questions about first scratch built F3P plane - RC Groups
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Nov 01, 2015, 05:40 PM
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Question

questions about first scratch built F3P plane


First off let me say this. Im a F3A guy. I fly Almost 2m planes so F3P is some what new to me.

Anyways with the flying season ending soon(or at least in the eastern coast of the US) i've been thinking about building a little F3P plane to fly around my front yard. I really like the Snoopylution.

But first I have a couple of questions. I've have experience building planes with foam boards but what foam should I use. Before you say depron I have a tight budget(under$100) and Depron is rather pricey per sheet.
I'm not planing to build a super light 80g(i know they get lighter) plane so could I use dollar tree foam board and remover the paper or should I use something like Midwest products Cellfoam.

As for the electronics I would think that something like this would work for the motor, this for the ESC, and these for the servos.

So what do the more experienced indoor pattern pilots think.

Thanks
-Sam
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Nov 01, 2015, 07:16 PM
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Quote:
Originally Posted by Sierra_bravo
But first I have a couple of questions. I've have experience building planes with foam boards but what foam should I use. Before you say depron I have a tight budget(under$100) and Depron is rather pricey per sheet.
I'm not planing to build a super light 80g(i know they get lighter) plane so could I use dollar tree foam board and remover the paper or should I use something like Midwest products Cellfoam.
Well, Depron is clearly the best choice but the $tree foam board can work. It is flimsier in every way and you will probably need more carbon bracing or double thickness foam in places.


Quote:
Originally Posted by Sierra_bravo
As for the electronics I would think that something like this would work for the motor, this for the ESC, and these for the servos.

So what do the more experienced indoor pattern pilots think.

Thanks
-Sam
First off, have a look at this thread:

https://www.rcgroups.com/forums/showthread.php?t=550372

It is stickied at the top of this forum and has many F3P plans linked in it. I built an Index 3 from that list, it is just waiting on the indoor season to start here.

Second, you need more motor, less ESC and bigger servos. More like these:

http://www.hobbyking.com/hobbyking/s...Outrunner.html

http://www.hobbyking.com/hobbyking/s...ontroller.html

http://www.hobbyking.com/hobbyking/s...cro_Servo.html

That 2204 motor turns 8" props with authority and weighs 21g, perfect as a budget choice for F3P. The ESC I link weighs 6g instead of the 19g of yours. If you think you need more current, go with the 10A version of the Plush ESC. If you want better servos for a slight weight penalty have a look at these:

http://www.hobbyking.com/hobbyking/s...5kg_07sec.html

They cost a bit more but are digital and have better centering and precision than the HXT500.

My $0.02 for a budget F3P model.

Mark
Nov 01, 2015, 07:53 PM
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Thanks for the recommendations on the parts. I read the thead that you posted and I decided that i like the F3X more. I was thinking about strategically adding bamboo skewers to the foam to give it some strength (and to save $) and doubling the foam on the fuse. Also how effective are air brakes to add drag and slow down the plane. Do they have any disadvantaged besides having to apply more throttle on up lines therefore reducing flight times

-Sam
Nov 01, 2015, 08:22 PM
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Quote:
Originally Posted by Sierra_bravo
Thanks for the recommendations on the parts. I read the thead that you posted and I decided that i like the F3X more. I was thinking about strategically adding bamboo skewers to the foam to give it some strength (and to save $) and doubling the foam on the fuse. Also how effective are air brakes to add drag and slow down the plane. Do they have any disadvantaged besides having to apply more throttle on up lines therefore reducing flight times

-Sam
If you get the air brakes set right they only cost you more current, nothing else. The competition guys care because it affects how big of a battery they have to carry but for you and me that isn't as big an issue. Make them removable whatever you do, flying outside as you mention will likely not need any brakes at all. I fly indoors in a basketball gym and doubt I will be running brakes on the Index, but I am not trying for F3P perfection, just flying to improve and amuse myself through our long winters.

My Index hasn't flown yet but I have a Nutball with the 2204 motor that flies for 8+ minutes on a 360maH Rhino 2S lipo with no problems. Assuming the Index is similar, most flying is at less than 1/2 throttle. Since you fly 2m F3A you should be familiar with throttle control and having excess power when you need it.


Mark
Nov 01, 2015, 08:41 PM
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With the larger 2m pattern planes I know you want more drag in the tail to make loops smoother and to make sure the tail is always behind the aircraft. Not to sure the same applies with less then one meter pattern planes though.

Im probably in the same boat as you when it comes to f3p. Not going to compete but I do want something aerobatic to fly during the winter. Which is why I dont want the lightest plane with a 10g motor and 3g servos. I just want something fun to fly.

Well I got the plans printed out and I'm cutting and taping them together right now. I'll also get the foam tomorrow but not sure when I'll get the parts. I recently blew a large portion of my rc budget on a new hitec aurora 9.

I wonder if I could use one of the old CD-ROM drive motors
-Sam
Nov 01, 2015, 10:28 PM
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Well it looks like I'm going to have to use some closed cell foam because the size of $tree foam board is 30"x20" and the fuse of the F3X is slightly more then 30".

If anything the closed cell foam is lighter and stronger then the $tree foam board. Also it more durable in a crash and can be fixed/built using normal Ca. The downside is that its more expensive then $tree foam board.
-sam
Nov 01, 2015, 10:32 PM
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Quote:
Originally Posted by Sierra_bravo
Well it looks like I'm going to have to use some closed cell foam because the size of $tree foam board is 30"x20" and the fuse of the F3X is slightly more then 30".
You can easily splice pieces of foam together to make whatever dimensions you need. A properly done glue joint will be as strong as the foam and adds minimal weight overall.


Mark
Nov 02, 2015, 09:58 AM
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True. I found a scrap piece if dollar tree foam and some midwest products cell foam and I compared the two.

The $tree foam was lighter but it was way to flimsy and bendable. Im sure you could fix the problem with bamboo rods but it would add a fair bit of weight. As for the closed cell foam. It's a lot more sturdy. It doesn't bend as much but it can snap easily. As for building with the different types of foam. The $tree foam needs to be built with hot glue, which is heavy, while the closed cell foam can be built with CA, which is a lot lighter then hot glue, and cheaper.

So I decided to go withe the closed cell foam as it'll work better the the $tree foam for this plane
-Sam
Nov 02, 2015, 12:35 PM
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Trisquire's Avatar
You can't use CA on $tree foam?
Nov 02, 2015, 12:45 PM
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nope it eats through the foam. Well at least normal CA does I never tried foam safe CA.
Nov 02, 2015, 01:36 PM
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Trisquire's Avatar
Normal CA will eat through any foam. You have to use foam safe CA.
Nov 04, 2015, 01:34 PM
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Well it looks like im going to have to use $tree foam because after going to three hobbylobbys, two walmarts, and one michale's I found out that the either no one uses cell foam or that cell foam is hard to sell. Any ways I'll pick up some foam board, x-acto blades, and hot glue later. Also I'm thinking making the a wings 6mm thick

-Sam
Last edited by Sierra_bravo; Nov 04, 2015 at 01:40 PM.
Nov 06, 2015, 04:56 PM
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Well I picked up some $tree foam board and each sheet weighs 114 grams. not sure if that alot lot or not though.

Anyways I'll get the plane cut out today and post some pics later. If I have time

-Sam

Oh and I would of bought the parts but I had to buy a new prop adapter for my large pattern plane. The one prop adapter actually cost as much as all of the parts for the F3X. So I still wont have all the stuff for the F3X
Nov 06, 2015, 09:38 PM
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So the weight in grams of the fuse without the wings or the servos, battery, and motor/prop/ESC is 72g or 2.5oz. Also I didn't remove the paper since it gives it so much strength.

So is that heavy for a plane of this size?
Nov 07, 2015, 11:56 AM
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I finished the plane and the weight without the servos, battery, and motor/prop/ESC is 130 grams or 4.5oz. Which is alot for an indoor f3p plane but since im going to fly the plane outdoors the weight helps if there is wind. Im guessing that the AUW is going to be between 230 and 240 grams. So around 9/10oz which isnt bad at all for a small outdoor plane.

-Sam

Note that the wheels dont spin. Since im going to hand launch the plane the landing gear is only for landing.
Last edited by Sierra_bravo; Nov 07, 2015 at 12:40 PM.


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