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Chilli Breeze from Sarik Plan, Electric Conversion.


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Afternoon folks.

The plan, wood and power system have arrived, and I will be cracking on with it very shortly, starting with the fuselage because that's where I always start, and I am a middle aged man and therefore fear change, And because an on line retailer provided me with trailing edge stock that curves like a boomerang, so I will have to replace it.

 

I am using a PROPDRIVE v2 3542 1000KV rated at 47 amps with a 60 amp speed controller and 4s 2200mah batteries. I haven't decided on the propeller yet but am thinking something like 12x5. As per Nigel R's recommendation the FWall will be placed about an inch further forward, and I think I will work out a bottom mounted hatch for the battery.

One thing that I am thinking about is changing the undercart to a trike - partly because I like the way they look and partly because I have an unreasonable fear of nosing over. ( I have no idea either )

Aileron servos will be fitted in each wing for simplicity and because I like nice short linkages.

 

That seems about it, so time to clear the board and assemble the SLEC fuselage jig before another banana takes shape in the workshop.  

 

 

Any suggestions, caveats or hoots of derisive laughter welcome.

 

 

Edited By Stuart Quinn-Harvie 1 on 11/02/2019 15:57:01

Edited By Stuart Quinn-Harvie 1 on 11/02/2019 15:57:39

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You'll struggle to get it to nose over. It sits low. It is long. The wheels are quite forward. And are also set wide. Ground handling is excellent.

12x5 is (in my opinion) way too much diameter for 4S, and not enough pitch and I think you will find it draws a monster current from that 1000kv motor - I'd suggest 10x6 or 10x7 and go from there.

As a comparison, I just finished an RM Aerobat, which is somewhat sleek although not quite as much so as the Chilli, it is just shy of 3-1/2lb, has a 10x6 on a 3536-910kv motor with 4S 2200mAh lipo, my wattmeter shows 450W and I get an 8 minute flight.

Might be worth planning ahead for motor mounting & cowl arrangement.

My larger Chilli, uses a 2-1/2" spinner. This means the nose ring can be (and indeed has been) opened up enough to get the motor in through the front. Four small notches provide just enough space to get the screwdriver at the mounting screws. Not sure if that approach would still work on the smaller size - what is the spinner, 2"? Going to be tight!

Watching with interest.

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A slightly delayed start due to life the universe and everything, but tonight I got the SLEC jig together ( one of those jobs I had been meaning to get around to ) cut the root and tip templates and sandwiched some balsa together. I've not used the sandwich method before so decided to start with that - having a set of wing ribs always cheers me up.

I've been playing with a plan built Cardinal as well ( I have always had a terrible habit of doing more than one project at a time ) and that is up to the installation and covering stage.

I'll put up spme pictures when I have something to show

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I've actually started. I cut the ribs ( and decided I REALLY dislike the sandwich method - although alighning them all to the trailing edge may not have been the best ides - perhaps aligning them equally to the leading and trailing edges would be better. Either way it' done now but I am going to do it differently next time, just to be sure.

the plan calls for the TE and LE to be supported first, then the ribs, THEN the spars, but being an Olde Farte with some Fixed Ideas, I've decided to put the spars in first aligned to the TE then add the LE. I am not sure which way is better, but so far the wing is nice and true, so I am happy so far.

Having paid seventeen quid for the plan ( I think this is the first time I have built from a plan that wasn't free in a magazine, or from Outerzone, and only the third or fourth plan only build I have ever done) it felt odd chopping it up, but there we go, I suppose. Rather than covering it with cling film, I use double wide sticky tape and that keeps everything glue free and doesn't crumple or get in the way as much.

It's not the best build by a long way, but it's a start - and I am enjoying it.

img_20190217_223023.jpg

img_20190217_223033.jpg

img_20190219_233851.jpg

img_20190219_233905.jpg

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I can't stand the sandwich method either. All the edges come out at an angle and need dressing afterward, and I always ended up with lumps and flats shouldn't be there.

I like printed templates much better. They seem to take about the same amount of time to make a rib set. And it is more accurate when done.

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Hi Nigel and Piers: Indeed - I think I'll be investing in some kind of rib/drawing software in future.

After some fettling I am here now - about two thirds of the way through the wing panels. In a spectacular case of having the instructions printed out next to me and ignoring them completely I put the root ribs on because of course I did. I really should have thought about it more but I decided at the time that I would just cut the ribs away where the dihedral braces would go, so that's what I am going to do. It'll be fine, I just shouldn't have been watching TV and building at the same time. My building will never be to the standards that some of the folks on here exhibit but it normally is good enough to get a well behaving aeroplane out of things. img_20190226_114335.jpg

Having gone back to look at the instructions again, I see that they mention spar webs - although none are shown on the plan - does anyone have any advice here? I am kind of leaning toward putting them in out of a belt and braces attitude.

Servo mounts will go on very soon - possibly this evening and I hope to start the fuselage tomorrow, using a jig for the first time.

Speaking of the fuselage, I will, as per Nigel's recommendation be moving the firewall forward and I am contemplating ways to lighten the fus a bit too. I was thinking balsa rather than ply doublers crossgrained to the sides, for a start, and 9g metal geared servos in the tail for the ele and rudder. ( just for ease of maintenance, if nothing else. )

And I need to start thinking about the battery hatch. Stuart Marsden's electric conversion thread is being very helpful, btw.

Undercart will be mounted on the fuselage rather than the wings so I will beef up the mounting area too.

Right, back to work.

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Yes, definitely use spar webs. Weight, almost nothing, increased resistance to warp and bending, lots. It's not belt and braces, the webs simply complete the D box structure, without them it is only part formed.

I'd personally never use smaller than a HS225 on the tail surfaces on something this size, and HS81 for ailerons. Preferably in metal gear flavours. 9g are ok for park flyers that weigh 1/2lb.

Other opinions are available.

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I reckon a ply doubler will be even more important if you mount the u/c on the fuselage. Maybe reduce the height of the ply though, perhaps just draw a straight line from F1 to the end behind the wing - a long thin tapered triangle shaped doubler which would almost halve the ply and glue needed. Of course extend it to the new F1 if you move F1 forward. Would be sufficient for electric. A ply doubler usually means a plane stays resonably straight, intact and repairable after a crash or hard landing. Worth fitting.

Consider a torque rod u/c as used on many of Peter Millers recent models also Boddington designs etc.etc.

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Well spotted kc, fuselage mounted U/C definitely favours a ply doubler, and I'd agree with tapering it. I'd draw a straight line from top of the firewall to a point about 1" above the wing TE though, just to give a bit of meat across the wing saddle.

Torque rod U/Cs are great shout too. They have a lot more "give" than a plate aluminium gear, and lighter too. Quite simple to bend up. I try to pattern the leg like a 3:4:5 triangle, that is, make the leg itself 5", bend it so that it drops 3" and projects outward 4". The exact dimensions will just need scaling appropriately, but this is kind of about Chilli size:

20-size-torque-uc.jpg

You just need a 1/8" ply plate on the fuselage underside. Several bits of 1/8" birch ply or 1/8" spruce go above the plate and hold the torque arms in place.

On a low winger I would stick the U/C on the wing though. You can get the wheels further apart and the whole thing is thus a bit more stable.

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If you angle the slots that take the vertical part the wire can be flat and not 'handed'. Angling is done so the wheels come under the LE or whatever suits the design. The flat wire parts are therefore useful for other models too - they outlast the model normally and also make the old model without u/c easier to store.

The slots in the ply need to be staggered by the thickness of the wire to allow the u/c legs to fit alongside each other. I always cut the slots in 1/8 birch ply slightly undersize and cover the slot with a slightly smaller piece of ply- total thickness is then 1/4. Then at final stage run an exact size drill through which gives a slop free fit. Easier than trying to drill an angled hole through 1/4 ply!

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  • 2 weeks later...

Afternoon folks, as you will no doubt have noticed my building speed rivals a glacier's progress, but progress there has been.

First of all thanks for the UC advice, chaps.  

The wings are together, waiting to be glassed at the joint, and servo installation, the tail and control surfaces cut out and, in the case of the tailplane, assembled.

The big progress is the fuselage. I never, ever seem to get a fuselage right. I used a SLEC jig for the first time on this one, and at least all the datum points line up. ( Please ignore the scruffy cut outs - I am quite ashamed of some of the build standard on this but it shouldn't affect the flying qualities aside from a little extra weight)

Seriously, cutting identical fuselage sides seems completely beyond me, but of course now I have had a brainwave: I should tack glue the balsa sheets together then use a suitably supported knife to cut them both at the same time...( I have a foam board cutter that would do this job well) Oh well, if it turns out too bad I can always make another - as I say though, the datum points are all correct and the tail, wings and thrustlines will all be correct ( if I get it right, that is, they are all ok at the moment. )

 

img_20190309_191213.jpg

 

Oh yeah, my favourite mug shot:

img_20190309_191251.jpg

 

Stack shot : ( Doesn't everyone do this? )

img_20190309_215312.jpg

 

Being me, I obviously drilled the firewall holes after installing the firewall, because I am an idiot. That said, I can attest that the thing is in there to stay, and it's all nice and smooth ( with prescribed right thrust ) now thanks to messrs Dremel and Permagrit.

I have decided to put the battery hatch in the top near the nose,and here you see the spruce longeron doublers ready to take the hatch ( Which I will figure out in my somewhat Doctor Who - like fashion of "what's around and how can I make it work?" ) The doublers for the torsion leg UC will be going in tonight.

 

53869298_2303470416642700_8769142080950763520_n.jpg

 

 

As you can see I went with a full doubler as per plan - I decided that if the battery hatch is going in the nose it should be as tough as possible.

I am not a light builder, I am afraid.

 

53671936_2303470379976037_2829633065737781248_n.jpg

I have been planning the radio installation and reckon that the ESC will go under the battery shelf ( just behind the FW ) and the two tail servos in the location suggested on the plan.

The colour scheme will mimic, ( gently) the white and red of the late sixties Lotus racing cars.

Also you may have noticed a Cardinal fuselage next to the Chilli - that's a parallel build and will be a "puttering around to relax" model for after Chilli sessions.

Finally, does anyone know anything about the Chilli sauce? I saw it in a couple of old ( around 2003 ish ) RCM7E mags a while ago and wondered if it was ever published as a plan, or if anyone knew anything about it. ( There were pictures, but absolutely nothing in the collumns )

 

Anyway, cheers folks. More as it happens.

 

Edited By Stuart Quinn-Harvie 1 on 11/03/2019 17:26:31

Edited By Stuart Quinn-Harvie 1 on 11/03/2019 17:27:13

Edited By Stuart Quinn-Harvie 1 on 11/03/2019 17:30:56

Edited By Stuart Quinn-Harvie 1 on 11/03/2019 17:38:39

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  • 3 weeks later...

Progress! I am at the point where the radio is going to HAVE to go in. ( It's my least favourite part of any build, So I am doing two things: Thinking about another build and gritting my teeth, installation of fuselage servos begins soon. )

So yes, empennage fitted, with the aid ( again ) of the SLEC jig - checking the datums very carefully against the jig and the tail surfaces. ( The tail plane was supported either side by blocks and the whole lot stuck in the jig. )

img_20190316_003103.jpg

( you can't see the levelling blocks, they are under the tp ) I didn't build a fin post, as per plan, ( Although it would have helped with getting everything straight, but there you go) but epoxied a fin post and subsequently the fin to the tail and the fin support along with reinforcement - it will hold. And it's straight. Tail alignment was checked with measurements from tail tips to nose centreline, as well as checking against the gridmarks on the jig with a set square.

I sheeted the top of the fus and the rear bottom also using the jig just in case anything pulled out of line whilst drying.

Then I made a bit of a mistake: I cut the battery hatch but, er, yes, I made both cuts vertical at 90 degrees to the thrustline, which means of course that getting the thing on and off is a proper pain, so that's been fixed: it's now at 45 degrees at the rear.

There is a ply tongue in front and there will be magnets holding down the rear.

 

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Oh and the aileron servos are in and the wing joint glassed.

Next is installing the UC mounts ( for a torsion rod setup ) and the battery shelf, getting the tail servos in and mounting the motor and ESC.

Edited By Stuart Quinn-Harvie 1 on 28/03/2019 11:06:57

Edited By Stuart Quinn-Harvie 1 on 28/03/2019 11:07:36

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Thanks Nigel. Oh yes I am a total Jig convert - I wish I'd had one about 40 years ago!

I put in the undercart doublers/mounts yesterday and modded the hatch so that you can get it on and off without gouging bits out of it, and installed the battery shelf so I guess it's time to start covering.

Jobs left:

 

Covering

Hinging control surfaces ( film hinges )

Mounting motor/ESC/RX

Making cowl

bending and mounting UC

Setting up controls.

I wonder if I can get it done by next Friday? ( Fridays are good at our patch - just enough folks to be sociable but not enough to pack the skies with models. )

 

Edited By Stuart Quinn-Harvie 1 on 29/03/2019 18:45:42

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