• Welcome aboard HomebuiltAirplanes.com, your destination for connecting with a thriving community of more than 10,000 active members, all passionate about home-built aviation. Dive into our comprehensive repository of knowledge, exchange technical insights, arrange get-togethers, and trade aircrafts/parts with like-minded enthusiasts. Unearth a wide-ranging collection of general and kit plane aviation subjects, enriched with engaging imagery, in-depth technical manuals, and rare archives.

    For a nominal fee of $99.99/year or $12.99/month, you can immerse yourself in this dynamic community and unparalleled treasure-trove of aviation knowledge.

    Embark on your journey now!

    Click Here to Become a Premium Member and Experience Homebuilt Airplanes to the Fullest!

Parallel hyrbid V-twin (or 1/2 VW) belt PSRU idea

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

markaeric

Well-Known Member
Joined
Jul 31, 2015
Messages
346
Location
Wichita
Hello all! It's been a while since I've been around as life tends to do what it often does and gets in the way of having fun. But despite that, it didn't entirely stop me from thinking about airplane-y things.

Couple months back I was thinking about how a ~40HP Briggs V-twin could be boosted to around 60HP without having to do significant internal modifications (and then try to ensure that the block could take it). I was interested in this power level because the Merlin PSA appears to have great takeoff performance when it uses an engine with that kind of power. One thought led to another and another and another until I thought about the following:

Incorporate an outrunner-type electric motor into a belt PSRU by doubling as the large pulley. For example, look at the image below

rex_30_06.jpg


For those that don't know, on an outrunner style electric motor, the outside housing is the rotor, which is the opposite of the more common inrunners that everyone is familiar with, hence the name. In the image above, it almost looks as if the outside is grooved for a multi-groove belt, which should help give you an idea of what I'm talking about.

So while replacing the typical big pulley in a PSRU with an electric motor/pulley combo would add some weight, it'll be possible to at least partially offset it by getting rid of the engine starter and alternator stator, since the motor on the PSRU can serve that functionality instead.

Of course, an electric motor is useless without a power source, and I think that's where most of the trade-offs have to be made. I calculated 17lbs worth of cells alone (not including a pack housing) for ~3 minutes worth @ 15kW (not accounting for motor and ESC losses), using the relatively heavy but safe LiFePO4 chemistry. On the upside, the battery pack doesn't have to be in front of the firewall.

Given the fairly low power density of batteries, the main intent of this setup is to boost the output of the powerplant primarily during take-off and initial climb. If you're "lucky" and needed a ballast anyway, then batteries would be a doubly useful solution. Powerplant weight wouldn't be increased significantly (if at all) over an engine with a starter and alternator using a standard PSRU.

Any thoughts?
 
Back
Top