Tiger Moth, flying inverted and 9x7 vs 10x4.7 props - RC Groups
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Oct 21, 2001, 08:08 AM
Most Exalted Windbag

Tiger Moth, flying inverted and 9x7 vs 10x4.7 props

I had the Moth out this AM in no wind and compared the two props. I still like the 10" for general flying. I can putz around at 2/3 power a lot better. The 9" requires closer to full to climb.

It loops better with the 9". With the 10" it tends to go off course a bit. May be my trim and may be torque. With the 9" I can do three clean, straight loops in a row. Probably more if I were higher to start.

Did great flying inverted. I just pushed down on the stick at the top of a loop. Slightly lost altitude with the 10" prop and didn't lose any with the 9". I flew it that way for up to 10 seconds. The problem was that I couldn't turn and by that time I was getting too far away toward some trees. I just finished the loop to get upright.

Cool plane!!!

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Oct 21, 2001, 09:06 AM
Registered User
Bleriot's Avatar
Hi Red Baron 47. Up early I see. Been out since dawn! I'll bet the 10-4.7 is best for dead calm and indoors. I'm not using it so as to preserve my Tadrians! I seem to prefer the 9-7 for outside and wind, also ground clearance, Clarence! I seem not to have enough travel for sustained inverted. To do so , I have to (at altitude), feed in full down trim, which starts the dive into the loop, and then it works, but steering is a problem. I also have to remember to neutralize the trim after these idiotic antics. It's amazing how 10 cents worth of foam turned into such a rock stable slowflyer! Well I'm off to build a 6 cell AAA nimh. I found I liked the loading of the 6 cell 300 nicad for wind management, and this oughta give some great duration. Kinda cool out this morning,huh? Best Regards
Oct 21, 2001, 09:19 AM
Most Exalted Windbag
Cool? My fingers froze. I flew the Moth for 20 minutes and quit. I wanted to fly the B III, but not without gloves. I have some of those form fitting ones with little sticky octopus suckers I used for fishing. Now if I can only find 'em.
At least our motors were happy.

You just need to adjust your throws. Don't you have a computer radio now? If you don't do it with the linkages, you could just dial in 125%. I have mine set so the control surfaces just miss touching each other at full throw. I use a dual rate of 60/100. 60 for landings and calm cruising and 100 for going nuts.

Last edited by Red Baron 47; Oct 21, 2001 at 09:24 AM.
Oct 21, 2001, 09:26 AM
Registered User
Bleriot's Avatar
Ok so it was freezing, my feet are just now thawing out. This is excellent for the motor though, they barely warm up in these temps I put roundels on the underside of the lower wing, really sets it off nicely. Also the birds are scared of all the "eyes". Got another spare TM yesterday, guess I'm hooked, huh? Best Regards
Oct 21, 2001, 09:36 AM
Most Exalted Windbag
I was going to edit my post. Glad I didn't since you already read it.
"I'll bet the 10-4.7 is best for dead calm and indoors. I'm not using it so as to preserve my Tadrians!"

I saw your measurements in another post showing high amp draw. Here's what I got static on the plane through the Pixie ESC.

9x7" prop, 1.9 A, 15.0 W, 7.7 V, 4.5 oz thrust
10x4.7" prop, 2.0 A, 16 W, 8 V, 6.5 oz thrust.

I think I'm ok and "going for it."

Oct 21, 2001, 09:42 AM
Registered User
Bleriot's Avatar
Hey Hi . Are your measurements done using your beaten Tadriand or did ya ever get some new ones? Could be yours have diminished capacity. I used a pack of new cells for the test. What Lith charger are you using? Best Regards
Oct 21, 2001, 09:42 AM
Most Exalted Windbag
I'm posting another since you're so fast.

You got a spare TM, I got a spare Cub. I screwed up the fuse on mine by not applying the paint thin enough and ate the foam. I was going to try and get just a fuse, but don't want to wait. I may be glad I have a second set of wings if I ever crash it good.

I have the ailerons cut from the wings and built them with no dihedral. I'll add just a tiny bit when I install the struts. Lookin' good so far. I made out ok when I painted the bottom of them.

Oct 21, 2001, 09:47 AM
Registered User
Bleriot's Avatar
Hi Well the spare TM is in storage, just waiting for the new GWS linear 4 gm servos to be put on the market, got a two wing aileron scheme in mind. What charger are you using? Best Regards
Oct 21, 2001, 09:48 AM
Most Exalted Windbag
It was through the beaten ones on another plane; the infamous Gnat.

I have new ones in the Moth, I'll measure them as soon as it's charged up.

I'm using the Magellan charger. I also have a little one I got from Todd, but haven't put connectors on it yet..

Oct 21, 2001, 10:24 AM
Registered User
Pat Daily's Avatar
Red Barron

I have tried to fly my TM inverted several times, but I don't think I have enough down as she goes into a pretty steep dive when on her back with full down elevator. Maybe I should apply down earlier in the loop. I too have tried the 9 and 10 inch prop and like the 9 for most of the flying but the 10 is great for getting her off the water when she is wearing her floats. I also tried a "c" drive with different size props up to 11 inch. The c ratio should turn bigger props at lower amps. couldn't really tell much.

Oct 21, 2001, 10:29 AM
Motors beat engines!
I'm just about to try this comparison on the litestick between these two props based on input from motocalc.

According to motocalc on 7 270 nimh:

10x4.7, good thrust static, but barely enough speed to remain airborne. My flight impressions reflect this, close to wide open throttle to cruise around, runs about 10 minutes. Takes off in about 3 ft from hard surfaces.

9x7, predicted lower initial thrust but top speed way up. Climb rate ( not angle) up over 50% over the 10x4.7, flight time should be up about 1 or two minutes. Full throttle current draw down 0.1 amps over 10x4.7. In flight current down even more just becouse you can throttle back more.

My LHS finally got in some 9x7's so I will be putting this to the test as soon as we have a calm day. I'll post about it when I have results.
Oct 21, 2001, 11:19 AM
Most Exalted Windbag
Pat and Bleriot,

I don't know about you guys, but I didn't follow the instructions and cut all the way through my rudder and elevator hinges, then angled the side on the control edge. I thought merely bending the foam would cause binding. I just have a full length tape hinge with short tape backups at the horns. I also have flying wires that make my wings as stiff as an old pair of gym socks. As I said, I have full throws just short binding. Maybe that''s the difference in the inverted characteristics. I wish I could turn though. Maybe need more practice.

I just applied full down pretty much at the top of the loop. Didn't really think about it. It worked the first time.

Sounds good. We need all the data we can get.

Oct 21, 2001, 12:38 PM
Most Exalted Windbag

I tried measuring my amps, but can't get a reading going from the battery to the ESC connection on the outside of the plane. I don't have a quick release cowl as you do and I'm not sure I can even get to the connector from the ESC to the motor then. Might have to remove the wings. Too much trouble.

I'll be using the 9x7 for now anyway 'cuz I want to work on my inverted flight. See if I can steer it. Also when I use the 10x4.7 I rarely use more than 3/4 throttle.

Gonna see if I can fry eggs on my Tadirans.

Oct 21, 2001, 01:29 PM
Registered User
Frank's Avatar
Inverted! You're the man!!!

Thanks to Basketcase, I downloaded the FMS Moth and have been preparing for my own TM first flight. I thought the performance of the sim version a little generous and altered my .Par file to what seemed right. The only response I've been able to produce trying rolls or upside-down flight is SPLATT!

If you're painting yours, get the Testors Model Masters ACRYLIC paints. They're non-toxic, water clean-up paints, do a good job and won't eat foam. I'm using Turn Signal Amber on my Moth. Not a good match for the factory lemon yellow, so I'm giving all surfaces a light coat with an airbrush. Just make doubly sure it's the ACRYLIC paint.
Oct 21, 2001, 01:44 PM
Most Exalted Windbag
Hi Frank,

I guess I'll have to bite the bullet and use an airbrush. I have one from my glow days 15 years ago, it's just a matter of finding all the stuff. I haven't seen any acrylics in spray cans.

I ordered some Goldberg Ultracoat that says it's ok for plastics. We'll see.