It is with great humility that I present the next installment. Here are the previous;

Part V
https://www.rcgroups.com/forums/showthread.php?t=241284

Part IV
https://www.rcgroups.com/forums/show...9&page=1&pp=15

Part III
https://www.rcgroups.com/forums/show...5&page=1&pp=15

Part II
https://www.rcgroups.com/forums/show...5&pagenumber=1

Part I
https://www.rcgroups.com/forums/show...9&page=1&pp=15

You can't stop a good thing going

Aloha Ken,
Glad to hear of your successful flights. 42 minutes on 2 packs is excellent time. You want to be sure you have a collett style prop adapter. The set screw style adapters....suck. That 6x4 prop should work well, the smaller 5.5 prop may give you a little more speed...maybe...but you will have less torque(climbing authority). You can run a 10 or a 12 cell pack, with a 7x4 prop and have unlimited vertical. That's always fun!! Hope this helps.
Lono

Hey thanks Lono,


I was thinking of using this prop adapter...
MJ4702 - COLLET PROP ADAPTER 3.2MM, M5 From hobby Lobby...

I'm currently using a set screw adapter and Im not impressed as the prop doesn't get sandwiched...

Yes, I guess I could up the cells, but a 9 cell is enough for me to handle in my learning stage. Plus, its just that much more weight.. And it will again effect the CG, Yuck. I guess everyone adds 2 or so ounces of lead to the front??? The Winglets were rebuilt and installed last nite and molded some lead fishing weights using a torch and hammer!!

I had a fun time flying the wing.. Really fun. I just wish it hadn't been so windy.. Oh.. Now I know what a tip stall is Evil.

Anyone care to explain the difference between D/R and expo to a newbie?? What should the unicorn be set at for easy of flying?

I set the Throws on the elev, alierons to 60 or 70%.. And set the EXPO for both two 25% as per Up&Aways suggestion...

Ken

Lono,

How do you fit 10 or 12 cells into the uni battery bay?

I can barely fit the 9 cell in a flat config? Do you modify the bay to take the cells four wide? If so this may certainly help my CG issues, by moving more of the battery weight forward.

OK, I'm to the part where I need to test all the electricals. Do I need to slow charge the stock battery, NiMH KAN 1300 mAH 8 cells, the first time I charge it. If so can I do this on a PIRANAH Digital Peak charger or do I have to use a wall wart overnite. The PIRANAH is adjustable from 0.1 to 5.0 amps but haven't used it yet as I haven't been at this long and have slow charged my plane batteries on the wall wart up until now. Someone told me you don't have to slow charge NiMH the first time like you do nicads.

Thanks to all for the info you have provided on your brushless corns I am using the info as part of the background work for a new cell on the block I have done half of the static tests (using nicad cells) now to compare with the new battery pack. When all the data is in I will post the results.I hope the new cells will be able to give a corn running on approx. 12v the duration of a lithium pack with the safety of the nickel metal hydride cells

the results will be ready as soon as possable but the flight tests will be delaed by the werid weather the UK is getting at the moment

Klong66,
GP 1100 or kan 1050s

----
---- nose of wing here
----
.......................3 end to end sticks of 4 cells each
Lono

Dynofly,
Yes, you should slow charge your NiMH pack for the first charge. I'm not familiar with the piranah charger, but you mentioned that it's adjustable from 0.1 up to 5.0 amps, so if that is correct then yes, it will work. Charge your pack for the first time at 0.1 amps (lowest setting) for 16 hours. What this does is it allows the individual cells to reach a sort of voltage equallibrium (balance) with each other and stabilizes the pack as a unit for future rapid charge/discharge cycles. Down the road, if your pack just feels like it doesn't have the "oomph" it used to, repeat this procedure. Or if you ever have to change out an individual cell, you'll want to balance the pack again.

Ken,
Dual rates basically give you two completely different travel rates of a servos travel for greater versatility in controlling your aircraft. By programming the second set of servo travel volume at a lower rate than normal, you can get a feel for your bird, set trim etc. without it being nearly so sensitive to stick input. Then flip the switches to high rates to really rock and roll. I stayed on low rates for the first few flights, and then slowly increased them as I gained skill as a pilot (which , by the way, I'm still doing lol).
Exponential allows you to change the control response of the sticks from being a linear response to what is called an increasing response curve, or exponential. With this activated, you'll have very little servo response when the sticks are near center or neutral. As the sticks are moved farther from the neutral point, more servo response is generated at a rate greater than a straight linear response, allowing for extremely quick and precise maneuvering. This feature is more applicable to 3D flying and since most novices tend to over control their models, I personally have found that using expo can get you into trouble alot quicker than you can get out of it, if you don't know exactly what you are doing.
I like to set new unicorns at 60% dual rates for channels 1 and 2. NO EXPONENTIAL. (which I did today...pics soon).
Hope this helps.
Aloha,
Lono

Thinking of using LiPo's in my 'Corn - have been content with 1050 8 cell KANs - but feel the need to move on.
What LiPo's are people using in the UK and where are they from?

How do you guys think a 10C Li-Poly 1800mAh 3S PACK (11.1V, 18.0A) would go with a Mega1615/4 and Phoenix35? And a 6x4APC prop.

Originally Posted by Up&Away

How do you guys think a 10C Li-Poly 1800mAh 3S PACK (11.1V, 18.0A) would go with a Mega1615/4 and Phoenix35? And a 6x4APC prop.

My 16/15/4 with APC 6 x 4 measures about 23 amps at static WOT on an Astro Whattmeter. Even with a 15% drop in the air when the prop unloads, that is still 19.5 amps at WOT.

A 10C 1800 mAh cell can only produce 18 amps continuous and 21.6 amps burst. That means at WOT you will be over the limit for a singe 3S pack. and lipos are very intolerant of overcurrent situations. "Can you say expensive silver sausage?"

You really need a 3S2P configuration or larger capacity cells, like 2600 mAh. Unfortunately, the only 2600 single cells I am aware of are the Irate from Cheapbatterypacks.com, and they are an 8C cell, so you would still be under the WOT draw

If you do go 3S2P, be aware of the problem with cooling. Lipos also have a lower temperature threshold than do NiMH and NiCD cells, so the 3S2P packs would need to be side-by-side, not one pack on top of the other. I tried the over-and-under set up with 6C cells, six cells deep, and the bottom cell got waaaaay too hot. Two Thunder Power 3S 10C packs would work with just a little widening of the battery bay, since the TP 1900 and 2100 packs are very narrow. TP seems to be out of stock on everything right now.

No mater what you do, it will be $$$$$$$$$

FoamCrusher

Thanks Foamcrusher! I'll go for the 2600 3S then. I am re-doing my 'Corn. One of the mods I'm planning is a coroplast battery cover with an airscoop. Temperature should be ok.

Originally Posted by Up&Away

Thanks Foamcrusher! I'll go for the 2600 3S then. I am re-doing my 'Corn. One of the mods I'm planning is a coroplast battery cover with an air scoop. Temperature should be ok.

The scoop sounds good. How about some pix when you are done with it?

BTW, if I were spending your money, I would go with the Thunder Power Gen2 2100's. They will pull 10C continuous (21 amps) and in parallel in a side-by-side configuration, will give you 4200 mAh - enough to practically fly all day . The pack would be about $160 USD though

FC

Originally Posted by Up&Away

How do you guys think a 10C Li-Poly 1800mAh 3S PACK (11.1V, 18.0A) would go with a Mega1615/4 and Phoenix35? And a 6x4APC prop.

I did a rough analysis on motocalc as this is close to my setup (except I’ve got a 16-15-3).

>>> Health warning: I might have messed this up.

I've estimated config values for the Lipo pack. given this, Motocalc says that you still might need more current to power this setup (which might draw about 25A). The 2000mAh 15C 3s kokam packs would give around 30A and this would give you some margin. This is the pack I use and it's ballistic.

EDIT: note that I posted an earlier version with (very) wrong Lipo config parameters. Think this version is better.

Cheers.