What changes allowed 1100#-1150#-1200#

[Howard Wilson]

Did the search thing. Could have missed it. What were the physical changes made at the factory or later that allowed the GW increase from 1100# to 1150# to 1200#? Thanks. Howard

[1938BF50]

Re: What changes allowed 1100#-1150#-1200#

Howard,

I THINK the change from 1100 to 1150 was just a HP increase. Not sure exactly when the wings went from 13 rib to 15 rib (1940?) but this may have had an effect too. Hopefully, someone more knowledgeable than I will pipe up. The latest paperwork for my '38 lists my gross at 1250#, which is obviously a mistake.

[Ragwing nut]

Re: What changes allowed 1100#-1150#-1200#

13 rib to 15 rib gave the 1200 lb increase. That was done with the '41 DeLuxe. Only prewar to have 15 ribs and 1200 lb gross. Not sure about the other changes

Mike

[Forrest Barber]

Re: What changes allowed 1100#-1150#-1200#

The changes are on the ATC. They indicate what drawings need to be checked for the changes. Basically , 1100 to 1150 tubes in fuselage, 1150 to 1200 wings ....

[VictorBravo]

Re: What changes allowed 1100#-1150#-1200#

The changes are on the ATC. They indicate what drawings need to be checked for the changes. Basically , 1100 to 1150 tubes in fuselage, 1150 to 1200 wings ....

So does that mean that the Harer STC upgrade I did on my 1940 BC-65 does or does not allow me to fly at 1280 pounds gross (short mount, small baggage)?

I have built-up ribs and pre-1941 wings. I don't know which tubes in the fuselage to check either.

The STC says I can go to 1280, so it is probably legal... But if I don't have certain tubes or ribs to get from 1100 to 1150 on the type certificate... then do I have enough structure to go to 1280 as part of the STC?

[Howard Wilson]

Re: What changes allowed 1100#-1150#-1200#

Forrest,

What tubes do those drawings indicate were added or beefed up for the 1100# to the 1150? What should I be looking for? A fuselage carry through from strut to strut? Bill's situation was just what I was thinking about. If I put on 15 rib wings without bolstering the fuselage tubes I'm still at 1100# GW, not 1200# right? Thanks. Howard

[Howard Wilson]

Re: What changes allowed 1100#-1150#-1200#

One of the fellows on the list suggested that the fuselage tubes that were (added/ reinforced?), were up front to reinforce the areas stressed by the increase in engine power. Diagonals, gussets??? Does anyone know at which SN the change occurred?

[Ragwing nut]

Re: What changes allowed 1100#-1150#-1200#

The only change I know of in the fuselage besides the postwars being 4130, is that the wing attach fittings on the fuselage are gusseted.

Mike

[Guest]

Re: What changes allowed 1100#-1150#-1200#

So does that mean that the Harer STC upgrade I did on my 1940 BC-65 does or does not allow me to fly at 1280 pounds gross (short mount, small baggage)?
I have built-up ribs and pre-1941 wings. I don't know which tubes in the fuselage to check either.

The STC says I can go to 1280, so it is probably legal... But if I don't have certain tubes or ribs to get from 1100 to 1150 on the type certificate... then do I have enough structure to go to 1280 as part of the STC?

Hi Bill,

I think ya gota go with the STC and it says 1280 if you make the mods.

So there it is. I would believe the STC.

Dave

[VictorBravo]

Re: What changes allowed 1100#-1150#-1200#

Hi Bill,

I think ya gota go with the STC and it says 1280 if you make the mods.

So there it is. I would believe the STC.

Dave

Sure it's legal at 1280 because the PAPER says so. I don't always live by the paper when it tells me not to do something, so by all rights I should have to not automatically believe it when it says I can do something!

I'm not the least bit concerned with the paper on this issue just yet... My question is actually whether there are enough tubes or pieces of metal to support that weight from a structural point of view. If there is not enough structure on my airplane to support the change from 1100 to 1150, how can there be enough structure to support a weight of a 1280 pound airplane... or a 1500 pound airplane if I put the long engine mount on?

I think I'll build me a Titanium Taylorcraft... oh, wait a minute... I can't weld

[NC36061]

Re: What changes allowed 1100#-1150#-1200#

I think you are onto something there, Bill. If C.G. and the CAA decided in 1941 that 15 ribs per wing and other changes in structure and material (switch to 4130 steel, etc) were required to increase g.w. to 1200lbs, how can an STC that does NOT require the same changes safely allow you to go to 1280 lbs gross?? Maybe its not UNsafe, maybe the original changes were unnecessary or overkill, but how do you know? I'm sure the changes done by the factory in 1941 were not merely arbitrary guesses about appropriate structural improvements. It doesn't add up that the STC for a subsequent increase in g.w. conflicts with the Type Certificate for a factory-built airplane of approximately the same g.w. It looks to me like this is something that slipped past CAA or FAA when the STC was approved. Just my impression.

Dave

[Guest]

Re: What changes allowed 1100#-1150#-1200#

Bill & Dave,

I am not saying its load carry capacity is correct merely because of a piece of paper. I am not that stupid.

I am saying that because I have talked with Harer and I have read some of Gilberti's work.

They are two sharp cookies. I do not believe that issue would have gotten past either of them. If in fact it is an issue at all.

I am saying that because I don't think they would have made that mistake.

The acid test would be to call Mr. Harer and ask him what he thinks.

Dave

[Guest]

Re: What changes allowed 1100#-1150#-1200#

Just as a reminder, when the experts on this forum contended that the hole in tail post should have been plugged but had note or wasn't supposed to be there at all. Harer new all about it and told me immediately without a moments hesitation.

Later Forrest said he founs something like 1/2 the fuselages he looekd at had that hole.

Harer is a sharp guy. Give him a call. I bet you will be very happy with the result.

[VictorBravo]

Re: What changes allowed 1100#-1150#-1200#

Bill & Dave,

I am not saying its load carry capacity is correct merely because of a piece of paper. I am not that stupid.

Dave

I would never say you're stupid, Dave. Not by a country mile. I was poking some fun at the relationship (or lack thereof) between what is safe and what the paperwork says... both ways.

I have spoken with Bob Harer a couple of years ago about something else, and on the day I spoke to him he was either not on his best game, or something was purposely not being said.

Gilberti may have been a sharp guy, but some of the things I've seen that have his name associated with them are pretty confusing, either un-intentionally or otherwise.

But I'm sure most of the group would not ever want me to get off on THAT tangent again!

[Guest]

Re: What changes allowed 1100#-1150#-1200#

Hi Bill,

Mr. Harer has a disease that effects his speech (but that's all) so there are periods of silence when you talk with him.

It does appear that some days are better than others.

Give him a second try.

I plan to call him this week on another matter, could pass your question on if you like.

Dave