VW Heads Designed for Aircraft- Poll

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Value of purpose built VW aircraft heads

  • Why bother. Who would try to use '30's auto technology to fly.

    Votes: 1 4.2%
  • It's an interesting idea but what we have now is good enough.

    Votes: 2 8.3%
  • If they were close in cost AND better I'd probably use them

    Votes: 11 45.8%
  • It's been needed for a long time. They will make the VW a far better option.

    Votes: 10 41.7%
  • It would be the best thing to happen to EABs in the last 2 decades

    Votes: 0 0.0%
  • Why bother. Who would try to use '30's auto technology to fly.

    Votes: 1 4.2%
  • It's an interesting idea but what we have now is good enough.

    Votes: 2 8.3%
  • If they were close in cost AND better I'd probably use them

    Votes: 11 45.8%
  • It's been needed for a long time. They will make the VW a far better option.

    Votes: 10 41.7%
  • It would be the best thing to happen to EABs in the last 2 decades

    Votes: 0 0.0%

  • Total voters
    24
  • Poll closed .

Aviacs

Well-Known Member
Joined
Oct 21, 2019
Messages
311
for whatever reason, the "fineness" of the fins on these cast heads appears to be limited (e.g instead of 8 fins, could they cast 10 fins in the same distance?). Now, they need to be thick enough to survive and to carry heat their full length, and sufficient air must move through the slot between them. But, given that, more fins per inch = more surface area for heat exchange = cooler heads. Can we get better fins if we extrude or cut them? Cost?
Re: finning, the common aero comparison is between traditional Lycoming cylinders (larger, fewer fins ) being designed to "withstand" heat, vs Continental being designed to "shed" heat. Also, based on fin theory, there are a range of options and a specific cross section. "more/thinner" is not necessarily better, at some point.

The Porshe heads machined from solid aluminum block ("Billet" is a sales word that annoys most machinists - a billet is the rolled blank you sometimes see on a flat bed, headed somewhere to be divided down and rolled or cut to small blanks) seem to work? So one avenue for design exploration. Nonetheless, casting is more likely to approach optimum fin shape (cross section).

I'm going to beat on is some more:
Casting, per se, is not the inhibiting cost factor in most cases. If it is, with complete designs and a stated volume (# of parts), it is easy to compare with a "cnc"'d analogue. A foundry will quote per part, based on volume, that appoaches the retail raw metal cost. They of course have to remove the mould & cores from the casting, cut off the sprues and risers, and lightly de-flash/deburr. ("snag" the castings). For a complex item, about 1/2 the metal poured becomes your casting, the rest (risers, pouring basins, sprues, runners) goes back in the pot. A foundry does need enough volume to amortize the rigging they design, develop, and apply to your pattern to make it pourable; + perhaps a few test pours to prove it. This is what makes only one, or only a"few" castings so expensive.

The real, big, costs of getting a part out of the wishing stage is 1.) thorough design and engineering. 2. tooling.

smt
 
Last edited:

sotaro

Well-Known Member
Joined
Feb 26, 2011
Messages
212
Location
San Francisco
Re: finning, the common aero comparison is between traditional Lycoming cylinders (larger, fewer fins ) being designed to "withstand" heat, vs Continental being designed to "shed" heat. Also, based on fin theory, there are a range of options and a specific cross section. "more/thinner" is not necessarily better, at some point.

The Porshe heads machined from solid aluminum block ("Billet" is a sales word that annoys most machinists - a billet is the rolled blank you sometimes see on a flat bed, headed somewhere to be divided down and rolled or cut to small blanks) seem to work? So one avenue for design exploration. Nonetheless, casting is more likely to approach optimum fin shape (cross section).

I'm going to beat on is some more:
Casting, per se, is not the inhibiting cost factor in most cases. If it is, with complete designs and a stated volume (# of parts), it is easy to compare with a "cnc"'d analogue. A foundry will quote per part, based on volume, that appoaches the retail raw metal cost. They of course have to remove the mould & cores from the casting, cut off the sprues and risers, and lightly de-flash/deburr. ("snag" the castings). For a complex item, about 1/2 the metal poured becomes your casting, the rest (risers, pouring basins, sprues, runners) goes back in the pot. A foundry does need enough volume to amortize the rigging they design, develop, and apply to your pattern to make it pourable; + perhaps a few test pours to prove it. This is what makes only one, or only a"few" castings so expensive.

The real, big, costs of getting a part out of the wishing stage is 1.) thorough design and engineering. 2. tooling.

smt
Got me! I had looked at that motorcycle design in the last 6 months. Moto Morini... It is true that I don't think of Heron heads as being high performance, and the Morini was thought of as being so... Memories, so fleeting.
 

sotaro

Well-Known Member
Joined
Feb 26, 2011
Messages
212
Location
San Francisco
What about additive printing longer fins, or extra fins on production heads, or on a new head that would be too expensive for the low volume, to make as good at heat rejection as we need?
 

sotaro

Well-Known Member
Joined
Feb 26, 2011
Messages
212
Location
San Francisco
View attachment 120437View attachment 120441
Seems about the same, heart chamber piston looks sleeker.
WaterBoxers were also Heron Heads. No to air cooled pairs.
You got me! I looked at the Moto Morini in the past 6 months. It is a conundrum that the Heron head is not considered high performance, and yet in it's day the Morini was high performance. Cost control was central to Morini's success, and the Heron head was part of that.
 
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