First Flight

[HELModels]

I've almost finished the Darn thing, minus the correct battery. I used the wrong battery/too few cells and could only manage a weak climb. CG was too rearward and stall spin was a problem, of course. Busted the only prop too.
Have more than one on hand and recheck CG is my advice.

Anyway, it is based on the Storch. It has a 32" inch span and wingloading of about 8oz/sq ft.

So, busted prop meant no powered flight. This meant tossing it and seeing how it really wants to fly. Like a champ!! Neutral trim allowed the flattest glide I have ever seen from a model so small. There was absolutely no wind and with a healthy level toss, it flew about 50 yards with just the slightest occasional imput on the rudder. This was from a slightly elevated start point. I estimate I was about 15 feet above the landing elevation. These are estimates, but that works out to a glide ratio of 10:1.

I modified an RAF airfoil using Dr. Drelas Xfoil and at a Reynold's of 100,000 that program estimated L/D ratio of 38:1

Is the .75 drop in L/D due to lower reynold's number? The chord is about 4"

[Ollie]

Profili and XFoil only deal with the profile drag of the airfoil.

The whole plane has profile drag, induced drag and parasitic drag. The lift to drag ratio of the whole plane is the lift divided by the sum of all three types of drag. At slow speeds, just above stall, the induced drag dominates because it is larger than the other two combined. When the plane is trimmed to fly at its maximum lift to drag ratio, the induced drag is exactly half of the total drag.

BTW, with a wing loading of 8 ounces per square foot, a wing chord of 4 inches and a slow trimmed flight speed, the reynolds number is probably closer to 50,000 than 100,000.

[HELModels]

I went and paced off the distance and the glide ratio is more like 20:1.
That agrees with the qualitative observation of a real nice flat glide.

I was under the impression that at lower reynolds, the L/D is pretty much the Glide Ratio because the profile and parasitic drag is actually less due to the reduced reynolds?

However the actual drag components add up, it should be a nice flyer.

[HELModels]

I got the correct battery installed and new prop and gave it another go.
Double checked the CG - seemed about right. Advanced the throttle to full, just about flew out of my hand. Nice climb out, didnt touch the stick too much, dont overcontrol. Arghh, trees, a touch of rudder, good, cleared em. Then something happened. I touched elevator and got confused. Full up, Full down, nose dive from 100 feet. Quickly shut throttle down before impact, but went in vertically. Prop was still good but the servos broke loose from the mount. Amazingly no damage to anything else and it hit Hard.

Problem was elevator switch on the transmitter was reversed. I remounted the servos and few hours later got the nerve to try it again. Full throttle, nice climb, small inputs. Then it happened! A 100 foot pine tree I managed to avoid before snagged my creation ever so gently. I needed 1 more foot of altitude to clear it, but had leveled my attitude just a moment before. I tried full throttle to see if it would free itself, but only raised the nose up a little. Tried wiggling rudder and elevator, nope. Went and got a bunch of tennis balls and luckily clipped the wing enough to give me hope. Several throws later it was free and diving for the ground and instead landed gently in the lowest set of branches. Again, No Damage!

I Will Find a Suitable Field before my luck runs out.

[BMatthews]

Good idea! LOL

Hope the rest of your flying works out better.

And I see you've also learned the lesson about the preflight check for control operation AND correct directions. It may seem like overkill but with our new transmitters it's a good habit to get into even if you do only have one model and reciever for now.

[HELModels]

Right you are! Preflight Check does not mean what amount of $$$$ one spends to get airborne.

It is amazing how rugid this plane is. scratch built, designed on the fly, by a beginner, and yet can survive a full throttle vertical nose dive from altitude. Exactly what a beginner needs.

[vintage1]

You will soon learn to fly around the trees tho. Think of it as an extra challenge.

[HELModels]

I could easily learn to fly around trees and perform a thorough preflight, but how do I fly around RF interference? I think the horrendous nose dive was due to contributory interference. Reversed channel switch AND RF interference - a bad combination. I noticed when trying to retrieve from the tree some glitching of the servos and was not due to low battery as voltage check revealed excellent voltage. This servo glitching did corresponded to heavies flying obliquely overhead. Eyes were already skyward so the correlation was obvious.