Giant Foamie F-15 Scratch Build

[Otto Dieffenbach]

After building my large foamie Sea Dart (3 lbs 10 oz) and foamie Eindecker (11 lbs), I decided I wanted to add to my fleet of F-15s. I have a 9 lb F-15 that I built and first flew in 1973 and coverted to electric and flew earlier this year. In addition, I have a 1.2 oz outrunner micro and a 6 oz foamie that have been fun.

My project will be built from Home Depot materials with the primary material being 1/2" R-Tech foam insulation that comes in 4x8 sheets for $7. My target weight is 3 and 1/2 lbs with power system being my Scorpion 3026-980, 60 amp ESC and 4s5000 battery with an APC 10x7 prop. This will generate 5 lbs of static thrust and should make for great performance given my experience with the Sea Dart. Dimensions are 42" wingspan and 55" long. My design parameters included that it must fit in the car, takeoff from the ground (no toss launch), have great performance/handling (TBD) and be inexpensive to build.

This is my first build thread so as questions, if interested. I have taken a bunch of pictures that help explain the build and I will have more detail after first flight, which should be within a week.

[Otto Dieffenbach]

More photos...

[Slowjohn]

Interesting build.


Standing By,
SJ

[Otto Dieffenbach]

I've completed the build and will fly before painting. I'm waiting on a receiver that should arrive Monday. First flight Tuesday. Here are more photos. Total weight 3 lbs 12 oz.

[Larry3215]

Nice Otto!

What the plan for landing gear?

I started to make a comment about the elevons - possibly - not being enough for good roll control at low speeds, but the center portion is in the prop wash so that will help. Throttle off in a hi alpha attitude may leave you a bit lacking though.

Somewhere I have some shots of how to operate the elevons and ailevators from single servos - makes for extreme control in all axis

[Larry3215]

Here are some shots of how I did it.

Basically, when an elevon moves, the same side aileron goes in the same direction.

Both surfaces are driven from a single servo using a split push rod.

This gives you much better low speed roll control but it also enhances pitch control.

When you give UP elevator both ailerons go into reflex which allows the model to loop in a much smaller diameter circle and more importantly - maintain very stable hi alpha flight.

This allows for very scale looking take-offs and landings where the nose wheel comes up early before the mains take off. Same thing on landing.

You can easily take off or touch down with the nose hi and keep it there if you want while you roll out.

The mains need to be set very close to the cg for this to work well though.

Its pretty cool

oh - it also allows you to do a cool lomchavack and even tumble the model if the cg is back far enough at the same time.

[Otto Dieffenbach]

Thanx. I designed it to skid across the ground like the Polaris for takeoff. While on the Polaris, did you put the minus 2 degrees in your thrust line and stab? Looking forward to first flight Tuesday.

[Larry3215]

Originally Posted by Otto Dieffenbach

Thanx. I designed it to skid across the ground like the Polaris for takeoff. While on the Polaris, did you put the minus 2 degrees in your thrust line and stab? Looking forward to first flight Tuesday.

Yes I did.

Good luck on the maiden - get video!

[Otto Dieffenbach]

Ok, I accelerated my schedule and ripped a receiver out of one of my other aircraft to first fly this morning. Handles like the Parkjet version only better with thrust vectoring rudder. Vertical performance is excellent. Need to do some slight thrust angle ajustments for loop tracking.

Giant Foamie F-15 (Home Depot Special) flown by Otto Dieffenbach, 1st Fligh

[Larry3215]

Outstanding!

No lack of roll or pitch control at all. very cool!

Cant wait to see the color scheme you come up with

[CHELLIE]

Very nice build and flight keep up the great work, Chellie

[Otto Dieffenbach]

Sorry Larry, paint scheme not too exciting but functional.... no Thunderbird here.

[CHELLIE]

Very nice scratch builds Oh BTW, It will fly better if you Paint it Pink Just Kidding, Take care, Chellie

http://www.rcgroups.com/forums/showt...793637&page=16

[Otto Dieffenbach]

Cool. I've never had a pink plane but had some with pink in the scheme ala Circus Circus for TOC. Did have a friend with a hot pink Kwik Fly III back in the late 60s. Hot pink was all the rage...

[CHELLIE]

Originally Posted by Otto Dieffenbach

Cool. I've never had a pink plane but had some with pink in the scheme ala Circus Circus for TOC. Did have a friend with a hot pink Kwik Fly III back in the late 60s. Hot pink was all the rage...

Yes, Pink is easy to see in the air



here is my scratch built Katana below, I still have it

[CHELLIE]

My Friend Steve is doing the maiden flight on it, I am doing the video.

Scratch Built Katana Profile 9mm Foamie

[CHELLIE]

I Made a Blue one for Steve, He did not like Pink LOL , BTW if you would like to make one, the plans are in the thread, I used a Slow Stick fuse for the wing brace, i got it at BP Hobbies.
http://www.wattflyer.com/forums/show...katana+chellie

[Otto Dieffenbach]

Looks like a fun plane but I am really impressed with the video and your ability to keep the plane in frame. I need to get you to shoot some of my acro.

[HeliScRapYard]

This makes me want to get back on a project I abandoned a while back. I had planned to make a 200% RC powers F22 easybuild. Hopefully ill get some time to do that soon. Congrats on a good looking and flying plane.

[CHELLIE]

Originally Posted by Otto Dieffenbach

Looks like a fun plane but I am really impressed with the video and your ability to keep the plane in frame. I need to get you to shoot some of my acro.

Its easy to keep a plane in the frame but you need to make one of these mount the camera on the top bracket, aim the camera and the open sights at a object about 100ft away and adjust, set the zoom on the camera to about 1/4 or 1/3 and follow the plane with the open sights

http://www.wattflyer.com/forums/show...ighlight=rifle

[CHELLIE]

here is a video I shot of my friends fast moving heli, with the rifle camera mount.

Erans Trex 500

[eflight-ray]

Otto, I also enjoy large foamies, my last one, a sort of Mig 144, is EDP, Electric Ducted Prop(s). My use of a props was to keep the amps down from the usually very high ducted fans models. It worked quite successfully for what I wanted.

As for camera sighting, I tend to fly on my own and use one of the very small 'keychain' cameras mounted on the side of my sunglasses. Sighting can be a real problem, as I have found I often 'lead the plane' on fly-by's and end up film the sky in front of it. I had thought of mounting some sort of wire sight to the camera, but found a simple tiny 'spot' marked on one of the lenses has worked fairly well. It's not enough to get in the way, (it's out of focus that close up), but noticeable when following a plane.

Though I will use the excuse of only just having started using it, so I have an excuse for my poor video shots.

[Otto Dieffenbach]

I wish I was still travelling to Wales so we could share a pint. Impressive plane; what is the weight and static thrust? Are any videos on youtube? Great paint scheme. Thank you for sharing.

[Otto Dieffenbach]

Chellie, your solutions are impressive. Gold star for you. Now if I could only steady my Dad's hands.......

[Otto Dieffenbach]

3rd and 4th flights

Giant Painted Foamie F-15 3rd & 4th Flights by Otto Dieffenbach