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Mk4 Gross weight

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Posted

I'm not real familiar with Avids but have been asked to have a look at one  for a potential purchaser.

the c/n is 1206c  this Is listed as a heavy hauler. From what I can see from researching this forum is,to be a Heavy hauler the c/n has to end with a c? The ribs need to be 12 inches apart and spar wall at .83

The gross weight  for a HH should be 1150 pound?Is there anything else I should be looking for ,have I got my facts right?   

Cheers

Dusty

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Posted (edited)

I'm not real familiar with Avids but have been asked to have a look at one  for a potential purchaser.

the c/n is 1206c  this Is listed as a heavy hauler. From what I can see from researching this forum is,to be a Heavy hauler the c/n has to end with a c? The ribs need to be 12 inches apart and spar wall at .83

The gross weight  for a HH should be 1150 pound?Is there anything else I should be looking for ,have I got my facts right?   

Cheers

Dusty

Yes Dusty,  HH is 12" and .083.  Could also be 1200 GW - some were.  1206c sounds like C model to me, but Avid guys should know more?  The MkIV numbers may have started lower than that one?   I only answered this because 99% of the Avid Flyers on this side of the planet are probably sleeping now.  It's 4 AM in Missouri and 2 AM in California.

A MkIV  could also be STOL with wider rib spacing and .065" spars, or an HH, with 29' 10" approximate wings with undercambered ribs like Kitfox and  no side radiator scoop on cowl.  (I just learned that from reading)  I put AVID Specs in Files and Forms which covers all Avid models, and you will find more info there - the best is probably what C5Engineer posted with Doug Holly's info in "Avid Wing Technical Data".  Other than that, just look at it the same as you would look at a Kitfox, and you know about them.   Oh, if it's a 2-smoke, the sparkplugs will point down!  ;<)  Cheers,  EDMO

Edited by EDMO

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Posted

Supposedly, the MK IV serial # should start around 1000.  They end in a D though, not a C.  Is that a misprint?  MK IV also have a baggage compartment, and a rounded tail.  JImChuk

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Posted

It it truly is a C on the serial number then it's a number that someone made up when they did the paperwork. You can make that part whatever you feel like during the process. The Heavy Hauler wings and spars only had minor changes over the years such as the solid leading and trailing edges. Many people slapped a MK4 cowl set up and tailfeathers on B models and called them a MK4 which is NOT the case. The true MK4's had a lot of other subtle changes to them mainly in the fuse to increase the Gross Weight. The changes are laid out pretty clearly in Dougs Post. I see a lot of potential buyers getting wrapped up on the gross weight. In 9 years and 500 hrs I've flown my airplane at gross twice. With a 582 at gross in any kind of elevation they are pretty weak in the power dept.

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Posted

I see this aircraft listed as a STOL,so assuming 1150 pound ?it should have storage behind the seat?

there are some images online (ZK JFR)if that is any help.

max weight is a consideration as we usually  fly heavy and can have some savage turbulence (no one likes g meters here :bugeyes:)

i hope hope to get a look later this week.

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Posted

I see the baggage door behind the seat.  I think I counted enough ribs to make it a HH but not sure, the eyes are crappy and my glasses are at home :lol:

If the turbulence gets too bad pull the power back and slow her down a bit. 

:BC:

 

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Posted (edited)

Some people use STOL for anything they want to sell - Some use it for undercambered wings - Avid used it for the .065 spars with 15/16" rib spacing compared to the HH with .083 and 12" - The HH could also be considered as a STOL by someone selling a plane, but not by Avid standards.  Check it closely - could also be a 1200 GW, but what difference does 50 lbs make?  These birds are built somewhere around 150% of GW for safety reasons. 

As Leni said, "If you are in rough air, throttle back and slow down" - If you want to go into physics, then a heavier bird will take more turbulence than a light one - I know that don't make sense to the average person, but it has been shown to be true by those who can explain it better than me.  It has more to do with how fast the bird goes up and down in rough air.   EDMO

Edited by EDMO
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Posted

Spot on Ed. The higher the wing loading, the less you'll be tossed around in rough air

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Posted

Dusty - the term 'heavy hauler' is used very haphazardly, be careful. It originally was meant as a description for a particular wing construction and lift strut combination, not a particular model Avid, MTOW or gross. Even though it was introduced with the C model, that HH wing/strut combo could be placed on any Avid Flyer model A-E as each shared the same 27-1/2" wide f/r spar bushing spread and strut attach bracket location.

Therefore, it is possible to have a Mk-IV Heavy Hauler, or an Avid C model Heavy Hauler, or an Avid B model Heavy Hauler etc. Although each may have different gross weight ratings due to model, and even due to wing/lift strut combination within the same model. So, just like you must check the Mk-IV characteristic check list to verify a fuse is a true Mk-IV 1159 lb. gross fuse, you must verify that each of the individual wing/ strut components that make up the HH wing designation are present to confirm the plane you are looking at is a true Avid Mk-IV HH.

In addition to the 'How to tell if it's a true Mk-IV', I also posted a detailed description of the Avid HH/STOL/Speed/Aerobat wing/strut differences. Now here's some additional info from a trusted factory source necessary to understand the various Avid model history. Info copied from thread HERE.

Some Lift Struts 4130 details

Avid A, B,C, & Bandit--STOL Versions NOT Hauler used 3/4" .035 wall 4130---gross weight around 1000lbs.

Avid B,C Speedwings, NOT Aerobatic, used 3/4" .035 wall 4130

Avid B,C, D MkIV Hauler used 7/8" .035 wall 4130 Gross weight around 1200lbs

Avid Magnum used 1" x .049 wall 4130. Gross weight 1500-1750lbs depending on who's selling it and where to? Longer lift struts than Flyer

Airdale uses 1" .049 wall 4130. Gross weight of 1400lbs with a Magnum style adjustable rod end. Same length as Flyer.

Avid Amphib /Catalina used 7/8" .035 wall 4130 with 2 Jury Struts, (AD compliance, as they failed in -ve at 1150lbs gross!) Longest lift struts.

These details could be used as a quick check to see what gross weight capability on a used airplane / kit etc...there are many mixed and matched variations out there.

Regards,

Steve ukav8r at Airdale.

 

The Heavy Hauler was the name attached to several Avid models. A Heavy Hauler B or C model was 1050lbs. A Heavy Hauler MkIV was originally 1150lbs and then, to compete with the Kitfox 1200, "re-marketed" as 1200lbs. When Airdale sold upgrades from an Avid to an Airdale or a "FatAvid" they clearly stated that the gross weight of the upgraded model was as per the existing wing construction. The Airdale airframe, Landing Gear, Tailwheel, was designed for 1400lbs gross weight. The Avid+ or "FatAvid" Frame etc. was designed for a gross weight of 1250lbs. Fit a STOL wing from A model and gross weight would be 850lbs, Wing from Avid B/C model 1050lbs, Avid MkIV HH 1150-1200lbs. STOL wing from Avid MkIV / Bandit 911lbs-1000lbs. Gross weight increase is not just about the wing. There are many inter-related other things to take into consideration. Landing Gear, Bungees, Tailwheel, Tailspring, Attach bushings, attach bolts, Wheels, Brakes, Axles, Carry through tubes. Even to the extent of Bigger Rudder, larger elevator, trim tab requirement, heavier duty fabric etc... BUT as the builder of an experimental becomes the "designer" ANY gross weight can be stipulated prior to flight testing, provided it could be "shown" to have been demonstrated. This is the reason I said one has to be careful around gross weights and Wings.....the wing is only 1 small part of the equation. You can see similar changes around gross weight and airframe / wings etc with the Kitfox models.... and I hate to admit it But.... they were a bit more scientific about it. Regards, Steve

 

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Posted (edited)

Some people use STOL for anything they want to sell - Some use it for undercambered wings - Avid used it for the .065 spars with 15/16" rib spacing compared to the HH with .083 and 12" - The HH could also be considered as a STOL by someone selling a plane, but not by Avid standards.  Check it closely - could also be a 1200 GW, but what difference does 50 lbs make?  These birds are built somewhere around 150% of GW for safety reasons. 

15/16th rib spacing? Whaaaa... :o

STOL wing used 18" o.c. rib spacing.

Please see: http://www.avidfoxflyers.com/index.php?/topic/2095-avid-wing-technical-data/

Edited by dholly

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Posted (edited)

Some people use STOL for anything they want to sell - Some use it for undercambered wings - Avid used it for the .065 spars with 15/16" rib spacing compared to the HH with .083 and 12" - The HH could also be considered as a STOL by someone selling a plane, but not by Avid standards.  Check it closely - could also be a 1200 GW, but what difference does 50 lbs make?  These birds are built somewhere around 150% of GW for safety reasons. 

As Leni said, "If you are in rough air, throttle back and slow down" - If you want to go into physics, then a heavier bird will take more turbulence than a light one - I know that don't make sense to the average person, but it has been shown to be true by those who can explain it better than me.  It has more to do with how fast the bird goes up and down in rough air.   EDMO

15/16th rib spacing? Whaaaa... :o

STOL wing used 18" o.c. Rib spacing. Please see: http://www.avidfoxflyers.com/index.php?/topic/2095-avid-wing-technical-data/

As usual, you are correct Doug - I guess I had a brain fart while typing, or wife must have said something to distract me, or dog barked?  What can I say?  18" rib centers for Avid STOL, and all Kitfoxes 1-4.  :BC:  EDMO

Edited by EDMO

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Posted

No biggie Ed, got a good chuckle out of that 15/16. I figured I better clarify as poor Dusty is probably already confused enough, lol.

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Posted (edited)

No biggie Ed, got a good chuckle out of that 15/16. I figured I better clarify as poor Dusty is probably already confused enough, lol.

No worry Doug, and I think maybe in Dustyland they measure in Kilos or some silly "moon-distance" measurement, which turned out to be incorrect?  How did descendants of King Artherland ever get so divided? (The Russians and Trump did it!)  ???  Just kidding Dusty - How many "Stones" does your bird weigh?  Ha!  EDMO

Edited by EDMO
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Posted

Confused, yup:blink: I'm also having to convert Stone Age pounds to 20th century metrics:flamegun:

1150 is ok but 1200 would be better .thanks for all the help guys.Slowing  down In turbulence (and having full tanks)is always a good idea it's the occasional clear air nose bleed slam that's the worry.

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Posted

Pounds, KGs...  I get these.  I don't like it, the communist metric BS, but I get it.  :flamegun::flamegun:

 

Then WTF is the weight measurement "stone" I keep seeing?  Where the hell did that come from???

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Posted (edited)

Larry,

Stone is an old English measurement used for weight - a man weighs x many stones, and was x axe handles tall - I think a stone weighed about 16 or 16 1/2 pounds?   That may also be the weight of the stone they use in Curling games?

A horse was so many "hands" tall.  ???   A rod is about 16 1/2? feet long. 

A cubit was the length of an arm from elbow to fingers - how is that for accuracy for building an Ark !  ;<)

And now I have to use a caliper that reads both in inches and sillymeters, and keep two sets of wrenches in my truck!

"Old English" EDMO

Edited by EDMO

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Posted

Ed, you are close. A Stone is 14 pounds. We changed to metric measurements in the 60's and 70's. Fishermen and young Mothers still tend to use Imperial to brag about their latest catch/ addition to the family. A 10 pound New Zealand Brown Trout sounds better than the same fish weighing 4.54 kilograms!!    

Happy Thanksgiving to you all.

Ian

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Posted (edited)

Ed, you are close. A Stone is 14 pounds. We changed to metric measurements in the 60's and 70's. Fishermen and young Mothers still tend to use Imperial to brag about their latest catch/ addition to the family. A 10 pound New Zealand Brown Trout sounds better than the same fish weighing 4.54 kilograms!!    

Happy Thanksgiving to you all.

Ian

10 pound Brown trout!  Small by Canadian and Alaska standards, but huge here - My sister-in-law and her husband go trout fishing a lot - they weigh their tiny trout in ounces - guess that is something in minikilos!  ;<)    Is that the same weight stone as in Curling?  Happy Thanksgiving Turkey Day.  Maybe you have Trout instead?  My Thanksgiving meal used to be Alaska King Crab legs, Gulf of Mexico Shrimp, Beer-battered Halibut and Scallops.   I was very Thankful to get to live in Alaska for about 11 years!  EDMO

Edited by EDMO

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Posted

We flew up to have a look at this avid the other day.It has 12inch spacing on the ribs 7/8 lift struts,the elevator has been fitted with a inset elevator and still has the sling seat.

My main concern is a bracket for the oil tank piping that is riveted to the lower carry through,is this acceptable and normal?

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Posted

That is per plans.

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Posted

Some people use STOL for anything they want to sell - Some use it for undercambered wings - Avid used it for the .065 spars with 15/16" rib spacing compared to the HH with .083 and 12" - The HH could also be considered as a STOL by someone selling a plane, but not by Avid standards.  Check it closely - could also be a 1200 GW, but what difference does 50 lbs make?  These birds are built somewhere around 150% of GW for safety reasons. 

As Leni said, "If you are in rough air, throttle back and slow down" - If you want to go into physics, then a heavier bird will take more turbulence than a light one - I know that don't make sense to the average person, but it has been shown to be true by those who can explain it better than me.  It has more to do with how fast the bird goes up and down in rough air.   EDMO

Maneuvering speed (turbulent air speed) goes up with gross weight for a simple reason.  It is the speed at which the airfoil will stall before it is accelerated beyond its limits.   Heavier planes stall at higher speeds than light ones if the wing/airfoil is the same.  I was always trying to wrap my head around inertia as a reason, but I found a good explanation of it a while back.

Mark

 

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Posted

Let me weigh in:  It is safer to stall and spin (then recover) then it is to suffer a structural break up. At higher weights, the wing lift at speed makes lower load factor (lower "G") so the aircraft is much less likely to break apart. The load factor is the ratio of the wing lift to the gross weight.  At light weight, the wing lift at stall (the exact same lift as the heavy weight case) makes much higher load factor so the aircraft might break up before it stalls.

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Posted (edited)

Let me weigh in:  It is safer to stall and spin (then recover) then it is to suffer a structural break up. At higher weights, the wing lift at speed makes lower load factor (lower "G") so the aircraft is much less likely to break apart. The load factor is the ratio of the wing lift to the gross weight.  At light weight, the wing lift at stall (the exact same lift as the heavy weight case) makes much higher load factor so the aircraft might break up before it stalls.

I will add this:  I believe the "stall" is not like the intentional stall and recovery a pilot might do - rather, it is a short cycle of stall and recovery that the plane does - happening in the middle of severe bumpy turbulence, and maybe not even recognized by the pilot.  EDMO

Edited by EDMO

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