Brodhead Pietenpol Association

Original Posted By: Jim Markle

Original Posted By: owner-pietenpol-list-server(at)matronics.com
That much power (300 Hp) would be spectacularly awesome in a Piet...for afew minutes of flight time. (Math is easier for me if we just go with 100 Hp, a more reasonable numberfor Piets, so that is what I use here initially.)The best energy storage density of lithium-ion batteries these days isaround 200 W-hr/Kg, or about 0.12 Hp-Hr/Lb. To get 100 Hp for one hourwould require about 850 Lbs of batteries (at an unattainable 100%efficiency). A Piet needs about 30-40 Hp to cruise straight and level at a relativelyslow speed. Consider that two hours of gasoline (at 5 gph) is about 60 lbs.I'm guessing that the electric motor weighs something less than a 100 Hpaircraft motor so assume a motor that weighs 100 lb less than its internalcombustion counterpart. To cruise electrically for two hours, you wouldneed about 600 Lb of lithium-ion batteries (with something more fortakeoff). Minus the motor and gas weight savings, that adds 440Lb to yourexisting takeoff weight. With a pre-existing 650 Lb empty weight and 200lbs of pilot, you have a 1300 Lb airplane. That might upset the stressanalysis guys, but a Piet is pretty strong. And, with 300 Hp of takeoffpower, 1300 lb will get off the ground right smartly.However, every time you climb, you eat up cruising time. Everyone, please feel free to critique my reasoning.Mike Hardaway _____

Original Posted By:> H RULE One thing the guy mentioned in the video was the torque generated > by the electric engine as compared to the gas engine.Perhaps a > different prop of newer design than the old style might be of help > here.I noticed on smaller model electric planes that the prop has > quite a bite to it.Also consider just asking for 80 hp as in my > plane instead of 100 hp.The problem in my case would be that there > is no place to plug in the batteries at the airfield.A small prop > driven generater between the landing gear could generate power to > charge asI fly along adding to the cause.The weight of the engine > and no gas tank and gasis greatly diminished giving more room for > the weight of the batteries.Batterries could be placed in the > wings as well.I don't carry passengers so I could carry more > batteries of the lithium type of coarse.I may be able to solar > charge those batteries now that I think of it.Cover the whole top > of the wing surface in solar chargers also adding to> the cause as I fly along.What do you think?> > > > > ________________________________

Original Posted By:> H RULE One thing the guy mentioned in the video was the torque generated> by the electric engine as compared to the gas engine.Perhaps a> different prop of newer design than the old style might be of help> here.I noticed on smaller model electric planes that the prop has> quite a bite to it.Also consider just asking for 80 hp as in my> plane instead of 100 hp.The problem in my case would be that there> is no place to plug in the batteries at the airfield.A small prop> driven generater between the landing gear could generate power to> charge as I fly along adding to the cause.The weight of the engine> and no gas tank and gas is greatly diminished giving more room for> the weight of the batteries.Batterries could be placed in the> wings as well.I don't carry passengers so I could carry more> batteries of the lithium type of coarse.I may be able to solar> charge those batteries now that I think of it.Cover the whole top> of the wing surface in solar chargers also adding to> the cause as I fly along.What do you think?>>> ________________________________

Original Posted By: helspersew(at)aol.com
The old version of 43.13 said a splice had to be 10:1 minimum, 12:1 preferred. As it has been pointed out, the original plans for the center splice is not the best way to go although I suppose you could, it is an experimental after all.I am building a one piece wing. If you draw it out, using the proper-sized plates on both sides of the splice, a 12:1 splice won't work and still keep the splice plates out from under the cabane fittings as is also required under 43.13 (the splice is 12", and the splice plates are supposed to be 6" on either side of the splice line, making the whole thing 24" from end to end, and the cabane fittings are not that far apart) For this reason, I made my splice 10:1. This way, it is legal and keeps the splice plates away from the cabane fittings (10" splice, plates 5" either side of the splice line for a 20" total splice, the ends are about 1" from the cabane fittings).Gene ----- Original Message -----

Original Posted By: H RULE

Original Posted By: H RULE
Subject: Re: Pietenpol-List:electric engineI did some math on electric planes and looking at converting older systems (likea Piet or Bonanza) to use an electric engine. Purely amature since "I ain'tno alectronic jenious!" but rather an infantryman.It came down to weight and speed. Electric motors tend to like higher RPMs. Sothey need a reduction and they tend to not like lower speeds. So the concept worksbetter for a sleek little speedster like a sonex rather than a barn doorlike a Piet. I have a 1948 Bonanza and there the problem is not speed but rather the weightof the aircraft and the HP of the motor needed. Taking out the old engine andgas tanks provides about 450-500 pounds. Getting a light/strong electric motoris not hard. Getting enough batteries for enough range to be useable is theproblem. Batteries are HEAVY. So putting enough batteries into the plane to getenough range would eat up all of my useable weight and even then the rangewould be marginal. The same applies to a piet as far as weight.If you look at the current electric planes they are very limited on weight carryingand range. Range is often 20 minutes to 1.5 hours. Not much reserve forany trip even just fun flying. Also there is not much potential for a quick turnaround due to recharge times.I love the idea of flying a much quieter airplane that does not pollute. I do thinkit is on the not too distant horizon but there will be adjustments. I am more than willing to be wrong on this subject. This was just my conclusionsafter discussions that I had with some electric motor gurus. Blue Skies,Steve D----- Original Message -----

Original Posted By: Tim Willis

Original Posted By: owner-pietenpol-list-server(at)matronics.com
Power is the product of torque times rotational velocity. It takes acertain amount of power to maintain a particular flight condition, whetherthe power comes at high rpm on a small prop or low rpm on a big one.Efficiency, which is measured by how much comes out vs how much is put in,is affected a lot by rpm vs. torque, but it is flight conditions thatdictate long prop slow or short prop fast. A Piet at 60 mph can fly quitewell on a long prop at low rpm but an RV-4 at 200 mph rpm cannot.The solar panels on top of the wing would, of course, add some weight butwould help recharging. However, the wind-driven generator idea is a no-go.It takes more power to drag it through the air than you get out of it inelectricity.The example I used earlier gets 1300# without a passenger, adding a flyingbuddy would make for a 1500# or so takeoff weight. You might save a few lbby sizing for a smaller motor, but not enough to obviate the need fortakeoff power to get 1200-1300# off the ground.What really makes the electric airplane a possibility is reduction in drag(not a Piet's long suit). There are some really clean and light airplanesthat take only a few horsepower to maintain straight and level flight.Motor gliders seem to be the reasonable focus for electrification and dowell with much less battery weight than we would need in a Piet.Mike Hardaway _____

Original Posted By:>> Dan Yocum
Here are a couple of shots that show the VGs on my Cub.-john-John HofmannVice-President, Information TechnologyThe Rees Group, Inc.2810 Crossroads Drive, Ste 3800Madison, WI 53718Phone: 608.443.2468 ext 150Fax: 608.443.2474Email: jhofmann(at)reesgroupinc.comOn Sep 30, 2009, at 10:21 AM, Tim Willis wrote:> >>> Answering some questions, not about dimple tape.>> Grega and Cub: The Grega plans call for Cub wings if available, > otherwise the Grega ribs one makes from Graga plans look like BP's > FC10 on the lower surface, and like a Clark Y or USA35b on the top > surface. The Cub itself used a USA35b airfoil.>> VG placement: The instructions on VGs on wings typically have them > placed at about 10 percent of the chord-- more or less that far back > from the leading edge. Instructions vary.>> Tim in central TX>> -----Original Message-----

Original Posted By: H RULE
Paul McCready did it with solar cells but he had a lot bigger wing to cover with the cells. Mike ----- Original Message -----

Original Posted By: "Michael McGowan"
Steve,I appreciate your research on this topic. For me, the allure of electric flight is not environmental, it's purely financial. The dream would be to charge your aircraft using solar cells on the hangar roof and "fly for free".It will happen in my lifetime, and I will fly one. For reference, I'm 31.Don't get me wrong, boys, I still love the sound of an A-65 and the smell of burnt 100LL! But technology sure is cool, too!Wayne Bressler Jr.Taildraggers, Inc.taildraggersinc.comSent from the phone that made the Blackberry obsolete.________________________________________________________________________________

Original Posted By: "Dortch, Steven D MAJ NG NG NGB"
The electric tractor conversions I am familar with use series wound motors which put out maximum torque at zero rpm. They are happy at low rpm. Mike----- Original Message -----

Original Posted By: Michael McGowan
Well, first of all yes, the bending and shear loads are very low in the center of the one-piece wing. That is why the original splice probably worked fine, and most likely still would, although I would never splice it that way. There are a couple of reasons not to extend the splice plates under the cabane fittings. First, because 43.13 and prior practice specifically states that the plates shall not extend under any fitting. I've never seen anything say "unless you artificially extend the plates longer than required to make them go under a fitting." Second, it adds weight for no benefit whatsoever. The cabane fittings don't need plates under them, (even if they did, you would only be adding a plate on one side) and now the fitting has to be wider and the bolts longer (more weight) for no real reason. If you are talking about extending the plates the full width on BOTH sides of the spar, why not extend them all the way out to the wingtips? Not trying to be funny, but just stating that the same logic would apply.Remember, keep it light. You can add this or that "to make it a little stronger," when it does not need it, until it won't fly anymore.Gene ----- Original Message -----

Original Posted By: owner-pietenpol-list-server(at)matronics.com
Right on. _____

Original Posted By: owner-pietenpol-list-server(at)matronics.com
When I was working for NASA, we flew McCready's Gossamer Penguin, thebattery-powered predecessor to the Solar Challenger, out on Rogers Lake bed.The bird flew so slow that we could almost run alongside and it carried acute-as-a-button ninety-pound pilot named Janice Brown for only a fewminutes of flight. A huge wing and extremely light construction made for aplane that could hold straight and level on about one Hp.That was twenty-seven years ago, way back in the steady progression of motorand battery technology.Mike Hardaway _____

Original Posted By: Gene Rambo
You're right Thanks Mike ----- Original Message -----

Original Posted By: Robert Ray
You could always put a baseball card in the fan. :-)Clif> > Don't get me wrong, boys, I still love the sound of an A-65 and the > smell of burnt 100LL! But technology sure is cool, too!> > Wayne Bressler Jr.________________________________________________________________________________Date: Thu, 1 Oct 2009 02:33:34 -0400Subject: Re: Pietenpol-List: Riblett 612 Leading Edge

Original Posted By: H RULE