engines

Share your thoughts, photos and general help to all builders

Postby ozzie » Fri Nov 05, 2004 2:30 am

saw this whilst in italy. a small go kart engine water cooled, small belt drives water pump, reduction drive. fitted to a paraglider back pack this one is around 100 cc but also has a bigger brother. has about 500hrs runs hard but starting to sound tired. don't know if the redrive could handle the load from a tractor setup. 45lbs thrust.[SIZE=1]
You do not have the required permissions to view the files attached to this post.
BLUE SKIES AND FULL TANKS
User avatar
ozzie
LazairNUT
 
Posts: 403
Joined: Fri Jan 16, 2004 4:56 pm
Location: australia

Postby Chappy » Sat Nov 06, 2004 12:32 am

Steve,

As a comparison (just for fun), the 99cc Pioneer P61s turning around 8000rpm, with my homemade pine props and V-belt re-drives, and straight pipes can produce a peak static thrust of 65 pounds each. With dual Briggs and Stratton lawn mower mufflers (my current setup), they make ten pounds less each. On the down side, though, 200 hours is about all they can make before being all used up!

I guess that net they have to use for protection from the prop really hurts the thrust, and the penalty must get even worse as their airspeed increases.

Oz, great picture, but how about using a camera next time instead of a microscope!

HeHeHe

Chappy
Chappy
LazairNUT
 
Posts: 330
Joined: Wed Jan 28, 2004 9:57 pm
Location: Northern Virginia, USA

Postby daffy1029 » Sat Nov 06, 2004 11:29 am

hi, y'all
Are we still talking 2-stroke here? A water-cooled 2-stroke should last much longer and usually they put out more power. For example a stock air-cooled engine in a snowmobile and a stock water-cooled engine of the same size, it seems the water cooled sleds out perform the air-cooled in drags and lasting ability. The air-cooled sleds can sometimes perform better in deep snow because of their lighter weight (if they don't overheat). You can push a water-cooled engine a littler harder as well because it is reluctant to overheat . Just my two cents worth.

Chappy, how are parts to get for your Pioneer engines? What does it cost to rebuild a Pioneer completely? I would think they would be economical to rebuild.
By the way, I just finished testing one of my old JPX engine and the thrust I got was 80 lbs. direct drive at 4200 rpm(2500ft above sea level), using 34 x 20 pitch prop. These are rated 20 HP. So your 5.5 HP Pioneers are really impressive at 65 lbs thrust. Well done!
Daffy
daffy1029
LazairNUT
 
Posts: 168
Joined: Sat Feb 21, 2004 12:17 am

Postby Chappy » Sat Nov 06, 2004 10:42 pm

Daffy,

There don't seem to be a whole lot of rebuild parts still available for the little Pioneers. They may be out there somewhere, as some places seem to have a cylinder, another place pistons and rings. I don't think I've come across a crank in a long time.

Anyway, I've never rebuilt one, just cleaned them up now and then, and maybe a seal and/or bearing. Mostly it's just carb rebuilds and plugs.

Because so many early Lazair owners upgraded to the 185 Rotaxes, for a time there were lots of low time Pioneers floating around, and I was given several pairs way back then (Dale and Peter Corley gave me at least two sets). I still have one good, unmodified set for my next replacement. The biggest mod I have to make to the engines before I can use them is to machine the second side of the crankcase flat and drill through the crankcase at each of the clamp screws. Long AN3 bolt then clamp the crankcase together between the two re-drive plates. The starter assemble is removed and mounted back on the original side on a homemade bracket. A homemade sheave is mounted on the power takeoff end of the crank.

If you just hold the engine in your hand and look at the small physical size of its components, you begin to realize why the engines don't last very long. The engine itself only weighs around six pounds. As a chainsaw, you wouldn't hold 6500-8500rpm for very long periods - mostly fairly short blasts of full power. 200 hours at these continuous high rpm/power levels would probably equal cutting up a whole bunch of trees, I would think.

I've found that if I run them fairly rich, I lose a little performance, but the engines run so much cooler that they hold up quite a bit longer. With the mixture leaned for maximum power, the cylinder head temps can run way up there at 450+ degrees F (yet I've never had a piston or ring failure). The most severe failure I've experienced was on a high time engine when the PTO end crank bearing shell started spinning inside the crankcase. The bearing overheated and the ball separator melted, permitting the balls to try to bunch up, causing the engine to abruptly lock up. Boy, did the belts let out a screech.

A slow turning, long prop is much more efficient (and quieter) than a smaller, directly driven prop. I put a lot of work into designing and building very efficient props, and they are very lightly loaded. Along with the 2.75:1 reduction and running the engines at maximum power, they do surprisingly well (for a while, anyway). BTW, the Pioneer only produces around 4.5 horse power or so when running direct drive props! Find a power output to rpm chart for your engines, find your rpm with your direct driven props, read their actual power output, and weep.

Chappy
Chappy
LazairNUT
 
Posts: 330
Joined: Wed Jan 28, 2004 9:57 pm
Location: Northern Virginia, USA

Postby Guest » Sun Nov 07, 2004 10:57 am

daffy1029 @ Nov 6 2004, 11:29 AM wrote: hi, y'all
Are we still talking 2-stroke here? A water-cooled 2-stroke should last much longer and usually they put out more power. For example a stock air-cooled engine in a snowmobile and a stock water-cooled engine of the same size, it seems the water cooled sleds out perform the air-cooled in drags and lasting ability. The air-cooled sleds can sometimes perform better in deep snow because of their lighter weight (if they don't overheat). You can push a water-cooled engine a littler harder as well because it is reluctant to overheat . Just my two cents worth.

Chappy, how are parts to get for your Pioneer engines? What does it cost to rebuild a Pioneer completely? I would think they would be economical to rebuild.
By the way, I just finished testing one of my old JPX engine and the thrust I got was 80 lbs. direct drive at 4200 rpm(2500ft above sea level), using 34 x 20 pitch prop. These are rated 20 HP. So your 5.5 HP Pioneers are really impressive at 65 lbs thrust. Well done!
Daffy


Hmmm, I wonder how good a Solo 210 engine would work direct drive. According to FLY Paramotor their Power 70 model with direct drive Solo puts out around 35kg (~77lbs) of thrust. This engine weighs a little less than a Rotax 9.5 while producing nearly the thrust of a 40lb+ JPX engine ??? What am I missing here ? Why wouldn't this be a good arrangement ?

Those water cooled engines look great. I think the problem is they weigh in the 60lb range. That weight may be too much for Lazairs.

Anyone looked at the Easy 100 engine ?
Guest
 

Postby daffy1029 » Sun Nov 07, 2004 2:26 pm

Guest,
Solo's engines (from the research I've done) are very good engines except in a direct drive configuration, because the ball bearings in the engine aren't designed for thrust. I read that someone had done this and has to replace the bearings about every 50-100 hours. But in a redrive situation where there is no thrust whatsoever, makes it ideal for this application.
I have aquired two for my Lazair and now in the process of making mounts with a 2.5:1 reduction for the nacelles. The engines I bought were off the Adventure F-series paramotor gliders. I am keeping these engines stock and are suppose to put out about 14 HP. So with a 44" diameter prop at about a 22 pitch should give me about 100-120 lbs static thrust. The JPX"S I have now are putting out 80-85 lbs thrust in direct drive configuration. More to come after I fix my car...
Daffy :)
daffy1029
LazairNUT
 
Posts: 168
Joined: Sat Feb 21, 2004 12:17 am

Postby Guest » Sun Nov 07, 2004 3:04 pm

You mean to tell me Fly Products is selling direct drive Solo 210 backpack motor units that needs complete rebuild every 50-100 hours ??? Sorry, I'm not totally convinced this is entirely the case based on ONE persons reported problems. Can you give an address to web-site contaning this information. Looking at the schematic drawings of the 210 it appears to have a beefier crank and bearings than that of the Rotax 9.5 ??? The engines are also fairly cheap new.

Maybe I'm not aware of the optimal set-up for engines on a Lazair but didn't the company use direct drive engines as standard equipment on every model of the plane they produced. Thinking about it objectively then why weren't redives used on the existing engines to increase thrust ? When Lazairs needed more power a higher HP direct drive engine was adopted each time apparently. Another question is why would the single seat Lazair would need over 100-120lbslbs thrust per-engine when the JPX engines direct drive at 80lb thrust was all required to power the two seater plane. Seems to me that 14-18 hp run direct drive would be more "Ideal" on a single seat Lazair.
Guest
 

Postby Chappy » Sun Nov 07, 2004 4:13 pm

I've never heard of any serious problems running the Solo 210's direct drive. On the other had, there were problems on early Rotax 185's. Ultraflight had a series II factory demo plane fitted with 210's in 1983 for evaluation when I worked there. I can tell you that they produced a very noticeable boost in rate of climb over a Rotax 185 (when both were fitted with the stacked factory props), because I flew both on the same planes. They also built and flew re-drives on both the Rotax and Solo engines that year.

Ultraflight used the Rotax engines because they were much more suitable, powerful, and long lived than converted chainsaw engines, less expensive, and locally available. The Solo was not locally available, and would have cost the factory more. This is an important point, because even with the smaller engines used on a Lazair, compared to other popular Ultralights, it used TWO. That, and the choice of materials and complexity made the Lazair more costly to produce than most of its competitors.

Lastly, and most importantly, Dale Kramer (who designed the Lazair and owned the company), had a personal bias against reduction drives. He much preferred the simplicity and weight savings of direct drive. Very few belt or gear reduction type re-drives of the early 80's were all that trouble free anyway. He continued to investigate larger engines running direct drive props, because that's what he felt was a better way to go.

Chappy
Chappy
LazairNUT
 
Posts: 330
Joined: Wed Jan 28, 2004 9:57 pm
Location: Northern Virginia, USA

Postby Guest » Sun Nov 07, 2004 10:14 pm

Chappy @ Nov 7 2004, 04:13 PM wrote: I've never heard of any serious problems running the Solo 210's direct drive. On the other had, there were problems on early Rotax 185's. Ultraflight had a series II factory demo plane fitted with 210's in 1983 for evaluation when I worked there. I can tell you that they produced a very noticeable boost in rate of climb over a Rotax 185 (when both were fitted with the stacked factory props), because I flew both on the same planes. They also built and flew re-drives on both the Rotax and Solo engines that year.

Ultraflight used the Rotax engines because they were much more suitable, powerful, and long lived than converted chainsaw engines, less expensive, and locally available. The Solo was not locally available, and would have cost the factory more. This is an important point, because even with the smaller engines used on a Lazair, compared to other popular Ultralights, it used TWO. That, and the choice of materials and complexity made the Lazair more costly to produce than most of its competitors.

Lastly, and most importantly, Dale Kramer (who designed the Lazair and owned the company), had a personal bias against reduction drives. He much preferred the simplicity and weight savings of direct drive. Very few belt or gear reduction type re-drives of the early 80's were all that trouble free anyway. He continued to investigate larger engines running direct drive props, because that's what he felt was a better way to go.

Chappy


Good information. So Lazair did test Solo engines and went with the 9.5 Rotax because of cost and availability. You say both engines were fitted with doubled stacked props. That must have been very inefficent for the Solos and you say it still outclimbed the 9.5s ? I wonder what the results would have been using a 36x11 prop. According to this article ( http://airsports.fai.org/nov99/nov990b.html)the props would turn around 5,400rpm driect which is less than the Rotax 9.5 with stacked props. The neat part about Solos is maybe you could actually shave a few pounds off the plane and add 20lbs of power. You say you flew the Solos. How did the plane fly single engine.

Evidently Mr. Kramer was trying to minimize cost complexity, and weight of the planes by using the direct drives. I'd say that was a pretty smart thing to do if you stand back and look at it.

I don't guess there is anything wrong with reduction drives but it seems like overkill to add way more thrust than what the single seat planes need for safe flight and good numbers. I looked at the Lazairforce Solo motor section and it seems someone long ago took the straight forward approach of powering a Lazair with direct Solos. I'm just wondering if there are any reasons why this shouldn't be done again. If someone was looking to power a Lazair and keep it basically traditional wouldn't the economical Solo be a solution ? From what I've read new Rotax 9.5s are very expensive.
Guest
 

Postby Chappy » Mon Nov 08, 2004 12:31 am

To be clear, Ultraflight chose the Rotax because it was a locally obtainable engine. The Solo wasn't even tested until well after the Rotax was chosen.

Two of the factory props was too little for the Solo, three too much. The factory developed an adjustable prop also made by them, with the injected components made at Dale's Dad's company (by that time being run by Dale's brother). Unfortunately (and that's an understatement), it was not successful, as the Solo with that prop was a very nice setup. If you search this site, you will find a detailed history of their ill fated adjustable prop.

Single engine operation was very similar with the Solo, as it is with most engines fitted. The problem with going to higher output engines to increase single engine climb is that the extra power requires more rudder deflection to counter the asymmetrical thrust. That extra rudder deflection creates lots of additional drag, more or less negating the extra power of the remaining engine.

I tried to reduce this effect when I fitted my little re-drive Pioneers on my very early Series I by canting each engine assembly outward several degrees. When the plane yaws toward the dead engine, the good engine will tend to contribute less turning thrust. Having the engines canted outward is a trade off, as it gives up some efficiency in normal forward flight. It seemed to me to be a worthwhile compromise, as far as I could tell.

Fitting huge engines on the Lazair will produce amazing climb rates. Unfortunately, because of many design features of the plane, it just doesn't produce corresponding speed increases. A very thick, high lift airfoil wing built with excessive washout, an unfaired cockpit, and an extreme positive wing angle of incidence that causes the boom tube to be dragged through the airstream tail high at cruise speed produces very high drag as power and speed are increased. A Series III with two direct drive KFM's set up to run at about 16-18 HP each would only drag us through the air at no more than 75 mph. (The VNE of that same airframe was published at that time at only 55 mph.) The ride is very rough even in relatively smooth air at 70-75 mph!

Because of this, and because I think the Lazair is at its best at much slower speeds, I'm a big fan of smaller engines turning slower, more efficient, larger diameter props. Direct drive is really more suitable for higher cruise speeds, IMHO, where prop slippage is less pronounced.

Chappy
Chappy
LazairNUT
 
Posts: 330
Joined: Wed Jan 28, 2004 9:57 pm
Location: Northern Virginia, USA

Next

Return to Re-Building tips and info

Who is online

Users browsing this forum: No registered users and 4 guests

cron