Catalina Gross Weight?

[SuberAvid 617]

It is probably posted somewhere on the Forum but I haven't run acrossed it; can someone tell me the gross weight that Avid posted for the Catalina? They made the Amphibian before the Catalina, with some changes such as the sponsons; was there a GW difference between the two? Were there progressive changes in the wing spars and struts over time like with the Flyer?

Any info on this with the specs or a location where I can find the info would be great.

Thanks,

Randy

[akflyer 1427]

Gross weight is 1200, WS is 36'. It has the same spars as the HH and same rib spacing if I remember correctly. I think the Anfib and catalina both have the same gross and wing, changes were to sponsons on the struts versus wing tips etc.

http://www.seaplanes.org/index.php?option=com_content&task=view&id=331&Itemid=339

[SuberAvid 617]

Thanks Leni. You got the wheels turning now; just tryignt to figure out my options. I was hoping for a 1300 lb GW but no such luck. Also kind of suprised at the 90 mph Vne. I think the Airdale wing might be something in between the HH wing and the Cat wing for length, and I think has a 1400 lb GW. I probnably need to give Brett a call.

Randy

[C5Engineer 1170]

Thanks Leni. You got the wheels turning now; just tryignt to figure out my options. I was hoping for a 1300 lb GW but no such luck. Also kind of suprised at the 90 mph Vne. I think the Airdale wing might be something in between the HH wing and the Cat wing for length, and I think has a 1400 lb GW. I probnably need to give Brett a call.

Randy

The original VNE's were really low I think because of the glued on fabric. I'm assuming your stitching? There are 912 and Jab guys cruising at the 115mph range with the early models.

[akflyer 1427]

The original VNE's were really low I think because of the glued on fabric. I'm assuming your stitching? There are 912 and Jab guys cruising at the 115mph range with the early models.

Most things I have read were in line with what Joey said. VNE was due to no rib stitching, and over the evolution, I belive the VNE was increased to 125 or 130 with rib stitching. I have had mine to 125 and nothing ripped off, but the flapperons were pretty heavy feeling

I do 110 descents all the time.

I also think the 1200 was more what the hull would float safely than a wing issue. It sounds like at 1200 you are sitting pretty low in the water and get some pretty good splashing. I would not be afraid to go up to 1320 but would probably not be trying to do any snaps or spins with it at the full 1320

[dholly 718]

Thanks Leni. You got the wheels turning now; just tryignt to figure out my options. I was hoping for a 1300 lb GW but no such luck. Also kind of suprised at the 90 mph Vne. I think the Airdale wing might be something in between the HH wing and the Cat wing for length, and I think has a 1400 lb GW. I probnably need to give Brett a call.

Randy

Randy,

It is my understanding the Airdale uses the same 144"L x .083" wall T6061 spars as our Mk-IV HH and Avid+. After a lot of time researching this, I came to the conclusion that building new Airdale or Magnum wings for my Avid+ was alot of wasted time and expense. According to Steve W., the Airdale wings use steel vs. alum drag tubes w/gussets for the higher compressive loads, along with 1" x .049 wall 4130 lift struts and an aluminum spar stiffener identical to the original Magnum, which was similar in shape to the plywood MkIV HH stiffener but longer. Of course, there are other airframe and gear modifications inherent to the Airdale that together add up to the 1400#, which we cannot retrofit. What I did do in my own quest for increased mtow was modify my stiffeners. Here's an excerpt from my log explaining my rationale:

The kit manufacturer's suggested gross weight rating for my old Avid Mk-IV with Heavy Hauler wing (144"L x .083" wall T6061 spars, 7/8" x .035" wall 4130 lift struts, aluminum drag tubes, ribs 12" o.c. and 1/4" x 16" ply spar stiffeners) was 1200lbs. By comparison, the suggested gross of the Avid+ with the exact same wing, excepting 1/4" x 18" ply wing spar stiffeners, is 1250lb., due primarily to a stronger fuselage. I decided to replace the 1/4" x 18" ply wing spar stiffeners supplied with the Avid+ kit (part W-24, inserted into the spars and secured under the lift strut brackets) in favor of a longer, stronger spar stiffener design similar to that used in the Avid Magnum. My goal in doing so is to safely increase useful load by an additional 70lbs, to the Light Sport Aircraft max of 1320lbs.

The rationale... early Avid Magnum design at 1500lbs. gross, used identical 0.83" spars and ribs, but added 1" x .049 wall 4130 lift struts, steel drag tubes (vs. aluminum) and 1/4" x 24" long ply stiffeners. Shortly afterward, Magnum gwt was increased to 1650lbs. with the addition of 1/8" x 24" aluminum stiffeners similar in shape/size as the original plywood type, however, two strips of 1/8" x 1/2" aluminum were riveted along the top edge of the aluminum stiffener to form a kind of 'T-Beam'. All other wing components being equal, the new stiffener allowed for a 150lb. (10%) gwt. increase according to the kit manufacturer. Even later, gwt was raised to 1750lbs. with the addition of a 36" extruded aluminum 'I-Beam' stiffener. So obviously, adding beefed-up 'Magnum style' spar stiffeners will strengthen the Avid+ wing. Since 70lbs. would represent a 5.6% increase in gwt for the Avid+... about one-half the 10% factory increase on the Magnum for essentially the same stiffener modification... I do not think the possibility of raising my gwt by 70lbs. after the stiffener mod is either unfounded or dangerously unrealistic.

However, I am mindful there are several other areas in the wing that run out of 'stress related' safety factor margin over 1250lbs that must be considered as well, ie., Heim adjustable rod end, rod end attach bolts, rod end welded screw thread, the root attach bolt and bushings, the wing attach bolts, the lift strut attach brackets and the carry through tubes. Further, the wing and related components are only one small part of the gross operating load capacity equation and there are many other inter-related items to take into consideration. Landing gear, bungees, tailwheel, tailspring, attach bushings, attach bolts, wheels, brakes, axles, fuselage tube i.d. and o.d., bigger rudder, larger elevator, trim tab requirement, heavier duty fabric etc., all come into play.

To be conservative and safe, I will do calculations on the wing loading and consult the G forces per bank angle charts. For a slightly higher useful load, I would limit operation in turbulence and keep bank angles below 75*-80* degrees (probably not a huge problem with amphib floats hanging under!), if necessary. At 1320lbs. gwt., useful load with pilot, passenger and gear would increase from 450lbs. to 520lbs. (or from 300lbs. to 370lbs. with full fuel, and from 375lbs. to 445lbs. with half fuel) on the amphib floats. In any event, this will be a good 'weight for safety' trade off. At 4.2ozs. for the original W-24 ply vs. 17.5ozs. each for my new wooden 'I-Beam' stiffeners, the weight penalty is 13.3oz. each x (4) stiffeners = 53.2ozs., or about 3-1/3lbs. total. One other alternative: adding a 12" length of hardwood shoe mold to both sides top and bottom of the supplied W-24 stiffener. This weighs out at 10.3ozs. each, or a total weight penalty of ~1-1/2lbs. total.

Of course YMMV but, along with the foregoing armchair engineering, I think the Avid wing load test results and long history of all those Avids and Kitfoxes flying 70lbs heavy regularly lead me to feel comfortable with a mtow between 1250 and 1320 after simply modifying the stiffener. Since I made mine, I heard Just Aircraft came out with an extruded aluminum 'I'-Beam style stiffener that fits the I.D. of the .083 spar, might be worth a call.

Cheers,

Doug

[akflyer 1427]

Randy,

It is my understanding the Airdale uses the same 144"L x .083" wall T6061 spars as our Mk-IV HH and Avid+. After a lot of time researching this, I came to the conclusion that building new Airdale or Magnum wings for my Avid+ was alot of wasted time and expense. According to Steve W., the Airdale wings use steel vs. alum drag tubes w/gussets for the higher compressive loads, along with 1" x .049 wall 4130 lift struts and an aluminum spar stiffener identical to the original Magnum, which was similar in shape to the plywood MkIV HH stiffener but longer. Of course, there are other airframe and gear modifications inherent to the Airdale that together add up to the 1400#, which we cannot retrofit. What I did do in my own quest for increased mtow was modify my stiffeners. Here's an excerpt from my log explaining my rationale:

The kit manufacturer's suggested gross weight rating for my old Avid Mk-IV with Heavy Hauler wing (144"L x .083" wall T6061 spars, 7/8" x .035" wall 4130 lift struts, aluminum drag tubes, ribs 12" o.c. and 1/4" x 16" ply spar stiffeners) was 1200lbs. By comparison, the suggested gross of the Avid+ with the exact same wing, excepting 1/4" x 18" ply wing spar stiffeners, is 1250lb., due primarily to a stronger fuselage. I decided to replace the 1/4" x 18" ply wing spar stiffeners supplied with the Avid+ kit (part W-24, inserted into the spars and secured under the lift strut brackets) in favor of a longer, stronger spar stiffener design similar to that used in the Avid Magnum. My goal in doing so is to safely increase useful load by an additional 70lbs, to the Light Sport Aircraft max of 1320lbs.

The rationale... early Avid Magnum design at 1500lbs. gross, used identical 0.83" spars and ribs, but added 1" x .049 wall 4130 lift struts, steel drag tubes (vs. aluminum) and 1/4" x 24" long ply stiffeners. Shortly afterward, Magnum gwt was increased to 1650lbs. with the addition of 1/8" x 24" aluminum stiffeners similar in shape/size as the original plywood type, however, two strips of 1/8" x 1/2" aluminum were riveted along the top edge of the aluminum stiffener to form a kind of 'T-Beam'. All other wing components being equal, the new stiffener allowed for a 150lb. (10%) gwt. increase according to the kit manufacturer. Even later, gwt was raised to 1750lbs. with the addition of a 36" extruded aluminum 'I-Beam' stiffener. So obviously, adding beefed-up 'Magnum style' spar stiffeners will strengthen the Avid+ wing. Since 70lbs. would represent a 5.6% increase in gwt for the Avid+... about one-half the 10% factory increase on the Magnum for essentially the same stiffener modification... I do not think the possibility of raising my gwt by 70lbs. after the stiffener mod is either unfounded or dangerously unrealistic.

However, I am mindful there are several other areas in the wing that run out of 'stress related' safety factor margin over 1250lbs that must be considered as well, ie., Heim adjustable rod end, rod end attach bolts, rod end welded screw thread, the root attach bolt and bushings, the wing attach bolts, the lift strut attach brackets and the carry through tubes. Further, the wing and related components are only one small part of the gross operating load capacity equation and there are many other inter-related items to take into consideration. Landing gear, bungees, tailwheel, tailspring, attach bushings, attach bolts, wheels, brakes, axles, fuselage tube i.d. and o.d., bigger rudder, larger elevator, trim tab requirement, heavier duty fabric etc., all come into play.

To be conservative and safe, I will do calculations on the wing loading and consult the G forces per bank angle charts. For a slightly higher useful load, I would limit operation in turbulence and keep bank angles below 75*-80* degrees (probably not a huge problem with amphib floats hanging under!), if necessary. At 1320lbs. gwt., useful load with pilot, passenger and gear would increase from 450lbs. to 520lbs. (or from 300lbs. to 370lbs. with full fuel, and from 375lbs. to 445lbs. with half fuel) on the amphib floats. In any event, this will be a good 'weight for safety' trade off. At 4.2ozs. for the original W-24 ply vs. 17.5ozs. each for my new wooden 'I-Beam' stiffeners, the weight penalty is 13.3oz. each x (4) stiffeners = 53.2ozs., or about 3-1/3lbs. total. One other alternative: adding a 12" length of hardwood shoe mold to both sides top and bottom of the supplied W-24 stiffener. This weighs out at 10.3ozs. each, or a total weight penalty of ~1-1/2lbs. total.

Of course YMMV but, along with the foregoing armchair engineering, I think the Avid wing load test results and long history of all those Avids and Kitfoxes flying 70lbs heavy regularly lead me to feel comfortable with a mtow between 1250 and 1320 after simply modifying the stiffener. Since I made mine, I heard Just Aircraft came out with an extruded aluminum 'I'-Beam style stiffener that fits the I.D. of the .083 spar, might be worth a call.

Cheers,

Doug

Doug, the thought was the catalina wing is longer... and would be better for the heavier fat bastards.... in fact, I want to build plug in tips for mine to extend them out. Would be nothing to whip up a longer set of struts etc. to make them the same length as the catalina... more wing is more lift, is slower flight for me... I like getting in and out short, especially on floats

[dholly 718]

Leni, I guess I look at the 'more mtow' vs. 'more lift' as being two separate goals. I remember Steve W saying on the other site it was ok to add tip extensions to HH wings without moving the wing strut attach brackets out or going to longer 1" struts like the Magnum, but I always just assumed it was to gain more lift not increase mtow. Maybe he's right there is enough stress safety factor built in to counter extra weight or any adverse change in bending moments or g load due to the unchanged lift strut position. Personally, I would be uncomfortable with that if I was placing a lot of stress on my plane/wings plopping in and yanking out of tight AK gravel bars like you guys do. In any event, if the Cat wings are rated for 1200# adding them to a 1200# or lighter Avid, particularly if floated, might be worth it for extra lift but fitting them to a 1250# Avid+ would cost Randy and me 50# mtow. I'd probably shy away from using the Cat lift struts too. IIRC, they use 7/8" x .035 wall 4130 lift struts with 2 jury struts because they failed at 1150# gross with only one. The 1" x .049 wall 4130 lift and single jury strut used on the Airdale and Magnum sound stronger and less draggy too. Either way, extending HH wings using existing struts/brackets or adding longer Cat wings may get you more lift from the larger wing surface, but how much of the gain in lift performance will be offset by the added weight? I'm not suggesting it is a show-stopper, I have no idea, but would definitely be interesting to find out. You've done crazier things, go for it!

[akflyer 1427]

hmmm didnt think about just extending my wings and not the struts. when I made new struts for mine I used 1" X .059" tubing. hmmm now you have me thinking about just making extensions for mine and moving the flaperons out to the end. I sure wish Steve would show up on the lists again and give us some words of wisdom.

How is your build coming along? updates have not been real stellar from the chunky avid club lately

[dholly 718]

Leni, if you already have the .083 spars w/ ribs 12"o.c., with your beefed lift struts it certainly sounds to me like simply adding an extra bay or two is the way to go. The only question left is with the greater bending moments etc, so it seems the brackets and adjustable lift strut end become the point of failure weak links. Did you use the standard ply stiffener or did you beef those too? Remember, the HH wing was stress tested and passed even without the original oem stiffener but, IMHO, you would be wise to strengthen the bracket area if you add wing area. Two additional bays on a HH wing adds, what, almost 15-20% surface? That seems like it would put the wing a long ways out of original design stress specs to me and the bending is what causes risers so the more you can do to stiffen the wing the better, right? You can see from the Magnum stiffener history that a relatively simple change can make a huge difference there. Just a though but that said, since Avid/Airdale actually did/do offer a wing extension kit, I suspect someone with more than an armchair aeronautical engineering background passed off on it so maybe we are all over thinking it. One thing for certain, washout adds up fast on a longer than norm wing if you used 2" twist per the manual. Have read that creates real issues w/ speed wing regarding more loss of top speed than lift created but I assume much less of a problem with the under camber ribs.

BTW, there is a new Catalina listing on Barnstormers in the past day or so if anyone is looking. Location was Maine I think, looked clean w/ very low time 582...