Grant Webb Posted April 11, 2016 Share Posted April 11, 2016 Hi guys. I'm considering "re-building" a Brian Peckham design Chippertoo. I first built this model back in the late '80s and powered it with an OS 40 FSR, with which it flew fairly spritely. Unfortunately I lost both the engine and the model in a massive crash from height following radio failure. Anyway, my question is, would my new Saito FA-40 be a suitable replacement for the older technology OS engine? Comments appreciated. Edited By Grant Webb on 11/04/2016 10:56:47 Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted April 11, 2016 Share Posted April 11, 2016 Go for the 50 . The 40 is a great engine but a bit lacking in power . The 50 FA should be nearer to the FSR in power and should fly you Chippy OK. Quote Link to comment Share on other sites More sharing options...
extra slim Posted April 11, 2016 Share Posted April 11, 2016 strictly speaking mate, the answer is no...BUT...it depends on how big/heavy the old one was and the new one will intend to be. If the old one was a tad overpowered with the FSR, and if you build a lighter weight version now using modern equipment, it would probably fly it, swinging a bigger prop and possibly more scale....but iMO it would need to be a lot lighter to cater for a 40 FS compared to the superb FSR motors. Just my thoughts. Quote Link to comment Share on other sites More sharing options...
Tomtom39 Posted April 11, 2016 Share Posted April 11, 2016 Bit off field but I've bought the Enya 41 4c its a cracking little motor - bit more expensive than the suggested Saito. If my memory serves me than I seem to recollect that the Saito 50 has been replaced by the 56? I got mine from Steve Webb models Quote Link to comment Share on other sites More sharing options...
Former Member Posted April 11, 2016 Share Posted April 11, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
extra slim Posted April 11, 2016 Share Posted April 11, 2016 just noticed a build thread of one of these by silver wolf on here..he is pondering a laser 70 or 80, so Percy's suggestion of a saito 62 for me is bang on Quote Link to comment Share on other sites More sharing options...
Grant Webb Posted April 11, 2016 Author Share Posted April 11, 2016 Thank you for your advice, guys. I had wondered if it might be a little under powered. I have spotted a couple of second hand FA-50's on the old E/B, but am more inclined to go with the '56. I already have an OS 70 Surpass which I felt might be a little big, so the '56 would be a nice intermediate step. Will have to start hiding the good lady's cigarette change! Thanks again. Quote Link to comment Share on other sites More sharing options...
Grant Webb Posted April 11, 2016 Author Share Posted April 11, 2016 Posted by extra slim on 11/04/2016 14:41:40: just noticed a build thread of one of these by silver wolf on here..he is pondering a laser 70 or 80, so Percy's suggestion of a saito 62 for me is bang on Hi, Slim. I have seen that posting before. The model there is a scale Chipmunk. The Chippertoo, although styled on the Super Chipmunk, is in fact a sport design - not scale. I just loved it's scale'ish appearance though. Cheers, Edited By Grant Webb on 11/04/2016 23:37:20 Quote Link to comment Share on other sites More sharing options...
Former Member Posted April 12, 2016 Share Posted April 12, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
will -0 Posted April 12, 2016 Share Posted April 12, 2016 Posted by extra slim on 11/04/2016 14:41:40: just noticed a build thread of one of these by silver wolf on here..he is pondering a laser 70 or 80, so Percy's suggestion of a saito 62 for me is bang on Oo I would'nt go for a 70 or 80, better put a 90 or even better a 120 for good measure. Quote Link to comment Share on other sites More sharing options...
extra slim Posted April 12, 2016 Share Posted April 12, 2016 Will -0...Grant pointed out the error in my ways as the thread was titled chipper too but was as grant pointed out a scale beastie, and alot bigger..The model he refers to is only 57"...so Percy's advice I reckon is the one to follow.. Quote Link to comment Share on other sites More sharing options...
will -0 Posted April 12, 2016 Share Posted April 12, 2016 Sorry, I was being slightly naughty making a point about engine power inflation. Sure you can overpower stuff if you must, but it's not obligatory! All depends what sort of flying you want to do. Quote Link to comment Share on other sites More sharing options...
Alan Gorham_ Posted April 12, 2016 Share Posted April 12, 2016 Hi Grant Just wanted to say I love the pics of your old Chippertoo, it was a classic design and a classic engine and you did a great job. The OS 40 FSR was a decent engine of its time at around 1.2 HP and was frequently used with a 10" x 6" prop. I think I would echo the consensus above of a Saito 62 or a Laser 70 four stroke. Both will turn a bigger prop at a lower rpm, but the power delivery will (in my opinion) suit the style of the model more than the 2 stroke did. One of my other considerations would be to try and hide the four strokes cylinder in the cowl, so that would guide my choice too. I hope you do go ahead with the model! Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted April 12, 2016 Share Posted April 12, 2016 Consider carefully Grant, strapping the suggested 1lb weight on the front of your Chippertoo, Which is a 5 foot span 40 model? Give the Saito a chance, with a strong light build from your board Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted April 12, 2016 Share Posted April 12, 2016 Saito 40 btw Quote Link to comment Share on other sites More sharing options...
Former Member Posted April 12, 2016 Share Posted April 12, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Alan Gorham_ Posted April 12, 2016 Share Posted April 12, 2016 Not sure that's right Percy...I looked earlier and you can get a Saito 62 from Kings Lynn models for less than 150 of the Queen's pounds, but the Laser is around £210. I think that provided I could enclose the head in the cowl, I'd choose the Laser over the Saito though. Some reasons: The Laser has it's timing gear tucked away behind the cylinder, so it's protected in a crash (not that I crash very much, but you never know). The Laser is around 150g heavier than both the OS40FSR and the Saito 62, making it less likely to need nose weight to balance the model. The Laser doesn't need or have provision for silencer pressure, so the plumbings easier. I think I would cut a decent sized exit in the lower part of the cowl for hot air to exit and I reckon I could get a finger to the Lasers carb to choke it for easy starting (I don't own or use an electric starter) and this means one less hole in the cowl for the choke lever and I probably could arrange for the needle to exit the cowl in the same place as the hot air did. Quote Link to comment Share on other sites More sharing options...
Shaunie Posted April 12, 2016 Share Posted April 12, 2016 I had (in fact I still have) an OS45 FSR, it was without a shadow of doubt the best glow motor I ever owned. I would think that to equal your 40 you should go for a 60 class four-stroke. If you have two much power you can always throttle back, if you have insufficient power on take off you can always build another plane 😜. Shaunie. Quote Link to comment Share on other sites More sharing options...
Grant Webb Posted April 13, 2016 Author Share Posted April 13, 2016 Lots to ponder .... thank you all. Will-O .. thank you for your well thought out advice - however I tend to be a flyer at the other end of the spectrum, erring more towards flight realism than brute force and speed. The aeros I do I prefer to fly them, not drag through them. Thank you for your comments Alan G. - I was aware of the h/p difference between the Fa-40 and the 40 FSR. The Saito is rated at a mere .65h/p at 10,000rpm while the 40FSR's 1.2h/p is attained at 16,000rpm. But I also understand that h/p is only part of the story, with 4stroke engines being torquier and capable of swinging larger props - hence my confusion. Cheers all... Quote Link to comment Share on other sites More sharing options...
Former Member Posted April 13, 2016 Share Posted April 13, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Alan Gorham_ Posted April 13, 2016 Share Posted April 13, 2016 Grant, yes you are correct that 4 strokes are torquier, but a Saito 40 won't end up giving the same thrust as an OS 40 FSR and that's the key at the end of the day. Percy, I agree with you up to a point: manufacturers quoted HP figures can be misleading as it is often not clear what parameters were applied during the HP test (i.e. fuel used, prop fitted, open exhaust or silencer fitted) however some of the "ye olde" magazine engine tests such as those done by PGF Chinn or Mike Billington were done on a dynamometer and as such they produced a torque and HP set of curves. Couple that with their rpm measurements on certain prop sizes and makes, it then became possible to prop your engine to make best use of either the peak power (screaming rpm) or low down grunt (torque) depending on your requirements. Quote Link to comment Share on other sites More sharing options...
Former Member Posted April 13, 2016 Share Posted April 13, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
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