Upscale Tasmanian Devil

[gpoehlein]

Has anyone upscaled the Taz to 24mm (D12) motor size? I've successfully upscaled it to 18mm and flown it on B motors, but I was wondering if anyone ever tried it on a D. I did find that, when flying with a B, you need to use a B6-0 or else risk the thing "ejecting" on the ground (not that it ejects the motor, but if you are flying in a NAR contest, the ejection charge can't go off after it hits the ground or you are DQed).

My upscale version (on the drawing board - haven't built it yet) has 5-1/2" BT-50 tube with a BNC-50 nose cone, and the rotors are 1-1/4" wide by 8" long. I figure to use 1/8" balsa.

 

[artapplewhite]

Snip... if you are flying in a NAR contest, the ejection charge can't go off after it hits the ground or you are DQed).
...Snip

I'm no Pink Book lawyer but I have flown in helicopter duration events at NAR meets. I'm not familiar with the provision of the United States Model Rocket Sporting Code you are referring to. Could you point me to the relevant Chapter and section.

Art Applewhite

 

[artapplewhite]

My upscale version (on the drawing board - haven't built it yet) has 5-1/2" BT-50 tube with a BNC-50 nose cone, and the rotors are 1-1/4" wide by 8" long. I figure to use 1/8" balsa.

It sounds like you're doubling all the linear dimensions. That approach seem sound.

I haven't built this rocket but it's the kind of rocket I like to fly. I do have a question about your upscale and in fact the original version. The drawing on the NAR web site is a "FULL SIZE DRAWING". How well do the approximately 3/4" wide rotor blades fit against the approximately 1/2" diameter BT-5 body tube of the original version? Is there clearance past the rotor blade for the launch rod to fit through the launch lug? Does it look like the picture when those dimesions are used? What are the dimensions of your 18mm upscale? Did you ever fly it on a "C" motor?

My curiosity has be aroused so now I'll have to build one and see. It would be interesting to change the rotor pitch and down slant and see what effect it has on flight duration. An increase in either would tend to reduce drag and thereby increase altitude but it would also increase the descent rate. The net effect may be nil. This sound like a good subject for a NARAM R&D entry.

Art Applewhite

 

[georgegassaway]

Has anyone upscaled the Taz to 24mm (D12) motor size? I've successfully upscaled it to 18mm and flown it on B motors, but I was wondering if anyone ever tried it on a D. I did find that, when flying with a B, you need to use a B6-0 or else risk the thing "ejecting" on the ground (not that it ejects the motor, but if you are flying in a NAR contest, the ejection charge can't go off after it hits the ground or you are DQed).

My upscale version (on the drawing board - haven't built it yet) has 5-1/2" BT-50 tube with a BNC-50 nose cone, and the rotors are 1-1/4" wide by 8" long. I figure to use 1/8" balsa.

Actually, the original Taz was built for 18mm.

For a 24mm version, on a D12, it needs to be STRONG. I think 1/8” balsa for the rotors may be a bit weak, they might flutter and flutter often means shred.

So, either 3/16” balsa blades, or VERY hard balsa, or maybe something else.

Also would be better structurally to make the chord a bit wider than 1.25", and shorten the span a bit. Since an intact model that does not shred is better than one that might fly 1-2 seconds longer, but ends up shredding.

Do not listen to Ryan who might tell you how to do vac-bagged foam core/fiberglass/graphite blades for a Taz, OK?

Also, plenty of good glue and reinforcement of the attachment joints from the blades to the rotor supports, and the supports to the body tube.

Fly it on a D12-0 and not say a D12-3, because the ejection charge of a D12 is VERY powerful and destructive (which would require a very large vent hole and adding stuff inside the BT-50 to keep the tube from roasting).

I’ll bet you are building this for a certain Indiana contest in 2.5 weeks?

Hopefully more for a “return” flight option than a “Flight Points” model.

You might therefore consider making a saucer type model with spin tabs. Some saucers can have tabs added. Or do a Tri-F-O which has spin tabs. You could make a “normal” sized Tri-F-O, using 1/8” balsa, and give it a 24mm mount instead of an 18mm mount. D12-0 for it, too.

Tri-F-O plans:
https://homepage.mac.com/georgegassaway/GRP/Plans/Sport/tri-f-o.htm

13mm Tasmanian Devil Plans (I know you must have them, but for those who are reading this who do not).
https://homepage.mac.com/georgegassaway/GRP/Plans/Sport/Taz.html

Photos below: Taz on left, Tri-F-O on right

- George Gassaway

 

[gpoehlein]

Actually, the original Taz was built for 18mm.

For a 24mm version, on a D12, it needs to be STRONG. I think 1/8” balsa for the rotors may be a bit weak, they might flutter and flutter often means shred.

So, either 3/16” balsa blades, or VERY hard balsa, or maybe something else.

Also would be better structurally to make the chord a bit wider than 1.25", and shorten the span a bit. Since an intact model that does not shred is better than one that might fly 1-2 seconds longer, but ends up shredding.

Do not listen to Ryan who might tell you how to do vac-bagged foam core/fiberglass/graphite blades for a Taz, OK?

Also, plenty of good glue and reinforcement of the attachment joints from the blades to the rotor supports, and the supports to the body tube.

Fly it on a D12-0 and not say a D12-3, because the ejection charge of a D12 is VERY powerful and destructive (which would require a very large vent hole and adding stuff inside the BT-50 to keep the tube from roasting).

I’ll bet you are building this for a certain Indiana contest in 2.5 weeks?

Hopefully more for a “return” flight option than a “Flight Points” model.

You might therefore consider making a saucer type model with spin tabs. Some saucers can have tabs added. Or do a Tri-F-O which has spin tabs. You could make a “normal” sized Tri-F-O, using 1/8” balsa, and give it a 24mm mount instead of an 18mm mount. D12-0 for it, too.

Tri-F-O plans:
https://homepage.mac.com/georgegassaway/GRP/Plans/Sport/tri-f-o.htm

13mm Tasmanian Devil Plans (I know you must have them, but for those who are reading this who do not).
https://homepage.mac.com/georgegassaway/GRP/Plans/Sport/Taz.html

Photos below: Taz on left, Tri-F-O on right

- George Gassaway

Thanks, George - I was hoping to hear from you about this. Yes, I'm wanting to build this as a backup return model for our regional contest this month. No worries about Ryan and his wonder resin - but I was thinking of coating the blades with CA and sanding them smooth to toughen them up. I'll go ahead and use 3/16" balsa then. After all, this is one of those "if it works it'll be great" kinda models!!!

I'll take a look at the Tri-F-O too - if nothing else it'll be a fun sport model!

 

[gpoehlein]

Finished and flew the 24mm Taz today. The rotors ended up being cut from 1/8" balsa (I didn't have anything thicker on hand). I ended up with the blades being 1-1/4" wide by 7" long. After shaping them, I wrapped Avery self adhesive label stock around each for extra strength. I used a plastic Alpha nose cone glued in place.

Flight today was with a D12-0 motor. It was a bit squirrelly as it left the rod (it was fairly breezy today) but it did fly and did not re-kit itself during the flight. Impact with a fence on landing dinged a rotor support, so I'll have to soak those with CA and clean them up a bit. I think it will do as a back-up model.