Checking alignments

 Acroduster  Comments Off on Checking alignments
Nov 192019
 

It is always a good thing when the magic red lines end up where they should..

all the zero’s!

Making the bottom bracing means you have to get everything lined up properly. You don’t want to start pulling this out of whack. Since I went through all the trouble making the clevises, I might as well use them. Officially the stab side is made by drilling a hole in the flattened streamline tubing. Guess no one will know except me (and you). It is also easier at the moment to make them that way, so that I can slip the streamlined ABS tubing over the 3mm rod.

Printing a quad of 3mm streamline fairings. ABS and 215 mm high. Layer height is 0.2 mm. dimensions are 3.9mm x 10mm deep (OD), just enough for a 3mm rod to pass through..
busy at work as we speaks. I added a base for stability, the previous set started to wobble ever so slightly at the top of the print.

In order to give the plastic some time to cool down and to provide some stability, I print a ‘cloverleaf’. The ends are barely touching, it comes apart very easy. First trial looks good. The texture looks quite rough here, but a small amount of sanding smooths things out in no time at all. I still want to add a layer of glass, and tidy the ends to make it all look very much like ”scale”.

another variation, I made this after looking at WW1 aircraft.
These are on a full size one.

Also made a slightly different version, this one has a tapered front section. It looks nice too. I only flattened one side, where the screw goes, that leaves a bit more flesh for the thread on the other side. In the picture above I drilled it for a 3 mm bolt, reduced the bolt-head to 3.9mm, so it sinks into the top bit. Anyway, 3mm is too big for a 6mm rod, but the idea is good. (Since I now have the lathe setup better, the results are better too. Not good, not machinist good, but hobby good enough for the job. I drilled the 3mm screw with a 1.5 mm hole, in order to put a locking pin through. Yes, too much work. I agree (for now)

The smaller the parts, the longer it takes to make them.

 Acroduster  Comments Off on The smaller the parts, the longer it takes to make them.
Nov 122019
 

There must be a law for that! Anyway, at the moment of writing I have half the brackets done. Most challenging part is cutting without cutting meat-ware. So far all fingers are present. Material is 0.8 mm stainless, not the easiest to work with. I had some nice clevises from Pete Tindal*, they look good and do the job just fine. They were meant to be used with glue and a 3 mm carbon rod, but cutting a 4mm thread in the hole works great. Cutting a 4 mm bolt to size and drilling a hole for the wire seems to work. I might tidy up the bolt end, it does not look to grand. ( *only people of a certain age will know Pete)

Pete Tindal clevises. He who keeps everything has a lot of junk.
Top elevator, cables, bottom streamline tubing.
Polishing everything will make it look better!
cut narrow 6.5 mm strips
some elbow grease required to make them look nice
and bend them the required 129 degrees. (141 degrees for stab side)

Elevator servo stuff

 Acroduster  Comments Off on Elevator servo stuff
Nov 052019
 

Servo needs to be hidden under the seat, so I built some bits to do just that. All overkill of course. I also remade the pivot of the control stick. The washers I has used had an internal diameter of 3.2mm. The bolt was 3mm. Very sloppy! Same with the link at the bottom. It took some time, but now it is all slop free!

Update: did not like the crossbar, it interfered with full up. So changed things a wee bit, still same servo position.

Elevator control chain.

 Acroduster  Comments Off on Elevator control chain.
Nov 032019
 

Need to get from the (future) servo under the seat to the back-end in an orderly fashion. I’m using the full size method as guide. Main part is the reversing bar behind the seat. It has to be zero play. No play, whatsoever. After the usual fiddling around for a while, I got it sorted. It’s a once you install it, you can never change it construction. Failure here is no option. The bolt at the bottom prevents the assembly sliding out of the bushings. It does not support anything. The 2 little square supports were reamed out to provide a zero play bushing.

Next will have to be the construction of the stick assy, and the mechanical interface to the servo. Lot’s of fun ahead!

pushrod is for illustration only.
and something for the pilot to hang on to.

I am only installing the main stick, front seat is ”occupied”. Not sure yet if I am going to use a separate servo(s) to drive it. Separate seems safer, since there is a reasonable mass in this contraption. Might build a pilot with power arms 😉

full down..
full up, looks like it’s enough..

The stick has to be fixed with AN4-22 bolt, 4 washers, AN310-4 nut and a AN380 1-2 cotter pin. Yup, M3 bolt and nut will do fine! (for the curious: AN4 is 1/4 ” = 6 mm. So 2 mm would be scale. Since those 2 mm bolts are usally quite soft, I won’t waste my time installing one, they will rattle loose in no time at all. The nut is a castle nut so you can put a cotter pin through the bolts hole to stop it going awol. I know you wanted to know all this.

..more tail-bits..

 Acroduster  Comments Off on ..more tail-bits..
Oct 282019
 

..many times you have to make parts before the other parts that need to go on before the parts that you need to fit to get the job done. This was one of them. Needed to make more hinges. Not difficult, just fiddly, and a bit dodgy, since I try to cut them on the lathe, with a dodgy china cutting wheel going full speed. However, hats of to the china-folk, I have not had a single one fail on me. So far I have used approx 20 odd discs on this project.

cutting some hinge-parts.

After checking the tail, I noticed the main spar was bend. This appears to be almost inevitable when you heat bits. I decided to simply cut the middle, and add a sleeve. Problem sorted. My metal working skills don’t go so far that I can predict how much distortion I will get. Of course I could make very expensive, very heavy jigs. yup, I could..

fudge, I had to cut the front, because the rear was not straight after brazing..

A bit of a showoff.. Starting to look like it wants to fly!

1569 gram, still smiling

Just one more weighing session. 1569 grams as seen here. Good stuff!

enough done for today!

And I am calling it a day. All in all it does not seem much, but I am happy with it! The section above weighs 300 gram. As a comparison: the ”light” elevator from my 2.5 meter Extra weighs also 600 grams. Ok, there’s 2 servo’s included in that figure, but still..

Finished the rest of the elevators today, another milestone reached! Also bolted the motor back on to get a feel for the CG. At the moment I am still slightly nose-heavy, so things are good! I don’t expect to have to add any of the grey gravity stuff.

yes, that’s 288 grams!
That’s the elevator horn-thingy sticking out there. Added a bit of wrap around as well.

The rear stabilizer mount consists of a single bolt, as per original, the front is made up of a few gussets. I probably simplify that part. Not sure how, but simpler as original. (too many small bits that fall apart when you heat things up, is the main reason)

Lets make some tail bits.

 Acroduster  Comments Off on Lets make some tail bits.
Oct 262019
 

The plans call for square tube at a few locations. I don’t think it will be a problem to use round tubing. As usual, use what you got! I also don’t think I have enough space for the 2 central bearings, another fudge expected there.

remember: full size!
..bend some tubes..

My template has a more rounded outline at the outer elevator. Might have to redo it, since the big one has a smaller radius.

test fit, looking good.
..and preparing for the next fun parts