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How much battery have you stuffed in an FT Explorer?

evranch

Active member
#1
As my Explorer is coming up to the finish line here, I realize I have no mid-sized batteries for this plane. It doesn't look this big in the pictures! I go from the 300mAh range for gliders, to the 1500mAh range for parkflyer sized planes, then I jump way up to 6000 and even 8000mAh for big UAV work. All 3s except for some smaller 1s and 2s cells for unpowered gliders.

Everyone says their Explorer is tail heavy, so how does that 6000 mAh 3s sound up there in the nose? Too much? I can always maiden with something in the 1000-1500 range but I suspect my flight time will suffer and my plane will be tail heavy.
 
#2
Use what ever gets it to balance. I have 3 18650 li-ion cells taped together as far forward as I can get it because my biggest battery(only have 2) is a 3s 1300. It doesnt matter what you use. As long as it balances
 
#6
I typically fly mine with a 2800. I imagine that it would still fly with the 6000, but I definitely wouldn't try it without a reinforced spar as others have mentioned.
 

evranch

Active member
#7
Finished the plane! The 6000 (actually a 6400) just fits inside the fuselage. Balance point is halfway in, halfway out of the nose tray. The 1500 is hopelessly lightweight even with the boom pushed in as far as the hole for the servo wire will allow.

I will probably maiden with the 1500 and some dummy weight. I would say my FPV gear will add weight, but it's a wolfwhoop cam and a 500mAh 1s, so we're talking about under 50 grams.

The airframe weighs 540g and the 6400 mAh battery weighs 450g. So it will almost double the wing loading from empty, and at the very least my stall speed will be significantly increased.

I built the wing without any metal or fiber spar, but it doesn't have the cut for dihedral and the center foam spar is wrapped in fiber tape, and the two wing halves are fiber taped together. It should be a little stronger than stock, but if I had planned for this heavy battery I would have thrown an old arrow through the wing for sure.
 

kilroy07

Well-known member
#8
I fly mine (rather flew) with a pair of 2200 3s. Once I added some FPV gear in the nose and pushed the boom in it would balance with a single 2200. Might look into getting a couple 2200 batteries, they work for a majority of the (larger) FT designs.

<Edit.>
I almost forgot, with the pair of 2200, I broke a wing as others have stated...
Use something to reinforce that spar! Especially if you run the 6000.
 

evranch

Active member
#9
Well, I have it balanced for the maiden with a 1300mAh 3s, the 500mAh 1s for the camera (camera not installed for maiden) and a pair of dead AAs strapped under the tray. I questioned the sliding boom at first but it's really a great feature being able to use it to fine-tune the CG without moving any weight. It's currently near the "stock" position where the holes are mostly lined up.

The cam mount was the easiest thing to build, just cut a little tab out of the nose below the vent, flipped it up, cut a slot for the narrow part of the lens to press-fit in, glued the tab up so it wouldn't move, and done. Hope the weather is decent tomorrow to take it up and that it survives the maiden, I'm excited to try it FPV.

Anyone have any ideas on how to reinforce the wing without tearing it apart? I built it pretty sturdy, so it's probably going to be easier just to build a new wing rather than tear it apart.
 

Headbang

Well-known member
#10
I found mine was a little light and ended up flying tail heavy on the maiden with a 3s 2200. It was perfect with a 3s 3000, the extra wieght helped over all stability as well. Photo001 lengthened the nose to give room for a 2200 to balance.
Strip of packing tape the length of the wing o the bottom goes a long way to stiffen it.
 

evranch

Active member
#11
Strip of packing tape the length of the wing o the bottom goes a long way to stiffen it.
By length, do you mean tip-tip or fore-aft? Mine is already fully tape-wrapped with fiber tape around the joint fore-aft. I can see how a length of tape from tip-tip could also act as a sort of tension wire though, to keep it from bowing upwards.

I noticed that even though I built the wing without any dihedral, the wingtips are a bit higher than the center. Maybe something shrinks in the gluing? It appears to be symmetrical.
 

Headbang

Well-known member
#12
By length, do you mean tip-tip or fore-aft? Mine is already fully tape-wrapped with fiber tape around the joint fore-aft. I can see how a length of tape from tip-tip could also act as a sort of tension wire though, to keep it from bowing upwards.

I noticed that even though I built the wing without any dihedral, the wingtips are a bit higher than the center. Maybe something shrinks in the gluing? It appears to be symmetrical.
Tip to tip, it takes a large amount of the flex out of the wing. I did it on top and bottom of mine, I tend to do a lot of inverted maneuvers like outside loops.
 

evranch

Active member
#13
Sounds great, if you can pull negative Gs without bending or breaking the wing then you must be doing something right! I will run a strip of fiber tape and then cover it with the much stickier and UV resistant repair tape.

I don't plan on taking this thing through much aerobatics anyways, it's going to be my tame FPV trainer. With some reinforcement I can probably fly the 6400mAh as long as I treat it like it is an airplane and not a toy. I learned awhile ago that it's easy to lawn-dart the fuselage and watch the wing come down slowly on larger, heavier airframes.

Next time I'm in the city I'll have to look into some medium sized batteries, 2200 or 3000 for some of these larger FT planes. I'm sure I'll be building more.
 

Chuppster

Well-known member
#14
I fly mine (rather flew) with a pair of 2200 3s. Once I added some FPV gear in the nose and pushed the boom in it would balance with a single 2200. Might look into getting a couple 2200 batteries, they work for a majority of the (larger) FT designs.

<Edit.>
I almost forgot, with the pair of 2200, I broke a wing as others have stated...
Use something to reinforce that spar! Especially if you run the 6000.
Mine broke where the servos mount. You NEED a wing spar for this airplane.