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Hammer F3 build (another another) - glider newbie

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MikeQ26/04/2019 22:05:02
96 forum posts
93 photos

Hello

been flying radio for years but never did anything with gliders for some reason. Anyway, I've been getting into it more this last year or so. Models include a Circle Dancer 3000, Fresh RES, Obelix, RC converted KK Caprice with ducted fan (less said the better about that one).

Recently piled my Obelix in so thought I'd replace it with a Hammer F3 as you do. I doubt I can add much compared to some of the other Hammer threads but thought I'd start one so I can ask obvious questions.

Any help appreciated.

Cheers

Mike

PS also waiting on a Sarik short kit for a PSS Canberra but that will be another thread. Plus I'll build a replacement Obelix as I still have the fuselage

MikeQ26/04/2019 22:11:43
96 forum posts
93 photos

Pics ... Hammer kit plus what's left of my Obelix, ready to rebuild, after radio failure sent it through a bush at high speed.

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There are no auxiliary wing joiners in the kit as per the list of contents. Are these just piano wire pins for alignment?

Also, the instructions say to cut the Ailerons and flaps off the wing and reattach with tape later. Is that right? They feel like they have hinges build in (peel ply or similar?). Don't feel like ailerons that you cut out on say a regular foam/veneer wing.

the wing joiner looks tiny ... is that right too?

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Edited By MikeQ on 26/04/2019 22:12:26

Edited By MikeQ on 26/04/2019 22:13:04

Trevor27/04/2019 08:46:27
avatar
365 forum posts
52 photos

Hello Mike. There should be a short length of (2mm?) carbon rod in there somewhere for the incidence keepers. If not, piano wire will be fine. They are indeed living hinges and should not be cut off! The hinge line does though need quite a bit of cleaning up to obtain sufficient flap movement.

The joiner is correct. I don't know why they leave the spar box so over-large.

If it helps, my build is here:

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

Have fun,

Trevor

Edited By Trevor on 27/04/2019 08:47:10

MikeQ27/04/2019 09:34:28
96 forum posts
93 photos

Hello Trevor

thanks for the feedback ... I assumed they were just pegs but thought it best to double check. Missing from kit but not an issue.

I've already bookmarked a bunch of Hammer builds including yours but will no doubt have more questions what with this being my first serious slope machine.

Cheers

Mike

Mike T28/04/2019 22:22:57
410 forum posts
28 photos

The joiner boxes are quite loose to make it easy to get the adhesive in and to cancel out any alignment errors when you bring the wings together while the epoxy is setting.

FWIW I baulked at the limited length of the wing joiner and got a length of Graupner 'blade-in-box' joiner from Gliders. Both my wings have the brass box!

MikeQ29/04/2019 07:07:51
96 forum posts
93 photos

Hello Mike

hows that work then? Are your two boxes 'straight across' ... as in, no dihedral between the actual boxes sitting inside the wing panels and hence no chamfering of the blade required. If so that would force the boxes 'higher up' in the slots, at the panel roots, given the dihedral of the actual panels? Otherwise you'd have to chamfer both sides of blade, which would leave empty spaces in the boxes so to speak.

I was wondering, with the way the instructions are, what happens if you end up bending the blade what with it being glued into the wing? But I guess if you get to that point the wings would probably be a write off anyway?

Cheers

Mike

Edited By MikeQ on 29/04/2019 07:09:04

Edited By MikeQ on 29/04/2019 07:09:51

Edited By MikeQ on 29/04/2019 07:10:59

MikeQ03/05/2019 14:16:52
96 forum posts
93 photos

Hello

looking at servos for the Hammer. Was thinking:

Vtail ... two of these ... https://www.hyperflight.co.uk/products.asp?code=BMS-125WV&name=blue-bird-bms-125wv-servo-6-2kg-cm-0-09s-11-3g-10mm

Ailerons and flaps ... four of these ...https://www.hyperflight.co.uk/products.asp?code=KST-DS135MG&name=kst-ds135mg-mini-wing-servo-5-2kg-cm-0-10s-23g-10mm

Size look right and torque at 5kg should be plenty? Overspecified or just about right?

Cheers

Mike

 

Edited By MikeQ on 03/05/2019 14:18:19

Mike T01/06/2019 14:29:07
410 forum posts
28 photos
Posted by MikeQ on 29/04/2019 07:07:51:

Hello Mike

hows that work then? Are your two boxes 'straight across' ... as in, no dihedral between the actual boxes sitting inside the wing panels and hence no chamfering of the blade required. If so that would force the boxes 'higher up' in the slots, at the panel roots, given the dihedral of the actual panels? Otherwise you'd have to chamfer both sides of blade, which would leave empty spaces in the boxes so to speak.

I was wondering, with the way the instructions are, what happens if you end up bending the blade what with it being glued into the wing? But I guess if you get to that point the wings would probably be a write off anyway?

Cheers

Mike

Edited By MikeQ on 29/04/2019 07:09:04

Edited By MikeQ on 29/04/2019 07:09:51

Edited By MikeQ on 29/04/2019 07:10:59

Sorry Mike - I've only spotted your question just now!

There is enough slack in the wing cavities to put the wing joiners in and still allow for a little 'cosmetic' dihedral.

IIRC, I cut the brass box to length (much longer than suggested in the instructions!), plugged the ends then epoxied it into both wings at the same time - not too much adhesive at this stage - just enough to hold everything in place. Leave a 5mm gap between the wing roots. When well set, hacksaw through the joiner box to separate the two wings. You can then put the wings on their tips and dribble epoxy into the voids around the joiner boxes - a heat gun helps. When that is done you can cut a well-fitting slot in the ply wing root ribs and epoxy these on. When that is done the ribs can be trimmed to profile and the edges of the joiner boxes filed/sanded flush. (NB - this assumes you've installed the wing bolt blocks first!). Then you can cut/fit the carbon incidence pegs (missing from my kit too!)

HTH

Mike

Mike T01/06/2019 14:34:17
410 forum posts
28 photos

Part 2!

The original importer of the Blejzyk kits (Rob from Flying Dog - now no longer about) insisted that the short, kit-provided box and bar was adequate. I just went a little bit further, to be sure...

If you manage to bend the vertical bar in this, then you're right, I reckon you have a write-off. To use an old aviation expression, "damage would be confined to the entire airframe"...

FWAL17/08/2019 14:51:36
avatar
314 forum posts
469 photos

Ballast.....The Hammer likes ballast!!!

MikeQ19/08/2019 18:12:30
96 forum posts
93 photos

Hello

managed to knock off a couple of projects ... an original Obelix and a new version one.

Time to start the Hammer. What with being a slope newbie I'll have lots of stupid questions.

Having researched the available Hammer threads I've now totally confused myself.

c1e68eee-db2d-4ff1-9dbd-c0284e57a956.jpg

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MikeQ20/08/2019 09:58:46
96 forum posts
93 photos

Hi

Q1) I've carefully tidied up the hinge line to open it out 1/16 of an inch underside. I'm getting 70degrees of down on Flaps and Ailerons and about 15degrees up on both ... without too much force having to be applied. Is at sufficient?

Q2) I'm using KST DS 135MG slim servos for ailerons and flaps. The servo leads aren't long enough. What's the usual form in glider world ... get the solder iron out and splice extensions. The foam channel in wing isn't big enough for a regular extension leads and their sockets.

Q3) I've seen wings using Deans connectors ... anyone got any advice. Being lazy, can check that out myself.

Q4) In the picture of the servo ... is there any advantage to having the servo arm further away from the hinge line or closer. Just thinking of the mechanical movement versus the geometry of the supplied servo horn in same pic.

Q5) How do you fix in place that kind of horn ... new to me. Is it a kind of fit and melt or glue thing?

Q6) I'm using Spektrum DX8 Tx. I'm thinking it should be possible to set up V-tail and CrowBraking? Probably going to revert back to Futaba at some point next year or the year after.

Q7) I'm going through a 'let's glass everything' phase ... mainly to skill up on glass/spray paint finishes. I'll have a decent amount of Oracolor left over, from a current project, for a nice paint scheme. So was thinking of glassing wings in lightweight cloth, SP113, peel ply and 2K Oracolor. Hopefully should keep weight down by only Using Paint on tips and LE. Is this a really stupid thing to do given that I read a lot about how Hammers love ballast!

Q8) If I did loose my bottle on the glassing option ...and go with a straight varnish ... what's recommended in the U.K.

Q9) Anyone 'modded' a Hammer for aerotow and is that a stupid idea full stop

Q10) The supplied snakes look a bit awkward re termination. I'd just use a Z bend at the tail end but look a bit flimsy up front for soldering a regular 2mm threaded coupler. Any ideas?

Q11) Am I OK to ask more questions

Cheers

Mike

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Edited By MikeQ on 20/08/2019 10:01:06

Trevor20/08/2019 10:36:42
avatar
365 forum posts
52 photos

Hello Mike. A few responses. Hopefully you will get a few more because a lot of the points you raise are matters of personal preference.

Q1. I haven’t measured mine but those movements sound okay.

Q2. Cut and solder.

Q3. I’d like to see some ideas on this. Because mine’s electrified, the servos and receiver occupy the space where the extension leads go and so I haven’t been able to devise a multiconnector solution that would still allow the receiver to be removed.

Q4. If you have any servo covers, the position of the pushrod shroud will probably determine which way round to fit the servo. Otherwise I don’t think it matters.

Q5. Fit and melt - but a bit of cyano wouldn’t go amiss. I have had one of them come loose.

Q6. I don’t do Spektrum. Sorry.

Q7. Mine’s film covered. The only ballast I carry is a slug of lead in the tail to offset the weight of the motor. We tend to fly from more modest hills so I haven’t felt the need for more weight.

Q8. I don’t do varnish!

Q9. The Hammer’s no thermal soarer so you’d need some good thermals to make aerotowing worthwhile. It is good fun though.

Q10. I used the supplied snakes with the integral nylon clevis at the rear and 2mm threaded adapters & metal clevises at the servo end for adjustment.

Q11. Yes - as long as you don’t expect to get clear and unambiguous answers

Trevor

MikeQ20/08/2019 10:56:10
96 forum posts
93 photos

Hello Trevor

thanks for the feedback.

Q12) I've seen on some threads where people have queried the actual position of the wing (LE as a reference point) versus incidence and effect on flight characteristics. The lower wing section and the moulded wing mount of fuse seem to match spot on with the LE of wings at lip of mount. Any feedback or experience on that score?

Cheers

Mike

Edited By MikeQ on 20/08/2019 10:56:24

Edited By MikeQ on 20/08/2019 10:56:57

Edited By MikeQ on 20/08/2019 10:57:29

MikeQ20/08/2019 12:18:00
96 forum posts
93 photos

Hi

first cuts ... knocked up a little tool out of a lolly pop and a 10A blade for cutting out e inserts. Had to shave 10A a little to fit rearmost position. Using Gorilla glue.

img_0973.jpg

Trevor20/08/2019 12:41:55
avatar
365 forum posts
52 photos

Looks promising. Make sure that the Gorilla glue can’t find its way through to the flap hinge!

I don’t recall any issue with the wing position.

Denis Watkins20/08/2019 13:28:35
3814 forum posts
54 photos

Crowbraking with the DX8

**LINK**

MikeQ21/08/2019 13:07:43
96 forum posts
93 photos

Thanks for links Denis ... will checkout.

Had this dremmel router attachment 25yrs forgotten  about  in back of a drawer. Brilliant for routing out foam. The number of times I should have used this but gouged away at stuff in the past.

img_0974.jpg

Edited By MikeQ on 21/08/2019 13:09:38

MikeQ05/09/2019 18:11:00
96 forum posts
93 photos

Hello

just thought I'd check out this crow braking malarkey before I start covering wings. I realise the Spektrum DX8 isn't ideal but I'm struggling to get it working.

Just thought I'd double check that the flap servos should be mounted as mirror images, as per ailerons. As in, the servo horns should be 'towards the tips' on both wings. Can get flap action right but mixing throttle as master to right flap causes left flap to move opposite way.

bit more reading I think.

img_0998.jpg

img_0999.jpg

MikeQ06/09/2019 12:14:16
96 forum posts
93 photos

Hi

making some headway on the CrowBraking and all that ... https://youtu.be/b5uuwhR2-5Q

Also, couple more questions.

Re Q2 earlier. I've just dismantled the connectors and inserted the pins ... pin to pin as a sliding fit. Then heatshrink. So it's a mechanical join as you would normally do with extensions I guess. Any opinions if this is a bad idea.

No experience of he kind of forces on the control surfaces for a model like this. Are regular 2mm threaded pushrods OK. Z bend one end and M2 Clecis other.

img_1001.jpg

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