A place for Pushy Cat builders to hang out

[Erfolg]

Hi John, me to, not a lot done in recent days.

Yesterday I went to Webbies and purchased some film, for the wing and also a wing refurbishment/modification on an other model in service. Now at home and checking my materials stock, I find I have a good quantity of 1/32 sheet plywood, a massive 1/8 sheet, yet apparently no 1/16 plywood sheet. Just as bad, I have also found that I have a lot of spruce spars, when I thought i had only large section spars.

I must say that I was pleasantly surprised at the cost of the film, which I guess is Chinese rather than Solafilm. If it is the self same stuff I used on my Clean Sweep, it is good stuff, using Solafilm as the benchmark.

Webbies is a long trip for me, yet going through the door is akin to stepping into Aladdin's cave. The staff are certainly help full and friendly, and that is before Fred is encountered, always wrapping mail order goodies. Over his head hang so many of the models he has made. Yes, Fred is a modeller, from the time when modellers really knew how to build. Always helpful, a true gentleman, it is worth going to Webbies just to have a chat with him.

Yet back home, I have done nothing, annoyed that i do not have any 1/16" ply apparently, not that I am prone to repeat myself, or whine about my own incompetence.

Now why will my wife not allow me to hang my models from the ceiling as in Webbies, whole squadrons of them, from Fred's FF models right through to the latest model trade offerings. Ah, yes, my models are not as pretty or pristine.

[ken anderson.]

reporting that ne....1's PC no4....had its maiden flight today.......who's next to defy gravity.....

ken Anderson ne..1......tech dept....

[GrahamC]

Congratulaltions.... its a bit too cold for me at present! Decided it was a shed day today!

[brfc7]

No more done here since I shaped the wings, combination of child minding and not being very well Don't think I can be arsed tonight either.

I will defo get the wings glued together and the holes sorted ready for the 2 servos and cut ailerons out sometime this week.

baz

[John Privett]

Well done Ken! Looks like sunshine in the pic too...

Mine's had 11 flights now and I've even bought two more batteries for it.

[Andy Fox]

Here's my PC I built a while back ... sadly motor has died, so looking for a replacement. Was using an inrunner before - What are you guys using?

[ken anderson.]

this is what is in mine andy.............an outrunner.......that is a nice model you have there....

 

ken Anderson ne..1 .......engine room/PC dept.

Edited By ken anderson. on 26/11/2013 16:53:14

[Erfolg]

Andy

Yet another really good looking model.

Will it be at Greenacres?

[John Privett]

Posted by Andy Fox on 26/11/2013 15:23:53:

Was using an inrunner before - What are you guys using?

That looks great Andy. Are the wings painted? Or is it film/trim, or what?

As for motors, as I previously mentioned (many pages back!) I use a 2200kv "WASP" B2835 inrunner - initially with a 5.2x5.2 prop, but I replaced that with a 6x4 for easier launching - just a gentle underarm 'lob' and off she goes!

With Ken's 1120kv motor running at about half the speed of mine he'll be using a somewhat bigger prop than mine!

Edited By John Privett on 27/11/2013 00:12:15

[brfc7]

Ken and I use APC 8x6E props on the BC-2836/7 1120kv motors = 180 watts / 17 amps

The model on average = all up weight is 25oz so say 1.5lbs = 120 watts per Lb

baz

[fred clarke]

A few thoughts on power/weight etc

I first tried elec way, way back when very little kit, and even less information (the internet was 15 years away) was available. My first attempt, an MFA kit (can't remember name but has been in Fly Electric column a few months ago), was uninspiring; a successful flight was if I was able to maintain launch height. All was solved, however, by fitting a PAW 2.5 diesel! My first really successful electric was a Simplex (post war free flight) powered by a Graupner Speed 600, 7 cell nicad, 3:1 gearbox and a massive prop.

Things improved, slowly, as more and more information filtered out and kit moved from brushed to brushless via cobalt motors; 'speed' control moved from a servo operated micro-switch, via other electronic gizzmos, to esc etc etc etc.

The one thing that remained with me, however, was the belief that you can never (well, nearly never) have too much power. After all, that is what the throttle is for. So, especially now that costs have fallen dramatically, I will have more power than quoted for a plan/kit or whatever. My PC works out at around 160 w/lb flat out. However, once happily in the initial climb, throttle back (typically to about 2/3 throttle) and away.

Not suggesting this is the only way but it works for me.

[Erfolg]

I have restarted work on my PC, being distracted by the need for a new wing for Miss Michelle trainer design, now renamed Dr. Michelle, to the upgraded and hopefully true flying wing.

The Dr. Mitch, wing was an interesting exercise in its own right, being a conversion from a Rudder controlled wing to a tagged on aileron wing via a central servo. I have converted it two a two servo aileron wing, using inset strip ailerons. It perhaps should have been a blog, on how I have done it, hopefully with feed back on how others have done the same thing. Any way pleased with the build, it now awaits to see if it flies true.

Now I am at the covering stage for the wings, I am looking for feed back on the approach that other PC builders have taken. Principally as I see the booms as a nuisance. Are they covered first, how about the tailplane assembly?

As I have not as yet mounted the servos, I will do this in preparation, for the all important feed back/advice.

I am not clear how many of the PC's are new build and how many intended at this point going to Greenacres?

[Erfolg]

With the high wind and constant drizzle here in the NW, I have had some time to work on the PC.

Although a bitty process I have installed the Servos into the wing.

Before starting the covering there is the little issue of the elevator servo. I had intended fitting a 5g servo for this function, I think every one has fitted at least a 9g servo. So a little feed back on these would be really appreciated.

I had considered 5g servos for the wing. In fact I was under the impression that they generated something like 2.5 kg toque, though on checking I see that the value is actually 1.5 kg. I have even gone as far to dig out my old manuals to try and find the performance on the old Linwood, Waltron and Micron servos (the latter two types being self assembly kits, no CE marks or equivalent on those old puppies),for comparative purposes, alas I do not seem to have any data.

Stumped at the moment on the best compromise

[fred clarke]

Erfolg

My thoughts on the points you have raised in your last 2 messages.

Covering - I used solarfilm throughout. Cover the bits (fuselage, booms, wing and tailplane) before gluing together. Just ensure you end up with wood to wood joins by stripping off any film that gets in the way.

Servos - I used 2 * 9g servos, simply because they are what I had, both mounted simply using silicon. I now use the 9g metal versions (eg 14g) on my newer aircraft simply because I can't be bothered to get too wound up by the odd few grams weight and the mg ones seem to have less play. I cannot see 5g, 1.5 kg servo causing problems especially if you have 2 of them on ailerons. After all the standard PC will turn the scales at something around 800g. As far as the elevator goes, try this. Build aircraft as complete as possible excluding elevator servo. Rig out in flying condition (eg prop, battery etc etc). Balance on a straight edge and then see how little force is needed at the elevator to get the aircraft to pitch. If you want you could even tack the servo in place with a bit of tape. This is how I eventually sorted out my PC landing gear position.

Hope this helps.

[brfc7]

Got a little bit done today.

Firstly I glued the wing tips on and then shaped them to the wing profile

Then I glued the 2 wing halves together

While I was on gluing I put some triangle balsa on the underside of the tail plane, both sides. To finish the day off I had a dry fit of everything so far.

Servo holes and ailerons to cut out next

baz

[Erfolg]

I have done a little today on the PC. I was balancing the needs of 3 projects with one and other, as they are all near to completion. You know, that bitty, fiddley stage.

On the PC I have undertaken some slight mods to the internals of the forward part of the body, ensuring that a 2200 Lipo can be inserted, moved about to obtain a non ballasted CG and be removable.

The other issue remains the elevator issue. I am now painfully aware of my lack of planning with respect to the elevator servo. I needed to have inserted a servo extension lead into the wing whilst building it. So I will have to retrospectively remove some of the outer skin, so that the cable can be fed through a wing rib, then put in a patch, to reinstate the skin.

All these things would have been done for me if I had just followed the plan and method of construction, that is the down side to customising, all the mistakes, belong to you, no one else to blame.

Seems BRfC7 will also finish before me, so the next question is, who will be 3rd?

[brfc7]

Posted by Erfolg on 02/12/2013 00:12:15:

Seems BRfC7 will also finish before me, so the next question is, who will be 3rd?

Long way to go yet, I'm sure Graham must be finished by now. I'll be lucky if mine is ready to cover before January.

Baz

Edited By brfc7 on 02/12/2013 08:28:11

[Erfolg]

brfc7

Looks pretty near finished to me. Seems to be going well.

Now with respect to my own model. all my anguish and angst with respect to which sized servo to use was pretty much in vain, wasted energy. Having assembled the model again (with Lipo), it would appear to be nose heavy, so the weight of a 9g, is not an issue, useful, in a sort of way.

So I have started the installation process of a servo extension lead. I had initially thought of using a servo with a extra long lead having hard wired an extension lead to a 9g servo for another model. Experience has taught me that with small servos, they often need to be changed, due to servo, gear train, damage, In my case, from anything from landing, through to careless storage/handling. Yet it really gripes with me, servo leads, plugs, all out in the open for all to see. Yet I do remember my farther's advice with respect to most British Railways steam locomotives, making them pretty, tucking everything away out of site, from steam ejectors/lifts, to having wheel guards made for difficult maintenance, where as most European engines had everything on display, a mass of pipes, uncovered wheels, although dam ugly in my view, yet far more serviceable.

[John Privett]

Mine just has the standard 9g servo plugging into an extension lead taped to the tail-boom. The lead runs along the trailing edge of the wing and then back along the fusleage for a couple of cms to enter via the motor cooling aperture. OK, it doesn't look pretty, but you certainly don't see it once it's in the air, and you don't really notice it on the ground either!

[Erfolg]

Oh dear, I must have been really tired last night, commas where there should be none, similar sounding words being used (site for sight) etc. I do not know about others, I often find that I believe I have hit a letter key, only to find that the letter is not on the screen. Perhaps if I read what I have typed, it would help, just as I did when working.

Yes, John, I agree that in terms of functionality, a few wires etc. here and there do not matter a jot. It is something inside me, that baulks at things in the open. I have come to value ease of maintenance, yet I still like things covered up, with easy access for maintenance.

Given my wing is hollow, it seems a good place to run my servo wires.

I can see that others servo mountings are extremely well designed and engineered. I am not however convinced that I can achieve the same results if I just copy, I do not seem to be able to cut small sizes of ply, with the precision of others, without it being as weak as knitting needles, looking strong, yet in reality, not so.

[Erfolg]

I have just finished inserting a servo lead for the elevator.

To do this I had to create a hole in for the lead. Which is easy enough, although if done earlier the compensation for the penetration would have been inside. This would have been marginally better aerodynamically, a lot easier to cover.

To get the lead to the existing aperture for the servo lead out, I had to remove some of the skin. This can be seen as a triangular insert, surrounded by some PVA.

It is now onward and forward to the elevator servo mounting, then covering.

[brfc7]

Got a bit more done today

First off was to mark up the wing for the ailerons and cut them out (Probs a bit easier to do this before joining the 2 wing halves together)

Next was to measure and mark up on top of the wing where I wanted the aileron servos to go.

And cut the holes

What I decided to do is to install the aileron servos level with the top of the wing and have about 4mm of servo below the bottom of the wing but won't come in to contact with the ground due to the tail booms. Then I decided to glue some 1/8 sheet squares on the top of wing, 1 to neaten up the top and 2 to aid gluing the servos in.

baz

Edited By brfc7 on 03/12/2013 22:58:24

[Colin Leighfield]

I'm still enjoying watching these. I ordered the motor and ESC a fortnight ago, so hopefully they'll be here soon. Also I've made some alrerations to the plan to make it look a bit different. When the bits arrive, I'll make a start.

[Erfolg]

Brfc7, it will be interesting to hear of your experiences in practise with respect to the aileron linkage being beneath the wing.

My own experiences with other aircraft, seem to support the notion that a substantial gap is required to prevent grass divots wiping out the gear train of the servo.

Or maybe your landing strip is more akin to a cricket pitch, whereas my own clubs are in one case rough pasture, in the other a lot in common with Pennine Chain in miniature.

Now Colin, no more excuses, start cutting those first pieces of balsa. I am intrigued as to your intended modifications and the reasoning behind the proposed changes.

As for me, I cut the elevator to size last night. This morning I found that the elves had been during the night and cut it about 50mm short. Now if I could only harness them to do useful work. Rumpelstilzchen where are you, and get back to work!

[ken anderson.]

erfolg-that's the top of baz's wing with the servo arms sticking through in the photo.....so his rods etc will be on top......

ken Anderson ne...1 ......rods on top dept.