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Well, its started, the experiment

C

chugach3dcomp

Registered User
anchorage, ak
Hello supercub.org

This is my first experimental build, was saving for a new fuselage when, well a used one came available. I thought well lets do this, I like a good challenge. So I got the fuselage, It appeared to be in good shape, with no major issues. After a quick inspection, off it went to get sand blasted. A few things showed up that I was already prepared for, D channels rusted and right side lower longeron has what looks like small pitting.

Now the real question, is it straight? I was super lucky in the fact that I was able to borrow a jig and my buddy has space at his house for me to work on it. So I headed out to pick the jig up and on the way back through with the help of a friend placed the fuselage in the jig. To my surprise stuff started to line up. Motor mount holes in, lower gear fittings in, left side wing fittings in, then well I would like to say the right side wing fittings lined up but they didn't, off by 3/16, crap. Then we checked the tail, a little high and long(appears the tail has been replaced before) but it has this slight turn to the right. Overall not bad.

Goal now is to make this fuselage fit, convert over to L21 since the D channels need removed, replace lower longerons from front to rear and add the necessary mods(its just time right lol).

I do have to say I appreciate this sight as there is a load of info(long time looker before I joined up).

Overall I think I will enjoy this process more as I will get a better understanding as to what goes into fixing a fuselage.
 

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Looks fun. Measure the jig before you get too carried away. Never hurts to check.

Is that a Piper fuselage or originally an experimental?


Sent from my iPhone using SuperCub.Org
 
I have a question that I’m hoping someone may be able to help with. The lower longerons appear to have a upward bow in them. When putting a straight edge on the bottom you can tell. The previous owner had the tail replaced and I’m wondering how or what to cut to make everything straight again. B9B8B3BB-DE3F-4C2A-ABF4-B7135C830905.jpg16ECA00A-5DFC-4DA4-AA62-B4CE634CF698.jpg
 

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Pretty common for the tail to bow upwards over time. Since you're replacing lower longerons I would start with cutting out the sections you plan on replacing and seeing if the tail can be persuaded to sit in the jig right. The longerons are primarily responsible for that bow.
 
Be careful with angles and dangles when you are replacing tubing. Before you do more then tack the tubing where you want it stick the jackscrew and stabilizer in. Level the fuselage and jig. Then measure you tail angles. Check against firewall and wing angles. That upper longerons looks like it is sway back also to me but could just be the picture. DENNY
 
Denny's right, check everything before cutting. The upper longeron is definitely bent right at where the stabilizer support bracket is. Take all the stringers and vertical fin off and start by figuring out where the longerons are no longer straight and going from there. Make sure you have drawings on hand and know where the tubes are supposed to be pointed. You can have a fuselage that fits in a jig but is still all crooked in between the gear fittings and tail post.
 
Crash said:
Denny's right, check everything before cutting. The upper longeron is definitely bent right at where the stabilizer support bracket is. Take all the stringers and vertical fin off and start by figuring out where the longerons are no longer straight and going from there. Make sure you have drawings on hand and know where the tubes are supposed to be pointed. You can have a fuselage that fits in a jig but is still all crooked in between the gear fittings and tail post.
Click to expand...

Thanks,

Yes i have the drawings and did some quick measurements last night, the things i measured actually measured right but will continue to mess with it.

Thanks agian,
joe
 
The longerons are being held in place by the diagonals. The diagonals at the bottom of the tail post should terminate at the bottom longerons not at the tail post like yours are. The top longerons have a very distinct bow ahead of the rear stabilizer fitting. I would start working forward and see what lies ahead of there. Easiest solution might be to use a fuselage tail repair section, cut the old off and sice the new one in.
 
Depending on what’s planned for wing mods? Now would be the time to extend the length and/or make provisions for electric trim.
 
4D97D4B1-096E-46D4-B906-592C275619EF.jpgEE520EA5-86A2-4808-A562-51846F9032F3.jpg
Steve Pierce said:
The longerons are being held in place by the diagonals. The diagonals at the bottom of the tail post should terminate at the bottom longerons not at the tail post like yours are. The top longerons have a very distinct bow ahead of the rear stabilizer fitting. I would start working forward and see what lies ahead of there. Easiest solution might be to use a fuselage tail repair section, cut the old off and sice the new one in.
Click to expand...

Good morning Steve, thanks for the reply. I am unsure as to what your describing. I took a picture for reference of a known good fuselage and checked the diagonals agianst that. It seems as if there in the same location?? I left my schematics at the house last night so i was unable to get exact measurements.

thanks again,
 

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chugach3dcomp said:
View attachment 56875View attachment 56876

Good morning Steve, thanks for the reply. I am unsure as to what your describing. I took a picture for reference of a known good fuselage and checked the diagonals agianst that. It seems as if there in the same location?? I left my schematics at the house last night so i was unable to get exact measurements.

thanks again,
Click to expand...

In the drawing, the diagonal touches the lower longeron and is welded to it.

Your diagonal looks like it is approximately an inch higher. So it will tend to twist the tailpost forward, bend the lower longeron downward, if the tail wheel hits hard.

tailpost.jpg

I remember some discussion about this with some of the after market fuselages.
 

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thanks for all the replies!!! due to the condition of the lower/upper longerons just decided it would be quicker to order a complete tail section from airframes. Airframes said i should have it in about 6weeks, so hopefully ill have some more updates on this project.
 
Excelent plan. I have seen what it takes to splice repair longhorns that had linseed oil in them and it is a major pain in the butt. DENNY
 
Well I finally received the tail section so it was out with the old and in with the new.

now that that’s completed, it’s on to the lower baggage. My question is, can I just make my own large baggage door style or does the tubing have to be placed in a certian area? (this is an experimental build)DF685E70-A5A6-418F-9BDE-DB4BC17EB509.jpg
 

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Last edited:
Make you own as big as the tube compartments allow. My door is top hinged and I wish it was hinged on the forward vertical edge instead so it'd blow closed in flight. A neighbor waved me off a takeoff last summer because the door was open. That wouldn't have ended well.
 
chugach3dcomp said:
Well I finally received the tail section so it was out with the old and in with the new.

now that that’s completed, it’s on to the lower baggage. My question is, can I just make my own large baggage door style or does the tubing have to be placed in a certian area? (this is an experimental build)View attachment 57866
Click to expand...

I would buy the airframes extra large baggage door system.. It dog-legs one tube to make the door even larger than what you can do with the standard tubing.. Its $295 so its worth it in my mind to give them the business even though it is experimental.

Brian.
 
My Baggage door is hinged at the top. It is hard to seal up from rain. Also it looks closed even when not secure. Put the hinge on the bottom. Easy to seal from rain on the top and it will hang open so easy to spot when you get in. As far as door size Airframes has a lip, drop that bottom tube down so you have no lip when sliding heavy stuff in and out. DENNY
 
DENNY said:
My Baggage door is hinged at the top. It is hard to seal up from rain. Also it looks closed even when not secure. Put the hinge on the bottom. Easy to seal from rain on the top and it will hang open so easy to spot when you get in. As far as door size Airframes has a lip, drop that bottom tube down so you have no lip when sliding heavy stuff in and out. DENNY
Click to expand...


thanks Denny, never gave any thought about the lip, thats good info to know
 
Someone at Atlee's told me Butch Cavanaugh who owns the STC originally intended it without the lip but thats not how Airframes/others have been installing it. Randy at Carbon concepts told me he has at least 3 different patterns for these doors based on the height of the lip. The layout of the tubes is open to interpretation a little bit.
 
WayneK49 said:
Someone at Atlee's told me Butch Cavanaugh who owns the STC originally intended it without the lip but thats not how Airframes/others have been installing it. Randy at Carbon concepts told me he has at least 3 different patterns for these doors based on the height of the lip. The layout of the tubes is open to interpretation a little bit.
Click to expand...


I think Im questioning the placement of the tubes because if i put them in the wrong location, would it cause a structural concern. Seems as though it should not
 
Would anyone here know if there is a tool for bending the u channel for the gingerbread and overhead turtle deck?
 
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