tenacious101010

My Feedback: (97)

I recently purchased this 94 inch wingspan F7F Tigercat. It appears it was just for display purposes. It has some retracts installed that appear to be designed for RC flying but they were never mounted solid enough, will barely support the weight of the plane sitting on them without collapsing the mounts. The nose section from the bulkhead behing the nose gear forwarsd was so weakly attached, it has broken loose and I have begun securing it back in place. It will Take some carbon fiber and epoxy to make it structurally sound. The center wong section is the most questionable and will be the toughest to make as strong as it needs to be. I will have to use an insoection mirror to further inspect inside the wing to see if it can be strengthened as would be required. Again, some ply, balsa, epoxy and carbon fiber will be required to make it airworthy. The outer wing panels are made to use round tubes to hold them and align them, the fit is not great and I think I will redo them using carbon fiber or new aluminum tube for structure. There is already pull-pull connections at the elevator and rudder so if they are secure, that should be easy to get right. The props and spinners are not airworthy items. There was a really nicely made alumin tube and base mount attached to the engine firewall to insert another aluminum tube into to attach the 3 blade props, the fiberglass spinners and delron back plates for the spinners. The hinges for the flaps, gear doors are not strong enough in my opinion. Actually, the hinges are machined aluminum, but the attackment is not strone enough. This project is different than any I have taken on before. I have built several kits, done some giant scale scratch building but this is so different. This plane is so complete, I will have to try to build from the inside out. The Giant RC airplane equivelant of building a ship in a bottle. Luckily, the ribs have nice big lightening holes that I can use to inspect the internals. I have some small aircraft inspection mirrors and even some endoscopic inspection and tools used for operating on people that will be helpful to evaluate the strength of the structure. This is a big plane, with two 160 Outrunners on it, it will not only be big but fast, safety will be first by far. I would rather burn it than take a chance on anyone or anything being hurt because of a structural failure. So now, the next step is a thorough inspection and evaluation of the structural integrity of whats already here, next if I deem it practical to solve any structural issues, I will begin formulating a plan to upgrade the airframe before worring about servos, motors, retract actuation and such. I thought I would do a build thread on this unusual project. I know not many would take on such a project and many feel its not worth it. Oh well, I am gonna give it a try! This will be my first twin.
Denny

tenacious101010

My Feedback: (97)

This was built with many access panels, not what I would expect from a static display model build. I get the feeling I will be in for more surprises, and not all good ones. I depaneled the plane. The bottom of the fuselage has a huge long removable section that extends from just behind the nose gear to behind the trailing edge of the wing. Also on top, both engine nacelles have good sized access panels on top that can be removed, they are just above the wing. These removable panels have allowed me to study the interior of the wing. The guy that built this must have had a motto that went something like" who needs stinking wing spars!". They have been cut away in a couple places and look like they were never there in a couple other places. Its going to take some creativity to remedy this. I will deskin the bottom of the wing if I have to. Right now, I am thinking I can get the spar and web in there with the access I have. I will suppliment this with carbon fiber rods running the length of the wings. I have some nice long drill bits that should work great for making holes in line for some of the smaller CF rods. This is gonna be tough. With my tendency to overbuild things, it will get a bit heavier. In the picture of the bottom of the wing center section inside the fuselage, you can see that first, the sheeting on the lower wing doesnt even extend to the center ribs. Also, the stringers are missing between the center ribs and the next ribs. The center ribs are bolted together in two places, and no sign of glue! Thank god for carbon fiber, I will need lots after I get the wood installed. Looking in the top of the access panel in the nacelles, there are no stringers, webbing, spars or sheeting at the opening, it was all cut away or was never there in some cases. The center wing section has an aluminum tube at one wing for the outboard wing panels tube to insert into. Well, the wing tube in the center section does not even make it to the second rib in. All the issues I see so far, I can deal with, abeit some time, but I can do it. This plane is just too nice not to try to save it.

tenacious101010

My Feedback: (97)

After considering different options as to where to start this project I decided that no matter what else I did or whether or not I even ever got it flying, it wont even make a good static display if it cant sit on its own gear without collapsing. So I started on the worst, the nose gear. I installed a couple cross members that will at least give me a stable and repeatable mount to locate the nose retract. Now that I have a repeatable location I can start to build sone structure to hold the nose section to the rest of the fuselage structure. Next I will tie the retract mount to that structure. I will have to add some stringers that had been removed along with some bulkheads. I cut some openings in the aft bulkhead in the nose and inserted some hardwood to extend the fuselage framework further forward. I should be able to tie into this to strengthen the nose.

Brad330l

My Feedback: (1)

Well you've done it now!!!!! (started)
I love this airplane so have voted for success.

Good luck, I'll be watching.

Brad

tenacious101010

My Feedback: (97)

LOL, Thanks for the vote of confidence, now the pressure is really on to succeed. Last evening, I made part of the motor mounts, I still need to make 8 standoffs 1 1/4 inches long. I used some 4 inch aluminum square tubing for the majority of the mount. The conversion to electric power requires a total of 5 1/4 inches motor mount/spacing to the firewall to get the props where they need to be. I need to learn about the proper angle to mount the motors. A bit of research is due. I thought I read somewhere about tilting the motors inboard X number of degrees. I cant remember where I read it.
Denny

tenacious101010

My Feedback: (97)

Well, I have the Tigercat where it can at least sit on its own gear without collapsing the attachments. It is substantially beefed up. Still more work to be done in the nose but its far better than it was. I have the motors mounted. I mounted them straight ahead, no outward or downward angles. Now that I know the nose section can be made structurally sound, I suppose I should get to work on the wing. That is the area that is most critical for it to be made airworthy. If I suceed with the center wing section, the rest will be much easier to do. I stuck the panels on and put the plane together for show. We are having a big bird meet at TRAC this Saturday and I want to bring it out and show some of the guys at the field. This may be the biggest electric powered airplane any of them has ever seen. Actually, it is the biggest I have ever seen in person.
Denny

91zulu

My Feedback: (2)

The wing don`t look too bad. The drilling of holes and then fitting carbon rods is the route I would take. For the center section I would insert a 1/2 inch rod at the trailing edge and a 3/4 at the leading edge. For the outer panels 1" for the plug in up to about 1/3 or 1/2 way and maybe another 1/2" along the trailing edge. That`s not going to brake in flight.
Looking good though.

tenacious101010

My Feedback: (97)

I finished several other projects and today began a thorough study of what it will take to make this fly and how to go about that. I decided that I need the wing to be strong, the most important first goal. If I cant make the center wing section strong, there is no use attaching anything to it. Upon close inspection I see that there is a forward main spar and a rearward one. The forward one at approx. the Center of gravity needs to be the strongest. I see that there is no center span plate attaching the left wing half to the right wing half. This "Crutch is not optional. There is not one at the rear spar location either. There is a center plate vertical running from front to rear of the wing made from 1/8 thick pressboard like you find at home depot, similar to what pegboard is usually made from. The innermost wing ribs are held to this with three 1/4-20 bolts. Its very weak, I am having a "What the heck have I gotten myself into" moment. The balsa sheeting on the top of the wing ends about two inches from the ceter wing joint too. To put this sheeting in, the wing has to be removed from the fuselage, or the fuselage cut away so the sheeting can be installed. I also noted that the wing spars are cut off in the area where the retracts are to give clearance to the wheels and retract mechanisms, gonna take some creative wood working to make that part strong.
I decided to cut the wing away from the fuselage, I didnt want to, but I see now I wil have to. The wing is not glued well at the wing skin joint with the fuselage so I began cutting that joint parallel with the wing sheeting. I removed some of the interior fuselage structure running from front to rear to get better access to the wing. In the picture you can see, I have used a hacksaw blade and have begun cutting the fiselage along the wing. I hope to detach the wing at this point, unbolt the center wing section, pulling each wing half out. I can then access the wing structure and get it as strong as it needs to be. I will end up having to attach the two wing halves while they are inserted into the fuselage, that should be fun.
I think completion of this part is the hardest and most critical part of getting this thing structurally sound.... What have I gotten myself into....

tenacious101010

My Feedback: (97)

Well, I went for it, the wings came right apart. I sawed around the edges where the wings met the fuselage, removed the bolts and the wing halves came out, they were just tacked in lightly. As I was removing the wings a crack across the top of the fuselage formed going along one side to the other, that actually worked out perfect. I will remove the top section of the fuselage above the wing. I can then build the wing complete then drop it into the fuselage and replace the portion of the fuselage I had removed. At least now the model is in smaller parts and will be easier to fit onto my workbench.

tenacious101010

My Feedback: (97)

I wonder, at what point in this project I might stop saying, "What have I gotten myself into?

tenacious101010

My Feedback: (97)

I have the center wing joiner fabricated and fit to the left and right wing. I made it from two layers of 1/8 in aircraft grade ply. It spans 3 ribs into the wing. Where the joiner ends, I will continue with 1/8 ply web for the front wing spar. There is a rear spar with hardwood on top and bottom about 2/3 back from the leading edge of teh wing. I am going to make a 1/8 inch thick wing joiner for that spar and do the webbing from 1/16 ply. That should give me a fairly strong wing with minimal weight penalty. If the wing spar hardwood was standing vertical like most builds, I wouldnt but so much robust webbing in place. If I add a nice sice carbon fiber tube also, I will have the structure to support the outer wing panel attachment with no structural concerns. I have to keep reminding myself, this is electric, not gas or glow, I wont have the vibration trying to shake apart the airplane. I remember a someone here said,"If you dont have a structural failure now and then, you are building too heavy. I dont want to have a structural failure, but I want to build close to having one, but not quite. Its like walking on the very edge of a cliff, dont dare make one bad step or its all over.
Denny

tenacious101010

My Feedback: (97)

I may have overbuilt the main wing spar by using the 1/8 inch thick ply for webbing on the center wing section but I decided against using a large carbon fiber tube to strengthen the wing. Instead, with the 1/8 ply webbing on the main spar and using 1/16 ply on the second spar, I should have plenty of strength. I am now looking at attaching the outer wing panels to the center section using wing joiners from "GIANTSCALE TWINS". I used these on my big BT-13 and they worked great and are a whole lot easier to install on a wing already built. The 1/8 webbing is done on the main spar. Took some unique tools to do it, but its done. I am sure building a ship in a bottle takes special tools also, lots of long skinny ones. I suppose its time to start on the webbing for the rear spar. After that, I suppose a good inspection of the engine and main gear structure to wing will be the next step I should do. I will wait as long as possible to join the two wing halves, much easier to work with when smaller.
Denny

tenacious101010

My Feedback: (97)

I stepped away from this project for a bit to reflect on the wing structure and the attachment of the outer wing panels. I decided to go with aluminum tubes because, they are lighter than the wing joiners and will be stronger and spread the stress of the outer wing panels over a larger area, much preferred. I have one of the aluminum wing tubes inserted in the left wing, now to get the holes into the outer wing panel. Now that I have the toughest part of this project behind me, its just a matter of spending the time to complete it.
Denny

tenacious101010

My Feedback: (97)

I started a new job and havent been able to work on the Tigercat. I put it up for sale but if I dont get the price I am asking, I will gladly keep it and get back to working on it soon. I have some updated pictures I took a few days ago. I suddenly cant post pictures to RCU here or in marketplace. If interested, email me and I will send pictures.
Thanks, Denny

tenacious101010

My Feedback: (97)

The last picture is for a gentleman who called from Louisiana asking fr the width of the Main gear mounting. I wanst able to return the call with the width, so here it is.
Denny

tenacious101010

My Feedback: (97)

Well, I have the BT-13 done so I am going to get back to work on the Tigercat. I am going to start on the outer wing panel attachment to the center wing section using aluminum wing tubes. I have the parts on the bench and will get pictures as I go.

Desertlakesflying

My Feedback: (28)

Why would you want to?

tenacious101010

My Feedback: (97)

good question...