tfarmer96

I have been ask to start a thread for the TF spit. So here it is with the links to all my questions. This is my first build and i think its a great kit. I have had a few stupid questions but you guys have helped me fix all the bumps i have ran into.


http://www.rcuniverse.com/forum/m_38...tm.htm#3813717
http://www.rcuniverse.com/forum/m_38...tm.htm#3854829
http://www.rcuniverse.com/forum/m_39...tm.htm#3907715

http://www.rcuniverse.com/forum/m_38...tm.htm#3874921

saramos

It's great to see you doing a thread. Sharing information helps so many, including the ones doing the sharing.

Look forward to seeing your progress!

Scott

w3po

Hello Tfarmer I am onboard on this one
So far the progress here are:
I am finished with the tailfeathers, I have framed the top fuse and trimmed the sheeting.
By the way I found it practical to secute the bottom of the sheeting to the fuse ridge with large masking tape instead of the pins.
By the way when they mean put alcohol on the balsa to bend it they mean it. Last night I was fitting the top left side fuse and thought "I bend this a wee bit more it will be OK" SNAP!!!!
Got a bottle of alcohol (Alas the non drinking type)
Cheers from Maryalnd
Patrick

Bobman

My Feedback: (5)

If you all don't mind, I'm going to hop on this one also. Just dug my multi-year old kit out of the pile & wiped off the dust. I won't get started until this weekend most likely as I need to setup my temporary shop in the basement first. Didn't get the new workshop completed before the cold weather hit here in the northeast (the Mrs. projects come first you know!) and it's NO FUN working out there with a small kerosene heater.

Bob

w3po

Tfarmer
I thought I saw somewhere on one of the threads that you went with the mechanical retracts from 3dx hobbies. If so what is the scoop as I was thinking to go the same route.
Cheers from Maryland
Patrick

tfarmer96

I must have gotten lucky. I got all hyped up about covering the wing i didnt use any thing to help it bend. I used masking tape and yellow wood ¨(tight bond II) to glue the skins down. I did get a pair of those retracts, but i went with the robarts at the end of the day. I looked at it and figured it would be a lot of trouble to put the mechanicals in. I am going to put them in my pts p51.

w3po

way to go on the wing skin, rubber bands, masking tape and clothe pins are the only things I have been using .
I have started to lay the ribs on the main spar, and I stopped at 5 as I am at the point to have to make a decision on the retracts.
Now with the mechanical retract can I use bellcranks to keep the servo amidship and be able to pull in and out with the retract body being at an angle?
As for Titebond I have gone so far without using anything else.
cheers from Maryland
Patrick

tfarmer96

You could push on. You know you are putting retracts in. you just cant put the skins on. I know i will get booed and hissed at for this but forget the flaps and you could put the retract servo in the spot where the flap servo goes. I thought about it but for 150.00 i just went with the robarts. You gotta check out this guys spit (saramos) He has his on off switch hidden and im thinking about stealing that get up.

w3po

Ok I will forge on anyhow. The retracts I am looking at are the same size as the Robart, and who know I might go crazy my LHS has the complete Robart system with lines valves etc for 120. I have to go down there tomorrow; I might go suddenly crazy. Bob I know how you feel I work out of the basement and it starts to feel a bit nippy down there.
Cheers from Maryland
Patrick

saramos

I've been working on the radiators today, and tested my HPLV gun for the first time. Perhaps Monday I'll do the hatch cover behind the cockpit and post some photos. The trickiest part of making the accessory box at the scale hatch location was getting it to fit the curve of the inside of the fuse. One other thing I would do differently would be to create the cover from fiberglass before cutting out the hatch. I'd layout the lines, cover the area with ultracoat, and then lay up 4 or so layers of 5 oz fiberglass that I could use to cut the hatch cover. This way, the hatch cover would match the curve of the fuselage perfectly. I would also recommend using this method for making the gear doors. Skin the bottom of the wing, then make a fiberglass layer that covers the entire area that the retract access and wheel wells will be, then use these for making your retract hatch covers and gear doors and they will match the curvature of the wing perfectly.

Scott

tfarmer96

thats a good price if you ask me. The great thing about those is you just have to run the airlines. Thats why i went with them. It didnt hurt that i had another plane for the others.

saramos

Well, here's the start of the hatch cover. First photo is of the accessories mounted. I've since glassed the fuse and filled the weave with primer and sanded the area smooth. To make the hatch, I first tack glued the material removed with a gap filling CA (second photo).
I then cut a piece of ultracote in a 5" square and taped it over the area with masking tape. I then hit it with a heat gun to pull any wrinkles out. I cut 4, 4" x 4" squares of 5 oz cloth, and 1 square of 1/2 oz cloth. I mixed up a batch of West Systems epoxy, using the slow hardener and added about 20% denatured alcohol. I used an acid brush and coated the area with epoxy. Then I laid the first cloth down and using more epoxy, fully whetted the cloth. I added a second layer of cloth brushing on more epoxy. I then used a piece of plastic to squeegee down the two layers, and remove excess epoxy. I added the next two layers in the same manor and again squeegeed the cloth. I finally added the last layer of 1/2 oz cloth, squeegeed the area, then brushed on a final coat of epoxy. (Third Photo)

Tomorrow should show the results.

Scott

w3po

Beautiful job Scott I might steal that idea.
Well looking at your pictures gave me an idea, so I dusted off the ol'camera and here are where I am so far
I used Tubig idea on the elevator shape
I have shaped and glued the top of the rudder then realixed the directions said not yet, well!!
The top fuse look OK I did not show the left side with the slight crack over the cawling, I guess it gives her characte
And finally the wing as 10 minutes ago.
Let me know if you see something massively wrong I appreciate it.
By the way if any of you are wondering Yes the workbench is a closet door complete with faux brass knob, nothing too good for this project.
Cheers from Maryland
Patrick

saramos

Well, made progress on the hatch.
Photo 1, I removed the fiberglass skin and mounted the balsa cutout onto it and trimmed it to within about 1/8". You can see where I made a flat to which the hinge will be mounted. It is tapered too, so the hinge line will be as close to the surface as possible.
Photo 2, a test fit.
Photo 3, This is a tool that I really like. it is a set of mini rabbiting bits. It will make 3 or 4 different size rabbits with an adjustable depth. I'll use this to create a recess around the hatch opening that the fiberglass skin will fit into.
Photos 4 & 5, I made a small template that matches the curve of the fuse. I only used this to draw lines that will be 1/32" past the balsa for a trim guide.
Photo 6, After trimming the fiberglass, I found the hatch opening was a little off.

Scott

saramos

Photo 1, I applied a mold release wax to the hatch around the edges, mixed up some epoxy with micro balloons, built up the rear and bottom edges of the hatch opening and pressed the hatch into place. I added a bit more epoxy mix to the outside of the bottom and rear seams and let it set.
Photo 2, I sanded the micro balloons flush once set. The door popped off easily leaving a seamless fit. Actually, the fit was a little too tight, so I sanded a little around the rear and bottom of the door for a little relief. I also trimmed back the balsa about 1/64" all away around. Here's the result of the micro balloons. Sorry that the photo is a little blurred.
Photo 3 & 4, Next I made the hinge from two Dubro pinned hinges. I removed the original pins and made a new one that goes through both hinges from piano wire. I covered the hinge joint with Vaseline and epoxied the hinge to a flat I sanded into the fuse, like the one sanded onto the back of the door. I also backed the hinge with a strip of 1/32 ply. This forms a pocket and should add strength to the hinge.
Photo 5, I added another strip of ply to the back side of the door to make a pocket, added epoxy to the hinge and pocket, slipped the door onto the hinges and taped the door shut to insure alignment as the epoxy set.
Photo 6, 7 & 8, Here is the door finally mounted, shown both open and shut. In photo 7, you can clearly see the ply strip that formed the pocket the hinge fits in. Notice in photo 8 that there ended up being a little gap between the top of the door and the opening. This was needed in order for the door to clear when open. If I could have gotten the hinge line above the surface, I would have been able to avoid the gap. In all, I am satisfied with the results.
All that's left is to add a magnetic latch, add some sort of handle to open the hatch, final finish and detail.

Scott

tfarmer96

you guys are killing me. Im stuck here in South America. That hatch is going to be great!

Bobman

My Feedback: (5)

Hey Scott,

Nice job on the hatch. For future reference, Nelson Hobbies (www.nelsonhobby.com) makes some really nice piano hinge material that's perfect for this type of application. I've also used BVM offset hinges with good success.

Got my temp workbench setup last night, trying to start the stab tonight.

Bob

w3po

Hello
Well I have framed the wings but now I have a basic question about the retracts.
I have pretty much decided as for my first kit in such a long time I will go the mechanical route. Now on all the retracts I have seen the actuator rod (I am not too sure of the semantic on this one but it is the rod which will be connected to the servo) is inline with the strut so it is pointing toward the wing tip. Well if I install the servo just forward of the one for the flaps, so amidship; how can I connect the actuator to the servo. I have looked at the metal pushrods which come with the kit for an idea on what to buy, but it seems to me that if I make a straight line tween the servo and the actuator then at the actuator the push and pull will not be linear. Now is there a semi soft cable I could buy, maybe guided at the retract by a pulley which could go from the servo, then loop around at the retract to be facing the actuator rod.
Sorry if it seems a bit a complicated explaination
As always thanks for your time
Cheers from Maryland
Patrick

tfarmer96

This problem is what pushed me into the air retracts. I bought the mechanicals and finally just decided the air retracts were an easier option. I couldn’t figure out the best place to mount the servo and the run the push rods. You could use nyrod but that still only gives limited flexibility. Its a tight fit anyway you go.

vasek

My Feedback: (4)

yup, on a Spit it's much better with air... on Robart HD's you can also switch the cylinder to the oposite side> for easy install mount the air tank and the valve & servo combo onto the center inner (top) wing section >no connectors needed

tfarmer96

Well boys it’s getting to that point where I need to make up my mind about an engine. I have been fighting with my self about which one and I thinks Scott has it right again with the RCV.

http://www.rcuniverse.com/product_gu...?engine_id=176

It depends on how heavy the spit is but I think I want a 120 RCV. Anyone out there have a 120 in a spit. I would like to know how it fits in the cowling and how do you have you cooling setup? Any pitfalls with this engine?

saramos

The cowl on the Spit is very narrow, and the 90SP is a tight fit. The 120 may not fit. Be sure to make careful measurements first. Also note that the drawings with dimensions that RCV has, does not include the carburetor. The mounting plate of the 90SP barely fits on the firewall at it's original height and width. You do have to extend the firewall box forward to accommodate the 90SP. If you do use it, I suggest getting the engine before building the fuselage, and carefully measure it's mounting position, then cut out new parts that make up the sides, top and bottom of the mount box. The mount box sides and wing saddles are a continuous piece and it would be best to cut new pieces from the appropriate ply for best structural strength. I build my fuse before figuring the mounting of the engine and had to add pieces to the front of the box. I ended up using some carbon I had, to wrap the box for strength.

Scott

tfarmer96

Covering the top of the fuse how did you guys decide how much to cut out around the cockpit?

saramos

I guestimated, ended up cutting off too much, and had to build it back up. I would recommend leaving A Lot of extra balsa, cut out the canopy, dry fit it, and draw a line around it. Then cut, say, a quarter of an inch inside the the line and trim it to fit when you finally are ready to mount the canopy.

Scott

tubig

that's pretty much how i did it. i would suggest not cutting the canopy out completely; leave, say, 1/8" to final trim later. other than that, ditto.