Greg Covey

Bill,

Yes, that combination should work nicely!

Regards.

bandit13

My Feedback: (1)

Greg,
Thanks. I know you stated that you will not be using retracts, but can you use them on the 70mm. Also, in your experience have you come across any EDF motor/fan setups that sound somewhat like turbines I have heard that the jet screamers do. Any thoughts? If I want to use servos for rudders, ailerons, elevators, and retracts how many servos do I need.

Bill

Greg Covey

Bill,

Yes, you can use the micro CNC retract set on the F-18. It is sold most places that sell the jet.

The only EDF jets I have seen that come close to a turbine noise are the high-end ones using a BVM Viofan, E-Turbax, or Byron conversion with a Scorpion motor.

As for servos for all those functions, you'll need plenty of them. 2 rudders, 2 ailerons, 2 elevators, 3 retracts (4 if steerable).

Now you can start to see why I made the design choices for my twin 70mm F-18.

Good luck!

bandit13

My Feedback: (1)

Greg,
Thanks for the information. I want fly the jet with everything, reason is so I can keep sharp when I fly a turbine jet with 12 servos. The field I use is to small for turbines and I can't always get away on the weekends to the bigger field. Your thread has been a excellent insight into the HET jets, keep it going.

Bill

JR16

I got my f-18 last week and i was looking at it i dont think there is any real way to get the main retracts in because the intake tubes are in the way. so i decited to build mine with the fixed gear because i like touch and go's lol

bandit13

My Feedback: (1)

Hey Greg,
If I had a Blue Angel scheme HET F-18 could I sand off the blue and yellow and primer it and then paint it grey.

Greg Covey

Hi,

Re-painting is not one of my fortes. I would try painting the bottom hatch first without sanding and see how you like it. It may save you the work of sanding and priming the existing finish. Otherwise, your technique should work fine.

The wings and elevator sections will need to be recovered, not painted, with whatever color you choose.

Although it snowed here today, Spring is just around the corner!

Good luck!

bandit13

My Feedback: (1)

Greg, I know the feeling of weather, spring is when we get the most snow. I have lived here 16 years and this year has been a very milded winter SO FAR. As far as the JET I will just buy a Gray version.

ingas

Hello.
           I purchased a mig-29 HET twin. Iam abit confused to how to wire -up the two - HET 2W-20 motor with the-Tsunami TS 72 ESC-. I have two fullymax 25c-3700mah 14.8 4s batteries. do i use a battery for both motors or a battery for each of the motors. this is my first electric plane i'am building. and what is the BEC used for. any help will be appriciated. thank you

Greg Covey

Hi,

I would use one battery pack for each ESC and then connect the control lines from each ESC to a Y-harness going to the throttle channel on your receiver. If your TS 72 ESC has a built in BEC, then you must disable one of them by disconnecting the center red wire going to the Y-harness. In other words, you want to only use one of the ESC's BECs to power the receiver an servos.

If the ESC does not have a BEC, then use either a Rx. battery or an external BEC like the Castle Creations CC BEC.

Good luck!

-

For those wondering if I have flown my F-18 yet...my first two attempts to bungee launch it, and one hand-launch, were not successful but resulted in only minor damage. We now feel that we need 3x the plane weight as the pull force to make the plane start flying about half way through the bungee launch length. This formula has worked on other planes and we finally measured my existing pull at only 16lbs or about 2x the plane weight.

Strega1

My Feedback: (7)

Hello Greg,

Where are all the good looking pictures of that great lookin F/A 18 you said you were going to post of the first flight. I have been waiting for those photos. Talk to you soon.

Ben Cubillos

Greg Covey

I decided to give up on my bungee launch approach and install the landing gear. I used an E-flite S75 servo for the nose steering with a short and stiff control linkage. Although my first opportunity to test fly it off pavement is not until August 1st in Hamberg, NY, I will likely get an earlier chance to see if it will take off a short grass surface. The HET F-18 has plenty of power so I'll see what happens and report back.

Greg Covey

I had a chance to try the HET F-18 from grass using the stock wheels. We really thought it was going to take-off but it just missed having enough speed using the stock wheels. I have since swapped the stock wheels for some Dubro (225TL) 2-1/4" Treaded Lightweight Wheels which are slightly bigger and much harder than the soft foam ones supplied with the model. I will test the F-18 next off pavement on August 1st, and if successful, I will try it off grass again with the new wheels.

[link=http://www.gregcovey.com/reviews/HETF18a.wmv]HET F-18 Stock Wheels Grass Take-off Attempts Video[/link] (4.5meg)

Strega1

My Feedback: (7)

Hi, Greg

I saw your take off attempts on grass. Looks like you could not muster enough speed to take off. Were you going to take off ? I wish you a lot of luck on your next attempt.
I'm finally getting back to finish my F 18 jet. My target date is for the next 3 weeks, give or take. I will take a vidio when I fly my F 18 and I will post it.
I hope yours has flown already. Talk to you soon.

Ben Cubillos

Strega1

My Feedback: (7)

Hi, Greg

I saw where you placed the electronic speed contols, up front where the front landing gear is. You said that you were going to make provisions to cool the ESC's. Did it work out for you ? The problem that I have is if I mount the ESC's behind the motor/fan units, will the esc's reduce the effectiveness of the fan units ? What if I just mount them outside of the fan tubes. Will they get hot and quit on me ? Let me know what you think and also if you can offer some suggestions.I hope to hear from you soon.

Ben Cubillos

Greg Covey

Hi Ben,

Although I replaced the soft stock foam wheels with larger Dubro rubber wheels, my enthusiasm to get the F-18 in the air made me try it again off of grass instead of waiting for my first opportunity off pavement. The F-18 got light and ready to fly off grass but veered to the left and a cross wind rolled it over into a cartwheel. Without a rudder, we lost steering authority once the nose wheel got light. The harder Dubro wheels did help to take-off from grass.

The damage wasn't bad and I fixed it all except for a stripped elevator servo. Unfortunately, other projects have taken priority and I will now leave the HET F-18 repair to a winter project.

The ESCs should have some air flow over them so either keep them inside the exhaust tubes or move them up front like I did and add some air entry holes in the nose, and some air exit holes under the fuselage. Otherwise, keep the initial flights short (3 minutes) until you test the whole system out.

Good luck!

Strega1

My Feedback: (7)

Hi, Greg

Thanks for the information. At least I have an Idea on how to do this.

Ben

bandit13

My Feedback: (1)

Greg,
Have you every put on a strake(fence) on the lex similiar to the real F-18C. I wanted to do this but don't know where to begin. Since I am using decals that use the strake for an acroynm of the squadron that this would add some realism to the jets.

Bill

rctech2k7

My Feedback: (1)

Hi! Greg,
I have the same jet except that the color is gray. I found the same problems with the jet and did some modification already. I started with this jet using 5Ah 5-cell 25C lipo battery and I have good thrust which is around 70% of its weight using the original factory recommended setup. I like this jet and it flies great even on low and high speed except on some few problems. The landing gear is flexible and it caused a lot of bouncing for most landing. Another thing is landing on high alpha is very difficult because of a very small elevator control. I suggest if the company can produce it with the full horizontal stabilizer and pre-built retractable landing gear provision would be better. Now, my jet has modified stabilizer and complete retractable landing gear using 1/8” piano wire, so I can land smoother with high angle of attack. The only problem I got was the weight of the plane so I ended up upgrading the battery from 5S to 6S and make the rudders operational.

Here’s the full detail of the plane:

Aircraft Name: HET F/A-18 Twin EDF Jet
Description: Scale F/A-18 Twin EDF Radio Controlled Model Jet
Airframe Maker: High-End Technology
Built: October 2008 Maiden Flight: Oct 22, 2008 Status: Active, 233rd landings as of Oct 6, 2009
Length: 56" Wingspan: 39.3" Flying Weight: 8.7-lbs (3.95-kg)
Power System: 2 x 70mmØ EDF w/ Typhoon 2W-25 & HET 75A ESC on FlightPower EON28 22.2V 28C 6S LiPo 5100mAh total capacity (upgraded Apr 11, 2009)
Thrust: 6.4-lb @ 3.08-kW 50,000-rpm. Wing loading: 3.85-lb/ft²
Setup mode for flight control surfaces: Ailvators and flaperons
Updates: Retractable landing gear, full horizontal stabilizer and operational rudders

Flight Video: [link=http://www.youtube.com/user/rctech2k7#g/u]My YouTube Model Aviation Video[/link]

Aircraft photos:

Original high wing setup: (poor crosswind capability)





Corrected wing (after I cut and glued it back, this one can handle hard crosswind on takeoff and landings)





With modified horizontal stabilizer



Good luck and I hope you can bring it back in the air...!
John

Greg Covey

Bill,

I have not added a strake before. Perhaps if you post your question in the Turbine Jets forum you will get an answer. There are plenty of members with great building experience in that forum.

John,

Thanks for posting your grey F-18 setup. I like the look and will check out the video from home as YouTube is blocked here at work.

I am certain my F-18 would have flown off pavement but the grass take-offs require just a bit more power. I still plan to fix my elevator servo this winter but just didn't have the time during the flying season with so many other planes to focus on. I am already planning my winter building projects to keep me occupied in the long cold months up North.

Regards.

JR16

rctech2k7,
do you have any other photos of your modifications? it looks like you added anhidral(sp) to the wing? how did you accomplish this? i was wondering if you checked the incidence of the wing because my left wing is visibly lower infront compared to the right. do you have any photos of your retract setup? i fly from very short grass that is short enough to get a stock f18 foamy with a single 64mm fan off the ground. so, im not too worried about that but, am wondering if the retracts would hold up to the grass? what retracts are you using? with your stablizer mod did you make a whole new stabs or did you just fit the two piece ones together? lol im sorry for all the questions but, im kinda nervous with this plane as its my first real ducted fan jet, i have had a few foamy ones most notably the f-18 from bananna hobby which i upgraded the fan, motor and, lipo so its pretty quick. I have been flying mostly gas planes with the ocassional park zone model so when it comes time to setup the electirics im gunna be picking quite a few brains lol.

thanks
John

JR16

opps just ignore this post, sorry

rctech2k7

My Feedback: (1)

Hi! John
I just took some photos of my modifications and here’s what I got. The plane doesn’t look good but for reference hope it will help. I couldn’t get a chance to repaint the plane since from the last time she looses the nose gear screw and went to the grass on takeoff attempt. It leaves a visible crack on the nose.
I’m using Robart 520W1 Tri Gear 90 Deg Rail Mount retract. I made a new pair of stabilizer from piece of plywood but I suggest if you haven’t install it and planning to make full stab better to glue the original one together using epoxy as full stabilizer because plywood is too heavy. Also, check your throw and put stopper on servo. Fly her first with the original landing gear setup since it’s easier to install. How’s the setup of your jet right now? Let me know if you have any question.
Regards,
John