Hurricane Building Tips and Plan/Woodpack queries

[Phil Cooke]

Chris - measured F1a diameter this evening at 65mm dia, not tested it with the vac form yet, but might need a little lick with the sanding block to slip inside?

[Peter Garsden]

Phil - before I start on the wings - I know everyone does the fuselage first, but I don't, and it makes for a worrying voyage of discovery - I have been looking at the plan and notice that the wing section is semi-symmetrical so:-

1. You would normally build this with tabs to support the trailing edge, as otherwise the ribs could be out of alignment.
2. You said that there would be no article to help, and the build notes only refer to the fuselage.
3. Previously we built on the wing bottom skin but this does not appear possible with this wing section.
4. I was thinking one would start with the top and bottom spars, but how to support the trailing edge? Packing piece of say 1/4 square?

[Phil Cooke]

Hi Pete,

I haven't built a wing yet, the beta test work I performed focused solely at the fuselage - hence my lack of notes on the wing. We will need Matts input on the wing if there are any complications or specific issues to be wary of, but I really don't think there are!??

From what I know of the prototype I can state it WAS CERTAINLY built onto the lower wing sheeting just like the A-4 and the JP before it... the semi-symmetrical wing section lends itself well to this as it is almost a flat bottomed section between the lower wing spar and the sub trailing edge. I'm pretty sure its just built with this section of each rib flat mounted on the board which then dictates the rib angle and raised the front...worst case we need to raise the skins with a little chock along the sub-TE as you've suggested and mount the ribs into that 'cradle', but I'll have to check the parts to make myself sure that's needed?

I'll see if I can crib any build tips from Matt on this part of the journey as he's no longer active in the forum

[Phil Cooke]

Hi Pete,

I've double checked with Matt, and my thoughts are confirmed, there is no need for any chocks under ribs or under the lower wing skin, simply pin the lower sheet down on the board, add the lower spar and build the ribs flat onto the board so their T/E are in contact with the skin - effectively treating that section of rib as flat.

This naturally raises all the rib L/E - so once the sub TE is added you have to roll the sheet around the underside of each rib at the front - just like we did on the A4.

[Phil Cooke]

A diagram to help if needed - taken from the 'typical section' view on the plan with a 'board' added to show its as good as straight between the lower spar and the T/E stock mounted on top of the skins - hence why this method of assembly is fine.

[Peter Garsden]

Excellent and over and beyond the call of duty again Phil, fabulous and very helpful.

[Bryan Tucker]

Hi guys, I have being working on the fuz and just got the part where you dry fit the snakes and fit the servo plates for elevator (and rudder in my case). I pushed a standard servo through the servo mounting plate as shown on the plan and offered it it up on top of the 1/2" x 1/8" fuz stringer. The servo is going to stick out by about 7 or 8mm above where the side skin will be bent over between F3 & F4. The servo plate can't be moved nearer the fuz centre because it will stop the battery from being able to slide into the battery box. If you lower the ply servo plate to below the stringer then the snake alignment is way out of line.

My solution is to use smaller servos eg Hitec HS-82MG and make some new ply servo plates.

[Phil Cooke]

Hi Bryan,

I noticed the servo came very close in my build, in fact one corner just touched the sheeting as it rolled around F3 and F4, but it's in and built as per the plan with the servo tray on the top face of the doubler. I'm using a std size Savox servo - maybe yours is a little deeper than std size? A 7 or 8mm clash sounds an awful lot to me.

Edited By Phil Cooke on 13/04/2018 14:56:58

[Peter Garsden]

While we are on the subject of snakes Phil, I was wondering how you managed to drill holes for the snakes in the formers when they were in situ, or did you drill the holes before they went in? You couldn't really do that because you wouldn't know how to line them up?

Also how does the snake attach to the elevator - a piece of brass flattened tubing attached to the joiner and soldered and a clevis a la the JP?

[Bryan Tucker]

Hi Phil

Thanks for the feedback and picture of your servo. Mine must be taller although it is exactly the same size as the one one in the side elevation on the plan and I've re-measured it and it is 5mm above the inside of the skin not 7 or 8mm, sorry, but still too tall. Anyway I have ordered smaller servos and cut the servo plates to suit. Lucky there is loads of spare light ply on the laser cut sheets.

[Phil Cooke]

Pete - I drilled F9 and F8 with a central snake mount hole prior to fitting them. The snake outer is then retained in both as well as F7 (as per the kit) and F4 (extender mount fitted once in situ)

Yes Ill make a similar horn to the JP and A4, although it needs to be as slim as poss - will have to get the brazing kit out!

[Peter Garsden]

See my blog for queries about the aileron torque rods and straddling the dihedral Phil. Query please.

Edited By Peter Garsden on 24/04/2018 17:39:50

[Trevor]

I’ve just received my kit (which seems to be nicely cut from good quality wood) and am just beginning to study the plan before ordering the necessary sheet/strip wood and other bits and pieces.

Looking at the length (and weight) of the aileron torque rods, I was wondering about putting servos in the outer panels instead. The wing section is deep enough so am I right in thinking that the preference for torque rods is solely to avoid having any linkage protruding from the underside to get snagged on landing?

Trevor

[Phil Cooke]

Yes nothing more than that really Trevor - just the quest for scale - there is an argument that internal linkages are more robust for the slope too, but with small metal geared servos there is nothing wrong with going as you suggest with short linkages from servos mounted in the outer panels... up to you whether you exit them on the top side (better for landing on the slope) or the underside (better for scale appearance)

[Stephen Bowdler]

I will mount my servos in the wing - between R4 and R5. I have bought a pair of MKS6100 servos and the matching Integrated Drive System so the whole servo / linkage / horn will be inside the wing. Maximum height is around 16mm.

[Callsign Tarnish]

Stephen, they look nice but I can't see the benefit unless I've missed something? The same end result can be achieved with torque rods and cheaper servos in the fuselage?

[Trevor]

Very nice Stephen, but I must admit that I was thinking more along the lines of the Corona DS-939MG at a fiver apiece! If it really needs something skinnier, I could push the boat out and go for the DS-239MG @ £7.50. And no, I don’t understand the numbering system either!

Trevor

[Stephen Bowdler]

It's just a matter of personal preference. I don't like torque rods and one servo because I never get them perfectly symmetrical so end up using two servos. If I use two servos why not put them in the wing? I've used this servo and linkage before and they really do give a slop free, precise movement with nothing sticking out of the wing.

[Callsign Tarnish]

Posted by Stephen Bowdler on 26/04/2018 15:46:26:

It's just a matter of personal preference. I don't like torque rods and one servo because I never get them perfectly symmetrical so end up using two servos. If I use two servos why not put them in the wing? I've used this servo and linkage before and they really do give a slop free, precise movement with nothing sticking out of the wing.

Fair points. Playing Devil's advocate the wing might be heavier (2 x hatches and more complex servo mounts?) but then no long, heavy torque rods. You will have more weight away from the C/L though which will dampen roll authority, admittedly probably not to a degree we're likely to notice though. so yes, personal preference wins on balance.

Where did you get them, might try them?

[Trevor]

I've just finished my first perusal of the plans in preparation for drawing up a shopping list. I have to say they are very clear and comprehensive - well done to all involved.

One thing I noticed is the lack of a hatch of any sort. This prompts two questions:

What to do for a switch?

Battery access for charging?

Taking the second question first, as a predominantly electric flyer (and cheapskate) I tend to use 2s or 3s LiPo batteries in my slopers. These have generally seen service in small electric models and, whilst their internal resistance has crept up a bit, are still perfectly fit for lower current applications. One consequence of this is that I do need to get at the battery (at least to get to the balance connector and ideally to remove it) for charging purposes. Access through the wing seat looks to be a bit awkward.

As for switches well, if you have easy access to the battery then simply disconnecting it rather negates the need for a switch so I tend not to fit them at all.

So, what to do on the Hurricane? The simplest approach is probably to just put an extension on the battery's balance lead and accept the compromise of in situ charging (I have to do this on some models anyway so make a point of doing it at the slopes in the open air, just in case!) This would still leave the issue of a switch and no access to the balance connector for battery checking once the wing has been fitted. On the other hand, something cunning like a bayonet fitting on the spinner to get straight to the battery would be neat. For those who like switches, how about turning it on with a twist of the spinner?

What does the panel think?

Trevor

[Callsign Tarnish]

Personally I think that leaving a lipo deep in a wooden structure and charging in situ is asking for trouble. I've not seen the plan but assume the wing is held on with a bolt? It's 30 secs work to remove so I'd stick with wing removal myself.

[Phil Cooke]

I agree with CT - I wouldn't rest easy knowing the model was stored/transported with a connected Lipo regardless of the type of switch used.

If you wish to use LiPo then some rework is required. Any hatch up front will compromise the stiffness and structure of the model unless the assembly is redrawn. Perfectly possible of course, but not the easiest route.

The model as drawn is suited to a 4 cell NiMH 'cube' which is guided all the way to the nose from the wing box in the square balsa tube - this tube forms part of the assembly and helps builders keep the nose straight and true. With some minor rework to formers F2 and F3 you could redesign the shape of the box to snugly fit your 2S lipo - you will still want to keep the battery as far forward as poss to avoid the need for ballast IMO.

Access from the wing bay is very quick and easy as CT suggests, just a single wing bolt and you are in. I would suggest this is the easiest solution without the major redesign needed to enable an access hatch up front.

If you DO redraw and go for the hatch route, please keep us informed of progress I would love to see the mods in progress!

[Phil Cooke]

As for switches, in the quest for scale appearance it's quite common to internally mount the switch and extend it to some external feature on the model like an aerial or probe or blister which can be pushed/pulled/lifted into position for flight. Alternatively a few of us use the neat little magnetic switch devises you can buy commercially which require no scale feature.

If neither of those are possible we just try to internally mount the switch so the very tip of the switch is just flush with the fuselage surface - so nothing protrudes - that way you get away with a simple 'spine' mount and no one is the wiser...

Other than the scale police during static judging of course - they see everything.

[Piers Bowlan]

I enlarged the square balsa tube on my A4 Skyhawk build to accept a three cell LiPo, I don't know if that is possible on the Hurricane? I felt that cutting a battery hatch in the A4 would weaken the structure too much, as my slopers tend to have a hard life. Removing the wing to charge the battery is less of a chore compared with glueing all the bits back together after one of my 'firm' landings!

Edited By Piers Bowlan on 29/04/2018 10:27:41

[Trevor]

Thanks for the responses chaps. Just to be clear, I’m certainly not seeking to convert anyone else to using LiPos. I mentioned it only to explain why battery access was perhaps a bit more important to me than to NiMh users.

Yes Phil, I’ll certainly let you know of any changes I actually make. However, it might be a while. Ideally I try not to build over the Summer but somehow I doubt I’ll be able to put off making a start until September, so who knows.

As for the Scale Police, I’m seriously considering taking up a suggestion to adopt a fantasy Reno Racing colour scheme (Red Bull perhaps?). That would at least get the ‘non-scale guilt’ out of the way in one fell swoop. Or would that get me drummed out of the PSSA?

Edited By Trevor on 29/04/2018 19:43:18