Returning after decades so not total Newbie!

[Chris King 3]

The Spec for my ESC says it cuts off power at 5V - would that be OK for a LiPo?

[Steve Hargreaves - Moderator]

Sounds too low to me Chris.....LiPos don't like being run down to much below 3V per cell.

ESCs are so cheap these days surely best to just buy a new one?

[Chris King 3]

Youre probably right but thats two ESCs as I want to fly two models.

All the component parts are much cheaper now. Its funny looking at the prices on the boxes for stuff I bought before I stuck it all up in the loft!

Original plan was fly one finished park flyer and finish my foamie spitfire with the minimum of hassle/cost. Doesn't look like its as simple as buying a couple of new batteries!

[Chris King 3]

Just in case someone else finds this post with a similar dilema - this is what I did in the end.

I bought some 9.6v 1600mAh NiMh 2/3AA cells. The originals were 1000mAh and 4/5AA so theres a small weight saving.

To test them I ran at full throttle for 5 secs and then about 3/4 throttle until the ESC cut. It seems to produce the same power as the NiCads but will run for over 25 mins which Im sure is a lot longer than the old NiCads used to go for!

Many thanks for all the suggestions and the heads up on the new technology. I have a couple of other planes that need motors so the info will come in handy with getting those flying again. Im hoping brushless outrunner motors will allow me to do away with the gearboxes they both used.

[Chris King 3]

...and to complete the story I finally got around to flying the model last weekend and as some had predicted the performance was somewhat lacking so I think internal resistance with the NiMH is an issue!

It basically runs on full throttle and struggles into the sky! I'm sure the performance was far better when I used to fly it even though it's stretching the memory somewhat as it was 20 yrs ago!

I'm in the process of finishing an old Astra Spitfire model (link here: Link ) and have upgraded to Brushless and Lipo for that. I think this old plane deserves a fair chance to fly again properly so I think I'll upgrade battery, Esc and brushless motor on this one.

There were some very helpful suggestions on setup for my other model. Any suggestions for a starting point for this one please?

It's a Scorpio Miss Moravia low wing (with dihedral) slow flyer. Original Spec is 147cm span, (original) weight 850g Speed 400 motor direct driving 8-4" prop.

[Simon Chaddock]

If it looks anything like this

The issue is just how much lighter do you want it to be!

For the same power brusshless is half the weight and are more efficient. LiPo have roughly twice the capacity for the same weight.

My suggestion would be to keep more or less the same power 160W 1500kV brushless and a 1500 mAh 3s LiPo driving a 7x6 e prop.

It will still be significantly lighter so even with the same sort of electrical input power it will have a noticeably better performance and with twice? the battery capacity and improved motor efficiency it will have a considerably longer duration, maybe as much as 3 times!..

[Chris King 3]

It is that model but mine doesnt have ailerons and certainly doesnt take off like that one!

I'm not looking for more lightness as such, just better performance.

Thanks for the suggestions, I already have a couple of 1500 mAh 3s LiPos which I bought for my other model Im converting so I can try these so just need the motor and Esc.