Airspeed Record.

[john stones 1 - Moderator]

https://www.bbc.co.uk/news/business-57747128

[J D 8]

Nice sleek looking model that would make. Like the detail of having tailwheel in the rudder, no extra steering gear needed. 

Their batt's look somewhat behind the times net to what modelers use today but cooling does become a major issue with larger units.

[Simon Chaddock]

Condensing all the batteries into a lump and than having to liquid cool it does seem a very conventional approach.

Unlike a car a plane has to have quite a bit of surface area with high speed air passing over it. Why not seek to make use of it with a 'distributed' battery?

[Peter Jenkins]

12 hours ago, Simon Chaddock said:

Condensing all the batteries into a lump and than having to liquid cool it does seem a very conventional approach.

Unlike a car a plane has to have quite a bit of surface area with high speed air passing over it. Why not seek to make use of it with a 'distributed' battery?

You mean like this?

[Simon Chaddock]

9 hours ago, Peter Jenkins said:

You mean like this?

Peter

Not quite. The Zephyr goes for extreme duration by sacrificing speed and discharging its batteries over a period of many hours (a rate of just a fraction of a C) so the rate of heat discharge is very low.

My idea for a high discharge type flight would be to distribute the batteries over the surface of the plane so every individual cell would be adjacent to the airspeed airflow. 

[Peter Jenkins]

Simon

Just to understand from where you are coming.  Are you "in the business" or would just like to see someone produce a solution with distributed batteries out of interest?

[Martin_K]

On 23/07/2021 at 11:09, Simon Chaddock said:

.... Why not seek to make use of it with a 'distributed' battery?

Possibly because high current requires beefy inter battery connections. Too much metal work to fan out across the airframe?

[Simon Chaddock]

 

41 minutes ago, Martin_K said:

Possibly because high current requires beefy inter battery connections. Too much metal work to fan out across the airframe?

As far as I am aware these batteries use hundreds(s) of individual cells and alarmingly high total voltages which means there must be quite some number of cells in series. There is no real penalty in arranging each line of series cells in an 'out and back' arrangement with no particular connection weight penalty.

Obviously packing the cells close together makes the connections for cell monitoring & balance charging simpler (important in a car) but for a speed record I am not sure this would be an obstacle.

Just thinking outside the box.

 

[Don Fry]

I think the liquid cooling system is as it is to provide even cooling of each of the thousands of cells. I would guess the aircraft skins are used as the face of the cooling radiators, avoiding the need of draggy in airflow radiators. 
There was an (unsuccessful) Russian fighter in WW2, used this type of cooling. It needed to take off before it boiled over, and could not hang about on the ground.

[Martin_K]

Simon, I just read up on the project. (Article 1 year old). Apologies if you know the following already.

 

From the report, there are 3 AC motors driving a common prop shaft. 3 battery packs, one per motor, supply power. Inverters convert battery output to AC. Cooling is required for the batteries, inverters, and motors. This is not done via separate pipe work. In the case of the motors, at least, coolant fluid flows directly through the motors. The speculation is that technology is borrowed from car racing.

 

This does not answer your question in general but points to us needing to think about the whole system as used in this aircraft.

[Peter Jenkins]

The speed record was finally approved by the FAI on 20th Jan '22.  See link.

 

On November, 16th, the aircraft reached a top speed of 555.9 km/h (345.4 mph) over 3 km, beating the previous record by 213.04 km/h (132 mph). It also reached 532.1km/h (330 mph) over 15 km, which is a figure 292.8km/h (182 mph) quicker than the previous record holder.