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Author Topic: Crosby CR-4 NoCal  (Read 674 times)
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AAdamisin
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« on: March 08, 2020, 08:40:47 PM »

After finishing the Hawker Typhoon and Tempest,  I found out the the Cloudbusters were going to have a Thompson/Greeves NoCal mass launch event at the next monthly event as well as the Spring Fling in May.  So what is a guy to do??  Got to build another airplane.

I went through the FAC approved list of models.  I settled on the Crosby CR-4.  I found a nice set of 3-views and pictures and away we went.

I drew up the model in Draft site and it scaled to 16in span and 21.5 in long.  Holy smokes.  Really long!!!  It has 64 square inches of wing and the tail was already 20% of the wing area.  I set the wing incidence to positive 2 degrees, and the tail to negative 1/2 degree.  The motor tube is 15in long giving the hook to hook length 14in.   I designed a 1/2" thick airfoil section which is not thick for a 6.75" wing root.  I used 0.0325" x 0.070" lamination for the round outlines joining with the glue stick like I did for the Hawker models.  I used 0.0325" x 0.070" for fuse bracing, 0.0625 x 0.070" for the main supports, tail straights, and wing LE & TE.  Main center rib was 0.070" sq. and the rest of the ribs were stripped from 0.040" x 0.070".  I rolled the motor tube using a piece of 7lb 0.0325" x 0.875" x 15.25" balsa wrapped around a 0.260" carbon rod.  All balsa used was 7 to 8lb.

Art work was designed in Draft Site as well.  I pre-shrunk white gift wrap tissue with water, ironed it flat, and printed in my Epson 7710 inkjet printer.  Tissue was applied to the frame using an Elmer's glue stick.

Model was assembled with Sigment and thick CA.  Final weight is 6.57gr.  This is with the Dauntless prop.  Test glide was very nice and flat with no ballast needed.  Plan to use a 7" x 9.1"x 1" wide formed prop made in my 3D printed prop press. 

I will be flying it this Thursday 03-12-20 at the Ultimate Soccer Dome in Pontiac with the Cloudbusters.  Hoping to have a good showing.  Wish I had a practice site, but I should get it trimmed Thursday morning. 

Archie Adamisin
Burlington, KY               
Attached files Thumbnail(s):
Crosby CR-4 NoCal
Crosby CR-4 NoCal
Crosby CR-4 NoCal
Crosby CR-4 NoCal
Crosby CR-4 NoCal
Crosby CR-4 NoCal
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AAdamisin
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« Reply #1 on: March 08, 2020, 08:43:21 PM »

Here are some finished photos of the Crosby CR-4 NoCal.

If this flies, I will upload the files to the builder plan gallery with the 3D printed form STL's and tissue sheets.  Fuselage is in (2) pieces.  It is joined at the vertical behind the canopy. 

Archie Adamisin
Burlington, KY
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Re: Crosby CR-4 NoCal
Re: Crosby CR-4 NoCal
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LASTWOODSMAN
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REAL PLANES HAD ROUND ENGINES AND TWO WINGS



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« Reply #2 on: March 08, 2020, 08:56:44 PM »

     Hi Archie.  Your no-cal looks great.  I don't know much about no cal, so I have a question - what does the "business" side of the fuse look like?

LASTWOODSMAN
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OH, I HAVE SLIPPED THE SURLY BONDS OF EARTH ... UP, UP THE LONG DELIRIOUS BURNING BLUE ... SUNWARD I'VE CLIMBED AND JOINED THE TUMBLING MIRTH OF SUN-SPLIT CLOUDS ...
AAdamisin
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« Reply #3 on: March 08, 2020, 09:11:16 PM »

     Hi Archie.  Your no-cal looks great.  I don't know much about no cal, so I have a question - what does the "business" side of the fuse look like?

LASTWOODSMAN
Richard


Here is the buisness end. 

Archie Adamisin
Burlington, KY
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Re: Crosby CR-4 NoCal
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Indoorflyer
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« Reply #4 on: March 08, 2020, 11:10:12 PM »

You have some very nice NoCal designs. The outlines on the Crosby really look clean; the laminations around the spinner and cowl are especially nice.  Here's to a successful showing at your contest!
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OZPAF
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« Reply #5 on: March 09, 2020, 04:56:28 AM »

Like Indoor flyer I'm really impressed with the way you laminate the fuse including the spinner.

Good luck with them.

John

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« Reply #6 on: March 09, 2020, 06:46:57 AM »

"Minimum weight" requirements usually include the propeller, but not the rubber.
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AAdamisin
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« Reply #7 on: March 09, 2020, 07:26:46 AM »

"Minimum weight" requirements usually include the propeller, but not the rubber.

Cloudbusters require 6.2gram minimum weight and 7in max prop diameter for NoCal WW2 Mass Launch and for Thompson/Greeves/NAR Mass Launch.  There is no restriction on rubber.  

Archie Adamisin
Burlington, KY
« Last Edit: March 09, 2020, 08:39:29 AM by AAdamisin » Logged
Skymon
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fly it



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« Reply #8 on: March 09, 2020, 09:17:54 AM »

That's a beauty!
I'm tempted, as my No Cal Eindecker is a flop.
thanks for sharing
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AAdamisin
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« Reply #9 on: March 11, 2020, 07:00:26 AM »

That's a beauty!
I'm tempted, as my No Cal Eindecker is a flop.
thanks for sharing

Thanks.  Hoping for a good showing tomorrow in Pontiac.  Got 3 new Nocals to test and pick 2 for mass launch.

I'll get video.

Archie Adamisin
Burlington, KY
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AAdamisin
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« Reply #10 on: March 13, 2020, 06:50:04 PM »

Well, back the drawing board.  CR4 had some trim issues that I couldn't overcome.  Not enough decalage or dihedral didnt help.  Hunted in level flight and just couldn't find a happy medium.  Tried 3 different props, 6 different motor combos and it just didn't go.

Upon further review, It looks as if i set the stab at positive instead of negative incidence.  This long model is very sensitive to pitch.  So, back to the drawing board, but not giving up on it.  Didn't take any video, but I did accomplosh a cool rolling circle with it. 

Archie Adamisin
Burlington, KY
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« Reply #11 on: March 13, 2020, 07:50:35 PM »

That's too bad. Hope you can get it sorted.

Have you checked tail volume-CG calculations? The stab may need more area. Other possible remedies:
Add wash-in to the left side LE, if you're trying a left turn flight pattern.
Consider flying it in a right hand pattern.
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AAdamisin
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« Reply #12 on: March 13, 2020, 08:49:16 PM »

That's too bad. Hope you can get it sorted.

Have you checked tail volume-CG calculations? The stab may need more area. Other possible remedies:
Add wash-in to the left side LE, if you're trying a left turn flight pattern.
Consider flying it in a right hand pattern.

The current tail is 22% area of the wing.  The scale tail was 20% so I increased it slightly.  Going to scale it up again slightly maybe to 25%.  Going to make the next one with adjustable incidence tail.  Wing is set at positive 2 deg.  Dihedral is 1.25 under each tip.  FAC allows up to 1.33" on this span.  Going to the max on the next one.

Thanks,

Archie Adamisin
Burlington, KY 
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« Reply #13 on: March 13, 2020, 11:08:16 PM »

Having flown indoor nocal for many years, I can offer the following tips. Fly indoor nocal to the right, no matter what subject or weight. With no wing offset its too complicated to get them to go left. Easier to fly right. Incidence of 2 degrees pos in wing and -2 in stab is a good starting point. Might need a little more neg in tail but flight tests will confirm. Low wing design will need about 3/32" washout in the right wing tip and slightly more on left wing tip, about 1/8" total. Left tip must always have about 1/32" to 1/16" more washout than right tip. Offset back of fin around 1/8" for right rudder. You need at least 3 degrees of right thrust and about 2 degrees down thrust to start. You want a fly almost skidding right tuns and the differential washout and rubber torque will provide "left aileron" so to speak while right rudder is turning it to the right in a flat right turn. Add nose clay as needed to get it fly level laps with 4 degrees decelage. If not circling to the right nicely then increase right thrust some more, some models need like 5 degrees to pull the nose around.Also might need to add more rudder or kick the aft section of profile behind the rear hook to the right a little to help it circle right. Once you get a reasonable right circle and trimmed for level flight by adding nose ballast then add some torque and see what it does. If stalls and falls over to the left then add more down thrust, may need 5 degrees. If dives then needs more neg incidence in stab and cg more forward. Some models want more tip washout than others. Sometimes not enough washout makes them stall with power. Each nocal has its little idiosyncrasies some respond better with side thrust and down thrust for climb issues, others respond better with washout and rudder combo. You have to see what type it is. Most of my WWII nocals would get very grumpy if any of the washout in the tips was lost when stored in the box and flew best with more washout than less and as the weights got higher (6.2 compared to 2 grams) then they needed more down thrust and side thrust to control the climb.   
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AAdamisin
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« Reply #14 on: March 14, 2020, 11:15:14 AM »

Having flown indoor nocal for many years, I can offer the following tips. Fly indoor nocal to the right, no matter what subject or weight. With no wing offset its too complicated to get them to go left. Easier to fly right. Incidence of 2 degrees pos in wing and -2 in stab is a good starting point. Might need a little more neg in tail but flight tests will confirm. Low wing design will need about 3/32" washout in the right wing tip and slightly more on left wing tip, about 1/8" total. Left tip must always have about 1/32" to 1/16" more washout than right tip. Offset back of fin around 1/8" for right rudder. You need at least 3 degrees of right thrust and about 2 degrees down thrust to start. You want a fly almost skidding right tuns and the differential washout and rubber torque will provide "left aileron" so to speak while right rudder is turning it to the right in a flat right turn. Add nose clay as needed to get it fly level laps with 4 degrees decelage. If not circling to the right nicely then increase right thrust some more, some models need like 5 degrees to pull the nose around.Also might need to add more rudder or kick the aft section of profile behind the rear hook to the right a little to help it circle right. Once you get a reasonable right circle and trimmed for level flight by adding nose ballast then add some torque and see what it does. If stalls and falls over to the left then add more down thrust, may need 5 degrees. If dives then needs more neg incidence in stab and cg more forward. Some models want more tip washout than others. Sometimes not enough washout makes them stall with power. Each nocal has its little idiosyncrasies some respond better with side thrust and down thrust for climb issues, others respond better with washout and rudder combo. You have to see what type it is. Most of my WWII nocals would get very grumpy if any of the washout in the tips was lost when stored in the box and flew best with more washout than less and as the weights got higher (6.2 compared to 2 grams) then they needed more down thrust and side thrust to control the climb.   

Don,

Thanks so much for all the pointers.  After the Typhoon and Tempest flew so well, I was surprised that the CR4 was such a flop.  Very humbling to be honest.

The CR4 has quite a taper ratio so I am on board for the washout.  Is your recommendation based on a specific chord or a general use?  The CR4 has a 6.75" root and 2" tip.  I understand the decelage recommendation.  Its a bit more that I used on the Hawkers, but after flying the CR4, it was decelage deficient.

I will be building a new one with all of these adjustments.  Thanks again for all of your recommendations.

Archie Adamisin
Burlington, KY   
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« Reply #15 on: March 15, 2020, 03:34:08 PM »

I could never get any low wing indoor nocal to fly well unless it had wingtip washout. We use to fly WWII for many years locally so built IL2, Clipped wing Spitfire, Hawker Hurricane, P-39 probably more but key was washout on the low wings. Higher up the wing then the less washout needed until you get to a Fike. Never built a nocal with such a chord taper so that can be an interesting twist in the trimming process. If you decide to publish the plan and tissue files I may give this one a crack to see if I can get to fly. I like the challenge of a difficult or unusual subject Smiley 

Don     
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AAdamisin
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« Reply #16 on: March 15, 2020, 09:59:30 PM »

I could never get any low wing indoor nocal to fly well unless it had wingtip washout. We use to fly WWII for many years locally so built IL2, Clipped wing Spitfire, Hawker Hurricane, P-39 probably more but key was washout on the low wings. Higher up the wing then the less washout needed until you get to a Fike. Never built a nocal with such a chord taper so that can be an interesting twist in the trimming process. If you decide to publish the plan and tissue files I may give this one a crack to see if I can get to fly. I like the challenge of a difficult or unusual subject Smiley 

Don     

Don,

Thanks again for all the tips.  I have just uploaded the plans for the Crosby CR-4 NoCal.  I modified the plans to allow for negative 1 to negative 2 degrees of tail incidence.  I also increased the dihedral angle to 1.313" under each tip. 

I have yet to put washout in my WW2 nocals.  I have built the Typhoon, Tempest, and SBD-5 Dauntless.  All low wing and have plus 2 degrees incidence in the wing and negative 1 deg in the tail.  The tails are all 22-23% of the wing area.  All have flown to the left naturally with very little effort to make them do so.  I added about 2 deg of left thrust, a small dab of clay on the left tip to balance laterally, and that's it.  All (3) of my WW2 birds use a 7" x 9.1"x 1" wide wet formed prop using my 3D printed press.  My best time to date was 2:35 with the Dauntless.  The Typhoon flew 2:20 and no time on the Tempest as it liked to hang in the rafters.

Thanks,

Archie Adamisin
Burlington, KY   
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« Reply #17 on: March 16, 2020, 12:52:59 PM »

Looking forward to the CR4 plan getting added to the plans section. I have been meaning to get a new 11 x 17 printer. Last one was an EPSON WF-7720 and had the print head go out on me after 18 months. Bought the 3 year service plan so got my money back. Before that was an Epson WF-7710 that the print head died on. What printer are you using by chance? I liked the Epson due to Durabrite ink being waterproof but the print head issues have me hesitating on getting a new Epson.  I even had the second one setup to auto print a color pave every 7 days to keep the ink from drying out, still did not stop the head from dying. So was thinking of trying a Brother 11 x 17 but never tried their ink.
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« Reply #18 on: March 16, 2020, 01:46:37 PM »

Don,

I had a Brother 11x17 all-in-one printer before getting the Epson.  It printed beautifully, but the ink is very water-soluble and remains so even after multiple coats of dope.  Dew drops would blotch and smear sealed marking printed on both tissue and copy paper.  Might be ok for indoor models, but useless for outdoor.

Mike
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AAdamisin
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« Reply #19 on: March 16, 2020, 04:43:12 PM »

Looking forward to the CR4 plan getting added to the plans section. I have been meaning to get a new 11 x 17 printer. Last one was an EPSON WF-7720 and had the print head go out on me after 18 months. Bought the 3 year service plan so got my money back. Before that was an Epson WF-7710 that the print head died on. What printer are you using by chance? I liked the Epson due to Durabrite ink being waterproof but the print head issues have me hesitating on getting a new Epson.  I even had the second one setup to auto print a color pave every 7 days to keep the ink from drying out, still did not stop the head from dying. So was thinking of trying a Brother 11 x 17 but never tried their ink.

Don,

I have an Epson 7710.  I sure hope that the print head holds up.

I uploaded the plans last night.  It took the Typhoon and Tempest about 12 hours to post.  The Crosby is 4 Sheets so maybe that takes longer. 

Archie Adamisin
Burlington, KY
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« Reply #20 on: March 16, 2020, 09:06:26 PM »

Plans are there now and I have downloaded them. Thanks for making them available. What software do you use for the graphics? Just curious. I have been using ACAD then "hatch" all the colors etc. I like your 3D printed templates for molding outlines :-)   
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AAdamisin
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« Reply #21 on: March 16, 2020, 10:14:16 PM »

Plans are there now and I have downloaded them. Thanks for making them available. What software do you use for the graphics? Just curious. I have been using ACAD then "hatch" all the colors etc. I like your 3D printed templates for molding outlines :-)   

Don,

I use Draft Site Professional to draw the plans and do the artwork. 

I have the STLs if you'd like to print the forms and rib templates.

Archie Adamisin
Burlington, KY
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« Reply #22 on: March 23, 2020, 08:37:22 PM »

Any chance of posting a new set of printed tissue patterns for 8 1/2 x 14 paper. Not going to buy a new 11 x 17 printer at this time since Ohio is on "stay at home" mandate.

Don
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AAdamisin
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« Reply #23 on: March 28, 2020, 04:46:19 PM »

Any chance of posting a new set of printed tissue patterns for 8 1/2 x 14 paper. Not going to buy a new 11 x 17 printer at this time since Ohio is on "stay at home" mandate.

Don

Don,

Sent you PM.

Archie Adamisin
Burlington, KY
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« Reply #24 on: April 04, 2020, 08:08:23 PM »

Here are my covered parts, right at 3.0 grams so far. Thanks for the skin files.

Don
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Re: Crosby CR-4 NoCal
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