|Apr 11, 2013, 09:44 PM|
Kloud Queen balancing and maiden flight
So where is a 1938 Kloud Queen supposed to balance? Seems like a reasonable question to me. The plans do not provide any clues. I guess the cg must be located using some old school free-flight rule of thumb or something. So I went with what I know. Conventional non-lifting stab and flat bottomed airfoil wisdom would indicate a distance 33% the cord length from the leading edge. Well that's easy, 12" cord wing places the cg at 4" from the leading edge. Hmm seems tail heavy at 4" and seems to want to balance on the spar, which is located at 5" from the leading edge. So I grab some conveniently available weight in the form of some rubber drink coasters that weigh 2 oz each. It took four coasters placed on the nose to get it to balance at 4". Having to add 8 oz of lead to my already 3.99 pound airplane did not thrill me. Now of course this is the electric setup and with the necessary 4-cell 2600 mAh battery it's 5.6 oz heavier than the ignition engine setup. So I figured the ignition setup would require an additional 11.5 oz of lead to get the correct cg! Not cool. After some discussions with Leadchucker I decided to add less than half the necessary weight. It was all very scientific. I told Leadchucker of the required 8 oz nose lead and he said "I'd try it with half of that.". Now where did I put the stick-on lead weights? The package I found was already open and half the weights were gone, leaving me with only 3 oz. So 3 oz it was. This resulted in the following configuration for the first electric powered flight:
AUW: 4.18 lbs
Wing Loading: 11.6 oz/ft^2
Propeller: APC 13x6.5E
Input Power: 760W
I was really hoping for a wing loading somewhere between 8 and 10 oz/ft^2. It's not like I built the plane heavy. It was pretty much constructed in accordance with the plans. The only significant deviations were adding the control surfaces with their hinges, push rods, and horns. I considered that going in and made it a point to try to build the tail light. After yet another discussion with Leadchucker we concluded that perhaps this is how it is with a Kloud Queen. So at this point I was kind of disappointed with visions of my shiny new plane sinking like a brick in moderate lift.
On Wednesday, March 10th I decided to fly this turkey. Gusty winds in the 15-18 mph range didn't deter me. It's a contest plane and in a contest you fly in what ever conditions you are given. It has to be tolerant of some wind. Leadchucker manned the camera while I manned the transmitter. Remind me to hire a better camera man. What, no landing? Seriously, you didn't film a landing? Really?
It seems to fly pretty well. I was comfortable with it almost instantly. No bad habits, no dutch roll. Slows down real nice. Maybe a touch tail heavy, but then I like my thermal planes a little tail heavy. It seems to indicate lift pretty well and I did manage to get it to skip off some late evening bubbles. I think my concerns about the weight and wing loading might have been for nothing. The controls are very responsive. With a rudder and elevator that are approaching 3D size, that's to be expected. Landings (thank you very much, Leadchucker ), are nice and gentle. Without wind gusts, I suspect that it will almost land itself.
Well, I can't wait to fly it again! The NWS is calling for 13 mph wind over the weekend, so I might sneak out for a couple of hours and get my fix. The ignition setup will need 8 oz of nose lead to get the cg where it is with the electric setup. I plan to try out some Brown Junior powered flights in the next couple of weeks. Perhaps the new camera man will even capture a landing.