Zagi 400X

 

History Why Build a Zagi? Can you teach yourself to fly? Information for Beginners Elevon Control Horns The Flying Field Local Hazards Setup

Zagi 400X Receiver: Hitec 555 Servos: GWS-S3002STD Transmitter: Futaba 6XAS

History

Having previously built a traditional balsa glider (a Capella) I lost interest in flying radio control aircraft for a number of reasons, but mainly because of the difficulty of having to go somewhere to fly, difficulty getting someone to teach me how to fly, and the problem of one small error leading to a large repair job.

Many years later I decided to have another go since I could fly in my 'back yard' (see below). I was going to repair and fly the Capella - however, there were a number of problems:

A small amount of, admitedly unscientific, research led me to conclude that something like a Zagi would be just what I needed. Living in Australia that meant that whatever was available locally would be what I want. It turned out that the 400X was what was available.

The 400X has turned out to be great, I can use it to slope/wave soar on moderately windy days or just use the electric power on still days.

Why Build a Zagi?

The main reasons I can suggest for building a Zagi are:

• They are fun to fly!
• They are simple to build.
• They are simple to repair.
• It takes a big accident to do serious damage to a Zagi.

Can you teach yourself to fly?

This is a subject of much debate: however, you can teach yourself to fly a Zagi. Having said that there are a few provisos:

• You need somewhere suitable to start flying. Suitable means you can't damage anybody or anything! Suitable also means an appropriately sized area, while it is possible to fly a Zagi in a small space you need a larger space as a beginner.
• A simulator (for example FMS, or RealFlight) is essential. Put in enough time on the simulator and your first flight will go fine! In my case I spent a lot of time on RealFlight practicing circuits and landings in the PT-40 trainer and then using the Zagi model in FMS to practice flying and landings with the Zagi.

Information for Beginners

1. Before you buy and start building your Zagi get a simulator and use it to practice your flying. Once you have built your Zagi you will want to fly it immediately and the way to avoid big disapointments is to have some simulator experience. The simulator will let you get used to control-reversal when the Zagi is flying towards you and also give you experience at determining which way the Zagi is going when viewed from a distance - this is not always as easy as it sounds.
2. Before you start construction read all the info on the Internet. I recommend www.yourzagi.com as the place to start. I followed the instructions at www.clubzagi.com for constructing a 400X and finished up only 0.4oz overweight and with the CG in exactly the correct spot! Read all this material before you start, a lot of it may not make sense when you read it but you will know later on when you need the information you read earlier.
3. When you buy your Zagi kit purchase an extra roll of coloured tape so that you can make the top light coloured, and the bottom dark coloured. For a beginner this will really help, believe me. If you stick to the light top/dark bottom this will match the FMS Zagi model, and this aids with transfering your simulator experience to real flight!
4. Have faith in the 3M Super77 glue! Yes this will really hold the thing together. Here in Australia we can still get the original Super77 - and yes, it will hold the Zagi together.
5. During construction you will shape two elevons, make a paper template for the finished elevons. It is almost certain (like death and taxes) that you will need to make replacement elevons! It is easier to make a replacement if you have a template.
6. It is absolutely essential to either colour the battery pack, or attach a streamer to the pack. If you don't you are likely to never find the battery pack again on the first serious impact. The 'break-away' construction is really important, once the battery pack is ejected the bulk of the energy goes with it and the damage to the Zagi itself is reduced - but you still have to find the battery pack! In my case I opted to go with the streamer solution, I used florescent pink surveying tape as the streamer.
7. If you are following the ClubZagi instructions make sure that elevon hinge nearest the motor is positioned so that the elevon control horns attach to the elevons on top of the hinge. This precaution stops the elevon breaking at the weak point created by the holes in the balsa elevons. See below for pictures of this.
8. If you have a Futaba transmitter there is a chance that you will need to reverse the throttle 'servo' to get the ESC to function correctly! I thought that I had a broken ESC until I accidentally powered it up with the throttle at MAX and found that moving the throttle to MIN and then back to MAX cause the 'beep-beep' from the ESC... from here I found some Internet references that confirmed what I had deduced - that the throttle needed servo reverse.
9. Attach the propeller firmly. If you don't the propellor will fall off mid flight, then you have the problem of watching the propellor to see where it is falling at the same time as gliding your Zagi to earth. This is not as easy as it sounds if it is only your third flight.
10. Pay attention to the correct elevon alignment prior to your glide test. Although it looks 'funny' all the information on the Internet and in the manual is correct regarding the elevon neutral position - follow the line of the lower wing surface.
11. The Zagi will glide further that you think once you get the throw right - make sure you have lots of space.
12. When you get to the preflight glide tests you need to throw the Zagi fairly hard. The major damage so far to my Zagi was during the initial tests as the Zagi hit the ground... eventually I was frustrated and threw a bit harder and the Zagi glided perfectly... almost hitting a number of obstacles... remember you need enough space for this...
13. Eventually you will get tired of the thing hitting the ground and you are going to decide to just go for the throttle... what you need to know in advance is that when you hit the throttle the Zagi will tend to head left... so be ready!

Elevon Control Horns

If you are following the ClubZagi instructions make sure that you place the elevon hinge nearest the motor so that the control horn will attach in the centre of the hinge. This is shown on the right. This requires a bit of planing because your natural inclination is to place the first hinge near the end of the elevon.

If you don't put the hinge in the same place as the control horn then the chances are that the edge of the hinge will be just to one side of the control horn and the moment you have a small accident the elevon will break along the line of the hinge tape, and also possibly through the holes for the control horn - as show here. When this happens you will need the elevon template you made earlier...you did make one didn't you?

The 'Flying Field'

As you can see there are a number of 'interesting' features here:

• Landing something with wheels would be a real problem.
• The ground slopes away in all directions so you need to get the landing correct or else the Zagi glides off down hill.
• There are lots of trees to get stuck in, especially as there is normally a lot of choppy air on the down-wind side of the hill.

On the plus side:

• In most winds there is some slope/wave lift at altitude over the hill, so you can easily soar with 25% throttle for 30 minutes. In the right conditions there is enough lift to power off completely.
• You get great views while flying. The altitute is 950 metres above sea level, with views to the Great Dividing Range to the east.

Local Hazards

One of the local hazards are eagles. We have at least one pair of large eagles that are frequent visitors, they soar along the ridges with effortless ease. Unfortunately they have tried to take the Zagi home for lunch! This was very disconcerting when it happened - I was on 'final approach' trying to land the Zagi at the same time as trying to manouver to avoid the eagle grabbing the Zagi with its claws! Other smaller birds of prey don't appear to be a problem and they will happily soar with the Zagi without trying to catch it. However, the eagles appear to see a Zagi as lunch! Perhaps because they have a wingspan that is larger than the Zagi and they will naturally prey on other birds.

This guy is fine if you are a Zagi - not so good if you are a rabbit. We think it is either a Little Eagle or a Whistling Kite, the wingspan is fraction smaller than a Zagi. These birds are happy to hunt while the Zagi is in the air and don't appear at all distracted as the Zagi flies along the ridge with them.
These are the large Wedge Tailed Eagles that we get hunting in our area. Wing span is larger than a Zagi. To date they have only been in the area on one occasion while I was flying the Zagi and on that occasion one of the pair attempted to grab the Zagi. The bird stayed just above the plane with its legs dangling down - attempting to get directly above it.

Setup

Parameter	Low Rate	Normal Rate
Elevon Throw (Aileron)	+/- 10mm	+/- 14mm
Elevon Throw (Elevator)	+/- 6mm	+/- 8mm
Elevon Mix	+60/-40
Max Travel	80%
Rate (Aileron)	75%	100%
Rate (Elevator)	75%	90%
Exponential (Aileron & Elevator)	-20%	-20%
Sub Trim (ch2)	+40
Throttle correction PMx1	ch3->ch1 L/D -10
Throttle correction PMx2	ch3->ch2 L/D -10
Allup Weight	750 gms (25 oz approx)