Bearair Posted November 1, 2013 Share Posted November 1, 2013 Hi A few years ago I bought a Dirty Birdy for renovation. It is 60inch span with a glass fiber fus. I think it may be from the Svenson kit but im not really sure. I was thinking of using a Rossi 53 with tuned pipe for power. Weight is 4.5lbs without engine, tank or radio. What are peoples thoughts on the Rossi as a engine for it or can someone suggest a more "authentic" engine. Will post some pictures later. Roger Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted November 1, 2013 Share Posted November 1, 2013 Mmm, well you'll certainly have plenty of power - as in "zoooooooom". I've never had a Rossi engine but the ones I've seen have left me with the impression that - on song - they are excellent - but that getting "on song" is a bit of an art form! BEB Quote Link to comment Share on other sites More sharing options...
Martyn K Posted November 1, 2013 Share Posted November 1, 2013 Hi Roger I am just a beginner here, but I would imagine that a modern 53 will be comparable power wise against a period 61 - with the bonus of probably being lighter. Do you know if it will it swing a 12x8 prop at suitable RPM? Martyn Quote Link to comment Share on other sites More sharing options...
Bearair Posted November 1, 2013 Author Share Posted November 1, 2013 Been running Rossi 40s for many a long year, but the 53 will be new to me and so will a pipe! Quote Link to comment Share on other sites More sharing options...
Hangar 9 nut Posted November 1, 2013 Share Posted November 1, 2013 I agree with Biggles they are a bit of a handful so I would go for Super Tigre,Webra,OS or HP,all plentifull second hand I have a Hangar 9 Phoenix 7 with OS 55,plenty of power so you have a big choice to pick from but stay clear of Rossi ! Also you have Evolution from Horizon at a good price! Edited By tony bloomfield on 01/11/2013 12:50:26 Quote Link to comment Share on other sites More sharing options...
Bearair Posted November 1, 2013 Author Share Posted November 1, 2013 Hi Martin, Not sure what it will do not run it yet. Going by the forties ive had im expecting to need to rev it to get top performance. A forty works best with a 9 6 so not sure if a 12 8 will be to big for the 53. If anyone has expeirence of this motor it would be very usefull. Quote Link to comment Share on other sites More sharing options...
kc Posted November 1, 2013 Share Posted November 1, 2013 It's outside my experience as well, but I reckon the weight (or lack of weight of the Rossi) might be the factor to consider. An old .61 is probably heavier? The fibreglass fuselage wont be lighter than the balsa original which was 128 onces ( 8 pounds ) ready to fly according to the article in RCM June 75 and July 75. (I have the magazines)In theory this plan is still available from RCM Plans in USA but lots of people have reported problems getting RCM to deliver what they have paid for.Edited By kc on 01/11/2013 13:08:20 Quote Link to comment Share on other sites More sharing options...
Bearair Posted November 1, 2013 Author Share Posted November 1, 2013 Thanks all my issue is that the model has the bulkhead glassed in so I dont wont to move it. I have 3 7/8" space to work with. So Iif I use a modern 60 it will not fit, hence im hoping this Rossi which has never run will give enough power. From the web I know it will turn a 11/5 at 16000rpm opinions gratefully acepted. Quote Link to comment Share on other sites More sharing options...
Martyn K Posted November 1, 2013 Share Posted November 1, 2013 mmmm. 16k rpm will sound lovely and will certainly get it off the ground OK. I would imagine that it will accelerate like a scalded cat with a 5" pitch prop. Suck it and see, it wont be a million miles out. Martyn Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted November 1, 2013 Share Posted November 1, 2013 As I say I really can't see there being a problem with power Roger. The Rossi is spec'ed to produce over 2hp at full revs - that's a lot of "go" for a 53! If your weight estimate is correct then its over 300W per lb - that's a very high power to weight ratio - unlimited verticals sort of power! BEB Quote Link to comment Share on other sites More sharing options...
Bearair Posted November 1, 2013 Author Share Posted November 1, 2013 Thanks, Martin and BEB for the reassurance I am going to give it ago. My experience of Rossi's is that they run great flat out or at ideal its just the bit in the middle they are not so clever at typical italian engines in my experience (Laverda's more than anything). Its also the way I used to see aerobatics flown at the time the Birdy was competitive. Roger Quote Link to comment Share on other sites More sharing options...
Bill Michie Posted November 3, 2013 Share Posted November 3, 2013 You'll definitely want more pitch............... 5" pitch will give rapid acceleration, but not to the speed needed to fly these models. My DB 60 (GP ARF) runs a fairly old ST .61 on a pipe, turning an APC 11x8 at something like 14K. And it's ballistic. So I'd suggest you need 7-8ins pitch to get the practical top speed. IMHO, the "2 BHP" figure is just a number, esp at some unattainable rpm; what you need is an engine/pipe/prop combo that'll give useful rpm & thrust to give the speed, on what will still probably be a 7-8lb aeroplane. So I'd start with an 11x7 or x8 (probably too much initially) & pipe to suit.................. Bill Quote Link to comment Share on other sites More sharing options...
Bearair Posted November 3, 2013 Author Share Posted November 3, 2013 Well here she is ready for strip down and sanding, shes fitted with retracts and is basically sound. The anhedral tail interests me because none of the birdies I've seen had on. Maybe tge original builder was looking to follow the fashion. Quote Link to comment Share on other sites More sharing options...
Martyn K Posted November 3, 2013 Share Posted November 3, 2013 Nice colour scheme Roger... I would also go with Bill's advice regarding prop recommendations, he is far more knowledgeable about these matters than I am. Martyn Quote Link to comment Share on other sites More sharing options...
Bearair Posted November 3, 2013 Author Share Posted November 3, 2013 What I think I will do is start off with a 11 7 as Bill suggest's but with a mini pipe rather than trying to get the motor and pipe sorted together. It's going to be a lot of trial and error but hopefully will be worth it in the end. Roger Quote Link to comment Share on other sites More sharing options...
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