Sign in to follow this  
Followers 0

Avid Model C - Gross Weight

20 posts in this topic

Posted

Hello everyone, this is a strange question. Recently I have had to go through the paperwork of a plane I'm considering purchasing. The Special Certificate of Airworthiness could not be found by the owner, so I reached out to Transport Canada. They advised, there was a Special C of A in place, however they could not find the copy of the document, and hence they went back to the builder. He advised the gross weight was 850 lbs on the placard, however the gross weight could be in the 900 lbs range. The builder ( who is also the seller ) has told me that there should be a way to get the aircraft the higher gross weight. 

So I don't believe everything I always hear, so I'm asking those of you that know, can a Model C Avid with a Speedwing gross weight be changed from 850 lbs to 900 lbs + ?

Thx

 

Share this post


Link to post
Share on other sites

Posted

The paper work I have from the factory says the gross weight on both the commuter and the aerobat are 911, unless you are doing aerobatics in the aerobat and then it's 850.  In the US, the gross weight can be raised by going back into phase 1 flight testing and proving it out.  Don't know about Canada.  JImChuk

Share this post


Link to post
Share on other sites

Posted

Hey Jim, forgive my question, as I don't know a lot about the Avid linage, is the Commuter a Model C with a speedwing?

 

Thx

Share this post


Link to post
Share on other sites

Posted

Sorry, I was digging through some stuff last night looking for that info, and messed up.  The Commuter is a tricycle gear with the short wings.  I'll try digging through some more stuff I have to see if I can find what Avid advertised for the gross weight on a C model speedwing in taildragger form.  JImChuk

Share this post


Link to post
Share on other sites

Posted (edited)

I found this online.

https://avidflyer.fandom.com/wiki/Models

Model C (serial numbers about 250 to about 900)

The Model C's fuel tanks moved to the wings. Matco wheels and hydraulic brakes were used, and a castoring Matco tailwheel with 1-1/4 inch tailspring. The radiator was mounted inside the cowling on the passenger's side. Tubing replaced the wood stringers along the fuselage sides, but a wood stringer was still used on the bottom.

The single diagonal piece of tubing across the cockpit ceiling was changed to a stronger triangular structure.

The Heavy Hauler wing rib spacing was changed to 12 inches. The Aerobat wing had the same features as the Heavy Hauler but was 6 feet shorter (24 feet vs 30 ft). The Commuter wing was a short STOL wing.

Edited by MnAvidFlyer
Link

Share this post


Link to post
Share on other sites

Posted

Thanks Jim - I've heard all kinds of things from a lot of places saying if you add the wing extension kit on the speedwing it increases the max gross weight - I dunno, but right now my model C is serial # 377. It has a max gross weight of 850, usable weight of 400 lbs. I would like to get that up a bit if I could somehow, as it would allow me to have a bit more fuel and two adults for a cross country flight. The plane has the larger fuel tanks, so thats a plus....

But trying to clarify what the gross weight could be and how is really my question , I don't know who would know that now..

.

Share this post


Link to post
Share on other sites

Posted

Got looking a bit more at that info I was referencing last night.  Here it is.  Notice there is an asterisk at speedwing and Commuter.  In the note down on the lower left side of the page (some of the print isn't shown) it says that it can come as a tricycle gear or taildragger.  I would think if you can access that page complete, you may have what you need???  I think I have it somewhere, but didn't find it today when I was looking for it.  Did have the pictures though.  JImChuk

Model_C_p3.jpg

Share this post


Link to post
Share on other sites

Posted

Be most appreciated if you find that page. It looks like gross is 911 lbs, empty is 491 lbs. However I don't know if the aerobat wing is the same as the speed wing, or if it is a different wing all together. That pics shows a trike gear. Essentially I will need some sort of documentation to go back to Transport Canada airworthiness inspector with.

Share this post


Link to post
Share on other sites

Posted

The Aerobat wing is the same as the Speedwing but with thicker wall tube spars and larger diameter lift struts. Here in the United Kingdom the gross weight is 911 lbs which on the Aerobat can be increased to 1020 lbs if stiffeners are fitted to horizontal and vertical tail surfaces.

Ken

Share this post


Link to post
Share on other sites

Posted

The Aerobat wing is the same as the Speedwing but with thicker wall tube spars and larger diameter lift struts. Here in the United Kingdom the gross weight is 911 lbs which on the Aerobat can be increased to 1020 lbs if stiffeners are fitted to horizontal and vertical tail surfaces.

Ken

Also ribs are 18" center on speedwing, 12" center on aerobat.  Both use the flat bottomed rib style. JImChuk

Share this post


Link to post
Share on other sites

Posted

Ah yes forgot that bit Jim!

Share this post


Link to post
Share on other sites

Posted

Just reviewing the numbers under the Speed Wing Commuter Section provided by Jim - I know Transport Canada will ask me what these things mean exactly, since there are no side labels can someone confirm what I am seeing here and fill in errors and all the ???? or the blanks. Really appreciate the help!

..

Length of Aircraft (Nose to tail) - 23ft 11.5 in.

Wing Area = 97.31 sq ft

???? = 42 in

???? = 51 in

???? = 5.50

???? = 9.36 lbs

???? = 17ft

???? = 17ft

???? = 7 ft. 9.5 in

???? = 67 in

Empty Weight = 450 lbs.

Gross Weight = 911 lbs.

Usable Weight = 491 lbs

Fuel Tank Size (single wing tank) = 18 gal

Fuel burn approximate = 3.5 gal/hr (depends on the engine and rpm setting???)

Range no reserve = 566 miles (Statute miles I would think not nautical miles)

Recommended prop??? = 64" ground adjustable (Seems this would depend on the engine?

 

Solo - 580 lbs (why only 580 lbs gross weight when solo???????)

Cruise Speed = 110mph

Stall Speed = 33 mph

Never Exceed Speed = 125 mph

Rate of Climb = 1200 fpm

???? = n/a

Best Rate of climb = 57 mph

Best Angle of climb = 52 mph

???? = 125 ft

???? = 250 ft

???? = 500 ft

Service ceiling ???? = 20000 ft (seems odd - unpressurized cabin)

 

Dual - 911 lbs gross weight

Cruise = 110 mph

Stall Speed = 40 mph

Never Exceed Speed = 125 mph

Rate of Climb (850 fpm)

???? n/a

Best Rate of Climb = 60mph

Best Angle of Climb = 55mph

???? = 300 ft

???? = 500 ft

???? = 600 ft

Service ceiling??? = 15000 ft (seems odd - unpressurized cabin)

Share this post


Link to post
Share on other sites

Posted (edited)

Here is the info on the MK IV stats.  JImChuk

 

MarkIV_Magnum_p2.jpg

Edited by 1avidflyer

Share this post


Link to post
Share on other sites

Posted

Thank you for providing that - any idea why the Solo Gross Weight for a Speedwing is 580 lbs? Why wouldn't it state 1150 lbs pertaining to the MK IV documentation? Empty weight shows 510 lbs, 580 lbs is only 70 lbs more - seems like I would need to lose a lot of weight if I followed those numbers.... =) 

 

Share this post


Link to post
Share on other sites

Posted

Thank you for providing that - any idea why the Solo Gross Weight for a Speedwing is 580 lbs? Why wouldn't it state 1150 lbs pertaining to the MK IV documentation? Empty weight shows 510 lbs, 580 lbs is only 70 lbs more - seems like I would need to lose a lot of weight if I followed those numbers.... =) 

 

this solo 580 number is relative to performance numbers showed under, so customer can have an idea how can perform the plane if he fies solo or dual

Share this post


Link to post
Share on other sites

Posted (edited)

This is all very interesting.  I wonder why the model C (stol) gross weight is only 911 lbs.  Was there additional structure added to the wing for the Mark 4 to bump the gross weight up to 1150 lbs? 

If I only claim 4.4 Gs instead of the 5.7 the original STOL wing was sandbag tested to, I get 1180 lbs for allowable gross.  Maybe the negative G requirement took a 30 lb bite out of this?  No mention has been made to my knowledge of any negative-G testing, though, although you'd think they would want to have done it.

Edited by Turbo

Share this post


Link to post
Share on other sites

Posted

The 1150 lb gross weight Heavy Hauler wings have ribs on 12" centers, and the spars are .083" wall thickness.,  Also lift struts are bigger diameter.  Stol wing rib spacing is 18" and spar wall thickness is .065".  JImChuk

Share this post


Link to post
Share on other sites

Posted

The 1150 lb gross weight Heavy Hauler wings have ribs on 12" centers, and the spars are .083" wall thickness.,  Also lift struts are bigger diameter.  Stol wing rib spacing is 18" and spar wall thickness is .065".  JImChuk

O.K. but the 1150# gross is for the basic Mark 4 STOL, not the HH version (see above).  Like I said, assuming 4.4 Gs instead of 5.7 for the same wing gets you very close to the 1150# gross touted for the Mark 4!  My guess is the negative G requirement bumped it down to 1150# from the 1180# you'd get from just changing the positive G limit.  The bigger lift struts on the HH must be to maintain the negative G limit at the even higher GW of the HH.  It's all about column buckling in the lift struts at negative G.  If there were no structural changes to the basic STOL Mark 4 over the C model, the 1150# gross number should apply to the C model as well.  JimChuk, you're the best historian we've got!  What can you tell us?

Share this post


Link to post
Share on other sites

Posted (edited)

I've never seen or heard of a MK IV that didn't have either a heavy hauler wing, or speed wings.  The C model with heavy hauler wings has a gross weight of 1050 as I remember, but improvements in the fuselage on the MK IV caused it to be raised to 1150. JImChuk 

PS  Avid supposedly eventually said the gross weight was 1200 on the MK IV, but that was probably because Kitfox 4 went with 1200 lb. gross weight and there was competition going on

Edited by 1avidflyer

Share this post


Link to post
Share on other sites

Posted

I've never seen or heard of a MK IV that didn't have either a heavy hauler wing, or speed wings.  The C model with heavy hauler wings has a gross weight of 1050 as I remember, but improvements in the fuselage on the MK IV caused it to be raised to 1150. JImChuk 

Interesting!  Counted cells in the brochure pic above, and yeah, it must be a 12" spacing!  Was thinking of a second wing tank on my C, but it would only be useful when I'm solo.  

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0