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Bigger door

D.A.

FRIEND
Free America
I have a Tango Cub and I'm thinking of making the lower door larger (Longer) like the Carbon Cubs and C model Huskys. If I do I'll be going into Experimental for that and other reasons, but I still want to be safe regardless of EXP. I've heard one of the fuselage builders does this mod "All the time" and I'm wondering if anyone else has looked into this from a structural standpoint. There are 2 tubes that go from the lower aft corners of the windshield tubing cluster down to the gear mounts. The original way is to have the aft tube (Which goes to the rear gear fitting) form the front off the door. The extended doors go all the way forward to the forward tube, cutting the aft tube off short at the bottom of the door. Sorry of that was hard to follow - LOL. Has anyone looked into this? Can you just cut the aft tube off at the lower door cut out and extend the lower door to the forward tube without any other modification on an existing frame? Thanks in advance.
 
Javron other door
That's EXACTLY what I'm taking about. Being old and about as flexible as a cinder block, that little extra area area of the door would really help out. Without that triangle removed, that's right where my heels hit. From the pictures I've seen, the only added structure I can see is an additional tube creating an "A" truss under the door. If you did that with an original frame, the angles would be a little different, but that's what I'd like to do. Has anyone done that to an original fuselage?
 
Here's a photo showing the Javron modified door without fabric on. If you want photos from any other angles for reference let me know and I'll take some for you.
20240122_221120.jpg
 

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Having flown some Huskys with the larger door, I can tell you that this is a brilliant move. As we age, sliding in and out is SO much easier, and double that in winter gear.

MTV
 
Why EXPERIMENTAL? You would only qualify for Exhibition and still need to comply with all of Part 43 (Read 43.1), no real advantage there. I don't see any reason that couldn't be done either with a DER approval or a Field Approval.
 
Here's a photo showing the Javron modified door without fabric on. If you want photos from any other angles for reference let me know and I'll take some for you.
View attachment 68398

That's exactly what I wanted to see!!!! That's exactly what I'd end up with if I modified my frame. Thanks Dude!
For structural purposes each bay should form a triangle. There appears to be a tube missing starting at the cluster where the top forward door latch goes. That tube should go down to the lower engine mount cluster. My fuselage has a tube there.
 
For structural purposes each bay should form a triangle. There appears to be a tube missing starting at the cluster where the top forward door latch goes. That tube should go down to the lower engine mount cluster. My fuselage has a tube there.

The upward sloping tubes are added to decrease the likelihood of the lower engine mounts collapsing up and trapping your legs in a crash. With the modified door shape, I believe Javron routes that tube (highlighted red) to the lower door sill to allow the force to continue rearward (yellow arrows). The tube on the left hand side is routed as you describe (highlighted blue)

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The upward sloping tubes are added to decrease the likelihood of the lower engine mounts collapsing up and trapping your legs in a crash. With the modified door shape, I believe Javron routes that tube (highlighted red) to the lower door sill to allow the force to continue rearward (yellow arrows). The tube on the left hand side is routed as you describe (highlighted blue)

View attachment 68404
That's a better picture. The triangles are there.
 
IMG_4655.jpg
you have t look close, right side of the photo you can see a couple extra tubes. One from the lower engine mount to the door/windshield cluster. The other from the lower engine mount cluster to the bottom front corner of the door.

I had my airframe plan loaded into Solid Works and had an aeronautical engineer run a structural analysis on it. There were no issues with the modification as I did it.
 

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Having flown some Huskys with the larger door, I can tell you that this is a brilliant move. As we age, sliding in and out is SO much easier, and double that in winter gear.

MTV
My 85 year old Dad says getting in and out of his Clipper keeps him limber. ;)
 
Why EXPERIMENTAL? You would only qualify for Exhibition and still need to comply with all of Part 43 (Read 43.1), no real advantage there…
School me dgapilot. I’m probably coming from a point of ignorance, but I thought EXP Exhibition allowed you to do whatever you needed to do to perform the exhibition, which in reality left the door wide open. Back in the day, we’d bought old duster Stearmans in Restricted Category. We’d leave them in Restricted if we were going to banner tow, otherwise we’d put them in Exh Exhibition. A buddy of mine still has his in Exhibition to this day. These are Stearmans with highlight wings (Vern’s 4412’s), metal sides, BT wheels and so on. When it comes to the Cub, I thought in the name of exhibition, say STOL contests, I could modify it in ways I believed would enhance it’s competitiveness, in this case, a structural mod to the door area. Again, I’m coming from a point of ignorance, you know more about it than me, but am I mistaken on my interpretation of EXP Exhibition?


…I don't see any reason that couldn't be done either with a DER approval or a Field Approval.
Is there a Super Cub fan DER on this forum or one that you’d recommend?
 
School me dgapilot. I’m probably coming from a point of ignorance, but I thought EXP Exhibition allowed you to do whatever you needed to do to perform the exhibition, which in reality left the door wide open. Back in the day, we’d bought old duster Stearmans in Restricted Category. We’d leave them in Restricted if we were going to banner tow, otherwise we’d put them in Exh Exhibition. A buddy of mine still has his in Exhibition to this day. These are Stearmans with highlight wings (Vern’s 4412’s), metal sides, BT wheels and so on. When it comes to the Cub, I thought in the name of exhibition, say STOL contests, I could modify it in ways I believed would enhance it’s competitiveness, in this case, a structural mod to the door area. Again, I’m coming from a point of ignorance, you know more about it than me, but am I mistaken on my interpretation of EXP Exhibition?

Dave.. Actually a number of people operated banner tows without a proper Certificate of Airworthiness. As a Van Nuys FSDO Inspector said to me... each FSDO is an independently operated concession with its own rules. The correct procedure was to apply for a Special C of A in Restricted Category for the "purpose of Aerial Advertising." Some had multiple airworthiness certs. I had an Inspector on Long Island give me a Restricted Cert for a Standard category PA-18 just because we were towing banners - that was without even making an application. How could he just issue a Cert without having received an application for a Certificate of Airworthiness? He was way off base, but fixed in is ways, so we just went about our business. When a California Central Valley operator had a pi--ing match with an inspector about licensing his AgCat for banner towing it set off a national ban on using AgCats for Aerial Advertising, with the FAA in Washington DC stating the FSDO Inspectors did not have the authority, and could not issue Certs of airworthiness. Everyone lost out. What I read here and elsewhere is that taking a Standard airplane into Experimental is not a good idea at all - and that EX-Exhibition will likely drastically reduce the resale value of your airplane.

 
School me dgapilot. I’m probably coming from a point of ignorance, but I thought EXP Exhibition allowed you to do whatever you needed to do to perform the exhibition, which in reality left the door wide open. Back in the day, we’d bought old duster Stearmans in Restricted Category. We’d leave them in Restricted if we were going to banner tow, otherwise we’d put them in Exh Exhibition. A buddy of mine still has his in Exhibition to this day. These are Stearmans with highlight wings (Vern’s 4412’s), metal sides, BT wheels and so on. When it comes to the Cub, I thought in the name of exhibition, say STOL contests, I could modify it in ways I believed would enhance it’s competitiveness, in this case, a structural mod to the door area. Again, I’m coming from a point of ignorance, you know more about it than me, but am I mistaken on my interpretation of EXP Exhibition?



Is there a Super Cub fan DER on this forum or one that you’d recommend?
dgapilot is a DER.
 
School me dgapilot. I’m probably coming from a point of ignorance, but I thought EXP Exhibition allowed you to do whatever you needed to do to perform the exhibition, which in reality left the door wide open. Back in the day, we’d bought old duster Stearmans in Restricted Category. We’d leave them in Restricted if we were going to banner tow, otherwise we’d put them in Exh Exhibition. A buddy of mine still has his in Exhibition to this day. These are Stearmans with highlight wings (Vern’s 4412’s), metal sides, BT wheels and so on. When it comes to the Cub, I thought in the name of exhibition, say STOL contests, I could modify it in ways I believed would enhance it’s competitiveness, in this case, a structural mod to the door area. Again, I’m coming from a point of ignorance, you know more about it than me, but am I mistaken on my interpretation of EXP Exhibition?

Dave.. Actually a number of people operated banner tows without a proper Certificate of Airworthiness. As a Van Nuys FSDO Inspector said to me... each FSDO is an independently operated concession with its own rules. The correct procedure was to apply for a Special C of A in Restricted Category for the "purpose of Aerial Advertising." Some had multiple airworthiness certs. I had an Inspector on Long Island give me a Restricted Cert for a Standard category PA-18 just because we were towing banners - that was without even making an application. How could he just issue a Cert without having received an application for a Certificate of Airworthiness? He was way off base, but fixed in is ways, so we just went about our business. When a California Central Valley operator had a pi--ing match with an inspector about licensing his AgCat for banner towing it set off a national ban on using AgCats for Aerial Advertising, with the FAA in Washington DC stating the FSDO Inspectors did not have the authority, and could not issue Certs of airworthiness. Everyone lost out. What I read here and elsewhere is that taking a Standard airplane into Experimental is not a good idea at all - and that EX-Exhibition will likely drastically reduce the resale value of your airplane.


“It depends”, I operated banner tow airplanes for about 10 years. So long as there is a legal way to install a hitch and stay standard there is no reason to put an airplane in “Restricted”. If there is a reason you can’t stay standard, a boom hitch, extended fuel system or no cowling are examples, then you go Restricted.

43.1 (b) in part says “This part does not apply to -
(1) Any aircraft for which the FAA has issued an experimental certificate, unless the FAA has previously issued a different kind of airworthiness certificate for that aircraft;”

Given the plain language of the regulation, 43 still applies. One of the reasons for requiring an annual program letter is to inform the FSDO what you are doing with the airplane. It is also the reason why there is an operating limitation that says any change that meets the definition of 21.93 must be coordinated with the FSDO. I’ve issued a number of Field Approvals and 8110-3s that explicitly state they can only be installed while the aircraft is operated in Experimental Exhibition (or Restricted). A big reason is to document changes while Experimental in case the owner chooses to return the aircraft to Standard. Makes the conformity for returning it much easier.


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A bit of thread drift, however, since it is addressed, I shall add my opinion...I Agree with DGA (post #9).
Start from the beginning when entertaining thoughts of changing Category. Review 91.313 (Restricted) and 91.319 (Experimental). One of the most prolific examples of Category "abuse" as previously mentioned is the A75 series Boeing "Stearman". Plentiful in Restricted Category for Agriculture and Pest Control back in the day, what to do when one replaces the hopper with the original front pit. Legal to fly in Restricted? Depends. If used under 91.313 (b) it may be. I say "may" because at the end of the day it is the governing agency (FAA) that holds the final say. After conversion back to 2-hole configuration, I continued to operate my Restricted Category Stearman for years in that Category. No issue as I was working with a Part 137 operator, and we used the Stearman for said training under 91.313 (b). Once I was no longer working with that Ag operator, I hired a DAR to slide over to Experimental (that's another story). There are positives and negatives of operating in the Experimental Category that are beyond the scope of this thread. Both Restricted and Experimental have subcategories specific to the purpose for which the certificate was issued. One cannot switch between "purposes" without authorization. Exhaust all regulatory facts, consult with subject matter experts and make an educated decision. TR
 
A bit of thread drift, however, since it is addressed, I shall add my opinion...I Agree with DGA (post #9).
Start from the beginning when entertaining thoughts of changing Category. Review 91.313 (Restricted) and 91.319 (Experimental). One of the most prolific examples of Category "abuse" as previously mentioned is the A75 series Boeing "Stearman". Plentiful in Restricted Category for Agriculture and Pest Control back in the day, what to do when one replaces the hopper with the original front pit. Legal to fly in Restricted? Depends. If used under 91.313 (b) it may be. I say "may" because at the end of the day it is the governing agency (FAA) that holds the final say. After conversion back to 2-hole configuration, I continued to operate my Restricted Category Stearman for years in that Category. No issue as I was working with a Part 137 operator, and we used the Stearman for said training under 91.313 (b). Once I was no longer working with that Ag operator, I hired a DAR to slide over to Experimental (that's another story). There are positives and negatives of operating in the Experimental Category that are beyond the scope of this thread. Both Restricted and Experimental have subcategories specific to the purpose for which the certificate was issued. One cannot switch between "purposes" without authorization. Exhaust all regulatory facts, consult with subject matter experts and make an educated decision. TR

If you put the front cockpit back in what kept you from going back to Standard? Wings? Engine? I’ve seen a number of airplanes that really should have gone back to Standard but for some reason they went Experimental Exhibition.


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dgapilot, As previously stated, "that's another story" which is neither applicable nor appropriate for this thread. Feel free to PM me if you desire to know the logic and reasoning for the transition to Experimental for this particular former duster/sprayer A75 series Stearman. I cannot speculate the reasons for the airplanes you feel "really should have gone back to Standard", however, I can share why my particular example is not, as well as many other former dusters and sprayers of this make and model. TR
 
I have scanned the baggage door threads, and still have a question. Can a door be added to a certified PA-18 without an STC if no structural tubing is changed? How about something like the photo attached? Leaving the diagonal tube in place. baggage door.jpg
 
School me dgapilot. I’m probably coming from a point of ignorance, but I thought EXP Exhibition allowed you to do whatever you needed to do to perform the exhibition, which in reality left the door wide open. Back in the day, we’d bought old duster Stearmans in Restricted Category. We’d leave them in Restricted if we were going to banner tow, otherwise we’d put them in Exh Exhibition. A buddy of mine still has his in Exhibition to this day. These are Stearmans with highlight wings (Vern’s 4412’s), metal sides, BT wheels and so on. When it comes to the Cub, I thought in the name of exhibition, say STOL contests, I could modify it in ways I believed would enhance it’s competitiveness, in this case, a structural mod to the door area. Again, I’m coming from a point of ignorance, you know more about it than me, but am I mistaken on my interpretation of EXP Exhibition?



Is there a Super Cub fan DER on this forum or one that you’d recommend?
Most people ignore the 43.1 and 91.319 requirements but they are there. As for a SuperCub friendly DAR or DER, you are talking to someone with both.
 
I have scanned the baggage door threads, and still have a question. Can a door be added to a certified PA-18 without an STC if no structural tubing is changed? How about something like the photo attached? Leaving the diagonal tube in place. View attachment 105260
I know that the Performance Air Motive STC only covers the structural tubing modification and the door is up to the installer. The door itself doesn't seem to be major to me. I can tell you I love this STC with the big opening. Makes loading way easier.
 
At Johnson Creek one year, the late Jim Richmond took my high powered full sized folding ebike I carry in my RANS S-7S (when solo, but with full camping gear also) routinely for a ride. He liked it enough to wonder how it would fit in the back of the X Cub (I think it was, the fast, spring steel geared model). Turns out it didn't/wouldn't. Door too small, pilot seatback didn't fold forward, no way was it going to fit. That of course gave me a renewed appreciation for the dual 5' long door I have, and also squashed any plans I had to blow 350K on a X Cub. Ha ha.
 
At Johnson Creek one year, the late Jim Richmond took my high powered full sized folding ebike I carry in my RANS S-7S (when solo, but with full camping gear also) routinely for a ride. He liked it enough to wonder how it would fit in the back of the X Cub (I think it was, the fast, spring steel geared model). Turns out it didn't/wouldn't. Door too small, pilot seatback didn't fold forward, no way was it going to fit. That of course gave me a renewed appreciation for the dual 5' long door I have, and also squashed any plans I had to blow 350K on a X Cub. Ha ha.

A full sized road bike fits in the back of the Sport Cub/Carbon Cub with the aft seat stowed, along with camping gear even in the standard baggage area. The only disassembly required is to take the wheels off. This bike is a 56 size frame for a 5'10" rider. I've not had opportunity to try it in an XCub, but they have the same size door opening and roughly the same back seat area so pretty sure it should work. My larger framed gravel and mountain bikes probably would not fit but I have done it with a couple different road bikes.
 

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With the Montague, you take the front wheel off (quick and easy) but you don't have to take the rear wheel off, which is a bit of a pain and involves messing with the chain of course. It looked like plenty of room for it, as i recall, if the pilot seatback folded forward would have helped a lot. Good to hear you have your setup figured out, bikes and planes are a great combo.
 
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