building a glider
- Thread starter hello183
- Start date
Thank you @danskis. I'd like to finish this, then maybe sometime later, I may design something better. I may try to add some form of a dethermalizer, but I don't really think I will be able to launch it so high that any thermal can take it away. But I still do have to cover the wing before it's done. I actually used a method similar to what both of you said to align the stabilizer.
I glued on the vertical stabilizer today. I made sure to get it perpendicular to the horizontal stabilizer and parallel to the stick it mounted on, yet when I looked at it it still looked as if it deflected a little bit more to one side. I hope it isn't too big of a problem because I could adjust the trim tab for that when I fly the airplane.
Before I can cover the wing, I have to sand it, and it is really difficult. I have been trying to use the xacto blade and cutting off material before I sand. it is working fine now, but if I do this again I might pre-shape the leading and trailing edges. It is hard to get the angle right without the sandpaper touching the rib. I have tried to use masking tape, but the sandpaper kind of pulls the tape away.
CthulhuJon
Member
did you finish or fly it yet ?
I haven't really finished it yet. I am still working on sanding the wing. But I'm almost done with the leading edge, and I finished the trailing edge. But I have also been filling some parts of the ribs with scrap balsa to get the shape better. After that, I still have to finish and paint the nose cone. So not yet. Do you know any fillers that can be used on foam and balsa?
Also, this is unrelated, but have you guys used those 18650 lithium-ion laptop batteries on anything? What current motor have you been able to get one to handle? I soldered 2 together in series for a 60-amp esc, and it goes into low voltage protection even when the batteries are fully charged when the throttle is on. They were used cells, so could it be those cells with the problem specifically or are they not really able to handle being used at 60 amps?
quorneng
Master member
hello183
There are 18650 cells and there are 18650 cells!
Top quality ones can handle a reasonable number of amps but never 60! Even the best from major manufacturers like Samsung and Sony can only manage 25A max but are correspondingly expensive. Cheap 18650 as found on Ebay are likely to drop their voltage at just a few amps.
Some time ago I built this plane that uses 18650 cells.
Four individual cells held inside the wing spar in a 2s2p configuration so they deliver 7.4V.
The cells were very cheap but with a small motor it only needed a total of 6A. Even so the cells had nothing like their marked 3000 mAh capacity, actually less than 1000! so were pretty heavy relative to a LiPo for the power they delivered.
Be aware that laptop cells are required to deliver their full capacity not high amps, in fact less than 3 amps continuous.
There are 18650 cells and there are 18650 cells!
Top quality ones can handle a reasonable number of amps but never 60! Even the best from major manufacturers like Samsung and Sony can only manage 25A max but are correspondingly expensive. Cheap 18650 as found on Ebay are likely to drop their voltage at just a few amps.
Some time ago I built this plane that uses 18650 cells.
Four individual cells held inside the wing spar in a 2s2p configuration so they deliver 7.4V.
The cells were very cheap but with a small motor it only needed a total of 6A. Even so the cells had nothing like their marked 3000 mAh capacity, actually less than 1000! so were pretty heavy relative to a LiPo for the power they delivered.
Be aware that laptop cells are required to deliver their full capacity not high amps, in fact less than 3 amps continuous.
CthulhuJon
Member
lots of options I think... try light weight spackling from hardware store...
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I have finished sanding the leading and trailing edges. I glued these 1/16 sq sticks between the center ribs to give the covering more support for the rubber band. @CthulhuJon Thanks for sending me this. I will look for the lightweight spackle at the hardware store. I just want to fill up some ribs for this with scrap balsa, then I will go to covering.
@quorneng, my dad suggested I would need at least 6 of the 18650 cells, which would be 3 groups wired in parallel of two batteries wired in series. It would weigh 3x what it did before, but this is not for an airplane, so weight does not matter too much. Are there any suggestions about this? Should I just get a lipo battery for it?
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quorneng
Master member
hello183
The choice of battery all comes down to weight and performance.
A LiPo has about the highest rate of discharge for its weight of any battery which is why they are used in model planes.
An 18650 cell will likely last a bit longer if you can do without a 'sprint' capability. They are after all used in road cars where a long life and the ability to be recharged several hundred of times are important characteristics.
The choice of battery all comes down to weight and performance.
A LiPo has about the highest rate of discharge for its weight of any battery which is why they are used in model planes.
An 18650 cell will likely last a bit longer if you can do without a 'sprint' capability. They are after all used in road cars where a long life and the ability to be recharged several hundred of times are important characteristics.
danskis
Master member
Here's something to chew on in your spare time
https://batteryuniversity.com/article/bu-205-types-of-lithium-ion
And yes get a Lipo if you can afford it
https://batteryuniversity.com/article/bu-205-types-of-lithium-ion
And yes get a Lipo if you can afford it
CthulhuJon
Member
You can get 1s and 2s lipo batteries cheap, if you buy the ones that are for toy/drone replacements, often that come with a mii USB charging circuit like this, so you can avoid buying a $50+ charger... https://www.amazon.com/gp/product/B094FQFRFM/?tag=lstir-20
you'll need to choose one with capacity to match your motor glider though.
..eventually worth getting a proper charger though.
you'll need to choose one with capacity to match your motor glider though.
..eventually worth getting a proper charger though.
I accidentally made a mistake and tore the tissue, so I removed the covering from the wings and tried a different method. It seems smarter for me to cover the entire bottom first to make the overlaps tidier. What is the biggest wing anyone has used sliced or stick built ribs for? I am curious about how strong that building method is.
