Comet Aeronca K

[Megowcoupe]

Hi

Well, I seem to be on a seaplane kick. First I finish off the Leveque, and now this....

I know I'm not the only one that built this airplane awhile back and never flew it- well at least on rubber- never could get it to fly. My brilliant plan was to fly it off water, but it really dawns on me that FF off water is a PITA. The tail surfaces were pretzels- nice light wood doesn't deal well with doped tissue, and I've never made an airplane with potato chip tail surfaces fly worth a plugged nickel. Anyhow I had this airplane lying around for years, and I finally decided to do something with it. I grabbed an LPS B, pair of Kokam 145 cells, 5 x 3 GWS prop, and a pair of Cirrus 4.2s. Access is through a hatch in the bottom. A bit of Dremeling on the LPS mount, and it's a bit lighter and fits in the nose fine. All up weight is about 1 3/4 oz (no my scale isn't more accurate than that- and it's an easy +/- 1/4. With this setup, the motor draws about 0.5A for about 4 watts of power.

Got to fly the airplane with Chris Parent indoors yesterday at the Glastonbury High School gym-(post rubber meet). With a nice hand launch (skids on the gym surface, but not enough to get off) began making a few laps in the gym (basketball court size). Plane turned better to the right than to the left- something of a warp in the left wing, which hopefully is now fixed. However, it's got enough power to climb gently- needed to reduce power to hold height- but you can't really rack it around. I have a hunch it has just enough to get off the drink, but that's gonna have to wait too.

Sam

[jrb]

Wow Sam, that’s beautiful!

Tempting me to change from finishing the CG Shoestring (about 85% http://www.rcgroups.com/forums/showpost.php?p=2838324&postcount=10 & http://www.rcgroups.com/forums/showthread.php?t=291938&highlight=shoestring ) and pulling my K out of its storage box.

Wonder what shape its in and if the tissue has held up; been in that box for 20years.


I’ve got a 2S145 and the Cirrus Micro Joule set-up (RX, ESC, & Servos - http://www.hobbypeople.net/gallery/443414.asp ); what RX are you using?

Do you think the AeroMicro planetary would fit ion the nose ( http://www.aeromicro.com/Catalog/planetary_gearbox__2_0_g__with_5_1_gear_ratio_1247 318.htm )?

BOL,

Jim

[Megowcoupe]

Hi Jim

I've had tissued airplanes last that long without too much deterioration- may depend on what dope you used, how they were stored etc. I'm just using a GWS rx with Azarr antenna and a pair of Cirrus 4.4s.

Don't blame you for wanting to go to one of those boxes- the mounting setup is easier. Not sure which is lighter though. My airplane needed solid balsa tail surfaces to balance out the motor in the snoot (batteries are close to the cg- servos a little behind) so weight is a bugaboo in the Aeronca. If you want more zip, you could probably just go to the A drive- don't remember the gear ratios though. The Aeromicro box might be closer to the A drive in ratio anyhow. Do like the 5" prop though- might go higher in pitch if I need more oomph to get off the drink.

I kicked around one of the HY 50K motors I had lying around which uses that gearbox. I don't know what motor is in that setup, but I have a hunch that gearbox has more drag than the LPS setup. Reason? I put a whattmeter on the motor which was turning some random 4" prop I had lying around. (Was sold as an e prop.) Pulled about 0.8A or a bit more kind of remember 7-8 watts. Gearbox made lots of racket, but there wasn't a lot of pull out of the setup. Either the motor in the gearbox is wildly inefficient on 2 cell li-polys (could be, was originally intended for 4 cell nicads) or the gearbox itself has lots of drag. The LPS B setup at 4 watts made less racket but produced a lot more breeze with a 1" larger diameter prop (no measurements other than a Mk 1 Sam finger meter.) Word around was that the K wasn't much good for anything- I can believe it. Since I've occasionally had gearbox binding issues with other motors in these boxes, they worry me a bit- they're also fragile. However, one of my first successful little electrics used the HY 50D motor and a 2 cell Tadiran setup that was just fine so go figure. I also liked the B motor and a 3 cell li-poly before I dorked it. I think in the higher watt setups, the gearbox drag isn't as noticeable- and I think at some point, you showed me some data which indicated that gearbox drag doesn't increase linearly with watts.

I think there are also 3 motors which are stuffed into the LPS boxes- I'm pretty certain I have the high V motor with the lower A draw. I suspect this is a good motor for the Shoestring. Bear in mind that I'm only running at 0.4A- if you need to, the motor is rated for an easy double the draw. I suspect 8 watts will haul that Shoestring around smartly if it's light enough.

The other alternative is the HY-50F setup which flies my Skylark- it's about 30" span and definitely not a lightweight with a 6 cell pack of 300 mAH NiMH cells in the snoot. This is a somewhat larger motor than the K (do you need noseweight?) and handles around 1.5A IIRC. This would be for an even zippier Shoestring, but I'd worry that the weight might get uncomfortable. Glad to see you've discovered cell lighter than the Kokam 340s- wild overkill in these applications.

Sam

[jrb]

Wrote about the 340s before ever holding one in my hand! I asked the guys “got something smaller” when I was going to buy; so I got the 145.

Think I can use port #2 on my 330d to get to .1amp for re-charge; have used lowest setting on the regular port for top-off as it goes constant volts pretty quick.

With an N20 and a Dare 4.75 rubber prop (its really plastic!) I get 4watts on .6amps; and the Shoestring spinner fits. The GWS props just seemed to be too flexible and light on pitch for the Ol’ #16.

Larger diameter is a better choice for the Aeronca.

Will finish the String, and the maybe the K some day.

Never finished my Jr. back in the early 70s; remember it as maybe heavy! Specifically the triangle stock on the fuselage corners. Your’s look great as a twin; dreamed of doing it that way, way back then.

Wonder what my Dad did with it, was all framed up! He probably got rid of it and a lot of other plane my sister (her son is Jason M - EFlight/TP fame), brother (Shortie), and I left in the basement.


Hope to see some flying shots of you K! Wonder how we cold get a spot of water in a gym; need more width than a trough though.

[Megowcoupe]

HI Jim

Just grabbed a quick tach reading on the K setup- GWS 5 x 3 is turning at 6400 rpm on a pair of 145s HOC. One possible setup on the 'String is to go to a 5 x 4.5" GWS prop (or whatever it is) which would increase the pitch speed without upping the wing loading too much. My problem is that I never flew those airplanes and don't really have a sense of what they weigh relative to the K. If much heavier, you may really want a bit more than 4 watts.

Thanks for the kind words on the Skylark Jr. This was something a buddy of mine talked me into- he loved the plane as a kid, so I first found him an original kit, then we bought a pair of the laser cut versions. The newer versions have much nicer wood and go together much easier, but since they don't have much triangle stock- you can't round them very far.

I figure there are enough ponds around here for me to kick around flying the K outdoors when it warms up- I've got the Leveque as well as the Pondscum, so I can really plan a flying session around water. (Hate having only one airplane for an outing- kill it and you're done.)


Sam

[jrb]

What’s a “pair” Sam?

At this point I read it as two “Y’d” 2Ss; didn’t really look at it in that detail earlier.

With a Gunther the N20@5:1 on 8volts does 5640rpm, .8amps = 6.4watts; previously listed 145 data was also w/G.

The Dare is the same size prop as stock on the String; and turning more revs than with rubber IIRC -- any idea how many watts from the stock elastic? A rubber to watts chart! A square prop & more revs than G w/145.

So, I’m feeling pretty good about the feeling/breeze; weight should be OK.

I have a big hill near my house with lots of acres below; when I flew my A-10 (GWS) and EDF’d Sonic I landed below. Probably will do the String there 1st just in case.

Went from 8 to10 on the A-10, like 3S even better -- ROGs nicely; bad Gen2 on the Sonic ROGs too nicely now.

Didn’t get either the canopy of gear wire for the Ol’ #16; have even though about not doing wheels. May wind up doing Tribute type pants in the end; high lighter worked OK for yellow, though Den told me I should have left it raw. I’ll post success or less in the other thread.


Thanks for the input on a set-up for the ShoeString; kind of the other end of the spectrum of what’ve done.

It’d be great to see some pics n vid of the K of a golden pond!


Jim

[Megowcoupe]

Hi Jim

Let's see- a pair is just a 2s 145 pack-not a 2s y'd. Sorry for the confusion. Think we're running the same cells.

Your data on the N20 sounds very similar to the HY-50K motor- wouldn't be surprised if it's the same thing. I think the gearbox is trouble with these small motors- got too much drag. I have a hunch the LPS gearbox is less power hungry.

In terms of props- over the years, I've gotten somewhat underwhelmed by most stock plastic props intended for rubber power. Since I just got whupped in WWI peanut by somebody flying a Fokker M something or other (Austrian biplane) which actually didn't look all that different from my Ansaldo (well, it was a lot prettier- Tom Nallen can build)- with one glaring exception- he was using a 5.5" Peck prop radically thinned down, both in chord and blade thickness. This is also much lower pitch than what I'm used to seeing in rubber FF (I'm used to P/D of 1.3:1 or so typically rather than 1:1 on a lot of winning airplanes)- but the airplane few beautifully, and I wouldn't be surprised if it cracked a minute. The more I fly in rubber contests, the more I'm getting convinced that prop design and motor selection can count MORE than airplane design. Weight isn't as critical as you might think either- I've seen a relatively heavy T-6 hit 50 seconds versus a lightweight one break 56 sec. The lightest weight one hit 30 sec at a contest-and we were all using the same prop. Difference was weight of the airplane, building technique, and what I think was most important- rubber. Hence in these little FF conversions, I think that the prop selection is very important- and possibly more so than total watts.

At the rpm we're turning, I think the GWS blade design may be more efficient than a stock rubber prop which is intended for much lower rpm. I wouldn't worry about blade flex- we're not anywhere near the 25 watts or so where that might enter the picture. I haven't had great luck using rubber props in geared electrics- on my Lancer they seemed to not climb well. I'm guessing that there is too much blade area- and at 5-6k rpm we're way beyond rubber which I think is 1-2k rpm. The added blade area just turns into drag rather than useful power- and I'm not certain that most rubber props don't suffer from the same problem In other words, rubber props should start looking like the APC E props we're flying- and the APC slow fly prop should really have similar blade shapes as the E prop- and people might need to go to larger diameters instead of the added blade area. Think Gary Wright had this idea a couple of years ago-. Problem with using e props in place of SF props is that often the E prop is too heavy.

Suggestion- try a 5" GWS prop - see what happens to the amp draw and rpm with your current motor gearbox. If the amp draw and rpm is similar to my setup, we'll know it's not the gearbox. I'll bet though that your rpm is lower and amp draw higher.

Sam

[jrb]

Sam,

You’re absolutely right; the prop is where the “rubber meets the road”.

Me of all folks ought to be thinking more about the prop in this application; as I’m one of the guys who suggest that E needs less (than glow) watts to fly better.

Kind of like putting most of you money into the speakers.

Tell me which pitch and I’ll pick up a GWS on the way home and report back when I can. The micro GB/motor are a bit noisy; but they mount up easy.

Have you tried any of the Road Kill stuff ( http://www.djaerotech.com/dj_product/accessories.html#mps-1a )? They’ve gone from Gunther to GWS.

Jim

[Megowcoupe]

Hi Jim

I checked out the DJ aerotech web site- got some ideas. I suspect that if I wanted to start fresh- going with one of their units wouldn't be a bad idea- not much more money and probably less aggravation than an LPS. I'm keeping that in the back of my head for next time. I'm not surprised that they went with a GWS prop- they're a lot lighter, and I have a hunch they have a better blade shape than the Gunther. I don't know what the Gunther does though- I think those props are actually better than you'd guess by looking at them. I've seen pretty surprising performance out of them- especially the 5 1/4".

In terms of pitch- heck the GWS stuff is cheap enough- why not buy both (think it's a 3" and 4.3" pitch option on a 5" prop? And besides you lucky dog- you have an LHS that stocks that stuff on the way home from work. The LHS around here that I frequent doesn't, and the one I won't go to probably does.

You've got to go to gear on the 'String- it'd be sacrilege without.

Sam

[jrb]

Sam,

Actually two via one route and another two via another – though the 2nd don’t have much and are sister stores. Also, a couple more around; been told we have too many in town(s).

Will gear the String; maybe after 1st flight, since I have easy access to that part of the fuselage.

Is your K new and not die-crushed?


Jim

[Megowcoupe]

Good grief no. Actually, I still have much of the printwood that came with the K- it was rock hard so I did the xerox trick and used lighter wood. The kit stuff I might use in spots like the nose formers or landing gear formers- high stress areas.

The last airplane I built using Comet stock wood was well, come to think of it a Clod Buster, but since that's mostly stick- doesn't much matter. I built it for outdoor use, and I wanted something that wouldn't thermal too easily- it fits the bill fine. The Comet Gull II was what I was originally thinking of- and that airplane really does have a weight problem with the stock wood. I got the kit partly started and just said to heck with it and built it using the kit wood- originally built for a HY-50B drive and Kokam 3 cell 560 pack. It flew OK, but not wonderfully- relatively quick and not all that maneuvrable. After a cold day lead to a dork- I said to heck with it, yanked the gear out, and have started trying to fly it rubber. Might be OK- at least it's not cartwheeling. Won't have great duration, but what I've discovered is that I don't fly high duration airplanes (Sparky, Gollywock, Jabberwock) unless I have a really big field- and I might fly something that won't drift so far where I fly RC. Plus, the heavy duty rubber stuff has too much setup- I'm not adverse to using hand winds or a simple stooge.

Sam

[jrb]

Got the props and did a quick test series as shown below, interesting data.

Used my 101 a big Whattmeter and long wire going from Sermos to Dean to JST; a bit of loss.

Didn’t measure rpm or thrust; but something a bit more interesting: E is the velocity (mph) off the back of the prop via a Kestral 1000.

T is thrust calculated from E and D, diameter.

Wp is T*E; propulsive/propeller power.


Looks to like the 5x3 is the best choice; the Dare the worst. The Dare also has a throaty sound; the 5x3 smooth.


You might find this interesting, I performed a similar analysis on my Mustang with the prop I fly and a 2 blader that loaded the system exactly the same (read as 101 reads the same); an equivalent 2 to the 4. The 2 blader was a 16x10 and can’t be flown on Short-Fuse Salle; 12.5 is about the largest – the 4 was 15x11 but has been trimmed to 12.5.

The 4 made more E and its was T is also larger! Wp for the 4 was also better.

The Mustang has been clocked at 73mph, pitch speed calculates to just under 60; while I measured just under 40!

[Megowcoupe]

Hi Jim

Well, in the absence of tach numbers- it's very tough to figure out the relative efficiencies of gearboxes. However, your measuring scheme -neat one- put a velocity meter in the airblast- although I wonder how big a function is exact placement on your readings? I suspect this may be at least as accurate as the Thrust O Meters which abound (and to which I pay absolutely no attention unless I want to try to get something to hover.) Might be more useful in EDF though where raw thrust numbers don't tell you anything about how fast the airplane is going to go.

Based on your numbers- my offhand guess that a GWS 5 x 3 looks to be a good match seems to be confirmed- although what you'd really want is probably a touch more diameter and pitch (to get the A draw up a bit more.) I wonder what tweaks the DJ guys are doing to the 5 x 4.3 props? If they're thinning the chord near the tip, that might help. (or are they just balancing the dratted things?) However, we both know that the real test is when the airplane is airborne-both of us have seen props that look great on the bench do lousy in the air and vice versa. If I can't get my Airknocker off the drink with the 5 x 3, I'll kick around a different prop, but at this point, I'm pretty happy with how it flies.

Sam

[jrb]

I’ll grab the tach this weekend Sam and, do the 5x3, also repeating the E.

Won’t be measuring thrust, my thrust measuring system works more in pounds rather than oz; E, Tm (measured) & Tc (calculated like above), along rpm and *Calc predictions were in very good agreement during my Mustang test and other prop test.

Have a great weekend!

Jim

[jrb]

Got the tach out, measured 5580rpm with the 5x3; other parameters were the same.

How’s that compare to your data Sam?

Looking at the GWS data for the LPS “B” looks like the 6x3 might able to run on the Kok145?

FYI DJAerotech GB is 4.2:1 and do 6W with the 5043; they didn’t share any other data.

[Megowcoupe]

Hi Jim

I think you're confirming that the Aeromicro box is problematic. I just rechecked my setup- saw between 6200-6300 rpm on the GWS 5 x 3. I'm using a TNC tach by the way- not a lot of digits, but supposedly rather accurate. If our amp draw is comparable at around .4A and we're using the same batteries Kokam 145s- then the Aeromicro box is down a couple of hundred rpm- not good. Other possible sources of measurement error are whattmeters- I'm using the little whattmeter for my measurements, along with the JST connectors (well, at this low draw, they should be fine.) If needed, I can change the prop and go to the 5 x 4.3- think I have one handy and see what comes of it. It's also possible that the motors have a different wind, or just a lot of variability.

Another possibility- I remember that replacing motors in this little gearbox wasn't the easiest thing to do- I think I rotated the motor in the box before taping it up to see where it sounded healthiest. If you have access, you might try giving the motor in the box a little tweak to see if your rpms pick up.

Sam

[jrb]

W/o Whattmeter, esc, etc., I picked up 60rpm.

The Aeromicro box may not be of the highest quality, and probably looses a bit with its 2 little planetary gears; but it sure is nice to fit into the nose of the ShoeString.

It is a little noisy which is a good indication of loss; but seem OK.

I did push my motor a bit when I 1st ran it; put a 6” rubber prop on it; so it might be tired.

Also, its an MPI who knows how similar it might be to the GWS??

Since the Aeromicro can use the IPS motor there is no flat on the box and the motor can be rotated to any position.

Might pickup a B if I find one at the LHS.

[Megowcoupe]

Hi Jim

I hate to say this, but you may be in rethink time. Let me throw out a couple of ideas and what I'm basing it on-

1) Yes, I know the Aeromicro box is theoretically cylindrical as is the motor case. Nevertheless, when I tried dropping a new motor in, rotating the can did seem to matter- YMMV.

2) I think the 'String is going to be terribly undergunned on this box/motor/prop combo. My data points- 2 relevant airplanes- Guillow's Lancer and abovementioned K.
Flight trials with the Guillow's Lancer- used the Aeromicro box (HY-50K) similar size motor to the LPS- sounds like similar watts as well. Tried with 4" GWS prop- got a powered glide at around 5 input watts IIRC. This was using the Kokam 145s. Tried various rubber props- all without success- at best a powered glide. Also dorked the gearbox several times-0 @$%@%$&*&* Guillow's had a wicked nosedive with the cg in the correct spot- eventually added enough positive incidence to the wing to fix it. Eventually I trimmed the nose back, went to an HY-50F which is a larger motor (might be similar in size to an IPS) which now necessitated 2 cell Etech 250s. I did get the airplane to fly- but it was very marginal. Hard to get it to climb, and really not all that pleasant- came down quite determinedly when the power was cut. I concluded that the wing loading was too stiff for the airplane- yanked the electronics out- put in some extra structure- and went back to rubber. Gave it to some friends of mine to hang in their son's room.

3) Guillow's Lancer and Aeronca K have similar wing areas. Weight of the Lancer was probably comparable to the K- heck, I got the Lancer to fly nicely on rubber (think I used a 6" prop) which is more than I ever did with the K. Used the same servos, electronics and battery in both airplanes. May have been the same motor- certainly comparable in weight. One airplane flew (GWS B box and 5 x 3 GWS prop)- the other airplane didn't- Aeromicro box 4" GWS prop. By the time I got the Lancer to fly with the Aeromicro box- needed a fatter motor and batteries.
4) I've had good success with the Aeromicro box in 12-15 watt systems. I'm not saying the box is junk- but it does have a fair amount of drag comparated to the GWS and probably the DJ Aerotech stuff. I have a hunch that you're throwing away a watt or two- which kills you at the 4-5 watt level.
5) I think the 'String is going to need more oomph than the K. Since it's a solid sheet airplane, I'll lay long odds its heavier. The K does not have a lot of power reserve, although apparently the B drive can swing a larger prop. But if it can only swing a 6 x 3- that's a problem- you won't have the pitch speed you're gonna need. Why not call DJ aerotech and ask what they've got that will swing a 5 x 4.3" prop with a bit more oomph. What about a 3 cell approach- go to around 7 watts? Might need the C gearing. I guess the other option is the same one I did- fatter motor and fatter cells. Lancer's wing area (and the K's) is around 75 squares. I'm actually getting so frustrated, I may start designing an airplane around this system (HY-50F and 2 cell Etech 250) that will have a 24" wingspan (want it to fit into a box for travel.) Gonna need closer to 125 squares though- so I'm looking for a low aspect ratio wing.

Sam

[jrb]

Sam,

Thanks once again for your input!

I hate mucking up your K thread so I going to post an update to the following N20/IPS thread and hope you can post more thought there are well: http://www.rcgroups.com/forums/showthread.php?t=291938 .

Another data point I thought of, but don’t have it with me, is the Scratch-65 article by Bob Aberle in the Feb MA (w/help from Tom Hunt).

IIRC, they use the Micro Joule system (like me), Kok145, and a LPS; but I don’t recall which LPS.


Jim

[Megowcoupe]

Well, one more data point-

I took the K outside today, with a remarkable lack of success. Don't know if it was the outside air temps which were around 40 F or so. I tried ROS (rise off snow) several times. The airplane got airborne without too much strain, but really didn't have enough pizzazz to get out of ground effect. Any time I tried to climb- stall followed by a plop to the snow. I think I'm going to try the 5 x 4.3 prop next- if it's too much oomph- that's what a throttle is for. I also don't recommend snow as a takeoff surface for tissue covered floats- D'OH!.

Sam

[jrb]

Sam,

Once again many thanks for your thoughts.

Here’s a photo of the Scratch-65: 30”, 110sq”, 2.6oz RTF, LPC=B2C-C (6.2:1), GWS 6x5 (reduction, not HD/direct), w/2S-145 – 0.6A, 7V, 5W, 4200rpm.

BOL w/the K!


Jim

[jrb]

Sam, were your LiPos a little cold?

Flew my A-10 once @ 50F w/o thinking about the pack being “chilled”; would climb worth a darn, guys thought I was lucky to get back onto the runway.

A 2nd flight no long after was like normal when ambient temp was greater than 70.

Now I always warm my LiPos on the dash (windows open) if its cool; even on a summer’s morn.

Also, I think you need more prop; use the at least a 6, chart say you could do a 7x3.5 w/throttle management.


BOL,


Jim

[Megowcoupe]

Hi Jim

Good thought- but I think with the smaller packs- it doesn't much matter what you do beforehand. By the time I tape up the hatch and trudge out to the field, I'll bet the temps on the little buggers was dropping. However, even indoors at reasonable temps- there really wasn't a lot of power reserve. I have a hunch the 5 x 4.3 prop is the ticket- which is probably why the Aerotech guys also picked it.

I don't believe GWS charts- a 7 x 3.5 is going to pull more amps than I think the batteries can handle (don't know about the motor) and besides- I'm not sure this airplane had adequate pitch speed on a 5 x3 prop at 6200 rpm. Going to lower rpm is just going to make the matter worse- plus on the Aeronca, I don't think there is clearance for a 7" prop- never mind the torque effects.

Sam

[CA'ed fingers]

Hi Sam, any developments? Have you tried her off water? I want a micro that lands on water for the summer and I'm trying to decide on models and power systems as you already know from my SE5 thread...
eric

[Megowcoupe]

Hi Eric

Nope, haven't even done a float test yet. I don't get to fly off water all that often, so I haven't been in much of a rush. Bear in mind that a micro is going to need a very small body of water-I found that a NJ lake which was pretty calm, still had enough chop to cause some issues for a Pondscum. However, if I were doing this airplane again- I'd go to the DJ Aerotech motor setup- it's a touch lighter and has more oomph.

Sam

[Megowcoupe]

Hi Eric

I didn't get a chance to fly the Aeronca this weekend (left the rx home- "D'OH!) but I've pool tested it. Simply put, not very promising- the airplane does not have a lot of reserve buoyancy, so the floats are in pretty deep. I've run it the length of a 10 m pool, and it shows no signs of wanting to become unstuck. I have a hunch a micro that can carry floats and get off the water is going to take some good design and lots of power. The best setup I know for getting off the water easily is a seaplane- i.e Pondscum- with wing mounted twin motors- none of this pylon nonsense. This minimizes the tendency to play U-boat.

Sam

[Megowcoupe]

It's been awhile since I updated this thread. Flying the K in the summer proved to be fine. I even got in a little water flying- handlaunch off a dock- when you land- taxi back. Flying on the Hudson meant that some of the swells were pretty large in comparison to the airplane. The airplane doesn't need a water rudder- does fine with airblast and the flying rudder. The airplane isn't hard to fly- but it does have a tip stall issue, which makes it a bit more than a rank novice should tackle. It really does best as a free flight- just lazy circles, minimal control inputs. Not enough power for aerobatics. I'm saving mine for flying off water- the tissue covered floats don't do so hot when used on land- I keep getting rips in the tissue which doesn't help the flotation issue. Plus, it really does a pretty water landing with a little finesse.

If you must make the airplane unstick from water- my recommendation would be the Astro Firefly motor. It's a lot more watts- well a lot more rpm- for not a lot more weight. From my perspective, if I lose a GWS motor- I'm less likely to cry than if I lose the Astro- and let's face it- flying off water could easily lead to submerged components.

Sam

[Pat Daily]

Sam

I know it takes a lot more power to get the little guys off of water--this is really an issue with rubber powered scale free flight planes. I was having a similar problem even with the GWS planes until I increased the battery pack cell count. You might try 3 small lithiums versus two.

Pat

[Megowcoupe]

Hi Pat

I can believe it. I have a sneaking suspicion that surface adhesion/tension plays a much larger role in the smaller sizes than it does when you get larger. I could kick around adding a cell- on the li-polys, it's probably not as catastrophic as with nicads. Have to drop down in prop size though- I think the motor would zorch in short order and that gets annoying. Don't know how they did it with rubber- I guess they must have had one heck of a zoom once the airplane got unstuck.

Sam

[planeman]

I have built two Comet Aeronca K's on floats and both flew well on rubber. I might try it again using micro RC.

One word of experience with very small planes taking off on water. At the scale of the Aeronca the water is going to be like taking off in Karo syrup for the little plane. A lot of the problem is the water surface tension. I haven't tried it, but I read in the Waterplanes section of smearing Rain-X on the floats and hull to break the surface tension. A little soap might also work. What will work is gobs of power, probably more than you have in it now. My guess is you won't be able to take off on water, but its worth a try.

Anyway, that's my two cents worth.

Planeman

[Megowcoupe]

Thanks for the thoughts, but I may do this right one of these days- Astro Firefly and the Dumas S-6B.

Sam