Strix StratoSurfer

© Mark Qvale - January, 2018

New plane! Ready for some graphics and many fun flights

Introduction

I decided to try something different and having never gone down the Bixler style road, the Strix StratoSurfer seemed like a good place to start. Also, after reading much about this plane, I decided to start with a larger motor/prop combo. For flight management/control I'll be starting with an Omnibus F3Pro flight controller to keep it light and simple.

Here then is a collection of my build notes and eventually a flight review of this plane.

General Specifications

Distributor - ReadyMadeRC, USA
Aircraft - Strix Stratosurfer
Build Date - January, 2018
Update - 5 February, 2018

Airframe Type -	Top Wing FPV Specialist	All-Up Weight -	55oz (1565g) w/ 4S/7000 Li-ion Pack
Wingspan -	59 inches (1500mm)		56oz (1586g) w/ 4S/5200 Li-Poly Pack
Length -	39 inches (1000mm)	COG -	65mm - 70mm @ Wing root (Stock)
Wing Area -	2.95 ft^2 (27.4dm^2)	Wing Load w/5200mAh/4S -	18.9 oz/ft^2 (58g/dm^2)
Motor -	Sunnysky 2216-1250kv	Max Continuous Power (4S) -	470 watts (4S)
Propeller -	8x7 Aeronaut Cam Carbon Folder	Max Prop Power -	405 watts @ 2550ft ASL
Static Thrust & Prop Speed -	1145g & 94mph @ 2550ft ASL	Static Thrust/Weight -	0.72
Battery Type -	4S1P Lipo -or- 4S2P Li-ion	Battery Capacity -	5200mAh/10C or 7000mah/3C
In flight efficiency -	TBA	Flight Time -	TBA

Components/Flight Gear

Below is the approximate layout of installed components:

Power Set-up

For power on this build I have chosen the Sunnysky X2216-1250kv. For an ESC, I started with a HobbyKing Blue Series 40A with a pair of Low ESR capacitors added. I am now using a Hobbywing Flyfun v5 40A unit to get active freewheeling and its awesome 8A, super quiet BEC.

Motor - Sunnysky 2216-1250kv
ESC - Hobbywing Flyfun V5 40A
Prop - Aeronaut Cam Carbon Folder, 8x7

For more informaion on setting up a pusher folding prop - How To - Set-Up a Pusher Style Folding Prop

Battery - Multistar 4S/5200, 10C or a 4S/7000 Li-Ion

Mounted with a 7x6 Aeronaut folder

Motor Mount

For the motor mount I designed and printed one that spaces the motor 6mm rearward and 19mm above the original mount to get the clearance needed for 7" & 8" props. Additionally, I printed a cowl to protect the motor and direct cooling air to the rear of the motor.

Motor mount parts

Mounted

Front and rear views

ESC Mount

I decided to design and print a simple mount to hold the ESC. It mounts with four M3x6mm nylon screws and a wire tie to hold the ESC. This print is sized for a 25mm wide ESC.

ESC craddle

Flight Control

For flight control I have chosen the Omnibus F3Pro from Banggood. It is very inexpensive and in my experience completely reliable.

Omnibus F3Pro

w/iNav 1.8.1

All wired up!

FC Mount

To mount the FC I drilled out the existing mount holes to 2.3mm then tapped them to M3 and flooded the tapped holes with thin CA. This makes them more than strong enough for a set of rubber M3x6mm stand-offs.

FC mount

RC Control

For radio gear I am using my standard DragonLink V2 system. I have mounted the DL dipole inside the verticle stabilizer. The RX is mounted on a printed deck below the GPS mount.The printed part is glued in with contact cement but you could also use E6000 or UHU-POR.

DragonLink UHF antenna

RX mount

GPS Mount

For the GPS I created a mount plate to replace the white plate on the rear of the fuse. This is sized for a Ublox Mini M7 GPS.

Mini Ublox M7/M8

FPV Gear

For an initial setup I am using the stock foam cowl piece with simple mounts for the FPV camera, VTx and HD camera. I will be changing to printed canopies as I did on my MiniTalon builds to get a more aerodynamic profile and cool looks! Here are the initial components and a picture of their mounts:

VTx - RMRC 800mw, 1.3G
FPV Camera - HS1184 with 2.8 lens
HD Camera - Mobius Mini

Initial FPV gear

Airframe

Stabilizers

On the tail linkage I used the stock linkage bits with Hextronic MG14 metal gear digital servos. Of course the standard 1/2" Blenderm tape was added to the hinges for strength.

Wings

Nothing new or special here. I added 1" (25mm) of 3 mil laminate to the leading edge. Linkage is the same as the elevators and servos are Corona DS929MG's. Blenderm on the hinge line here too.

Fuselage

The beauty of a plastic fuselage is it is already very durable. Because of where I fly (and land) I still felt I needed a little more protection on the nose and rear skid so I designed up a couple of skids which conform to the fuselage shape. The new nose skid also has a provision for a bolt-on tow hook which I will add later. These are printed in ABS at 80% infil for durability. For glue, I used E6000 which is similar to UHU-POR and Beacons FoamTac.

Front skid

Rear skid (with excessive glue)

Kit/Build Review

I opted for the bare bones kit because I live and fly at 2500ft or more altitude and it has been my experience that most PNP setups are underpowered and supplied with servos that could be improved, etc. With that said, all in all this is a really nice kit. The linkage components in mine are well made and sized perfectly. There are good, solid stiffeners in the control surfaces and having the channels pre-cut in the wings for servo wires is a big plus.

The plastic fuselage is also a big treat. Using plastic makes for an enormous amount of room, it is very stiff and has a nice battery tray pre-installed.

Here are some of my personal points for improvement:

Please! Stop producing kits like this that will only take a 6" prop. Anyone serious about fixed wing FPV is going to weight it down with gear and packs and a 6 inch prop is not an efficient way to go on a plane of this size. It is also very noisy. A lot more planes would be sold if there were more motor/prop options.

So, include an optional large prop motor mount for those of us that want to spend more money on motors and props.

The screw holding the tail together should be much closer to the bottom of the fuse so you can get it out. A socket head cap screw would help as well.
The four screws holding the wing and motor pod in place are difficult to get in and out which makes it difficult to break this down for travel. Changing them to socket head cap screws would be a big improvement.
Change the main wing spar to a more common CF round tube that slips into a tube in each wing panel. This would make it much easier to take the wings apart. I simply can't get mine apart without damaging them.
Put some stabilization inside the fuse on each side of the wooden FC mount. This piece is well glued but it still moves around too much. I inserted two pieces of foam down each side to dampen the movement.

Maiden!

Maiden - 01 January, 2018

The maiden was uneventful in terms of drama (well, except on the launch!) which is always a good thing. The weather was perfect with temp at ~70F a very light breeze and clear skies. From a flying standpoint, the Stratosurfer flies very well, very controllable, nice yaw response and can be landed slow enough (for me!) without the use of flaps which I haven't installed. The prop I selected, an Aeronaut 7x6 folder was a bit weak as far as climb-out and launch and I will be changing this to an 8x6 Graupner folder for the next flights. The iNav FC needs some tuning and board alignment adjustment but it did its job and kept the plane stable when asked.

Maiden Day - 15 January, 2018

Post maiden!

Updates/Mods/Changes

Released Part Updates

Offset Motor Mount

I added stiffening ribs to the motor mount plate as requested by several people. Parts list below is updated.

RX Mount

I added two 2.55mm holes with bosses to the bottom of the mount which you can tap to M3 so you can use nylon screws to hold it down. I originally had it glued down with contact cement which came loose.

Changes & New Parts

APM Mini 3.1 Flight Controller

After ~18 flights I finally got tired of trying to get the Banggood Omnibus F3 Pro flight controller to perform like an APM. So, I have now replaced it with an APM Mini 3.1 I had "on the shelf" which is basicly an APM 2.8 in a small package. It flys excellent although I will need to add a compass to get all the benifits from the APM.

Hobbywing Flyfun V5 40A ESC

Got another HW Flyfun V5 in and immediately replaced the HK Blue Series 40A. Nothing wrong with the Blue Series but the Flyfun is a much better unit and with their DEO Technology, also known as Active Freewheeling, these units run amazingly cool at any throttle position and are more efficient at power management. Additionally, they come with a 5.2/6.0/7.4 volt BEC that will deliver a full 8 amps/20 amps peak (tested).

New Hobbywing Flyfun v5 and APM Mini 3.1

52143 & 52144 - New FPV Camera Mount

Another mod from my maiden setup is a nose mounted FPV cam. I've seen pictures of others done with a nose cam and I have been on the fence about cutting into it as plastic isn't as easy to patch up as EPO should something go wrong or not work-out. Looking through all my extra gear I found I had a spare Fatshark 700tvl v2 FPV cam which fits very well inside the nose with only the lens needing a hole in the fuse.

I designed then a 2 piece mount for the camera consisting of a camera mount and a lens hood. The lens hood is glued to the cam mount with ABS glue which is incredibly strong (you must print in ABS for this to work!).

Fatshark camera mount assembly

Shown without lens hood

With lens hood glued

Once the two pieces are glued together, a hole is cut in the nose and the assembly is glued in (I am using E6000 glue). The mount is shaped to fit so that the camera and its lens hood are looking down about 2 degrees but some fine "Dremel" tunning is required. It is also a challenge to get it in there as there is not much room for fingers and hands.

View from the inside

Bottom view shown with front skid

The last bit is optional but recommended. There are two small 2.55mm holes in the mount that can be used for a small screw on each side if you want more strength in the mount. You can either tap the holes to M3 and use nylon screws or just use self taping screws. These screws are not shown here but will be added. The camera should lightly press into the mount tightly, if not, put a layer of tape on the sides to tighten it up.

52145 - GPS Mount for 36mm Sqaure Ublox

Because I changed to an APM flight controller, I needed to add a GPS unit with a magnetic compass. This mount then is to fit the new GPS unit.

Mount with cover

52147 - Prop Strike Protection Plate

Because the plastic fuselage is quite thin and very easily cut, I decided to add a prop strike protection plate. This is also because I do not trust the integrity of the foam supporting the motor mount which could easily break away from the motor pod.
The piece shown in the picture is longer, side to side, then the final print version.

Shown with an APCe 8x6 prop

52148, 52149, 52150 - New Small Canopies

Finally finished the small canopy shape and have released (below) two canopies and a mount that screws down to the plywood deck.

Mounted on the plane, Pan and Tilt version shown

Plain canopy with mount

Canopy mount

Future Canopy!

Below is a canopy concept I am working on for this plane. It is a full length unit that hopefully will be printable as one piece. I haven't developed the cut-outs for the long canopy yet but here is the basic shape and how it fits on the fuselage. With a shell thickness of 1.4mm the weight would be close to 42g.

Long Canopy concept

Stay tuned!

Low Profile Wing & Motor Mount

It is well known, the vast majority of fixed wing FPV hobbyists over-power their planes and add more FPV gear than needed. In addition, a very large number of us are always looking for the best flight efficiency to get the longest extended range and/or flight time and this means we will try any motor/prop/battery combo we can fit. This generally ends up being a larger motor with low Kv to run larger, deeper pitch props at a lower RPM.

How the manufacturers of planes marketed as “FPV” rigs don’t understand what the community wants in an “FPV” plane is a complete mystery to me!

"On ALL fixed wing planes designated as FPV planes, we, the FW FPV community, want the ability to use larger motors and props than you or your designers think are appropriate"

In the case of the Stratosurfer, putting a larger prop on the plane requires an offset or extended mount. The problem with this idea is the stock wing/motor mount is not designed to accommodate a larger motor and it is certainly not designed to handle an offset mount of any kind.

It’s a design problem. The stock mount has very little foam support and even with a stock motor set-up it is very likely this mount will eventually fail on a hard landing. In fact, directly in front of the stock mount piece, the supporting foam is mostly hollow. Here is a general sketch of the stock mount and you can see there is no hard plastic structure tying the motor mount part to the wing screw insert so the only support is the foam which, again, is mostly hollow.

Below is a picture of a failed mount showing how small the area of foam support is. The area highlighted in yellow is all that supports the motor and the motors center of mass is above the weakest part of this support putting it in an extreme stress condition.

So, at the very least, the designers should have tied the mount piece to the rear wing screw insert. This would transfer most of the load into the screw mount. Below is a part illustration of this idea:

OK, my solution

My solution is a two part (5 piece) wing & motor mount that are tied together with a 4mm CF tube. This gives the same wing clamping force as the original two screw inserts but adds an immense amount of strength to the motor mount which is now integral to the wing mounts and their screws. It is also extended to allow 8” props. The total mass of these pieces is 24g more than the foam mount with the motor mount insert.

There are 5 parts to this solution:

1. Front wing mount cover

2. Motor mount

3. ESC wire cover

4. Motor shroud (optional)

5. 4mm x 2mm Carbon Fiber tube

Now, because this is a low profile solution to conserve weight, the front foam piece needs to be carefully cut to match the front wing mount piece. Below is a picture of mine with the foam piece cut to match and a spring latch added to replace the magnet. Shown with a 2216 motor and an 8" Aeronaut folding prop.

Coming soon, I will have a longer 1 piece canopy to go with all of this.

See below for these new parts!

Project 3D Print Files

Below are the 3D print files shown in this build.

General print notes:

1. All parts are shown printed in PushPlastics ABS filament

2. Motor mount and front & rear skids are printed at 80% infil, all others are 20-40%

3. All weights are as printed and subject to change depending on printer/slicer set-up

4. Print orientation is dependent on printer/slicer set-up, please rotate if necessary

All content is ©Mark Qvale and available under Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International license unless otherwise noted or agreed to in writing.

Image	Part Number	Part Description	Weight	Print File	Compatibility Notes
	52136	ESC Mount, 25mm	6.7g	52136.STL	Fits a 25mm wide ESC
	52137	GPS Mount	3.3g	52137.STL	Mount for a Ublox Mini 7M GPS
	52138	Motor Cowl	4.0g	52138.STL	Motor and mount cover
	52139	RX Mount	4.2g	52139.STL	Mount platform for DL RX UPDATE - Added screw holes
	52140	19mm Offset Motor Mount	3.1g	52140.STL	Motor mount to allow 7 & 8 inch props UPDATE - Added stiffener ribs
	52141	Rear Skid	2.0g	52141.STL	Glue on rear skid
	52142	Front Skid	12g	52142.STL	Fuselage glue on front skid (print on edge)
	52108	VTx Saddle Mount	2.7g	52108.STL	Saddle mount for a 26mm x 50mm VTx
	47010	HS1184 Camera Mount	4.9g	47010.STL	Simple box camera mount for the Surveilzone HS1184 FPV camera

New parts!

Image	Part Number	Part Description	Weight	Print File	Compatibility Notes
	52143	Stratosurfer Fatshark FPV Mount	3.2g	52143.STL	Fits the Fatshark 700tvl v2 FPV camera
	52144	Stratosurfer Fathark Lens Hood	1.3g	52144.STL	Lens hood for two piece Fatshark mount
	52145	Stratosurfer 30mm GPS Mount	4.6g	52145.STL	Mount for 30mm x 30mm (hole centers) Ublox GPS
	52146	Stratosurfer 30mm GPS Cover	4.2g	52146.STL	Cover for 30mm x 30mm (hole centers) Ublox GPS
	52147	Prop Strike Plate	5.8g	52147.STL	Extra protection against prop strikes
	52148	Small Canopy Mount Plate	3.7g	52148.STL	Mount to hold the small canopy in place
	52149	Small Canopy with Attachment Deck	27g	52149.STL	Fits the lightweight pan and tilts and roll gimbal
	52150	Plain Canopy	25g	52150.STL	A plain deck which can be cut to fit cameras, etc.
	52151	ESC Mount, 28mm	6.7g	52151.STL	Fits a 28mm wide ESC

Low Profile Wing & Motor Mount Parts

Image	Part Number	Part Description	Weight	Print File	Compatibility Notes
	52156	Stratosurfer Front Wing Mount	11.6g	52156.STL	Low profile wing mount and cover
	52153	Stratosurfer Extended Motor Mount	18g	52153.STL	Bolt-on motor mount that can use an 8" prop
	52152	Stratosurfer ESC Wire Cover	3.6g	52152.STL	Cover for the ESC wires on top of the wing
	52154	Stratosurfer Motor Mount Shroud	2.3g	52154.STL	Optional glue-on motor shroud