Official Freewing F/A-18C Hornet 90mm EDF Thread

[Mizer67]

The first picture is where I fly with these heavy (858 gram) long bricks, which are about the same dimensionally as your 6000's. It won't be exact given the weight difference and difference between planes, but might give you a place to check.

The MCB (Blue Box) wouldn't allow this normally, I relocated mine under the tray.

In the second picture, my CG location is approximately (finger tips) between the plastic attachment point for the wing and the panel line behind it and near where the factory applied too much glue in this photo.

My location is not super precise and also not super critical to being able to get to V(r) or V(rot) in this plane as long as you're not too far one direction or another.

[Madness]

This is my high rate throws. I think they are not that different from yours Mizer. Do you think I need more?

[Madness]

Madness that's very discouraging, sorry to hear it. There must be something way off. I have the original stock grey F-18 that I redid that ended up weighing about 1.2 extra POUNDS than the stock grey and I fly off of grass and she lifts off in 100 feet just fine. To make matters worse, mine has the original stock 9 blade 3748-1750 Kv outrunner, which Motion recently upgraded with the 9 blade 1900Kv inrunner (which I assume is in yours), so mine should be much less powerful than yours. I also have the 90 mm F-16, upgraded to the 12 blade 1835 Kv inrunner and my F-18 get's off in the same or even less distance. I'm using a RT 6250 mAh 35C battery in my F-18 (but the HRB 6000 50C in the F-16), which weighs in at 790 g and I fly it at a CG further back than the manual at around 97 mm (the furthest I can get it and some are flying at 110-120mm just fine). All I can recommend is to recheck the CG, get it to at least 94 mm from the recommended 88 mm and make sure that the battery you have has sufficient discharge capacity (C) to spool up the EDF to it's full potential. And keep in mind that just because a battery has a printed C of some number, that's definitely not what it really is. If you have a power meter, your EDF at full throttle on a fully charged battery (inrunner or outrunner) should be drawing somewhere around 117-120 Ah and 2600-2800 Watts. An inferior battery will be as much as 10-15% below that and will definitely affect the take-off. One last thing, with most EDF's, it helps to start the take-off run with full up elevator, thus relieving downward pressure on the nose gear and slowing it up on the take-off run (in grass it's even more pronounced). As it gets closer to lift off speed, you can relax the elevator so it doesn't shoot straight up and stall and you should then get a nice smooth take-off.

I will also tell you that in my case, I maidened it at 88 mm and it require a hell of a lot of up elevator trim to fly level, something like 5mm more than at the stock neutral location. If I remember, that was something like 50% up trim in the elevator.

Not sure any of this helps, and hope others with more knowledge than I have get to weigh in. Something definitely is holding your F-18 back. I suspect 1) not enough up elevator travel-neutral position not up enough & 2) not enough power from your battery.

My motor is the original 1750 outrunner, this is not the upgraded one. On my 2nd attempt to fly this plane I swapped the EDF and put the Hacker/Wemotec combo that I have on my 90mm F-16 (1850 KV inrunner 11 blades), faster take off speed, same outcome.

[Mizer67]

This is my high rate throws. I think they are not that different from yours Mizer. Do you think I need more?

That should be enough to get you airborne I'd think, but yes you could use a bit more if you're having trouble. The inside of my horizontal stabs at full deflection are above the thrust nozzles.

I'd move the CG back, add a few more mm of up trim vs. what you have dialed in now at rest on your stabs., double check the vent (a.k.a cheater) on the bottom of the plane is free of grass as well as the inside of the fan itself also (assuming you've been flying off of grass, otherwise disregard).

I have more throw, but not that much more and I don't usually fly on high rate unless I'm really wringing it out at lower speed and have never had trouble rotating.

Secondly, I'd try takeoff flaps. Dial in somewhere between 10 and 15 degrees of flaps for takeoff. It'll shorten your ground roll appreciably without adding too much unwanted drag. I add about a mm or two of up trim in my flap mix for T/O flaps. Without that minor adjustment, it creates a nose down pitch.

[Madness]

The first picture is where I fly with these heavy (858 gram) long bricks, which are about the same dimensionally as your 6000's. It won't be exact given the weight difference and difference between planes, but might give you a place to check.

The MCB (Blue Box) wouldn't allow this normally, I relocated mine under the tray.

In the second picture, my CG location is approximately (finger tips) between the plastic attachment point for the wing and the panel line behind it and near where the factory applied too much glue in this photo.

My location is not super precise and also not super critical to being able to get to V(r) or V(rot) in this plane as long as you're not too far one direction or another.

Wao! that's an eye opener! Yeap, mine is way front! I'll need to do that change for sure! Thanks a lot the picture!

As a matter of fact, thanks a lot everybody. You all been of super help in this very frustrating time. I'll roll my sleeves and start working on repairing this broken hawk...I mean hornet.. LOL. any other Ideas are always welcomed!

[ColtPilot]

I'm using everything based on the book! Can you post a picture of you battery placement?

https://photos.app.goo.gl/6vFYweCkL6UwJEpw7

my battery placement. Not all the way back as you can see. Plus I have the firey booty installed also.

[Mizer67]

https://photos.app.goo.gl/6vFYweCkL6UwJEpw7

my battery placement. Not all the way back as you can see. Plus I have the firey booty installed also.

How much does the afterburner light weigh? Adding that weight aft will change your required battery placement, of course.

[Hugh Wiedman]

Madness I have my RT 6250 (weight 790 g) as far back as possible (see photo below). Your HRB, a great battery so that's not the problem, weighs in around 825 g. Although my cockpit weighs 190 g, vs the stock cockpit at 45 g it makes a difference requiring it to be back more, but I do have the RC Geek twin burners in the back along with 1.5 ounces of lead in the elevator bay, so I agree that you could move the battery back some. Also, below are the locations of the elevators at 1-Flaps up, 2-Take-Off Flaps, 3- Landing Flaps, 4- full up elevator. This was at a CG of 92 mm, so a little less now since I'm at 98 mm.

[ColtPilot]

How much does the afterburner light weigh? Adding that weight aft will change your required battery placement, of course.

I have no idea. I just know I'm at 98mm CG. I use the S. W. A. G. Method with all my planes and it works out. Never had an issue.

[Hugh Wiedman]

How much does the afterburner light weigh? Adding that weight aft will change your required battery placement, of course.

The RC Geek twin burners weigh in at 26 g and the additional aluminum tape in the nozzles probably another 30-40 g, so not that big a deal. Also, I always balance my aircraft after everything is done, painting, urethaning, cockpits, ordinance, AB and a 250-450 mah battery for it, graphics, etc. so the battery placement is determined as the very final issue.

[Mizer67]

I have no idea. I just know I'm at 98mm CG. I use the S. W. A. G. Method with all my planes and it works out. Never had an issue.

My only reason for asking was that if we're talking battery position vs. CG location for Madness, you'll get a different locations that are necessary based on modifications that themselves add weight aft or forward of the CG.

[ColtPilot]

My only reason for asking was that if we're talking battery position vs. CG location for Madness, you'll get a different locations that are necessary based on modifications that themselves add weight aft or forward of the CG.

https://youtu.be/cYR4ppJR_kI

This one is on a different brand getting the CG right with battery placement. Gooniacs firey booty installed. 80mm.

[Hugh Wiedman]

My only reason for asking was that if we're talking battery position vs. CG location for Madness, you'll get a different locations that are necessary based on modifications that themselves add weight aft or forward of the CG.

Good point, you are exactly correct. Tim and I are both flying at about a 98 mm balance point, yet there is a huge difference in our battery placement. I think part may be the battery weight, as his is no doubt lighter than mine, but the seemingly 5" or greater distance mine is further back (plus my extra lead in the tail) is primarily due to my extra weight in the cockpit modification and the ton of paint and graphics I have over the stock Blue Angel of his, since we both have the relatively light weight AB's in.

[Mizer67]

Good point, you are exactly correct. Tim and I are both flying at about a 98 mm balance point, yet there is a huge difference in our battery placement. I think part may be the battery weight, as his is no doubt lighter than mine, but the seemingly 5" or greater distance mine is further back (plus my extra lead in the tail) is primarily due to my extra weight in the cockpit modification and the ton of paint and graphics I have over the stock Blue Angel of his, since we both have the relatively light weight AB's in.

I'm in approximately the same place for CG as you both and I have no AB or mods, other than paint.

It's (battery position) going to vary plane to plane, even without mods. Although they're somewhat consistent, they're not identical. I've had several Mirages for instance and some have been easier to get the CG more aft than others. I do think that most are flying somewhat aft of the recommended CG in the manual of 88mm, however, with a range of 95 - 105 mm being most common from what I've seen.

[Airguardian]

Wao! that's an eye opener! Yeap, mine is way front! I'll need to do that change for sure! Thanks a lot the picture!

Not that I necessarily recommend to do this (As my current setup is pretty extreme and requires a gyro to fly properly) but, when installed, my 870g battery disappears under the canopy lid, pushed all the way back. And that's in addition to using a Lightburner! ;)

Point is... yeah, way too nose heavy!

[Elbee]

Madness I have my RT 6250 (weight 790 g) as far back as possible (see photo below). Your HRB, a great battery so that's not the problem, weighs in around 825 g. Although my cockpit weighs 190 g, vs the stock cockpit at 45 g it makes a difference requiring it to be back more, but I do have the RC Geek twin burners in the back along with 1.5 ounces of lead in the elevator bay, so I agree that you could move the battery back some. Also, below are the locations of the elevators at 1-Flaps up, 2-Take-Off Flaps, 3- Landing Flaps, 4- full up elevator. This was at a CG of 92 mm, so a little less now since I'm at 98 mm.

Hugh, It Never Gets Old seeing pix of your Hornet. Truly a beauty. Thank you for all the great insight into your modded F-18C. Best, LB

[Mizer67]

Not that I necessarily recommend to do this (As my current setup is pretty extreme and requires a gyro to fly properly) but, when installed, my 870g battery disappears under the canopy lid, pushed all the way back. And that's in addition to using a Lightburner! ;)

Point is... yeah, way too nose heavy!

How do you secure the battery like that? Looks like you're past the last strap there.

I know mine, the last (only) strap I have effectively limits my ability to go back any further with the CG with the battery strap as I have it currently set up.

I'd need another slot further back with another strap to go any further. I don't see how you're securing the battery in the picture, velcro?

[Madness]

Madness I have my RT 6250 (weight 790 g) as far back as possible (see photo below). Your HRB, a great battery so that's not the problem, weighs in around 825 g. Although my cockpit weighs 190 g, vs the stock cockpit at 45 g it makes a difference requiring it to be back more, but I do have the RC Geek twin burners in the back along with 1.5 ounces of lead in the elevator bay, so I agree that you could move the battery back some. Also, below are the locations of the elevators at 1-Flaps up, 2-Take-Off Flaps, 3- Landing Flaps, 4- full up elevator. This was at a CG of 92 mm, so a little less now since I'm at 98 mm.

Thanks a lot for the reference pictures! By the way, you have an awesome looking jet! Truly a work of art. I see you are from Miami, I live in Pembroke Pines. I go to Markham Park for my flight times, where do you do your flying? Would love to see that plane in person and obviously pick your brain for tips on getting mine to work. Let me know!

[Mizer67]

Not that I necessarily recommend to do this (As my current setup is pretty extreme and requires a gyro to fly properly) but, when installed, my 870g battery disappears under the canopy lid, pushed all the way back. And that's in addition to using a Lightburner! ;)

Point is... yeah, way too nose heavy!

I think I see some kind of foam wedge now.

[Hugh Wiedman]

[QUOTE=Madness;n283001]

Thanks a lot for the reference pictures! By the way, you have an awesome looking jet! Truly a work of art. I see you are from Miami, I live in Pembroke Pines. I go to Markham Park for my flight times, where do you do your flying? Would love to see that plane in person and obviously pick your brain for tips on getting mine to work. Let me know![/QUOTE

I'm a member with both Markham Park Pilots Association and AMPS in Miami. Used to fly exclusively at the Park, but it got a little like flying at a Wild West Show, pilots doing just about anything they wanted. Last 2 years flying mostly at AMP's, grass field off of SW 156th Street and west of Chrome Avenue (out in the sticks), a beautiful facility, and I love flying off of grass which is cut down to only 1/2". Come to our Miami Jets Festival for the four days of December 10th-13th. Got very difficult to fly at the Park when corona hit and the lock down rules they imposed, so we even had to stop taking new members at AMPs for a while to keep the crazies from the Park away from AMPS. Our Treasurer with AMPs lives 2 minutes from the Park, but only flies now at AMPs. If you want to try our field out, send me a PM sometime and I can get you in for a tryout as long as I am there. One of my best "RC friends", and best EDF pilot out there, Brinka , still flies at the Park because AMPs is too far for him. I'm trying to put together an All Electric Fest at AMPs sometime next year (Motion, I still need your sponsorship because I just told HH to go pound sand) so I'll let you know when that is and will also include all the RC Clubs in South Florida. I even maidened my F-18 Canadian at the Park, take a look at the video below (next post I'll show the A-10 maiden at AMPS field so you can see what it looks like (we also have a huge covered area for setting up with to keep out of the sun):