Got a new idea and GWS mini mustang. - RC Groups
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Sep 20, 2006, 02:26 PM
crashin with a smile
sirdirk007's Avatar
Discussion

Got a new idea and GWS mini mustang.


I just got a mini mustang. http://epyaya.com/product_info.php?c...fedf94b72534d3 I was thinking of converting it to an rc electric but then thought hmm, if I leave out the motor I could make it a 22" sloper. I know it will not be a fast bird. That is not my intent. My intent is to have a little bird for the super light days.

Here are some ideas I an thinking of,
1. add 1/16 or 1/32 balsa to bottom of wing to get rid of the camber and make wing symetrical.
2. Use a small 1/2"X1/4" bass for spar and cut the dihedral into it so its solid.

3. No rudder to help keep it light.
4. Elevator servo inside body
5.Single aileron servo with usual push pull rods inside the wings so the aren't seen. Or should I use rudder and no aileron?
6. No motor.

I am using 4.3g servos and a gws 4ch rx.
I know there are those who say can't be done and those who will say go for it so I am. I am pondering a couple of questions how ever.

I know this is a silly question but enlighten me please. How do I calculate wing load? I think I get it but for some reason I am having a brain fart.

Also, If I were to leave the prop on as a free spinner would this cause too much drag? I really like to see that on these old war birds and they just look so naked with out them on the slopes. I do know why they are leaving them off but again I am not going for speed.
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Sep 20, 2006, 05:05 PM
Long to be flyin'
Antonsoarer's Avatar
Quote:
Originally Posted by sirdirk007
I just got a mini mustang.
I know this is a silly question but enlighten me please. How do I calculate wing load?

Also, If I were to leave the prop on as a free spinner would this cause too much drag?

Wing loading = Span" x average chord" / 144" = #Sq' then.. Weight in oz /#sq'

The prop will slow it down and increase the sink rate, suc and see but best leave it off or make and fit one with a very fine ptich to reduce drag.
Sep 20, 2006, 05:16 PM
crashin with a smile
sirdirk007's Avatar
thanks anto,

Now to do some math.

So 5oz / 111.5 sq"= .049 wing load. This seems very good. Considering the plane will weigh 4.5 or so oz rtf. Wow This may have to be a really light day or bye bye little plane.
Sep 20, 2006, 05:24 PM
Registered User
codezilla's Avatar
Quote:
Originally Posted by sirdirk007
thanks anto,

Now to do some math.

So 5oz / 111.5 sq"= .049 wing load. This seems very good. Considering the plane will weigh 4.5 or so oz rtf. Wow This may have to be a really light day or bye bye little plane.
You need to multiply .049 by 144 to get oz/sq ft. so the wing loading is 7.056 oz/sq ft.

Adrian
Sep 20, 2006, 05:34 PM
Dave Massongill
masson74's Avatar
7 oz /ft is good but trust us leave off the prop. If you want a propfor when its sitting still on the ground put on a static one that you can take off for slope flight.

dave
Sep 20, 2006, 05:36 PM
crashin with a smile
sirdirk007's Avatar
Ooopss, I forgot that part. 7oz would be better as I fear the plane may be too light anyway. Would you recommend painting the balsa I will add or just placing an ultra light covering or ??

Great idea masson,

I can make a static post that I can build into the nose ballast and that would be permanent and the prop would be removable. Well I will start on it tonight a bit, I will do my best to post pics but I have some plans as well tonight so may not get much done.
Sep 20, 2006, 05:43 PM
Long to be flyin'
Antonsoarer's Avatar
Quote:
Originally Posted by sirdirk007
thanks anto,

Now to do some math.

So 5oz / 111.5 sq"= .049 wing load. This seems very good. Considering the plane will weigh 4.5 or so oz rtf. Wow This may have to be a really light day or bye bye little plane.
Close but you need to divide the 111.5 by 144 to get square feet so that will be 0.77 square feet. Then divide 4.5oz by 0.77sq' to get 5.81 oz per square foot.

That's plenty light, should stay up in a very light breeze but may not handle anything above about 12mph too well.
Last edited by Antonsoarer; Sep 20, 2006 at 06:27 PM. Reason: typo
Sep 21, 2006, 11:38 AM
crashin with a smile
sirdirk007's Avatar
Quote:
Originally Posted by Antonsoarer
Close but you need to divide the 111.5 by 144 to get square feet so that will be 0.77 square feet. Then divide 4.5oz by 0.77sq' to get 5.81 oz per square foot.

That's plenty light, should stay up in a very light breeze but may not handle anything above about 12mph too well.

I am guestimating AUW to be around 5-6oz I am trying to factor in the balsa and spar. Also the balast for the nose. So things may change slightly as well. Thanks for the correction though and I really appreciate the help.

I will post pics soon
Last edited by sirdirk007; Sep 22, 2006 at 03:25 PM.
Oct 13, 2006, 10:39 AM
crashin with a smile
sirdirk007's Avatar
Here are some pics. Its almost complete. I just need to add rx and aileron control horns and push rods. I also need to paint wing bottom and find or make super small batt pack.

Weight currently is 4.8oz
Oct 13, 2006, 12:44 PM
If it ain't broke...break it!
Hangtight's Avatar
Small light battery packs. Use a smallish 2S LiPo and a voltage regulator like this one.

http://www.ekmpowershop2.com/ekmps/s...&productid=486

About half the weight of a NiCad.

Good luck!
Oct 13, 2006, 01:27 PM
crashin with a smile
sirdirk007's Avatar
Most rx will operate on 7v. I was thinking of just using a 4cell AAA rechargeable pack. I use one in my dlg and it seems to be light enough. I also need roughly 1oz or so in the nose anyway to get cg
Oct 13, 2006, 04:31 PM
If it ain't broke...break it!
Hangtight's Avatar
Cool. Go with what you got, and if you need the weight all the better!
Oct 14, 2006, 12:04 PM
crashin with a smile
sirdirk007's Avatar
Who makes batt packs the for a great price. I would need a square pack configuration 11 Set up like this in tripple A I can make my own but
11 if the price is right its not worth my effort.
Oct 14, 2006, 01:31 PM
Life is Good!
Tank52's Avatar
Check out Cheapbatterypacks.com

I've always received great service and fast shipping from them. You can design your own packs. I purchased almost all of my Nimh packs from them.

Tank


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