The OS NVA set to give around 10,300 at take off , just breaking near a 2-stroke. After a couple of laps you can clearly hear it returning to a full 4-stroke with the revs' reduced.

  If I understand correctly, that's about what all of mine do. The reduced load makes it more likely to misfire on alternate strokes, so further into a 4-stroke. A Fox 35 will be almost a solid 2 on the the ground, and then after about two laps be a solid 4.

   Brett

  If I understand correctly, that's about what all of mine do. The reduced load makes it more likely to misfire on alternate strokes, so further into a 4-stroke. A Fox 35 will be almost a solid 2 on the the ground, and then after about two laps be a solid 4.

   Brett

Brett thanks for that.

I posted this thread as this is the only engine I use which has richened after take off.

I'm using TT36's , Magnum 36's , LA46's , Tom Dixon mod'd ST51 and FP 35 for example.
Non of them changes tune after launching.They all hold the needle setting.

I'm going to experiment with other props' as suggested .

Thanks for your comments.

Robin.

Kim , thanks for your contribution.

As regards fuel , I bought 5 gallons of 'straight' [ 80 / 20 all castor ]  FAI fuel recently at a very good price .

Over here 5 litres of fuel costs from around 29 Euros .....Don't know how many 'bucks' that is , sorry.

We also have to travel quite a way to get to a Model Shop. Delivery using one of the Mail Order operators adds another 12 euros to the cost as it cannot go by post , but by a carrier . [ flammable material ] .

I havn't noticed any problems setting the needle at all. I did add some synthetic to the fuel to take the overall lube' content to 23% .

I do think my problem is tank related.

Robin.

ps We're in SW France , just NE of Bordeaux. The beautiful crowd are down on the coast , St. Tropez etc. Car parks full of Ferraris , Masers , Jags and Porsches ! I remember it in '68. Just a sleepy village then.Too rich for me now.

HI Robin,

I don't know nearly as much as Brett or Randy, but I see the exact same thing.  In fact I worry if certain engines DON'T do it!  About 1/2 lap to a full lap and the engines settle into a full 4 cycle if the needle setting is correct......  about the only ones that don't do this are OS 20 FPs set up in the Brett set up or other low pitch high rpm set ups which will still richen up slightly.  All my other "stunt" engines (PAs, Aero Tiger 36s, ST .51s, etc.,) will pretty much do it if set correctly and "propped" correctly.

My understanding (as explained by the aforementioned) is that when the model is waiting for release the engine is "loaded", but unloads somewhat once the model is flying.

Big Bear