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Old Jan 18, 2003, 10:04 PM
Registered User
Central NJ
Joined Mar 2001
708 Posts
Herr Stearman conversion - Ready for flight testing

Wow, now I know what they mean by this being the " building season ". It was 8 degrees - F this saturday morning ... no early saturday morning sneak-out for me this weekend !

This plane is alot of firsts for me.... first biplane, first rubber-band powered conversion kit,etc... I made many alterations to make this rubberband Herr kit the parkflyer I wanted..

Painstakingly stripped basswood stringers with an exacto knife ( there's GOT to be a better way to make basswood strips ! ). The basswood is alot stronger with not too much a weight penalty. Maybe for indoor flyers 100 % balsa construction is needed but Im thinking for the rough and tumble of the great outdoors alittle basswood added will be a big plus.

Both wings are removable , easy storage and transporting in small car with baby-seat , ha. Bottom wing is held on with magnets, top wing by rubberbands. At first I had the top wing on by magnets too but determined that the first dive would have ripped the top wing clean off , so it's rubberbands for the top wing now. Using magnets on the bottom wing is cool, holds pretty good and sure is alot less trouble then rubberbands.Covering is clear Doculam .

I liked the magnets so much that I made the cowl a removable cowl with magnets too. I wanted a removable cowl because I can plug and play a variety of motor systems in a couple of seconds. Im going to try the first flights with the GWS IPS - A and hybrid motors. My AUW will be about 9 ounces with the GWS IPS setups. I will take all my motors to the field with me and if I'm not satisfied with the performance of the GWS IPS with lithiums I can pop in the M-100 , the E-gull , the Johnson 250, or even plain ole 280 motors. Although trying to keep things light with light battery packs,I've made a dedicated hardpoint on the bottom of the fuse to accept aaa battery packs needed for the stronger motors if they become necessary. Hopefully I will have at least close to the success that other Ezoners have had using the GWS IPS motors with their Herr and Dumas conversions. I'll be flying this old biplane by rudder and elevator control.After seeing your Dumas Bearcat, Beaver,Herr AT-6, and Herr Corsair flying it gives me great hope that my plane will at least have some chance of flying...thanks for the inspiration !

If the plane proves to be flight-worthy I will paint it and do some cosmetic things to get it up to snuff, easier on the eyeball sort to speak.. even though there is a certain beauty of construction just seeing all of those wooden pieces, huh ?

Come on Springtime !!! Or at least some weather in the 40-50 degree range, sheesh, not 8 degrees ! What's up with dat ?
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Old Jan 18, 2003, 11:20 PM
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Martin Hunter's Avatar
Kamloops, BC, Canada
Joined Feb 2002
15,106 Posts
She looks great, but I need some closeup shots of your plug-n-play motor mounts you've got there please

Martin
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Old Jan 18, 2003, 11:31 PM
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central AZ
Joined May 2002
1,348 Posts
Is that a Saran wrap covering? I haven't seen a clear covering for a while now. But ever since I learned of Saran, it's always looked cool. Very interesting to have clear on there, though.

Nick
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Old Jan 19, 2003, 06:32 AM
Crazy Cessna Owner
Robbie d's Avatar
Australia, SA, Windsor Gardens
Joined May 2001
1,933 Posts
that is a great looking stearman, makes a change from all the tiger moths flying about. My girlfirend loves the look of the stearman but the cost of the kit seemed a little high, what's it worth these days?
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Old Jan 19, 2003, 09:31 AM
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Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
FF: My best warning is to make sure there is plenty of washout in those wings!

From the picture, it appears there's plenty in the top left, but the bottom left looks like it has some wash-in. I'd guess at about 1/4" at each tip should be good.
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Old Jan 19, 2003, 09:53 AM
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Central NJ
Joined Mar 2001
708 Posts
Hi Robbie

Yeah, you have to shop for prices on the Herr kits...The Stearman seems to be one of their more expensive kits..I've seen the Stearman between $40- $ 50 usual price but Christmas time was a good time to look for sales. A LHS had all their Herr kits for like $30.00 , no matter what model you chose, so I of course picked the Stearman , if this flies well I'll kick myself for not buying two, ha.

Knife- this covering is Doculam, a clear office laminating material with glue on one side. Nice and light, very strong and very cheap.Only downside to it is that it's tough to get wrinkles out, so you have to pull it as tight as you can while you apply it.You can then spray paint over it to add color. Ive got Solite also, Solite is prettier, you can easily have a no-wrinkle job with Solite but for me it tears too easy while applying, doesn't stand up to my hard landings , and doesn't add nearly as much strength to the frame as Doculam does. I guess every covering has it's ups and downs.Talking about Saran, I sometimes use Reynold's wrap covering, you can heat out the wrinkles just like Solite.

Hey Martin ! How's that Herr Ryan coming along ? You build alot faster and prettier then I do ... Ok, here's a pic of my plug and play system, I use it on all of my aircraft. I just build a light balsa platform to set my motors on and make a backplate with that strong 3 M velcro stuff. This " velcro " as Im sure you know, is much stronger then the normal clothing velcro we're all familiar with. My motors hold tight in place.... just build a strong firewall to hold a second piece of 3M velcro and you're set. This system also gives you a wonderful crash crumple-zone. With a strong firewall, when I crash, my motors just pop harmlessly off into the grass, rather then destroying my fuselage.I can also share motors between my different aircraft models very easy.. As you can tell by my photo this also allows me to be a mad scientist when it comes to trying different motors with my planes.... bwa-ha-ha

For the pic I have popped off my magnetic motor cowl so you can see the velcro and firewall.
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Old Jan 19, 2003, 10:11 AM
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robs's Avatar
United States, NY, Dutchess
Joined Jun 2002
652 Posts
FF,
Looks great. I love the plug and play motor mounts. Thanks for the pics, I will definitely have to store this idea in my memory banks for future projects. Would you mind taking a pick of the magnetic wing mounts? I'm curious how many you used and their placement to ensure that they hold.

Thanks in advance,
Rob
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Old Jan 19, 2003, 10:15 AM
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Central NJ
Joined Mar 2001
708 Posts
Hey Gene

Thanks for the heads up.. it must be something optical with the camera shot because it real life the wings are pretty straight and scale-like . But you're right, there's not too much washout in any of the wings , Herr didn't incorporate it into their plans,although I have to admit, their plans are pretty skimpy. . .It might be a good idea to bend in some washout though, thanks...Does the GWS TigerMoth have washout in the wings I wonder ? Also, for a rubber band kit I expected alittle more dihedral in the plans ( like the Earl Stahl planes have ) but this is the dihedral that Herr indicated in their plans. Good thing I built her strong and with a crashable front, huh ? I expect to have to make some adjustments.
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Old Jan 19, 2003, 10:33 AM
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Central NJ
Joined Mar 2001
708 Posts
HI Robs

Here's a pic of the magnets on my bottoem wing... just two magnets, one on the main spar and one on the traling edge. Seems to hold pretty good. Im not sure it would work for a top wing plane though, might have to get inventive for it to work on a top wing.
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Old Jan 19, 2003, 11:37 AM
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Levittown, PA
Joined Aug 2002
88 Posts
It's just as cold this side of the river. I'm thinking of having a Stearman of sorts. Magnet/wing idea sounds neat. Where is your LHS?

Bill
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Old Jan 19, 2003, 03:11 PM
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United States, NY, Dutchess
Joined Jun 2002
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Thanks FF,
That looks simple enough, even I might be able to pull that off. I was think of doing somthing like that for the SR Bantam Bipe I'm putting the finish touches on. Did you also mount magnets in the fuse, or just put some washers there? I have some magnets the same size and they definitely have a lot of holding power. Thanks for the inspiration.
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Old Jan 19, 2003, 04:00 PM
Registered User
Central NJ
Joined Mar 2001
708 Posts
Robs,

You know, originally I did try washers but they did not seem to hold well enough... so I also mounted magnets into the fuse .The magnet-to-magnet connection is alot stronger and better for holding something important on, like a wing . I did use washers on the cowl mount though. The magnet-to-washer connection is alittle lighter in weight and was strong enough for the removable cowl, which doesn't get alot of force put on it ( until a crash happens, ha )
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Old Jan 25, 2003, 04:35 PM
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Central NJ
Joined Mar 2001
708 Posts
Well, I got one short trial flight in with the Stearman this morning.
Winds up to 8 mph, alittle more then I wanted , but safe enough I guess. I now have plenty of washout in the wings and was ready for a trial run !

Seems like my Stearman,at 28 inch wingspan biplane wings, with basswood stringers,at over 9 ounces Im a tad heavy for the GWS IPS system with Qualcomm lithium batteries in sub-freezing temps. I gave her full thrust into the wind for a hand -toss, the wings had plenty of lift,maybe too much lift and drag for the GWS IPS to handle , she did not plummet to the ground, but rather tracked out slow and scale-like. She began an underpowered climb , banked to the right and fell in to the ground. She did this twice, the same exact pattern. I really couldn't try nimh batteries because the cold weather temps are making my nimh packs run very weak and sucky. Im definetely going to have to move up a notch in power system. I would have tried another power system on the spot but my servo connector came loose in my two crashes and I found that I had forgotten to bring my small screw drivers with my flight bag, so I had to take her home to re-tighten the servo control.

While disappointing, I learned alot with those two short tosses.

1. The GWs IPS is maybe not quite enough power for my basswood-strengthened 28 inch wingspan biplane Stearman.

2. Man, that basswood adds a ton of strength to the airframe ! My Stearman fell into the ground twice and didn't even blink... the only thing that happened was my Dubro Mini- EZ connector got loose and my pushrod became disabled. So it looks like the basswood has made her strong ebough for me to try a larger motor and aaa battery packs.

3. The magnets-connection idea on the bottom wing is fantastic !
On both of my crashes the right-hand tip of lower wing is the part that took the impact of the ground first. I also have a basswood leading edge on the wings. On both crashes the wing struck the ground, and then the wing popped harmlessly off into the grass... not a single scratch to the wing or fuse


4. I may have to back down from a 10 inch prop- too early to tell yet but since my plane fell to the right two times, I might have alittle prop torque pulling her to the right. Will have to experiment more to find out.

5. While watching her try to climb out today, even underpowered she looked like she is a stable airplane. I think that with a stronger motor that she will be a great plane to fly.

On my next trial run Im going to try an Egull motor and M-100.
Im going to have to try 8 cell aaa packs. While I think the Egull runs best at 7 cell nimh, this darn cold weather is making nimh flying very difficult, so my 8 cell nimh pack will barely have the power of a summertime 7 cell pack really. Anyone else experience this with nimh cells ??
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