I am looking for a reliable, safe, secure and neat way to fit the main hatch on a BVM MiG15.

Currently I am planning on having two locating pins mounted at the forward edge of the hatch, securing into the rear of the cockpit x-brace which is part of the fuselage moulding, then at the rear possibly two of those sprung canopy hatch pins, locating into the rear fuselage section - this however will leave two wire 'lugs' sticking out from the top of the rear hatch, but as I see it there is no rear option here[&o]

The main problem is in the hatch mid-section. The fuselage hatch is long (see pic) and in the middle it tends to flex, and not lay completely flush with the fuselage, so really there needs to be a simple securing system fitted in this area (see close up of area for securing hatch centre section pic).

I have considered magnets, although achieving the correct 'pull' and release to allow securing and removal is a bit hit and miss, I have considered a sprung catch using bent piano wire, locating in a slot cut into the lip on the fuselage top, again not sure on the effectiveness.

Do all you experts have any ideas, I really need something which is 'concealed' and not visible from the outside - any ideas really appreciated.

Marc.

You could always fabricate a "L" shaped piece of plywood (or composite material) and have it slide into place (its glued to the hatch) into a slot in the fuse, one on each side, that sucker will keep the mid section down, but this only works if you have room to slide the hatch back when wanting to remove it, and im not sure if thats your case ?

Thats the problem, no room to slide back, but thanks for the input.

How about stifening the hatch with some CF cloth inside, to avoid flexing ?

Yep, thought about this as well, it will probably help but not sure it would hold the panel closed and in line sufficiently during flight etc as the fuselage flexes etc - I'm only assuming here though as I am a 'rookie' to building jets, please correct me if I'm wrong.

I use poly ply tabs to keep the center part of most of my hatches flush th the edge of the fuselage. Set the poly ply into the hatch tack it with CA then aeropoxy them into place. Measure and cut you slot in the fuse and adjust if necessary fo ra good fit. Round the edges on the tab so it slips in and out of th slot easily. If the hatch tries to flatten out you can always add a small ply former.

DR

For a more concealed mechanism for the rear pins - this is what I did on my Hunter: http://www.rcuniverse.com/forum/fb.asp?m=3538275 - perhaps you could adapt that somehow.

For the spreading issue - on long hatches I usually use a combination - tabs as David suggested, and sometimes also a threaded pushrod that just connects from one side of the hatch / fuselage to the other (turning a clevis in or out a bit allows for adjustment of the "pull").

Gordon, very neat, seen something like this on a MiG15 build thread somewhere but cannot place it so this has helped me - cheers.

I am going to try to workout a system similar to this and will post on my BVM Mig 15 build thread if it works out

Any other ideas are still welcome please.

Difficult to explain but I like the Yellow F15 hatch method.

Two long piano wires, through tubes that start somewhere convienent near the cockpit with a small right angle bend to pull on. The wire and tube is through the fuselage into a tube in the hatch to the back of the hatch and out into the rear fuselage tube. I did the same on an F16 and used poly tabs as well on the side to ensure alignment

works 100%

Hope this make sense, if not I will take some pictures

Ian

Does the hatch have to slide forward to lock in or does it drop down vertically? I have a good technique if it drops down vertically or close to it.

Matt, I'm all ears on your method if you care to explain in great detail. My new megabar, I have a fairly good method, but always looking for improvement, and it is a drop straight down hatch.

Matt, to be honest its likely to be a drop in so any tips and methods would be greatly appreciated.

Ian, this method is used to secure the front nose hatch on the BVM MiG15, and works well, problem is I cannot get anymore cables or snakes into the engine bay area, its full to bursting! If I could the cockpit area is also full to bursting - this kit is really tight on space.

Appreciate the feedback though, it is a great method and works a treat.

Ok

I was not aware of the front hatch on the Mig.

I will be interested in Matt's method, always looking for solutions even for the next problem!!

Ian

Ok my wife sent me a couple of pics that sort of show the technique. I learned it from Kent Nogy I think.

My technique is to put a large threaded ball (generally with 4-40 threads) screwed into a blind nut (t nut) embedded into the flange of the hatch, maybe 3/8 of an inch from the edge (the distance depends on the slope of the hatch at that spot).

On the fuselage side, I install 2 music wires, maybe .075'' diameter, maybe 2 inches long, spaced just about the width of the shaft on the ball.

Now the way I do it, is to inset the 2 wires into slots I have milled into a couple of pieces of 1/8" ply (maybe 1/2 inch square). I CA the wires into the slots, then I keep checking the tension by snapping the 2 wires onto the ball from underneath the hatch opening (with the hatch installed obviously). You keep belt sanding the top of the little ply tabs holding the wires until the fit is tight. You should get a very nice tight SNAP action when you have it right.

After everything fits I epoxy the wire assemblies into the fuse with the hatch installed to make sure everything lines up. You can make slight adjustments by bending the wires.

marc s, you building is gorgeous, how do you make those sheetmetal brackets? Do you have a little press brake or something?


BTW, before I forget, Gordon's idea of a tensioner between the to sides will work, as will a rib.

Nice ! Thanks for the pics Matt.

Matt,

Great system, this will save me some grey matter

Regards the 'sheetmetal' brackets, not sure which items you are refering to, I don't have any specialist machines just a 'Dremel' and the regular stash of tools. If you let me know what items you are thinking of I will send you info on the construction method.

Cheers

Marc.

Hi Marc,
first i must say you are doing a AWSOME job---- i have a Mig 15 kit also and am following what your doing with great interest--- mine is a AFS wing---

Have you seen the pics of the silver one for sale on BVMs web site ??? it has a hatch with a conceled latch system--- shall try to attach a pic---
If you go to http://www.bvmjets.com/ and go to turn key jets--- scroll down and click on the pic of the silver Mig 15--- lots of scale detail and ideas---- the hatch has inside cables you can just make out to pull the latches open from the inside---
cheers Jay.

Now thats very cool, probably more than I could wish to achieve but like the principle.

I have worked out and fitted a 'mid section' alignment system to hold the cover in the right place, now I have to decide on how the canopy comes off, it is likely that I will have to make the canopy easily removable, as the cover will need to be lifted straight off rather than backwards.

I could cut a section out of the cover to match the canopy, but this will cause a few more issues with the confines of the space at the front of the cover and just rearward of the canopy. Below the rear canopy I have all the air valves and regulators/restrictors and the two fuel shut off valves so want to keep this area accessible.

I have some great ideas to work from now, so cheers for the input and pics, will post the results on the build thread.

Marc.

When you going to finish that thing??

Rory, where in the world are you now?

Regards the MiG, don't rush an artist