nlappos

Laying in a 220V outlet in the garage is pretty easy, here are some videos: 

https://www.youtube.com/watch?v=X9ro7Tc2nFI

https://www.youtube.com/watch?v=u296hiXRzlE

Turbo,

It is great to have your aerodynamic expertise on this site - drop back from time to time and share, OK?

Rotax Rick is pretty reasonable, and his quality is great. He charges $1850 to $2200 for an overhaul of a 582

Jim Chuck has a good memory, this was posted by one of the yamaha guys.

Allen, don't worry too much about CHT, the EGT will cook your engine in seconds. Basically, when trimmed at high speed cruise at high EGT (for gas efficiency) do not dive the airplane, this will make the rpm rise and the EGT will go very high very fast. In 10 seconds you can lunch your engine. To descend from high speed cruise, slow down first, then pull back the throttle.

Avidventurous,

If you want a bit more power than the 582, talk to Rotax Rick about swapping your 582 core for a 670. I did and it is great! The install is a pure drop in for the 582, as well.

I removed my Maule and put on the Matco single arm wheel, it is lighter and less expensive, and I am not sure the dual arm has any great advantage.

The pneumatic wheel is terrific, and is also so much quieter! It took a bit to get it to not shimmy, just follow the directions.

109jb

I am putting a bunch of Tesla batteries in my new off grid house and have learned a bunch about them. For our purposes, while the weight savings is fantastic, the down side isn't

Freezing weather is one, they really misbehave if you charge or discharge them below freezing. Also, the battery monitor has to be unique to the type of Lithium battery, in terms of the allowed max voltage, charge rate and such. 

I wanted to go the route you thought about, then went to Walmart and bought another lawn tractor battery!

My header is not vented, the wing fuel flows into it, and it has lots of headspace to collect air, which I expel prior to every flight. I open the valve on the top and drain the fuel onto the ground, thus assuring that the air is let out first.

Fantastic work! please keep us informed.

Simply said, you said that Drag is not proportional to Vsquared, and implied that it is not that big. It is, in fact it is bigger than Vsquared. Can you at least admit that?

109jb,

Your discussion is helpful, your math, not so much.

Total drag = Parasite + Induced drag. That means the Vsquared Parasite drag is ADDED to the Incuded drag to make total drag, so Total drag goes up by MORE that Vsquared. Somehow you think Induced drag is subtracted from parasite drag in the process, where this came from, I don't know. The fact that Total Drag line on the plots you provide is ABOVE Parasite drag is lost you you, but it shows that total drag is more than parasite, so it goes up to a higher value than parasite drag. Total drag rises faster than Vsquared, my friend.

Here is nice discussion:

http://www.pilotfriend.com/training/flight_training/aero/drag.htm

Oh for Pete's sake, save us the internet version of anti-vaccination, ok, 109jb. Or else write NASA and tell them your crackpot theory. Until then, drag goes up by V squared, and in fact power required goes up by V cubed. 

https://www.grc.nasa.gov/WWW/K-12/airplane/drageq.html

I am really skeptical about putting a few fairings on an Avid and getting 10 or 15 mph more cruise out of it. Physics argues otherwise.

Drag goes up by the square of speed, so if you want the same power to get you from 90 mph to 100 mph (let alone the 120 mph someone posted here!), you have to cut the drag by 20%. How many gas caps does it take to equal the drag of that big wing? Or the fuselage cross section? Or those long double struts?

To get to 120 mph, you have to drop the drag by almost 80%. 

Yes, I installed it about 2 years ago. It has dual ignition, and Rick did a quality job on it. Runs like a top. I really need it, I am at 6000 feet here, and have 11,000 feet DA in the summer.

I posted a bunch about it on a thread, will post the link.

Here is the link to the factory pull sheets for the Mk IV kit:

http://www.avidfoxflyers.com/index.php?/topic/308-factory-pull-sheets-for-mk-iv-taildragger/

Here is the long thread about the 670 install and flight test:

http://www.avidfoxflyers.com/index.php?/topic/5734-new-rotax-670-install/

One idea on that engine, (assuming it is a dual ignition one, which is most likely) swap it for a 670, which has 91 horsepower. Rotax Rick did mine, and it was about 3550 plus the 582 for a perfect 670.

Regarding the kit, a big question is how complete the kit is. Instruments and hardware can really mount up in cost. There is a MK IV parts inventory on this site, might want to work with the seller to check it out.

Ernest  K. Gann:

• Island in the Sky. New York: Viking, 1944
• The High and the Mighty. Cornwall-on-Hudson, New York: Sloane, 1953
• Fate Is the Hunter (memoir). New York: Simon & Schuster, 1961

Pascal,

When I installed my Highwing gear, I shaved a bit off the forward barrels, about 1/8" total, and added three washers to the aft. This is entirely within common practice for such items, with no effect on strength. I also had to clean up the inside edge of the tabs with an angle grinder to allow the barrel to seat properly.

I have to add, the gear is terrific in changing the character of the aircraft on landing and roll out. Much more yaw stability, and nice absorption of the landing on touchdown.

AVID MK4 582 • $9,500 • AVAILABLE • Needs recover Has grove gear less than 100 ttaf&e CALLS ONLY!!! All other replies wont be answered • Contact Mike Butts - HANGARQUEENS, Owner -  located Plymouth, MA United States • Telephone: 508-496-5394 • Posted October 25, 2019 

2001 AVID FLYER MK IV • $27,500 • YOUR SEARCH IS OVER • 2001 AVID Flyer MK4, Aerobatic Speedwing, grove gear, Kitfox clear bubble doors, wheel pants, go fast, look great, and have fun! The ROTAX 912UL 80 HP and 3 blade ground adjustable prop really pull this 519.5 lb beauty! 1050 gross, picks up more than it's own weight. 26 gallon fuel, 4.5 gallon per hour at 115-120 MPH cruise! Just turned 400 hours engine and airframe. Hoping to sell before January 1st 2020, only has mode C right now and I'm based out of MKE. Lots of recent maintenance including carbs rebuilt and sync, and new "Rotax" rubber parts. • Contact Jeffrey Wisneski, Owner -  located Milwaukee, WI United States • Telephone: 4147324107 • Posted October 28, 2019 

AVID FLYER MK IV N63827 • $17,500 • FOR SALE • Stratus EA-81 Subaru 100HP, 246 hrs. Dual Ignition,3 blade IVO prop. Dual fuel pumps, Grove gear with Hyd. brakes, Electric Trim. Cw builder manual and log book. Located T-25. Flyin and fly it home or trailer it home. Easy storage. Joy to fly. • Contact Mike Denis, Owner -  located Frankston, TX United States • Telephone: 9032793737 • 903-279-3737 • Posted October 30, 2019

Just a Google away:

https://bearhawkaircraft.com/bearhawk-specifications/

I love to see the experienced guys work with kids to share the love of flying. Very cool stuff!

109jb,

You have it backwards, the throat pressure DROPS as the throttle is opened and the velocity in the throat increases.  If you put an artificial low pressure in the float bowl, and the throat pressure is higher (at low throttle), the gas will not leave the bowl and go to the engine.

http://www.ankn.uaf.edu/publications/VS/carburetors.html

I waasn't clear enough. The only reason why gas runs from the bowl to the throat is the difference in pressure of the two air spaces. The throat has low pressure ("suction") so it draws up the gas that the needle allows, an amount regulated by the difference in pressure - the suction - and the size of the hole the needle opens. 

The way the Hacman systems work (because the Bing is a 49c carborator with no leaning capability) is allowing you to change that difference in pressure. Less pressure, by leaking vacuum into the bowl, less gas flows to the throat.

Not exactly. Yes, the vacuum pump holds a constant vacuum, but the thing you want to control is difference between the carb throat pressure and the bowl pressure, not just the vacuum to the bowl. As you reduce throttle, the throat pressure rises (the throat velocity drops with less airflow velocity. I have found with my Hacman that the EGT stays reasonable steady with normal throttle changes, since the balance of throat-bowl pressures is held somewhat constant. 

If the vacuum pump holds low enough pressure, as you reduce throttle is might be possible for the bowl pressure to be lower than the throat pressure, so gas won't flow at all. Then it gets pretty quiet.

Neil,

There were a few nice threads a year or so back about making your own cowl, using foam and glass/epoxy. The craftsmen who did it showed beautiful results, as I recall.