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PostPosted: Mon Aug 13, 2007 10:46 am
by lazairkid
Hi guys,
I have some engine numbers for you on my Solo 210 .
At 15Hp 1,8 to 1 redrive and a 44x22 prince p-tip props
At 95 degrees out side with dens alt of 2200ft. Man it's been HOT down here in S.C.
I get a static thrust of 100lb each engine at 5150 rpm's. That's 200 lb total
That's not bad. My friend has a 2xcarb Rotax 503 and was getting 222lb of thrust
and his flightstar is a two seat.
I may even be able to do better than that with some more tuning of the carbs
and lower weather temps.
I have not got off the ground yet, the weather has not cooperated. We have had
temps ner or in the 100's and t-storms just about every night here with winds of 15 or more.
Lazairkid B)

PostPosted: Mon Aug 13, 2007 8:51 pm
by daffy1029
Hi lazairkid,
WOW!! How did you measure your thrust? Were you up against a wall? With JPX engines we get 85lbs+ thrust each in a open field at 2500 ft above sea level at about 75 degrees F. We used a fish scale to measure the thrust. I get about 75-80 lbs of thrust (at best) with my Solo's at about 6000 rpm with 2.5:1 ratio. 44" prop and I think the pitch is around 26- 28. I would have to check on that to be sure. So if you are getting that much thrust, that's really cool! You will get even more power and thrust in cooler weather for sure! That is awesome!

Also do you have any bubbles in your fuel line at high revs? I have tried everthing and just could not get rid of the bubbles in my line. Maybe it's because of the higher revs that I am running at? So, I came up with an idea and I mounted two small tanks (24 oz each), one behind each engine on the nacelles. The tanks are just higher than the carbs, so that when the tanks are full, they siphon down to the carbs. I added a mikuni pump and tee'd it into the same vacuum line that goes from the engine to the carb's fuel pump. I also kept this vacuum line below 10' long for best performance. The mikuni pump now pumps fuel up to the small tanks (bubbles included). When the small tanks are full, there is an overflow line that goes back to the main tank. So the mikuni pumps keep the small tanks full as long as the engines are running. The small tanks act as a bubble baffle (or bubble killer). Now I get no bubbles whatsoever! The engines are running strong and steady now. Seems like a complex system, but it works! I flew last Sat and it worked perfectly!

Just a note; I had these small tanks just lower than the carbs when I first tried it, and still got bubbles. I just could not believe this would happen, so close to the engines. So for the heck of it, I raised the tank and discovered that the bubbles disappeared. The rest is history. Daffy :D

PostPosted: Tue Aug 14, 2007 8:27 pm
by lazairkid
B) Hey Daffy.
The scale was more for deer and thing, I think it went up to 400lb or so.
We hooked the other end to a steal beam holding up one of your new hangers.
I was surprised to with the reading of 100lb per engine, but that is what my
friends side it was.
The new engine mounts are holding up good, I think these will work.
I got a pic of them, noticed the bottom mount, there are two tube's this times
so this should hold.
About air bubbles, ya I get them in the beginning but they go away after
about 2-3 min, they seem to start half way up the wing when the engine is
shaking the most.
I did some fast taxing tonight, got up to about 15mph, did good until the 3rd
run down the grass strip when I ground looped, not bad the wheels did not
come off the ground, It did get my attention. I don't know how the guys in the
series I did it with the short landing gear.
Lazairkid :blink:

PostPosted: Tue Aug 14, 2007 8:28 pm
by lazairkid
number two

PostPosted: Tue Aug 14, 2007 9:22 pm
by daffy1029
Hi lazairkid,
Your set-up looks real good! The plane looks great! I will be waiting to hear about your first flight! :) Daffy

PostPosted: Wed Oct 10, 2007 9:01 pm
by daffy1029
Hi lazairkid,
Sure looks like your lazair, that you are trying to sell?! How come you are selling it so soon? Did you get in anymore flights?
I just about have the bubbles in fuel line problem licked. I will be installing some small buffer tanks (aluminium) higher than the carb and creating a positive flow to the engine carbs. Trying it out this weekend. Daffy

PostPosted: Thu Oct 11, 2007 10:39 am
by lazairkid
Hey Daffy,
Yes it's mine.
I have got some 1000 foot hops in but no real flight time.
I'm looking for something else to fly and there is no room for two planes in my
The guys here jump in there planes every weekend and go places and I'm
left behind working on the engines trying to get them right.
You asked about Bing carbs in past post.
I tried them to but the engines shakes the float bowl to much and that makes
the carbs flood out.
I'm fixing to put walbre 32's on and try them. I had 37's on before and I was
getting 100 lb trust on left engine and the right engine drops to 75lb.
I'm trying to determine if it's the engine or carb.

PostPosted: Thu Oct 11, 2007 11:27 am
by JPXman
i had a theory about the solo 210 installation, and after seeing your pictures it might still hold true:

the solo is used mainly in a pusher configuration - there isn't a high speed flow of air in the vicinity of the carb as such. with the tractor configuration, there is a blast of air that goes right by the carb.

on the 185, it uses a velocity stack (or trumpet for bike folks) with a bell mouth at the end (flared almost to a flange). in fluid dynamics, this bell mouth means that if you put a jet of air over the opening, it would NOT act like a spray bottle and create a vacuum inside the trumpet - it provides a neutral pressure zone at the opening as if there was no flow there at all.

everyone knows that if you are drinking a fountain pop out of a cup with a straw, and you blow over the end of the straw horizontally, that the pop will rise up in the straw due to the suction that the airflow creates inside the straw.

well, with these solo 210's and having just a carb filter over the intake of the carb instead of a bell mouth opening, and the prop blast going right over the carb, i'll bet that the prop blast is interfering with the normal pressures the carb is used to on the intake in the tractor configuration. i haven't seen one other solo (or rotax 185) installation that uses this engine in the tractor configuration. and if there was one, i'll bet the carb is faired from the prop blast somehow.

on daffy's solo's, his carb filter is soaked with gas on the backside of the filter but is dry on the front side.

its just a theory, but like always i'm full of them. to see if it makes a difference, perhaps place a fairing over the carb on the front side, or some kind of air filter housing like on a car that would ram the prop blast into the carb for a "boost" :)


PostPosted: Thu Oct 11, 2007 3:01 pm
by lazairkid
If this is true could you not place a aluminum plate say of .016 over the back half of the filter
That would trap the air and force it in to the carb instead of going threw
the filter making the vacuum.

Theory's are how problems are solved!!!

PostPosted: Thu Oct 11, 2007 11:28 pm
by JPXman
but that would make carb tuning dependent on RPM...........high rpms you have high airflow so you need way more gas. low RPM you need way LESS gas.....

you should fair the front of the filter, so that the filter only intakes turbulent air from the backside which is usually at constant pressure. This is how the carb on the JPX works, and it works well.