Scratch built ??
#1
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Scratch built ??
After a couple years of trainers, then a sturdy birdy that I put ailerons on (and built a new set of wings for twice.. lol..) I decided to scratch build an EP park slowflyer. Its just 3 channel (rudder, elevator, throttle) until I can assure it's gonna be light enuf to fly first. Well the dimensions are L-20" span- 27" cord- 4" with hitec hs55 servos, gutted old 6 channel Futaba reciever, C-10 ESC, Electrifly GRU with 370 motor and 10x4.5 prop. The wings are hot wire cut from high density white styro with about 15* dihedral. Whats a good weight to aim for? I am trying to keep it as light as possible. I will post some pics of this flying POS in a while lol..
#5
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RE: Scratch built ??
This website has gone straight down the crapper, and it parallels society. People arent building for themselves anymore, they wait for a company to make what they want. Not even 5 years ago this site was completely different, a lot of people building what they wanted and taking pride in it and the pros could tell you if your build was done right or not, but not anymore...
#6
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RE: Scratch built ??
Here's the best info I could dig up, slowstang. The info was taken from an old "Design and build your own r/c aircraft" authored by Kenneth L. Smith. I have built several with the info from this publication and they all flew well.
Wing area 140 - 250 sq in. is in the .049 engine range.
There is no info for a wing in the 100 sg in. range, but suggests a weight of 20 oz. for a wing of 250 sq in.. Wing loading on this 250 sq in. wing carrying a weight of 20 oz. is 11.5 0z/sq ft. for a high wing rainer. A200 sq/in wing carrying 20 oz. will have a wing loading of 14 oz sq/ft, this figure is for a shoulder wing sport.
6-8 degrees total dihedral for a high wing 3 channel trainer is recommended.
I am just guessing here, but 8 oz. all up weight should be good.
Your dimensions look good, but I can't really be sure from the pictures. Good luck and remember: the first one is only a stepping stone to a really great flying model.
Wing area 140 - 250 sq in. is in the .049 engine range.
There is no info for a wing in the 100 sg in. range, but suggests a weight of 20 oz. for a wing of 250 sq in.. Wing loading on this 250 sq in. wing carrying a weight of 20 oz. is 11.5 0z/sq ft. for a high wing rainer. A200 sq/in wing carrying 20 oz. will have a wing loading of 14 oz sq/ft, this figure is for a shoulder wing sport.
6-8 degrees total dihedral for a high wing 3 channel trainer is recommended.
I am just guessing here, but 8 oz. all up weight should be good.
Your dimensions look good, but I can't really be sure from the pictures. Good luck and remember: the first one is only a stepping stone to a really great flying model.
#7
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RE: Scratch built ??
Thank you for your reply! I'm gonna do some glide testing after its all balanced out and decide if I need to make a new wing with more span and chord. The more I look at it, the more I think the wing loading will be too high. I also have no way of weighing this thing accurately (to the ounce/gram) and theres a lot I could have done to make it lighter but what I got is what I got! Live and learn from the experienced guys I guess!
#8
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RE: Scratch built ??
I forget to mention something, Slowstang. Google RCM Plans. Go to requested articles. The Chuck Cunningham and Ken Williard aryicles will be a big help. Print those articles. A lot of older and valuable info has been taken off the web.
So, how did it fly?
So, how did it fly?
#9
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RE: Scratch built ??
Not bad "slowstang88", if you'd like to build a kit next time you might want to look at the Herr Engineering Star Lite, Its supose to be a three channel, throttle, aelirons and rudder but I decide I couldn't live with out aelirons so I modified the wings.
Here's a link to my thread www.rcuniverse.com/forum/m_11179008/tm.htm
If you get bored, let me know what you think. Give me a shout if you have any questions.
Here's a link to my thread www.rcuniverse.com/forum/m_11179008/tm.htm
If you get bored, let me know what you think. Give me a shout if you have any questions.
#10
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RE: Scratch built ??
The articles on rcm really take me back, I actually remember reading some of those articles in print back in the day, thanks for the trip down memory lane!