Jump to content

Avalon Build & Flight Log


Recommended Posts

satinet

As I don't really have anything else to do other than child care, I decided to tackle a build (when she's asleep).

I've had this model for a couple of years. There is nothing different about it compared to other f3x models in terms of build or concept.  It has a DP section and is made by Radek Munzar.

I'm doing a hybrid LDS system using the frame and pushrod but having an exposed horn and clevis. 1. I'm using what i got and 2. LDS has it's cons as many of you will know. For this situation i would rather have a more serviceable model but I like the frames of LDS and the solid linkage.

Price was very good on this model at the time. Layupis carbon of course. Not sure what. Probably c160 i would guess. 

DSCN0488.thumb.JPG.adade82b05312a3d0513fe97723e6a01.JPG

DSCN0481.JPG

DSCN0487.JPG

DSCN0486.JPG

DSCN0484.JPG

  • Like 2
Link to post
Share on other sites
satinet

The pictures don't quite show the colour on this m it's yellow with a captial YU and very shiny.

Any road, first job is to make up some quick and dirty jigs for the supplied 2mm g10 horns. 

Then get the horns glued in. I've only got west systems epoxy. At least I've got plenty of working time.

Trailing edge jigs are the only really reliable way I've found to align the horns down the years.

The horn is aligned with the hinge line. The aileron pocket is actually in line with the air flow, which is fair enough, but there won't be much play in this system and the arc of the pushrod will be in line with the hinge.

20200324_133120.jpg

20200324_143031.jpg

20200324_144413.jpg

Link to post
Share on other sites
satinet

This is what the linkage and pushrod will be like.

N.b the aero foil is relatively thick on this model so a reasonable servo horn can be used. I think the idea was to be good at high Cl situations. 

Clevis are fancy pants mpjet metal jobs with a pin and a retaining clip. They give very solid results.

Note this is the old servorahmen ids system not the current one with fixed rods.  This version did come with brass horns for the flaps but the model came with nice g10 horns which suit the clevis i wanted to use. 

Servos are bluebird something or other. 

20200324_172146.jpg

  • Like 1
Link to post
Share on other sites
oipigface

Tom,

Could you give a bit more detail about your horn jigs? Please.

Link to post
Share on other sites
satinet
49 minutes ago, oipigface said:

Tom,

Could you give a bit more detail about your horn jigs? Please.

Hi John

As you know on your flaps of the horns are even slightly different left to right you can end up with big differences in the travel which can be hard to take out with the radio 

The idea is to use the trailing edge of the flap/aileron as a datum point. This is done just be using some epoxy board or wood. The stopper controls the distance the horn is from the trailing edge and the thickness you build it dictates the height. One is made for the flaps and one for the aileron. So the control horn position is closely matched from left to right.

What i usually use is a 1.6mm (1/16") drill bit as the holder pin for the horn, as pictured. Most clevis pins are 1.6mm but obviously this needs to be correct for the clevis used.

Obviously the jig is used to hold the horn in position while the glue ******* dries. 

Two obvious caveats - 1) the width of pairs of control surfaces isn't always the same (left to right). You can measure this with a caliper - i.e. sometimes one flap will actually be wider than the other. But this can be compensated for.

2. The idea works less well the more tapered the control surface is as you need to accurately match where along the flap or aileron the jig is positioned laterally. And stopper will be aligned with the trailing edge and not the hinge line unless you use something round.

However most flaps don't taper very much and accuracy is actually less important on the ailerons where the travel is much less. When you have 80 or 90 degree flaps you really notice if you have uneven control horns.

 

20200324_193101.jpg

20200324_193038.jpg

20200324_193021.jpg

20200324_193014.jpg

20200324_192943.jpg

  • Like 2
  • Thanks 2
Link to post
Share on other sites
satinet

Horn jigs on my srtl. Clevis shown is the clevis used ob this build.

Note round ball stopper on the aileron jig.

20160925_122100.jpg

20160930_084813.jpg

Link to post
Share on other sites
isoaritfirst

Good stuff Tom.
I know that you would know this but for the thread,

 

Accuracy of horn placement becomes more critical as the horn gets smaller. 
LDS systems with the horn hidden in the skin can easily be out of sync if some type of jig isn’t used. It is easier to imagine that they would be easier than longer horns but inaccuracies are magnified by their smaller size. 
consider a horn length of 12mm. A 0.25mm error is a half the error that it would be on a 6 mm horn. 
 

  • Thanks 1
Link to post
Share on other sites
satinet

Absolutely Mike.  Once you get under the wing skin even fractions of a mm make a significant difference.

Here the flap horn length is about 12mm so its not especially short. i can pair it to a horn about 9 to 10mm on the servo. The old servorahmen system came with a number plastic horns. I don't care about getting 90 degree flaps.

  • Like 1
Link to post
Share on other sites
satinet

Left wing is the same as the right. Here is also the wing root. There are two 20x10mm ballast chambers. The model also has a ballast tube in the fuse.

The left flap is tiny bit wider than the right so i adjusted the jig a very tiny bit. 

20200325_110928.jpg

20200325_123233.jpg

  • Like 1
Link to post
Share on other sites
satinet

Wiring loom.  I used a fixed male connector in the fuselage. This gives more room for the wires than using the female side in the fuselage.

I use a floating connector on the wing root, hence the black heat shrink. I will enlarge the connector hole in the wing.  I've learnt from experience that i prefer one side to be floating. Failures on the flight line are no joke.

For soldering i use Laco plumbers' flux and a cheap soldering iron. Heat shrink from conponent shop.

N.b the manufacturer supplies the components for a loom. I.e mpx greens and wires with the servo connectors on. I would probably use thinner wire if i were buying it but it's good quality copper wire and I'm not concerned about a few grams for a slope/ f3f model.

 

20200325_112030.jpg

20200325_120801.jpg

20200325_120047.jpg

  • Like 1
Link to post
Share on other sites
satinet

My battery choices:

18650 - 3500mah or

21700 - 4000mah.

The 21700 is probably too big but we shall see.  They're already soldered both so that's time saved. 

20200325_121131.jpg

Link to post
Share on other sites
isoaritfirst

A little tip I was given recently. 
A blob of Blue Tack makes a great holder for small items that need soldering. 

Link to post
Share on other sites
satinet

That's a good idea. I use the jaw things.

Link to post
Share on other sites
satinet

Time to put the wiring loom in the fuselage. 

1st step i get a spare female connector as a jig and connect this to the loom. Everything that does want sticking was given a coat of mould release wax (i.e beeswax)

Then tape this to the outside of the fusleage.

I mixed up some old 30 minute epoxy which i wanted to syringe in from the opposite side through the joiner hole, but it was too thick, so I reverted to the glue on a stick approach.

This way you end up with a nicely glued in connector, that is square to the wing root, without blathering glue mix all over the place. Nice and neat.

Repeat for the other side - this is a bit harder as there are more wires in the way, but basically the same.  

 

wiring loom jig.JPG

wiring loom jig2.JPG

wiring loom jig3.JPG

wiring loom jig4.JPG

  • Like 1
Link to post
Share on other sites
oipigface
22 hours ago, satinet said:

Hi John

As you know on your flaps of the horns are even slightly different left to right you can end up with big differences in the travel which can be hard to take out with the radio 

The idea is to use the trailing edge of the flap/aileron as a datum point. This is done just be using some epoxy board or wood. The stopper controls the distance the horn is from the trailing edge and the thickness you build it dictates the height. One is made for the flaps and one for the aileron. So the control horn position is closely matched from left to right.

What i usually use is a 1.6mm (1/16") drill bit as the holder pin for the horn, as pictured. Most clevis pins are 1.6mm but obviously this needs to be correct for the clevis used.

Obviously the jig is used to hold the horn in position while the glue ******* dries. 

Two obvious caveats - 1) the width of pairs of control surfaces isn't always the same (left to right). You can measure this with a caliper - i.e. sometimes one flap will actually be wider than the other. But this can be compensated for.

2. The idea works less well the more tapered the control surface is as you need to accurately match where along the flap or aileron the jig is positioned laterally. And stopper will be aligned with the trailing edge and not the hinge line unless you use something round.

However most flaps don't taper very much and accuracy is actually less important on the ailerons where the travel is much less. When you have 80 or 90 degree flaps you really notice if you have uneven control horns.

 

Gosh! That's LOTS of detail. Thanks, Tom!

  • Like 1
Link to post
Share on other sites
satinet

Making up pushhrods. The clevis is very slightly loose so I used some glass cloth to tighten the fit. Once this was dry the excess was just cut off.

The aluminium pushrods are quid flexible with this ids system. So i glued in some lenthgs of carbon tube to stiffen them up.

 

DSCN0498.JPG

DSCN0502.JPG

DSCN0505.JPG

  • Like 1
Link to post
Share on other sites
satinet

It's important to get opposite servo horns on the servos to sit at the same angle.  this was done with a bit of subtrimming and both aileron pushrods were cut to the same length. I.e same servo horn angle and same length pushrods. Same position horns in the wing = same travel. 

No need for adjustments post gluing - there will be plenty of travel. Servo and frame glued it with the aileron taped at neutral. 

Result is a very solid linkage but one where the arm and servo can easily be removed. Happy with how it turned out. Flaps next 

I had to dry over night as i am working with slow epoxy.

DSCN0506.JPG

DSCN0507.JPG

  • Like 4
Link to post
Share on other sites
satinet

Putting the flap servos in - pretty much the same as the ailerons. It's important to take time to line up those flap horns.  It's pretty easy to work out how much travel you are going to have. My servo arm is about 10mm and my flap horn is about 12.5mm. I have allowed 100 degrees or so down rotation so 100*(10/12.5)=80. Should end up with about 80 down. Might be more than I need so I can go down to a smaller arm. .N.B linkage geometry does matter to travel but it probably won't make that much difference unless you do something very funky. That's why there isn't a need to mess about with servo arms and linkages after the fact. Make everything the same in pairs and work out the travel. 

flap3.JPG

flap1.JPG

flap2.JPG

DSCN0523.JPG

Link to post
Share on other sites
satinet

I add a bracing to the servo. This might seem a strange idea given there is a servo mounting to make removal easy, but it does help to spread the loads a lot and saves the wing skin for going soft. They are only glued in a with a weak/microballoon heavy mix so can be cracked out easily. 

DSCN0532.JPG

  • Like 1
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Who's Online   0 Members, 0 Anonymous, 18 Guests (See full list)

    There are no registered users currently online

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.