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bfeist
Administrator
393 Posts |
 Posted - 30 Sep 2005 : 6:28:17 PM
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Finally decided:
I'm going to give a Curtiss R3C-2 a try. It's a beautiful plane and was piloted to victory by James Doolittle in 1925. http://www.geocities.com/CapeCanaveral/Lab/4515/r3c2.htm
[edited Oct 1]
Here are some additional fantastic detail shots:
http://www.airminded.net/r3c/r3c.html
I found a 1/6th scale short-kit with a 48" wing span (top wing) that reportedly has an all up weight (without fuel) of about 7.5 lbs. That would hopefully put it at about 8 - 8.5 lbs with electric equipment.
It'll be my first float plane (my previous was a trainer conversion to floats), my first bi-plane, my first outrunner brushless, my first big lipo purchase, and the first plane i've built myself in years. A tall order.
The seller of the short kit mentioned that A&J carries them, and that Jack is building one too.
As for the electric conversion I could use some help to figure out the motor config, although i'll buy the power system last. I was thinking of an AXI 4120/14 with a 4s3p lipo pack spinning a 14x9 (probably about 7200 rpm) which would produce ~500W (but at 40A). Feedback anyone? think this would do it? The AXI specs say this motor is for 6.5lb planes, but compares the performance to a 4-stroke 90 glow. I'm hesitant to go to 5s with a lower kV motor due to my charger only being able to handle 4s. I suppose I could break down and buy a new charger.
Lots of steps between here and completion. Any input/help/sanity is welcomed.
Benjamin Feist - EMFSO Site Developer |
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piker
Administrator
1150 Posts |
Posted - 30 Sep 2005 : 8:10:22 PM
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Ben,
Is that a local guy selling the kit? If so, I saw the plane at the Aurora Swap meet last spring. The model on display looked great.
It's bigger than what most others are building, but it'll be an impressive build. Your power thoughts seem reasonable so far, but you MAY want more power. However, with some careful lightening of the structure and the use of Li-po, you may be able to keep the weight down to even lighter than 7.5 lbs.
I would REALLY like to see the kit/plans when you get them. I'll try to help find places to shed some weight.
Robert
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Martin Irvine
Senior Member
26 Posts |
Posted - 01 Oct 2005 : 1:00:37 PM
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I'd like to see these plans too Ben. You know, you could do a photo reduction to 400 sq. in.....
I'm sure Robert can show you how to loose half the weight. It sounds heavy.
Martin
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piker
Administrator
1150 Posts |
Posted - 01 Oct 2005 : 1:56:10 PM
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My Libtery Sport had a 57" top wing and weighed 7.5 lbs with a geared AF40 on 20 cell. I don't think there was a lot more room for lightening. It didn't have two large floats on it either.
However, at 44" span, I think you may be right, Martin. With Li-po he may be able to get it down to 6.5 lbs..... or even lighter.
Ben, Why not share the link that you sent me?
Robert
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bfeist
Administrator
393 Posts |
Posted - 01 Oct 2005 : 2:45:08 PM
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Well, I bought the short kit at A&J's today. Looks fantastic. I bought a lot of the wood required as well from the parts list in the instructions. It looks like it uses pretty normal stuff:
Wings sheeted with 3/32 balsa
Fuse sheeted with 1/16 balsa
Floats sheeted on top with 1/16 balsa and sheeted on the bottom with 1/32 ply
Rudder servo in one of the floats etc.
There are a few strange items listed like a piece of 5/8" x 4" x 24" balsa used on the wings somewhere--maybe the piece that connects the top and bottom wing. I'll read through the instructions and take a closer look at the plans tonight.
I don't know how I could post the plans for everyone to see, they're huge. Maybe a digital picture of them--i'll give it a shot. The link to the short kit manufacturer that Robert was talking about is here: http://www.gdhconsulting.ca/page9.html
Benjamin Feist - EMFSO Site Developer |
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bfeist
Administrator
393 Posts |
Posted - 01 Oct 2005 : 5:44:59 PM
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I took some shots of the plans (not great) and a few pages of the instruction book. You can view them here: http://elconcho.dyndns.org/autoalbum/ShowThumbs.aspx?photodirName=2005-10-01%20-%20Curtiss%20R3C-2%20Plan%20photos
I read through the instructions--70 pages, 165 steps. My thoughts now are that it is a bit of a meaty construction. Lots of thick balsa and almost completely sheeted wings. One of the shots I took shows an image in the manual of the completed but still uncovered plane. You can see how substantial it is. It has strange things like 1/2" cap strips made from 3/32" balsa. The 5/8 x 4 x 24 piece is for the wingtips (sand to shape).
Does any of this strike anyone as unusual?
I'm looking at 25-28 oz/sq ft. according to the approx. 680 sq.in. the plans list. I calculated 725 sq.in. This puts it closer to 23-25 oz/sq ft.
I need about 600-700W i'm guessing. Anyone?
Benjamin Feist - EMFSO Site Developer |
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Martin Irvine
Senior Member
26 Posts |
Posted - 02 Oct 2005 : 5:32:15 PM
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With only 5 sq.ft. I'd be looking at 16-18oz./sq.ft.That means 5-5.7lb. To lose 2 lb. will mean a complete redesign. (Sorry!)
Martin
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bfeist
Administrator
393 Posts |
Posted - 03 Oct 2005 : 04:22:44 AM
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How can that make sense? This is a plan and kit that has been built before and is sold to come in at 7.5-8lbs. Has one never flown?
Benjamin Feist - EMFSO Website Developer |
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Martin Irvine
Senior Member
26 Posts |
Posted - 03 Oct 2005 : 09:07:14 AM
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Sorry, I didn't mean to imply that it hasn't been done. I'm sure that the prototype flew and probably one or two others before a kit would be even considered. I just meant that for pleasant, everyday flying, it will be a little hot at 7.5-8lb. It will certainly be flyable, but personally I would prefer a lighter wing loading. It would be easier to fly.
At 5.5lb, 400W would be sufficient and that could be obtained with a brushless Astro 05G
and a 3S pack. That would be a power system (IIRC)of just over 1 lb so with the radio, equipment could be 1.5 lb leaving 4 lb for the airframe. I'll bet that the airframe could be done for even less than that.
Just my 2 cents.
Martin
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Electroflyer
Veteran Member
75 Posts |
Posted - 03 Oct 2005 : 11:30:35 AM
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Ben,
I would suggest that you lose the sheeted fuselage and wings. Add stringers to the fuselage and Make a "D" tube wing(s) all covered with monokote or equivilant. When your airplane is complete, purchase your power system knowing what you then truly need.
Glenn
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bfeist
Administrator
393 Posts |
Posted - 03 Oct 2005 : 7:29:06 PM
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Sounds like a plan. I'm not worried about it being a hot plane (it is a racer after all), i was more worried that it might not be flyable.
Maybe I could get you and Rob to take a look at the plans and i'll throw away half of the wood i just bought (i'm an idiot).
Benjamin Feist - EMFSO Website Developer |
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piker
Administrator
1150 Posts |
Posted - 03 Oct 2005 : 8:13:56 PM
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Let me know which trash can you throw it in !!! 
Don't worry, you'll probably be able to use most of the wood. The rest can be used for your next project.
Let's plan a time on the weekend. Maybe Glenn and I can come over for a visit on Saturday, or something. You supply the beer.
Robert
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Martin Irvine
Senior Member
26 Posts |
Posted - 04 Oct 2005 : 12:44:22 PM
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Am I detecting a topical trend?
Martin
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gordonbw
Veteran Member
189 Posts |
Posted - 04 Oct 2005 : 1:43:37 PM
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I saw a completed GDH Consulting R3C-2 at the Heydenshore Pavilion show in Whitby the spring. That's SOME airplane... Ben, you are going to have your hands full this winter.
Gordon Braun-Woodbury
"How on earth do I land this thing?" |
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piker
Administrator
1150 Posts |
Posted - 04 Oct 2005 : 9:24:17 PM
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The beer topic? I think so.
quote:
Ben, you are going to have your hands full this winter
Ah, common.... you guys are freakin' Ben out!!!!
Don't worry Ben, you'll show 'em
Robert |
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bfeist
Administrator
393 Posts |
Posted - 05 Oct 2005 : 07:34:13 AM
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quote:
Ben, you are going to have your hands full this winter.
That's it, i give up :)
Benjamin Feist - EMFSO Website Developer |
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mistairjoe
New Member
6 Posts |
Posted - 05 Oct 2005 : 9:36:00 PM
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As far as i am concerned Ladie has the best beer,imported,Cech. hmmm how do you spell that, you know it use to and with Slovakia
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bfeist
Administrator
393 Posts |
Posted - 10 Oct 2005 : 09:57:00 AM
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Well, I'm making some half decent progress on the plane. Glenn Nikolaiko was gracious enough to go over the plans and short-kit parts with me and make some lightening suggestions (lots). As you've read above, if built as-is it would come out as a very heavy airplane. Glenn's hopeful that major modifications could take up to 1.5 lbs out of it--leaving me with an all-up weight of 6.5-7lbs.
Some of the main planned points:
Fuselage
- Discard 90% of laser cut fuse formers (boo). They're made out of very heavy 1/8" ply which is unnecessary for electric. I can use the ply ones as templates, and make 1/8" balsa sheeted with 1/64" ply formers.
- Change fuse to stringer construction rather than fully sheeting
- Modify firewall location to coincide with Axi 4130/16 location
- Completely redesign and rebuild the tail. Currently it's a thick 1/2" balsa construction sanded to contour. It also uses square structure pieces. I'll change these to triangle and will make it a 1/4" flat tail. The curve of the tail will be achieved by bending 1/32" balsa strips and laminating them together.
- Change top of rear fuse from sanded block of wood, to built-up construction.
- Create sloped battery tray through firewall.
Floats
- Partially sheet the floats (instead of full sheeting) if I can come up with a way to make them waterproof (Pike?).
- Drill lightening holes in float spines (it looks like swiss cheese now)
- Make floats removable and rig plane to accept gear of some sort (so i can fly it more than once a year)
Wings
- Partially sheet the wings (instead of full sheeting). Make them a D-Tube construction and use 1/4" cap strips everywhere.
- Revisit how the bottom wing is mounted (currently two 1/4" bolts). Might change this to a dowel off the LE and one bolt.
Benjamin Feist - EMFSO Website Developer |
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Martin Irvine
Senior Member
26 Posts |
Posted - 10 Oct 2005 : 11:12:49 AM
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Sorry you've had to do so much redesign but I think you are on the right track. I'd suggest you keep the fully sheeted floats. I'd think you would save very little by going to partial sheeting and they are going to be under quite a load when landing and taking off.
I really like the Curtis racers, and I'm glad someone chose to do one. (One of them was my #2 choice)
Martin
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bfeist
Administrator
393 Posts |
Posted - 26 Feb 2006 : 09:24:56 AM
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After a 3 month delay (stupid contract work) i'm back building this thing. I'm now officially worried that I won't finish in time. I'll be finished sheeting the floats tonight (took Martin's advice and went with fully sheeted 1/32" bottoms). Wings are next.
The manufacturer said that someone in the UK has electrified this kit. I'm going to try to get in touch with them to see what mods they made to do it and what power system was involved.
Benjamin Feist - EMFSO Website Developer |
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piker
Administrator
1150 Posts |
Posted - 27 Feb 2006 : 12:32:04 AM
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Hi Ben,
Glad to hear you're back at it.
I too have had a serious building delay. I've done very little since the first week of January. I plan to get back at it ASAP.
You still have 4 months. No excuses
Robert
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bfeist
Administrator
393 Posts |
Posted - 17 Apr 2006 : 12:44:29 AM
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Making good progress (thanks Pike!). Floats and both wings are finished contruction and now need sanding and covering. The fuselage is about half finished. I was planning on covering the fuse with monokote rather that 1/16" sheeting, but it looks like most of the strength is in the sheeting going to the tail, so i'll sheet the whole thing. The fuse is feeling a bit heavy...but i'm not used to building planes this big. it's probably just my own paranoia.
As for the power system, i've decided on:
Axi 4120/18 radial mounted
two 3s1p 3700mAh lipos for a total of 6s (20 cells equiv).
13x8 prop - should spin at around 9000rpm drawing 35A producing about 600W output.
These cells are very light. I got them from icare who provide very fast service and a resonable price (http://www.icare-rc.com/modelmotors_axi41.htm).
some modifications and deviations from the plans:
- sheeting with 1/16" balsa instead of 3/32"
- using 1/8" gear wire with rigging instead of 5/32"
- made mounting plates in the fuse for the gear wire to make the gear removable--mainly did this for portability reasons, but it also means i could potentially put undercarriage on the plane for non-float flying
- built up the wing tips by lamenating curved balsa instead of using blocks and sheeting
- modified the fuse to allow cowl removal all the way back to the leading edge of the top wing--mainly for easy battery access.
that's all for now
Benjamin Feist - EMFSO Website Developer |
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bfeist
Administrator
393 Posts |
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piker
Administrator
1150 Posts |
Posted - 24 Apr 2006 : 10:06:21 PM
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Great work, Ben.
That other photo....Is that full size? Looks like it.
Robert |
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bfeist
Administrator
393 Posts |
Posted - 25 Apr 2006 : 10:11:42 AM
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I think it is. it might be a later model. the markings are slightly different.
Benjamin Feist - EMFSO Website Developer |
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gordonbw
Veteran Member
189 Posts |
Posted - 27 Apr 2006 : 7:57:09 PM
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Wow, Ben! Beautiful work, and I can see you've made major progress since the EMFSO annual meeting.
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bfeist
Administrator
393 Posts |
Posted - 29 Apr 2006 : 08:55:44 AM
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Glen from GDH has contacted me and told me that the photo above is actually of a 3/4 model that was built a few years ago. Oh well, still beautiful.
Benjamin Feist - EMFSO Website Developer |
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bfeist
Administrator
393 Posts |
Posted - 31 May 2006 : 09:07:05 AM
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Painted the floats last night. They look awesome.
todo:
- put magnets into cowel for fastening
- sand and cover the fuse
- sand and cover wings
- bend the float strut wire again (and again) to get them symetrical and the right height.
- paint pilot
- get/make wing decals
- sand/cover wing struts
- mount electronics
- mount motor
- balance
- make battery tray
Benjamin Feist - EMFSO Website Developer |
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piker
Administrator
1150 Posts |
Posted - 31 May 2006 : 8:26:07 PM
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You can see the light at the end of the tunnel. Keep going. There's only three and a half weeks.
Robert |
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bfeist
Administrator
393 Posts |
Posted - 18 Jun 2006 : 03:19:07 AM
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Well, did a float test with Rob Pike this Saturday evening. It floats :) We taxied around for a while and practiced getting up on step. I'm drawing 39 amps static with 6s1p lipos (750W). The Axi 4120-18 purrs like a kitten.
Here are some shots (with a picture of the real Curtiss for reference). I still need to add the markings, pilot and some of the rigging.
Rob convinced me (of course) to try taxiing one last time and I managed to flip the plane over. The Jeti Advance 70 Opto literally exploded--spewing smoke and whatever that black crap that smells like money is that comes out of exploded Jetis. The guts of the plane are now coated in tar. My lipos are fine thank god. The plan is to get a Phoenix 60 this time instead of a Jeti--Rob assures me they are "more water resistant". Well, anything is better than exploding on contact with water.
A Dali painting?
Benjamin Feist - EMFSO Website Developer |
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piker
Administrator
1150 Posts |
Posted - 18 Jun 2006 : 11:49:13 AM
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Great looking pics.
Hey! It wasn't MY fault. It was the major cross wind that flipped you over.
Ben didn't mention that the reason he didn't test fly, besides the fast diminishing light, was that it was very windy. The water doesn't look too bad in the shots because it was an off-shore breeze.
Robert |
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Michael
Administrator
1320 Posts |
Posted - 18 Jun 2006 : 4:03:29 PM
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Sorry about the speed control, but the model looks fantastic.
The front shot looks amazing!
Michael |
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Rob
Veteran Member
154 Posts |
Posted - 18 Jun 2006 : 5:36:19 PM
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Yes, Ben. The model looks awesome!
Rob |
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Ken Wilton
Moderator
415 Posts |
Posted - 18 Jun 2006 : 10:06:54 PM
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Your plane looks great! Nice photo. Ouch for the ESC.
I'd suggest you get some "silicon conformal coating" for the next ESC. I coated my Hacker 40 with this stuff last season after having it's predecessor shoot flames 3" high after a brief splashdown. If I knew how to post pictures I'd show you the bottle (and the burn marks). It's less than $10 and it works . . . I know because I dunked my Cub on Saturday and once I got the water out of the wing I was back flying no problems at all.
Ken
ps I'll bring my bottle to Kingston in case you or others need some before the float fun. It only needs 30 minutes to cure. |
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bfeist
Administrator
393 Posts |
Posted - 18 Jun 2006 : 10:43:31 PM
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Thanks for the kudos. thank god i took some shots before the dunk :)
Ken, are you talking about this stuff?
Do you have to cut the label and shrink wrapping off the ESC before application? It sounds like just what the doctor ordered. I was planning on mounting the ESC near the trailing edge of the bottom wing where it doesn't get wet when upside down--but that would mean seriously long motor leads which might be a no no.
Benjamin Feist - EMFSO Website Developer |
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piker
Administrator
1150 Posts |
Posted - 19 Jun 2006 : 12:21:25 AM
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Hey Ben. I have a new can of that exact stuff sitting on my workbench. Why didn't you use some 
Ken, was your first, fried ESC a Jeti? Was your second, non-fried one a Castle?
Robert |
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Ken Wilton
Moderator
415 Posts |
Posted - 19 Jun 2006 : 09:47:17 AM
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Ben,
Looks like the same stuff except mine is either "paint it on" or dip the esc in. You do want to peel off the shrink wrap so you can get into all the nooks and crannies. I do two coats leing the first one dry before going over it a second time. I like to tag the power wires with some ID so I can tell what the power limit is for later on as I don't bother to re-wrap the ESC after coating but some people do.
Rob, Both are/were Hacker/Jeti 40's with BEC not opto. I know Castle does make a waterproof ESC but I've never tried one.
Ken
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rkhoo
Veteran Member
315 Posts |
Posted - 19 Jun 2006 : 10:51:21 AM
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Ben, great to see your beautiful work. Looking forward to see it.
Sorry to hear your burned ESC. You've mentioned "black-tar", that sounds like an explosion of an electolitic capacitor. These caps are design to explode (via the top trio-cut line) on failure, keeping the circuit open. You can verify this by looking at the top of the 2 caps on the right-side in your photo. There is a small chance the the ESC is still in good order. You may replace the caps and see if it work. Good luck.
Ben or Ken, where did you purchase the conformal coating? |
Edited by - rkhoo on 19 Jun 2006 10:54:04 AM |
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Electroflyer
Veteran Member
75 Posts |
Posted - 19 Jun 2006 : 6:41:42 PM
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Ben,
Outstanding! I am looking forward to seeing it at Kingston. Sorry to hear about the speed controller. E-mail Jeti, They stand by there products. By the way, I don't think it was the controllers fault, more like the ugly 'Pikers Curse"!
Glenn |
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piker
Administrator
1150 Posts |
Posted - 20 Jun 2006 : 12:27:10 AM
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| Hey! Who you callin' ugly? |
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Ken Wilton
Moderator
415 Posts |
Posted - 20 Jun 2006 : 09:02:06 AM
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Ronald,
Almost any electronics supply store would have the silicon conformal coating. I choose the silicon version because it could withstand a higher temp rating. It also seems to keep a little flexibility when it's dry as well.
Another good product is called "Corrosion X". It comes in a narrow can and you can get this at Pinnacle Hobbies or A&J's as well as Radio Control Hobbies on #7 Hwy. It costs around $10. This stuff is what I inject in my receivers to coat the PC board. It is designed to stop corrosion and keep electronics from shorting out even when wet. They used to run a demo of a TV that had been coated in this material, fully operational in the bottom of a pool! Some people open up their servo cases and coat the board and motor with the X.
I've not tried the corrosion X as the only protection for an ESC but I do give my ESC a small squirt of this stuff as a "just in case" after a dunking.
Ken |
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Topic |
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Ben Feist's Curtiss R3C-2
