Set up qestions

[Curare]

Ok guys, I've just come back from a good morning's flying on my little sport model and it's raised a few questions.

I figure I should ask the guru's rather than people who are possibly as ignorant as I am.

So, lets kick off.

My little model is a bit porky for it's size, around 16oz for 275 squares, with a well worn PAW 149 towing  it around in a circle.


It'll loop, fly inverted, and do lazy eights relatively well (about my skill level at the moment).

What I am finding is that it seems to run out of puff and want to fall in on wing overs, and squares, well, aren't.

I have adjustable leadouts, would winding the leadouts more aft help with the wingovers?

I was flying it with a forward CG and it would loop but corners were horrible, so I shifted the CG aft, the corners got better but now it hunts, should I go  forward on the CG again and  mess with my line spacing?

[Steve Helmick]

You might be able to get rid of the hunt by sealing the hingeline (elevator only, I'd guess?), and/or by moving the LO's around. Small model, I'd guess 1/2" behind the CG for the mid-point of the two leadouts...but fiddling should make it better. One change at a time!

What are you using for lines? I'd go with .008" braided lines about 42', but might try Spectra fishing line of about 30 lb test. Beware of the knots...they're important. There's some info on the 1/2a forum about using them.

MAJOR deal is to try a variety of good propellers...Taipan, APC and Graupner make good stiff plastic props. If they don't break when you smack it in, they're not good props. Most wood props are crap without a lot of handwork. The really good wood props don't come in small enough sizes for your 1.5cc. 

If the plane has a landing gear, can you do without it? Big gain in performance to be had there for small models.  Steve

[Curare]

Steve, thanks for the input. OK, lets go!

1. hinge line is more open than I'd like, so I'll try sealing that for a starter.

2. I set the LO position to get me around 2° behind the CG, as a rough starter point. I'll seal the hinge line first before I mess with LO again.

3. I'm using 25lb spectra and 48'. too long?

4. Now, propellers. I'm afraid I've busted all my good ones! I was running a 7x5 on it to good effect (or so I thought), but broke that messing up. So far I've found an 8x3 is barely adequate to get me through a loop, and a ye olde TF 8x6 doesn't seem to have much more speed than the 7x5. Would I be right in assuming a bit more speed with help with the overheads?

I'll check out another LHS on the way home today to see what I can scrounge up, but I have a few 7x6's and 7x4's floating around in the 'prop drawer'.

[Steve Thomas]

Hi Curare, your model is not really porky for its size - it's actually got quite a low wing loading by CL standards, so this shouldn't stop it turning well.  16 oz is fine for a PAW 149, but 275 sq.in is getting a bit on the big side IMHO.

I wouldn't bother with the 8x3; 8x4 is pretty good, and a 7x4 works very nicely.  The little PAWs don't mind revving, and don't need a big load on them to do well.

Steve

[Jim Thomerson]

I think you need to move your leadouts forward for more tension upstairs.  Move them a little at a time, like 1/16 inch on a model of your size.  Probably a 7 x 4 prop is going to work the best, but experiment around, as one can be surprised by what works best.  Make sure you are not overcompressed.  If overcompressed your engine will load and slow down in maneuvers.

[Steve Helmick]

To be clear, when I wrote .008" braided lines, I meant braided stainless steel cables. They're pretty delicate, but I think might outperform the Spectra lines. That said, I haven't tried Spectra lines for flying models, only fishing. I would avoid the "fuzzy" types, and go with a tightly braided one, like Power Pro or Tuff Line. Again, knots are critical.  Steve

[Tim Wescott]

4. Now, propellers. I'm afraid I've busted all my good ones! I was running a 7x5 on it to good effect (or so I thought), but broke that messing up. So far I've found an 8x3 is barely adequate to get me through a loop, and a ye olde TF 8x6 doesn't seem to have much more speed than the 7x5. Would I be right in assuming a bit more speed with help with the overheads?

I'll check out another LHS on the way home today to see what I can scrounge up, but I have a few 7x6's and 7x4's floating around in the 'prop drawer'.

I don't know how things are over there, but over here I pretty much need to order props.  This in spite of having a pretty good LHS in town.  I can get the right props for bigger engines maybe 1/3 of the time at my LHS, and for 1/2-A I just need to order special.

[Steve Helmick]

APC has 7-4, 7-5 and 7-6, Thunder Tiger has 7-5.5 and 8-4.5, Top Flite has Power Points in 7-4, 7-6, 8-4 and 8-6. I haven't been able to find a source for Graupner props anymore...Hobby-Lobby used to carry them <sigh>.

I think the 8" props I've listed might work, but would likely need trimming down some. Maybe a new skill to learn, but a valuable one! Some have looked at the prop on my .46VF/tuned pipe stunter and asked what the Dickens prop that is...looks wicked, works wonderful! Started life as an APC 12.25 x 3.75, clipped to 11.5 and much reshaped. Shockingly easy to do, actually.  Steve

[Curare]

Thanks guys, I'm pretty used to reshaping props these days, nothing ever seems to work quite as I like it. I managed to get a 7.8x4.1 from the LHS (which has the most rediculous props to chose from, who would use a 7x10?!) and found a few 7x4's and 7x5's to try too.

CL is a new experience for me, I've been knocking around flying RC pattern for years.

It's another beatiful morning, so I'll get some laps in before work, and we'll see how we go.

[Steve Helmick]

Well, nobody ever made props without a market. The 7-10's were very typically used for .29 speed. Controline, of course.

Now, you can hardly buy a .29 of any sort, but by God we have .21's, .23's, .25's, .28's, .32's, .34's, and .365's, and very few of them will rev over 20k without barfing their guts. If they do rev up, they're configured for R/C cars, with pull cord starters we'd need to delete,  and weird crankshafts that won't hold a prop without some creative machine work or parts bin searching.    Steve