5.5" Cherokee-D L3 build thread for rharshberger

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rharshberger

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Today was the first day I have really had a chance to get to work on the build portion of my L3 project a 5.5" Loc airframe based upscale of the venerable Estes Cherokee-D (long version). Mainly today consisted of peeling glassine from the airframes in preparation to laminate and laminating each airframe section with two layers of 4oz fiberglass cloth and US Composites 635 3:1 resin. The rotisserie the tube in mounted on is a spare auger motor for my pellet stove and provides about 6rpm with the wooden gears I cut. Another project acually done a couple of days ago is starting the lamination of the avionics bay hatch cover.

Of course there is a gratuitous shot of the parts (including an extra airframe for another project). The glassine being peeled, the naked airframe, the hatch cover blank, the tube ready to start laminating, the stuff for laminating and the first airframe wrapped and rotating till the epoxy firms up. Naked tubes weighed in at 719 and 721grams each, the FG cloth adds another 122grams and the epoxy about 180grams, after tube has cured and peel ply removed I will get final weights.


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K'Tesh

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I Love the Cherokee D!
Are you going to keep the name and only change the D Power decal (like what I did for my 29mm version)? Or are you going to name it something like Cherokee M?
 

rharshberger

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I Love the Cherokee D!
Are you going to keep the name and only change the D Power decal (like what I did for my 29mm version)? Or are you going to name it something like Cherokee M?
True upscale, only the D-power decal will change.
 

kcobbva

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Very cool! Subscribed and looking forward to learning from your progress!
 

rharshberger

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Second airframe section is now laminated, no new pictures as they will be identical to the ones earlier in this thread. Also here is the updated OR file, its as close as the unbuilt rocket will allow and does not account for the FG lamination of the airframe.

View attachment Cherokee-M5.5LocSimforL3.ork
 

K'Tesh

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True upscale, only the D-power decal will change.
Good Choice! I always think it's weird when people build an upscale of the Cherokee D, then name it Cherokee M or something like that. If it could theoretically fly on an I or an O, then Cherokee M doesn't work... Changing the D-power decal to the motor diameter makes much more sense for them.
 

rharshberger

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Good Choice! I always think it's weird when people build an upscale of the Cherokee D, then name it Cherokee M or something like that. If it could theoretically fly on an I or an O, then Cherokee M doesn't work... Changing the D-power decal to the motor diameter makes much more sense for them.
Test flight will be on a L1000W DMS. I agree, as its a semi straight forward upscale other than a few design mods (DD, Zipper less fin can, nose Av-Bay). The exception for the motor lettering convention might be when I get around to building my 3" Arapahoe, I may call it a Arapahoe-G or something.
 

cherokeej

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Sweet. :wink:

Really nice rotisserie, BTW...
 
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patelldp

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Can you post a picture of the wooden gear? Maybe some insight on how you cut it (or a link to what you used as inspiration)?
 

rharshberger

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Can you post a picture of the wooden gear? Maybe some insight on how you cut it (or a link to what you used as inspiration)?
The only tools I used to cut them were a bandsaw, drill press, and a 1" combo belt sander. The drill press was used to make the bottoms of the gears (mine are rounded on the bottom of the V not square like the template generator shows), the bandsaw to cut the sides of the gears close to the lines, and the 1" belt sander to sneak up on the line. They would take much longer to make if each was cut on the scroll saw to perfection. Here is a link to the template generator, I just print out the gear templates and use a glue stick to attach to the piece of wood https://woodgears.ca/gear_cutting/template.html. The generator even allows you to set gear ratios by for example 14 teeth on one and 7 teeth on the other is a 2:1 increase or reduction depending on where the motor is located. I will add more pictures of the assembly later today.


Rotisserie1.jpgRotisserie2.jpg
 
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rharshberger

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Just peeled the tube this morning, definitely drier that I would like however it all seems to be the surface layer, only a few bubbles here and there to fix. I believe that the tube sucked up a bit more than expected. The original tube weight was 719 grams naked, the tube as it sits now is at 962grams. The fiberglass cloth weighed approximately 122grams (including an inch each end of overhang). Leaving about 121grams of epoxy, 1:1 on a cardboard tube is probably a little light, but the tube is still serviceable for the intended usage. The second tube should be much better as I used about 60grams more epoxy and the peel ply layer has a much better wet out than the first tube. The US Composite resin works well down to about 40F, but we also have low humidity here, I got zero amine blushing.


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TMR

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Subscribed. Looking good Rich!
I am loving all these build threads. You folks are Awesome!
 

pyrobob

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Very, very, cool man! Looking forward to following this.
 

rharshberger

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Today's update:

After removing my ghetto peel ply experiment I discovered that the peel ply material was wicking too much epoxy from the surface as is obvious from the earlier picture, that was an easy fix a Bondo squeegee/spreader and about 35 grams of epoxy. No big pockets to fill in on this one like my L2 bird from excess epoxy, I still managed to get a few wrinkles and bubbles but its not bad. Each airframe weighs in the neighborhood of 36-37ozs with glass. The hatch cover blank is about the right thickness now, and the Av-Bay bulkhead I vac bagged turned out okay, a little peeling of the surface by tough to remove experimental peel ply. 3 layers of FG each side of the bulkhead adds 41grams, I used the Bondo FG cloth which is easy to come by since I used the last of my 4oz on the airframes.

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rharshberger

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Got a bit more done today, just a few bulkheads, Centering rings and a few other parts.

Dry fitted the coupler to MMT for the zipperless , the various parts cut and prepped. The second picture contains all the parts cut today, the 4 CR's that make up the Motor section, the nose cone AvBay parts (3rd and 4th pictures are dry fits of that assembly). The nose Av-Bay uses a 14.25" section of 3" mailing tube as the area the electronics will be in, a short section of coupler will go on the bulkhead. Tomorrow will be drilling the nose CR and bulkhead for the screw and T-nuts that will secure the bulkhead to the CR, then epoxying the CR in place. Assembly of the fin can will have to wait until I can acquire the materials to make/buy the Y-harness (OneBadHawk will be doing the recovery harnesses, Teddy just doesn't know it yet). All the CR's are a perfect fit, the 4" IDs of the motor mount CR's are a bit snug, but after the glassine is peeled they should be perfect too! In the middle left of picture 2 is the lathe centers for the airframes so they can be power sanded on the woodworking lathe, as it makes the process much faster.




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Parts weights are as follows:
Nose Cone minus original base 512g
Nose Electronics bay centering ring 67g
Nose Bulkhead 54g
Electronics Bay Tube 102g

MMT coupler centering ring 1 43g
MMT centering ring 2 46g
MMT centering ring 3 46g
MMT centering ring 4 47g

All the MMT centering rings will loose a few more grams each after they are slotted for the fins, and or for the Y-harness.

Edit: The small holes in the centering rings are from the finish nails I use to temporarily tack the CRs to a waste board, so my hand and fingers are nowhere near the fly cutter type circle cutter in the drill press, the holes will be filled with epoxy durning the construction process.
 
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rharshberger

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Guess I do need to put out a thanks to my vendors so far:

Loc Precision for the nose cone, airframes, couplers and motor tube, and to Barry at Loc for the quick responses to my questions, and quick service.

Balsa Machining Service for the AT DMS L1000W for my eventual shakedown flight, and the AT M1297W reload for the cert flight, and to Bill and his wife, for their awesome and quick service.

Missleworks for the RRC3 Extreme that will be doing duty as the primary altimeter, I have flown this altimeter quite a few times and am totally comfortable with it and its reliability.

Eggtimer Rocketry for the Eggtimer Quark and Eggfinder TRS, the Quark is going to be the secondary altimeter, and the Eggfinder TRS in the nose for the tracking, thanks to Cris Erving for his awesome customer service.
 
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kcobbva

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Wow Rich. You do really nice work!
 

rharshberger

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Nose cone Av-Bay nearing completion, middle and middle right photos are after CR has been epoxied in place, the 3" tube will be glued in once the epoxy has had time to cure (probably tomorrow). The Nose cone bulkhead is held in by six 10-24 stainless pan head screws with two 1/8" brass pins for indexing. I still have 3 holes to drill in the bulkhead, one for the eyebolt, and two for the electronics sled mounting screws. So far everything looks good, the inner fillet has been done on the back of the CR.



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pyrobob

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Rich, excellent work and craftsmanship. Keep it up!
 

K'Tesh

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Looking Good!
 

rharshberger

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Got a bit more done today, just cutting the airframe pieces to size and rough sanding to prep for priming. Normally I would sand the entire airframe as one piece but Loc 5.38 airframes are 42" long about 6" longer than the distance between centers on my woodworking lathe. Definitely will need a bit of work to prime these for painting, most of the excess epoxy is sanded off, leaving very slight ripples, its not as bad as it looks, nothing several coats of filler primer won't cure.

Always remember to wear some form of respiratory protection when sanding FG or CF, I use a half mask APR and have a shop dust filtration system that keeps the flying dust to a minimum.


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Flyfalcons

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Awesome! I'm lining things up to make it to FITS and I'd love to see this one go!
 

rharshberger

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Anybody out there know of a better price on 5-6oz Carbon Fiber twill than Soller Composites? Soller seems to be about the best price I have found so far at $20.95 per yard, I need about 2 yards for my project still.
 

TMR

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US Composites has 5.7 oz / 3K CF @ 1yd x 42 plain weave for $16.50. I picked up a couple lengths of this and I like working with it. It works great on fins.
It is under the Discounted Carbon Fabrics section sixth item down.
 
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