Engine for Flair SE5A

[Ashley Hunt]

While on the subject of props then, I also have a Puppeteer which has an old Laser .61 engine in it. I’ve been running that on a 12X7 prop but I’ve never felt completely happy with the way the model flies. 

[Paul De Tourtoulon]

1 hour ago, Ashley Hunt said:

While on the subject of props then, I also have a Puppeteer which has an old Laser .61 engine in it. I’ve been running that on a 12X7 prop but I’ve never felt completely happy with the way the model flies. 

Maybe a 13 x 6 or better still a 14 x 5 ?.

[Jon H]

1 hour ago, Ashley Hunt said:

While on the subject of props then, I also have a Puppeteer which has an old Laser .61 engine in it. I’ve been running that on a 12X7 prop but I’ve never felt completely happy with the way the model flies. 

 

Paul has more or less nailed it. 13x6, 14x5 and even 15x5 would be fine

[Frank Skilbeck]

Years ago I had a biplane a bit larger than the Flair Se5a, it was initially powered by a Webra Speed 40 with a 10 x 6 screaming away, it was slow to take off, as I also had an OS 40 FS (the very first type), I change the prop on the Webra to a Graupner 12 x5, the model flew much better but the webra wasn't happy on that prop so I put the OS40FS in it and it flew like that until a flat receiver battery caused the models demise a couple of years later. Still got the OS40FS and it's in a mates Junior 60 pottering around at 30% throttle.

[Ashley Hunt]

Thanks for all the replies. It’s been really useful. 

[Matt Carlton]

23 hours ago, Ashley Hunt said:

All the information on props was great, that’s always been a bit of a black art for me and just buying different sizes to see what happens can get expensive, so thanks. 

 

Regardless of whether you stick with the engine you have or change it to another, it will always be worth exploring different props and matching them to the airframe. The effects can be quite dramatic and transformative. Well worth the cost imho.

 

Too many people have decided a model "flies badly" and given up on it, when in fact, some tweaks to prop size, cg, control throws etc could totally transform it. 

 

Recommendations (prop size, cg, control throws and so on) are a starting point, not an end point. 

 

Fly, note, tweak, repeat. 

 

Standard practice in Free Flight and something I think we could apply much more in RC than we typically do. 

 

 

 

 

 

[Engine Doctor]

As per Matt Carlton 👍.  Building,flying and trimming freeflight models was like an apprenticeship in modeling .

Only change one thing at a time though  when tweaking a model and test fly it . For instance if its wing incidence problem then make a temporary adjustment by packing wings with some thin sheet balsa until your happy with results then make it a permanent modification even you get home. 

A friend of mine asked me why his Fokker D8 didn't fly vert well . It was or8ginally  designed as a free flight model and had been converted to rc. We discussed some tweaks and the last thing I said to him was "do one thing at a time and test fly" . He didn't,  he changed side thrust and down thrust of engine, wing incidence and CoG . Then test flew it. Result a write off. 

So many models of the ARTF models now fcome with very misleading instructions regarding setting up control throws. If set up as instructed they fly at best badly and at worst uncontrollably. If your not sure then ask around and get views and set up from other pilots of similar models.

Edited July 16, 2022 by Engine Doctor

[Jon H]

I absolutely agree that small changes make a huge difference. The right prop can transform the performance of a model. The same prop from different brands can vary massively in performance. 

 

Rates too are a big one and today i took 5% off the ailerons on my sea fury and suddenly lost all confidence in it. The thing just didnt seem as solid as it used to be 

[Trevor Crook]

Another vote here for the O.S. 40 Surpass - The SE5A I had about 30 years ago flew just fine on that, with, I think, an 11x7 prop. If you've got the engine already it's worth putting it in and seeing how you get on, it will certainly fly. As Jon says, getting an alternative is quite an outlay.

 

I sold my SE5A about 20 years ago, and regretted it, so about 10 years ago my father in law built me a new one from the plan which I'd kept, for an electric power train. It flies the same as the old one, unsurprisingly!