CL with an OS .15FP @ 7000 ft altitude..

My grandson's Akromaster is not the greatest design and the ship may be a tad heavy after the repair job, but even before that it was hard to get a loop out of it with an APC 8-4 prop (or 8-5).
[photo not recovered: 40095.jpg]
In the crash I destroyed the GRW2000U (2 Oz snub nose uniflow) and replaced it with a Sullivan 2 Oz clunk tank; Dan Rutherford should be proud of my taking the plunge. Besides, I saved $7.00 on the tank and the sullivan works well in "Rutherford mode" venting.
Also, just as important, the clunk tank is about .6 Oz lighter.
Today I had a friend open up the venturi to .242 (I'm using a ST .51 NVA); we'll see how it goes. I'm using 15% nitro Omega.
A store in Albuquerque called "Big Boys Toys" is selling of his RC gas planes (mostly ARF's) for lss than half price because he is only going to have electric. This is probably because the high nitro fuel is getting pricey.
What else can I do ?

PS : Omega is a Morgan fuel product. Gal container does not state the amount of oil, only "castor/synthetic mix". I presume it's 18% and I should add about 1 Oz of castor to the quart.

Attachment #1, (jpg file)

Opening the venturi should help immensely. The stock needle is a .125 diameter. The ST needle is .155. You choked off most of the power. It is like running at about a quarter throttle with the stock venturi (I didn't calculate it, but it is bad). So opening it up will give you back the power you should have had to begin with.

Now, as to looping, I began life with a Testor's Sophomore with a McCoy .10 on it. And it was HEAVY (Yes, I know, I am shouting). I could still do a loop with it--very poorly, I might add, but I could do one. So with a proper venturi and all it should be capable.

I moved up to Ringmasters and Sterling Yak and Mustangs with a K&B 35 on and never looked back. When Matt started out we built him a small profile with an OS .20. I would fly mine, he would fly his, back and forth. One day I let him fly mine. The .20 was shelved from that day forward. When you have enough power to pull the plane, give you line tension, and fight the wind flying becomes far more pleasant. (Of course, the bigger planes take more fuel and are more prone to breaking in a crash, but that is the price one pays.)

Let us know how the new venturi turns out.

I've flown at Albuquerque quite a bit. It's a tough place to fly. The above post give good, no, great advice but the plane still may not be up to it. A plane with a bigger wing and more capable engine should solve that.
I think Omega is 17% lube. As a rough rule, it takes 1.3 ounces of castor oil to increase the oil content of a gallon of fuel 1 percent. I'd increase it by 5% to about 22% which would take about 6.5 ounces. I'm going to assume you are in contact with Jim Snelson of Control Line Central in Corrales and the Albuquerque C/L club. Jim's shop specializes in C/L and the club is very active.

...edited for oil content per post below...my bad, thanks!

Of course you mean 1.3 ounces per gallon increases the oil by 1%. I've seen that castor/synthetic blend and I have to believe it has a minimum of castor in it. I agree add 6.5 oz of castor but don't use the castors you get in motorcycle shops ect like Blendzal it will turn your fuel to crap. Call S&W fuels for the right ingredients.


MM

I doubt that Leonard has experience flying CL at 7,000'. I admit to that, myself. But I did try flying at 4,950' with Larry Richards in Spark/Reno, and quickly decided that it wasn't for me. HUGE hit on the performance of the plane, even if you can make up for the power loss with more Vitamin N and bigger venturi. [photo not recovered: shocked.gif] Steve

Steve Helmick
Renton, Washington
USA

Steve,

It looks like my grandson is going to live in Albuquerque for quite some time, so I need to come up with a .15 plane for him to learn on.

I flew a Skyray 35 here once with an OS .25 FP and it was a bit sluggish, but could do loops and lousy wingovers.

This winter I think I'll build an Aldrich Peacemaker for him and
add one bay to each wing. I would, of course, give up my tradition of covering my planes with silk. I prefer silk for a beginner because it makes the wing so strong. I'd probably go with polyspan.

Rex

Hi Rex I wuold build another Skyray 35 and put a la 40 or 46 on it for the altitude problem of power should not be a problem