Chilli Breeze & Chilli Wind plans (was RCME June 1994)

[kc]

Jon, I still have the article available so it's no problem to let you have a copy. You should be able to send me a PM by clicking "Message Member " -it's not dependant on having a public profile. So send me a PM with a normal e-mail address and i will send the copy to you.

[Jonathan M]

PM sent.

How stupid of me! Of course the 'Message Member' option! Maybe its time to have a word with my GP... and get a couple of models built before its all too late....

[kc]

That's OK Jon, first part of the article has been sent

[Jonathan M]

Cheers kc, all three parts have come through fine.

Reading the article now makes me wonder now if my intended power-plant, a new OS35AX, might be a tad too powerful for this 48" version (designed for older 25 to 36 engines)?

The Chilli Wind is 57.5" (40 to 50 engines) which is bigger than I'm looking for, so I wonder if enlarging the Breeze plan by say 10% to 53" span would make for a better fit?

The wing will be made for me in foam to root and tip sections, so it would just be a matter of enlarging the formers on the copier and re-drawing the fuselage outlines etc on lining-paper.

[Nigel R]

Worry not, the 35AX will be a perfect match as is. The AX is no more powerful than theengines of the mid 90s.

[will -0]

Hi

I have an ASP32 powered one which is fine. It's certainly not overpowered but not underpowered either. I think the 35 AX would be an excellent choice.

FWIW I ended up adding tail ballast to mine

[will -0]

.. double post

Edited By will -0 on 24/06/2019 10:01:55

[Jonathan M]

Thanks chaps.

[kc]

The first paragraph of the article says the model was designed for the powerful 28 to 36 twostrokes, or the lighter weight .40 such as 40FP. So the AX35 seems perfectly suited. Note what it says about shortening the nose for the .40 engines though

[Jonathan M]

Quite right kc, I glossed over that on first reading (it's one of those days!).

He fitted standards in the prototype but reckoned minis would do fine. I'm inclined towards 85MG servos all round, with separate servo wells in each wing rather than a single central one for ailerons - unless there's a good aerodynamic reason to keep all the weight on the centre-line?

[kc]

In the same 1994 issue Futaba mini servos were advertised for 29.99 pounds each while standard 148 were 11.99 so thats probably the main reason for using 1 servo for ailerons and standard servos all round. Multiply by inflation and they were expensive - equivalent today at perhaps 120 pounds for 1 mini servo!   Imagine if it cost 600 pounds for a set of 5 minis now......  

Edited By kc on 24/06/2019 11:25:31

[Nigel R]

My take on servos, as a minimum, HS225 metal gear on elevator and rudder, HS85 metal gear on each aileron. It's too much model for a 20g (ish) servo on elevator/rudder. Other opinions are available - depends on your risk tolerance. I like crashes to involve my own lack of piloting skills, not kit failure!

I would also consider sticking with torque rods. Not because of skimping on the number of servos to purchase, simply that I find them less work than hatches and outboard servos. You can still use two 85s mounted in the centre section of the wing, or use a single 225. The fuselage makes good use of the canopy area to tuck the elevator / rudder servos away in, so it is not too cramped. Again, other opinions are available.

As kc points out, micro servos were very expensive at that point (and not particularly robust if I remember right).

will-o makes a good point about the CG, mine had the RX battery (standard 4 cell AA in those days) located in a box immediately behind the trailing edge. It was a squeeze to get a flat pack in that spot as the control runs were very close by, but worth it to avoid ballast.

[will -0]

On the servo thing:

Torque rods don't spoil the line of the wing.

The area for installation is not overly generous. I fitted mine out as per the plan with full size servos. I had to use a 2/3aa flat pack alongside the rear servo as there was not room for anything else and I was trying to get it as far back as possible. Mini servos should give you more space to play with, but check it carefully!

Fuel tank: I found a 4 oz slec tank fitted just right. (I think it was the 4 - I'm not getting it out to check as it's a PITA to fit as there is, again no room to spare)

This does not give hugely long run times (well not by my standards anyway) I think I have my timer set at 6 minutes - would probably go a tad longer but I also don't like to run out of fuel with this type of model.

[kc]

One of the advantages of servos out in the wing in such a compact model is there is no chance of aileron torque rods clashing with the other servos. A big plus and worth the effort of hacking servo wire holes in a foam wing.

[Nigel R]

It's not massive, but even standards fit. Down to HS225s and the clearance is there. There's a fair bit of canopy to stuff the elevator & rudder servos up into.

As usual, YMMV - which is half the fun of rolling your own

[Jonathan M]

Fuel tank - The plans specify 6oz and the SLEC version (red) looks fine as it has a 47mm sq cross-section which will fit the 50mm sq cutout in F2.

Servos - Yes, of course 225s would be better for rudder and elevator. Re wing-mounted or central servo(s), I can see good arguments for both. Torque-rods would be cleaner, but if space is tight (esp for RX battery) then wing-wells would free up a bit of wriggle-room in the fuselage.

Wheels - Mike Delacole specifies smallest possible, 1-1/2" diam but whether these will handle our grass patch will have to be seen.

UC - Built-up wing shows hardwood bearers built into the forward rib-structure - each has a long piece of 1/2"x3/4" section with an additional piece to make it deeper at the inboard end where the torque-stub fits in (i.e. a L with a very long foot). Question is whether a similar arrangement can be let into my foam wings - or would they need an additional 'brace' running fore-and-aft for a more secure anchorage in the foam?

[Nigel R]

U/C - foam needs "surface area" in contact with your hard points. I'd go 1/4" ply plate, 1" wide, 5" or 6" long, let in to the underside. On the top, let in a 1-1/2" length of the same stuff. Make sure the torque rod end goes firmly into (but not quite through) the topside piece.

[will -0]

Yeah red Slec tank rings a bell. Not sure other brands will fit.

U/C - have small wheels but have had to repair the undercrackers as the torque end split and broke free from the beam (built up wing).

Good luck with the foam wing, hope it's not too heavy!

[Bob Cotsford]

A tip my mate Dave gave me years ago:-

Take one broom stave and cut off two lengths equal to the depth of the wing. Round of the end of the remaining broom stave and SWMBO will never notice the missing length.

Now bore a hole through the wing of a diameter to match the stave, centre this on Nigel's ply plates at the point where the vertical leg of the torque rod goes through, the plates may need to be 1 1/2" or so wide to accomodate this. Drill the stave centrally for the torque rod, give it a good coat of PVA, Gorilla Glue or whatever and slide it through the wing to span the upper and lower plates.

Sand flush with the wing surface when dry and you will now have a torque rod undercarriage mount that will outlast the rest of the model. If the Missus has hidden the broom any similar dowel 1/2 - 1 1/2" diameter will do depending on the size of model.

Edited By Bob Cotsford on 24/06/2019 18:30:34

Edited By Bob Cotsford on 24/06/2019 18:31:57

[kc]

Bob, if I cut the end off SWMBO's broomstick will she still be able to fly with it?

[Bob Cotsford]

Posted by kc on 24/06/2019 19:27:45:

Bob, if I cut the end off SWMBO's broomstick will she still be able to fly with it?

She may need to adjust her C of G to compensate kc, Weightwatchers could probably suggest an appropriate spell

[Jonathan M]

As I'm currently witch-less I've decided to forego shortening my own broom, but have concocted a variation using 1" square softwood. Also going to fit 2" wheels as the 1.5" version will struggle on our patch.

I never initially received the plans from Sarik so I called them a week after ordering online. A despatch email duly came through, then a couple of days later two separate envelopes arrived! So if anyone fancies building a CB and wants my second set just PM me your address.

[kc]

Nice reply Bob. Fortunately CG is well within limits. I will get a spell cast on me if SWMBO reads this!

Jon there is a theory that it's lighter & stronger if the 2 vertical blocks etc meet in the middle or are common. Possibly needs u/c legs to be longer in the horizontal plane but worth considering. But it means the vertical part is well within the fibrglass bandage and if damage does occur it's hidden in the fuselage so no visible scar.

[Jonathan M]

Saving the nation's broom-handles for their proper flight-modes...

...and developing kc's extremely sensible theory, how about just using L-shaped ply plates on the underside only, meeting in the middle as before, and with each fat foot mostly under the glassed bandage?

This would spread the twisting forces under the now horizontal feet across a wide enough area of ply over fully intact foam. Simpler to construct, less intrusive (nothing on top of the wing or going through the foam interior), and simpler to repair if needed. This extends the length of the main torque-arm only very slightly so shouldn't make much difference to the springiness of the UC, and total weight surely no more than the through-wing variants.

PS Sketch not to scale.

PPS Spare plan now posted to first respondent by PM... for an electric version.

Edited By Jonathan M on 26/06/2019 08:33:16

[kc]

Actually what I was trying to describe was just having the vertical supports joining each other in the centre. However what you have now drawn seems very good instead.  But wouldn't it be useful to have the plate in one piece to form a dihedral brace too. then only 1 double groove u/c clamp could be used.  ( allowing for dihedral in some way)   It's debateable whether the ply needs to extend out as far as the wheel but only needs to go just beyond the u/c clamp to be just as effective. Extra width of the ply plate may be better than length.

I also suggest that the clamps are most effective if they are almost at the end of the wire and the others as near as possible to the bend.

 

Edited By kc on 26/06/2019 09:05:57