A place for Pushy Cat builders to hang out

[Erfolg]

RH, seems to be a lack of judgement. Many of us enjoy building and flying models that are not the run of the mill. After I have finished Pushy Cat, or my Super Pussy  as I will be calling it.now I will press you for the details

Graham, I see no need for tow in, there is a RC posting that suggests it is beneficial,. I wondered why it would be needed, although I have seen it on engines on twins, although I thought they go for tow-out, So I asked the question.

Edited By Erfolg on 20/10/2013 23:16:30

[GrahamC]

No problem Erfolg... I just wasn't sure that my build was accurate enough to worry about toe in and toe out!

Some useful information for potential Pushy Cat builders:

Due to my own plan woes, I have this morning spoken to Q&EFI. They tell me that they have plenty of copies of the back issue in question, and they are available in the UK for £6.15 including P&P [Thats what I think it cost!]

So If you want to join in with the build. Q&EFI are on +44(0)1684 588599 and the issue you need is January 2005.

[IanR]

Now he tells me! I ordered the rotten plan, yesterday. Oh well, I'm not to 4 quid.

Ian

PS   4-Max have a listing for a powertrain for the Pushy Cat.  It includes a 2700kV motor, a 4.75" x 4.75" prop and a 3S 2200 lipo.http://www.4-max.co.uk/customermodels56.htm

Wouldn't this make it a bit of a screamer - noise wise that is?

Edited By IanR on 21/10/2013 12:20:13

Edited By IanR on 21/10/2013 12:21:15

[GrahamC]

Ian... I think you will find that that is a legacy bit of the 4max site, and you can't actually buy that motor from them anymore. I think iyiu are right. It might make. A racket!

If you follow the link from the page, it goes to a massive motor! 

Edited By GrahamC on 21/10/2013 14:49:06

[Erfolg]

I believe from some of the postings that a few have built Pushy Cats previously.

I also know that the original was using Nicads, which eventually leads me to my question:

• What size lipo is typically being used, I am guessing that it is a 3s, what size?

 

PS Looking at the drawing, I do not think it is in any way necessary to have a repo of the pub. article. It is a simple build.

Probably the considered feed back from contributors such a KC (having built and flown at least one) will be just as useful.

Edited By Erfolg on 21/10/2013 16:43:54

[ken anderson.]

hello erfolg....all the pushycats(3) I've built and flown have used 2200 /3s/20c..the one above(no2)...shows the lay out I use....with the lipo in the front-not as shown on the plan...

ken Anderson ne.1 .......no 2 dept.

[Erfolg]

I intend or intended to use 5g or perhaps 9g servos.

Looking at the drawing the servos are not specified (as far as I can see), although the outline appears to be very small. So the question (always asking questions) what are the servo sizes etc. that builders have used, then the next question were they up to the job?

[GrahamC]

I used 9g sized servo for the elevator. For this build I'll be going metal gear on that one. For the torque rod servo, I used a mini servo but a decent micro 9g size would be fine.

if using separate aileron servos, I would probably use 9g myself rather than 5g for peace of mind.

[ken anderson.]

erfolg.......the two I have used are MG's ones......zebra's are the brand.......I know you've mentioned putting one in each wing ....but I decided to follow the plan installation ....as the model is small and light------it doesn't req a lot of movement in the air - for the control surfaces.....

ken Anderson....ne...1 ........ movement dept.

[Erfolg]

Ken, I now put one in each wing, not because of any concerns with power etc. In my case, I find torque rods difficult/fiddly to instal. I find that drive to the arms of the torque rods can be a pain, that is for me. The other benefit I find is that it leaves the body area clear to stick my RC equipment and Lipo, where I want. I also have from time to time feed wing mounted servos through channels 2 & 6, which allows me to do all sorts of things with the surface from differential, flapperon.

Of course there is a down side, that is additional servo leads, more time in installing the extra servo and possibly weight.

I guess it all comes down to I find wing mounted servos easier and a little more convenient.

[Erfolg]

Graham, I have 2 off, Turnigy, 9g Metal Geared sevos, unfortunately, they are about twice the weight of a proper 9g.

[John Privett]

Mine has/had/will have again a similar layout to Ken's. 2200 3S LiPo up front, single servo for ailerons.

Where mine perhaps differed (I bought it s/hand from a club member) is that it had two elevator servos - one at each end of the elevator. I'm not sure what difference they made, the previous owner seemed to think they were "a good idea" - but then he would, as it was probably his idea!

[John Privett]

Meant to add, the motor in mine was a 2200kv "WASP" B2835 driving a 5.2x5.2 prop.

[Erfolg]

John, the use of two servos as you received your model, is I believe just a current trend, that is becoming a standard arrangement.

I have a couple of models using torque rods, wit a single servo. One being subjected to a revamp now. Unless done well, they can be problematic, from the support of the rod, the positioning of the support tube, often the linkage to the torque rods is not optimal, for a variety of reasons.In the the heyday of the torque rod assemblies, it was defacto, partly due to the high cost of servos, and the shear weight and bulk of servos.

Two servos on the other hand avoid a lot of the issues, particularly now that servos are much cheaper, the performance as high as the old standard servos, and much smaller and lighter. The down side is arguably the installation is multiplied by two. Then you have the servo leads to accommodate.

I have just ordered a D2826-6 and a few other low value items.

To-date, I have drawn out a new wing, printed out Profi templates, modified the print outs to suit the new wing. Mounted the prints onto card and then cut them out.

Tomorrow some time I will start the build.

Some photo will then be made.

Warning it will be a slow build, as I am very busy at present, plus I am slow. So all of you, the challenge is to beat me, the tortoise.

[John Privett]

Erfolg, not sure if you misread my point about the two servos... they're on the elevator. The reasoning being that with a single servo at one end of the elevator, the other end of the elevator may not move the full amount giving rise to a certain amount of roll. How significant that really is I have no idea!

[Erfolg]

John, yes, I got hold of the wrong of the stick.

The other problem is, that you are never certain if you are communicating with another long in the tooth modeller, or a new comer. In this case I was probably wrong on both accounts.

I am not certain about the additional servo. When you look at KC picture, the Lipo is well forward, which suggests that additional weight at the rear end may cause a CG issue. I had thought it could be easier just to increase the thickness or stiffness of the tail plane assembly. Then again that comes at a weight penalty.

I have been thinking that if there is a CG issue, I had been thinking along the lines of knocking about 10mm of the rear end of the body, to move the motor back, or should I say nearer the front.

In the case of this model, ballast could be a easy fix for CG issues, as the original model was designed and possibly constructed for a 400/480 motor and Nicads, all heavier that Lipos and outrunners. So a bit of ballast could be the solution that changes the least.

I have been considering the CG issue for myself, as a built up wing could be heavier. Plus the booms have to be deeper, which all could move the as built CG into a position where ballast could be needed. Hence the thought of how to deal with the issue, from a slightly longer nose, alternatively moving the motor position.

[ken anderson.]

erfolg in the past I've used a few different motors and on occasions had to add up to...20-30g on the elevator/tail.....one other point------I reinforce the joint between the boom and tailplane with some square(4mm)...as I've learnt in the past that if you make a mess of the landing...it normally breaks the joint at that point......my experience with pushycats is that they are very forgiving - flight wise...the stall is a none event and landing-they float on and on.......and land with a gentle flair.....also don't forget the cost of the materials....will be aprox £10.00...as most will be scrap wood......the only expense been the 100mm/6mm sheets for the wing and the 3mm for the booms...

ken Anderson ne..1..... more than one point dept....

[IanR]

Showing my ignorance - what's a 9 gram servo or a 5 gram servo? I've just had a look at the spec of a Towerpro MG90S servo, 9g according to Graham, and the figure "9" doesn't show up anywhere.

What are the Hitec HS55 servos, which I have 4 of, and will they do for my Pushy Cat?

[GrahamC]

Ian.. I think the normal term would be 'micro' servo. and yes - about the size of an HS55. Sorry if I've caused confusion, but I mean a servo that size. Of course when you add metal gears they get heavier - but they are still the same size!

I'm not sure that C of G will be that much of a problem with the extra 8 or 9 g. 

Here's the tail from my expired [Copy] PushyCat which went in so hard that the nose went in a good 2 inches. [RX or ESC Failure at the critical point of a full power loop] Odly enough, the tail was the only complete component!

This is 3mm [1/8th] medium balsa, with a 3 mm plate inserted to screw the servo to... the servo was shredded... but the 3mm balsa is completely intact! Hinging of the elevator was with top quality Scotch tape. I shall do the same on tis build... and if Erfolg convinces me to go to a 2 servo wing, I may hinge the ailerons in the same way!

 

Edited By GrahamC on 22/10/2013 12:21:20

Edited By GrahamC on 22/10/2013 12:21:58

[Erfolg]

Ahh! We now have two members who know something about the pushy cat.

From what has been written by KC a slightly thicker tailplane assembly could be useful. We also now know we need to build strong booms, as the bending forces on a less than perfect landing, could be an issue.

A little more on how the tail booms were re-enforced KC, as I know you know what the 4mm square makes reference to

Good stuff.

Ian, as Graham has written, 9g refers to a generic type. I suspect it all stems from Tower Pro, they made and still make some servos described as 9g, weighing, surprise, surplice, 9 grams. The other significant aspects were and still is they are both cheap and reliable. As with most spot on products, the same basic units appeared with different badges and also clones. Turnigy 90, Hextronic 90o, Tandarni 90. It does appear that there are differences in the material of the gear train of the Tower Pro and their badged siblings. Some have clearly a different circuit boards, well at least how it is positioned. I now buy all my 9g from HK, as they claim to supply a better gear train model as well as the basic model. Again as Graham has written, you can also buy the same 9g servo with a metal gear train, but at twice the weight. All are as cheap as chips, so you may as well go to HK.

[IanR]

So I take it I am OK to go with my Hitec HS55's?   Or should I find something with metal gears?

PS   This lad doesn't like Towerpro/Hextronic MG995 servos.   Granted, not the same servos but slightly worrying all the same.   http://www.rcmodelreviews.com/mg995review.shtml

 

Edited By IanR on 22/10/2013 14:11:24

[Erfolg]

Ian

Here is a link to the same site for HXT900, seems not so bad, or is that bad as in good?

[IanR]

Yes, you're right, of course, Erfolg. Thanks for pointing that out. I didn't look around the rest of his site but he's actually quite gushing about the HXT900 - the spec for which is virtually the same as my HS55's so I guess that means I can use them.

[WolstonFlyer]

Some useful information for potential Pushy Cat builders:

Due to my own plan woes, I have this morning spoken to Q&EFI. They tell me that they have plenty of copies of the back issue in question, and they are available in the UK for £6.15 including P&P [Thats what I think it cost!]

So If you want to join in with the build. Q&EFI are on +44(0)1684 588599 and the issue you need is January 2005.

Thanks for this Graham - I just ordered a copy of the January 2005 issue and it is £6.15 including postage. I Will put this plane on my extended "to-do" list, I like the idea of a nice fast delta wing

[Erfolg]

Ian

When it comes to radio gear, it is incredibly difficult to obtain an unbiased assessment of equipment.

I have used a number of manufacturers equipment, Waltron (which you will have never heard of if young), Sanwa and Futaba all have been fine. Non have let me down in use. I am presently using a club Hitec Focus 4, it works well.

The only servo I know defiantly failed in flight was an expensive make, not Futaba. When I got the model down, I found that a couple of teeth had failed. I was convinced that I was being knocked, constantly, one moment diving, the next climbing. Even now I am not convinced that the failure was not the consequence of a previous bad landing, or a knock in transport or storage.

Most (if not all) of my servo failures have been gear train damage, when I have caught a wing tip or something similar when landing.