EPReview

	*Minnesota Area R/C Electric* Flight Enthusiasts (MARCEE)
Title: Review of Tower ARF EP Electric 2 Meter Sailplane By: Irv Cooper

NOTE: See Update with Speed 400 4:1 Gear Drive Power at bottom of article !

Reviewer Background: I was into RC Flight about 15 years ago and achieved a low-level degree of competency and was pulled away into other things. Now back I have focused on R/C Electric Flight and find it is harder to relearn than it was to learn the first time, so I wanted to 'quickly' add an electric glider to my fleet to give me some flight time in a hurry. Currently my flight skills allow me to take off and usually return safely to the earth and not be a nervous wreck when I am down.

Time to Assemble: The kit is quite complete and I felt generally of good quality. It went together fast, taking me about two evenings to get most of it done including installing the radio gear. I spent a third evening (my own doing) installing the motor and battery because I was using Koysho Truck Motors, Atomic Force R/C (an experiment) and/or a Magnetic Mayhem Monster Truck Motor instead of the supplied can motor. It took more time, as I had to solder the capacitors, wires and change motor(s) to esc connectors.

The completed sailplane was powered by a Koysho Atomic Force Motor Direct drive using the kit included 8X4 Folder Prop and 7 1700mah cells. The radio is a Futaba AM 4NBL using a separate esc. Static Thrust was approximately 20-22oz using a digital fish scale and hanging the model by the tail off of the clotheslines. Amperage was approximately 28+ amps using a 0-30 amp automotive type meter. I also checked the Magnetic Mayhem motor and the static thrust was approximately 19-21oz and the amperage was 19 amps. (Static the Magnetic Mayhem appeared to be the more efficient direct drive motor)

What I would like to have seen different:

Always topping my list, I wish the manufacturers would either not include the can motor or give you a choice of the kit with or without it.

Mostly I would have liked an option with instructions and pieces parts to make the wing a two piece assembly. I probably should have done this on my own, but remember I wanted some quick airtime.

The fuselage is too narrow to allow the battery pack to lay flat in the bottom so I had to stand it on edge and add some foam blocks to keep it from moving around. I even tried a commercial sport pack with the cells end to end and but the caps on the ends of the pack kept me from laying the battery pack on the bottom of the fuselage.

I had trouble achieving acceptable balance with the setup. Even with removing the optional belly wheel and everything moved back all the way, and using a hump pack so I could get the battery cg further back I had to add almost an ounce of weight to the tail to get close to what I 'thought' would be acceptable.

Lighter would have been better. I have not shopped similar size models, but it seems a little heavy to me for the size of the sailplane, but the model did come in at the weight listed on the box. I should note that model is quite strong, an attribute I took advantage of later.

.

The Objective Air Time:

Test Glide: The test glide was startling, actually scary, apparently I was still too heavy to the nose and it was into the ground before I could get my hands on the elevator stick. For the second test glide I pulled the trim all the way back and same results. For the 3^rd test glide I added another 1/2 ounce of tail weight and adjusted in more up trim and it glided very nicely.

First Flight Power Atomic Force: The sailplane flew well but ended in disaster. On landing approach the glider suddenly dropped a wing, nosed over and did an aggressive cartwheel removing the tail feathers. A postmortem showed that I had lost a cell on my motor/receiver battery pack and apparently lost control at the same time. Damage really was not too bad only took some epoxy and about 30 minutes. And the good news is I can take off 1/2 ox of that lead in the tail now.

Second Flight: To reduce the weight I replaced the 7 1700mah pack with a 7 500mah pack, and replaced the Atomic Force motor with a Koysho Magnetic Mayhem. This motor is longer and slightly heavier offsetting any the weight saved by the lighter batter pack. This made a notable difference, climb out was better & run time was less. I liked this combination better, but have to admit that I changed two major variables at one time and maybe the Atomic Force would have been equally as good with the lighter battery pack; however, at 30amps the 500mah pack would not last very long.

.

Future: I would like to try a geared speed 400 (i.e. 4:1). I should be able to get close to the same thrust on fewer amps. Reduce the weight, increase the run times, & improve the soaring; probably at the expense of climb out.

Conclusion: It will fit the niche I bought if for and it went together nearly as quick as I expected and I bought it on sale for $79 plus shipping. Would I purchase again? Probably, if I was looking for a low cost ARF Electric Glider. This was my first experience with an ARF and it was not quite what I expected. There was more sanding and fitting than I expected and I already commented on the weight. I was somewhat disappointed in the covering material, it was really soft, and acted more like contact paper, but I guess that is standard on low cost ARF's, I also hate to have to add weight to balance. The biggest surprise was that the recommended battery pack did not fit the way I expected.

*************************************************************************************

Update May 4, 1998

The Future is Here! The Tower EP Modified, Lightened and Flown with a Speed 400, 4:1 Gear Drive, & Cam 11X8 Folding Prop.

Nose showing Cam 11X8 Prop on a Speed 400 with 4:1 gear drive. Battery pack is 9 800AEE cells on end to move the weight as far forward as possible. I also moved the servos forward about 1" to achieve balance without adding weight to the nose. I lightened the tail by cutting large holes on both sides and on the top and bottom. Be careful on the top and bottom as there is a 1/8 sq balsa running down the center of both the top & bottom. So I cut four holes on the top & bottom leaving a strip where the balsa was.

The final weight ended up at 37 Oz ready to fly as compared to the original weight of 53 oz. Another 1.5 oz could be saved by stripping off the ARF covering and replacing with Aerospan, which I will probably do.

Final predicted flying specs by Motocalc are: 8.8 amps, 32 Watts per # input, 16.1 oz of thrust, 32.9 mph prop speed, & a 5 1/2 Minute full throttle runtime.

Actual fight performance: Climb was equal or better (probably better) and deffinetly longer than the original configuration; but, glide was spectacular as compared to the much heavier configuration.

Was it worth it, yes especially being I already had the Tower EP. But there are lighter more suitable ARF electric gliders that are made for the Speed 400 with 4:1 gear drive. However they cost about twice the Tower EP.

At any rate, my Tower EP is now fun to fly. Fun enough that I will probably recover it with Aerospan, it will look nicer and fly even better.


Nose showing Cam 11X8 Prop on a Speed 400 with 4:1 gear drive. Battery pack is 9 800AEE cells on end to move the weight as far forward as possible. I also moved the servos forward about 1" to achieve balance without adding weight to the nose.	I lightened the tail by cutting large holes on both sides and on the top and bottom. Be careful on the top and bottom as there is a 1/8 sq balsa running down the center of both the top & bottom. So I cut four holes on the top & bottom leaving a strip where the balsa was.