Hammer F3F Another one Build Blog

[Peter Garsden]

Next the ailerons and flaps. I cut them off. The instructions say fill the hollows with epoxy and microballoons, but I think I will use finishing resin, simply because there is so much needed to fill the gaps in the leading edge of the moving parts and the wing. I don't think I have enough glue to fill it. We will see.

I also started to fit the servos by gluing the fibreglass cloth in place for a smooth surface to attach the servo supports. I used the sanding disc of my Proxxon mini tool

[FWAL]

Hi Peter

I'm sorry I don't understand some of the above post! Did you really cut the pre-hinged ailerons and flaps off. And the part about needing to fill the leading edges of the control surfaces. I don't remember having to do any of that. The finish on the wing looks nice though.

Mk

[Peter Garsden]

FWAL - I did cut the ailerons and flaps off because that was what the instructions say - I think you must have a previous version because they don't come prehinged any more. The instructions say use 2 layers of tape, one bottom and one top. I didn't fancy that idea so have gonve for silicone, which I find works a treat - see below. The pictures I list below should explain.

Any you are right about filling the leading edges - didn't read the instructions properly. One has to fill the ends of the ailerons and flaps with an Epoxy/Microballons mixture then sand it flat, which I have done.

[Peter Garsden]

Yesterday got up too early in the morning - too early but had to also go to the gym and fit in some flying at Bosley Cloud - from where one can see the scene of that awful explosion last week. The road, however, is closed from both ends. We usually go home that way, but not at the moment!

Decided to hinge the ailerons and flaps using silicone - something I have done many times before and it is a brilliant method, unless one tries it on smooth silicone surfaces in which case nothing sticks, at least that is my experience. Some very good articles on the subject - here for instance - http://www.rc-soar.com/tech/silicone.htm

Seems to have worked - I left the hinges for 24 hours to cure properly

The photos don't show but I used

A syringe with the nozzle filed down with a round file to fit over the hinge line.

Silicone I got from a car accessory shop which handily has a screw top to stop it going off

Edited By Peter Garsden on 26/07/2015 10:08:27

[Peter Garsden]

Next I decided to glue the fibreglass circles to the port wing as a surface to mount the servo trays. I made the school boy error of using evo-stick contact adhesive on foam - D'oh - should have realised it doesn't work, such a chump.

It melted all the foam down to the veneer, so I scrapped it off, sanded it down, and made a piece of 1/4 inch balsa to fill the gap - such a waste of effort.

On the other wing I had used foam2foam but was not such the joint was strong enough. Should have used PVA or Gorilla Glue - but was impatient and wanted an instant result.

Have glued the balsa in with foam safe cryano which hopefully will be OK.

[Peter Garsden]

More pictures of the hinge line with silicone applied. Stages are:-

1. Get a piece of 1mm ply and stick it in the gap between the edges.
2. Place a tab of masking tape at each end of the flap/aileron to hold it in position.
3. Cover the joint with masking tape and press down with your nail to adhere it properly - or get really good tape that sticks well (had a problem with the tape pulling off some of the fibreglass cloth so pull it off SLOWLY - it also stops it pulling off any silicone at the same time.
4. Put some silicone in your syringe which has a groove filed into one side to slip over the edge of the join.
5. Double back the aileron/flap as in the photo.
6. Squeeze a layer along the join then smooth down with wet fingers to create a thin layer.
7. Squeeze another layer over the top.
8. Fold back the aileron flap level.
9. Lay the wing flat to dry for 24 hours.

Voila a perfect very strong joint. I used silicone from a tube with a screw top so it doesn't go off.

Edited By Peter Garsden on 27/07/2015 09:14:40

[Peter Garsden]

Have also cut out a piece of 6mm ply - the other blog suggested 9mm, but I only had 6 and thought that would be strong enough - to line the under wing fuselage.

The kit suggests two small pieces of 3mm ply positioned at front and back, which may not be strong enough in the event of a heavy impact.

I used doubled sided tape to place the wing in the correct position whilst I drilled firstly the pilot holes, and secondly the 7mm holes for the nuts, which are not the standard 4 poled spike grab nuts but thinner nuts with a threaded hole cut out of a tube I have never seen before.

[Tim Mackey]

Great blog Peter and nice pictures to accompany it too - well done that man.

[Trevor]

Thanks for all the pictures Peter, especially the tutorial on silicone hinging which I have heard about but never tried. I'm surprised that Blejzyk have given up on the living hinges. Okay, they needed a bit of cleaning up, especially to get the flaps to go down far enough, and film-covering the wings with the control surfaces already attached is never ideal but overall, I thought this was a positive feature.

My kit had two ply blocks for mounting the wing retaining nuts as you mention, but they were nearer 6mm than 3mm thick. The nuts themselves were new to me too, but I'm not sure they match your description either! You can see them in one of the photos here:

http://www.bartonhewsons.uk/home/modelflying/soarers/blejzykhammerpro.html

All in all, it sounds as if there has been a fairly significant revision to this kit. I don't know whether Rob can clarify whether this is specific to the Hammer or whether the whole range has had a makeover?

Trevor

[Peter Garsden]

Thanks Tim you need to get started on yours.

Trevor I struggled with the type of hinge the Hammer used to have on my Voltij so I think I prefer this method. There was talk of the same problem on the other blog.

This photo shows how I lined up the plywood base to drill the holes

Edited By Peter Garsden on 27/07/2015 20:08:59

Edited By Peter Garsden on 27/07/2015 20:14:14

[Peter Garsden]

After all my talk about silicone hinge the flap on one side has come off and will need redoing.

I think it is because the silicone did not seep into the gap at one end and it came under some sideways stress when I was drilling the holes for the wing bolts. It doesn't stand sideways movement and can tear off - something that doesn't happen when the moving parts are attached.

I will tape up the parts so they don't flap around.

[rob piec]

Hi guys.

I'm the flying-dog man

I built quite a few hammers and I'll be happy to answer any questions regarding the build.

The ailerons and flaps are hinged. Blejzyk sells 2 versions so called high and low.

I sell only the high version. (but even the "low" one has the hinge already in - just needs cutting the venier skin - same production method as most mouldies )

I will share a few tips with you in the next few days that should make the job easier

[Peter Garsden]

Oh dear does that mean I have cut them off when I shouldn't have done? I must check the instructions again. I am convinced it said cut them off and tape them top and bottom.

[rob piec]

Affraid so Peter.

But thats not a big problem to rehinge it.

I'm bit out of time but will make a few pictures soon and will share a few ideas here.

[Peter Garsden]

Rob - I am bemused because I have looked at the instructions which clearly tell you to cut off the ailerons and flaps, then re-apply them with clear tape top and bottom, so I still not convinced.

I quote "Cut out the ailerons and flaps with a sharp hobby knife. ....Ailerons and flaps can be attached with a clear tape. When attaching ailerons start at the top surface and then turn the aileron flat on the top of the wing. Tape the bottom surface. When attaching flaps start at the bottom surface and then turn the flaps flat on the bottom surface of the wing. Tape the top surface. "

That seems pretty clear to me - this is the link to the instructions **LINK** - perhaps have a word with Artur?

I agree that the elevators are pre-hinged and fine but not the wing I don't think, but I am probably wrong.

The ailerons and flaps in particular seemed too stiff to be able to hinge through 90 degrees for air braking

[Peter Garsden]

Back to the plot - have glued the ply under wing plate with conventional Araldite which hopefully will have secured it to the fibreglass strongly enough. I used some plastic to line the holes then screwed it on. I managed to break one plastic bolt in the process by tightening it too much, but I think it is fine.

I had a devil of a job opening out the holes to take the plastic sleeves, which are a really good idea. I tried a large drill which was too severe, then a Dremmel tool which burned out. Anyone got any tips?

[Peter Garsden]

Also made the suggested cardboard template last night and glued up the tailplane. I am going for the 4mm bolted version, which is a bit safer on a heavy landing to me.

As suggested elsewhere I have glued in a fillet to take the bolts.

I used a bit too much 5 minute epoxy but it will be rite. Pinned everything down whilst it set. Have put some nice balsa filler in the cracks to smooth up the joins

[Andy Meade]

Pete - for the holes how about a sharpened brass tube? I have 4 in different sizes that always cut cleanly through veneer, foam, and balsa.

[Peter Garsden]

Andy - nice one - how do you get a brass tube with a large diameter into the chuck of a drill - or do you just use it manually? What do you sharpen to the tube with? A round metal file?

Well the instructions said just glue a very thin piece of plywood under the tailplane seat then put holes in it of 4mm to take the plastic bolts. Did that, but very difficult to attach inside due to inaccessibility. It came off when I tried to drill the holes.

Also the nuts are about 6mm deep so I have made a sandwich of wider 1/64th ply and 3mm balsa to hold the nut, otherwise it would stick up into the tailplane. I want it to snap on impact not rip holes in the tailplane

[Peter Garsden]

I drilled the holes for the bolts from the top in the middle, but the holes were over to one side because the base was slightly askew. I decided to refill with epoxy putty and let it go hard then redrill from the bottom. Love the white epoxy putty, as it is easy to paint and fills repair holes very well.

[Peter Garsden]

Also this morning, I lined up my ballast tube which is 20mm internal carbon and which I sourced from T9 Hobby Sport. It needed the end blocking so I wrapped it with carbon tow and resin, then put a balloon over the top to keep it down.

I then put my slugs (shower rail cut up and filled with lead) into the tube and marked the balance point. I then lined that up with the C of G, and noticed that it was too long. It protruded into the servo bay too far as I thought.

So instead of 10 slugs, it will only take 8 but that is fine as I rarely load up with maximum weight.

[Andy Meade]

Pete - yup just sharpen on the inside with a round file, then twist and push it through. If going through foam you can push quite hard, but slow down and twist more than push when coming to veneer.

[Chris Barlow]

To sharpen brass tube I use a cone shaped die grinding bit in a Dremel...

Not much use if your Dremel is burnt out though, sorry!

Looks like a nice bit of kit for the money Peter.

[rob piec]

1: the wing seat reinforcement.

plywood - thickness - just to get the nuts nicely in .

The small pieces included in the KIT are just fine. This is what I used in my private hammer I built over 3 years ago. Never any problems even after a few heavy landings.

2: tail snake exits.

two ways of doing it.

exit inside the fus

or outside

I like the second way as it just stronger where the horns go - more material and moved away from the edges.

never heard of any breaking there tho . for the smaller models I go with the inside snakes. Sanding of some balsa at the joint of V-Tail halves might be needed if you want to go with the inside exit.

PS - angle between halves - 110 recomended by manual.

As you can see I got bolts on the inside and "screw in nuts" in the V tail. I will search for more pictures of that - nice looking- takes time to do it.

3: Snakes.

snakes can boil your blood... so here is a little tip how to make job easy and clean.

you need epoxy 15 min or slower, neodymium magnets and cling film.

Mix epoxy - add some aeroseal or microbaloons if its too runny.

spread on the snake - put inside the fuss and secure with the magnets.

Of course you need to decide where the snake will go first

Hope that helps with a few bits.

If you have any questions please ask guys.

few more tips soon .

We will make new build manuals for Blejzyk and for all the models but it will take time and at the moment I don't have enough time to even start with it

have a great weekend

Rob

[Peter Garsden]

Rob - thank you very much - very helpful. Think I am clear, but just in case:-

1. I presume that the magnets attach to the wire in the middle of the snake? Very clever idea.
2. What is the cling film for - to keep the magnets in position and stop them dropping off?
3. I have seen someone use circles of balsa to hold the snakes in position and was going to use that method but this seems more reliable.
4. I think I will mix the epoxy with fibreglass flakes as I think that adheres to fibreglass better.
5. I was going to go with method 2 for the tailplane.

Clevises

1. How do you attach an adjustable clevis to the snake at the servo end - that was what was baffling me?

I am sure you are very busy and appreciate you taking the time to help.