New EPP Foamie - the Firefly Delta...

[akent]

I have been on the lookout for more of these instant gratification EPP foamies!
Well, ones that can be built in a few hours max that also fly great! I want EPP as planes built from this are like super balls. They generally just bounce off of the ground!

After looking, I found this plane called the Firefly. It is a mid engine Delta design with a KF airfoil.
I thought that sounded interesting, so I made one.

Here are the plans for a single sheet:

Attachments:

[akent]

And here are the tiled letter sized plans:

Attachments:

[akent]

Here is what I built mine with:

1.9# EPP foam from Grayson Hobby (www.graysonhobby.com).

Motor: Turnigy 2730-1500kv
Prop: GWS 8x4
ESC: Turnigy Plush 18 amp (mid timing)
Servos: HXT-900's (three)

I like this delta design as it has a rudder!

The hinges are made with Welder glue!! I posted in another thread about how to do these.

[akent]

The website for the design said that it needs NO CARBON reinforcements!!!!

HOGWASH! Well, unless you want a floppy thing in the air!

I built this one from 1.9# EPP and it was FLOPPY!! I can't imagine building one from 1.3# EPP.

I added only three pieces of CF at this point. One on the bottom as shown the next picture (3mm square) and two on the top that go in a 'V' from the rudder to the outer edges of the wing (3mm square), that are shown in the above pictures.
Now, I trust the thing to be flyable. I don't do FLOPPY!



Here are more pictures of the bottom:

[akent]

AUW with a 1000ma 3s battery: 12 ounces.

Thrust aiming down on a scale: 22 ounces.

So, this should have some good performance.

I have not flown this yet. I hope to tomorrow, if the weather is good...
Kent

[19000rpm]

Nice looking little plane. I really think your going to like the rudder for 3D.

Look forward to the video.

Might try one of those when I get some of these other pojects finished.

[Gabe]

Cool little devil! For an hour's work that's darn cool man.

[akent]

Thanks!
I still haven't flown it. Chores to do!

I forgot to include the link over at RCGroups for this bird...
www.rcgroups.com/forums/showthread.php?t=943610

[Solitaire]

I see "KF airfoil" mentioned numerous times on various threads, but haven't found a description. What is this exactly?

[19000rpm]

May 2, 2010 13:45:07 GMT -6 Solitaire said:

I see "KF airfoil" mentioned numerous times on various threads, but haven't found a description. What is this exactly?

It's a stepped airfoil. The KF stands for the designer Kline Fogle something or other. They've used the design in boat hulls too. It provides enhanced lift with less drag among other things I don't remember. ;D

[akent]

Yep, the KF foil is exactly like 19k says.

And I can tell you that this plane flies like crap. I am disassembling it as we speak.

No amount of CG movement keeps it from porpoising like crazy. I can't imagine flying this without CF, but they do it on the RCGroups forum. I even added more at the field.

It is Ok for a VERY slow flyer. You just can't go over about 20mph before it starts porpoising. By that I mean a very slight amount of down elevon causes a nose dive, and a slight amount of up to counter that causes it to shoot for the moon. BOGUS!

I don't like it and will toss it in the trash soon.
Kent

[19000rpm]

Too bad it didn't work out. Looked like a neat idea though. Back to culling the plans posts I take it? Let us know what you come up with.

[akent]

Yep, it's a lot of fun looking at all the plans and trying something new!

I have a couple in mind!

One is the Cutlass (a better looking delta), and then the EPP Edge 540 T. The Edge was designed by Leadfeather, the same fellow who designed the Yak 55. I know it will fly well, but that's also not quite what I'm after...
What am I after? Heck, I don't know! Something that is awesome! The F-22 is awesome! It also loves the wind, but it's not very maneuverable. The Yak is good for 3d stuff, but sucks in the wind.

I want a 100mph capable 3d machine that costs 10 bucks in foam to build. How about that?
Kent

[19000rpm]

Does Area 51 have a website with plans on it

I am going to make a wild guess as to what makes up that plane Kent. I think it's got to be a modified delta. Maybe an F35? It's going to need an airfoil. It's going to need to be glassed if you use EPP. It's going to need a 600W motor. You're going to need a bigger budget. ;D

[akent]