Richard,
I find that is how I get started on a new project, too. One piece catches my attention and before I know it, I am collecting parts that "match the first piece I got." Like a Cosmic Wind project that started with a really nice 1/2A spinner.....
I run all of my 1/2A stuff on either 25% or 35% nitro mix. It keeps the number of different types down to something manageable. Works good for me on everything from 1/2A flight trainers on reed valve engines up thru Mouse racers, with Medallion and TD motors somewhere in the middle. Low nitro (less than 15%) just makes them harder to start. Be sure your mix has a fair amount of castor in it, but remember that all-castor will tend to varnish up Cox engines and the higher fuel viscosity will make fuel feed on a TD (more) marginal. The only reasons I would go on the low end for nitro is cost, or if I had a marginal tank volume. Run time goes up when nitro percentage goes down. If you get backed into that corner, use a primer bottle with 35% in it, and your life will get easier.
I have tried using a TD on a stunt plane and it did ok, but was finicky with regard to tank position, fuel line diameter, use of timed pressure, and the phase of the moon. The Medallion is more tractable in my opinion, probably mostly due to the different venturi and needle arrangement. I would not bother with the timed pressure port on the side of the inlet housing. That did not work well for me the few times I tried it. Rear crankcase pressure (a la Joe Klause modified backplate) works like any other case pressure system. If you can deal with the pinch-off and routines to avoid flooding, it works fine once running. I am not a fan of in-line check valves on the case pressure line. Too many have gotten stuck or leaked for it to seem worthwhile to me. Therefore, having access to the pressure line would be mandatory in my view. On a full-body plane, you need to bring it out and then route it back in. This line does not need to be large, as the viscosity of air is tiny in comparison to the standard small tubing diameter, the length needed, and miniscule air flow rate. Make an arrangement that is easy to squeeze shut with the hand you normally hold the model when starting.
I would be prepared to experiment a bit. Personally, I would start out trying suction feed. I likely would go down in venturi diameter to improve fuel draw and reduce the power some.
If you are not using the timed pressure port, then make sure it is sealed. On a used engine, someone may have already drilled it out.
I have a Pinto to build one of these days. I think it is a very pretty design, and there are some nice ones around, for sure. My kit was pretty old, and some of the hardware was pretty rusty. I thought some of it was larger/heavier/more rugged than it needed to be, so I will probably down-size some of it. I didn't see much else I couldn't live with just the way it was.
By the way--nice wheels!
Dave
Topic: Pinto 1/2 a (Read 2106 times)