Okay guys,
Right now with all of this talk of an Indoor IMAC deal I am in the mood to begin building one of these birds. I have some idea of where to start but really dont know the details on designing such a plane as I'm sure many others are. So if you are a "professional" Indoor IMAC airplane designer lets see some tips and tricks! Or if not just post some ideas of where to start for us!

A few questions as examples of mine:

-fuse length (long, short, ect.)
-bipelane or monoplane
-wingspan (long, short, ect)
-drag strips (when is too much? when is not enough? or are they needed?)
-drag holes (how many? what size? ect.)
-surface sizes (small, large ect.)
-horizontal fuse size (width , if needed)
-wings [leading & trailing edge sweep, rounded not rounded ect. (shape)]
-weight
-power
-batteries
-ESCs

I'm sure there are a few more questions that someone could ask; If so, please ask them!! Guys that will respond as an answer - we just want basic tips/ideas not a plan of a plane. Thanks FLYING GIANTS!! You guys make this kinda thing happen!

~Seth Arnold

Professional Indoor Imac Designer... I wish you could make a living at that........

In the past, I've kinda done stuff and been very 'ambiguous' in my answers... but with the indoor pattern/IMAC stuff, I'm trying to answer as straight as possible...... So I guess I'll throw my 1.5cents in (lost half a cent to depreciation)

Before you can answer any of the questions below, you have to decide - are you going to go get the best/lightest gear available, or are you going to try to build to something for gear you already have? Once you've decided that, then you can move forward.

IMO, the key thing you're shooting for in the basics of the design is the wingloading. At this size (for indoor pattern/IMAC), I think a wingloading of 2.5-3ozs sq/ft is a good starting point for a monoplane and approx 80% of that or less for a bipe of equiv size. I've seen two schools of thought in the European designs - Light monoplanes with an all up weight of 120~ grams or somewhat larger biplanes in the 170~180 gram range.

I guess I'll answer the rest below after your questions....



-fuse length (long, short, ect.)
I'd start at around 30" or so..... but thats only a beginning point.
-bipelane or monoplane
If you've never designed anything before, stick with a mono. Bipes are wonderful, but are more complex to build and aerodynamically
-wingspan (long, short, ect)
I'd start at around 30"~34" depending on the wingloading you are trying to achieve with what gear....
-drag strips (when is too much? when is not enough? or are they needed?)
Get a good flying airplane first. Then experiment with aerodynamic aids (if they are even allowed)
-drag holes (how many? what size? ect.)
See drag strip answer above
-surface sizes (small, large ect.)
You'll get a lot of varying answers on this one, but I go to the school of larger tail surfaces. I get more issues with small horiz/ele's than I do with large horiz/ele's. Same goes for vert/rud's
-horizontal fuse size (width , if needed)
I'd highly suggest using a shocky style fuse. Wider gives more strength....
-wings [leading & trailing edge sweep, rounded not rounded ect. (shape)]
Since you asked about an indoor IMAC plane, this will be decided by the full scale airplane you decide to model
-weight
Answered above.... (my personal indoor IMAC YAK is 110 grams RTF)
-power
If you plan to get the best stuff, the Axi 2203 is a good bet though I've not yet run one, the Cyclon Nano runs well, as does the Park 250. The lightest is the Mighty Midget from BSDMicroRC (requires light building, but its the lightest by a good margin)
-batteries
I'm having good luck with the 2s 360 and the 2s 460mah packs from 2DogRC.com.
-ESCs
The Castle Creations Thunderbird 9 ESC is cheap and does the job with almost no weight penalty (an ultralight version of this is available from BSDMicroRC and its still inexpensive)

I hope all this helps you. Again, this is all just my opinion, but I do know it works.

Good luck!!!!

Okay thanks for the info above, but what about designing a plane that isnt exactly modeled after a full scale? I understand that IMAC is scale but what about changing a few things?

Thanks again!

but what about designing a plane that isnt exactly modeled after a full scale

All of the info above stays the same. Of course with the exception of the wing planform question. To answer that question, I'd suggest doing some searching on this site regarding wing planforms. There were some great discussions about Edge planforms vs Extra style, etc. From a design standpoint, its hard to go wrong with an Extra style planform.

It never hurts to go look at what others have or are doing. Learn as much as you can by looking at their designs and apply details you've learned to your own designs. Here's a great photo set of a recent Euro event..... (BTW, all the winning planes in Carvin this year were monoplanes....)

http://www.flandis.ic.cz/fotky/adamov/index.htm

Also, what about the pattern style of flying that you can do anything for? (or almost anything) is it the same as well?

Thanks!!!!

Also, what my someone do to strengthen the plane - carbon fiber on leading/trailing edge of wing? Or kevlar from the vertical fuse to the wing? Both? Any other ideas?

Thanks again!!

Also, what about the pattern style of flying that you can do anything for? (or almost anything) is it the same as well?

Can't say that I understand the question? What are you trying to ask?

Also, what may someone do to strengthen the plane - carbon fiber on leading/trailing edge of wing? Or kevlar from the vertical fuse to the wing? Both? Any other ideas?

Good question!

First off, right now, I'm trying to build so light that I need very little carbon reinforcing. Normally, I use a fair bit. However with these airplanes, I'm trying to get to a point that I don't need to use as much carbon. The lighter the airplane is, the smaller amount of support structure you'll need.

In order to accomplish that, I don't think you need leading edge carbon. My Sentinel had a carbon spar on the CG of the wing, but I deleted that for its IMAC YAK sibling and it did not suffer. I do use carbon 'flying wires' under the wing to stiffen it substantially.

I also use carbon trusswork on the underside of the fuse to keep the tail from twisting(eliminating the dreaded "shocky tail twist"). Finally, I use some light carbon to stiffen the tail surfaces.

BTW, here's a pic of my Indoor pattern airplane and of my Indoor IMAC airplane. If you look closely, you'll see they are very similar in construction and makeup.

(Yeah, I know I've put pics of these things up before....)

Videos Jeremy!

Videos Jeremy!

Here's a good F3P flight from a couple of months ago. Among other things, I flew the tophat incorrectly and my landing sequence was not quite right..... but I think it shows what this aspect of the sport can be like. : )

http://www.theprofilebrotherhood.com...my%20Chinn.wmv

We are having indoor night tonite, so I'll get some vids of my indoor IMAC plane in action. I only have the FAI sequence memorized, so I'll use that for my aresti.... : )

http://www.hobby-lobby.com/yak54.htm

Great plane and motor combination!

Videos Jeremy!

Here ya go Wayne-o-san!

https://www.flyinggiants.com/gallery/showphoto.php?photo=18177

(yes, I know I posted this in my build thread as well....sorry for the double posting, just seemed relevant to both threads)

seth, get a design going and i'll draw it into cad for you and we can cut it out with my cnc router. i would love to see what you come up with. should be a fun project. later, toby....
www.silhavyaerosports.net

Originally Posted by Matchless

BTW, here's a pic of my Indoor pattern airplane and of my Indoor IMAC airplane. If you look closely, you'll see they are very similar in construction and makeup.

(Yeah, I know I've put pics of these things up before....)

whats the wingspan and fuse length?