A place for Pushy Cat builders to hang out

[Colin Leighfield]

Thanks Doctor Ken,

Although it could have been the fire-water before the cocoa that caused the problem in the first place? Double vision! Hic!

Edited By Colin Leighfield on 16/12/2013 19:27:03

[Dave Miller]

I was more concerned about the untrimmed horn fixing screws - all that extra weight on the tail.

[Colin Leighfield]

Ken probably considers that they will function as a dynamic elevator balance and eliminate the risk of flutter. On the other hand, perhaps he didn't notice, as I didn't until you mentioned it Dave!

[ken anderson.]

fear not Dave--they've had a hair cut........

ken Anderson....ne...1 .....screws dept.

[Dave Miller]

Posted by ken anderson. on 16/12/2013 19:57:03:

fear not Dave--they've had a hair cut........

ken Anderson....ne...1 .....screws dept.

Good, otherwise I wouldn't have slept tonight worrying about them.

[Erfolg]

I am a few steps closer to finishing.

Like Colin I have had my moments today. Enough that i seriously considered giving up to another day. It is not that I am particularly superstitious, it is more to do with issues tend to be lack of mental agility and carelessness, due to tiredness.

The tiredness is just due to a 2.5 hour drive back from Cumbria and a poor nights sleep.

I have finished the linkages of, well I thought I had.

My tail servo installation is a little different to Kens. I suspect heavier and bulkier.

 

The wing servos are obviously differnt.

I positioned the control horn pivot holes over the hinge lines. It is only now that I have realised that some trimming may be beneficial.

I have completed the adjustment of the control surface movement as set per plan. This has taken me a little more effort than I thought. Again, I do not know what the rest of you do, in my case I like to have the servo set to 100% travel, with the clevis on the outer hole of the arm. This is my way of trying to get the most out of the available accuracy of the servos I use. I take a similar view with respect to the control horn (outer holes).

In the case of the tailplane servo I have had to cut the movement down to 80% and use the innermost hole.

I have also done my watts check, the watts I am pulling is lower than most being 21 amps, 246 watts @ 12v. This was my first cock up though, I apparently initially had not tightened the prop nut properly, as the watts and amps dropped as a strange noise was emitted from the motor. It was only when I got hold of the prop nut and promptly burnt my fingers, that it was confirmed there was an issue. I have bunt the motor out I thought, it was only on cooling did I find that the prop was only finger tight.

I have not as yet done a revs check and a proper check to confirm that the prop size used is correct. I know I should have done this earlier, but, but, I am tired.

With all the gear in place, the balance seems correct. For once this is a model with bags of space to both instal and move the equipment around.

 

I still need to attach the servo wire to the boom, do that rev check and a prop check. Again, I seem to remember that I have balanced the prop, though I will check,

Edited By Erfolg on 16/12/2013 20:48:41

Edited By Erfolg on 16/12/2013 20:51:13

Edited By Erfolg on 16/12/2013 20:52:52

[Erfolg]

It would be interesting to know which servos others are using, how they perform etc. Oh! and the cost.

To me there appears to be an amazing range of servos available, which differ greatly in purchase price. I have been wary of high priced (that is by my definition, over 50p) since I purchased some high priced Hitec servos that others raved about, stripped a gear in flight, which had me convinced I was being hit by repeated interference. It was only on landing did I discover the cause.

So feed back on experiences would be great!

[Colin Leighfield]

All of my bits are from HK, the servos are S90 1.8kg metal geared, but I haven't tested anything yet. I'm a few days away from trying anything out.

Tonight I've managed to get an hour in working on the top hatch and trimming the canopy to fit. I've cut the wing panels out and glued the front and rear sections together, but haven't started planing and sanding yet.

Don't weaken Erfolg, we've got until June and you're well on the way! I'm still messing about with the lightweight filler. Haven't a clue where I'd be without it. (Once a bodger, always a bodger).

[Erfolg]

Colin are they the 9g with the metal gears?

If so I am using those on my new wing on my trainer type model, they work well. I am not sure they are over the top on my model though, as I think it is where the servo arm etc can come in contact with the ground etc., that they come into there own. The picture is off the single servo wing, although the new is pretty much the same with two servos, although they are heavy.

[Colin Leighfield]

Bang on Erfolg, that's what they are. It sounds as if they'll be ok. I haven't decided yet whether to run with one or two servos to the ailerons, either way I think these servos will do.

[Dave Miller]

Out of interest what range of flying weight for my completed model should I be expecting?

[ken anderson.]

Dave-if you are using a 2200 lipo-I would say you are going to end up with a model in the 24 oz range......

ken Anderson ne...1........ 24 oz dept.

[Erfolg]

I have just been outside doing my last motor checks. Now I have a coffee, and made a few calcs.

The motor had a peek revs of 17,880, dropping to 16,000 after a few minutes. Using the latest mathematical techniques, that is a calculator I came to the conclusion that the max speed is 101mph and at say 15,000 revs/min, it could be 85mph. Assuming that the prop is 80% efficient the speeds would be nearer 80 and 68mph.

I use a little relationship of revs*pitch(in inches)/1056 =speed. The derived relationship is simplification of the all the elements that go into thinking the problem through.

I have also weighed the model, which is a rather portly 805 grams or 28 oz, when compared to Kens 24oz, when using a 2200 Lipo. I do not think that the additional weight is just the built up wing, nor the addition of 1/16" ply sides. It will be poor wood selection and over use of PVA and perhaps slightly heavier servos. In mitigation, the wing is slightly bigger in a area, having a extra 25mm width at the tips.

In a short time I will be of, to do some house renovation. Then back to finally fasten the servo lead onto the model.

[Dave Miller]

Your collective advice is again sort.

Having at last mastered the intricacies of the HK website I have today received a Tunigy D2826/6 2200kv motor to push this wee beast around, its maximum rating is given as 342 watts. The instructions also say it weighs 50g when in fact it tips the scales at 63g; which inspires confidence in the other numbers. Anyway, first questions will this tiny object give sufficient oomph and what size prop will suit the task best; I’m thinking 5x5”? I will be using a 2200mAh 3s LiPo battery.

The other point is that of speed controller, I have a Ripmax 40amp unit that emerged from a Wot4 foamy in the company of its engine when the rest of it remained in a grasping bush which I would like to use because it’s got the correct plugs on it. I also have a Turnigy AE-45A unit that seems to be more suitable for high revving motors, any idea which one will perform the best?

[GrahamC]

Dave....

"Will this object give sufficient oomph?" - Oh yes...That's basically the same motor as the one I am using. It will really shift. With a 6x4 prop you should be good for 90mph or so.... fast enough for you?

As for the speed controllers... give them a try. I'm not aware that there is a low KV limit on the WOT 4 ESC and I would think that it should work OK.

There is a video of one equipped with a 2200kv and 2200mah 3 cell here

[Erfolg]

Dave, you are using the same motor that I have used.

The data sheet says a 5*5 on a 3s. The discussion has indicated that many seem to be using a 6*4 on a 3s. It is the 6*4 that I have used to get the +200watts posted. I have used the 6" prop on the basis it should be more efficient than a 5", and this seems the preferred direction from users, but will be interested in the amps, revs etc., from anyone trying one (5".

Given that I pull well below 30 amps, the 40 amp ESC I am using, is well over the top.

Edited By Erfolg on 18/12/2013 16:35:57

Edited By Erfolg on 18/12/2013 16:43:02

[Colin Leighfield]

I know it might sound odd, but I'm kicking off with 7x3, I've got hold of two specially. I don't need 100 mph and as long as the current drain looks ok when I static test, I want to see how the larger diameter and finer pitch work out before I try anything else.

[Erfolg]

The face should be a closing bracket on my post, editing the post does not change it, as when re-posted, the same winking face is there.

[Dave Miller]

Thanks chaps, experimentation seems to be in order here, but first I have to build the thing.

I think the one in the film clip is a bit too pedestrian for me Graham.

[Erfolg]

I have been wondering how many Pushy Cats are under construction and have been built.

My spread sheet suggested that 5 were registered as part of the voting process. Yet there seems to be many more. From that i thought I would try and list those I can remember, so some may be omitted in this list, in no particular order, as they say on come flying at Greenacres.

1. Ken Anderson of department fame
2. Graham C
3. Colin Liefield
4. Richard Harris
5. Dave Miller
6. Richard Harris
7. Simon Burch
8. Tim von Model Markings
9. Bob Cotsford
10. IanR?
11. Woolsten Flyer
12. John
13. Depron Daz
14. Fred Clarke
15. Victor Saliba, will he be at Greenacres?
16. Andy Fox

That is at least 17, there could be more, who have I missed?

Who intends going to Greenacres? There could be a couple of squadrons!

[ken anderson.]

well-done erfolg--nice to see we have two Richard Harris's building PC's....don't forget baz......he will be upset..

ken Anderson ne...1 audit dept..

[Erfolg]

Ah well, could never count, just typed names as I could remember them, and a quick check, to see if I was half right

Seem not to remember Baz though

I am sure there must be more that I have forgotten and of course those girding their loins to commence in the New Year, not yet registering.

[Victor Saliba]

Wow, i am in the 15th position, I want to meet you all but unfortunately I don't have funds to come. Honestly I wish to and chat with you and share our experiences, I'm sure my friend Ken Anderson will introduce me to you.

[Colin Leighfield]

I certainly plan to be there, hopefully with a bit more confidence this time and weather suitable for making the most of the opportunity. It would be great if Victor could make it but clearly he's with us in spirit already!

If we can get all of the Pushy Cats up together we might even have enough to form a Balbo! That would put the willies up the Barnstormers! (Thinking about it, that would put the willies up me as well)!

[Erfolg]

A Balbo? What is it?