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12V versus 24V

cable size/weight

Only the one wire going to the starter motor (the return is mostly via the airframe).

48V aircraft batteries will be very lightweight

How?

40 minutes of endurance gone.

The IAS barely varies with weight, at GA cruise speeds. In terms of extra fuel which could be carried, that may be the case.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

Only the one wire going to the starter motor (the return is mostly via the airframe).

With plastic Cirrus being the #1 selling brand, I think the adverb “mostly” is misplaced here

How?

48V aircraft/car batteries also include the step from lead acid to lithium chemistry.

The IAS barely varies with weight, at GA cruise speeds.

Yes but 15kg less battery means 15kg more luggage/belly with the same structure, doesn’t it?

With plastic Cirrus being the #1 selling brand, I think the adverb “mostly” is misplaced here

OK, two wires then. A few kg at most, and you create a huge pile of issues. Now you need 48V lamps everywhere… and that is just 1% of your problems.

48V aircraft/car batteries also include the step from lead acid to lithium chemistry.

I doubt it when you look at the pricing of e.g. the stuff here – €7k

Yes but 15kg less battery means 15kg more luggage/belly with the same structure, doesn’t it?

Yes but I doubt there is a plane flying whose W&B schedule is within 15kg of the real one

Administrator
Shoreham EGKA, United Kingdom

7k€ two years ago… 4.4k€ now. Another one / two years they might even be affordable (in aviation terms). And that is without accounting for USD appreciation over the time period.

Last Edited by Shorrick_Mk2 at 26 Nov 17:24

Peter wrote:

I doubt it when you look at the pricing of e.g. the stuff here – €7k

Prices will go down. Cars are making the step now, aircraft will make it in due course.

Yes but I doubt there is a plane flying whose W&B schedule is within 15kg of the real one

OK, so 15kg don’t matter. Then another 15kg don’t matter either and another, etc. That argument doesn’t hold up. 15kg is a lot in a 4 seater. Not many other straightforward ways to shave off 15kg.

How much would you spend to save the weight delta between the two batteries?

IMHO this is a very long way from being a fish worth frying for piston GA.

OTOH I know someone who spent something like 10k certifying a kevlar oxygen cylinder for a TB21.

Administrator
Shoreham EGKA, United Kingdom

Asking the “how much” question when spending 50k on a FIKI kit for a 180k airframe instead of flying commercial business class in any weather….

For the rest there is MasterCard.

Do you fly a plane these days, Shorrick? You did fly a Mooney at one point… It will do you a lot of good to get back into GA. Then you could make one of our fly-ins, instead of posting loads of silly comments like this.

Administrator
Shoreham EGKA, United Kingdom

Well I think the comment has some merit because 50k for TKS on a TB20 and 10k for an oxygen bottle on a TB21 are two examples of the same thing…

I can confirm that Shorrick flies aircraft. I can also confirm that Shorrick eats pizza calzone.

To get back on topic — I believe there is a significant benefit going 48V lithium in aircraft. Cessna and others did the 24V jump around 1978 and it required a lot more components to change because it was all discrete light bulbs and avionics. A 2017 GA aircraft is G1000 and LEDs both of which can easily work with a very wide voltage range. Each production year of the Cirrus et al needs to some some small goodies and 15kg extra loading, a better COG, a faster turning and stronger starter, the modern sound of 48V/lithium etc. are things worth printing on the brochure to justify the yearly 2% price increase.

You are comparing (a) a TKS ice protection install with (b) replacing a steel bottle with a kevlar one???? Everybody knows you love doing windups achim but this is just a waste of bandwidth.

Administrator
Shoreham EGKA, United Kingdom
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