Sygy00

Sorry for the confusion, I guess I should have been a little more careful. What I meant was that for a given amount of power, a device designed for 6V will draw less current than one designed for 4.8V. When you apply a higher voltage the current draw and total power incease, but the total energy used remains about the same, so the mah of the battery is not affected much by the higher voltage. And if fact, you can often use a lower mah battery with higher voltage as I'll explain in a minute. What is not clear to many is that a high current draw the battery itself will dissapate (waste) a lot of energy (by heating up) and in general the lower the battery voltage the worse this will be.

I only used a very small AAA 6V 1000mah battery for my 25-46 eflite retracts. If I had used a 4.8V AAA battery I doubt the gear would have worked well because the current draw would drop the supply voltage of that small battery to a low level and possibly cause them to do a low voltage cut out.

Also note that the capacity of the battery is not well reflected by the mah rating unless all the batteries you are comparing have the same voltage. What is important is the volts times the mah or milliwatt-hours, which is the total energy the battery can produce. That is why a 6V battery with a 800 mah rating (4800 mw-hours) will do the same work as a 4.8V 1000mah (also 4800 mw-hours) battery, and if fact a little more as the higher voltage battery will waste less.

I sure am getting long winded in my old age. Hope this helps.

BillS

I asked about wing area because landing at home is difficult when wing loading is above 24oz./sq. ft. The trees and high grass love airplanes.

Does anyone have the area or better yet wing loading?


Bill

Sygy00

Bill,

I had to guess a bit at the original wing tip cord, but here is what i got for the original F20 out of the box:
- wing area 687.5 sq.in
- my plane weighed about 6.5 lbs before retracts (which I would assume is roughly average for this plane)
- result is a wing loading of 21.8 oz/sq.ft, which is not high.

I usually consider anything under 20 oz/ft low, 20-30 moderate, and over30 a bit on the high side. In fact, I like to keep my planes at 22-26 oz/ft as it is not too light and not too high. Where I fly is most often windy (10-15mph) so a little higher wing loading helps tokeep it from bouncing around so much on landing.

I am flying my modified F20 right now as follows and if flys great and lands very slow:
- wing area 606.4 sq.in
- weight 7.5 lbs
- wing loading 28.5 oz/ft

You can view one of videos above to see how it landed nicely even at 7.5 lbs and withclipped wings. I do use flaperons (about8-10 deg aileron droop) and it doesmake a noticeable difference on general handling when landing. But the plane lands just fine even without them. If you can program your radio for flaperons (by drooping ailerons)you might give it a try. Just don't use more than about 10 deg.

BillS

Sygy00

A couple of miscellaneous thoughts. Many airplanes during WWII left part of the wheel extend into the airstream when retracted.

Wing loading of 28.5 oz./sq. ft. is likely to mean 29mph landing speed. The speed is comfortable at a flight field but dangerous to the trees and airplane at my home.

I can follow your flaperon and fence advice but need to design compromise the landing speed for the two environments that I fly.

Thanks for your great advice.

Bill

cap3Der

My Feedback: (9)

Sorry, Bill, for late response, I just saw this post. Here are answers to your questions: Cord at centerline is 15", wing tip 8", WS-56", so wing area = 644 sq in.

cap3Der

My Feedback: (9)

I have on my F-20 Ultra Light 3" foam wheels from GreatPlanes http://www3.towerhobbies.com/cgi-bin...&I=LXK150&P=SM Tru-Turn aluminum spinner, and Li-On battery by Troy build 2800 mAmps, so weigh is 6Lb(or 96 Oz), so wing loading is ~ 21Oz./sq. ft. I hope it helps. Plane fly like its on the rails, rock solid, very easy to land with a nose high glide. Quality of the kit is great, the only thing is replace a stock control horns with metal ones. Good Luck!

Crazy4Flight

My Feedback: (540)

I had one with a Sport JETT .50 it hauled butt and impress the spectaters at a R/C & full scale picnic!

Then a buddy bought it and drilled 8" deep several months later