Delta
 

Is it wrong to enjoy the smell of a dremel wheel cutting through PVC?

I found a picture of a delta wing SPAD that I thought looked really cool, so I decided to imitate it. This thing has a 24" fuse, 36" wingspan, a music wire stiffener, and 8" stabilizers. I am planning on powering it with a .25

RE: Delta
 

This was the guy that gave me the inspiration:

http://www.flying-models.org/discussion/cororoo.gif

RE: Delta
 

Looks good!:D
Austin

RE: Delta
 

Don't think a 25 will have enough power
Most people are using 46 and 47 size engines on the CoroRoo and BullDawg.
The pic of the CoroRoo You posted, has an ASP 52S with purple pipe running on an APC 11x9 and taking the manifold down to about 3" made a huge difference to the rpm!
You can find the entire build thread and plans at( You'll have to register to log on )
http://www.spadcombat.co.uk/spad/
In the SPAD Builds and Construction forum on page (4) topic miniCororoo

Jeff

RE: Delta
 

I think a .25 will be enough, look at my delta on post #3 of this link http://www.rcuniverse.com/forum/m_6960015/tm.htm it's a 36" span and weighs 43oz and it's only got a .15 on it, while it's not a rocket it does fly good.

RE: Delta
 

Thanks for the advice, both of you. My airframe is weighing in at about 28 ounces, with the elevon servos installed. It will be right around 2 pounds when I add the RX, battery, and throttle servo. With an engine, the weight should be pretty similar to Microsprint9's bird.

I know that most of the guys building these things are looking for extreme speed. I am looking for a fun flyer that looks different from my other planes. I have a couple of engine choices that I can borrow from other planes. I may try it with the .25FX from my combat spad, and if that won't fly it, I'll try the .46LA off my Four Star. I've been thinking of going to a four stroke on that plane anyway.

Here is a picture with the elevon servos, firewall, and some decals.

RE: Delta
 

Sorry, didn't realize You were building a CoroRoo Light version.

Hope to see a flight report soon.

If it flies as good as it looks I might have to build one too [8D]

Jeff

RE: Delta
 

Looks like fun. It looks to me that the fold in the verts follows the fuse cut out. If that is so, they will act a bit like down elevator because they are basically a v-tail. Watch for that on launch. It might try to nose in on you. Take another look at the cororoo, and see that the fold in his verts is parallel to the wing. Good luck with the maiden.

RE: Delta
 

Good catch. I missed that.

Any advice on where the CG should be on this thing?

RE: Delta
 

You can download the original plans for this plane at http://www.spadcombat.co.uk/spad/ind...fileinfo&id=97

RE: Delta
 

Thats a fine looking delta, Mclina, good luck with it!

Smooth

RE: Delta
 

Despite the disparaging comments (and puking smiley) over at Spadworld:

http://spadworld.net/forum/viewtopic.php?t=15166

I have decided to press on with this thing ;)

I mounted the engine and fit the RX and battery inside the fuse. I reworked the stabilizer mounts to level them out, but they are still a bit crooked. I have a bit of work to do to straighten them out, or I may go back to the drawing board back there.

With everything on it except a couple of screws and pushrods, it weighs exactly 3 pounds. The way our weather's been, it could be a month before this thing gets in the air anyway.

RE: Delta
 

When Your building a new design some people can't handle it and would rather put You down instead of encouraging You to succeed.
Don't let it get You down.
Sounds like Your getting close to the maiden flight.
Eagerly waiting the flight report.
As for the vert stabs, on the CoroRoo they put coat hanger wire in them to get them to hold there shape.
You could also just make a "V" tail out of one piece of coro for the tail feathers.
Jeff[8D]

RE: Delta
 

I like the V tail idea. The whole back end is a bit floppy as is. I glued in a piece of yardstick to stiffen it, but if I made a big V out of the stabs, it would tighten it right up.

Thanks

RE: Delta
 

Mclina:
That's a fine looking delta...good luck with it. I built a bulldawg a couple years ago and never had much success with it, but most people seem to have good luck with the delta's in general. Looking forward to your maiden report.

Smooth

RE: Delta
 

The V tail was a great idea. I think it looks a lot straighter now. I also fixed the wing - if you look at the original wing bottom picture, it was not symmetrical. I didn't realize it until I had the striping tape on. I took the tape off one side and fixed it.

All it's missing now are the elevon pushrods. It is balanced about 1/2" in front of the CG on the cororoo plan. I think I will leave it there for the maiden flight.

And it's snowing like crazy outside.

RE: Delta
 

mclina:

I've been following and reading your thread and have built a cororoo too !!! I have a question about the construction of the elevons though.

On the plans it says

"Once the flaps have been folded over and glued, the elevon outer skins can be
made, cut a strip of 2mm corro approximately 76mm wide, flutes running the
76mm direction, and long enough to make 2 elevons. Score a center line and
and fold over, exactly as you would do when making a wing leading edge, these
are then glued to the elevon hinge parts, as per the pictures in the build thread.
This first "

I've folded over the top flaps, but am unsure how the elevon outer skins are made and attached. When I glued in the 4 mm. elevons between the top and bottom skins, I thought this was to be the elevons. Is there to be a 2mm by 76mm top skin glued to the top of this ?

I'm anxious to hear about your maiden flight !!! how are you planning to launch the cororoo ? Possibly hand launching like the PBF ? Looks little scary with a screaming .46 on the nose !!!

Best of luck-And by the way, your plane looks awesome!!

Cary

RE: Delta
 

Hi mclina
Nice looking plane. Does your wing have an airfoil crossection or is it flat at the top and the bottom?

RE: Delta
 

It's just a flat wing, a single layer of 4mm coroplast with a music wire stiffener. It isn't built the same as the Cororoo plans, it just has the same dimensions. It's probably more like a PBF.

I am planning on trying an underhand launch. I'll see how much pull it has when I fire it up and decide from there.

RE: Delta
 

Thanks mclina!!

Best of luck on the hand launch. I was thinking of doing the same with mine

RE: Delta
 

Yes , 2mil folded and wrapped over and glued to the top and bottom of the 4mil elevons , it helps stiffen the elevons and makes them even with the top and bottom skin.
Making the elevons 4mil thick.
Jeff

RE: Delta
 

Last picture, I promise. I added some stripes to the tail, and took a shot from the side to show the profile of the stabilizers. I installed the elevon pushrods and programmed the radio. It is now 100% ready to fly. We got 8" of snow last night, so it will be a while before the maiden. I will have one of my kids shoot a video of the maiden, and I'll post it if it's not too embarrassing. OK, I'll post it even if it is.

Thanks again for all the good advice.

RE: Delta
 

Thanks Mr GreenSpeed !!!! It makes sense now.

mclina: Looking Good !!! Can't wait for the maiden on it. Keep us updated.

Cary

RE: Delta
 

Sorry about the puking smile thing.

The fins just didn't look right in the first picture you posted, but it looks great now. I wasn't trying to put you down or discourage you.

I've edit my post on spadworld and now publicly apologized. Sorry man.

I'm anxious to hear how your maiden goes.

I always worry about tossing any of these underhand, I can't get up nearly enough "umph" as I can overhand. It usually ends up pretty squirrelly from the toss to the sticks.

On totally trashed my GMS .32 on my sickle on two bad tosses, but I'm sure that was more a CG issue than anything else. I'm using a .40 on it now and it flys great. But it gets small really quick.

I'm concerned about this plane too though because it doesn't have a traditional airfoil and I've never flown a flat airfoil.

Anywho, keep us updated on the maiden. Best of luck!

RE: Delta
 

Hey, no problem. I thought it was funny. I knew there was something wrong with the fins, I just couldn't figure out how to fix them.

I haven't flown a flat winged plane either, and I also wonder what keeps them in the air. I am very curious to see if this thing will fly.

Thanks for the encouragement.

RE: Delta
 

Hi mclina
That first takeoff will be a challenge. I learned to fly in the winter in PA. Eight inches of snow makes a good cushin for a bad landing. I would welcome the snow for the first test.

RE: Delta
 

Has anyone put a set of main wheels on the cororoo and a steerable nose wheel ? It wouldn't be hard to do.

I too am aprehensive about hand launching a screaming .46 OS AX with tuned pipe. With the landing gear, it would be in more control until speed was built up for takeoff, and once trimmed out and flight characteristics learned, the gear could be taken off if desired for hand launching. Just thinking out loud here.

What should the cororoo weigh in at ? Mine is 4 lb. 14 ounce total weight.


Cary

RE: Delta
 

I'm hoping for a little over 3#. I'm at 85% with a coro fuse.

I think adding gear would fatten the plane up a bit too much. It's supposed to be a flat wing and then you'd be adding landing gear hanging down there creating all that drag.

I'm building this plane for all out speed , so I'd rather take the chance tossing it.

Just make sure you're CG is dead on, and you should be fine. Once you get the trim worked out, the launch will be easy. It'll just takes a firm underhand toss if it's like the sickle.

The other thing about gear is that this will be landing pretty fast I'd imagine, and I don't want to bounce it in.

I'm used to making a low sweeping approach, and with the sickle I couldn't do that. It got really tough to control at low speeds. I had to come in low and fast and just chop the throttle into the grass.

My biggest concern is the size of this thing. I'm at 30" wingspan. How fast will that be out of sight at 100mph?

RE: Delta
 

at 30" wingspan going 100+ MPH, DON'T BLINK !!! or it will be out of sight. I built mine to the 36" wingspan as per plans, so mine is heavier at 4lb 14 oz. with OS 46 AX.

I'm use to hand launching the PBF's with OS .25 FX, and they hand launch fine. This looks like more of a challenge to hand launch though. I suppose a quick underhand hand launch is achievable.

I would like to see a video though of someone hand lauching the cororoo, it would give me an idea of what to expect.

Cary

RE: Delta
 

http://www.spadcombat.co.uk/spad/ind...c=select&id=15

A few videos in there, the first one shows the hand launch.

How did you get the 36" wingspan? The 36" wingspan made mine too long to fit on one piece of 2' x4' coro. I'm guessing you have 4x4 or 4x8 pieces?

I wish I could get 4'x4' pieces shipped economically.

I'm assuming that would be really expensive? I usually get the 2x4 pieces for that reason.

RE: Delta
 

xray:

I had to splice a 3" section at the end of a 2' x 4' 2 mm. sheet to get the 36" width. I know you said in a previous post this might make it less stiff, but I took the chance.

the 4 mm. internal core is one piece though (acquired a 4' x 8' sheet through a local sign shop), and glued the 2mm outer pieces with splice to this. The sign shop couldn't get 2mm 4'x 8' sheets.


cary

RE: Delta
 

Today looked like the best weather day I was gonna get for a while, so I took this thing to the field at lunchtime. There was still about 4" of snow on the ground, it was about 35 degrees and dead calm.

Three times I gave the thing a firm underhand toss at full throttle, and three times it made about a 50' arc right back into the ground. At no time did it feel at all like it wanted to fly. It didn't seem to respond to the elevator at all, and I never really had time to give it any aileron input. At full throttle, it felt like it wanted to pull out of my hand, but it didn't want to climb after I let it go.

So, what do you think? Could it be nose heavy? Is it just underpowered? Could it have been my launch technique? It is balanced at right around 10" back from the front of the fuselage.

And the snow probably did save me one prop. I broke two on the three launch attempts. Other than that, there was no damage.

Thanks in advance for your advice.

RE: Delta
 

Hi mclina
You state "50' arc right back into the ground". Is this an inside loop? If yes, my guess is tail heavy. If there seemed to be plenty of engine power, you might try less throttle next time to give a little more time for correction. Maybe a click or two of down elevator. If it is an inside loop, you might consider having someone with you. I have no experience with a delta.

RE: Delta
 

No, it wasn't a loop. It just went up a little bit, then nosed into the ground about 50' from me. If I had thrown it without the engine running, it would probably have done about the same thing.

The CG is forward of that was called for on the Cororoo plan, by about 1/2", maybe closer to 1".

I have hand launched my combat SPAD, which weighed the same, and used the same engine, and it climbs like crazy. There must be a trick to getting a flat wing to fly. Perhaps it is just way underpowered, like I was told by GreenSpeed way back in Post #4:D.

RE: Delta
 

I'd suggest getting a buddy to give it a good firm toss. Maybe the engine doesn't have enough power to get it to flying speed. My sickle was like that on a .25FP, it would really struggle to get up, but then once it was in the air it flew ok (just barely). At least that could help rule out the design or CG as the problem.

What diameter prop are you using? Maybe increase the diameter/reduce the pitch?

How much throw did you have in the elevon?

Maybe reflex the elevons?

What was the final weight?

RE: Delta
 

My dry weight was 48 ounces. The first prop I broke was a 9x6 and the second was a 9x5. The elevon throw was about 3/4" in each direction.

RE: Delta
 

6 oz tank? So wet you were around 54 oz?

How about trying a 10x5 prop? That FX can handle it.

You need as much "umph" out of the hole as you can get.

RE: Delta
 

Something must be wrong with either your engine or the CG, my 36" span delta weighs 42oz dry, has a 4oz tank and flies great on a Magnum .15XLS with a 8x3 prop, in the second pic you can see a pc. of coro glued to the bottom, this saves the prop on landing and gives you somewhere to hold on to for a good launch, my friend has one almost exactly the same as mine but the span is only 32" and it easily gets in the air with a slight underhand toss.

RE: Delta
 

Dumb question, the prop is on the right way, right ? and it's not a pusher prop ?

RE: Delta
 

Your cg is half to 1 inch in front of the roo cg dry. Think how much it is when full. Try to get the CG in the right place.

Also, the FX I think has more lug than you'd expect, try a 10x4 and then 10x5 but I'd think the 9x5.6 should have done it.

Get that CG right and see if that doesn't fix things. If you have the CG too far forward, you won't be able to pull that nose up anyways. You might try launching wiht just an ounce or two of fuel.