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Spacewalker balsa build - Additional notes

Shaul

Active member
#1
In this thread I'd like to add some notes on top of the monumental work done by @willsonman in his thread.
I am quite sure I would have quit this build had I not used the above thread.

Now, as I am concluding my work I'd like to share a few minor points. It might save people some time and reduce the frustration level of the builder.
Let's start with a fresh entry.
 

Shaul

Active member
#2
Leading Edge Problems
In my case, the 1.5mm Balsa sheet, B6, that is used to create a nice wing curve was not accurate.
It should cover the wing between A16 and A15. However, in my case it was too wide.
In addition the leading edge balsa part, G1, is not wide enough to fully cover A15.
My mistake was to allow B6 to cover A15. Big mistake. See what happens:

Before Sanding.png

The shape of the wing is distorted. You can also see that G1 is not wide enough to fully cover A15.
At first I added some wood to sandwich G1. I now think it was not necessary.

Solution:
If you did not trim B6 to fit into place you will have to do it now:
Insert a scalpel into B6 so that it is flat on A15.
Now go along A15 removing a thin stripe of B6. Be careful not to damage E1-E3.
Remove the stripe.
Now fit B6 into place and glue it:
After Sanding.png

Note that the gap was closed and the shape of the wing restored.
Also note that some sanding was applied to A15.
The Leading Edge looks great!
 

willsonman

Builder Extraordinare
Mentor
#3
This is an excellent addendum and something I did not cover comprehensively in my own build. Thank you for adding to the knowledge base!
 

Shaul

Active member
#4
Battery Hatch & Cowl alignment

The covering sheet of the hatch B3 is too long and needs to be trimmed, despite the misleading picture in the manual:
2018-11-22 12_53_34-Window.png

It should not protrude past the front plate F6|A2.
The results should look like this:
IMG_0570.png


Now, the cowl is neatly aligned with the hatch.
Note the the cowl and the hatch do not overlap. The cowl does cover the firewall F9|C1|A1 as seen here:
IMG_0568.png


That way I did not have to trim the cowl.

Well, The motor is indeed mounted too low so I had to enlarge the front aperture:
IMG_0571.png


I used a Dremel equipped with a sanding drum. Took me 5 minutes at most.

I will edit this post if needed.
 

Shaul

Active member
#5
The aileron servo bays

I have followed willsonman in his work. I would like to share a few elaborate photos of my work and a few points that I think should be considered.
The standard servos arms are quite short and will barely suffice as you can see here:
closeup02.png


Place the servo so that the arm does not touch the bay-cover when in full throw. You should also consider using a longer servo arm and/or limiting the end-point on the transmitter.

Here are a few photos of the servo mount I created.

servocase01.png
servocase02.png
servo01.png
 

Attachments

willsonman

Builder Extraordinare
Mentor
#6
Using full throws, I found that the ailerons had good authority. While I did have to limit my throws in my radio, as-designed performed quite well. Still, for a bit more aerobatic performance, this is a good thing to note.

In terms of your hatch and cowl... The overlap of the hatch and F6/A2 is not misleading. It is designed in such a way that the balsa sheeting is sandwiched between the cowl and F6/A2. While your method works as well, as-designed does create a more seamless look. I have not had any issue with the designed configuration. What I DID have to do was bevel the front part of the firewall (F6/A2) to account for the slope of the hatch and allow clearance of the balsa sheet between the cowl and the firewall. It was a minor fitting issue quickly addressed with a sanding bar.

Yes, the included motor mount is garbage. In no way should it be used if you are going for a more scale look. The motor center line is off using it. While minor, the thrust line not being aligned with the datum of the aircraft can induce unfavorable flight characteristics. That is why I used the motor mount from Great Planes.
 

Shaul

Active member
#7
Thank you for these inputs.
I did not consider bevelling the firewall. Much better solution.
I am currently using the stock motor mount. I will comment on the plane characteristics after my maiden flight. Too windy at the moment, next week supposed to calmer.
 
Last edited:

Shaul

Active member
#8
Some final notes:
Wheels and Wheel pants

The hole in the wheels is too small for the landing gear's axis. You will have to patiently enlarge the hole and also remove the paint from the axis.

Then, we get to the wheel pants:
The stock bolts are too long as they prevent the wheels from freely spinning. I replaced them with M3x8mm bolts. I used washers to prevent the bolt from cracking the wheel pants.
Bolt.png


Here is how the whole thing looks like:
WheelPants.png


Arrow B points at the bolt head.
Arrow A points at the bolt that fixes the wheel pant in place. I have tightened this bolt only after I had finished building the plane. Only then I could figure out the exact angle.
Lastly, I've put a drop of Loctite where arrow C points.
 

Shaul

Active member
#11
Maiden Flight(s)

The D day has arrived. Medium wind (15 Km/h), blue sky and a wide concrete runway.
Testing the controls, deactivating the EagleTree Guardian 2D/3D Stabilizer and starting a slow run.
Some UP and more power and the SpaceWalker is airborne!

It sways quite violently so I pull UP to get away from the ground then I manage to calm it down. It turns a little heavily using the ailerons. The rudder has only a minor effect. I need increase the throw of the rudder.
Once controls are trimmed (only minor trimming needed) the model is stable. I can remove my hands fro the sticks for 20 seconds and it is still more or less on its course. Nice.
It feels a little slow and heavy. I am perhaps too cautious (that is, terrified) so I am far from full thrust. However, this slow movement has its pleasures too.

I now start landing. I cut the throttle and it just gently glides to the runway. As the rudder is hardly effective, I miss the runway and land on the grass besides it. No damage, very smooth landing. I resume breathing.

The next flight was better as I added 30% exponent to the Elevator and the ailerons, less swaying. I still need to improve the Rudder.

To sum up: This is a slow and stable model. Easy enough to fly and to land. Taking-off needs some experience. Although it is not trainer, it can serve as your second model, just after you have ceased crashing your trainer. More experienced pilots will find it perhaps a little boring.

I haven't yet tried aerobatics with it and I'm skeptical if it can do more than a large loop. I might try a smaller prop (I now use 15x8) and higher throttle curve to see if it can be livelier.


 

Shaul

Active member
#13
Attaching the Dummy Engine to the cowling

After a few flight I've come to the conclusion that the plane is a little tail-heavy. Since the battery is already set at its foremost position, I need to add some weight to the front of the plane. The Dummy Engine weight about 70g so I hope it will do.

This it how the front of the plane looked before I set to work:
before.png


Note that the inside is the standard build, which leaves plenty of space for additional weight if later needed:
No_Cowl.png


Here is how I attached the Dummy Engine parts. I think the outcome looks fine so if you like it you may wish to follow my footsteps. This might save you some time:

I used pencil to mark a line just above the dent in the cowling:
start-line.png
then I stretched the line and marked the beginning of the Dummy Engine at 40mm from the front of the cowling.
Then, I placed the part in place and marked where to drill a 2mm hole.
I attached the part using one of the 8 supplied 2mm bolts. I used one of the supplied wooden washers so the cowling does not crack.
WoodenSpacers and Bolts.png


Now the part is loosely connected:
40mm Mark.png

The arrows point at the line I marked using a pencil and at the 40mm point I mentioned earlier.
Note that the Dummy Engine part is the LEFT part and that its exhaust pipes are at the bottom. It is important as the holes are not symmetrically spread.

Now is the time to mark and drill the remaining 3 holes and to fix the part in place. Do not tighten the bolts to firmly or it will distort the shape of the cowling.
Do not forget to use the wooden washers and to put a drop of "Loctite".
This is how it should look from the inside:
Inside_cowl.png


and from the outside:
finished.png
 

Shaul

Active member
#15
I use 4S 3300. After five minutes of easy flying, just several take offs and landings, it was still powerful. I believe I could squeeze at least eight minutes of flying out of it.
 

Shaul

Active member
#17
Control throws

After quite few rounds I have some insight regarding the control throws.
The ones recommended by the vendor are OK but please bear in mind they are indeed "Sporty" as indicated.
I set the elevator throw to +/-17mm to get a smooth flight.

Note that my model tended to slip when turning.
I have managed to correct this by employing differential aileron:
- When an aileron goes up, the throw is 17mm.
- When an aileron goes down, the throw is only 9mm.