Veco 19s can haul. They were for years the preferred power for many in Clown Racing at Brodak. Acquitting themselves well against more race dedicated engines. There was a Nats winning stunt flier from the East Coast who flew a Humbug, I believe, with a Veco 19. He didn't win with this particular combo, but placed high enough to raise controversy. Since this comparatively small power plant hung on a flapless long winged plane was defiantly unlike the orthodox. Looking at Eric Rule's cite, I see the Humbug spanned 58" and weighed in at 44 ounces. I have seen many speed limited combat planes ripping fast with LA 25s up front. These planes are not small. Pull out the venturi, stick on a bladder, needle until the LA 25 hits a teeth drilling screech. We've tacked these engines at 20 thousand and above. Since they pull these foamies with biggish wings near eighty miles an hour, I have to agree, yes, there's plenty of power to do a Twister through the pattern. How different in approach tho to the sweet flying, docile, ARF Flite Streak I saw last weekend, using the self same LA 25 to power a fairly light shorter winged stunt/trainer at speeds (and with a level of responsiveness) friendly to pilots new to stunt.
This evening I was talking with a friend who builds race cars, hot rods and the like. A man having built countless fast and REAL FAST engines by this time. My newest Twister sized profile on the dining room table (a flapped Magician powered by a Tower 40 with.... head gaskets... and...). Contrasting this plane with the inverted mounted engines on a few full bodied planes nearby, he thinking that the inverted engine would feed better and so forth. Then I said, well no, not necessarily since the engines are subject to so many different and constantly changing forces. Then I started to explain a usuable/ideal stunt run. How these SIMPLISTIC engines can be tuned to increase power in this part of the maneuver, reduce power in that part of the maneuver, switching off and on in modes, how altering the compression, fuel, venturi size, prop, tank type, tank height,(and... and.. and...) how these tuning methods can be after much guesstimation recipeed (sp) to work on a given field at given temperatures... to deliver a near optimum stunt run...
It's 4:30 am on the right coast time for delusions and insights. Here's my thinking at the moment. Our 2 stroke power plants are comparatively simple in design. We are attempting to make these simple engines do very complex things. Up power, lower power in micro seconds, responding in specific ways to big differences in loads, a wide variety of loads, ridiculous challenge. Impossible. Certainly in the abstract. What would the vector analysis look like if we tried to make an accurate diagram of all forces that actually act on an engine/fuel delivery system in, let's say, a loop. Arrows, every which way. Then add the indeterminacy of a given days barometric pressure, relationship to sea level, temperature, humidity, fuel mix. On and on.
So. What's up. What do we do. How do we handle the near impossible complexity of simple, pragmatic technologies. Like throwing rocks. Or boomerangs. Or designing dug out canoes. Or designing sailing ships to go up the Nile. Or. Seems to me we do what we've always done. Trial and error, educated guessing, in other words experience as teacher. Which means, some of us will turn out to have a better feel, a better intuition, a better way to balance out this complexity, so that a workable, doable, effective solution is derived. An effective solution is not the same, in fact it often is contrary to, a philosophical debate of abstractions.
My conclusion. Find a mentor who makes the sh-t work. This is different from taking advice from someone who SOUNDS convincing. Often the folks who make SH-T work may or may not be able to explain why the SH-T works. In fact they may be dead wrong in their explanations... But they have a feel, an intuition, an internal math(?) physics(?) brilliance(?). Listen to them. Try their approach. Then try their approach again.
My thought for the person who started the thread. Sounds like you've got some mentors around who know their SH-T...
Topic: LA 25 in a Fancherized Twister? (Read 11654 times)