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New sonerai one owner.

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Razor

Well-Known Member
Joined
Sep 2, 2013
Messages
49
Location
San Antonio TX
Hello all I have just purchased a Sonerai 1. It is in near complete build and only needs stew things to get it going and inspected. It has a 1600 cc engine and I am just now working out the bugs on the stromberg carb trying to get the RPM for static to fly. I'm only getting 2850 static on run up. Is this sufficient for a 1600 cc that weighs 520 lbs with a 3000' paved runway? I've already talk to some of you and all the help and info is greatly apreaciated!
 
Razor, 3000 feet of runway is plenty, especially if you have good approaches.. 3000 rpm static, I recall, is what my last test prop would do with a 1600 engine, but the memory has faded quite a bit….Ed
 
Thank you race air! I have been getting a lot of different answers for the static at run up. One has mentioned 3500 static with 3600-3800 cruise and I believe another has mentioned 3100. I just want to make sure that I have enough to get the plane on a decent climb without causing any issues stalling.
What should cruise rpm be?

I figured I would see cruise around 3500-3700 rpm and climb about 3200. Does this sound about right?
When I get the plane moving I should gain some rpm on the prop bite. So are you suggesting that I see 3000 rpm sitting still?
Thanks for the reply! I'll be sharing photos soon!
 
Raceair said:
Razor, 3000 feet of runway is plenty, especially if you have good approaches.. 3000 rpm static, I recall, is what my last test prop would do with a 1600 engine, but the memory has faded quite a bit….Ed

Did your plane fly at this rpm of static and if so what did you see in cruise mph and rpm?
 
I would say that 3000 RPM static (sitting still) with the 1600 engine is a minimum. I would think that 3200 static is closer to the norm, and would feel more comfortable seeing 3200-3300 on the ground. Yes, Inflow changes the number dramatically. I believe in cruising VW engines at about 3600 rpm. There are many people on this forum with much more recent experience than me. VW engines, being relatively short stroke engines, develop their peak power with RPM…The winning Formula Vees of the day were seeing 4200 rpm full throttle with a 48 inch diameter prop……Ed
 
Prim,
I did see that sticky and the issue there is that I only saw one guy that has a 1600 engine and he posted cruise rpm nothing about static. Maybe I missed something. I going to try to shoot for 31-3200 rpm.
And suggestions on if I should send the prop back for pitch change or lesson the diameter myself? Ate there any pros or cons?
 
Thanks for the reply. I will have to measure the diameter of my prop and see if that needs to be changed. How hard is it to ballance after you cut yours down? I've done untraligts before and had a ball enter for those rotax props but not for the vw prop.
I saw your modification on the post and will surely try to get the static up. I did run it without the filter on and the carb is a ugly thing which I plan on cleaning up and customizing the cowl for a cleaner more efficient look. I'll try the run up without it! I'm sure that will help. The filter is a very cheap lawn mower filter wich is very restrictive. It has a carb heat flap which is not hooked up. I can use the filter for taxi and open it for takeoff and cruise. I would actually like to make the carb a ram air with forced induction cowl close to the prop. The stromberg carb is nice but ugly!

juergen said:
Hi Wes,
I have completed my old message:
http://www.sonerai.net/smf/index.php?topic=50.msg21195#msg21195

I have seen on the picture, you have a air-filter on the carb... have you tested the rpms without filter?
With this small engine, you need all the power you can activate!

with best regards
Juergen
 
Well today I had a chance to get the manufacture name and measure the length of the prop. It was 52" long so I assume I have plenty to cut off? What are guys normally seeing in length and pitch?
Can anyone give me pointers on how to cut and ballance the prop correctly? Any trick I shoud know of like chamfering the edge and reshaping the tip? Anybody try molding a Q tip on the end for a added benefit?
 
Im getting 3300 static rpm and in cruise i use 3200 rpm, 5gph burn and indicating 145 mph.
 
If your prop is already at 52" diameter, you really don't have plenty available to cut off……The strict Racers were at 48" diameter, but they had higher compression ratios and lots of pitch….When trimming props, 1/2" diameter at a time will see changes in performance….
 
BoeingPilot said:
Im getting 3300 static rpm and in cruise i use 3200 rpm, 5gph burn and indicating 145 mph.

Thanks Boeing pilot can you tell me what pitch and length prop you had? At 3300 rpm static what climb did you see in performance?
 
Raceair said:
If your prop is already at 52" diameter, you really don't have plenty available to cut off……The strict Racers were at 48" diameter, but they had higher compression ratios and lots of pitch….When trimming props, 1/2" diameter at a time will see changes in performance….

Thanks race air I will try 1/2" at a time to get to at least 3300 rpm.
 
Remember, the engine is a 1600 c.c. What other people are flying with a 2180, or even an 1834 might not be the same….
 
Razor , What I was saying is that I think BoeingPilot is using a bigger engine, maybe a 2180…The recommendations on prop size must come from people whom are using your same engine size. Anything I refer to on the airplane is based on my experience with the 1600c.c. engine, nothing any bigger.
 
Here is an article on re-pitching props. The idea is to increase static rpm by reducing pitch at the tip, but not reducing the diameter. I tried this on a 54" prop on 2180 VW. The static rpm increased and climb performance was improved a bunch.
 

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