E-flite Apprentice STOL: What It Is and Which Apprentice to Buy

Disclosure: Some links in this article are affiliate links. We may earn a commission on qualifying purchases at no extra cost to you.

Type "E-flite Apprentice STOL" into a search box and you get a small identity crisis. This guide checked Horizon Hobby's catalog and found no product with that exact name. What it did find is two Apprentice trainers wearing different brand badges: the small HobbyZone Apprentice STOL S 700mm and the larger E-flite Apprentice STS 1.5m. Searchers usually want one of them and are typing a mashup.

A word on method. Everything here comes from the manufacturer's product pages and instruction manuals, plus the FAA's registration rules. This guide is not based on our own flying, so you will not find stopwatch results or crash stories. Where a number is a maker recommendation, it is labelled that way.

Sorting out the names

Horizon Hobby sells under several brand names, which is how an "E-flite Apprentice STOL" ends up in people's heads. Here is the map, based on Horizon's own listings.

The status column is read from the availability data on each Horizon page, not from the generic "no longer available" text Horizon uses on some pages. Back-ordered is not the same as discontinued, so the planes may return. Stock moves quickly, so check before you plan a weekend around one.

The Apprentice S 15e deserves a footnote. It was the earlier 1.5 meter E-flite trainer, and a Horizon motor mount listing is titled for both the S 15e and the STS 1.5m, which fits the family tree. This guide found no complete S 15e aircraft in Horizon's current search, so it does not treat it as a current choice.

HobbyZone Apprentice STOL S 700mm at a glance

Horizon describes it as an ultra-micro trainer scaled down from the larger Apprentice models, aimed at first-time pilots who want to fly in more places and smaller spaces. The figures below are from the instruction manual (document 160202.3, updated 12/23) unless noted.

Two points on the table. The manual states that no additional payload is allowed and that the weight with the recommended battery is the maximum takeoff mass. And "4-channel" means ailerons, elevator, rudder and throttle, so there are no flaps despite the STOL name. If you were hoping for flaps, this is not the plane.

What is in the box

For the BNF, Horizon lists what you must bring: a 6+ channel Spektrum DSMX or SLT compatible transmitter, a 2S 300 mAh LiPo with a 3-pin JST-PH connector, and a compatible charger. That is why the BNF only makes sense if you already own Spektrum gear, and the ARF vs RTF vs PNP guide explains the trade-off between those acronyms in more detail.

The manual adds a catch for BNF owners: binding to an SLT transmitter other than the Spektrum SLT6LP will not give full functionality, and DSMX radios need the SAFE switches assigned in the setup pages. The manual lists dual-rate and expo recommendations for DX, NX and iX radios, with the low rate at 70 percent and a warning not to lower rates below 50 percent so AS3X keeps working.

Where to look for one:

• HobbyZone Apprentice STOL S 700mm RTF on Amazon
• HobbyZone Apprentice STOL S 700mm BNF Basic on Amazon

The first link goes to a verified listing for the RTF. The BNF link is a search because the individual listing showed as unavailable when checked.

How SAFE works on a plane this small

The STOL S carries Horizon's SAFE system, which has three flight modes selected by a switch on the transmitter (Channel 5), plus a Panic Recovery button.

• Beginner: pitch and roll angles are limited, the plane self-levels when you release the sticks, takeoff and landing are stability assisted, and climb and descent follow the throttle.
• Intermediate: more pitch and roll authority, self-leveling is off, and only extreme attitudes are blocked.
• Experienced: natural AS3X flight with no limit on pitch and roll angles beyond what the airframe allows.
• Panic Recovery: hold the button, return the sticks to neutral, and the system rolls the wings level and pulls out of a dive.

Some details worth knowing from the manual:

1. SAFE and AS3X are not active until you advance the throttle past 25 percent. After that, control surfaces may move on their own, which the manual says is normal.
2. SAFE is described as flight assistance, not an autopilot. Wind and environment affect it, and low altitude or slow speed mistakes can still crash the plane.
3. Do the control direction test in Experienced mode, not in Beginner or Intermediate.
4. Strong oscillation can occur at full throttle in level flight or in long high-speed dives. The manual says to reduce throttle immediately.
5. After a hard session of continuous high-G maneuvers in Experienced mode, the manual advises landing in Experienced mode and power cycling the receiver.

The manual also recommends the RealFlight Trainer Edition simulator before real flights, and the RTF transmitter connects to a PC with a USB-C cable. Our simulator guide covers how to get the most out of that before you pick a field.

What the manual says about flying it

Numbers a beginner should know before charging the first battery, all from the manual:

• Flight timer: "6-8 minutes using the recommended 2S 300mAh battery pack."
• Wind: a good flying day is calm, "less than 5-7 mph (8-11km/h)." Wind near the ground can be lighter than the wind at flying altitude.
• Field size: at least 1300 feet (400 m) of clear space in all directions, with no trees, buildings, cars or power lines. That sounds like a lot for a 700 mm plane, and the manual is blunt that the aircraft covers ground quickly.
• Launch: ground launch in Beginner mode from smooth asphalt or concrete, nose into the wind, throttle to full while gently pulling back on the elevator. For a hand launch, the manual says to get a helper if you can, grip behind the landing gear, and throw slightly nose up into the wind.
• Climb and cruise: climb to about 50 feet (15 m) before the first turn, then up to about 200 feet (60 m) and reduce throttle to around 50 percent.
• Landing: reduce to around 50 percent throttle, fly downwind past the runway end, turn into the wind, aim to be around 10 feet (3 m) as you cross the threshold, then flare.
• Center of gravity: support the plane on your fingertips 35-40 mm back from the leading edge at the wing root. Move the battery forward if the nose rises and back if the nose drops.

The manual's wind figure differs from the "5 mph" ceiling many listings repeat. The 5-7 mph range is the maker's, and it is a ceiling for beginners, not a goal. Our wind flying guide is useful reading if your local field is rarely calm.

Low battery behavior

The ESC has low voltage cutoff. Per the manual, when it engages, the plane slows and the motor begins to pulse. Land immediately when you notice the power drop. The manual notes repeated flying to LVC damages the battery, and the ESC keeps power to the receiver and servos so you can glide in.

A separate setting often gets confused with that cutoff. On compatible Spektrum telemetry transmitters, the manual shows a Smart ESC low voltage alarm that you set to 3.4V per cell, with 12 motor poles. That is an alarm threshold you enter on the transmitter, not the ESC's own cutoff.

For battery sizing and care, the LiPo battery guide covers the fundamentals, and the manual adds its own storage rules: remove the battery from the aircraft after use, store at about half capacity, and keep cells above 3V.

Failsafe

The manual says the receiver stores the throttle position at the time of binding as its failsafe. If the link is lost, throttle goes to low and the other channels put the plane in a slowly descending circle. The binding procedure matters, so bind with the throttle stick at the lowest position. Our failsafe setup guide explains how to test it safely.

Care, repairs and spares

The airframe is EPO foam. The manual says foam repairs can be done with virtually any adhesive, naming hot glue, regular CA and epoxy. That is the maker's statement, so follow it for this EPO airframe. The manual also warns against threadlock where screws enter plastic parts, and against leaving the plane in a hot car, which can damage the foam.

The manual's replacement parts list also names a fuselage with tail (HBZ6102) and the motor (SPMXAM2900). These are the part numbers worth writing down:

The propeller is the part that suffers in any foam trainer, so buy spares with the plane. The manual also covers trim: if you need more than 4 clicks of transmitter trim on a channel, return the trim to zero and adjust the linkage mechanically, since heavy trim interferes with AS3X.

Common problems, in the manual's own troubleshooting table:

• Oscillation: reduce airspeed, replace a damaged or imbalanced propeller, tighten loose controls and fasteners, check that the receiver is secure.
• Motor pulses and loses power: soft LVC engaging, cold weather, an old or damaged battery, or a battery C rating that is too low.
• Controls do not move after power-up: the aircraft was moving during SAFE initialization. Keep it still and power cycle.
• No throttle response but other controls work: throttle not at its lowest setting, throttle trim too high, a reversed throttle channel, or a disconnected motor.

The four servos are small linear units (SPMSA203 in the parts list). For servo basics before you swap any, see our servo guide.

E-flite Apprentice STS 1.5m: the larger Apprentice

The STS 1.5m is a different kind of plane. Horizon calls it the "Official Trainer of the Academy of Model Aeronautics (AMA) and many clubs worldwide", which is a maker claim rather than something we verified with the AMA. The numbers below are from its manual and product page.

The STS RTF does not include a battery or charger. Horizon says it needs a 3S 3200-4000 mAh LiPo with an EC3 or IC3 connector and a compatible charger, and it points to a Spektrum Powerstage bundle as one option. The BNF needs a full-range 6+ channel Spektrum DSMX/DSM2 compatible transmitter as well.

Both STS versions were back-ordered at Horizon when this was checked, so look at current listings before you decide: E-flite Apprentice STS 1.5m on Amazon.

SAFE Plus on the STS

The STS manual describes an optional GPS module (SPMA3173) that adds SAFE Plus features: the aircraft can fly a holding pattern on its own, return home and land by itself, and be kept from flying too far from the pilot. It also describes virtual fence modes and a separate Landing Assist Sensor (SPMA3180). The manual says installing the LAS alone is not auto land, and that with GPS it only assists the flare close to the ground. Treat these as optional extras, not a promise, since they only work when installed and calibrated.

Other Apprentice-adjacent options

Horizon sells other SAFE trainers that fit between and beyond these two. This guide's earlier research on the HobbyZone line found the Sport Cub S 2, a 617 mm plane weighing 61 g with its recommended 1S 150 mAh battery, and the AeroScout S 2 1.1m, a 1095 mm 3S plane weighing 853 g with a 3S 2200 mAh battery. Both were in stock at Horizon at the time. For wider comparisons, see our best RC trainer planes, the micro and park flyer options and the guide to the major brands.

Which to buy

• Choose the STOL S 700mm RTF if you want one box, a small yard or park, and a plane that stays under the FAA registration weight. Plan for short sessions and calm weather.
• Choose the STOL S BNF only if you already own a compatible Spektrum radio, a 2S 300 mAh battery and a charger.
• Choose the STS 1.5m if you intend to learn at a club field with an instructor and want the larger platform. Budget separately for a 3S battery and charger on the RTF.
• Skip hunting for an "E-flite Apprentice STOL" that does not exist. If a listing uses that name, check the model number against the table above.

FAQ