The Majik1's First Scratch Build
- Thread starter themajik1
- Start date
-
- Tags
- foamy scratchbuilt
I think any of those will work great, an 8" prop will have more than enough to get that plane around and like Pgerts said it won't break as often. One thing I noticed about those packages is that the first one I sent you only has a 1 amp BEC with the included ESC whereas the one you posted has a 3 amp BEC. Much better. I think you are on the right track, you'll just have to get a little closer to built and get a weight and decided how you want it to fly.
I should be able to finish up this week, as long as nothing comes up. Took a day off of it and will be ready to start again tomorrow night. I will have to take it to work to weigh, I don't have a scale at home. Need to make the firewall, seal the rest of the fuse, and be ready for the power plant at that point. Paint it while I wait for the motor and stuff. We shall see...
Got as far as I can right now with what I have... Taking it to work tomorrow to get a weight on it and see what I have.
Firewall is in, electronics are there with the exception of the motor, battery, and ESC.
I will post a weight once I have it.
Then get an order in to Grayson Hobby!
Firewall is in, electronics are there with the exception of the motor, battery, and ESC.
I will post a weight once I have it.
Then get an order in to Grayson Hobby!
Are the leading edges of your wing square edged? I noticed on the funbat where they made the leading edge, they taped the spot where the leading edge would be and folded it over to get the top piece. By taping it they made a nice round edge by compressing the foam and keeping it from tearing. I feel that a square leading edge will not perform the way you are hoping. It's going to take much more power and fly like a profile with a flat wing unless you can get some sort of smooth airflow over the airfoil. I'm sure it would fly but at a high angle of attack, may not generate lift in level flight.
Well, I was going for the same airfoil that Chad made for the Cessna that Josh B and Josh S did in the airfoil episode. If I need to add a round strip of foam to the leading edge of the wing I will. Just wanting to see how it reacts the way it is and improve from there. I know you are right about the square leading edge, but we will fly it anyway!
Thanks AK Flyer, I will keep updating as I go!
Thanks AK Flyer, I will keep updating as I go!
I stole some servos out of an old Cessna 182 I bought from Craigslist, it came with a 72 mhz rx and tx. I am going to get a few orange rx's from Hobbyking.
If you look earlier in the thread, I did show the ailerons working on the wing. (Post #22)
Once I get the electronics, motor and everything, I will post the maiden!
Last edited:
Its all good, I am sure you guys are as excited for me to get it in the air as I am. I am thinking you are right, I should get some soft foam like the noodles and round out my leading edges. Hmmmmmm, if I get a little more power in the motor, it won't matter if there is more weight, just won't be the slowest flyer... We shall see.
Can you put a half round on the front and save some weight? You may even try just shaping and taping. Power equals flight, but like you said it's about the speed required to maintain it. If you have a lot of elevator throw and enough power you can always slow it down in a high alpha lol.
Okay I have the weight... Not happy with it. The KF airfoil added a lot of weight to this plane. 630 grams (23oz) with servos and temporary rx.
No battery, motor, or ESC yet.
With this kind of weight, I am thinking about going to this motor and ESC:
http://www.graysonhobby.com/catalog/480500brushlessoutrunnermotorescgh2217series-p-337.html
GH2217-06
Grayson Hobby 30A ESC (included)
Trying to figure out the battery for this combo... The battery part is confusing according to the specs on this motor.
Any ideas?
No battery, motor, or ESC yet.
With this kind of weight, I am thinking about going to this motor and ESC:
http://www.graysonhobby.com/catalog/480500brushlessoutrunnermotorescgh2217series-p-337.html
GH2217-06
Grayson Hobby 30A ESC (included)
Trying to figure out the battery for this combo... The battery part is confusing according to the specs on this motor.
Any ideas?
Just thinking about the weight, I wonder if you could get the same effect without having a full sheet in the middle. Have a top and bottom, and have the front and back of the center piece but leave out the center, with maybe a rib in the center. I know it's not far from making ribs and spars, but I am curious how much weight you could save. I am going to have to try this airfoil myself, it's very intriguing.
I think that motor would do fine. I was confused a bit by it as well. It looks like they recommend a 2 or 4 cell for higher thrust, and a 3 cell for a little bit less. It sounds a bit odd. I would go with a 3 cell because I like the power, it's a good rpm range and the batteries are cheaper than a 4 cell.
I think that combo with a 1300 3 cell will do fine. I would go with a higher C rated battery, at least 25 in case you end up needing a lot of amperage to make it fly the way you want.
I think that motor would do fine. I was confused a bit by it as well. It looks like they recommend a 2 or 4 cell for higher thrust, and a 3 cell for a little bit less. It sounds a bit odd. I would go with a 3 cell because I like the power, it's a good rpm range and the batteries are cheaper than a 4 cell.
I think that combo with a 1300 3 cell will do fine. I would go with a higher C rated battery, at least 25 in case you end up needing a lot of amperage to make it fly the way you want.
A 1300 battery is 119 grams, the motor is 70 grams and the esc is 22 grams. Total weight 841 plus any connectors, the prop itself etc. Landing gear if you add it. Basically 30 oz or almost two pounds. I think the 35 ounce 3S setup would work fine. It should technically hover the plane with a full battery. Normal flight should be easy. I would start there and see how it handles the weight, then you could always step up the battery size from there for run time.
Does that sound right? I think having more thrust than weight should make it plenty powerful. Opinions?
Does that sound right? I think having more thrust than weight should make it plenty powerful. Opinions?
I was wondering about that myself... Maybe 2 ribs offset of each other just to get it a little more rigid, as the way this wing sits right now, I think I could almost stand on it!
I was thinking of a 25C and at least a 2200 mAh 3 cell for some great flight time but the specs confused me greatly as I am so new to picking motor battery combos. Isn't that all I will gain is more flight time, and a little more weight? If so, I think I will order this motor and look at HK for batteries, maybe nitroplanes not sure.
As always, thanks for the input AK, you have been a huge help.
(Oh I have some small weather stripping that is foam I could use for the leading edge that is round I think would work great.)
I am always choosing the lightest setup for many reasons. A shorter flight time is no problems for me. I am (almost) never using all the battery capaicity. If i am flying pattern then it is not easy to be fully concentrated for more than 5 minutes. I never fly pylon (= full throttle all the time). It is better to land and replace a battery to a new fully charged than carry a lot of dead weight. My choise of battery to a plane that size is normally : http://www.hobbyking.com/hobbyking/store/__11899__Turnigy_nano_tech_850mah_3S_25_40C_Lipo_Pack.html.
The supplied connector is crap if you need 25A so i go for the http://www.hobbyking.com/hobbyking/...0_Connectors_Male_Female_5_pairs_GENUINE.html.
The supplied connector is crap if you need 25A so i go for the http://www.hobbyking.com/hobbyking/...0_Connectors_Male_Female_5_pairs_GENUINE.html.
I've got some of the 2200's and they are considerably heavier than a 1300. The 2200 is listed as 204 versus the 1300's 119. Twice the weight. All you gain with higher mah is more run time. I can fly my supercub for 14 minutes on a 1300 with a brushed motor, and with my 480 motor and the 2200 battery I was easily flying for half an hour. I think with the motor package you listed and a 1300 that a ten minute flight would be easy.
For the wing, I'm thinking of several ideas. The first is to try it with only the first two layers. Save a ton of weight and see what kind of lift you get out of it. You could make a leading edge easier.
Then try the three layer wing with a hollow center layer using strips on the ends and maybe a center strip to hold shape then the top layer. I wouldn't make shaped ribs though, just to keep with the type of airfoil.
Before adding any more weight, I would look into shaping the leading edge on it's own unless the foam you are using is rigid enough to hold the shape you want. You might be able to use clear packing tape to compress the foam into a rounded edge without cutting it but it would be difficult to have an even shape from the root to the tip.
I would just use clear packing tape to hold the weatherstrip foam to the wing and this will reinforce the edge in case of a crash. Plus you can take it off easy if you want to change or replace it.
I am no expert but always happy to offer an opinion. I hope other people will chime in and help us all learn more about it.
For the wing, I'm thinking of several ideas. The first is to try it with only the first two layers. Save a ton of weight and see what kind of lift you get out of it. You could make a leading edge easier.
Then try the three layer wing with a hollow center layer using strips on the ends and maybe a center strip to hold shape then the top layer. I wouldn't make shaped ribs though, just to keep with the type of airfoil.
Before adding any more weight, I would look into shaping the leading edge on it's own unless the foam you are using is rigid enough to hold the shape you want. You might be able to use clear packing tape to compress the foam into a rounded edge without cutting it but it would be difficult to have an even shape from the root to the tip.
I would just use clear packing tape to hold the weatherstrip foam to the wing and this will reinforce the edge in case of a crash. Plus you can take it off easy if you want to change or replace it.
I am no expert but always happy to offer an opinion. I hope other people will chime in and help us all learn more about it.
You are absolutely right. Solid wings are not stronger than hollow.
If you just take a 1/2" strip 1/3 rd of the length from the front of the upper sheet an bend the upper sheet to a profile you will probably get the same strength or better.
I agree that the stock connector there is junk. If you step up to the higher C rated battery though, for a few bucks more it comes with a really good connector.
http://www.hobbyking.com/hobbyking/store/__18203__Turnigy_nano_tech_850mAh_3S_45_90C_Lipo_Pack.html
Or, for a 35C battery you can go with a standard turningy 800 mah with the good connector.
http://www.hobbyking.com/hobbyking/store/__18850__Turnigy_800mAh_3S_35C_Lipo_Pack.html
I personally would like the flight time of the 1300 but that's what I'm really familiar with. Less weight is always better though.
