Search found 280 matches

by Bumpkin
Sat Mar 23, 2024 12:18 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: These things really are toys...
Replies: 26
Views: 349

Re: These things really are toys...

Vincent, as to the drop from expected 7psi to measured 4psi in your opening post, did you add around the displacer to dead-space? I'm sure it doesn't bottom or top out, and it's probably an annular gap type regenerator? As to that, without a proper regenerator, much more of the working gas temperatu...
by Bumpkin
Sat Mar 16, 2024 11:30 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Alpha stirling engine working principle
Replies: 8
Views: 156

Re: Alpha stirling engine working principle

I've never seen it explained well, and this probably won't help; but I'll take a stab at it: Visualize a single-crank-pin 90 degree V twin Alpha. Minimum volume is the crank centered at 45 degrees between the cylinders and maximum is 180 degrees further along, similar to tdc to bdc of a Gamma power ...
by Bumpkin
Thu Mar 14, 2024 6:39 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Model LTD max power effort
Replies: 106
Views: 36955

Re: Model LTD max power effort

To be clear, I've never proposed that radiant transfer has any effect on clear air; in. fact the opposite. I've only said that I think radiant heating of a heater, and radiant cooling of a cooler, that would then conduct heat to/from the working fluid, could be very significant. Apologies for any mi...
by Bumpkin
Thu Feb 22, 2024 10:30 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: BETA Timing/First post
Replies: 3
Views: 221

Re: BETA Timing/First post

A problem with the Beta is that changing timing changes the clearance between piston and displacer, so you'll need to allow for that in the different experiments.

Bumpkin
by Bumpkin
Wed Feb 14, 2024 10:50 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: First stirling engine - can't get running
Replies: 15
Views: 888

Re: First stirling engine - can't get running

I googled that plan and it showed a smaller version with a 15 mm displacer and a 13 mm power piston. With the single crank throw and rocking beam design it looks like the stroke is the same for both. If your bigger version has a similar displacement ratio it would take a very high temperature ratio ...
by Bumpkin
Sat Jan 27, 2024 11:36 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Stirling engine fan for top of woodstove
Replies: 18
Views: 1711

Re: Stirling engine fan for top of woodstove

I was gifted one of those peltier fans - "I Know you live off-grid and you'll just love this." It worked silently and reliably and pretty much uselessly. I either threw it away or it's stored away somewhere, I dunno. Not that they couldn't serve a purpose, but the best way to spread the he...
by Bumpkin
Mon Jan 15, 2024 10:11 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: New me at the forum
Replies: 2
Views: 891

Re: New me at the forum

Welcome to the forum. Sorry to miss and not greet your introduction. Sometimes I'm here regular and sometimes not so much. Sounds like we have a lot in common as far as appropriate-tech independence, along with dreams of fostering community. I have genuine respect for true black-smithing. I tend to ...
by Bumpkin
Sat Jan 06, 2024 10:21 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Presentacion
Replies: 1
Views: 789

Re: Presentacion

Welcome Fusval. I've taken the liberty to share an english translation I found: I am determined to come forward and take an active role in this forum. I'm one of many people who are passionate about mechanics and lately I've been interested in these engines and all the engineering challenges they br...
by Bumpkin
Wed Jan 03, 2024 11:30 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: 55-gallon barrel Stirling
Replies: 22
Views: 19871

Re: 55-gallon barrel Stirling

I finally got back to this a bit. I got the fire-box door done. I think I’ll pick up a few extra lengths of stove-pipe next time I get to town so I can take it outside and burn off all the old paint and see how it draws. I’ve made a few wood-stoves and they’ve all drawn ok, but this one was made wit...
by Bumpkin
Wed Jan 03, 2024 10:36 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
Replies: 132
Views: 8711

Re: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)

When I saw the above question, “How do you define heat?” I knew it wasn’t asked of me, but I thought: (As a noun,) Molecular motion duh. That “official” Britannica definition is too clever by half. If instead of “energy that is transferred,” they were to say “energy that has the potential to be tran...
by Bumpkin
Tue Jan 02, 2024 10:05 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Modified "Hot" Beta engine
Replies: 146
Views: 25546

Re: Modified "Hot" Beta engine

I could diagram a 10/1 or maybe even a 100/1 compression Beta, but it couldn’t run without a 20/1 or 200/1 temperature difference. So there’s really not much point. It seems idiots are idiots — higher indoctrination just reinforces the bastion.

Bumpkin
by Bumpkin
Sat Dec 16, 2023 6:23 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Perpetual Ideas
Replies: 78
Views: 74991

Re: Perpetual Ideas

Dunno if it relates and I can’t remember if it was this forum or somewhere else, but there was a conversation sometime back about how the roughness of shark-skin actually made it slicker. Yeah I know, hydrodynamics vs aerodynamics, but it might be relevant.

Bumpkin
by Bumpkin
Thu Dec 07, 2023 7:27 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: "Thermoacoustic" Stirling - theory of operation
Replies: 129
Views: 162127

Re: "Thermoacoustic" Stirling - theory of operation

Tom, thanks for catching my spelling error and correcting it; principal — principle, perhaps without even noticing. Maybe the principle was more important. Like you said, (paraphrased,) it’s probably not the sound of the hammer-strike that’s driving the nail. As in; if you really want to advance sci...
by Bumpkin
Wed Dec 06, 2023 4:38 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: "Thermoacoustic" Stirling - theory of operation
Replies: 129
Views: 162127

Re: "Thermoacoustic" Stirling - theory of operation

Yeah, that’s the patent drawing, but as with Stirlings, the principal is more important than the machine, which could of course take many forms. Tailer’s premise was that the natural lag in heating/cooling would cause higher average pressure on the power stroke than the compression stroke, and he ev...
by Bumpkin
Tue Dec 05, 2023 9:24 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: "Thermoacoustic" Stirling - theory of operation
Replies: 129
Views: 162127

Re: "Thermoacoustic" Stirling - theory of operation

I think these engines have a lot of potential, but it irritates the heck out of me when folks call the mesh heat exchanger in a thermal lag engine a regenerator. If I’m wrong in not seeing how that’s possible, I wish somebody smarter would come along and enlighten me. I’d seriously welcome what coul...