F-100 Super Sabre 1/8th Build (70")
- Thread starter thenated0g
- Start date
Looks awesome! She looks like she wants to fly.
On edit... what prop are you thinking of using again? I saw an early post about a 16x10, but for a pusher jet you way want to look for smaller and more pitch. A 12x12 or a 14x14 perhaps. Just a thought.
On edit... what prop are you thinking of using again? I saw an early post about a 16x10, but for a pusher jet you way want to look for smaller and more pitch. A 12x12 or a 14x14 perhaps. Just a thought.
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The max suggested prop is a 16x10 on the emax prop data, will attach it below. Its the 470kv motor on 6s. I have a 15x12 that picked up but i need to see if it hits the max amps of 65.
also depending on how rough the prop takes the landing i may switch to a folding setup.
Gotcha. I know you're looking at bungee launching, and that's a good idea. I've been caught by a larger prop on a pusher jet before and its no fun. Since then I tend to run smaller, steeper props on pusher setups. A general rule I've found is that you can increase prop pitch by an inch by reducing length by 1 - 1.5". Definitely need to do amp and thrust tests, but its a thought. Looking forward to seeing her fly!
Yes im am right at 1:1 thrust to weight so i can definately switch to a higher pitch prop without worrying about having enough thrust. At my rpms and the 10 pitch i think i calculated it at around 60mph, well above my stall speed of around 20mph, but it would be nice to have a little more speed. The problem with my 15x12 is that its for a gasser, which means its pretty thick and heavy plastic. I may just use the 16x10, see how it is, and than order a few more sizes to try. Assuming its still in one piece 
Do you have any opinion on using a gas prop on an electric motor?
I'd rather go with an electric prop if its an option, but I've run gas props on electric setups before. They are generally just more heavily built to handle the vibrations of IC engines. Because of that they have more mass for a given prop and probably a thicker airfoil as well. In a pinch I'd have no problem running a gasser prop on an electric, but would NOT go the other way.
Couple years back when i spun these up for the first time on the 200% guinea pig....yikes that is terrifying. I need to strap this thing down good and get some personal protective gear lol. Mainly just to make sure it will not shake the motor off the mount. I will get a video up by this weekend probably with the prop on. I need to get the 150a smart sensor dialed into the taranis and make sure it is matching my multimeter and just do some fine tuning on the servo throws....oh and CG...CG yeah.Oh come on man, what kind of weak sauce run up was that? I expected to see all that equipment blown out of the window and all I get is some little 1% throttle blips.
j/k
Seriously though, that is going to look great in the air.
Went thru and measured everything. Here is the results from two different calculators on line.
Finally was able to get a picture with it all put together. Full size human for reference
Based on those calculations above, saying CG between 14.5"-15.5" i balanced it at 15" back from leading edge, added some lead on the nose until it balanced, and it looks like flying weight with one 5,200mah 6s battery is going to be around 5.3kg or 11.7lbs. This is totally doable with this motor putting out 5.1kg. My guinea pig had 2 of these motors and weighed 39lb, which is 19.5lbs per motor, so this is almost half that weight. If that makes sense.
Here is the 16x10 prop on the back to show airflow. Probably be noisy with that square end of the fuselage. Originally i had planned to put a cone around the motor. May still do that.
Based on those calculations above, saying CG between 14.5"-15.5" i balanced it at 15" back from leading edge, added some lead on the nose until it balanced, and it looks like flying weight with one 5,200mah 6s battery is going to be around 5.3kg or 11.7lbs. This is totally doable with this motor putting out 5.1kg. My guinea pig had 2 of these motors and weighed 39lb, which is 19.5lbs per motor, so this is almost half that weight. If that makes sense.
Here is the 16x10 prop on the back to show airflow. Probably be noisy with that square end of the fuselage. Originally i had planned to put a cone around the motor. May still do that.
Finally was able to get a picture with it all put together. Full size human for reference
That plane looks huge!! Are you sure the reference human is full size?
a little larger than normal...in some areasThat plane looks huge!! Are you sure the reference human is full size?
It would be worth the drive, but i dont like being away from my family that long. Maybe when my daughter is older i can get her into it.
just caught up on the thread. This is a great project! I think more importantly, this project uses and illustrate beautifully, some alternative inexpensive techniques that those masters of FT foam technique can learn from and use to make the next inspired project.
Superb Nate. I'm with the other followers, can't wait to see this take off. Keep at it, and good Luck!
Superb Nate. I'm with the other followers, can't wait to see this take off. Keep at it, and good Luck!
Yeah foamydm, its pretty cheap stuff. I can get a 8x4 foot 2 inch thick sheet of foam for $19 from homedepot. That is enough to cut out 10x specwings for instance. That makes them $2 each in foam. You still need to add kite rods or wood for stiffness and than cover it in packing tape or laminate, but pretty cheap.
Project not dead!
I have been really distracted with my CNC hot wire cutter and have been waiting on a few parts. I decided to make a bungee launcher as this will make a much shorter takeoff that i can use in more areas.
This is a version of what i have seen online that lots of others have made. My contribution is that instead of it having back legs it has a ground plate that will have ground screws. I feel this is a pretty large improvement over the other designs i have seen. In the other designs, when the sled "hits" the front or is stopped by a rope connected to the back, the effect is the same. All that force slams the entire unit forward. To stop the machine from jumping forward and collapsing there are usually some pins in the front to stop the legs from rotating. This is a lot of repeated force applied to two small areas of thin tubing. In my version the front legs have nothing stopping them from rotating. The back plate will be locked into the ground with 4 long screws, like the ones used for large dogs. The rope to stop the forward motion will be attached to this plate. So all force will be applied to the bottom plate and 4 screws.
The length of travel is 77 inches. I made up 2 bungees that have 12 inches of material in between the rings. When stretched to 77 inches (6 times there length as recommended by hobbyking) they each have a pull of 15lbs. So for the f-100 i will have 4 of them for 60lbs of pull throwing a 10lb plane. Of course before doing this i will be using a 10lb dummy weight and seeing what the thrown trajectory is like. At the moment i feel like the front end should be higher. This is easily accomplished by getting some wooden dowels or some kind of rods that can just insert into the legs.
All parts are rated at least 200lbs and usually are in the thousands of pound ratings.
I just received my snap shackle (last picture) that will be the release mechanism. It means i will be standing off to the side in case anything releases prematurely. It will also have an emergency lock that needs to be removed before the shackle will release.
The trolley is going to be setup so that different top plates can be attached depending on the size/type of plane being launched so i can use it for other stuff in the future.
Here is a playlist made on youtube of different launchers:
https://www.youtube.com/playlist?list=PLMieSP4Ym7qq3Nz1NjVfsoLUlxXVbRltJ
I have been really distracted with my CNC hot wire cutter and have been waiting on a few parts. I decided to make a bungee launcher as this will make a much shorter takeoff that i can use in more areas.
This is a version of what i have seen online that lots of others have made. My contribution is that instead of it having back legs it has a ground plate that will have ground screws. I feel this is a pretty large improvement over the other designs i have seen. In the other designs, when the sled "hits" the front or is stopped by a rope connected to the back, the effect is the same. All that force slams the entire unit forward. To stop the machine from jumping forward and collapsing there are usually some pins in the front to stop the legs from rotating. This is a lot of repeated force applied to two small areas of thin tubing. In my version the front legs have nothing stopping them from rotating. The back plate will be locked into the ground with 4 long screws, like the ones used for large dogs. The rope to stop the forward motion will be attached to this plate. So all force will be applied to the bottom plate and 4 screws.
The length of travel is 77 inches. I made up 2 bungees that have 12 inches of material in between the rings. When stretched to 77 inches (6 times there length as recommended by hobbyking) they each have a pull of 15lbs. So for the f-100 i will have 4 of them for 60lbs of pull throwing a 10lb plane. Of course before doing this i will be using a 10lb dummy weight and seeing what the thrown trajectory is like. At the moment i feel like the front end should be higher. This is easily accomplished by getting some wooden dowels or some kind of rods that can just insert into the legs.
All parts are rated at least 200lbs and usually are in the thousands of pound ratings.
I just received my snap shackle (last picture) that will be the release mechanism. It means i will be standing off to the side in case anything releases prematurely. It will also have an emergency lock that needs to be removed before the shackle will release.
The trolley is going to be setup so that different top plates can be attached depending on the size/type of plane being launched so i can use it for other stuff in the future.
Here is a playlist made on youtube of different launchers:
https://www.youtube.com/playlist?list=PLMieSP4Ym7qq3Nz1NjVfsoLUlxXVbRltJ
