F-4 Phantom - Twin 70mm EDF Monster!!
- Thread starter Mid7night
- Start date
Got mine built using UK foam board and it weighs 2.1kg with the edfs in a similar place to SOTM's build .
If anything mine is tail heavy with 2 X 2200 4s batteries up to the front landing gear.
What do other folks builds weigh including batteries ?
Fun build thanks for the plans ��
If anything mine is tail heavy with 2 X 2200 4s batteries up to the front landing gear.
What do other folks builds weigh including batteries ?
Fun build thanks for the plans ��
Sotm
Member
You're going to want more than 2200 mah per battery, EDFs eat the mahs 3000 will maybe give you two minutes. I'd use at 4000mah for each EDF. Once you change those out you should not be tail heavy then. BTW mine is 6 pounds AUW ready to fly. That's roughly 2.75 kgs. I am using 1 4S 6000mah battery for both and expect <2 minutes flight time at full throttle.
Make sure to calculate your CG position correctly and then check CG again. Here's a good on-line calculator.
https://rcplanes.online/cg_calc.htm
Use single panel and remember wingspan half is measured from the ducts out, not half of total span!! The area covered by ducts and fuselage does not produce lift!
here is my attempt at your F4 Ben. I have a huge amount of respect for you for being to design this beast. I have made a few mods.
the rubber band canopy attachment.
the removable wings, i had to reinforce the bottom of the inlets and of the fuselage.
edfs are much further back but I am using a 6s5000mah batt (no need for tail weight)
much larger landing gear because the larger wheels mean it can handle the grass runway better.
I also made thrust tube exhaust covers from foam board for durability.
I have yet to maiden it due to weather.lots of snow and rain here in the UK.
the rubber band canopy attachment.
the removable wings, i had to reinforce the bottom of the inlets and of the fuselage.
edfs are much further back but I am using a 6s5000mah batt (no need for tail weight)
much larger landing gear because the larger wheels mean it can handle the grass runway better.
I also made thrust tube exhaust covers from foam board for durability.
I have yet to maiden it due to weather.lots of snow and rain here in the UK.
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Glad you like it Ben, I thought building it was a challenge to but to be able to design this is an exceptional skill. (A twin 70mm series would go down very well 
) I wont put any colour on for the maiden but once that is out the way I'm going to paint it in the blue angels scheme. I prefer paint to tape and I always find the neatest paint jobs are the simplest, blue angels being only 2 colours was the simplest.
) I wont put any colour on for the maiden but once that is out the way I'm going to paint it in the blue angels scheme. I prefer paint to tape and I always find the neatest paint jobs are the simplest, blue angels being only 2 colours was the simplest.teddydbest
New member
Excellent job! it flies so nice! you should be proud.
Well mine goes !!!
Yes it was nose heavy even with the 2x 2200's in it. I know the 2200's are bad but I'm running the same power setup from my Viggen and X29.
I've been using the super cheap £5 70mm 6 blade edf and Turnigy 2226 motor from HKing, its nasty but makes good thrust and lowish vibes if you leave the cone off the end of the fan
Getting a reasonable flight time 2 mins plus and still some battery reserve after a few full bore passes.
It has come in at just over 2kg with batteries
Thanks again to Ben for the plans and the help from other builders on here !!
Now for a paint job USS Coral Sea I think
Sotm
Member
Another successful flight - AND LANDING - on my F-4.
My first attempt went very wrong. The flying stab was off in the up direction way too much and when it broke ground it went straight up! Tried very hard to get it under control but after about six porpoises I cut power and it nosed in. Wing survived but I am rebuilding the fuse right now. Going to put a wing incidence meter on both the wing and stab first this time with both at 0 degrees.
Duane
I've found mine is sensitive to the angle of the flying stab.
I've done my best to make sure the stab and wing are at 0 degrees.
I did follow Ben's advice and build with a traditional elevator 😉
I've also added bracing to stop the tail section flexing where it mounts to the fuselage.
Mine still leaps into the air fairly hard but it's controlable.
I've had think about the leaping into the air thing and done some research.
It could be something called pitch up where part of the wing stalls and moves the point at which lift is generated forwards ( center of pressure ), which amplifies the problem.
One solution is to add 'wing fences' to stop the air flowing sideways over the wing and direct the air flow from the front to the back of the wing .
Chuffed that this project has taught me some actual aeronautics 😁
Will try it as soon as our weather improves !
It could be something called pitch up where part of the wing stalls and moves the point at which lift is generated forwards ( center of pressure ), which amplifies the problem.
One solution is to add 'wing fences' to stop the air flowing sideways over the wing and direct the air flow from the front to the back of the wing .
Chuffed that this project has taught me some actual aeronautics 😁
Will try it as soon as our weather improves !
Grifflyer
WWII fanatic
After you download the plans linked in the first you have to do is open up the plans in adobe reader and select print. After the print window opens up there should be a section in the middle of the window labeled "Page Sizing & Handling" right below that there should be options to choose between "Size" "Poster" "Multiple" and "Booklet" You are going to want to select the "Poster" option. Next, ensure your tile scale is set to 100%, your overlap is set at 0.005 in. and that you have the "Tile only large pages" option selected. You can also select "Cut marks" which will make tiling the plans after they printed easier, but it will increase your page count from something like 8 to 12. Lastly, go down to the bottom of the print window and click print.
There aren't any dedicated build instructions, instead you can read through the thread and look at pictures of other peoples builds and work from there and if you run into a problem you can ask questions and people here will be happy to help you out.
Jermaine123
New member
So ..i finally maidened mine ..and it went horribly wrong .. I didn't use any landing gear ... Hand launched ... It went like straight up and lawn darted into the ground ......
