Jonathan M

Thanks for the advice and the reminder about weight and style. A sealed tank-bay is a good idea, stronger structure for less weight and less scope for fuel residue to enter; it would also allow half an inch off the nose as the 4oz tank could then, if need be, protrude a bit aft of F2. I've gone ahead and ordered A2 plans from the local print shop. Not expensive and I've asked them to print to 50% grey so I can pencil possible mods over it more easily. Also asked them to print a mirror of the right wing sheet so I've got a separate identical plan for the left wing. I think the way this is all pointing is towards the Amelia... when one's fallen for a girl it's hard to look at anyone else!

Piers, good point about an IC-specific design, although a conversion from electric isn't a real impediment if it comes to that. I saw the tiny photo of the Alley Cat on Sarik's website a bit ago but couldn't find any more images or information on it anywhere, nothing as far as I could see anywhere on here. In the end I assumed stubby nose, little or no dihedral and general Miller-ness of approach, which is fine but too little to go on. Maybe you'll finish your's sometime...? What wee beastie would you put in it?

Graham (just seen your post which came through just as I was posting mine above), that's really helpful, thanks. I actually ordered the Peggy Sue plan the other day, so its still in the running... and even if not now perhaps as an airframe for a second 30FS model some time!?

Antony, thanks so much for the positive feedback on the Amelia. I'd be happy to build it as designed and at 47", except for the fact that on another thread it was reported by someone who flew one that it seemed very 'nose-heavy', although who knows where the builder put his CG (the plan shows it at 28% from the LE)? The 30FS isn't really any heavier than the 26 but, as the CG almost certainly needs moving back a bit, shortening the nose a tad (in the fuel bay between F1 and F2) might avoid adding weight at the tail? Also the wing is seated at 0° incidence which would mean up elevator trim all the time for S&L flight, so I'd tweak that to give a clear 0.5° positive. Although mindful of not adding excessive extra weight, I'm still inclined to sheet the forward wing underside as well as spruce spars. There's no reason why the wing cannot be bolted on with nylon, and I'd prefer a neater wire undercarriage solution that fixes to the fuselage at F2 instead of hinging on the wing and flopping about with oily rubber bands. All these musings are happening because the Amelia has somehow caught my eye... one can't spend ages building a model one doesn't completely fancy, can one!?

Very helpful advice, thanks Denis. One design that I really rather fancy is Dereck Woodward's 47" Amelia originally for 20-25 four-strokes, so maybe the 30 Surpass would be too much power or too heavy in the nose? I could get the plan printed at say 111% to bring it up to 52" which would also helpfully reduce the wing-loading a bit? Or shorten the nose moment by half an inch? Other things are easy to tweak to give a slightly less cartoony look, e.g. give the canopy front a bit more slope and make the tail outlines a bit less pointy without reducing their surface areas. The wing is apparently weak as it employs hard balsa spars instead of spruce and has neither sheeting on the underside to make a full D-box nor sheer webs, but these things are easy to alter at the plan stage. I'd fit separate servos in each wing half, and possibly consider inset ailerons instead of strip ones. The undercarriage wire can be made to bind to the former in front of the wing LE instead of clamped to the wing? So plenty of scope for minor changes to suit without radically changing the basic format - much easier than designing something from scratch!

Mini Astro Hog is really lovely thanks Frank. Pretty close to the thing I'm looking for in terms of aesthetics etc, and I do fancy the inset ailerons, but I think its much too small for the 30FS (article says don't go above a 15). Something closer to 50" span should have a lower wing-loading and be easier to see. One could I suppose scale up slightly (or scale down a design that's a bit too big to start with), but I'd lack the knowledge to know which primary structure components would need to go up (or down) in thickness or section. It seems easier for me at this stage to work off a plan that's fully resolved, and only tweak minor things to suit (e.g. separate wing servos rather than bell-cranks or torque-rods).

Yes, CB lovely, have the plan etc - but looking here for an airframe for the 30FS.

Gosh, that's a good suggestion... here's how Didier flies his on a 26FS... more than astonishing!

Thanks Jon - I didn't mean actual 'garden' grade, it was just a turn of phrase really. I was looking at MSL's own basic fuel tubing

See What Sports Aerobatic for an OS 30FS thread.

Having recently moved close to a club which permits IC but is in public space (where keeping the noise down is basic good manners) and has a much smaller mown patch than my old one, I'm looking to build a sports aerobatic to be powered by my never-yet run OS 30FS. The sort of power flying I normally prefer is closer to the more traditional Gangster 63 Lite type of classic aerobatics (but not super-fast) rather than the antics of fun-fly etc. My first thoughts were for a low-wing tail-dragger design circa 47-50" span but not yet found a plan that I really like or ticks all the boxes. However I have been studying Peter Miller's original Peggy Sue 50" plan and article which is certainly very attractive (curvy but not over-complicated to build) and I'm sure perfectly aerobatic, and the high-wing (constant chord, no dihedral) format has its advantages. But before I take the plunge, I'd really welcome any other suggestions. Could be plan, kit or short kit. Would be happy with tapering wing construction if necessary. Tail-dragger more practical for the new patch. Enclosed cockput preferred, but not essential. Etc.

PS - Any suggestions on fuel tube type? Any reason to not just use common-or-garden 3/32 clear silicone? (My old box of tubing, spare tanks, clips, bungs, filters etc has all gone so I'm starting from scratch again.)

Suggestions would be interesting and welcome, but I think I'll start a separate thread for that. Stand by...

Pete - good to hear your experience and the extra detail on Bektra, thx. Jon - thanks for the advice on running it in, and the pre-oil too. I'd read the instructions through a couple of times, your method effectively does the same thing in less time. BTW I needed to move home a year ago and, with a ton of stuff to lose from the old gaff plus thinking I was going to wind up in an urban flat, I needed to be radical and took the decision to sell my IC models, and gave away associated kit and sundry accessories to a club-mate. I did however keep my modest collection of mostly NIB engines (this OS 30FS, a 35AX, a SC32, the ASP 70FS from my old Acrowot, and a Laser 80). I'm now actually renting somewhere with a garage and small garden, so I have recently bought back the Irvine 53-equipped Gangster 63 Lite I built a couple of years' ago and my flight-box etc. The local club is very close by and fine with IC (although everyone else flies electric) but the Gangster really needs a bigger patch, and I'd prefer to keep the noise levels down for the broader (future) benefit of the club, hence the decision to to get the quieter 30FS up and running and build a suitable model for it... what that model might be will be the subject of a separate thread! PS - how come I can't buy any 1/8" fuel tubing anywhere?!

Thanks to everyone who's contributed. The next step (and ultimately more important I'm sure than the choice of fuel) will be to ensure that I run the engine in as carefully and fully as possible.

I wasn't asking about the best fuel or anything else, I was asking about Bekra. Just a simple yes or no will do, thanks.

I have an OS30 four-stroke, bought new a few years ago, which I'm about to run in (and for which I'm about to build a suitable airframe). I very happily use Model Technics Bekra 10 (18% mixture of EDL and Klotz oils) in my Irvine 53 - I particularly like the fact that the residue it leaves on the airframe is relatively un-sticky, etc. Am I correct in assuming the wee modern four-stroke will run perfectly well on this, from run-in onwards?

Kevin - any feedback from your apprentice on the offerings so far suggested? In the meantime, here's another one to consider: Coachman 53in for .20 to .30 engines

Here's my own 'summer floater' (also running E-Soar Plus which is a great template for anyone using OpenTX), an Austrian kit called the FXj 2.5m which I recently finished and have already maidened. I didn't build the original but bought it a while ago from a chap who had done so as a pure bungee-launched glider and then covered it in heavy Oratex for some bizarre reason, then never flew it. I stripped it all back to balsa, converted it to electric launch with a geared Reisenauer motor, re-did all the servos etc, and re-covered it in Oralight. While I don't see it being as competitive as a 3.5 or 4m F5J ship, first test flights show it to still be extremely capable... a very good minimum sink rate, burns rubber as soon is it goes into Speed mode, and can certainly handle more boisterous conditions than the 2mRES models I've been flying for the last two or three years. We'll surely get some calm sunny days over the coming months...

Who knows what excess flying loads or landing-shocks your club-mate's Amelia might have had before that fateful day (a progressive weakening of the wing) but looking at the plan there's certainly no sheer-webbing shown between the spars - however this is an easy fix. The other mod I'd make is to fit separate aileron servos. Re being nose-heavy on the sticks, I wonder whether that was simply because the CG was too far forward? For my part, also, I imagine the 30FS might be too heavy or too much for this model - unless it was scaled it up say 10%?

Cheers Andy Truth be told I was in a bit of a flap last Autumn having suddenly sold my house and thinking I was going to wind up in a rented flat with no scope to store let alone run-up IC models! As it happens I've now got a place with a garage - damp and cold in winter but at least its a garage! - and I was feeling real bad about having let the Gangster go...

Just to say that I'm feeling rather chuffed, as the club-mate I sold my own Gangster Lite to a year ago has agreed to sell it back to me... 😀

Another alternative is the 47" low-wing Amelia by Dereck Woodward. This is also very nicely scale-like, also with a semi-symmetrical wing for more engaging flying performance, but would be simpler to build than the Peggy Sue, and has the advantage of an upright engine configuration (20 2-str or 25 4-str) with removable hatch for easy access. Amelia 47" Plan & Article (I'll confess to a personal interest here, as I have a NIB OS 30FS looking for a suitable airframe... and several currently-unallocated winter building months ahead!)

I'd agree with kc - if a design captures the imagination then that's pretty critical as it'll provide a huge amount of positive momentum even if the build level is a bit more 'intermediate' than 'beginner' and takes a bit longer. And you say he's been flying foamies for a while and is currently building a Mignon? In that case something like the RM trainer, while providing more basic building experience, isn't going to excite him construction-wise, nor will it be that interesting in flying potential (flat bottomed wing) to take him to the next level. How about looking at the original Peggy Sue design? Bang on 50" span, semi-symmetrical section, for 20-25 two-strokes (or 26-30 four-strokes) and a reasonably modest wing-loading for its size of 17oz/ft2. Peggy Sue 50" Plan & Article That's all assuming that you're happy to continue to mentor the lad and guide him through the more tricky bits...!?

Nigel, you're right to question my use of published figures for IC motors etc. I'd dug out for my comment above the various calculation notes I'd made when I had my Wot4 and my Gangster, but ultimately my views are based on actual flying experience of both models. The bottom line for anyone building a Gangster 63 Lite as a proper classic aerobatic model for a range of flying conditions rather than something to pootle around with on a nice day, is that it'll be a pointless exercise to fit an under-powered motor / powertrain. If someone wants a super-light Gangster, e.g. MR's 4lb model quoted on his website (which George has presumably based his calcs on) and is happy to fly each Lipo for just a few mins before swapping it out, then equip it accordingly. I liked mine at 5.5lbs - lighter than the original, but still with the energy (both weight and thrust) to perform as a classic aerobat. If I'd wanted a light wing-loading floater or an overpowered modern hooligan then I'd have chosen another design.