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Old Jan 12, 2003, 12:37 PM
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Cincinnati, Ohio USA
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Slow Stick First flight Results - Where should the CG Be?

I just returned from the first maiden flight of my Slowstick. I had a pretty Meager flight of like 5-7 Minutes with my 8x720 8-Cell AAA Nimh Pack, the BEC kept cutting the motor out! I thought some thing was wrong with the pack or the ESC but the Pack was dead, I guess I have been spoiled by my Lithium Packs!
Anyway, this plane has a tendency to nose up or porpoise, probably due to the climb rate at full throttle. Where exactly should the CG Be? I made a little mark where the instructions indicated it should be but it seems a little tail heavy or maybe it just the nose up tendency that the plane has when throttle is applied. How do I get this thing to fly level for me without climbing, elevator trimming?

P.S. - I have just constructed a Qualcomm Parallel Pack (4 Cells), I'll let you know how it goes. I am getting very interested in these Kokam 1020's that everybody talks about, I may have to check them out.

-Mike-
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Old Jan 12, 2003, 12:43 PM
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I'm tempted to use one of my Radio Shack 1600 Ma 8-Cell Nimh Packs that I use in my Sky Scooter, can it handle the 7.6 OZ of weight that that pack has? Or is this too heavy? I also have one discontinued Radio Shack 1100 Mah Nimh 8-Cell Pack, it only weighs 6.2 OZ. I wish i had more of the 1100's, it's the Ideal battery in my Sky Scooter.

-Mike-
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Old Jan 12, 2003, 01:07 PM
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Forney, TX
Joined Mar 2002
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Mike- I set my CG at the rear mark (105 mm from leading edge). I also pushed the wing back to the rear mark (5-1/2" from front of tube). It flies great with the elevator dead level to the horiz stab. Because there's no thrust line correction in the motor, you're always going to have a little nose-up tendency under full throttle.

==I have just constructed a Qualcomm Parallel Pack (4 Cells), I'll let you know how it goes. ==

I just tested mine on 2x2 cell 1020 Kokams. It draws 8.3 amps at WOT. The Kokams can handle that just fine, but it may be pushing the Qualcomms just a little bit. If you can keep full throttle to short bursts, the QCs should be OK. I'll be flight testing the Kokams when the weather improves. I'm expecting close to 30 minutes flight time.

==I am getting very interested in these Kokam 1020's that everybody talks about, I may have to check them out.==

I flew hundreds of flights on Qualcomms. I tried out the 1020 Kokams when they first came out.... and I've never used my QCs since! They're lighter with more capacity and can deliver higher amp draws than the QCs. You can't beat the super-cheap price on surplus Qualcomms though.

Mike-
==can it handle the 7.6 OZ of weight that that pack has? Or is this too heavy==

I'm sure it can handle it. The wing loading is really low on the SS, it can haul up plenty of extra weight.
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Old Jan 12, 2003, 01:17 PM
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Ah, grasshopper. the CG, as per my SS instructions, should be 95-105 mm from the leading edge of the wing. If you want the SS t otrack straight under poer, then you need 3 degrees down and 3 degrees right pitch on the motor. I usually have my models a little nose heavy, but when I moved the cg back, man! Did she ever float! So, either build a angled stick for it, or just do like me, automatically compensate for it. No big deal.

what kind of BEC are you using? the GWS 100 is rated at 5a, but may guys say it'll do 8-10a no prob. I don't want mine currting out. I'd use the GWS400, since it handles 15a/25a, and you won't have those problems like the other guys do, because, trust me on this, you're gonna be using that small esc, and comes the time you're gonna need it, it'll crap out on ya, and you risk the whole plane.
I'm sure there are guys saying "so what? It's only 30 bucks" but the point is not to lose anything. Penny wise and pound foolish.
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Old Jan 12, 2003, 01:37 PM
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Are the Kokam Packs 2-Cell like the Qualcomm's or one cell? On the BPP web site, he's listing a price of like $8.95 Ea, is that for 1-cell or 2-cells? Would a 3-cell 1020 Pack power a Slowstick (K1020-3s)?
I have several 2-cell Qualcomm packs made up (With Prot circuit on packs). Can I just shrink wrap 2 of these packs together & run a Y-connector to get a "Parallel" configuration & thus the 1660 Mah?

-Thanks-

Mike
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Old Jan 12, 2003, 05:49 PM
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Wexford, PA
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Mike, I fly mine on the Radio Shack 1600 Mah 8 cell NMHI Packs and carry the Aiptex Pencam. The weight the Slow Stick will carry is amazing. It actually seems to help with stability in the wind.

Jim
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Old Jan 12, 2003, 06:05 PM
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Orlando, FL
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One thing that I have found is if you hang the motor under the tube instead of it being on top the tendency to pitch up is reduced.

Rob
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Old Jan 12, 2003, 06:10 PM
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Forney, TX
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==Are the Kokam Packs 2-Cell like the Qualcomm's or one cell? ==

The Kokams are sold as individual cells right now, not in packs. A 2 cell pack wired in series is approximately equal in voltage to a 8 cell NiMH pack. The 2 cell Qualcomms are closer to a 7 cell pack. Some higher voltage applications require 3 cells. As I mentioned, I'm using 2x2 cell 1020 Kokams on my SS. That's 2 packs of 2 cell 1020 Kokams wired together in parallel for a capacity of 2040.

==On the BPP web site, he's listing a price of like $8.95 Ea, is that for 1-cell or 2-cells?==

All his prices are for one cell. Troy will make up the packs for you, but he doesn't have that service listed on his site. You can contact him directly if interested.

==Would a 3-cell 1020 Pack power a Slowstick (K1020-3s)?==

A 1020 pack shouldn't be subjected to more than a 5 amp draw regardless of whether it's a 2 cell pack or 3 cell. That's why I'm running 2 packs in parallel, they can handle more amps than a single pack. The motor draws 8.2 amps at full throttle. You could run a 3 cell 2070 pack, or 2x3 cell 1020 packs in parallel. But if you used full throttle much, it would probably greatly reduce the motor life.

==I have several 2-cell Qualcomm packs made up (With Prot circuit on packs). Can I just shrink wrap 2 of these packs together & run a Y-connector to get a "Parallel" configuration & thus the 1660 Mah? ==

No need to shrink them together, leave them as separate packs so you can still charge them. Otherwise what you mentioned will work fine. But go easy on full throttle usage until you can determine if the packs can handle the amps.
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Old Jan 12, 2003, 10:37 PM
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Tres:
Should I leave the Prot Circuit board on the 2-Cell Qualcomm packs or remove them? If I leave them on & just use 2 packs in parallel with a Y-connector, will that make the prot circuit trip into a shutoff? I tried use a single 2-Cell Pack on a ground test & it tripped immediately. I have 4 packs of the Qualcomm left out of the (10) I bought, I guess I will go ahead & make up the rest as 2-cell pack & (1) Split pack for the Moth.

-Mike-

P.S. - Jim: how does the Slowstick handle with the Radio Shack 1600 Mah Pack? I sure wish they still had the 1100 Mah Packs, I like those better in my Sky Scooter because they are like 3 OZ lighter but sounds like the Slowstick won't care?
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Old Jan 12, 2003, 11:34 PM
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Forney, TX
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Mike-

I just tested a pair of Qualcomm packs in parallel on my Slow Stick and posted the Whattmeter data here:

Surprise gift, why it's a Slow Stick!

Look near the bottom of the thread. Data is quite encouraging, looks like 2 packs will work just fine and in fact will give as much power as 8x720 NiMH. But with longer run times of course. I'd guess run times should be 20 minutes or better.

==Should I leave the Prot Circuit board on the 2-Cell Qualcomm packs or remove them? ==

My packs all have them in place, but I soldered the leads to the B+/B- nodes so that the circuits are bypassed for flying. The motor draws 6.8 amps at WOT from the QCs, or 3.4 amps per pack. You might trip the circuits, I suggest either soldering to the alternate nodes or go easy on the throttle! If you look at the top of the circuit board, you'll see 2 nodes that are clearly labeled B+ and B-. If you solder your battery lead to those, you will fly directly off the batteries but will still charge through the circuits. It's the best of both worlds.

==I tried use a single 2-Cell Pack on a ground test & it tripped immediately==

The motor draws far too many amps for a single pack. I'm not surprised it tripped. I believe they trip somewhere in the neighborhood of 3 to 3.5 amps.

==I guess I will go ahead & make up the rest as 2-cell pack & (1) Split pack for the Moth. ==

I don't follow what you mean, are you splitting the 2 cells apart for the Moth? I used to fly a 2 cell pack on my Moth, I just used my Dremel to hog out some foam from under the nose so the pack would fit.

I just want to make sure you're clear on the difference between parallel and series before you try this. The 2 cells within the pack are wired in series, but you want to wire the jumper such that the 2 packs are in parallel. If you should wire the jumper so the packs are in series, you'd be pumping way too much voltage into the motor. Let me know if you have any questions about that.
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Last edited by Tres Wright; Jan 12, 2003 at 11:38 PM.
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Old Jan 13, 2003, 07:02 PM
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Tres:
The Split Lith works great in the Tiger Moth & you don't have to do anything to the Battery Bay (No Foam Hacking). Just take the 2-Cell qualcomm Pack & just Unsolder the board from one of the cells & just (Bend) fold the cell over to form one "Long" 2-cell battery. Now just run a wire from the bottom back up to the Prot board, then just shrink wrap it & you're done.
Yes, I understand the difference between Parallel & Series. I have just constructed a "Parallel" pack per some instructions I found on the Ezone. I will be trying it out hopefully this weekend, I do that pretty much the same way, I have a Prot board between the Charger & the pack but when I fly there is no Prot board used.

-Thanks-

Mike
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Old Jan 13, 2003, 09:24 PM
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Wexford, PA
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Mike, I can't really say how it handles compared to other batteries, I've only flown it with the RS 1600's. And only carrying the camera. I have only had it for about a month and the weather hasn't been very good so I don't have all that many flights on it. And those were just tooling around taking pictures -- handles fine for that. I got it just to carry the Pencam (had the Pencam on the Sky Scooter before that). I've got some 8 cell 700 mah NMHI AAA Maxell packs I use in the SwitchBack 3D and UrbanFlyer I will probably try when the weather gets better. For now it's doing what I need on the RS packs, but I don't know how long the motor will last on them.

Jim
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Old Jan 14, 2003, 10:42 PM
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Wayne's World - Illinois
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What qualcoms are you guys using? I just took two packs from our old 2035a kyocera cell phones...I don't know the model munber of the battery, but according to what I was told, they're 900mah packs. Will these work for a decent pack? Have an SS on order,...didn't want to see you guys having all the fun. That and I'm getting alittle tired of building at the moment...want a done plane.

What mods are being done to the SS for improvements...or does "being taken out of the box and flown" suffice?!
I hear a few different prop sizes being said, new motors being put in, 7-8-9 cell nimh packs, twin wings, twin motors, twin wings "and" motors and saw boomerace's great idea of using the northeast sail planes light weight wheels{those the big or small ones Boom?}...what of these would I be looking for...for a long term flying, easy maint SS?
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Old Jan 14, 2003, 11:19 PM
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Phoenix, AZ
Joined Jan 2003
100 Posts
I'm running mine with the bydusa.com 7 cell 1100 mah NIMHs with the CG slightly forward from 105 mm recommendation in the instructions. I also hand bent my stick down and to the right to get some down thrush and it doesn't porpoise. Flies really nice actually. Hands off with about 1/2 throttle and it flies nice and straight. I'm also using a 12x6 prop instead of the stock 11x8.
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Old Jan 15, 2003, 01:38 PM
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Cincinnati, Ohio USA
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I tried using an 8-Cell AAA 800 Mah Nimh Pack & was very disappointed, short flight. Imho, go for the Qualcomm Lions or the Kokam Lipoys. I just made up & charged a 4-cell Qualcomm Parallel Pack, just waiting for the weather to improve.
I noticed a lot of porpoising when I did my first "Shakedown flight of my stick, I need to do something because it was not fun! I will try moving the CG forward a little & maybe bending the stick mod as well.

-Mike-
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