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Author Topic: first indoor - ministick build  (Read 2360 times)
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fitnezz
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« Reply #25 on: June 14, 2017, 10:07:44 AM »

Yeah thats all fun things todo! About the bearing, really go for a pigtail bearing. You can see how I did that in a video underneath. After few wire bendings gets in blood Wink Allows for thrust settings and props exchanging. If you dont have teflon washers, hard plastic from soda drink caps, i.e. red cocacola cap does the job well enough!

https://www.youtube.com/watch?v=xGmP43LpLGk
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FF - flying first! - building second?
Rossclements
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« Reply #26 on: June 14, 2017, 01:43:09 PM »

This is another good source!
https://www.youtube.com/watch?v=IAnm1gXUyx4&t=66s
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Skymon
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« Reply #27 on: June 15, 2017, 03:08:26 AM »

I made a lot of progress last night on my second Quark.
I spent a while selecting what I felt was light wood.
I have a nice 1/4 inch sheet that I stripped some sections off of the edge.
My fuse and stab are now half the weight of my original one - at 0.23g
But I feel the boom is a little tender.
So I contemplated changing it for a tougher piece of balsa, but then I thought, hey why not build a lighter stab instead?
That's tonight's challenge. This will also reduce the weight even further.

I tried an aluminium thrust bearing but it snapped so I went back to a pigtail and it worked ok.
Went down a size in the wire across the model. Having thinner wire helped in forming it up.

I ended up with a wing that is the same mass as my first one, despite using nicer wood.
I think I went a little too chunky on the sections especially for tip plates and ribs, but it's nice and sturdy.

Si
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BR549
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« Reply #28 on: June 16, 2017, 07:31:27 PM »

Keep at it with the thinned Duco. It's been a revelation for me since I got it figured out.

I got some micro-applicator bottles from Hobby Lobby. Put some acetone in the bottle, squeezed in some Duco than mixed it. Then fiddled with the mixture until I got a consistency that works for me. Now I double and triple glue all my joints and they a super strong.

Bob
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Skymon
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« Reply #29 on: June 20, 2017, 05:39:08 AM »

I got ministick three in the air last night.
It came in at 0.54g which is a lot better than my first at 0.85
Weight loss was mainly due to better wood selection for the motor stick.
Quark 1 had a stick weight of 0.47, this one has a more svelte 0.23. I did have to change the boom though as my first was a little too flexy.
It didn't even register on my scales... the second hits it at 0.02.
I have ordered more accurate scales just though Smiley
I also used 10 music wire all the way through instead of the mix of 10, 11 and 12 called for in the plans.
I had a heck of a job trimming it until I realised the wing was on back to front!
I'm really not happy with the friction on the prop, it seems to drag when wound.
When there is no rubber the prop turns on the slightest waft of air, but loaded it just doesn't seem to rotate freely.
I'll see what I can do in the way of washers and stuff tonight.
I had some pictures but they seem to have fallen off of my phone...
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Hepcat
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« Reply #30 on: June 20, 2017, 07:24:08 AM »

Skymon,
Your willingness to try things and keep going WILL bring success.  Just a couple of thoughts on the rough running propeller: did you grind and sand the front of the front loop  on which the washers run and did you keep the washers small, certainly not more than about 0.06" diameter.  Also you mentioned cutting down all your wire diameters, which is good because steel is heavy, however if you went to 0.01" diameter for the propshaft it could easily be bending under the load of a wound motor and binding, particularly in the pigtail.
John
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Skymon
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« Reply #31 on: June 20, 2017, 11:27:56 AM »

John
Thanks for the input.
I did grind down the front of the bearing with a dremel.
I've got no washers in there yet, I've ordered some thin ptfe sheet and I've got a few punches to cut out small discs.
I was going to drill a clearance hole in the sheet and then pop a disc out with my hole cutter.
I've drawn a blank on teeny tiny washers.
I was also going to cut a tiny square of drinks can, drill a hole in it and add it to the back of the prop.

One thin I don't like is the side thrust on the prop shaft, it looks very ungainly to have the shaft not running parallel to the rubber.
Must be some side loads on the bearing.
I've added a tiny dash of GT85 to the bearing to lube it and the motor has silicone lube on it.

I am energised by the need to tweak and experiment, learning a new skill is a big driver for me. I like the fact I can learn how adjusting the wing, the stab and the prop affect the flight pattern. I can see possibilities for a Taguchi DofE exercise to show the interactions Smiley

I'm off to the park tonight to sling cat gliders skyward, the weather here is tropical!
I'm so near the one minute mark on my Sweepette 8".

Many thanks for taking the time to read my posts and offering help and advice.

Regards
Si
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Rossclements
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« Reply #32 on: June 20, 2017, 02:02:25 PM »

Of you don't like the left thrust n the bearing check out Bill Gowen's models, It is a nifty solution!

Ross
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Skymon
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« Reply #33 on: June 21, 2017, 03:09:20 AM »

Are they the ones with the rubber on the side of the stick?
I guess the stick flexes and creates an offset.

I can see the offset is done for a reason, it just clashes with my engineering experience of aligned drivetrains.
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Skymon
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« Reply #34 on: June 21, 2017, 05:30:32 AM »

Here's my latest Quark on the scales at 0.57.
Still a way to go to get the 0.43 minimum, but a worthwhile advance.
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Re: first indoor - ministick build
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Rossclements
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« Reply #35 on: June 21, 2017, 07:07:08 AM »

No, Look at one of his plans in the gallery. The wingposts are set up differently than normal.
I cant post the plan here.

Ross
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frash
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« Reply #36 on: June 21, 2017, 07:54:53 AM »

Bill Gowen puts one wing post on one side of the motor stick and the other wing post on the other side of the motor stick to give left thrust with a straight prop hanger. This leaves motor and prop in a straight line with the motor stick.

Fred Rash

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Skymon
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« Reply #37 on: June 21, 2017, 08:07:58 AM »

Aha!
Neat solution Smiley
I'll have a look - are these ministick designs?
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Skymon
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« Reply #38 on: June 21, 2017, 08:10:43 AM »

I got them - LPP and A6 and F1M.
The F1M looks a bit like a ministick but bigger.
I like that idea but I guess it depends on endplates to 'steer' the plane.
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Skymon
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« Reply #39 on: June 21, 2017, 08:12:45 AM »

Another please for advice.
I have been adding turns to my motor and have got to the point where the model doesn't like to climb. It appears to be suffering a lot of torque where the inside wing drops and it enters a death spiral.
Running on the lower turns it glides nicely loosing a little height each rev, but when I go above 400 turns it really suffers...
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adanjo
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« Reply #40 on: June 21, 2017, 01:21:57 PM »

Another please for advice.
I have been adding turns to my motor and have got to the point where the model doesn't like to climb. It appears to be suffering a lot of torque where the inside wing drops and it enters a death spiral.
Running on the lower turns it glides nicely loosing a little height each rev, but when I go above 400 turns it really suffers...


Add wash-in on the left wing. Or, wash-in on the left and wash-out on the right wing, and add a little more angle of attack on the wing.
Aki
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Skymon
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« Reply #41 on: June 21, 2017, 01:33:36 PM »

Looking at the wing it has a subtle twist giving exactly the opposite effect.
Time to correct that...
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Rossclements
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« Reply #42 on: June 21, 2017, 02:04:07 PM »

The tip plates help a bit, but the motor stick effectively has left thrust. I have done this on a few A-6 models and it seems to work well.
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Skymon
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« Reply #43 on: June 21, 2017, 02:15:37 PM »

I straightened the wing first then added a lititle wash in toothed inboard tip and yay, it works.
Then I added a tiny piece of drinks can to the property as a washer and now I'm tapping the ceiling!
Fantastic.
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Skymon
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« Reply #44 on: June 22, 2017, 07:32:06 AM »

Many thanks for the help and assistance yesterday.
I found I had a number of issues.
1 - Friction. My prop has no bearing material at all, just balsa on steel wire. I added a tiny scrap of aluminium drinks can (2mm square) with a hole in it to the prop shaft and glued it to the hub. The result was a great increase in revs and power. From a slowly sinking pane to a plane that was tapping the ceiling on 400 turns.
2 - Wash in/out. My wing was warped, in the opposite way to what's required. Using a little steam I straightened it out, then I used a bit more to drop the trailing edge of the inside wing. I had no idea what wash in was before, I know understand it is effectively changing the angle of attack of the wing across it's span. So there is a little more lift from the inside corner that keeps the plane level. This worked really well and I now understand a concept I've been hearing and reading about for years.

It's all great progress!

As a result of understanding wash in, I added a bit to the tip of my Sweepette 8" CLG and I got my best time ever - 56 seconds in some really still air last night. I am now looking at building another one with better wood in an effort to break the minute Smiley

Best regards and thanks for all the help
Si
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Skymon
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« Reply #45 on: June 27, 2017, 02:47:37 AM »

I popped in to K&P Aero and picked up a winder last Friday and I've been adding lots of winds.
My lightest QUark was circling the ceiling last night, with the prop pinging every now and then, on 600 turns.
Pulling rubber from a stooge and getting it on the plane really is a hidden art!

I've got in contact with Tony Hebb and I've printed his entry level 35 out.
So I could be on the way to an indoor event one day...

Thanks for the help along the way

Si
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Skymon
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« Reply #46 on: July 05, 2017, 08:25:31 AM »

I attended my first indoor event last night.

Thanks Ian!

I had a great time. A very friendly bunch of guys were flying.
I had help with pretty much every aspect of flying.
I borrowed all sorts of kit, had rubber donated and lent and I even used some glue to repair my prop bearing.

I learnt a lot!
Trimming wings, incidence, wash in, prop pitch, rubber turns, torque, winding, etc, etc!
All advice freely given in a very friendly manner.

I've spent the morning ordering wood and 'bits' and looking through plans.

Although the ministicks are fun I'm heading for larger territory and I will be attempting to put together one of Tony Hebbs 35cm models.

I'll post my exploits up here for your amusement Smiley

Two important things I learnt - get a bigger kit box with things in it and don't forget the reading glasses!!

Si

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Skymon
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« Reply #47 on: July 24, 2017, 03:10:29 AM »

I've finally made a ministick under the min weight.
The prop was the biggest lump of mass on my plane, thanks to some decent 'indoor' weight wood I managed to get it down in weight.
All of my props so far were approx. 200mg, I got this one down to 130.
Not a massive achievement when there are 200mg EZBs out there, but a nice bit of progress for me.
I fell I have enough ministicks now, with four in the cabinet.
So I'm off on the F1L route now.
I'll be tackling the motor stick first, doing a bit of weighing and tensile testing.
It'll be the classic hobby shopper.


Best regards
S
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