? ? ?I have a newfound respect for what everyone says when they say they are "90% finished but 90% left to do"!!!! I feel like I should have been finished with my build last spring!! I can safely say that my completion is finally around the corner, I hopefully will have my plane ready to move to airport by end of winter. Anyways, as I wrap up my fabric install, I would like to get everyone's insight on access panel/doors! I got to thinking! Everyone has been installing the clear plexiglass inspection door in the vertical stabilizer using fabric glue to adhere this to the inner fabric. This made me wonder if anyone has used this method to create an actual inspection door that can be removed and reinstalled? My question, do you all think it would be effective to create an access door by first gluing a square window cut out of plexi on the inner fabric, cut the fabric at this opening and wrapping/gluing the cut ends of the fabric to the inner most aspect of this plexiglass window. After doing this, then cut another square that is slightly smaller, gluing this on the inner most aspect of the first square already installed, creating a lip, which would act as a supportive backing and allow a square door of the plexiglass to simply be screwed into this new opening during inspection and or assembly of the plane? Is anyone using this method already or is this how its currently done on the W10 for access to the elevator horn??

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? ? ?A brief background on my build! I basically have a cougar airframe; however, I have literally rebuilt 85% of the structure to match as close to the W10 blueprints that I could with the blessed help of everyone on this board. Wanting to maintain the plane's original control geometry and because of time's sake, I have preserved some of the cougar components. While I have rebuilt the vertical and horizontal stabilizer/elevator, at least at this time, I decided to keep the aluminum jack screw trim set up, since the one on the airframe appears to be fairly light, new, and in working order. Keeping these properties creates additional considerations during assembly that the W10 has simplified. I have the need for access to bolt the leading edge of horizontal stabilizer to the jackscrew trim, the need to access and bolt the two horizontal stabilizer struts together on the inner fuselage, as well as the need to have access to the elevator control arm/horns where they come together at the inner side of the fuselage. Currently, my plan is to use the lower rear fuselage area to install one large plexiglass access panel which should allow enough room to access and install the leading-edge stabilizer to jackscrew trim, as well as enough room to assemble/attach the two struts of the horizontal stabilizer. What I am having issues with, I don't believe I have enough room through the bottom to reach and secure the elevator control arms together. I thought maybe I could go down through one side of the vertical stabilizer similar to the W10 design, however the cougar elevator control arms are pointed downward instead of upward like on the W10. Since the fabric in the area of elevator insertion through the fuselage will require openings already, my thought would be to use the suggested method noted above and create removable access on at least one side of the fuselage in this area to assemble the elevator control arm halves. I would have to make a "door" that is made of two halves of plexiglass, that way it can be reinstalled around the elevator where it goes through the fabric and be fully sealed off and aerodynamically clean. I cannot think of a better method for accomplishing this task and do not like the "eye-sore" of having bulky sheet metal skin on the exterior fuselage like that on a cub, creating turbulent airflow. Since the Cougar trim requires movement at the leading edge of the horizontal stabilizer, similar to the cub, my plan is to glue plexiglass on the inner fabric in this area and simply cut the needed path for this movement through the plexiglass/fabric. Do you believe this method would work?

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? ? ?I know there are many on this board who have this similar "cougar-ish" set up as mine, and I would be grateful for any input you all have that would help me tackle this roadblock so I can move closer to the finish line. Also, I am open to constructive criticism or input from anyone regardless of if you have a similar set up or not. You all have been so valuable and instrumental towards getting me this far in my build. I can't thank you all enough! Sorry for the lengthy post!!! I am hoping this will be one of the last obstacles I face in my build.??

There was nothing scientific about how I tested the glue. 3M does publish some strength info but I'm just one step above a caveman so I was more interested in more of a common sense result. I would consider this a peel test and the 2216 required me to take a pair of needle nose pliers and essentially wrap the metal around the pliers to get it off. In technical terms, that crap was stuck pretty good. Good enough for me. Both glues I tried with any of the prep methods worked much better than I expected and I think are more than adequate for the job particularly when you consider the use of blind rivets will add to the integrity.

Excellent data, thanks for sharing it!

I intend to construct my doors with 3/4" square 6061-T6 covered with 0.020" 2024-T3. I wonder if this would yield similar results?

In the event that anyone was curious about a couple of the glue options for bonding the aluminum skin to the door frames, I made up a little sample to test the 3M 2216 vs the 3M 38315 panel bonding glue. The sample was a piece of 5/8" square 4130 tube and .032 6061-T6 glued together a couple ways. The 4130 tube was bead blasted first then half was primed with Randolph Epibond, the other half was then lightly sanded with a flapper disc. The aluminum was degreased and scuffed with scotchbrite and acid etch, then alodined. I then primed a couple of those aluminum coupons and left a couple bare. While all the bonds were pretty good, the strongest was 2216 on bare steel and aluminum, the 2216 on both primed steel and aluminum was next best and almost as good as the first sample. The 38315 on bare metal was next on the list and the 38315 on primed surfaces was by far the easiest to separate. All bent the metal when I tried to peel the aluminum off, but there was a significant difference in the effort required to tear it apart between the worst and best FWIW.

The plans call for a step down in tube diameter outboard of the connector tube to match the tip dimension. ?This is a welded splice at this transition. ?Why not just flatten the tube to transition to the smaller profile? ?Seems like this would be easier to fabricate and be lighter/stronger.

And another lot of Spruce

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My prior project in another lifetime was a Spencer Aircar.? Unfortunately the folks who bought the design rights from Spencer did not keep things going very well.? All the assets are currently up for auction.? While there is a bunch of junk, there are some interesting items.? One specifically that someone who is within driving distance should scoop up on it there is a lot of Aircraft Grade lumber.? Most of the best spruce was cut down long ago, This stuff has been sitting around for probably 40 years, there is spar stock 18 feet log.? I would be surprised if there was not some very usable wood in this lot.? Current bid is $1.00

Auction Site:

Aircraft Grade Lumber lot:

Best of Luck,

Doug

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John Haedtler

Thank you Robert. ?Zero/Zero on thrust and 10 inches. ?Easy!

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What drove you to add the inch on the engine mount - CG, access, or something else?

Ok, let me try ask this another way…

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Given a conical mount Lyc 4 banger, what is the current, accepted distance from the firewall to the front of the engine mount spools (the engine to mount interface point)?

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What is the current, accepted thrust angle for a 130HP engine (side and down)?

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My thanks.

Appreciate the insight, guys. ?Has the engine location evolved over the years or is the XYZ and thrust angle stable?

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reason I ask is because the Starduster design has had some fairly radical changes over the years, and even things like the thrust angle on rag wing Pipers is open to modification.

Here are a couple of pics. If there are any other area’s you need pics of let me know and I will see if I have any of them.

Jim is correct, 68X is conical and I will see if I have some pics of it when we had the engine off.

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Dom

Copy. ?I have enough info for a material order now. ?My thanks

Can you describe the changes Jim? ?