RE: BVM T-33 AFS Build thread
 

Iceman....
Start with 80 PSI and go up to 100 if necessary.
I am not familiar with Hitec, do a cross-reference with JR to match up the torque requirements.
Control throws-start with....
Rudder-3/4" measured at the base
Elevator- 5/8" at root
Ailerons- 5/8" at inboard edge

Hope this helps

RE: BVM T-33 AFS Build thread
 

Gazzer,

Your wing gap is fairly normal, there is a simple solution to the fit. You will use a product like Evercoat polyester glazing putty, or lately I have been using polyfiber superfill (available online from Aircraft Spruce) Start with the fuselage wing root, add some clear plastic wrap or wide masking tape. I usually start with the plastic wrap, tape it in place over the wing filet end. The reason I like the poly fiber is it is a slow set so it gives me time to work. Mix up a good sized batch of it and "butter" it onto the wing root. Next slide the wing onto the tubes and mate it up to the fuselage. I might add you should have already installed the wing bolts etc... so that you can fix it in place while the putty cures. I usually add some masking tape about a 1/4" fromt the edge of the wing root so I can pull this up before the putty sets up to reduce the amount I have to sand. The other key step is do all of this AFTER you have glassed the wings, you want the surface to be fairly toguh for all the sanding you will have to do on the putty. I will try to post a picture of a couple of the seams I have on my airplanes. By doing this a couple of times you can make a gap disappear. I usually switch to parting wax after the first application of putty to really make a tight fit.

RE: BVM T-33 AFS Build thread
 

Darn digital camera,

Managed to displace the images, user error!!

Right,

Did have an image of the Bird with her feet down, wheels temporarily attached and a bit of tape to hold the tail section on. Looked like an aircraft and rather larger than I expected. I do like it you know!!

Now the progress will look a lot slower, and probably be a lot slower, it is all the fiddly bits now.

Remounted the speed brakes, they seem a little too easy to wobble on the main pin linking the carbon hinges, and even with the air cylinder attached don't always centre properly. I think a few shims maybe neccesary.

Started to cut out the doors on the F/G belly pan moulding. Happy with the lines, but the cut is wider than I thought, but should function cleanly, and in the future I could always get another moulding.

What sort of gap do the good builders get for wheel doors and the like. I estimate that my gap is about 2mm, maybe 2.5, is that good bad poor or indifferent??

Ignored BV's instructions for the epoxy engine bypass and used a spray on filler/primer...... don't ignore BV, still have lots of filling to do, oh well!!

Found my Aeropoxy gun sticking up, seems like I must have mixed the two compounds when replacing the lid on the epoxy tubes, manged to clear them out though!

So, with a bit of luck can focus on mounting the doors tonight, seems like quite a long fiddly job but will look nice when complete.

Have finished and tested the Kevlar fuel cells, with no leaks eh?!!

I take it the small black hex headed screws are the poly ply screws?

Wish I had another larger table to work on, the one I have is a little small and round, an oblong one would be much better.

Best go and see if I can sneak out again tonight!!

Gazzer

RE: BVM T-33 AFS Build thread
 

Mark,
Thanks for the info. If i move the surfaces with my hand they move the measurements that you gave me and no more. Is this a build error? are tey supposed to move more than that so you can set the throws up in the radio?

Thanks
John

RE: BVM T-33 AFS Build thread
 

Thanks DavidR,

Makes me feel better, I managed to get an even better fit, as a bit of rogue moulding was on the wing stub so having sanded it off, it mates better. Looking at the models in the magazines, though, they are virtually invisible so your tip shows how you do it!!! Will have a go, do you know of the UK equivalent name for the putty?

Also be very interested in the gaps you would expect around the gear doors, I wonder if my dremel cut off disk was bigger than it might have been!!!

I am assuming I should not be over worried about it, not likley to ruin its flying abilities is it?

Thanks again guys, really learning and enjoying your support,

Gazzer

RE: BVM T-33 AFS Build thread
 

A few piccies,

Tell me if you would are these gaps between fixed and moving surfaces about right or a bit big?


Gazzer

RE: BVM T-33 AFS Build thread
 

hey bro'

another method to help with a nice tight fit between the wing and fuse is as follows:

use clear plastic wrap (saran wrap or similiar) placed over the stub on the fuse. stretch it taught (no wrinkles) and tape it down so it doesn't move. with your previously glassed wings, run a bead of aeropoxy on the wing root face
smoothly and with even pressure install the wing.
the aeropoxy will ooze evenly across the root face and will provide a nice even face between the mating surfaces.
any areas that are not evenly spaced can be fixed by dabbing some aeropoxy onto those areas.

Tape placed 1/8"-1/4" from the wing root face on top and bottom of wing will help minimize excess aeropoxy and will allow a smoother transition between aeropoxy and wing surface.

RE: BVM T-33 AFS Build thread
 

Gazzer,

I cut all of my doors etc.... out with a razor saw. I tape a stell machinist ruler down to the surface and carefully and slowly cut the doors, etc.. out. I use the CA trick to fix my screw ups but I try not to make a large gap in the first place. I also several years ago ditched the dremel cutoff disks and started using a diamond blade, much thinner cut, and it won't shatter and send hot pieces of cutoff disk flying down shirts, or inside your shoes (once had a piece make it under the tongue of a deck shoe, I had on no socks and had a crescent shaped burn for a couple of weeks!) That being said your gear doors will be fine and won't bind with your gaps, I usually get mine tighter. I will pst those pics within the hour.

RE: BVM T-33 AFS Build thread
 

A couple more

RE: BVM T-33 AFS Build thread
 

AHHHH so this thread is where the builders hang out! Nice!

As for hatch fits and cutting out doors and such, practice helps.


I use a technique similar to David.

First, I place a piece of tape near the line I want to cut, maybe 1/16 inch away from it.

I like to use 3M blue masking tape exclusively now, it leave very little residue (none?) and it will still pull up cleanly after a long time

RE: BVM T-33 AFS Build thread
 

Next I place a piece of brass strip (maybe 1/4 inch wide and 3/32 thick) on the tape, butted RIGHT UP to the line I want to cut. I can even bend the brass to match any curve of the part I am cutting. I then glue the side of the strip to the tape.

RE: BVM T-33 AFS Build thread
 

Then I cut on the line with a razor saw. Start with little small strokes till you penetrate the surface. To clean up the corner cuts, I have saws that I have removed the backs from.

I like David's way it is a bit easier than my way


BTW this tape and glue technique is great to temporarily clamp things down, the next picture shows me gluing the servo mount into a bandit wing, with a little popsicle stick glued to the blue tape and a kind of clamp

RE: BVM T-33 AFS Build thread
 

Thanks guys,


I used the razor saw method for the nose gear and speed brakes, although not with tape and the brass guide. That really is a better way.

The belly pan is quite a complex moulding, and has lots of contours, I couldn't see how to cut with a razor saw, but I can now!!!

When I have finished the fitting of these panels and doors, I think I will do as previously suggested and build up the edges with either "kicked" cyano or a littel Aeropoxy using the plastic food wrap idea to prevent re joining. Then my trusty permagrit tools can nick off the 1 mm or so needed to make sure the panels and doors open/close properly.

So, no one has gone "tut, tut" you "need" to sort the gaps out, but I have some better ideas of how to do things!!

A few days now before I get another bit of a build, so any more hints and tips greatly appreciated!!

Cheers,

Gazzer

RE: BVM T-33 AFS Build thread
 

Matt touched on peeling the back off a razor saw but to carry that one step further I have done that with several saws and have even trimmed some of those saws down to make them work better in tight, or curved areas. Also if you have not used any of the permagrit flexible strips pick some of those up. Cut them into small strips and they can be bent to conform to whatever shape you need.

The other thing to mention is once you cut a hatch out drizzle some thing CA onto the edges, this keeps the edge from getting so bunged up when handleing it.

RE: BVM T-33 AFS Build thread
 

Thanks DavidR,

Another useful tip!!

One query I mentioned in respect to the speed brake doors if I may?

These seem to flex quite a lot on the hinge and don't seem to fully mate up to the opening, although a little manipulation gets them close up where they should be.

The hinge has a pin through it, through the two carbon hinge legs, and you tighten a collet either side of the hinge. These collets seem to be as tight as I can get them, but there is still a bit of a gap, hence allowing the speed brake doors "to wander slightly".

Any idea of how to minimise this? The hinge etc, was all glued up before the doors were removed, so i was quite surprised at this problem.

Gazzer

RE: BVM T-33 AFS Build thread
 

Where is the gap? In the hinge assembly itself?

I have not built one of the T-33's but if I am not mistaken the hinging is similar to the hinging on the F-100 speed brake. What I did on the F-100 is repalaced the two short pins with a single pin that goes through both of the hinge points. I also had to tweak the edge of the speed brake door slightly with a heat gun. On the F-100 the air cylinders do not have a mechanical advantage so the hinging, and the way that the brake fits to the fuselage has to be perfect or the brake wil not seat correctly when it is retracted. I also don't hesitate to add doublers, or braces inside the fuselage to make sure there is no flexing going on. Using the F-100 as an example again, when the speed brake is retracted the cylinders pull the door towards the rear of the fuselage, I made sure the doublers that put on the hige anchor point in the fuselage were drilled before I added them and then I installed the cylinders and added air pressure to them then pulled the door as far forward as I could and glued them in place. That way when the cylinders pull the door backward (and I am talking in thousands of an inch here) it does not bind up.

RE: BVM T-33 AFS Build thread
 

Gazzer,

I don't have the manual on the T-33 and was wondering if you could tell me where the CG is supposed to be on this bird.

Thanks
John

RE: BVM T-33 AFS Build thread
 

From your description, the movable part is "floating" along the hinge pin too much? Sorry I am having trouble visualizing it. Can you post a picture of this hinge?

If it is what I am thinking, then extend the hinge pin enough to put a sort of "thrust bearing" between the wheel collar(s) and the hinge. I have used washers with a piece of fuel tubing between them, over the hinge pin.

I may be way off on this so post a pic and we can come up with something. I did not think the T-33 speed boards were in line so I am not sure you can link the hinges together like David is saying....where is Mark Taylor? on this You gotta keep these BVM reps on a short leash!

RE: BVM T-33 AFS Build thread
 

Matt,


You can always bend the pin, or maybe even add a second hinge block and extend the hinge pin, anything that fixes the location of the hinge line.


What leash......I'm like a mangy dog.....I keep chewing through my leash!

RE: BVM T-33 AFS Build thread
 

Mr Matt,

I think your idea will suit, I will try and take a picture, or might even draw it and post it up, but it might be awkward to photograph, but your explanation makes sense to me.

David R,

See where your coming from and a brace might be the best way. I glued these in place with the hinges set before I cut the doors free, so in theory, they should be 100%, but can't get the collets flush to the hinge arm. I guess there may be a little stray aeropoxy fillet, that might be binding on the collet.

That said, a brace would suite quite well, mechanically simple to install.

Iceman,

Will look up the Cof G for you, PM me with your email address, I have an idea!!

Gazzer

RE: BVM T-33 AFS Build thread
 

mr-Matt,

Our posts crossed, the second hinge block is my favourite idea!

Will try and post the piccie but off out shortly!!

Thanks again guys, I am honestly really grateful for your help and interest. It is so good to feel that I am not embarrasing myself and improving in knowledge and hopefully skills, making this investment such fun.

I am indebted!!

Cheers,

Gazzer

RE: BVM T-33 AFS Build thread
 

That was David's idea, but if it works I will take the credit.

As to the questions, these are my favorite threads, seeing how people build......it seems that part of the hobby is going away, it is all either ARFs or some professionally built model that someone buys....

RE: BVM T-33 AFS Build thread
 

Amen brutha! When I first started modelling there were no such thing as Arf's it's a shame to see it, I go to the local field and everyone there is flying some sort of arf model. The true builders are becaoming an extinct breed.


BTW take the credit.....I probably stole the idea from someone else anyway!

RE: BVM T-33 AFS Build thread
 

Of course my Dad sees a BVM kit and he calls it an ARF, he is used to a box of sticks, waxed paper over plans, a pin cushion full of pins and white glue!!

Hey Gazzer where are the pics, man?

Here is a pic of the hatch gap on my Stingray I will never finish. I use hysol 9462 for filler (very hard) and mold release wax to blend in surfaces like hatches. It might work on your doors too

RE: BVM T-33 AFS Build thread
 

[quote]ORIGINAL: DavidR


Took the words right out of my mouth!