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Author Topic: Ministick and microstick - trying to get back into indoor!  (Read 20193 times)
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Flyguy
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« Reply #75 on: November 07, 2015, 01:44:55 PM »

I thought this would be in the Coslick article, which I know you have, however now that I look at it, he doesn't seem to mention it, which is kind of odd, unless I missed it. In any case, assemble the complete plane except for the wing and put a loose motor on. Then wrap a thread around the motorstick and move it back and forth until it hangs horizontally, that's the CG.

The usual approach is to then locate the rear post as a percentage of the wing chord. For example, if the wing chord is 3", then the rear post is located .6" behind the CG so that 2.4" (80%) is in front of the CG. If you do it the CMOS way, as on the plan, then you locate it as I explained above. I hope this helps, you should be getting close to flying!
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Jimmy JFlyer
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« Reply #76 on: November 07, 2015, 02:12:01 PM »

ah that helps a lot Larry. Thx!
Well..... I didn't work on the micro stick last night as planned. I ended up having a good week and bought a Guillows Lancer and couldn't resist working on that instead.

But I want to get back to the micro stick as now I have clarity thx to your explanation of doing CG. With the incoming weather it's the micro i'll be flying more anyways so I need to get back to it. I just love building and with the Lancer I knew I could build more than research and with only about 2 hours I wanted to build instead of read.  Grin

Your explanation of getting CG makes total sense. I should be able to get to the finish line from here without much trouble. Can't wait to fly this little guy!
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fitnezz
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« Reply #77 on: November 08, 2015, 04:54:03 AM »

Great models and topic, a lot of valuable informations here Smiley

I have a feeling its a good place to ask following question I have. It is about the angle of the propeller blade on the forming jar.
I see on the plan: 17deg. On diferent plans for diferent or even same diameters I see diferent values. Like it does not matter that much if it is 15 or 20.
So I am a bit confused since the diference in that angle obviously would give diferent prop pitch for the same pitch gauge setting.
I would expect for the 5" prop on the 3" jar degree to be bigger. The chart I was using says it should be about 26deg for the 3" jar. I attach the picture with diagram.
What is the correct way of calculating this angle?
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frash
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« Reply #78 on: November 08, 2015, 10:44:13 AM »

Fitness,

Look in the Builders' Plan Gallery/Airfoils and Propellers for "Bucket Props". One or the other of these two Excel spreadsheets might help. If the camber of the blade seems excessive, try a larger diameter conical cup. A bucket obviously is too large for a Ministick prop. A coffee or yogurt cup might work well as a form. I've done several  Ministick props. A conical form is a little better than a cylinder, but a cylinder can also be used if nothing better is found.

Fred Rash
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fitnezz
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« Reply #79 on: November 09, 2015, 04:34:51 AM »

Frash,

Thanks I saw theese before. I always use what is on the plan for the given blade and always use 3" jar as the form. This microstick from that post has prop 5 dia and 17 deg slant on 3" jar. Author of this post mentioned different props he tests with P/D 1.6 to 2.3 (afair). I just wonder if using this 17 degree twist those P/D are not way smaller than author expects. ( hope not Smiley )
« Last Edit: November 09, 2015, 05:27:40 AM by fitnezz » Logged

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Flyguy
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« Reply #80 on: November 11, 2015, 04:15:57 PM »

You're right, thanks for catching that! When I made the plan, I just stuck in the angle that I was using for my EZB props decades ago and figured that I'd make the correct calculation later, but then forgot about it. Ron Williams gives the formula in the appendix of his book, I just tried a quick calculation and for a 5" prop with 9" pitch it comes out to 31 degrees, close to the 26 you got from the chart, so that sounds about right (Ron points out some limitations to the approach). The angle also changes as the pitch changes.
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fitnezz
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« Reply #81 on: November 11, 2015, 06:37:50 PM »

Great, thanks for the answer and the formula source. Good to know, that this chart gives kind of correct angles values  Smiley


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Jimmy JFlyer
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« Reply #82 on: November 13, 2015, 11:40:08 PM »

Larry,
I have the mentioned .008 wire for the shaft and rear hook. I also have the little IMS bearings from A2Z. The ones that come as a 6 pack. The .008 wire is still too big to fit in the frt hole and rr slot. Did you open them up somehow? I can't imagine doing that with anything but a micro drill bit which I do not have. Now I have the bigger Harlan style bearings I used for my LPP that will fit but they are probably 4x's as heavy and so much bigger.

Any advice? Is there wire thinner than .008? I am thinking not. At least my research on guitar strings hasn't found any.

I suppose I could always just bend my own. Just didn't want to if not necessary. The IMS bearings are so sweet.

Regards,
Jimmy
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Flyguy
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« Reply #83 on: November 14, 2015, 11:33:28 AM »

Something isn't right, if I remember correctly the A2Z bearings take up to .015" wire, and as mentioned earlier in the thread, I ended up using .01" wire. So your wire must not be .008" or it would easily fit in the bearing.
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Jimmy JFlyer
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« Reply #84 on: November 14, 2015, 11:45:31 AM »

Ya know, it has been almost 2 years since I started on this and now that I think about it, I may have never even gotten the .008 yet. I bought some but now that I crunch my tired and forgetful brain I only bought guitar string from the local music shop once, and that was .015. Yes you are correct. It is probably that .015 I was trying. I think I intended on getting the .008 and never did. I just needed you to help me jog my memory. lol

Now I am back to excited again.  Grin

Just to show how long it has been and how much I have forgotten, I was all excited last night to get some time to work on this guy. I made the boom and motor stick and started looking into bending the bearing & get it mounted and that's when I started looking at the bearings I have and my available wire. Then when I was cleaning everything up I saw in the bottom of my box the motor stick that I had already made almost 2 years ago complete with properly bent bearing already glued in place.  Embarrassed

Looks like I am headed to the music shop today.  Wink
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fitnezz
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« Reply #85 on: March 13, 2016, 07:32:32 PM »

You guys complain about flying space. Still you dont know how tough it gets sometimes Wink

This post is cool. Inspired me to do 5 inches airplanes to fly around.
I made small vid how I do it. It could help someone starting up.

https://www.youtube.com/watch?v=xGmP43LpLGk

6 inches work better for me, with 5" I dont get 3 minutes, but close to. 6" does above 4, when the good wind blows Wink

https://www.youtube.com/watch?v=IggsJ_GMgN8

No indoor materials used btw. Covering with super slim sandwich bags. My lightest micro -> 0.33g.

best regards

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Flyguy
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« Reply #86 on: December 19, 2017, 07:07:54 PM »

Well, just to summarize this thread, unfortunately my attempt to get back into indoor flying nearly 4 years ago was a complete failure (been doing a lot of outdoor flying though). I flew in various spaces in the University where I work for a few months, but without a regular 'real' flying space, where you can land without hitting desks, one inevitably loses interest. I want to see the torque, winds, height, flight time, etc. and need a real flying space for that. So no indoor attempts since 2014, and no real indoor flying since Columbia 1992.  Sad

However, I recently found out that there is indoor flying in Teaneck Armory, and more important, there are regular buses from Port Authority that go there! I can walk to PA from my apartment. So I'm excited about going there tomorrow. I have two ministicks that have been sitting around, and 2 micro sticks ready to go. Last week I thought I'd try my hand again at some indoor building since there's been none since 2014. I made a new shop recently, so everything was packed and it took me a few days to find some stuff. So I made a new ministick, same as the previous but different elliptical stab, pictures below. This is the first time I've tried OS film and I really like it, easy to handle plus it cuts really easy, just kind of melts away from the hot pen, whereas the Mylar took more heat. Really nice stuff.

My last mini was 0.43 g on the nose but this one came out a little light at 0.394 grams, I'm sure because the OS film is really light! Not a problem, I could always add a little weight but I'll wait because with adjustments/repairs it will probably gain a little weight anyway. I have some 7 x 12 and 7 x 13 props, so I made a new 7 dia x 14 pitch prop, tried it in the living room and it was pretty nice, new plane floated around at what seemed to be slower than usual speed, so far so good. Can't wait to give it a shot in the armory. I'll probably be having 90's flashbacks for a while just being in an indoor space, with indoor modelers and airplanes!


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OZPAF
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« Reply #87 on: December 20, 2017, 12:13:53 AM »

Sounds like fun - good luck with that. Indoor certainly has it's charms - I haven't flown seriously(sort of) since the 90's as well. I was flying a EZE B then before any sort of film!(condenser paper).

Merry Christmas
John
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Flyguy
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« Reply #88 on: December 20, 2017, 06:20:13 PM »

OK, did some flying! First up, my 1992 mini. Did over 5'40" (had trouble starting the stopwatch), so that's not too bad first time out. Unfortunately, it ended up in an H-rafter on the next flight, gone for good! My new ministick flew really nice, lighter and lower rpm, but got hung up on the second flight with some minor damage upon retrieval, didn't get any video of it. Finally, initially had some trouble with my 2014 mini, but got it going before calling it a day, also the only video I took (too busy flying). I haven't posted many videos this year, so I put up today's adventure here: https://www.youtube.com/watch?v=DnWYfe5U7PM  Looking forward to some serious trimming the next few sessions!
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« Reply #89 on: December 20, 2017, 09:48:58 PM »

Sounds like fun - good luck with that. Indoor certainly has it's charms - I haven't flown seriously(sort of) since the 90's as well. I was flying a EZE B then before any sort of film!(condenser paper).

Merry Christmas
John
Sorry, with all the excitement forgot to say Merry Christmas to you as well John! I might be doing some quick indoor building over the holidays.
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OZPAF
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« Reply #90 on: December 21, 2017, 05:02:11 PM »

I really enjoyed that Larry. What a site although the trusses are a worry. That's the challenge though - longer lighter motors to keep the climb down and the duration up. I was a little surprised to see that you had to take a 40min bus trip to get there.
Thanks for the video.
Have fun and happy building
John
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Flyguy
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« Reply #91 on: December 21, 2017, 08:20:26 PM »

Thanks John, glad you enjoyed it, I debated putting it up because I didn't get any video of the new mini! It flies slower than the one in the video.

Those trusses are a worry, I lost my first mini inside one, no way to get it back, and my new one ended up on them twice, but it stuck out a little and I was able to get it back with a 50' pole (thanks to Tom and Dave for bringing that!). Though it's a 50' ceiling, so I guess it's Category 2, the trusses start at about 30 feet, so I think you just have to fly it like Category 1; I'm scared of those trusses now! Thanks to all those years flying in Columbia's 100+ foot ceiling, I'm really a high-ceiling flyer, so this low-ceiling stuff will be a learning experience.

Trip out was 40 min because the bus made a lot of local stops, they weren't on the bus schedule so I was a little nervous, but it stops right in front of the armory so you can't miss it. Ride back made fewer stops and was like 25 min. Bus wasn't crowded so I think I''ll bring my 27 year old EzB next time out and maybe build something else small, like a no-cal.
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« Reply #92 on: January 03, 2018, 05:13:36 PM »

Another fun day at Teaneck! First 90 minutes I spent helping a young girl who was given a plane to build for the Science Olympiad, but the school didn't have anyone who knew anything about flying to help her. We had to do some field surgery - cut off and re-do the nose from upthrust (yikes) to downthrust, extend the tail boom as far back as possible, add some turn and slight incidence, tilt the stab, some experimenting with the rubber, and it went from diving into the ground to a nice minute-long flight! She was thrilled once it got going and wanted to continue but had to go to school. My good deed for the day.

Finally got to fly the new ministick, flies nice, and I kept the torque/winds low, but still ended up landing on a heater so it was gone, barely got to fly it! Video'd it and put it in my A6 video. Already have another mini under way.

I just discovered 'A6' which looks really fun so I designed and built one over the weekend, with a nice paddle blade prop! Flew right off the board, I didn't even do anything. Got in two flights, video'd the second one and put it in the A6 video: https://www.youtube.com/watch?v=Tjn5j2WrHlo

I didn't want to risk losing another plane so that was it for the day. I'll make some more A6 props for next weeks romp, I knew this was going to be a fun category!

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« Reply #93 on: January 03, 2018, 05:21:55 PM »

Oops, forgot to post the pics. Weight-wise I was lucky and it came out to exactly 1.2 grams (wing and stab are really light so I left the fuselage a little heavier). Tempted to build another since my loss-rate at Teaneck appears to be one a week!
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« Reply #94 on: January 04, 2018, 06:15:51 PM »

Well that's dicing with death Larry Smiley Very nice trim on your models. The climb on your A6 surprised me - the initial climb rate didn't look that strong. Thermals? Smiley
I guess you will be looking for slightly thinner section rubber now.
Do they ever service the heaters? There must be quite a few models hung up on heaters and the trusses.
Thanks for another enjoyable video.
John
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Flyguy
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« Reply #95 on: January 04, 2018, 08:56:09 PM »

Thanks John, I thought the huge paddle prop would keep it low, and I was happy with the slow climb, but I was a little surprised that it really wanted to keep going up after 30 ft. I don't like flying in the girders so I have to work on keeping them low. You got it - I'm slicing some thinner rubber for next week, the video A6 flight used some old .050 rubber I had, I'm slicing some new .045 and .040 for next week.

I've heard that they clean out the trusses once or twice a year, they throw down dozens (!) of planes and whoever is there can take them, the mini I lost two weeks ago will be in that group - it's inside the I-beam and impossible to get. For last weeks lost mini, the tail was slightly sticking off of the heater, so with the 50' pole available next week I might be able to get it down, though I don't know what kind of shape it will be in after sitting on a heater for a week!
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« Reply #96 on: January 06, 2018, 05:51:19 PM »

This must be a bit annoying when flying indoor. I know when I lose an outdoor FF model - it's ok if it disappears in a thermal but it's outright annoying if it can't be found even when you think you know where it is.
I'm just thinking of losing my favourite CLG recently. I saw it's general direction but it disappeared in a mess of tall (shoulder height) grass and lantana. 4 or so searches were unsuccessful

John
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« Reply #97 on: January 07, 2018, 12:29:57 PM »

It is a little annoying, I've lost two minis in two flight sessions, I hope that pattern doesn't continue, I just made a third mini and if I lose it this week I'll be upset! I'm stripping thinner rubber and making flaring props now, have to get used to this low ceiling stuff.

Outdoor is a little different - I have so many planes at this point that I wouldn't mind losing some to 'thin the herd' a little, my outdoor building has greatly slowed down because I'm running out of storage space! But with RC rudder you just never seem to lose them, I can steer out of even the biggest boomer.
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« Reply #98 on: January 07, 2018, 01:01:08 PM »

Can you tell us what size motors you are using (length and weight) and what torque you are launching at?

Subject to the above information, I suspect you may be heading in the wrong direction by going thinner.  Generally you go thinner for higher ceilings and thicker for lower ceilings.  This is because it is difficult to use the torque above the knee in the torque curve in a low ceiling without climbing into the ceiling.  If you do go thin enough to use that torque your cruise will be very weak.  In a low ceiling site you are trying to minimize climb (just enough to get to the ceiling) and maximize cruise by using the flat part of the torque curve.  This means backing off turns down to the flat part of the curve on a heavier motor that maximizes the cruise time and theoretically the time on the watch.

The above assumes you are trying to maximize the duration and not just put up safe flights and that the prop diameter and pitch (and possibly flare) are matched to the rubber.

Hopefully some others more experienced than me can chime in with their thoughts?

Rey
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« Reply #99 on: January 07, 2018, 07:20:08 PM »

Thanks Rey, that's interesting. Right now I feel like a babe in the woods indoor-wise, it's been decades, I got very good in the old days at getting them up 100 feet with long cruises since it was a high-ceiling site, so this is very different, with rafters waiting to eat my plane at about 40 feet!

Just got started, so I'm just guessing on prop/rubber combos and haven't really gotten into details yet. Only got one flight in with the mini before it hung on the heater (shown in the video). For that I used some old .025 rubber I have, about 14" long, weighs about .45g. I wound it 2500 turns, then backed off about 1000 turns, I think the torque was in the 2.5-3 oz-in range, that seems to get it up about 45 feet. For this week, I have a new prop with more blade area, will try that with the same motor to see what happens.

For the A6, I used some old .050 rubber I have, about 17 1/2" long, weighs 1.12 grams. I think I did the same thing as for the mini - wound it to 2500 then backed off 1000, I have to pay attention to the torque this week, I think it ended up again in the 3-4 oz-in range? Motor seemed kind of big, I was thinking of using this week some .040 I recently stripped, a few inches longer, should give close to the same weight. I'm also making a slightly higher pitch prop to see what that does.

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