After some digging around in my garage, I came across two sets of combat wing plans. One is for Alvin's Combat Avenger. The plans are in rough shape, but I suppose they should still photocopy ok. The other is called the Spook, which is basically a copy of every other combat wing design with different shaped fins.

In any event, I left Hobbytown at 4:00 today, and by 7:00 I had this:



Then I ran out of CA. :angry:

Tell me about these special modifications you suggest, Alvin. I already remembered one thing I forgot to do, to put a solid balsa block in the center of the trailing edge to give a sturdy place to grip the plane for hand-launching and mounting a streamer hook. I'll have to cut away the sheeting and add that back in there.

I'm debating whether or not I want to go through the trouble of adding the wingtips. Also need to pick up some 1/8" balsa to cut the fins, since that wasn't in the parts list. :angry: Also, which direction should the grain run on the fins? I'm thinking parallel to the leading edge, but just checking. I do plan to run the fins through the sheeting and secure them to the wing ribs, instead of gluing them to the top of the sheeting and having to add triangle stock.

Mike,Slllllooooowwww down.man You got to get ya a BudLight and some pretzels.
In that short of time by lookig at that I am tired.I caant wait to see it.You have probably got Alvin shaking in his shoes right now.Hey,he cheated on combat the other day,just to let ya know.(Mis aligned parts(?)).Isnt that somewhere in the rules?kenny2

I'd like to borrow those plans! :thumbup:
Please! :D
Looking good so far to me! :banana:

That looks like a "Combat Avenger".

With the modern RC transmitters now having the mixing for elevons, I was going to move the two control surface servos outboard some to clear up the central radio compartment for better arrangement of reciever, batt pac, and throttle servo, all in an effort to position the fuel tank in a proper fore&aft position instead of positioned sideways. This would also better position the servos outboard enough to run pushrods to more center attachment point on each control surface, makeing for less control surface flex from control horn to outboard tip of control surface.

That was the major mod I would make, anything to get a proper fuel tank position and perhaps a little larger tank even if I had to fine a plastic bottle of some kind flat enough to fit between wing spars and wide and long enough to hold more fuel. A new style mini servo for throttle would be easier to mount in a new more out of way position.

Yep, the wing tips as shown do make it fly better and the special shape/profile is easiest tip shape to monokote. The curve of the rib and the conture of tip plate are exactly the same so you will have better time of getting covering on easy.
The tips do reduce tip vortex drag for better speed and makes wing tip area produce better lift so it can pull more Gs and make sharper response to pitch commands.
With a low aspect wing design like this, a significant percentage of wing area is near enough to wing tip to really benifit from a more streamline tip shape than just a squared off one.
I remember trying one with just squared off tips and could really tell some difference, enough to be worth the tip construction. Looks better also.

You got a month, take time, make it a nice one.

Running wood grain parallel to leading edge should be fine.
I just butt glued the fins to wing sheeting and it worked OK with none ever flying off in normal flight. The method you describe will certainly be more secure.

Do pay attention to the CG range as it is very sensitive over the narrow range you have to work with.
With empty fuel tank, CG at front edge of wing spar with make for docile, gentle response, but not as active as most would want for combat.
With empty tank, CG at rear edge of spar, very active response to elevator commands, hard to hold steady.
Put CG about middle of spar and be right for most people.

Be nice to see one flying again.

Well Kenny, I have this problem where I can't stop working on something until something makes me stop. In this case, it was the running out of CA. However I did go back out and do a little sanding as well as cut out the access hatch and the elevons. And don't worry, I enjoyed a couple of Miller Lites while I worked. :thumbup:

I plan to leave the elevon servos in the same hatch area, but they'll be moved as far towards the outside of the wings as space will allow. That will leave space to have a mini throttle servo set up in line with the engine to avoid using a flex cable pushrod. I may be able to place the 4 oz tank in conventional orientation, though if I could squeeze in a 6 oz I'd be happy. Otherwise I may mount a header tank alongside the engine. Now that you mention it, I may take some time and look around for anything in a 5-6 oz size that I can fit in between the spars.

You sold me on the wingtips, I'll be building those up when I pick up some 1/8" balsa. Shouldn't take too long anyway.

Did come up with a problem though. I need to use my computer radio for the elevon mixing, but that's channel 58. Johnny flies on 58. I suppose I can bring some extra tx crystals and change the channel when I fly the wing, but I see me forgetting that at some point in time. :o

Mr. Mike, we are thinking along the same lines. :yickes:

See my drawing below of a couple of construction mods to get better fuel tank arangement.
The first mod requires more construction changes, but i can see where it will be easier to fit a six ounce tank as you build the new fusalage box whatever size to hold tank.

I like the bottom mod better as just required to relocate electronics as you described.
Yep, I would like to use a six ounce tank also as the four ounce ones are low on flight time for modern .32 - .35 engines.
As you mentioned, the trick is to find a tank thin enough to squeeze between the wing spars. Someone used to make "Low Profile" tanks that were longer, wider, but good bit thinner top to bottom.
Or one could find a plastic bottle the right size and shape to fit and install some fuel nipple fittings to it.
I used a two ounce header tank mounted on opposite side of engine mount from the engine and it worked OK once you got used to seeing it hanging out there in the wind.

I am pretty sure that the Combat Avenger design will accept one of those new 2.4 gig SS radios and you never have to worry about channels and crystals ever again.
You know that you want one, get it. :yes:

I think I got the tank(s) situated how I want them and it should function okay. Kept the 4 oz tank where originally designed in front of the spars on the right side of the wing, and have a 2 oz set up in normal orientation inside the left wing. Basically the header tank setup, but with both tanks inside the wing. Since the 2 oz tank interferes with the servo rails on the left side, I'll make a half rail that extends from one rib on the left and is supported by the triangle block seen in this pic:



If I feel the rail supported by the rib and the block isn't enough, I can box it to the rear rail or even put a support straight down to the bottom sheeting. The rails on the right side will not be affected. Also, the fuel tubing will exit the wing just forward of the 2 oz tank, as seen in the next picture.

Got the wingtips framed up, slits cut for the fins, elevons cut and laminated (double 1/16" instead of single 1/8") and rough sanding completed.



Gotta go to work for a few hours, so either late tonight or possibly tomorrow I can start in on the finer sanding. Shouldn't take but 20-30 minutes overall, I'm not out for a perfect finish. Covering will commence soon after, and once I receive the new MAC muffler for my .32 I can start sizing up the mount and get it glued in. Should be able to test fly it during the Warbird meet next weekend. B)

Put some military colors on it with a machine gun or two and no one will ever know better. It is rated for combat after all.


Looking real good there, Mr. Mike.

Looks like your tank setup ought to work just fine.
How about heading up my R&D department.

Don't forget to install the antenna tube out through the wing to one tip or the other before covering or are you going the 2.4 gig radio thing?

I know that you know to do this, but don't mount engine to engine mount before you have all equipment installed and covered, then you can shift engine fore & aft some for mounting position to fine tune CG balance.

Mike,
What is the measurement between the top and bottom wing spars?
Too bad I did not keep a copy of my plans, I am lost on this exact measurement.
I am guessing it is around 1 1/2 - 1 3/4 inches.

I was looking at a six ounce Sullivan Flex Tank at hobbyshop today.
Layed on it's side, it was under 2 " high.
It can be reshaped by heating with hot air gun.
I was thinking one could heat it up and squeesh it a little flater and it ought to slide between spars in proper fore & aft position.

I looked at that very same tank yesterday when I was in there. Not sure it could squeeze down flat enough though, as the distance between the spars is actually less than 1 1/2", closer to 1 1/4" really. Maybe we could just seal the whole front rib bay with epoxy and plumb the lines directly into it. Be like a built in wing tank. :thumbup:

If my setup doesn't work like I'm hoping (those little header tanks have almost no clunk movement, so any sustained inverted flight could run the line dry), I'll look into some different options like what you mentioned.

Remember those old control line tanks made from sheet metal?

A tank made of sheet metal like tin or copper soldered together could easily be made to fit that rib bay just right.
Solder in a copper/bronze tube at top of tank for vent.
Find a small metal screw on cap and neck from some metal can and cut it out and solder in the front of our new tank. A metal tube soldered in metal cap for the clunk line and it would be removable for maintance.

For when I ever build another Combat Avenger, I have found a six ounce plastic bottle that will fit just fine. Just have to fit some fuel nipples to it for the vent and clunk line.
Ought to be doable.

Or how about one of those rubber fuel squeeze bulbs.
It already has the tube in it that could be the vent and you could add another tube through the cap/plug for a clunk line.
And it is very flexable and could be squassed down to fit in there easy with the neck end going forward just through leading edge of wing.

Hey Mike,
I think that I may have just found what we need available from Sullivan Products.

Check out this page from their site.
Look at the Oval and Slant Oval tanks.
Looks like the eight ounce Oval or 6/8 ounce Slant Oval tanks would fit as both are 1 1/2 inches thick.
I like the six ounce Slant Oval one.

Sullivan Fuel Tanks Page - Click Here

If they had the normal oval in a 6 oz, I'd be all over it but all they have in the 6 oz is the slant. Not sure how well that'd work laid on it's side. I suppose it should, though.

I was just reminded of my hatred for monokote when it comes to rounded wingtips. :angry:

Cover just the wing tips first.
Do the wing tip bottom then the wing tip top then the wing bottom and then wing top last.

Be easy as pie.

Mike,that thing is looking good.It sounds like Alvin has done some homework also.
You are like me I hate to start something and not finish it soon.i was off drinking for
2 monthes and Billy came out and twisted my arm,i changed from Bud to Miller.But,I
cant wait to see the plane-keep up the great work.kenny2

And progress continues:



That's all for tonight, going to a concert downtown. If I find some time tomorrow I think I could have it ready to go by Sunday, since my muffler came in earlier than expected.

Of course I still haven't even checked to see if the crankshaft is okay on my motor following the last crash, I should probably look into that.

Look's real nice Mike. :thumbup:

I like that covering pattern, looks real nice.

Mike must have built the glider version, does anyone see where the engine goes?

Gonna be too nice to combat with.

That is a fine design :wub: , and builds so fast.

You may be right about that. It's not every day I come across a plane that fits in my little car, I may have to keep this one in one piece and avoid the combat. :D

Looking good!

Ya never said if I could borrow those plans!
CannI Pleeeaaassseee! :biggrin: :D

Yeah Johnny, that's no problem. Lee Hughes has them right now and he was going to run some copies off, I think he mentioned making several of them.

Well, it's getting close. Engine mount is in, fuel tanks are in, elevon servos are in, and I've positioned everything where it'll need to be to balance about right. Need to cut about a 1/4" off the front of the engine mount and fuelproof the whole thing, then bolt down the engine, mount the throttle servo and set up the pushrod, and final install the rx and battery. Got a couple issues with the receiver: First, I don't know where I put that in my original Avenger, but without a mini/micro receiver it's gonna be a tight fit with little room even for some foam rubber. Second, I only have 2 receivers available right now, and both are about 12 years old with questionable reliability. I'm sure they've each been crashed a handful of times. Third, I'm in no mood to buy a new receiver.

Why didn't you bild that thing a little biger so you would have some room to put stuff :banana: :P

:angry:

I broke down and bought a mini 4 channel receiver since I was already at the hobby shop and they had one staring me in the face, but looks like I'm still out of luck. See, because of the channel conflict with Johnny, I was looking to set the wing up using my old Skysport 6VA radio. Unfortunately, everything I can find on how to set up elevons on the 6VA involve having to have the servos plugged into channels 1 and 6. :banghead:

So unless someone knows another way to do that, there's going to be a frequency conflict in combat. Maybe that'll just be the motivation I need to stay out of combat all together. :D

Oh, NO, YOU DON'T!!! :no: :no:

:lol:

Well, as it turns out I bought the wrong receiver anyway. I got a little park flyer Futaba one, so it's back to plan A. Problem is I don't know what plan A was. Squeeze in a standard receiver with questionable reliability? Do I trust it to a good range check? On the plus side, that'll allow me to use another channel like I'd originally planned. On the negative side, well...there's risk of disaster.

Alvin, should the control throws be 5/8" in each direction? The instructions say 5/8" total, so I'm assuming that means from maximum up to maximum down, as 5/8" in each direction seems like a lot. Just checking.

Total both direction = 5/8 ".

Then adjust to your likeing after first crash flight.

Well that's about as clear as you put it in the instructions. :angry:

Are you saying 5/8" up and 5/8" down?

Maybe I am and maybe I am not. :P

I'll take that as a yes.

I figured out what I think to be a pretty good place for the standard size receiver on the left side...problem is once I pop it into place there's no getting it out without some cutting. That makes me a little nervous. But I'll go ahead and get all the setup finished, mount the engine and throttle servo, and do some various range checks before tucking it away for good. This will also mean no changing crystals, so nobody better be planning on competing with channel 60. :lol:

Really I could put the receiver on the right side and still be able to get it in and out I think, but that's just more weight on the already heavy side. Alvin, did you ever worry about lateral balance? I know I didn't care much about it last time, nor do I really on any plane, but I can see how this thing will be pretty heavy to the right side with the motor, muffler, main tank, and throttle servo already over there. My rx battery won't even come close to offsetting all that.

Mr. Mike,
The 5/8 " total throw recomended is the distance the control surface moves from say full left to full right stick movement or full up to full down.

I used to lateral balance by adding weight to light side wing tip area before covering.
All equipment would be in place before covering.

Get it close as possible, prob not all that critical.
On test flight if the heavy side noticably drops when giving hard up elevator command, you can drill hole/s in light wing tip plate and glue in nail/s.

No, Mike.
He's meaning 5/16" up and 5/16" down... <_<

Here is my version. I blew the plans up 18% and ended up with a wing of 42 inches. I hope it will work for a OS 50! The gas tank is in, but it sits on the two spars just on the rear edge. Will that be ok? Or will I need to get it in there so it doesn't touch the spar?

I have copies of the original, and the larger one if anybody is interested.

Lee

It sure ought to go, Lee.
Be interesting to see how the enlarged "Super Combat Avenger" flys.

Would be better if tank was isolated from frame, but we have little choice with the internal tanks on the combat wings.
Carefull prop balancing to keep high freq. vibes to minimum will help keep fuel from foaming.

I see you made engine mount out of plywood.
Be extra carefull with landings, because a little too nose down landing can pop the plywood mount easier than the hardwood beam mount stock.

I cut it so it would lock in between the spars, and epoxied it to the spars, and plywood ribs.

I see that now. :angry:

Regardless, the Avenger is ready to fly. Plywood laminated motor mount and all.

It is almost done!!! Should be done this weekend. Let me know what you think


Lee

Looks good so far :thumbup:

It is done!!! Got the engine installed last night, and all works good.
Balanced it to front of the spar. Hope it flys!!

Lee

Thanks Mike.
If you could, tell Lee to give a set to Alvin to hold for me when I get back Offshore? :parachute:
I would really appreciate it. :thumbup: