simply applied some of my own self-adhesive Velcro.
I found the two supplied Velcro straps insufficient to hold the battery (it could slide back and forth), so I installed some very strong Velcro on the bottom of the battery and the top of the battery tray.
Mounting the receiver behind the servos proved to be fairly simple, just requiring some dexterity to fit it around the rudder cables. Overall, everything seemed to package pretty well in the E-Streak.
The Hitec 555 receiver is installed behind the servos in the fuselage. I drilled a small hole in the side of the fuselage (through the black trim lines) to run the antenna wire.
With all equipment installed, the fit is close, but comfortable. There is still plenty of room to move the battery, which I later did when I changed power systems.
Final Touches
Great Planes did an excellent job with the motor mount holes. The motor bolted right up with no problems. According to Great Planes, the supplied motor should be broken-in by running it without a prop for 15 minutes. Adding a little oil to the bushings is a good idea as well. I followed both of these instructions, placing my battery cooling tube in front of the plane while the motor was breaking in to keep things cool. I could hear variations in the motor rpm as I started the run that later disappeared as the brushes began to seat properly. The stock motor turned the included folding prop (8x5) 11,000 rpm at 20 amps, and felt like it had reasonable thrust. As you'll see in the flying section, it could have used a little more. Before doing any flying or testing, other than motor run-in, I also cycled the battery a few times as also recommended in the instructions.
I set the CG according to Great Planes' recommendations, and placed a mark on the fuselage at that point. I later placed a little black line trim material at the spot to make it more permanent.
The finished weight came out to 46 ounces, about 6 ounces more than the original E-Streak kit built by a friend a few years ago. This was still a very reasonable weight for a 350 sq. inch wing, but I was surprised it was that much different.
The finished ElectroStreak ARF is definitely a sharp looking plane, and one that appears purposeful and fast even standing still. The last photo shows my oldest son, Patrick, holding the newly completed E-Steak before the first flight.
Flying
Stock Power System
The included power system will fly the E-Streak, but it's marginal. Our first attempt at flight resulted in an extended glide that ended with a cartwheel. My son (Patrick) gave it a solid throw, but it wasn't quite enough. The only damage was debonded glue joints on the tail surfaces, so with some quick CA work and readjustment of the rudder cables, it was ready to go again. This time I re-peaked the pack and had Patrick give it a really good heave. After going out some distance, it finally got "on step" and maintained altitude. You really have to fly it on the wing with the stock power system, since there is a very little power margin here. After a few circuits of the field (trying not to bank too sharply), I was able to get it to reasonable altitude. Here I could see the aerodynamic efficiency of the plane. Even with very little power, I could loop, roll, and fly it inverted. Every maneuver has to be carefully planned, however, since any loss of altitude takes work to recover. I always felt like the E-Streak was on the edge, and I had to be careful to keep out of trouble. Once the battery pack was down about halfway, it became more difficult to maintain altitude (much less climb), so I brought it in for a landing (and a power upgrade). I didn't expect great things from the stock system, but I thought it would have produced a little more. It's possible that with some more flying, the motor would have developed a little more power (as the brushes continued to seat). However, having flown the plane completely stock, I was ready to look at upgrades to see what the E-Streak could really do.
As you can see in these in-air photos from the first flight, it does fly well, but with the stock motor system, you definitely have to fly on the wing and carefully plan all maneuvers.
I set the control throws between the recommendations for low and high rates. These turned out to be good starting points. I later increased the aileron throw to get a little more maneuverability out of the plane.
The E-Streak isn't a slow-speed airplane, but it does have nice slow-speed manners. Stalls are mild, straight-ahead affairs, without any hint of wing drop. It will glide a fair distance on landing, but it's not unreasonable. It would benefit from differential in the aileron throws, but I didn't have a servo arm wheel available to create aileron differential. On landing, you'll have to be careful to keep the wings level at touch down, since there isn't a lot of space between the ground and the wing tips. It's easy to catch the wing on clumps of grass. You'll also discover one legacy of the E-Streak; the nose scoop loves to pick up dirt, grass, and whatever else is on the ground. If you live in snow country, it's a good idea to tape over the scoop before flying in the winter, or you'll pack the insides with snow (which will quickly melt to water).
Additional Power
After one flight on the stock motor system, I knew the E-Streak needed more power to really live up to its potential. Having a Jeti Phasor 15/4 motor and Jeti 30-3P controller on hand with nothing else to do, I opted to try out this combination in the E-Streak, saving weight and adding power. A check with some electric motor calculation software showed a 9x6 folding prop ought to pull around 30 amps on seven cells and give very respectable performance. I didn't have any 9x6 blades, but I did have a pair of 9x6.5 Aeronaut blades that mated up reasonably well with my "Turbo" spinner (with a little sanding on the lugs). This combination pulled 31 to 32 amps and turned the prop 9400 rpm with cells fresh off the charger (about 9000 rpm and 27 to 28 amps after 20 seconds), while dropping the weight of the plane to 43 ounces.
Super-charged E-Streak formula: Add a Jeti 15/4 brushless motor, Jeti 30-3P controller, Turbo Spinner, and 9x6.5 Freudenthaller folding prop. This changed netted a three-ounce reduction in weight and a huge power and performance increase.
The change really brought the E-Streak to life. Launches were no problem now. It takes right off from an easy hand launch, climbs out at a healthy angle, and has notably more speed. With this combination, the E-Streak will perform huge, sky-absorbing loops, and about any other maneuver you care to perform, short of knife-edge flight. (There is not enough fuselage area on this plane for that.) Rolls are clean and axial. I found that I had to watch the rudder, since it seems to be much more effective than I expected. A few times, I was intending to perform a stall turn, only to have the plane snap. (It does very nice snap rolls, by the way!) Overall, I would say this plane flies as I would expect a pattern plane to fly. It goes right where you point it, and it feels very controlled and competent. The only down side I noticed is that the clean shape can sometimes disappear in flight, particularly when coming head-on on an overcast day. Wind is no problem, as the 'Streak cuts through the wind easily, although the light weight does allow it to be thrown around a little bit. Flights are quite long, either on the 1900 or SR Max 2400 cells. It doesn't take much throttle to maintain flight. I know a lot of people go to ten cell power systems, but I really like this combination of high power and low wing loading. Planes seem to fly better and last longer when the wing loading is kept lower.
One of my goals in this review was to stay with a seven-cell system, since many people have seven-cell packs and chargers, and since going to higher cell counts increases the expense considerably. You can definitely obtain outstanding performance with the E-Streak on seven cells, but you'll probably have to run a more capable motor system. I think the brushless system I used is about optimum, but if you want to keep expenses down, a good low-cost alternative would probably be the Kyosho Magnetic Mayhem motor. I haven't personally used this motor, but I've heard many good things about it, and I've been very impressed with the planes I've seen powered by it. It's in the $20 range from Tower Hobbies. Another good choice would be the Model Motors/Velkom 24/10. It's a little more expensive in the $50 range, but it is a very high quality motor with very good performance. It is available from High Country Hobbies. Another step up for superb performance would be the AstroFlight cobalt 05 (available from Tower Hobbies or direct from AstroFlight), but it is more expensive at around $130. With any of these motors, you should be able to make use of the supplied speed control, keeping expenses down. You could probably use the supplied prop as well with the Magnetic Mayhem, but you would have to go to a 5 mm prop hub for the Velkom 24/10 and a 4 mm prop hub for the AstroFlight (or find a folder that fits the prop adapter).
The hopped-up E-Streak in flight looks about the same from the camera photo, but it's a completely new animal for the pilot.
Additional Modifications
Cooling
During my flight-testing of the E-Streak ARF, I found that the cooling was inadequate. The E-Streak ARF has a good scoop at the front, but no exit port. (The former E-Streak kit exited the air out the tail, but this ARF version has a bulkhead in the rear that blocks this exit.) I modified my E-Streak by cutting an air exit hole on the top of the fuselage, several inches behind the trailing edge of the wing. Air exit holes should be equal to or larger than the inlet holes (allowing for expansion of the heated air), so I tried to make the exit hole in the E-Streak ARF comparable, using the TLAR method (That Looks About Right). I chose to locate my scoop based on a combination of factors. I placed it on top, since hot air rises, and since it would be more effective than being on the bottom. I also placed it on a relatively "dead" external airflow location, keeping drag to a minimum. Finally, I tried to place it such that I would get flow over the battery and speed control, while still keeping the air path relatively clear. Blowing some air through the inlet scoop confirmed that it did indeed allow a good airflow, but I needed to substantiate the value of the scoop with flight-testing. A follow up flight did indeed demonstrate the effectiveness of the scoop. Keeping almost all of the flight at part throttle, where most of the heating occurs, I found the speed control was still quite warm, but not hot like it had been. The battery was notably cooler as well.
Insufficient cooling in stock form led me to cut a cooling air exit hole in the fuselage. I tried to place the hole in a "dead air" region that would have effective flow. I no longer had overheating problems with the speed control once I installed the hole.
Recommendations
Great Planes has done a great job in putting together a well-built, reasonably priced, superb-flying electric aerobat (other than the rather anemic stock motor). I highly recommend the ElectroStreak as an easy-building, great-flying plane that you'll want to take to the field every time you fly. If you want pattern-like performance, and you want to do it with minimal hassle, I doubt you can do much better than the ElectroStreak. I would just recommend that you change the power system if you really want it to perform.
I enjoyed your article. I've been fly for 10 years and just now thought to add electrics to my inventory. How do you calculate amp draw of motor, size the ESC, prop needed, and battery. You mentioned some software to calc. Is that shareware? Would you recomment a free web site that has a good article on this subject? Thanks a million and kind regards, Clark
Although the Great Planes ElectroStreak ARF is a new kid on the block, its heritage is the ElectroStreak kit, a plane that for years has shown many what electric power could do when mated to the right airframe.
I really enjoyed your report thank you. I have been flying R/C electric planes for a few months,
I am currently flying a Zagi Taz. I can fly a circut reasonably comfortably but beyond that my skills are a but shakey. I can do rolls and loops, asnd I,ve recently been flying quite low with reasonable success. However, the Zagi is very forgiving when I get it wrong. Can you suggest how I could guage when I would be ready?
I have just finished a Electrostreak and read your very interesting articel. I have one problem that maybe you can help me with. I have used a brushless motor wich weight 54 gr. and the supplied motor weights about 200 gr. more. I have tried to move the battery as far as possible forward, but I can not get the CG correct. Please how did you solve this problem ?? Do I have to glue in lead or do you have a better way. The saved weight is importent to keep intact I recon.
I picked up a balsa one (used) with the covering removed for $5. It will be a great winter project to put in brushless motor and have some fun with it.
Dec 26, 2002, 01:00 AM
I have just finished a Electrostreak and read your very interesting articel. I have one problem that maybe you can help me with. I have used a brushless motor wich weight 54 gr. and the supplied motor weights about 200 gr. more. I have tried to move the battery as far as possible forward, but I can not get the CG correct. Please how did you solve this problem ?? Do I have to glue in lead or do you have a better way. The saved weight is importent to keep intact I recon.
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