How close is too close in terms of placing the battery near the engine? What sort of protection is needed?

Hi Abufletcher,

There is no such thing as 'too close' as long as the battery is isolated from vibration. You might not want to keep it totally up front, to prevent more severe crash damage, or at least put a bit of styrofoam around it to absorb impact. That would be in addition to regular sponge rubber foam for vibration protection.

I would also make sure that it's isolated from the firewall as well as the engine, but secured in well enough that it doesn't float around in flight, which would change your CG. And make sure that the intake isn't blocked.

Just my $.02

... and enclose it in something fuel proof. As close as it is to the carb, it will get fuel wet routinely. Check it and clean it occasionally.

Attach another picture of the aircraft. Looks very interesting.

Bedford

Wot they said...it will end up as far from the balance as needs to put the balance in the right place. Often they end up under the tank, sometimes behind the wing, I've even had them beside the engine under the cowl. Consider it ballast, just keep it vibration isolated and fuel proof.
Evan, WB #12.

From looking at your pic, you will need to protect the battery from the screws coming through the motor mount. It is okay to put it up against the firewall if you need to, but as mentioned, you need to protect it from fuel and vibration. s I said you will need to make sure tht your screws do not come in contact with the battery. Good Luck, Dave

You also can't block the carb intake.

Looks like I may have to accept that I can't fit the battery (or at least the battery I currently have available) in the forward part of the engine compartment. There's just no room for it once it's suitable wrapped in foam. I may have to put it back with the received and then add some lead in the front area.

I have extended the engine box on models out under the engine to mount batteries as far forward as possible for balance reasons but I've done that at the design stage.

Probably too late for you now. - John.

You're trying to fit a flat pack in there. Would a square pack work? i.e., a 2x2 pack?

Just a thought,

Bob

Thanks for all the good advice. In the end, I just chose a "get-er done" solution and velcro'ed the battery to the hatch and then velcro'ed a piece of foam on the other side of the battery to provide some minimal protection from fuel.

Nice lookin SE5 Abu.

ZZ.

If the (currently rainy) weather allows, I'll do the maiden flight this coming Sunday.

This may be overly cautious, but you may want to wrap a plastic baggy around your receiver. Even though you've deflected the exhaust nicely out the bottom, you may still get a little gunk sucked back up through the aft vents of the removable bottom panel. It would only be a little bit at a time, but after 50 flights, your electronics may be an oily mess.

I agree. I really prefer to have the RX (and the battery) completely isolated from the engine compartment.

Definatley rap the electrics in some plastic.
You're using a  stroke, inverted carb.
It'll be spitting fuel... nothing you can do about it.

VERY nice job BTW!

Nice work Don.

Balloons work well for protecting the electronics from fuel etc.