Slow Combat One Design - RC Groups
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Jan 08, 2011, 09:14 PM
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Slow Combat One Design

I am proposing a local Slow Combat class with tightly controlled parameters. A few years ago, myself and several friends had Soarstars and would chase each other with them. Since they were all the same size and shape it was very easy to judge distance and you could track each other. The rocket ships that we have recently used for combat are not as much fun.

The Slow Combat One Design wing is built using the full width of the 48” fan fold or protection board with a KFm2 airfoil made using the factory fold as the leading edge. The only motor allowed is the TowerPro 2408-21 powered by a 2 cell battery. The motor is usually available with an ESC for $20 to $25. I used Tower Pro MG90 servos which cost $10 each.

The idea for using the factory fold for the leading edge came from the “Blue Funder” thread

I decided to put the step at 40 percent after watching the videos of the “Scrathbuilt Swifter CHEAP Sloper Plank from FFF”

The plane is performing as I had hoped. You must keep in mind the original intent and resist the urge to make it better, faster, more maneuverable, etc.

Rules and a rough sketch are attached. NOTE: The drawing shows a 1/4" spar. I used a spruce spar and felt that the wing was too flexible. I added a second 1/4' basswood spar behind the first. It is 36 inches long and tapered at the ends.

Thanks Ken, Jr. for the pictures

PDFs are of the updated fuselage with the bigger tail.

Build thread is here

Last edited by jb753; Jan 20, 2012 at 08:26 PM.
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Jan 08, 2011, 09:17 PM
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First three

We had 3 ready for the New Year's Day Fly. We had more action, fun and laughs with 3 than we did with 7 in the regular combat. Unfortunately we did not get any pictures or video of the combat.
Jan 08, 2011, 09:23 PM
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Detail photos

The sideview shows the placement of the wing compared to the fuselage. It would be better if the wing were mounted a little further back. I mounted mine at 5 inches from the rear of the motor bell but had to add 1.5 ounces of lead to get the CG to 2 1/4. Six inches from the back of the motor to the leading edge should be right. CG of 2 to 2 1/4 seems good but we are still experimenting.

The wing end view shows the construction of the wing.

Elevon differential is needed to stop adverse yaw. I mounted the servo horn two splines back.

The throws that I am using are:
Elevator High - 5/8 up & 3/8 down
Elevator Low - 1/2 up & 3/8 down
Aileron High - 7/8 up & 3/8 down
Aileron Low - 5/8 up & 3/8 down
Last edited by jb753; Jan 08, 2011 at 09:47 PM. Reason: Correct type
Jan 08, 2011, 09:24 PM
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Shortscut to things later in the thread

Flight performance video - Post 49

Combat Videos - Post 17, 50, 73 (Page 5) (best), 103 (Page 7), 145 (Page 10) - very windy

Pictures of variants - Post 39

Lessons learned - Post 63 (page 5)
Last edited by jb753; Dec 07, 2011 at 08:40 PM.
Jan 10, 2011, 03:10 AM
Hey, watch this!
Raymond-leflyr's Avatar

Nice Design

I subscribed to this thread to keep up with any notes you may post.

Our club already has a one-design club combat model - exact same model, same motor, same prop, same mAh battery (range). The design/concept is four seasons old and you are right, one design makes for better combat. Pilot skill, rather than speed or dollars, is untimately what counts. I forgot to mention 'luck'.

P.S. I would use version 2 of the KF step - 1/4 inch carbon tube actually. My 3-foot wing, spruce-sparred steps flex and bow in hard turns. Looks like it generates its own dihedral when needed (that's my story and I'm sticking to it).
Jan 10, 2011, 07:46 PM
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KOOL! KOOL! I'm building one and have one question??? can I use fiber tape to help hold the spar and make a little easier airflow? OK two questions, as well can I use laminate to strengthen the fuselage/front?? or only balsa/plywood?
Jan 11, 2011, 11:15 AM
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I've built 3 of these so far. Toughest thing is to NOT modify the design significantly. I see no problems with <b>kort's</b> addition of tape other than it might jam up my prop when I give him a good smack......LOL

On <b>JB's</b> I would recommend the addition of a foam plate to the front. Makes a good place to mount the battery using velcro tape and makes adjusting the CG a simple matter of moving the battery fwd or back.
Jan 11, 2011, 07:26 PM
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Bring it on BOY'S!!!!!
Bring it ON! I live to crash!!

" If you never push it to the limit, you'll never know its limits!!"
Jan 11, 2011, 11:19 PM
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Raymond-leflyr - I would like to hear more about the plane and rules that you are using and any lessons learned. I had to double up my spar in the middle of the wing. It had a scary amount of flex but has a reasonable amount with the doubled hardwood spars.

Kort - No limits on how much tape that you can use. My only comment is that I understand the KF wing works because of the step. Reducing the step transition may reduce performance but I have my servo wires behind the step in the middle part of the wing and have fiber tape over the wires and mine flies fine. No other reinforcement of the the wing. No limits on what you use to reinforce the front half of the fuselage but the rear half can not be reinforced.

Forecast is for 50 degrees on Sunday!
Jan 12, 2011, 01:35 AM
Looks like fun! the step in the wing design reminds me of when I lost the top monokote covering off one half of my wing! I was amazed it did not seem to affect the flight!
any videos of this type of plane doing combat?
Jan 12, 2011, 02:15 AM
Hey, watch this!
Raymond-leflyr's Avatar

Combat Buster


PM me with your email address and I'll send you our specs and a drawing.

Its nothing special. Just something that works for our group.
Jan 12, 2011, 06:42 PM
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50 degrees ill be there!
thanks!! Yup I've used sheet laminate to re-enforce the fuselage and as well for the ailerons LOOKS LIKE ITSA GONNA BE FUN!!!!
Jan 13, 2011, 05:14 PM
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Hopefully the weather will be as forecasted and we can get some video this weekend
Jan 14, 2011, 04:00 PM
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John what are you using for propping?
i have most of it down but just cant seem to get the right amount of speed and maneuverability Is it a trade secret???
Jan 14, 2011, 04:11 PM
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I am using a GWS 9 X 5 Direct Drive (not the slow fly). I think that the 8 X 6 DD will also work well.

Trying to set up combat for Sunday afternoon. Looks like upper 40s and light winds.


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