Technical data main module (manufacture data)

Type: extended version FY-21AP gyro 3-axes stabilization with RTH
Input voltage: 4.0 to 6.0V
Current draw: 52mA @ 5,0V
Size: 55× 33 x 20mm
Weight: 20g
Temperature range: -25°C – +70°C
Maximum rate of rotation: < 1200 °/s

Application: normal plane with and without aileron, v-tail with and without rudder, and planes with delta mix

Compatible remote control systems: Robbe-Futaba PPM / PCM 1024 / PCM G3 Mode Graupner JR PPM 8, PPM 12, SPCM Mode Multiplex PPM 8, PPM 12 with UNI Mode 1,5ms

Technical data GPS module (manufacture data)

GPS Data refresh rate: 10Hz
Interface features: TTL Level
Baud rate: 38000 baud
Data Bits: 8
Stop Bits: 1
Parity: None

Packaging and content

The package arrived well packed in an air cushion. The accessories were extensive. The module itself is about the same as the FY-20A, except for the 2 additional connections for the second switching channel and the GPS module. It is 55mm x 33mm x 20mm and weighs only 19g. Unlike many similar products, the module is not covered with heat shrink. The housing is robust and can be unscrewed.
With the circuit board removed it only weighs 9.5g.

Also included are five 18.5cm JR- servo connectors, one plastic shock mount, two pieces of Velcro tape and an illustrated English manual.

Functional principle and installation

Like the FY-20A, the FY-21AP offers, stabilization on three axes (elevator, rudder and ailerons). It’s even possible to control models with v-tail or delta mix. The model type is selected via plug contact. Three gyro sensors and a microprocessor provide the stabilization.

In contrast to the basic version FY-20A, the FY-21AP offers additional functions like RTH (return to home). This feature provides a semi-autonomous return to home function. For this the GPS module has to be connected to the FY-21AP main module. Flying circles with only the autopilot is also possible. So you can enjoy the landscape and let the autopilot do the work.

Unfortunately the system needs a y-cable for the second aileron. So it’s not possible to set an aileron differential via the transmitter. If the servos are running in the same direction, it’s possible to buy a y-cable with switchable inverting.
In the test we tried to misuse the rudder axes for the second aileron, but failed. Using only one aileron for stabilization made the RTH function too difficult.

The installation is done in a few steps. You should install it in a position with good airflow, to have a constant temperature. Otherwise the gyros will drift too much. The manufacturer suggests resetting the module before the flight if the temperature differential is above 30 °C. The same should be done after a longer break. Possible problems of the gyro drift are explained in the Flight Test chapter.
The FY-21AP calibrates itself after powering up. Once adjusted, you are ready to fly.
The module is mounted with Velcro tape onto the shock mount. The printed arrow on the module must be in the flight direction.

Flight modes

- Switch IN 1 – mode 1: Deactivated – normal RC control – no stabilization

- Switch IN 1 – mode 2: Auto balance mode – aircraft will enter horizontal level flight, when the transmitter’s control sticks are centred. Deflections are limited and the FY21-AP will not allow any acrobatic flights.

- Switch IN 1 – mode 3: Auto balance mode with fixed altitude – aircraft will enter horizontal level flight and stay at the current altitude, when the transmitter’s control sticks are centred. Deflections are limited and the FY21-AP will not allow any acrobatic flights. Attention: throttle position has to be set manually, because it won’t be controlled by the module. It is possible to set a fixed throttle position, but this can cause problems with non self stable air crafts. Especially if the down thrust is not correctly adjusted. You have to test this yourself how the plane reacts. Alternative you can use the Eagle Tree OSD Pro in combination with the FY-21AP. This OSD can control the throttle for the right level flight. For example to use the throttle channel separate with the OSD Pro without use of the rudder function of the OSD.

Autopilot modes

- Switch IN – mode 1: RTH (Return to home) – The model flies independent and stabilized back to the pilot. At arrival the model flies circles with a diameter of around 200 meters. Attention: throttle position has to be set manually, because it won’t be controlled by the module. Alternatively you can use the Eagle Tree OSD Pro in combination with the FY-21AP. This OSD can control the throttle for the right level flight. For example to use the throttle channel separate with the OSD Pro without use of the rudder function of the OSD.

- Switch IN 2 – mode 2: autopilot deactivated

- Switch IN 2 – mode 3: ACM (auto circling mode) – The model flies independent and stabilized circles with a diameter of around 200 meters. Circle position is position of activation, independent of the home position for RTH. Attention: throttle position has to be set manually, because it won’t be controlled by the module. Alternative you can use the Eagle Tree OSD Pro in combination with the FY-21AP. This OSD can control the throttle for the right level flight. For example to use the throttle channel separate with the OSD Pro without use of the rudder function of the OSD.

The modes are switchable during the flight. You will need two 3 position switches at the transmitter. If you have only a 2 position switch, you can only choose between mode 1 and 2 or between mode 1 and 3.
The ailerons are connected through a y-cable with the FY-21AP. Rudder and elevator are also directly connected to the module. We had no problems with the connections during our test. All plug connections were stable and their connections secure.

During the first start-up you have to check the correct rotation directions of the servos and the rudder effect in the stabilization mode. With the help of the three rotation potentiometers you can set the maximum deflections and the correct rotating direction. We suggest using as much as possible small deflections to get the right feeling during flying. Too big deflections can cause the loss of the model, if you are not fast enough to deactivate the stabilization during the flight.
Close Attention is required and the maxim “Less is more” is valid here.

Flight tests

Chapter 1 – stabilization

For the maiden flight we chose the Bormatec Maja. We did a test flight with and without the shock absorber during low and high wind conditions. We flew the Maja without stabilization to a secure flying level and switched to mode 2.   In this mode the FY-21AP fully controls the model. We watched amazed how stable the Maja was, even with its weight of around 3kg. Even stronger gusts of wind had no negative effects. This is one of the main advantages of this system. We could not control the Maja that accurately while the wind was blowing so much. There was no noticeable deviation in the flight path. The Maja flew stable and smooth.
Controlling during mode 2 is a little unfamiliar. It is like having 100% expo on all channels, but we quickly got used to it. The model was still very controllable and we felt secure knowing the FY-21AP would take over if we needed it to.

You need watch the flight speed during autonomous flight; especially with non-self-stable models, as it could result in a stall.
The FY-21AP does not like vibrations. That’s why the shock absorber is very important. We made test flights without this absorber and the FY-21AP reacted with uncontrolled deflections. Tests with gas driven aircrafts showed that the FY-21AP will work with reasonable damping of the module, like foam or cotton wool. During our longer tests in different weather situations we noticed a little drift because of temperature fluctuation. We could fix that really fast and easy with a manual calibration. That’s not a big problem and conforms to standards.

For comparison, The FY-21AP was tested in a Multiplex Cularis. Except for the much tighter fit, the system performed as described above. Only the fixed altitude mode worked, because the self-stableness of the Cularis is more precise.
The FY-21AP has consequently no problems with electro sailing planes or even motor planes.

Chapter 2 – ACM mode, autopilot and fixed altitude

ACM mode

ACM stands for: auto circling mode. We powered up our plane and waited until the FY21-AP gets its home position via satellite link. The led signals shows the actual state, which is described in the manual.  After that we did a short pre flight check and started the plane. As stated in the manual, the ACM mode centre is the actual model position where you activate the mode. We flew away with the plane and activated the ACM mode. Immediately the plane started a constant turn, sometimes a right, sometimes a left turn. The radius was about 120 meters. We noticed that the plane banked a little too much, because of the relatively tight circle. This can be a problem at slower speeds, where the plane looses altitude during the circles. Generally the ACM mode worked reliably and the model was never out of control.
As an important side note: You can take back the control of the model immediately and at anytime in any mode.

Autopilot – RTH mode

We started our model again and flew away, then activated the RTH mode. The autopilot initiated a turn immediately and the plane flew straight back to its home position. Upon arrival the FY21-AP switched automatically to the ACM mode and flew circles until we took back control. After this successful test we did the same with transmitter turned off. We programmed the fail-safe and tested it. As above the autopilot flew the plane without problems back home.

We would have liked the FY-21AP to control for flight altitude, but alas no. If you activate the RTH at a 600m altitude, the plane will come back and circle at 600m. So you would probably need binoculars to find your plane in the sky, if you lost the video signal. You have to find the right throttle position to hold the altitude in the RTH mode. Just manually switch on RTH and play with the throttle stick to find the right value.

Fixed altitude

This mode is to hold the plane at a fixed altitude. Our tests showed that this mode is only useful if the plane does not climb or sink very much during different throttle positions. The FY-21AP is not able to control the throttle so; too much push from the motor can override the deflections of the FY-21AP, which can cause problems.  A mechanical correction of the throttle is necessary. Unfortunately this is not possible with all planes, so a correction of angle can help here.

Conclusion

The FY-21AP is a much better solution compared to the basic version. With the optional OSD you can get a fully graphical flight system with auto pilot. The different functions do their jobs reliably. The small enervations do not diminish the use of this product.
Especially for the price of the FY-21AP, you get a very good package.

Scoring

Pro

+++ versatile additional functions compared to the basic version
+++ reliable operation
+++ very lightweight
+++ small size
+++ uncomplicated and easy assembling
+++ modes switch able during flight
++ extensive accessories inclusive

Con

— throttle is not controlled by autopilot
— no second aileron connection
– little gyro drift in the case of intense temperature fluctuation

Further information about this product

• FY21AP Review (German)
• FY21AP – Discussion and Support Thread
• FeiyuTech Homepage
  
• FY21AP Manual
• Antenna tracking with FY21AP (Video)
  
• MAJA as platform for FY21AP review (English)
• MAJA as platform for FY21AP review (German)

Cable duct

The new wing has a continuous cable duct. It is 40mm wide and 15mm deep. With the new version, it is easy to fit all the cables inside the wings. Cutting is now no longer necessary. There is enough room for external sensors or lighting systems.

Internal wing spar

Compared to the old version, wing spars cannot be seen from outside. They are now rotated 45 degrees, thus rhombic assembled inside the wing. This improves the stability of the wing and is noticeable during the assembly. The main disadvantage is that the spars are not easy to change like in the old version. However, the Maja is a tough plane and it takes a lot of force to bend the spars.

Wing fastening

Eariler in the MAJA test, we criticized the insecure wing locks.
The manufacturer has made a big improvement. The locking system is now the same as the fuselage; using Duro/Coroplast material. This method has proven reliable in many conditions thus there is no concern about loosing the wings in the air.

New wing profile

The Maja has a new wing profile. It’s a modified NACA 2412, which should improve the slow flight characteristics. The difference between the old and new wing profile can be only seen if you look very closely.
To feel the difference, we did a few test flights with the old and the new wings. Flying weight was brought up to exactly 3kg. We analyzed the flight characteristics of both sets of wings at a constant throttle of about ¾.
The resulting flight time was ~18 minutes with the old set and ~15 minutes with the new wings, neither times include gliding time. The lowest flight speed before stall was 25km/h for the old and 17km/h for the new version. Under 30km/h the old version was harder to control compared to 22-25km/h for the new wing design. We compared each wing on a second flight to confirm the results.
The tests showed a noticeable improvement in slow flying characteristics, which results in a slight decrease in flight time. This decrease in time will be barely noticeable under normal conditions.  Our tests were done under extreme conditions.
The results can vary with different power.

Our setup was the same as in the first part of this test:

Motor: Himax 3516- 1130
ESC: Simprop Magic Speed 42
Lipo: 2x 3s – 2450mAh parallel
Prop.: 10×6 Aeronaut Cam Carbon

Gliding and overall performance

The gliding performance of the Maja has improved with the new wings. The model does not loose height as fast as before. The landing approach is now a little easier. In sum the increase of gliding performance is the result of the better slow flying characteristics.

Conclusion

The new are an improvement and sport new features. The minimal decrease in flight time is only barely noticeable during normal flying.  This is because of the increase in gliding performance. The new wing has better stability and the new wing locks perform well even in rough conditions.
The company Bormatec continuously improves their models and upgrades as it goes.

Scoring

Pro

++ improved slow flying characteristics
++ improved stability of the wings
+++ new wing fastening
+++ continuous cable duct

Contra

– small decrease in flight time
– change of aluminium spars is more difficult

Result: good

Further information about this product

• Bormatec MAJA review – English
• Bormatec MAJA new wing review – German
  
• Bormatec MAJA review – German
• Bormatec MAJA discussion thread – English
  
• Bormatec MAJA discussion thread – German

We will test the flight characteristics with this new wing.
The experiences with the new wing will be added to the current MAJA review.

Here it is, the long awaited, much-desired aircraft which offers enough space for all your equipment and even can take some extra weight. You are free to choose how you lay the cables – without any spaghetti syndrome.

The “Maja” is developed by the German Borjet aeromodels company and is a real workhorse for FPV with a high loading capacity, high-quality flight characteristics and enough room for all your equipment.

We, the FPV-Community, had the honor of testing this aircraft exclusively. On the following pages you are going to find all the results.

A review by Markus Schumacher aka Mashu

Product description

“Maja“, probably called after “Maya the Bee”, is an aircraft made of black-yellow EPP. This material combines flexible rigidity and a high compressive strength in comparison to elapor, arcel, etc. Maja has a wingspan of 1.8 meters and is 1.2 meters long. The dimensions of its usable interior are:

• in the middle: 15.8 x 3,2 x 3,2 inch

• in the front: 15.8 x 2 x 2 inch

The model has been designed for a total weight of 3 kg. With the RC components recommended by the manufacturer it is ready for take off weight of 1.5 kg. This means an additional loading capacity of 1.5 kg. Equipped with two Li-Po accumulators (both 3700mAh) connected in parallel, according to the manufacturer, it can fly up to 1.2 hours.

The wings in three parts are pluggable and lockable. The Maja is used in the fields of aerial photography, measurement and air surveillance.

Packing and Dispatch

I was quite amazed when I had received the package. It was an unexpected big box having the dimensions of 47.2 x 12.6 x 12.6 inch. Compared with former deliveries, it seemed like the manufacturer had improved a lot the quality of its packing.

All parts were protected from damage: each component was wrapped in foil and closed by a tacker.

Components and Construction kit

The construction kit includes the following components (see photo):

• 1 fuselage with motor mount and firewall
• 1 elevator
• 1 rudder
• 4 canopy closures made of thermoset
• 3 wings with aluminum reinforcing profile (see also following part of report)
• 2 winglets for wings
• 1 EPP universal element for fuselage (for additional installations)
• 2 elements forming the nose
• 1 wooden motor mount
• 1 assortment of small parts (linkage, fixations, etc.)
• 1 construction manual in English/German
• Some remains of EPP (very useful)

The fuselage

The fuselage of Maja has a lot of refinements worth mentioning. The canopy, for example, is opened in two stages: first the forward half of the fuselage which is planned as the battery carrier, and then the posterior half of the fuselage, made for technical installations. For more stability the fuselage has some sheets of thermoset (plastic panels) pasted into the top and the bottom. So, the aircraft can even land on uneven ground without damaging the EPP. The canopy hinges are made of this robust material, too. At the beginning, I was skeptical if it could withstand any stresses, but the manufacturer guaranteed there will be no problem. I will see how it will handle the stresses. Another highlight are the wings, which can be adjusted. In case of additional installations this can be useful to adjust the center of gravity. On the picture below you can see the red cable gland for servo cables. The cables are lead directly into the fuselage interior. In the motor mount at the rear will be the firewall, the motor, the controller and two servo cables, one for the elevator, one for the rudder.

A special characteristic of the motor mount is that it can be removed for maintenance work. It is locked by plug-in pins. Unfortunately, it is necessary to remove the control linkages of the elevator servo when removing the motor. Furthermore, the cable gland for the motor mount and its RC cabling are already fixed. It is conspicuous here that the model has a high level of prefabrication.

The Canopy latch

This well-reasoned construction combines the upper with the lower half of the fuselage. When assembling the model, two closures are stuck on each side of the fuselage. These closures consist of plastic panels, too. So, after that the supplied plastic sticks are passed through to close the fuselage.

For a short moment I feared that I lose the sticks during the flight. In contrary to all of my worries, I noticed that it is fixed tightly when I first passed through a stick. A fabulous construction.

The Wings

As I have already mentioned, the wings are divided into three parts. The middle part is fixed permanently with screws on the fuselage. The outer parts of the wings can be plugged in and locked comfortably. So, the locking mechanism consists of an inflexible steel wire plugged into a pre-drilled perforation.

Building and Construction manual

The Construction manual

The construction manual is very short but meaningful and contains a lot of illustrations. At second glance, however, I saw some inaccuracies in the illustrations. Nevertheless, they are not engraving. I already contacted the manufacturer to point these flaws out to him and he assured a fast correction.

Moreover, I noticed that there is a lack of information about the rudder angle or the note to put some expo on the elevator during the first flight.

This tip I got from the manufacturer via e-mail (see also paragraph “Flight tests”).

The Building

Anyone who has some building skills will be able to build the MAJA without major problems. Before starting, make sure that you have all equipment and adhesives available. In contrast to elapor or arcel, we do not need any super glue when using EPP, but 5min Epoxy and a glue gun. Don’t worry about using hot glue on the joints, my reaction was similar. However, my experience with Epoxy and glue gun are very durable. Once these two materials were glued together, I could not separate them without damaging the parts.

With the exception of the motor mount and the rudder, I glued all the parts of the Maja with hot glue. For the other parts and the elevator I used 5min Epoxy.

I was surprised about the good overall bond strength. Nevertheless, I found some negative aspects:

1. EPP is known as a material whose strength fades by and by when stressed permanently. The manufacturer knows about this problem and added aluminum braces to the stressed parts. This is a good solution for the wings. Unfortunately, the manufacturer forgot to add braces to the elevator which is wobbly. Even if it does not break, it influences the control linkages of the elevator and thus the flight characteristics. The manufacturer should improve this, for example by pasting in a 3mm carbon/CFK rod.
2. As I have already mentioned, the motor mount is locked by 3 plug-in plastic pins and thus is also wobbly. The manufacturer could add some extra plug-in pins. In this way, the user can plug in as many pins as needed.

The ESC and motor can be installed in a universal way. The kit includes a laser wooden motor mount with a pre-drilled hole on the motor mount. With the help of threaded rods the motor is mounted firmly, the down thrust is adjustable.

The ESC is placed under the motor mount. So, it is cooled during the flight and the cables which lead to the motor are short enough. A perfect motor for the Maja is a brushless motor with at least 350 watts. The ESC should provide about 60 amps. The manufacturer also sells a motor system which is available on his web page.

The manufacturer added a nice feature to the Maja. The construction kit includes a nose which can be removed, fixed with Velcro or adapted to personal needs, for example when installing a camera or sensors in the front of the fuselage (see also “Usability for aerial photography, measurement and FPV”).

The manufacturer recommends four 20g mini servos. In my opinion, they have enough power to drive the model, even when loaded. For the wings, however, I recommend using digital servos. The manufacturer also recommends gluing the servos in the wing. I would say it is better to use installation frames for servos with covers.

Flight tests

After programming the rc transmitter, finally, the day came to fly. It was windy and gusty.

Pointing the Maja into the wind and a light throw, it glided quietly through the air with very little trim. It withstood the gusty winds and its flight characteristics were similar to a high wing airplane. Gliding with motor off was good but it lost height quickly. Using one quarter power of the motor it floats smoothly on a constant altitude with low power consumption. Equipped with two Li-Po´s (11.1V 3s 2400mAh) connected in parallel I got 20 minutes flying time. When I landed there were still 950mAh remaining in the Li-Po´s. For more information about the first flight, see also the video below.

Usability for aerial photography and FPV

The Maja has a lot of room for all your equipment. For comparison, you see a photo of an installed GF OSC-Cam 480TVL, EZ OSD and a current sensor:

The OSC Cam fits well into the nose – making it resistant to vibrations. The headtracker could be installed on the top of the fuselage. It can handle some extra weight without any problems.

Video transmitter

Even with high frequency video transmitter on 5.8 GHz, I got high ranges with the antenna position shown in the picture. The shadowing effect caused by the fuselage and the wings was impressively small. This is another further strength of the Maja.

The weather conditions were not good for long-term testing. In spring I will carry out further testing.

Scoring and conclusion

Pro

+ Material EPP, high compressive strength and flexible rigidity
+ Long flight time
+ High-quality flight characteristics when loaded
+ High level of prefabrication
+ Wings divided in three parts and lockable
++ Well-reasoned locking system
++ Wing spars made of aluminum
++ Extra EPP material for individual installations
++ Bottom side of the fuselage protected during landing
+++ Center of gravity adjustable by wings
+++ Generous amount of space available

Con

- Construction manual partially inaccurate
- Motor mount is wobbly
- High initial purchase costs
– Elevator is wobbly – no spar

The Maja is a well-reasoned product which offers a lot of space for own design and installations. It is a good aircraft which will withstand the requirements of our community and other pilots for a long time.

For beginning users of FPV it is only suitable to a limited extent because of the high initial purchase costs. For advanced users of FPV, however, it is highly recommendable.

Further information about this product

• Bormatec MAJA review – German
• Bormatec Homepage
  
• Bormatec MAJA Discussion thread (English)
• Bormatec MAJA Discussion thread (German)
• Bormatec MAJA – Review of the new wings (English)
• Bormatec MAJA – Review of the new wings (German)
• MAJA as platform for FY20A review (English)
• MAJA as platform for FY20A review (German)
• MAJA as platform for FY21AP review (English)
• MAJA as platform for FY21AP review (German)