What shall I build using this as a powerplant?

[Martyn K]

Just happened to be browsing on FleaBay the other day and spotted that this was about to be sold with 3 minutes left to go. So I punted and got it for £51.00

Its a ST 3000 (32.5cc 2 stroke glow) and as far as I can see it hasn't even been run in (although the seller said that is had been. It's certainly in mint condition and never been flown..

and

Its got the optional radial mount and a Pitts type silencer.

Soooo, I need to decide what to put it in.

Not interested in ARTF, RTF and to be honest a kit would probably be too expensive - even if one existed.

My preference would be for an IMAC style aerobatic model - I would really like a plan build but prepared to draw my own up.

My thoughts are possibly a CAP-21 or CAP-232 (not an Extra - common as muck), or perhaps a Pitts or possibly something like a Bucker Jungmeister or other aerobatic bipe. Note my interests are really precision not 3D aerobatics. I am not looking for a class A scale model, but perhaps something that may pass for an original on a very dark night down an unlit street. You get the idea

Anyway - I am open to suggestions - especially for suitable leads for plans etc (if they exist).

Your thoughts please maestros

Best wishes

Martyn

[Martin Whybrow]

Something with a large fuel tank

Worth converting to petrol considering how much glow fuel it will use I would have thought.

[Martyn K]

Hi Martin

I always judge a models potential fuel consumption by the size of the carb intake. It's not much larger than a standard 90 sized motor so I presume that it has been optimised for peak torque - large diameter props - rather than out and out horsepower.

A petrol conversion would be interesting though - need to get hold of the special carb though

Martyn

[Richard Harris]

Martyn,

Make sure you use model Technics 'Big Brute' fuel as this was developed for this range of motors, especially with the ST 3250 as it has a tendency to backfire in the air on standard 2 stroke fuel.

What about the big Jabberwock ? I had one with the ST 2000 fitted and it flew well, would be even better with the 32cc.

Rich

[Martyn K]

Thanks Rich

(for the idea and the fuel warning)

I'll take a look

Martyn

[mal brewer]

Hi Martyn,
fabulous engine,I used one for years (still got it) in a 1/4 scale biplane of 72" span.It never missed a beat,and I could almost guarantee a first flick start.I ran mine on straight fuel (i.e. no nitro) with 10% oil content.You must be careful to set them slightly rich on the ground,as they unload and lean out quite a bit in the air.They will convert to petrol,but I never bothered to do that,as has been stated , they are fairly economical,and the straight fuel with low oil content doesn't cost a fortune,plus of course,they are quite a low-revving engine.........Mal

Edited By mal brewer on 14/12/2013 23:28:06

[Bob Cotsford]

Jabberwok's are definitely retro but hardly precision aerobats. How about a 1/4 scale Dalotel, a fairly straightforward outline and a bit retro into the bargain.

[jeff2wings]

Pegasus models Laser 200 ,80" span £130 for the kit ,bargain

[john stones 1 - Moderator]

how about a zlin. that engine would fly it at scale speed

a mate had a skyways plan pack with st 2500 in, flew a treat

he only ever used straight fuel. never had problems with it.

[Former Member]

[This posting has been removed]

[mal brewer]

Martyn,
Keith Mitchell of the LMA described converting the ST 3000 to petrol.It was many years ago in,I think,scale modeller quarterly magazine.He used four of them in his Lancaster.It may be worth finding the article,or maybe contact the LMA for information.......Mal

[karl grey]

How about a hostetler giles 202 plan from belair kits scaled down to suit the st3250. About 27% scale. Would be great for some IMAC aeros.

[Martyn K]

The Giles 202 looks cool - The Hostsetler is a bit large, but this looks like a good candidate

I have also been considering a scratch built Pitts 14 - about 28% scale, there are a couple of models around, but none at the size that I will need to build. Its a very simple layout - parallel chord wings etc

and

A couple of options here and the sort of thing that appeal.

Traplet have a Zlin 526 plan (and parts) available - 82" span, the size looks about right but this rated for a 20cc engine, I am not sure how the airframe would cope with a 50% increase in capacity. Your thoughts would be welcome as this would probably be the easiest option.

The Pegasus Laser 200 does look incredible value, but the Pegasus website has very little info on this model - ie how much of a constructors model it really is. Can anyone shed some light on this please?

Petrol conversion - thanks, I'll see if I can find the article

Thanks for the ideas - keep them coming

 

Martyn

Edited By Martyn K on 15/12/2013 22:04:13

[john stones 1 - Moderator]

50cc petrols are being used in 80 odd inch airframes martyn

ive a 30cc in a 68 inch artf su 26.

a Zenoah 26 in a glens cap 68 inch

[Tony Richardson]

Martyn I had one of these engines in a Balsa USA Citabria Pro, it was certainly not a speed machine more like the old Dennis double decker bus ( lots of power and torque at not a high RPM ) would go vertical at about the same speed as level flight, great engine for scale models where speed is not the main requirment, flew mine on an 18x8 but was advised a 18x10 or even 20x6 would be suitable it certainly had the torque for large props entirely different engine than the 2000 or 2500 which are higher revving engines, for its size it is very easy on fuel burns way less than my Saito 180fs. Find the right model and enjoy.

Ps how about a large scale Beaver or maybe a Lysander. NOTE spares can be hard to find as this model has been discotinued bearings "if needed" can be sourced from Boca bearings and there is a guy in the US that custom makes piston rings, google the ringmaster and you should be able to find him his first name is Frank can't remember the rest but if you need it PM me and I will search it out, have fun.

[Martyn K]

Another option worth considering is this Starduster from RCM plans.

72" span (T), 65" span (B), 1464 sq. in., 1.2-1.8, 4 ch., built-up balsa and plywood, three sheets 34" x 66-3/4", 34" x 74-3/4", 34" x 72-3/4"

Lots of colour options as well.

Anyone got any experience of RCM plans?

Martyn

[Former Member]

[This posting has been removed]

[Luther Oswalt]

I have no present day experience with RCM plans but every thing I read says stay away from them! Accept funds and never deliver the goods!

Leo

[jeff2wings]

Martyn , Laser 200 is a trad foam/balsa build ,has two piece wing IIRC .Have you looked on www. outerzone.co.uk ?? and stay away from RCM !

[Martyn K]

I am staying away from RCM - thanks for the warnings.

My inclination is to go for a totally scratch built Pitts Model 14 (see photos above).

A 28% scale model would give me:

Wing Span 72"
Chord 12"
Area = 1772 sq "
LOA = 65" (spinner to end of rudder)

(all numbers rounded up/down to the nearest integer)

I have managed to get 3-views and converted them to CAD format, so its a fairly simple task to scale up to 72" span and then build a structure around it. I can do easy bits first - like the fin and tailplane and work it out as I go along. Some bits aren't especially clear but there are lots of full size construction photos available

This meets most of my objectives for the model - it will be quite a slow build as it wont be cheap and I will need some help sizing some of the structural components - so it will be a real team effort. A bonus is that it will be unique

If the consensus is 'go for it' then as usual, I'll share the plans if anyone wants to build one in the future. If you say 'run away' then I'll probably go for a home brew CAP 21 or 232 - or perhaps the Traplet Zlin plan.

Your thoughts please maestros...

 

Martyn

Edited By Martyn K on 17/12/2013 21:53:56

[Concorde Speedbird]

Do the Pitts design, it will be cool. 72" for a biplane is huge, I think with that engine a bit smaller would give better performance, but it is hard to tell without seeing some plans.

CS

[Martyn K]

Hi CS

I saw you were online and guessed that you would vote for the Pitts. I went for 28% because the Pitts Special at 25% (1/4) is usually sized for a 61 2 stroke and a 33% usually gets a 50cc Petrol.

It just seemed about right in the middle.

Martyn

[john stones 1 - Moderator]

question is Martin what do you think ?

you've a good selection, which one do you really fancy

[Martyn K]

Hi John

I am very tempted with the Pitts 14. Mainly because there isn't another one - I don't even think the prototype has flown yet although these has been one or two smaller 14s built, there is nothing around at this size as far as I can see.

At less than 2m span, I don't have to worry about 2 piece wings which should simplify things a bit. It wont be Class A scale - however, it will be recognisable - stand off scale will be OK. (Stand off about a mile away and it will be perfect.

It also has some nice easy to build bits - like parallel chord wings, means I don't need a laser cutter.

I should be able to keep the weight below 7kg as well. Finally, it looks right although I suspect it will be quite hands on to fly

The down side is that it will take longer than a straight kit or plan build as I will have lots of things to work out in the process. However Herri's 1/3 Pitts Special build blog will give me lots of ideas that I can crib

Martyn

[David Tweddle]

Posted by Martyn K on 17/12/2013 21:53:18:

If you say 'run away' then I'll probably go for a home brew CAP 21 or 232 - or perhaps the Traplet Zlin plan.

Your thoughts please maestros...

Martyn

Edited By Martyn K on 17/12/2013 21:53:56

Run away Martyn, from those things and go with the Pitts please, so much style and I just love the lines and looks of her.

Regards David