jayseas

Looking to see if anyone can tell me the difference between these two models of Fox .15. In performance mainly. One has the slant plug and one has the straight up.

http://cgi.ebay.com/U-CONTROL-AIRPLA...DLVI%26ps%3D54


http://cgi.ebay.com/ws/eBayISAPI.dll...m=160340680105

icerinkdad

The first engine is the older one and I have never owned one. The second engine with the slanted plug is fairly high performance for a cross flow scavanged engine and somewhat lighter dueto it having a steel drop in sleeve instead of the entire top endof the motor being steel. They run best on a fairly small prop, maybe a 7-5 or 7-6,and fuel with 15% or even 25% nitro.Do not expect them to have the classic "stunt engine run" of the Fox 35or to like running onlarger props.We used to use them to fly Goodyear before the imported engines took over. They are light weight (probably lighter than the first engine). Shoot have just about talked myself into bidding on it. BTW they are nearly the perfect engine for a plane like the SIG Akromaster or the SIG all sheet Goodyear models. Oh, and theyMUSTbe run on fuel with at least 20% castor oil or they will have connecting rod and piston wear problems.
Bob

jayseas

Thanks Bob, for your response, I have two of the slant plug fox .15 and they do run really well, i was just wondering on the older one with the straight plug if they ran as well as the slant plug.I've running it on sig 15 % but i have been addding castor to the fuel, so far so good.I have been useing a 8x4 and it runs well, maybe i will pickup a 7x6 and try that and see how she flys.
Jim</p>

icerinkdad

Make it a 7-5 and I think you will be surprized at the power that little old engine has.
Bob

gcb

jayseas,

The "steel fin" version came out in 1958. I have one I bought new back then. I did not use it much because performance was not what I expected. I was using an 8x6 prop. When I dropped down to an 8x4, it ran great. Duke Fox recommended using an 8x4 or 7x6. Play around in that range to see what's best for your setup but, as Bob said, don't over-prop it.

The slant plug is also known as the 15X. It was released a couple of years after the "steel fin". The one you referenced appears to be the first iteration with no provision for muffler. Subsequent versions had a shiney case. Same props for both.

George

jayseas

I have two of the slant plug version, one shinny case the other is not, the one with the shinny case reaaly screams the other runs good but not like the shinny one both feel the same on compression. will try the 7x6 prop.But the shinny one screams with the 8x4.Will see.

Jim Thomerson

Look at the Fox 15 post a few topics down.  Some good information there.