depron vs cellfoam88

airwolf2006 · Nov 02, 2009, 01:45 PM

Im thinking of building a Twirl from plans instead of buying a precut kit.I would use the standard electrics lightflite sells for it.Can cellfoam be used instead of depron?Ive read all the threads on this and cannot come to a concensus.What are the differences.I can get 3mm cellfoam locally but would have to send away for depron.Any opinions would be helpful.

KenSt · Nov 03, 2009, 12:35 PM

http://www.rcgroups.com/forums/showt...light=cellfoam

Do an advanced search for "cellfoam" in the title only. That's where I found this thread, there are others.

I'm building a twirl derivative from blue insulation foam, others have used Fan Fold.

airwolf2006 · Nov 03, 2009, 02:21 PM

Thanks Ken ,I had done that.I just had never read of anybody building an autogyro of cellfoam.It looks like it would work.Im just trying to save some money by building it myself and enjoy the build process.Ive never worked with foam but have the patience and dexterity skills to do so.If you have any helpful suggestions Id appreciate them.Id also like to know how your build goes.I guess Ill go pick up some cellfoam at my LHS.Thanks for your reply.

KenSt · Nov 04, 2009, 12:39 PM

I used bamboo skewers instead of carbon. In my area the 12" ones were about 5/32 (probably 4mm) in diameter. I didn't want them that big so I ran them through drilled holes in sheet metal to shave them down to 1/8 dia. The ones that are 1/8 in my area weren't long enough

. The weight penalty for skewers over carbon tubing 3mmm OD. x 2mm Id. is 6.7 grams. Yes, I took the time to figure it out.

My wings are removable. I have a skewer at the leading adge and trailing edge of each wing. Another two skewers serve as struts and go from the fuse to each tip of the other skewers. A balsa plate fits vertical at the wing tip and is glued to the triangles formed by the struts and wing edges. This also anchors the rotor shaft. The leading edge of each rotor blade are skewered as well.

I've been using plain old Aleen's quick dry tacky glue. (craft stores) It works on foam to foam as well as foam to wood. For really critical joints I use polyurethane glue.

The color scheme will be that of the pre war trainers yellow and blue. The yellow parts are made from meat trays. This foam is a little heavier than depron but is pretty stiff. I have a hot wire table and sliced these down to 1/8 thick.

airwolf2006 · Nov 04, 2009, 01:27 PM

Love to see some pictures.Im still on the fence on wether to buy a complete kit or scratch build.I really would nt be saving but about 50 bucks after having to buy all the incidentals,hardware etc. if I scratch build.But I would have cellfoam left over to build and repair with. I have a TX and RX and batteries.I would like to do some of the stiffening mods.I read weight was a big factor.I plan to use orange and black or a dark yellow and black for visibility.Thanks for the glue tips.Keep me posted on your build.Ill make my final decision in about a week on kit or scratch build.We are not to far away from each other.Thanks again for your reply.

KenSt · Nov 05, 2009, 08:42 PM

It will take some time for pic's. I have a camera but haven't used it in some time and never used it with the computer or RC groups. This will give me an excuse to try to get it all to work

The batteries are on charge now, maybe tomorrow night I will try to post. I want to learn how to do it so stay tuned.

KenSt · Nov 07, 2009, 12:07 PM

Here's some pic's of what I'm doing. The body is just blue foam sliced to about 5/32 thick. My experiments showed this was about the same weight as depron.

airwolf2006 · Nov 07, 2009, 03:05 PM

Wow.Nice job!Do the support struts penetrate the reinforcement plates?Are your rotor masts carbon fiber?The support rods balsa?It appears as you have bearings on your rotors.I like the PT19 profile.Thanks for the pics.

KenSt · Nov 07, 2009, 04:36 PM

Yes, the struts go half way into the foam and meet in the center. I cut a hole in the bottom of the fuse inside of each doubler to see that they meet, and filled it with polyurethane after the struts were in place. The rotor masts are 1/8 dia. fiberglass rod. The bearings are 2.5mm so I turned the rod ends down on the lathe at work. I have access to our tool room since I am one of two tool designers. The shop is about 20 feet from my office. I work at Pittman, a small DC motor company, so materials like aluminum, fiberglass, and ball bearings are easy to come by.

The struts are shaved down bamboo skewers. $1.00 for a bag of 100

at the local grocery store.

airwolf2006 · Nov 09, 2009, 05:28 PM

Thanks Ken.Did you use the original twirl plans?I know you made a profile change but other than that are your dimensions the same?Your rudder and elev. look different.Youve got some good ideas.It should be pretty sturdy.What AUW are you shooting for?I saw some Aleenes glue in the dollar store.Gonna pick up a bottle tommorrow.Im also looking at some different foams but will probably do 3mm cellfoam88.

KenSt · Nov 10, 2009, 12:48 PM

Yes, I started with the twirl plans and put them on AutoCad. Then I just superimposed the PT-19 outlines over top and scaled each item (stab, fin and rudder) up or down until they had the same area as the twirl with the same distance from the cg. So overall everything is the same size as the twirl.

I'm shooting for about 7-1/2 oz. The frame as you see it here is 2.64 oz. My radio stuff weighs .81 oz. Motor and 2 cell battery (880ma) weighs 3.22 oz. 6.67 total. So, with paint and landing gear, I shouldn't be too far off.

Lots of guys are using other than depron so I can't see a problem with cellfoam88

Just saw a thread where a guy built a 200% twirl. It didn't look like 3mmm depron.

Dollar store Aleen's

Nov 02, 2009, 01:45 PM	#1
airwolf2006 Wish my coax could autorotate Join Date: Aug 2009 Location: Riverdale Md. Posts: 814	depron vs cellfoam88 Im thinking of building a Twirl from plans instead of buying a precut kit.I would use the standard electrics lightflite sells for it.Can cellfoam be used instead of depron?Ive read all the threads on this and cannot come to a concensus.What are the differences.I can get 3mm cellfoam locally but would have to send away for depron.Any opinions would be helpful. Last edited by airwolf2006; Nov 02, 2009 at 03:23 PM.

Nov 04, 2009, 12:39 PM	#4
KenSt Scratch builder Join Date: Apr 2004 Location: Telford, Pa., United States Posts: 985	I used bamboo skewers instead of carbon. In my area the 12" ones were about 5/32 (probably 4mm) in diameter. I didn't want them that big so I ran them through drilled holes in sheet metal to shave them down to 1/8 dia. The ones that are 1/8 in my area weren't long enough. The weight penalty for skewers over carbon tubing 3mmm OD. x 2mm Id. is 6.7 grams. Yes, I took the time to figure it out. My wings are removable. I have a skewer at the leading adge and trailing edge of each wing. Another two skewers serve as struts and go from the fuse to each tip of the other skewers. A balsa plate fits vertical at the wing tip and is glued to the triangles formed by the struts and wing edges. This also anchors the rotor shaft. The leading edge of each rotor blade are skewered as well. I've been using plain old Aleen's quick dry tacky glue. (craft stores) It works on foam to foam as well as foam to wood. For really critical joints I use polyurethane glue. The color scheme will be that of the pre war trainers yellow and blue. The yellow parts are made from meat trays. This foam is a little heavier than depron but is pretty stiff. I have a hot wire table and sliced these down to 1/8 thick.

Nov 07, 2009, 12:07 PM	#7
KenSt Scratch builder Join Date: Apr 2004 Location: Telford, Pa., United States Posts: 985	Twirl derivative Here's some pic's of what I'm doing. The body is just blue foam sliced to about 5/32 thick. My experiments showed this was about the same weight as depron. Attached Thumbnails No wings. 115.7 KB · Views: 26 PT 19 frofile. I prefer this over the original twirl outline. All angles, areas, and moments are preserved. 100.3 KB · Views: 15 Lower struts reinforcement. I chose to isolate them as opposed to the kit position. 69.7 KB · Views: 15 Detail of rotor mast support. The lower end of the mast is glued against the balsa plate and is against the front strut joint. 136.4 KB · Views: 14 Wings attached. 102.8 KB · Views: 19

Nov 07, 2009, 04:36 PM	#9
KenSt Scratch builder Join Date: Apr 2004 Location: Telford, Pa., United States Posts: 985	Yes, the struts go half way into the foam and meet in the center. I cut a hole in the bottom of the fuse inside of each doubler to see that they meet, and filled it with polyurethane after the struts were in place. The rotor masts are 1/8 dia. fiberglass rod. The bearings are 2.5mm so I turned the rod ends down on the lathe at work. I have access to our tool room since I am one of two tool designers. The shop is about 20 feet from my office. I work at Pittman, a small DC motor company, so materials like aluminum, fiberglass, and ball bearings are easy to come by. The struts are shaved down bamboo skewers. $1.00 for a bag of 100 at the local grocery store. Attached Thumbnails Alignment hole filled with glue. Plates are 1/64 ply to increase surface area. 59.2 KB · Views: 12

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Nov 03, 2009, 12:35 PM	#2
KenSt Scratch builder Join Date: Apr 2004 Location: Telford, Pa., United States Posts: 985	http://www.rcgroups.com/forums/showt...light=cellfoam Do an advanced search for "cellfoam" in the title only. That's where I found this thread, there are others. I'm building a twirl derivative from blue insulation foam, others have used Fan Fold.

Nov 03, 2009, 02:21 PM	#3
airwolf2006 Wish my coax could autorotate Join Date: Aug 2009 Location: Riverdale Md. Posts: 814	Thanks Ken ,I had done that.I just had never read of anybody building an autogyro of cellfoam.It looks like it would work.Im just trying to save some money by building it myself and enjoy the build process.Ive never worked with foam but have the patience and dexterity skills to do so.If you have any helpful suggestions Id appreciate them.Id also like to know how your build goes.I guess Ill go pick up some cellfoam at my LHS.Thanks for your reply.

Nov 04, 2009, 01:27 PM	#5
airwolf2006 Wish my coax could autorotate Join Date: Aug 2009 Location: Riverdale Md. Posts: 814	Love to see some pictures.Im still on the fence on wether to buy a complete kit or scratch build.I really would nt be saving but about 50 bucks after having to buy all the incidentals,hardware etc. if I scratch build.But I would have cellfoam left over to build and repair with. I have a TX and RX and batteries.I would like to do some of the stiffening mods.I read weight was a big factor.I plan to use orange and black or a dark yellow and black for visibility.Thanks for the glue tips.Keep me posted on your build.Ill make my final decision in about a week on kit or scratch build.We are not to far away from each other.Thanks again for your reply.

Nov 05, 2009, 08:42 PM	#6
KenSt Scratch builder Join Date: Apr 2004 Location: Telford, Pa., United States Posts: 985	It will take some time for pic's. I have a camera but haven't used it in some time and never used it with the computer or RC groups. This will give me an excuse to try to get it all to work The batteries are on charge now, maybe tomorrow night I will try to post. I want to learn how to do it so stay tuned.

Nov 07, 2009, 03:05 PM	#8
airwolf2006 Wish my coax could autorotate Join Date: Aug 2009 Location: Riverdale Md. Posts: 814	Wow.Nice job!Do the support struts penetrate the reinforcement plates?Are your rotor masts carbon fiber?The support rods balsa?It appears as you have bearings on your rotors.I like the PT19 profile.Thanks for the pics.

Nov 09, 2009, 05:28 PM	#10
airwolf2006 Wish my coax could autorotate Join Date: Aug 2009 Location: Riverdale Md. Posts: 814	Thanks Ken.Did you use the original twirl plans?I know you made a profile change but other than that are your dimensions the same?Your rudder and elev. look different.Youve got some good ideas.It should be pretty sturdy.What AUW are you shooting for?I saw some Aleenes glue in the dollar store.Gonna pick up a bottle tommorrow.Im also looking at some different foams but will probably do 3mm cellfoam88.

Nov 10, 2009, 12:48 PM	#11
KenSt Scratch builder Join Date: Apr 2004 Location: Telford, Pa., United States Posts: 985	Yes, I started with the twirl plans and put them on AutoCad. Then I just superimposed the PT-19 outlines over top and scaled each item (stab, fin and rudder) up or down until they had the same area as the twirl with the same distance from the cg. So overall everything is the same size as the twirl. I'm shooting for about 7-1/2 oz. The frame as you see it here is 2.64 oz. My radio stuff weighs .81 oz. Motor and 2 cell battery (880ma) weighs 3.22 oz. 6.67 total. So, with paint and landing gear, I shouldn't be too far off. Lots of guys are using other than depron so I can't see a problem with cellfoam88 Just saw a thread where a guy built a 200% twirl. It didn't look like 3mmm depron. Dollar store Aleen's