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Pburts 2nd Contest Entry, BD-5

Old 10-17-2008, 05:13 PM
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pburt1975
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Default Pburts 2nd Contest Entry, BD-5




James, James? Are you there 007??? Seems we've run into some issues on the car, you'll have to take the jet!

Just as soon as its done being built

Not building a profile plane this time and still trying to work out the drawings to get formers in the right spots.
Formers will be glued onto a 1/4" dowel as the center line
The model being designed will have a wing span of 34"
Im not an EDF guy, so this will be a pusher design with a 2408-21 stuck on the back, hidden in the jet port (somewhat).
Its going on 3s, so I'll take any prop suggestions you got for speed.

Not sure either on if this will just have a flat profile wing, a KF airfoil or a standard airfoil. Flat will be the easiest but will require exposed carbon to stiffen it up. KF sounds interesting but I dont know to much about it.
Heck, I'll take suggestions on that too

Anyway, this build will start following the Yak 50.

Pburt
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Old 10-17-2008, 05:48 PM
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Drawings still being designed but here's the early stages.

Again, wingspan is 34" and overall length is 28"
Wing area is 1.37sqft and I'll have to keep weight below 20g for the 2408 to stand a chance.

really need a set of scales , end weight is always an unknown here...
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Old 10-17-2008, 06:54 PM
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Rabbitcreekok
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Pburt, don't forget that the original BD-5 was not a jet. It was a pusher, propeller driven airplane.

The BD-5 site should give you some help.
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Old 10-17-2008, 07:23 PM
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Thanks RC, you're right, it was a pusher but the Bond one (which I'll be marking this one up as) was the jet version. But you know, Im still open to EDF donations, lol.
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Old 10-17-2008, 07:52 PM
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Gee, pburt, from the drawing, I think that would make a cool profile plane as well......
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Old 10-17-2008, 08:13 PM
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Originally Posted by gfdengine204 View Post
Gee, pburt, from the drawing, I think that would make a cool profile plane as well......
lol, I'll leave that one for you . Want me to mail ya some drawings when its done? hehe
This one has a few more things to figure out tho, or I'd have .dwg file up already. will have to build and adjust. should be fun.

Decided Im going to go with a KFm step on top of the wing at 40% chord, rounded LE. Maybe I can conceal a way to remove the wings in the step? would really like the wings to be removable
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Old 10-17-2008, 08:24 PM
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Originally Posted by pburt1975 View Post
lol, I'll leave that one for you . Want me to mail ya some drawings when its done? hehe
This one has a few more things to figure out tho, or I'd have .dwg file up already. will have to build and adjust. should be fun.

Decided Im going to go with a KFm step on top of the wing at 40% chord, rounded LE. Maybe I can conceal a way to remove the wings in the step? would really like the wings to be removable
Why not make the wings hinged like the Bond version?
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Old 10-17-2008, 10:13 PM
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Originally Posted by gfdengine204 View Post
Why not make the wings hinged like the Bond version?
uhhh NO, lol.. Im thinking a dowel or carbon fiber shaft at the step that will be attached to the wing and stick into the fuse. At the back of the wing I'll do a screw attachment.

I printed the formers out, the rudder section and the center section for the wings. That'll be enough I can dry fit the important parts and see how its shaping out. maybe wrap it in paper to get my patterns started too..

Have a good weekend all!
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Old 10-17-2008, 11:49 PM
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pburt1975,

If you want to have plug-in wings go to WalMart and check out the carbon fiber and the alum. arrows in the sporting good dept. I have found some just the right size for the CB shaft to fit in the Alum. shaft. Put a section of the alum. in the fuse and a section of the CB in the wing with a stub beyond the root panel and you're in business. With the right series of 2408-21 you might get lucky enough that you can place the motor deeper in the fuse and still have enough shaft length for the prop to be in the correct position. As I remember them, the BD5's had a tube hub for the prop shaft about the same length as the outlet nozzle of the BD5-J. After all, once the plane is traveling at 60 to 70 mph you can not see the prop. Chellie has a lot of experence with that motor in pusher mode and can give you some good input on props for speed. Right off hand I think she has had good results with 5x6 or so sizes. where ya at Chellie?
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Old 10-18-2008, 01:03 AM
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Thanks Prof, .

I did some checking on another forum and found that these planes need some upthrust in the motor. 3-5 deg seemed the range, but at least one person said 3deg was not enough under full power, 5 seemed to fix that. Thing is, Im starting to wonder if using this KFm airfoil is going to cause enough lift to counteract it? I'll be using the second variation, but with the step further forward to keep the CG close to where it should be.
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Old 10-18-2008, 02:05 PM
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Now that's one I can not help with. I have not as yet used one of the KFm airfoils. I can see that kind of thrust angle with a flat bottomed (Clark"Y") airfoil. Seems it would be a lot if a symetrical wing was used. With symetrical wing the angel of attack has lot of influence on the lift produced. I guess you'll have to just experement with it and let us know your results.

Charlie
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Old 10-19-2008, 01:42 AM
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Originally Posted by proffcharlie View Post
pburt1975,

If you want to have plug-in wings go to WalMart and check out the carbon fiber and the alum. arrows in the sporting good dept. I have found some just the right size for the CB shaft to fit in the Alum. shaft. Put a section of the alum. in the fuse and a section of the CB in the wing with a stub beyond the root panel and you're in business. With the right series of 2408-21 you might get lucky enough that you can place the motor deeper in the fuse and still have enough shaft length for the prop to be in the correct position. As I remember them, the BD5's had a tube hub for the prop shaft about the same length as the outlet nozzle of the BD5-J. After all, once the plane is traveling at 60 to 70 mph you can not see the prop. Chellie has a lot of experence with that motor in pusher mode and can give you some good input on props for speed. Right off hand I think she has had good results with 5x6 or so sizes. where ya at Chellie?
Hi Charlie Your very close, I have had the best luck with a 7x6 sf prop, cut down to a 6x6 sf with a 30 amp esc on a 2408-21, it gives about the best thrust to speed for bp21 motor, here is a delta with that set up, Take care, Chellie

[media]http://www.youtube.com/watch?v=lgLfXZamiHw&feature=user[/media]



http://www.youtube.com/watch?v=mwBEuxIkZY4
i removed the 2409-12 and installed the 2408-21, it works better the 2409-12 is amp hungry
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Old 10-19-2008, 02:47 AM
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Originally Posted by CHELLIE View Post
Hi Charlie Your very close, I have had the best luck with a 7x6 sf prop, cut down to a 6x6 sf with a 30 amp esc on a 2408-21
Thanks Chellie and Prof. Chellie, did you use the 30 amp because you had to, or because it was what you had handy? BP-21 is only good for like 14 amps right? Oh, the cut down prop, just a standard orange sf prop? or is there a 'pusher prop' to use? sorry, I should know this stuff but just dont trust my gut answer yet.


Strung the formers together on a carbon shaft today for an eyeball. Things line up pretty good but I forgot the template for the formers locations, so it was really just an eyeball....
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Old 10-19-2008, 02:53 AM
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Originally Posted by pburt1975 View Post
Thanks Chellie and Prof. Chellie, did you use the 30 amp because you had to, or because it was what you had handy? BP-21 is only good for like 14 amps right? Oh, the cut down prop, just a standard orange sf prop? or is there a 'pusher prop' to use? sorry, I should know this stuff but just dont trust my gut answer yet.


Strung the formers together on a carbon shaft today for an eyeball. Things line up pretty good but I forgot the template for the formers locations, so it was really just an eyeball....
Hi, I always use a 25 to 30 amp ESC on all of my bell motors, they dont get hot, and last forever, as long as you prop the motor not to exceed the maximum amps, your fine using a larger ESC, Take care, Chellie
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Old 10-20-2008, 09:44 PM
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Originally Posted by CHELLIE View Post
Hi, I always use a 25 to 30 amp ESC on all of my bell motors, they dont get hot, and last forever, as long as you prop the motor not to exceed the maximum amps, your fine using a larger ESC, Take care, Chellie
Do you still need a BEC on 4 servos with those 25-30 amp ESC's?


Update on the drawings. These will be getting printed soon and then the build will start.

So far, Im having a real issue with the Rudder and its servo. Im starting to think its not needed, because its just going to be a PITA to route the linkage. Im sure there's a way but my limited experience aint showing me nuttin yet.

No idea where components are going yet, Im going to need the airframe about finished so I can get the balance point some where close.
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Old 10-21-2008, 05:24 AM
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Originally Posted by pburt1975 View Post
Do you still need a BEC on 4 servos with those 25-30 amp ESC's?


Update on the drawings. These will be getting printed soon and then the build will start.

So far, Im having a real issue with the Rudder and its servo. Im starting to think its not needed, because its just going to be a PITA to route the linkage. Im sure there's a way but my limited experience aint showing me nuttin yet.

No idea where components are going yet, Im going to need the airframe about finished so I can get the balance point some where close.
I Know your going to think this is a overkill but here is a nice ESC to use with 4 servos, it has a 3 amp BEC, its a 40 amp, turnigy, dont worry about the higher rating on the ESC, as long as your motor and prop are matched for a given amp draw, you are fine using a larger ESC, The Extra amp rating is just going along for the ride and you will be able to use this ESC on a lot of other projects, if your going to use a 25 to 30 amp esc, yes get a UBEC, the towerpro ESC in this range are only rated at a 1.5 amps bec, not enough for 4 servos, hope that helps, Chellie

http://www.hobbycity.com/hobbycity/s...eed_Controller
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Old 10-21-2008, 05:27 AM
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some prop and amp draw Data, from Heads up Rc.
http://www.headsuprc.com/servlet/the...lectric/Detail

Some experienced flyers who post on the 'Wattflyer' forums suggest using a little 'JB Weld for metal' to secure the aluminum stick mount to the motor tube. This prevents it from working loose and spinning in the mount. Be very careful not to get any on the shaft and bearing though.
Recommended props for 3 cell Lipo batteries:
GWS props fit the 3mm shaft on this motor perfectly - no adapter needed. APC and Master Airscrew props require a prop adapter or prop saver for a 3mm shaft (available in my store).
The GWS EP8040 is the most commonly used prop with this motor. It will produce about 22 ounces of thrust at 14 amps with a pitch speed of 43 mph. This motor is only rated for 13 amps, so you need to provide for plenty of airflow over the motor and use full throttle sparingly until your Lipo has discharged somewhat.
The APC 8x4E produces 22 ounces of thrust at 14 amps with a pitch speed of 39 mph. The same caution must be used as with the GWS EP8040.
I do not recommend using any other 8 inch props with this motor when using a 3-cell Lipo.
The TP 7x5E produces 20 ounces of thrust at 14 amps with a pitch speed of 54 mph. The same caution must be used as with the GWS EP8040.
The APC 7x5E produces 20 ounces of thrust at 14 amps with a pitch speed of 54 mph. The same caution must be used as with the GWS EP8040.
The GWS EP7035 produces 16 ounces of thrust at 9 ampswith a pitch speed of 47 mph.
The APC 6x5.5E produces 11 ounces of thrust at 10 ampswith a pitch speed of 65 mph.
The Master Airscrew 7x4 3-blade produces 15 ounces of thrust at 12.5 ampswith a pitch speed of 43 mph.
The Master Airscrew 6x4 3-blade produces 11 ounces of thrust at 9.5 ampswith a pitch speed of 48 mph.
Recommended props for 2 cell Lipo batteries:
The GWS EP1060 prop produces about 15 ounces of thrust at 11.5 amps with a pitch speed of 33 mph.
The GWS EP1047 prop produces about 15 ounces of thrust at 12.5 amps with a pitch speed of 24 mph.
The APC 9x3.8SF prop produces about 16 ounces of thrust at 11.5 amps with a pitch speed of 24 mph.
The GWS EP9047 prop produces about 14 ounces of thrust at 10.5 amps with a pitch speed of 27 mph.
The GWS EP9050 prop produces about 14 ounces of thrust at 10 amps with a pitch speed of 32 mph.
The GWS EP9070 prop produces about 13 ounces of thrust at 12.5 amps with a pitch speed of 35 mph.
The GWS EP8040 prop produces about 12 ounces of thrust at 7.5 amps with a pitch speed of 32 mph.
The GWS EP8043 prop produces about 12.5 ounces of thrust at 8 amps with a pitch speed of 31 mph.
The GWS EP8060 prop produces about 13 ounces of thrust at 10 amps with a pitch speed of 39 mph.
The GWS HD8060 prop produces about 12 ounces of thrust at 9 amps with a pitch speed of 41 mph.
The above data is a result of my own testing using fully charged Lipo batteries.
2408-21 Specifications:


Weight = 1.6 ounces (46 grams)

Diameter = 1.2 inch (31mm)
Total Length = 2.4 inches (62mm)
Shaft Length = 1.2 inches (31mm)
Shaft Diameter = 3mm (GWS Props fit nicely)
Voltage = 7.2 to 12.6
KV = 1600
Current = 13 amp max.
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Old 10-21-2008, 02:57 PM
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Thanks again Chellie, looks like I have to build light!! Anything with enough thrust has the motor over amped. FYI, Im expecting this build to come in around 16-18oz. pretty wide range, but thats the best I can guestimate right now.

Considering the cost, thats not overkill at all. A 20amp cheap esc is 15 bucks and another 10-20 for the BEC as well... That ESC covers all that pretty well, I wouldn't need to worry with soldering in the BEC and all. Its on the list following "Money for RC stuff "
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Old 10-24-2008, 04:57 PM
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Ok, the plane now at least exist on paper. Man this fuse size compared to the wing is shocking to see in scale.
I'll get a start on it this weekend, post progress pics as we go..

Considering weight concerns, I MAY have to size it down a little more, so the planned power system can move it...
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Old 10-29-2008, 03:04 PM
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Well, weekend didn't go as planned and now Im starting to stack up some projects. Gonna see if my son feels like cutting some of this out, but so far he's not a big fan of the plane. Like I told him, "thats cool you dont have to fly it "
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