RE: E-Flite F-15 Eagle
 

You ppl. are dropping waaaayyyy to much cash into a foamy jet.! I have a composite T-45 GOSHAWK w/single EDF that will fly circles around that expencive/heavy piece of foam for 1/2 the cash. ELECTRIC JET FACTORY.comTalk to Robert & tell'em "Dogg" sent ya...!

RE: E-Flite F-15 Eagle
 

No retracts.. nothing worse than a jet with dangly wheels..

RE: E-Flite F-15 Eagle
 

right on lol i have the retracts now just got them installed starting to love the eflite f15 :D

RE: E-Flite F-15 Eagle
 

also i need help do i conntect both esc to the resever and keep both power cabels connected as it has 8 servoes does it need power from both esc or just one can it blow the resever?!

RE: E-Flite F-15 Eagle
 

Yes - make up a double Y cable to connect both packs to each other and then to both ESCs. Plug both ESCs into a (HD) Y then into the Rx.
Works well.

RE: E-Flite F-15 Eagle
 

ok thanks

RE: E-Flite F-15 Eagle
 

I agree.....!

RE: E-Flite F-15 Eagle
 

I am looking for a pair of motors that I can drop right in to replace the stock called for motors to really make this thing scream. Please, if anyone out there has an idea please let me know!!!!! Thanks!

PS I am also changing paint schemes. I have been told that Tamaya paints always do a great job on foam and stick great as well.

ndf

RE: E-Flite F-15 Eagle
 

Hey all,

I am looking for a pair of motor to drop into the F-15 that will go with the included fans and make the thing a very good performing jet with good vertical and a bit of flat out speed? I have 3s 2200mah 20 batteries and the stock fans that came with the kit. Any advice? Thanks for the help!

ndf

RE: E-Flite F-15 Eagle
 

well i would say u need 4800kv motors minium i have 3800kv and there not as powerfull as i want out of a jet and the fan units that come with it seems good

RE: E-Flite F-15 Eagle
 

I need some advice for upgrade motors in this bird. Any help out there?

ndf

RE: E-Flite F-15 Eagle
 

like i sead some 4200kv would work as longs as there the same size as the 3800kv ones

RE: E-Flite F-15 Eagle
 

ndfanatix,

On the previous page Billdor mentioned that he used Don's RC wicked 4800 Kv motor. http://donsrc.com/cart/index.php?act...d&productId=52

I've emailed Billdor to see if we can learn from his experience. If he doesn't post here, I will let you know what he says.

Charlie

RE: E-Flite F-15 Eagle
 

Hi NDF et al.,

I corresponded w/ BillDor regarding his Don's RC wicked 4800 Kv motors in his F-15. He said he was disappointed in the performance, since he was hoping for 100 mph speeds and the actual were around 60-70 mph. He noted that he had plenty of thrust but too little speed. Reminds me of having a long prop with a small blade pitch. Apparently he is trying to find a way to better manage the discharge to increase the output. In his email he said, "From what I have been hearing it helps if you put a tube on the back of the fan to reduce the discharge area to equal the fan swept area (FSA). This is the area of the fan minus the area of the hub." I'm not exactly sure what that means, but it sounds like there may be some good science behind this. If anyone knows a link further describing this, that would be helpful.

Something I liked about Don's RC is a Pentium 40A ESC they make and sell for about $40. They've also come out w/ a new extreme 5400 Kv motor (http://donsrc.com/cart/index.php?act...d&productId=50), but I was unclear how well it would work with the F-15.

Charlie

RE: E-Flite F-15 Eagle
 

You might want to check this test of the F15 with reduced exhaust cones:

http://www.youtube.com/watch?v=GKHkxJPsSPY

I'm really enjoying my F15 now. I'm back on stock motors after destroying a fan with higher KV motors.
The big difference was going with 2 x 4S. It now does 139 KPH in level flight and has excellent vertical perf.

See:

http://www.youtube.com/watch?v=aEKr8BZjb0E

RE: E-Flite F-15 Eagle
 

Wow Patrick... great videos, science, and flying!!! Thanks so much for providing that valuable information.

It sounds like the four cells made a big difference. It looks smokin hot in the video.

Question about the thrust video: I understand how the cones had a slight reduction in thrust but substantial increase in velocity leaving the engine, but what does that mean? Isn't thrust the bottom line? Or would the increase in exhaust velocity improve speed? Or does none of it matter since increasing the batteries to 4 cells seems to make the biggest difference?

Any thoughts of your would be appreciated!

Thanks so much,

Charlie

RE: E-Flite F-15 Eagle
 

Charlie

From what I understand thrust versus velocity is the same thing as diameter versus pitch on a prop. more velocity and less thrust will generally give you more speed (within limits of course) If you run out of thrust it will take forever to get up to speed and launches will get very difficult. On the other hand you can have all kinds of thrust but without velocity you will not have any speed. Have you ever seen a prop driven plane with a very large diameter fine pitch prop? It will pull a bench accross the yard but will never attain enough speed to get off the ground.

Bill

RE: E-Flite F-15 Eagle
 

The Eflite F-15 is a big airframe. To get 100 mph will require 1000 watts or so. I have not measured the outlet area on the F-15 but in general on my EDF models I use an 80-85% FSA nozzle. This reduces static thrust but increases efflux speed which means more top end speed. Since this uses a SF fan the correct outlet would be 2" diameter.

Don

RE: E-Flite F-15 Eagle
 

The specs for the stock motors from horizon are that they are 3800kv and are only rated for 3s batteries. Are these the ones you are using? Thanks

RE: E-Flite F-15 Eagle
 

Yes. Standard and rated for 3S.
Just be careful
:-)

If you go this route, definitely use a BEC and preferably bigger ESCs. 40A static - probaly a little less once it gets going.
6 blades too

RE: E-Flite F-15 Eagle
 

I really appreciate Patrick, Don's, Bill's, etc. thoughts on this!!! After attempting to follow the forum, it seems the collective knowledge to date is as follows:

- Stock motors (3800 Kv), 6 blade fan (stock), and 3s batteries provides lack luster performance (several folks)
- Don's wicked 4800 Kv motor, 3 blade fan (stock less 3), and 3s batteries provide ok performance (Billdor)
- Stock motors (3800 Kv), 6 blade fan, and 4s batteries provide strong performance - best to date (Patrick)
- Attaching exhaust ports that reduce the nozzle to 2" should increase the aircraft speed (Patrick & Don)

If anyone else has any experiences or trials they would like to share, that would be great.

I would also appreciate hearing Don's recommendation for a motor (4000, 4800, 5400), # of blades, and battery type for the F-15. He seems to have done extensive tests in general and sells strong motors at a good prices (donsrc.com).

Thank you all,

Charlie

RE: E-Flite F-15 Eagle
 

Charlie,

On the SF fan I would not use the Wicked 5400, too many amps, that motor is suited more for smaller fans that need the higher rpm. The Wicked 4000 on 4S and 3 bladed SF fan is about 450-500 watts per fan. Hyperdyne has that in his F-15 and runs two 4S lipos packs. The thing to remember is that watts required is a function of speed cubed. To go from 80 mph to 100 mph requires twice the watts. That is why adding lots of power to these airframes results in moderate speed gains. Personally for me if I owned this plane I would probaby go with the Wicked 4800 on 3S and 3 blade rotor, reduce the nozzles and accept the plane as what it is. I have a GWS F-15 I have the Wicked 4800s in the GWS EDF 64 rotors. I clipped the wings 2" each to make the span smaller and more scale. The AUW is about 48oz with two 3S 2200 but the thrust is about 52 ounces. Speed is about the same as the Eflite model on the same 4800 motors, like 70-75 mph. I know that adding more power is kind of a waste as the speed will not go up too much. So I fly it as it is. If you want a fast EDF jet you need to go to the Alfa models, the HP F-16, or the Electrifly L-39 to get good speed on a single 2200 mah lipo. They are smaller and less draggy so they go over 100 mph easily on a 4S pack, and in the 90s on a 3S 2100. I tend to stick to the smaller jets as the bigger ones need lots of watts to go fast and have big lipos and are hard to hand launch.


Don

RE: E-Flite F-15 Eagle
 

Better check your math there, if speed was a function of Watts cubed (Speed=K*Watts^3) then you'd only need a 7.7% increase in power to go from 80 to 100 mph. I believe you mean the watts are a function of the speed cubed (Speed^3=K*Watts), or the speed is a function of the cube root of Watts [Speed=(K*Watts)^(1/3)].

RE: E-Flite F-15 Eagle
 

Fixed my typo.

Don

RE: E-Flite F-15 Eagle
 

Don,

I really appreciate your thoughts and comments... very helpful!!!

If you or anyone can help explain how reducing the blades from 6 to 3 helps improve the performance, I would enjoy hearing it. The only thing I can guess is that the motor is allowed to spin faster with 3 blades thus moving more air than the 6 blades. Is it something like that?

Thanks again,

Charlie