ryanjames170
Well-Known Member
What UL desighns could be used for my idea of a Twin using 212, 301cc 4 stroke engine?
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Which engine in particular, and how much does it weigh?
ryanjames170
Well-Known Member
well the Predator 301 weighs in at 57lbs and the 212 weighs in at 35lbs before you strip them down. still waiting on Aprox HP/RPM numbers from a place for moded engines in Stage one this is just cleaning up exhaust and intake air flow. as stock air cleaner and exhaust eat up 2.5HP on the 212.
Home Depot Plane, for 1, at least with the 212's, but I don't know what it's reputation is. I suppose you could put a cross bar on the Sky Pup's engine mount, and reinforce the fuselage a bit for the twisting forces, but the whole installation would have to weigh less than 62 lbs. This could be done, I suppose, with other front engine ultralights, but it would be ugly. I suspect the Lazair was meant only for two 2 strokes and might not be up to the extra weight in that location. Suggest choosing an aircraft that has a relatively long wing if you're going to use the 212's. I've seen pictures of Kolbs with two engines, but I don't know anything about it and I doubt if the span is long enough for the 212's.
Just as a warning as to how ugly things can get, here's a single engine plane that's been converted to a twin by the method I mentioned above.
Just as a warning as to how ugly things can get, here's a single engine plane that's been converted to a twin by the method I mentioned above.
saini flyer
Well-Known Member
This configuration has been talked about before. I would like to know of a better reason to why this is not the simplest way to go from a single to twin while keeping thrustline closer to the center; the most recent being the jabiru twin: http://www.jabiru.co.za/aircraft/j432.html
Now regarding being ugly, why not compliment the single 212 in the center with twin electric RC motors ([email protected]$196 each & 2 lbs https://hobbyking.com/en_us/turnigy-rotomax-50cc-size-brushless-outrunner-motor.html) on the sides (like twin jabiru) making it a three engine plane. Use the electric motors only for TO&L and fold back the props (http://www.espritmodel.com/sailplane-folding-propellers-spinners.aspx). The batteries can go in the cockpit and the added weight at the FWF is <10lb combined.
Ofcourse it cant beat the price on the predator 212......
Now regarding being ugly, why not compliment the single 212 in the center with twin electric RC motors ([email protected]$196 each & 2 lbs https://hobbyking.com/en_us/turnigy-rotomax-50cc-size-brushless-outrunner-motor.html) on the sides (like twin jabiru) making it a three engine plane. Use the electric motors only for TO&L and fold back the props (http://www.espritmodel.com/sailplane-folding-propellers-spinners.aspx). The batteries can go in the cockpit and the added weight at the FWF is <10lb combined.
Ofcourse it cant beat the price on the predator 212......
Ultralight glider rules are weight less than 155lbs and powered is less than 254lbs so from that you can conclude that motor mount, fuel tank, fuel lines, throttle and mixture controls, engine, propeller and any other items to make a glider powered are going to weigh around 99lbs or less, not counting the fact that you could build an airframe that weighs less than 155lbs? Or to support the extra weight the airframe may need to weigh more than 155lbs, depends on how you are building it. That gives a ballpark.
I thought the Legal Eagle would look good with two engines mounted like a Cri-Cri and be simple and straightforward enough.
Cri-Cri and Legal Eagle
https://www.bing.com/search?q=cri+cri+airplane&form=EDGTCT&qs=AS&cvid=e7410dcbb88f4207a46e7ab8181bfa7f&refig=4ceecabebd9e4df0b6e1c7bb6e842394&cc=US&setlang=en-US&elv=AY3!uAY7tbNNZGZ2yiGNjfM8fS6YXbPMrfEo*RYyhrAUiEDjn3CfxYGqChp4AkWpGYbiRSRYnV4XdbJ1iGGDkVi11cInV!*kb!gGRevoPyyN&PC=LCTS
http://www.betterhalfvw.com/
https://www.bing.com/search?q=cri+cri+airplane&form=EDGTCT&qs=AS&cvid=e7410dcbb88f4207a46e7ab8181bfa7f&refig=4ceecabebd9e4df0b6e1c7bb6e842394&cc=US&setlang=en-US&elv=AY3!uAY7tbNNZGZ2yiGNjfM8fS6YXbPMrfEo*RYyhrAUiEDjn3CfxYGqChp4AkWpGYbiRSRYnV4XdbJ1iGGDkVi11cInV!*kb!gGRevoPyyN&PC=LCTS
http://www.betterhalfvw.com/
ryanjames170
Well-Known Member
Tri motor would be neat but you could only doing that with the 212s anything else other then a 2 stroke would be to heavy.
Judging by the specs on the web site, it's a sad fact that the Legal Eagle isn't legal. The airspeed indicator probably says 25 mph when it stalls, due to the pitch angle. It doesn't meet the specs in Appendix 2 of Part 103-7 for calculating stall speed. In order to meet the 24 knot requirement in real life, it would have to have a WING lift coefficient above 2! Plus, the span is short so the minimum power required will be more than longer winged ultralights. The Legal Eagle XL is actually much closer to legal. I think if you gave it flaps over more than half the wing span, it WOULD be legal. Or, at least, the stall speed calculations would make it legal. Plus you have a couple of feet more wing. Flaps, of course, require some structural redesign and add weight. Many people have pointed out that the FAA, so far, hasn't got too excited if an ultralight is a little overweight.
Both are designed for heavy engines. Wikipedia says that the Better Half VW weighs 88 lbs dry, and then there's the prop. I suspect it might be possible to use two stripped 301 cc engines and meet that weight, even with some extra reinforcement to handle the new engine mount configuration. But you'd probably have to hop them up some just to fly around comfortably, with a lot more in reserve in case you need to fly with one engine. In that case, you'd might have to figure out a way to make sure the pilot can't use the extra power unless the other engine is out. Or maybe the aircraft is draggy enough already.. Or you could figure out some other way to limit the top speed.
Both are designed for heavy engines. Wikipedia says that the Better Half VW weighs 88 lbs dry, and then there's the prop. I suspect it might be possible to use two stripped 301 cc engines and meet that weight, even with some extra reinforcement to handle the new engine mount configuration. But you'd probably have to hop them up some just to fly around comfortably, with a lot more in reserve in case you need to fly with one engine. In that case, you'd might have to figure out a way to make sure the pilot can't use the extra power unless the other engine is out. Or maybe the aircraft is draggy enough already.. Or you could figure out some other way to limit the top speed.
What do 212's weigh? Aircraft weight not out of the box.
ryanjames170
Well-Known Member
I might do some looking into a stripped 420CC engine as there is a list of things it really don't need on it and might come in close to what would be needed
ryanjames170
Well-Known Member
I can strip one down if you guys like and weigh it.
ryanjames170
Well-Known Member
Are you sure it isn't legal? Because fixing something that doesn't need fixing is a waste of time.
Would it have to be flaps? Could you make the chord a smidge longer? Less complicated as it doesn't require linkage and hinges and therefore lighter.
Wonder how the FAA would feel about Gurney flaps? They would be easy and light to add. :gig:
How about this?
http://www.vegascarts.com/460cc-go-kart-racing-engine-barebones-builder-kit-p/vrx46-diy.htm
Not sure how it does when constrained to relatively low rpm.
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The Cloudster is another relatively long winged ultralight I didn't mention earlier. The original was significantly longer, but the current one is 31 feet or so. Maybe you could get them to cough up plans for the older version. Longer wings mean somewhat smaller engines are needed. The old Le Pelican had a 37 foot wingspan, but I don't know where you're going to find plans for it.
You might find something at vula.org, though you're probably going to have to take the names and check them out elsewhere.
That might work too. But you'd have to add a lot. And then make the tail bigger, or further aft.. (You'd have to make the tail bigger or further aft for flaps too, most likely.) You MIGHT be able to find an unusual, high lift airfoil that would make up a fair amount of the difference. But then, if the FAA asked, you'd have to test. (I haven't heard of them ever requiring this.) Maybe fixed slats or vortex generators. The latter can be very light and simple, and I suspect fixed slats could be relatively simple. I don't know what they do to the pitching moment, but presumably less than flaps do. Either one would reduce your top speed.
ryanjames170
Well-Known Member
I think it would put out the HP but it might not do so well in the weight category though the 420cc engine is a hefty 73lbs stock..
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