FT Mini Arrow

[Mr Man]

Yes I agree, Having built an arrow in the past (and a modified arrow for speed as well) I can say that yours is probably a tad nose heavy

 

[andrej]

Has anyone tried flying with a 3S 18650 pack? So that it can fly for 3 kilometers at high speed? The pack weighs about 150 grams, which is only 50-70 grams heavier than a standard battery.

 

[Mr Man]

An 18650??? Or do you mean an 1800?? An 18650 would be like the size of a brick

 

[Foamforce]

An 18650??? Or do you mean an 1800?? An 18650 would be like the size of a brick

That’s a common lithium ion cell. Long range flyers like to use them. They have lower discharge rates, so you can’t fly them as hard, but they have better capacity for range.

Andrej, the battery compartment is pretty small. I’m not sure you could fit three of them in there, particularly while achieving balance. However, you could slightly modify the plans to make the fuselage wider and put them in side by side. The arrow is usually a little tail heavy, so the extra weight of 3x 18650 in the nose would probably help it balance easily without having to cram then all the way to the front.

Have you looked at the spear? You could probably pack at least a 3s2p in there, if not 3s3p (with creative pack configuration).

 

[Tree Feeder]

Put them in the leading edge of the wing.

 

[LitterBug]

21700s aren't much bigger than 18650s but have much higher capacity and current ratings.

 

[Mr Man]

That’s a common lithium ion cell. Long range flyers like to use them. They have lower discharge rates, so you can’t fly them as hard, but they have better capacity for range.

Andrej, the battery compartment is pretty small. I’m not sure you could fit three of them in there, particularly while achieving balance. However, you could slightly modify the plans to make the fuselage wider and put them in side by side. The arrow is usually a little tail heavy, so the extra weight of 3x 18650 in the nose would probably help it balance easily without having to cram then all the way to the front.

Have you looked at the spear? You could probably pack at least a 3s2p in there, if not 3s3p (with creative pack configuration).

ah, ok

 

[andrej]

An 18650??? Or do you mean an 1800?? An 18650 would be like the size of a brick

The 3S pack weighs about 150 grams. Probably comparable to a 1300-1500mAh lipo. The problem here is more likely to require modification of the fuselage.

 

[andrej]

21700s aren't much bigger than 18650s but have much higher capacity and current ratings.

I have a 21700, and the 3s weighs 225 grams compared to the 18650's 150 grams. So, I'd need a little more
wingspan, at least about a meter. I'd like something more compact, and the Arrow seems like it would be compact enough for my needs.

 

[Houndpup Rc]

ah, ok

These batteries: (They are in rechargeable head lamps a lot are are basically bigger and lighter for the size than AA's)

 

[Houndpup Rc]

An 18650??? Or do you mean an 1800?? An 18650 would be like the size of a brick

That would be a touch big!🤣

 

[Mr Man]

That would be a touch big!🤣

yup 🤣

 

[LitterBug]

These batteries: (They are in rechargeable head lamps a lot are are basically bigger and lighter for the size than AA's)

Those are NOT legitamate 18650 cells. You can NOT get 9900 mah into an 18650 case. Even if you could you would have a discharge rate of.0001 amp.

Your biggest capacity 18650s are in the 3500mah range. the Higher the discharge rate, the lower the total capacity is. There are trade offs between capacity and current draw.

 

[LitterBug]

I have a 21700, and the 3s weighs 225 grams compared to the 18650's 150 grams. So, I'd need a little more
wingspan, at least about a meter. I'd like something more compact, and the Arrow seems like it would be compact enough for my needs.

OK. I was basing it on size not weight. I will compare a few of my cells.

2x18650 96g
2x21700 137g
these weights are for the raw cells, not built packs

 

[Houndpup Rc]

Those are NOT legitamate 18650 cells. You can NOT get 9900 mah into an 18650 case. Even if you could you would have a discharge rate of.0001 amp.

Your biggest capacity 18650s are in the 3500mah range. the Higher the discharge rate, the lower the total capacity is. There are trade offs between capacity and current draw.

Ahhhh okay👍

 

[Houndpup Rc]

Ahhhh okay👍

*I couldn't find any pics of the cells I was thinking off...All I could see was the "performance" packs and I didn't know there was a difference is size ect😂👍

 

[andrej]

If I have 3mm and 6mm Depron, which do you think is better? If I plan to fly between bushes, I'm leaning more toward 6mm.
Since the original foam is 5mm thick, should I make any modifications to the plans?
Should the spar height be reduced by two millimeters? Otherwise, the wing will be a couple of millimeters thicker.

 

[Jo's squadron]

If I have 3mm and 6mm Depron, which do you think is better? If I plan to fly between bushes, I'm leaning more toward 6mm.
Since the original foam is 5mm thick, should I make any modifications to the plans?
Should the spar height be reduced by two millimeters? Otherwise, the wing will be a couple of millimeters thicker.

I’ve built some 80% FT planes without much modifications and it still worked great. So I think it should be fine with 6mm👍

 

[andrej]

I built it out of 6mm Depron. It's empty so far. It weighs 99 grams. I estimate that with an 1806 motor and 3S 850mAh, it would weigh around 250 grams. If I didn't use hot glue, but a decent one like cyanoacrylate or Uhu-por, and made it out of 3mm foam, I think I could shave off another 50 grams. But that wasn't my goal.

 

[andrej]

Today was the maiden flight of the Arrow. The elevon reflex was set according to the template, but it was necessary to trim the elevons up a couple more degrees for level flught. There was a slight wind, and the wing is very sensitive to it, flapping around a lot. The entire plane weighs about 260 grams. The motor is an 1806, so it seems a more powerful motor would be helpful.

On the plus side, it's very maneuverable and responsive. The rates need to be cut.
Overall, I think it'll be fun to fly in calm weather, but I expected it to be more stable in windy conditions.