Advanced Scale Models Pitts

[Darren 0]

I've always fancied a Pitts and after selling a few bits I find myself with some space sort of. Well, you can always make room can't you

 

So, after a bit of research it was shortlisted to the Cermark and the ASM ARTF's both of which are quarter scale and around 60" span. Jimbo & Brian have the Cermark so I thought I'd give the ASM a go.

 

It helps that it has been reviewed in the current RC Model Flyer, Ali at Avicraft gave it a recommendationa nd he could get me one in two days.

 

So I picked it up on Thursday, unfortunately this meant I couldn't keep it secret from Steve who has a well known Pitts fetish

 

Here's an official pic taken from the Ripmax site as I haven't had a chance to take any pictures yet.

[Darren 0]

The model construction is a little different, it is described as wood formers fitted with carbon stringers inside a moulded plastic skin. I couldn't quite imagine what that really was, but Ali convinced me that it was OK.

 

I though it would be a real thick heat shrink film fitted to the structure but it seems to be more like you would expect with a GRP fuse. A moulding in which the wood/carbon has been fitted. The skin is stiffer than I had expected, I think it will take the knocks of hangar rash, transport and general flying very well, if/when it needs a major repair it could be a different matter

 

The next issue was what engine, ASM say it's designed around the OS 120 III four stroke which is pumped and about £360 I'm really keen on the MVVS petrol engines but it would need a custom exhaust and that puts the cost up to similar levels. After speaking to Brian it was clear that for a Pitts you can never have too much power and it really benefits from keeping it light. He uses a Super Tigre 2300 in his Pitts and this lead me to the new OS 120 AX two stroke.

 

Half the weight of the OS 120 III fs or MVVS and more power, it claims to throw a 16x8 at 9000rpm giving over 15lbs thrust

 

The OS 120 AX is not a small engine but it's lost in the cowl, I've fitted the engine mount & engine - Ill take a few pictures later.

 

It should taken too long to get this assembled and I'll post thoughts/pictures as I go.

 

Of course you'll all be attending the club EGM on 30th and I'll be bringing it along for people to see in the flesh (plastic)

[Nutz 0]

Ohhh a Pitts,

Ohhh a OS AX,

Ohhh I like.

 

 

Can't wait for for the pics Darren.

[Darren 0]

The engine box is predrilled and captive nuts fitted, therefore if you're not going to use the recommended engine, I'd take some measurements first to see if it's close to the OS 120 size. The engine mount supplied has slightly slotted holes for bolting to the engine box so you've probably got an adjustment of about 5mm in engine width to play with.

 

The fitting of the plastic skin to the firewall on one side wasn't perfect and although nothing could go through it was a place that fuel could seep in. Also the OS 120 AX is light and I felt I cold therefore get away with adding a bit of weight. So, I used some lightweight glass cloth to skin the firewall and engine box, just to help hold it all together.

 

The engine is quite short and there is plenty of room behind it so I decide to mount a mini servo and have a direct throttle linkage.

 

One nice touch with the OS 120AX is the configurable exhaust. It comes with two adapters, one just extends the manifold so it sticks out more, the second twists the exhaust by 90 degrees. This means that if you mount the engine sidewinder, the exhaust is behind & below the engine Pitts style - that's handy

 

It you're tempted to pick one up, just a word of warning about the box. It's huge. With the back seats down in my large estate, it only just fitted in length ways.

 

Some pictures below.

 

 

 

 

 

[Darren 0]

the tailplane fits into the moulded slot and is glued in with medium cyno, at least that's what the manual says. The problem is that the flaired slot doesn't match the profile of the tailplane exactly.

 

So, how do you glue a contact patch about 10inches long with cyno holding the two surfaces together without making a mess and ending up with your fingers stuck to the model

 

The lower part of the tailplane slot fitted well so the bottom has been cyno'd in, and I've done one side of the upper by using epoxy and clamping a firmish piece of balsa along the top after protecting all the exposed parts with masking tape.

 

I'll take a picture before I unclamp it later, let's hope it's worked and doesn't look a mess. I guess a piece of covering could be used to rescue it if it doesn't work too well.

[Darren 0]

A few more pics. The epoxy method seems to have done the trick, one side done the other gluing at the moment.

 

Also, I didn't think the earlier pic of the 120 with the irvine 53 really showed the size difference so I took another one.

 

Finally, I've temporarily fitted the cowl, a 16x6 prop and spinner just to get a feel for how it will look. I'm happy

 

 

 

 

[Lofty 5]

I've had my hands all over afew of them kits, hehe may an hour has be spent day dreaming at work looking at the big box!

 

And like you said! Its a close fit in any car ...........

 

Make's me want one so bad!!!!!

 

If / when I do get one, I'm going to putting in a SC 280 engine in it Or something like that!

 

Anyway back to real life, I think I'm going to leave getting one for abit, still leaving alot about big birds from may a cumster at work!

 

Can't wait to see the Pitts at club night

[Jimbo 0]

Looks nice dazzle - I like that exhaust system on the AX - neat!

 

You going to wait for me to come home before you crash it though?

[Darren 0]

OK, a bit more progress - I can't emphasize how quickly this is going together - I'm only doing 30 mins or so at a time.

 

The cowl mounts are nice items, you bolt to the firewall and then screw through the cowl. I've tried to soften the mounting a bit with thin 'fuel tube' washers on the mounting screws.

 

I've also decided that the silencer out pipe wasn't going to work so I've twisted it through 90degrees and cut a small outlet. I did hope that I'd be able to route the exhaust out the scale position but it would need about 4" of silicon tube - just a bit too long.

 

Also fitted my pilot. It's a 30% World Models sports pilot and I think looks real nice.

 

My order of APC 16x8 props arrived and I've fitted a spare Ali spinner so with the exception of a hole for the glow driver the front end is just about done.

 

 

 

 

[Lofty 5]

Not to put a spanner into the works and you most likely will not care anyway ..........but I'm sure it should be a female pilot as this Pitts colour s "Yellow & Black" is from a real female pilot colour shceme!

 

Anyway I'm just nit picking, because you have one and I don't

[Darren 0]

Yes I know, but I couldn't find one of the right scale that I wasn't going to have to spend more time painting than building the model

 

Anyway, I don't really care

[Her Klunk 0]

I see you have managed to find a pilot who looks just like you....

[Darren 0]

If only I was that handsome

[Darren 0]

Well there is a mix of news, some good, some great, some dubious and some bad.

 

The good news is that it really is nearly finished, install elevator & rudder servos and pushrods, put in the tank and fit a switch.

 

The great news is that the OS120AX has been independently tested giving 15.5lbs thrust with an APC 16x8 and I've just weighed including a bag of the bits still to be fitted and it's about 10 lbs

 

The other great news is that the thing I was due to do on Sunday has been cancelled and although it's last sunday, I might get it to the field this week - although it will only be for engine running.

 

The dubious news are the horns supplied for the interwing linkage, not impressed They seem to be made of tuff card but just don't seem to be up to the job to me. I've got some carbon fibre angle, might need to make some new. At the very least I'm going to glass cloth the originals.

 

Also, I'm never very impressed with horns, linkages, pushrods that you get in kits so I've dipped into my supply of pete tindal ally and carbon rods and fittings - I wouldn't use anything else.

 

And the bad news is that it won't fit in the car already rigged - but that was a long shot anyway

Edited December 17, 2006 by Guest

[Darren 0]

......... oh and before anyone mentions it, there are spats and shaped & coloured undercarriage covers to fit.

[Darren 0]

OK, more thinking about those interwing linkage horns and I've decided that glassing the originals is going to be much less work than making new.

 

I've a length on 90 degree angle carbon fibre if these don't prove to be up to the job.

 

Below are the during and after shots

[Darren 0]

Right, the rudder & elevators are all fitted and working, a short servo extention added to the throttle and that's OK, tank is in and plumbed, wing servos/horns/linkages fitted and set-up and the main switch fitted.

 

The interwing linkage horns have been re-fitted but I haven't rigged the model yet to see if they are any better

 

I decided to cut a hole in the cowl rather than try and mount a remote glow somewhere and I haven't decided what to do about the needle valve yet. Because it is angled it would need a largish hole in the top of the cowl. I'm thinking about fitting a boden cable as a flexible extension and hanging out the back of one of the cowl cheeks.

 

So other than the needle valve, all there is left to do is mount the receiver and battery and add some decals. So it should be finished today.

 

Given the weather I don't think my idea of getting to the field and running in the engine is going to happen. Oh well, there's always next week

[Nutz 0]

Darren,

My AX came with some wire and a collar, I now know what it is for

 

[Darren 0]

Yes, mine too but it's not long enough. Also a bit worried about it rubbing if I do what I plan, but a bit of heat shrink over the cable will help.

 

I won't do anything before Thursday and the EGM and you can all offer your thoughts on the matter.

 

I have now just rigged it all and it balances spot on. So battery to be fitted properly and fit of the spats and she's deon

[Darren 0]

 

It's finished, left & right interwing struts colour coded, spats on, ready to go.

 

All I need now is some good weather and a chance to run in the engine.

 

I'll get some final rigged pics at the EGM this week. See you all there

[Jimbo 0]

Mmmmmm nice......

 

I might even be up the field on the 17th!

[Darren 0]

Well if the wind ever calms down I might make it too, but I'll have to decide if I bring this or my other new plane

[Darren 0]

 

I wondered who'd crack first and want to know more!

 

It was a bargain purchase and one with a justifiable purpose and an engine you'll be pleased with.

 

I've been on the look out for something that can double up as a toffee bomber at the show. Managed to pick up a 2nd hand 1/4 scale clipped wing taylorcraft with a 26cc petrol (evolution i.e. MVVS) for less than the cost of the engine.

 

I'll post some pics in a new thread.

 

I've also been asked to do a RCMW review of a sports model - don't know exactly what it is yet but I'm expecting a box from Traplet soon

[Lofty 5]

Weather is looking good for Sunday atm!

 

Plane is a GO,

Pilot is a GO,

Weather is a GO...... "Lets hope"

 

Can't wait to see her in the sky, had a good look over her at the EGM last Thursday, but wasn't good enough......want to see her fly

[Darren 0]

hmmmmm

 

The met office are reporting 26mph winds and rain for sunday