Would you buy a MPG wonder if it was available ?

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Condor

Active Member
Who supervises that no copies are being taken from the sent copies or is this like gentleman to gentleman business ?
If you notice, I did NOT say SolidWorks 3D, I said a 3D read only eDrawing or 3D PDF copy of the model. You can set up those copies without measurement ability, so no one can copy it. The idea is to be able to identify the parts easily. Whenever I see a plan, it takes me "forever" to see which part is which and how all the things go together. Particularly when a complex airplane comes with a 20 page (only) documentation. Somewhere earlier you said, it will take a few hundred hours to put it together. THAT is the key. Some builders have money, some don't, but NOBODY has time anymore. So whatever help you can give to speed up construction will be appreciated. A 3D model is just one of those item. (An accurate Bill of Material is another, a material kit is another, full size templates another, step-by-step pictorial instruction and videos are another, set-up a Yahoo group is another).

(And I would prefer the high MPG/small engine 100mph cruise version if I would be on the market for one.)

topspeed100

Banned
If you notice, I did NOT say SolidWorks 3D, I said a 3D read only eDrawing or 3D PDF copy of the model. You can set up those copies without measurement ability, so no one can copy it. The idea is to be able to identify the parts easily. Whenever I see a plan, it takes me "forever" to see which part is which and how all the things go together. Particularly when a complex airplane comes with a 20 page (only) documentation. Somewhere earlier you said, it will take a few hundred hours to put it together. THAT is the key. Some builders have money, some don't, but NOBODY has time anymore. So whatever help you can give to speed up construction will be appreciated. A 3D model is just one of those item. (An accurate Bill of Material is another, a material kit is another, full size templates another, step-by-step pictorial instruction and videos are another, set-up a Yahoo group is another).

(And I would prefer the high MPG/small engine 100mph cruise version if I would be on the market for one.)
Well I don't see any harm in the unscaled 3D copying except that the idea is being copied as soon as you start to deliver drawings in general..2D and 3D. But since motorgliderpilot said..no one in Finland is interested about this..I have very little means left to market or made it available.

...and you can get the 100 mph for it since the 80 mph 123 mpg was counted at 8-10 hp of the 18 hp engine..possibly 110 mph is the top speed at full throttle which burns considerably more ( twice ).

Also the real life wheels will deteriorate the MPG a bit and possibly the top speed will decrease to 100-105 mph..the wheels that I have now are for hard deck surfaces only..if we put bigger rubber tyres on it the drag will increase 3-5 %..it has now 250 mm dia wheels that are good but not good on grassfields like where motorgliderpilot operates. Since I only know 2 grassfields in Finland I don't think that is a big issue, but changing them will definitely drop the MPG into 100-110 mpg region.

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Condor

Active Member
Well I don't see any harm in the unscaled 3D copying except that the idea is being copied as soon as you start to deliver drawings in general...2D and 3D.

topspeed100

Banned
“I found a new engine that burns only 1,5 liter per hour and also produces 18 hp...and is a proven reliable 4-stroke...yippekaeyeea ! “

I advice you to take a real close look at that engine before you really count on those numbers.
If it burns 1,5 litre per hour it delivers also only 4 to 5 HP.
And if the engine is really capable of delivering 18 HP it's probably closer to 3 HP than 5...
Well the B&S is 640 ccm and this is 150 ccm 4 -stroke on Swift; Features

It says 1,5 l/h. Paraglider Radne consumes 2,5 litre and it is 2-stroke ( at 8-10 hp ).

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@hogheadv2; My plane is intented to fit LSA ( FAI microlite )..not PART 103..wing is too small. Swift might be Part 103...30 mph stall ? My intention is to make a plane that can be stored on a 3 x 10 ft shelve for the winter...indoors....and fly a bit faster than a Swift.

topspeed100

Banned
“I found a new engine that burns only 1,5 liter per hour and also produces 18 hp...and is a proven reliable 4-stroke...yippekaeyeea ! “

I advice you to take a real close look at that engine before you really count on those numbers.
If it burns 1,5 litre per hour it delivers also only 4 to 5 HP.
And if the engine is really capable of delivering 18 HP it's probably closer to 3 HP than 5...

Furthermore...SFC of a 4-stroke ( good ) is 0,25 liters per HR / 1 hp. So 1,5 liters is actually 6 hp even. 2-Stroke is 340-400 ml at each 1 hp in an hour.

Lemans

Well-Known Member
"Furthermore...SFC of a 4-stroke ( good ) is 0,25 liters per HR / 1 hp. So 1,5 liters is actually 6 hp even. 2-Stroke is 340-400 ml at each 1 hp in an hour. "

Yes, SFC of a 4-stroke is 0,25 litters /hour at (or close to) max. torque rpm and at full throttle.
There is a link for some nice graphs in another post;

http://ecomodder.com/wiki/index.php?title=Brake_Specific_Fuel_Consumption_(B SFC)_Maps&oldid=2517

If you take a close look you will notice a steep increase of SFC if you use only a bit of the max rated torque. If you use the 18 HP engine for only 4HP , SFC should be more in the 0,4/0,5 litter /HP/hour. For your 1,5 litters per hour you will probably receive less than 4HP.

topspeed100

Banned
Okay..I stand corrected.

WonderousMountain

Well-Known Member
If you look at this chart the 250g/Kwh line, is placed at three 3000 RPM and a torque of 55Nm. 5,000 rpm has 75Nm at max torque. Upper power factor is 5K*75=375, lower power factor 3K*55=165, ratio of power factor 33/75 or 44%. However looking at the chart again, it's easy to see that if we wanted to use less power, ideally we'd reduce the RPM but keep torque nearly constant. Low fuel burn can be maintained until about 2,500RPM further reducing our power level to 36% of upper power factor. If the upper limit was 18 HP and the engine BSFC chart equal to this one he would be using .250*6(1hp/.746)=1.119L/hp/hr while producing 6hp.

The difficulty will be matching prop and engine to ideal settings in real world. Also, this is an efficient four stroke, we would need Bailey's 175 chart for a meaningful comparison.

I have the larger 1.3 4cylinder version of this motor.

Blessings,

Wonderous Mountain

Lemans

Well-Known Member
“If the upper limit was 18 HP and the engine BSFC chart equal to this one he would be using .250*6(1hp/.746)=1.119L/hp/hr while producing 6hp.”

I don't think this BSFC chart is comparable with the one of the high powered para-glider engine.
This kind of 4-stroke engines have not a flat torque curve but peak more in the 8000 rpm range.
Besides that, nice piece of work.
It happens to often that manufacturers use figures whiles telling only a part of the story.
They let believe what costumers like to believe.

WonderousMountain

Well-Known Member
The idea that this engine actually produced 20Hp/gal is kinda laughable, we would also be surprised if it produced 20 Hp.... but probably fifteen is readily achievable. That's a fair point, aircraft engines are tuned to around 75% power, running below 50% power is not good for some engines.

Topspeed, you should see if they'll send you some literature so you can get an idea what you're really getting.

topspeed100

Banned
The idea that this engine actually produced 20Hp/gal is kinda laughable, we would also be surprised if it produced 20 Hp.... but probably fifteen is readily achievable. That's a fair point, aircraft engines are tuned to around 75% power, running below 50% power is not good for some engines.

Topspeed, you should see if they'll send you some literature so you can get an idea what you're really getting.
I have asked them but got no reply. I think I might visit them soon..I am going to England this spring to check few ACs at Old Warden.

WonderousMountain

Well-Known Member
Don't buy an engine from a company that can't be bothered to reply. That's not class. If they can't provide potential buyers with service, how do you know they can provide service to post buyers, or even took the time to make a good engine in the first place. Performance may be what you're looking for, but engines require both manufacture and design detail beyond ordinary to be worth a darned. I'm sorry, but in my opinion your search is not over.

Blessings,

Wonderous Mountain

topspeed100

Banned
Finland is a marginal country and even just my name for some people means that the sender of the e-mail may be unreliable. You just have to create a personal contact to get it going....MZ people never answered either.

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