Lola FPV
Published by George & Peter,
The Lola is a multipurpose fixed wing FPV ship that would suit a wide range of skill levels and needs. Coming from a molded sailplane background we decided to incorporate some of what we had learned from that facet of the hobby. The fuselage of the model is a molded fiberglass with carbon reinforcements throughout the boom. Not only does this make for an excellent sleek finish, but a extremely true and accurate fuse, not to mention extremely rigid with a high level of durability.
The wing is a traditional built up balsa with glass reinforcements in the center. It has a two piece wing for easy transportation. This is a 4 servo wing meaning that in addition to ailerons there are also flaps, one more way of gaining even more control of your model.
This model comes in two variations, an ARF (airframe and hardware only) and a PnP (servos, motor, esc included and installed, Just as RX and flight controller...if you wish), Both at reasonable prices with parts and advice available with just a phone call or email away. We are also glad to do full builds in shop on a customer by customer basis. Our team is experienced and passionate about the hobby and FPV.
The Lola will take a 10" prop max, we are currently running a 9x6 with good results on a 3542 1200 kv with power the spare.
For the CG position:
We started at 3" back from the leading edge, at the root, we have moved it back about .25-.5" since and are pleased with it there. I would recommend you start with the forward CG (3") just to feel it out, then adjust as you see fit.
Wing extension all mounted up, and I found a 9x7 master airscrew gf3 bullnose. 25 amps WOT. With wing extension I should be fine.
We currently have an APM unit installed not the Pixhawk, although we are a little more fond of the Pixhawk, but we had the APM collecting dust that is what we opted for. For the airspeed sensor it works really well to use an epoxy puddy (JB weld has some and it is usually available at a Home Depot, Lowes, or Ace Hardware) stuck to the leading edge of the wing with the sensor pointed straight out, works like a charm and is an easy install. Also if you look at the attached picture there are premolded slots in the fuse that would make a wonderful mounting point for the sensor. Either way would work great.
Tha canopy was mounted with tape for our test flights to allow easy access to the electronics. Canopy latches are far more secure and would be the best way to mount this piece.
All of the surfaces are hinged from the factory for a low drag and strong joint, It is done better than I could do personally.
I attached a few more pictures of the plane, the pictures shows the Plug and Play, but the ARF kit is identical excluding the level of pre-installation (ie servos, control horns, motor pre mounted and installed).
The ARF includes all necessary hardware to complete the model, control horns, servo linkages, wing and stab mounting hardware, motor mount, skids and various nuts and bolts.
The wings bolt on, then are further secured with the bands. Alignment tabs keep everything true and locked in place, due to this I am confident that there would be no issues with just the bolts......but as they say, better safe than sorry!
Here are some pics of the fpv gear installed.
I decided to steal my mad mushroom 1.3ghz antenna from my ground station. That is a BEVRC 400mW vtx, with the heatsink exposed.
On the other end is the Rangelink with an ibcrazy dipole hot glued in. I had to sand the wing down a bit. I also added some weight to the rangelink side( 6 quarters was all it took).
The sony HAD II board camera is recessed in a slot I cut in the canopy. I left the flat spot open for a pan/tilt when it gets to that point.
On the inside is the apm. I did pick up some 45cm df13 cables to extend the gps further away from the high current esc wires, but cannot use the 6 position because it is a 6 to 6 pin, while apm 2.6 needs the antiquated 6 to 5 pin.
The rat's nest is horrendous, and I am open to suggestions on how to clean it up.
I had in mind using locking cat 6 connections for the 2 wings.
Right wing: Vtx (4 wires), 2 servos (2x3=6), total of 10 wires.
Left wing: RL (3 wires ppm+ 1 rssi)+ 2 servos (2x3=6), total of 10 wires.
The servo trays are really nice.
The pnp servos are so snug they just have a pressure fit. I went in and put a piece of packing tape on each servo, then some thick double stick tape, and finnaly the servo cover. All the play was removed.
Mounting fpv gear in the wings: Mounting your video transmitter on one side and the RC receiver on the other wing tip will allow the greatest separation. Make sure you have equal amounts of weight on both sides of the wing, otherwise it will want to roll.
The front section of the wing "d-box" has holes from the wing root to the tip. Then there are holes from the front to the back half of the wing. This allows easy stringing of wires for fpv gear, and a gps module.
Start by cutting the last bay on the wing on the bottom side(white). Use a sharp exacto blade to get a clean cut but careful not to punch though the top of the wing. Then, get a piece of thin string and clamp a small fishing weight on the end. Feed the string from the wing root down the d box to the tip using gravity, where it will be easily reachable from the bay you cut. Make a loop at the end of the string, loop the fpv wires through the string loop and wrap in tape. Braid or twist the servo wires to reduce interference. Also make sure to use plenty of length of wire. Extra can be trimmed later. Pull the string back out with the wires. Make knots on both ends so you don't accidently pull it back out . Finally cut a hole on the bottom side of the d box by the root and feed the wires through. Finally solder the equipment on or do the crimp connections. Use double stick tape and glue the video tx and receiver in. Seal it up with monokote, or packing tape. I highly recommend using a ppm signal to use less wires in the wings if using an autopilot like the pixhawk or apm.
Construction and First Flights
I have a couple of days flying my Lola so I thought that I would write down what I learned so far.
First impressions with the kit:First thing I noticed is No Instructions. None to download that I could find. It’s a nice looking kit. Fuselage very nice fiberglass and is very strong. The wings are very nice build up construction and are very stiff D-tube construction. Kit includes hardware, servo extensions, and motor wire extensions.
FUSELAGE:The fuselage is incredable roomy inside due to fiberglass construction (no foam to take up a lot of room). The tail boom and tail has a fiberglass doubles inside that makes it very strong and rigid but it’s a bit heavy in the tail. A lighter weight fiberglass doubler would have saved some weight and made it easier to get the correct cg.
The fiberglass canopy is nice and it has a built in flat camera mount. They don’t provide any canopy mounting hardware. I see that most are using tape so that’s what I did. Not very elegant but it works. You probably need a better solution is you have a camera mounted on the canopy.
The kit includes some parts for making a belly skid but it was not obvious how they are installed. I am flying off grass so I don’t need that.
WING:First thing I noticed was the incredibly heavy half inch by 13 inch solid carbon (or maybe fiberglass) rod wing joiner. A lightweight carbon tube would have quite a bit of weight.
The tape hinges were not perfect but usable and had no edges coming loose. After a few flights the hinges look to be ok.
My left wing has a bit of twist. It’s twisted so that it has washout so at least that’s good from a tip stall standpoint. I tried to use a heat gun and twist it straight but it didn’t work. The D-tube wing is too stiff. They must have a problem with the manufacturing process for building wings. It took quite a bit of up aileron on the left wing to get it to fly straight. After I got it trimmed it seams to fly ok.
STAB:My stab had some warp but was easily straightened with a heat gun. Tape hinges were good. When I bolted the stab and wing on the fuselage the alignment was excellent.
The small nylon screws seamed weak and felt like they might brake when I tightened. I replaced them with some stainless steel fasteners that I had on hand.
TAIL:Since the tail is built into the fuselage the only thing to do was install the hinges. There are CA hinges provided with the kit.
CG:After reading of some cg concerns I did some calculations using low and standard efficiency tails. For sport aerobatic RC airplanes 5% to 15% static margin is a good design range. I used 15% to be on the safe side.
First thing I did was take some measurements. I found out that the advertised wing area of 560 sq" is a little high. I got 538.5 sq" for the wing and 132 for the stab.
CG for 15% sm standard tail efficiency = 3.7" from wing le
CG for 15% sm low tail efficiency = 3.0" from wing le
For FPV a cg range of 3.0 to 3.75 would be good. 4.0 if you use low rates on elevator.
I flight tested between 3.5 and 4.0" and it was always stable. Forward cg will cause the elevator to be less sensitive and may be easier to fly. Aft cg may require elevator low rates but will have less trim drag.
Flying:I am using a 4s power system. A Turnigy G10-810 with an APC 10x7e prop. That pulls a little over 30 amps on launch. I used a CC ICE 50 lite that I had on hand. Futaba 14SG radio with battery voltage telemetry. HXT900 servos, they are low cost but I have found them to be more reliable than Hitec servos of the same size. No FPV gear installed yet.
I tried several battery configurations. Two 4s 3000 in parallel for the forward cg testing. This is a bit heavier than I like. I settled on a T5000.4s.30 battery that gives a good cg and 45 minutes of flight time.
Hand launch needs a good hard toss and some up elevator trim. I programmed a transmitter switch to a mixer giving a little up elevator for hand launch. Then switch it off as soon as it starts a nose up climb.
This is a very clean and low drag aircraft. At half throttle with my power system it cruises plenty fast. I fly 30-40 minutes and put back 3100-3600 in my 5000 pack. The wing is very stiff so I don’t think you have to worry about high speed flutter. If I wanted to go faster a higher pitch prop would probably do it.
So far the only changes I have planned are a lighter weight wing joiner rod and a canopy mount. I don’t currently have any ideas on the canopy and would appreciate any suggestions.