1/4A Helicopter Duration

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gpoehlein

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One of the events our club chose for our first regional next spring is 1/4A Helicopter Duration. So I've been looking around in all my files and on the net - I cannot find a single model designed for that motor size! QCR had a 1/4A model, but they are currently shut down after the death of the owner and I have no idea if they will ever re-open. Fliskits does have an 1/8A HD model, but I'm not sure how well it can be modified for the larger motor. And that is it - I can find no other 1/4A design anywhere. Anyone know of any decent designs for this motor or have any thoughts about it? I'm afraid to even try it with a Tazmanian Devil because it will likely eject after landing, which will be a DQ in many clubs whether it actually spits the motor or not.

Granted, I've been doing this long enough that I know I can come up with something, but I'd rather not re-invent the wheel (so to speak) if I don't have to. And yes, I know that using a piston is pretty much a given here ;).
 
Greg,

My first choice would be Apogee's new Gyro Chaser, with a 13 mm motor mount set up for pistoning. With a 1/4 A and a good aerodynamic design, roughly a third to half the initial altitude should come from the piston. Fliskits Rose-A-Roc would be my second choice, again with a 13 mm mount instead of the 18 mm. The problem with the 1/8 A model is that, first, I don't think Jim is offering the Tiddlywink anymore. :( Second, I think even in dead air you are better off with the larger blades of either the Gyro Chaser or Rose-A-Roc.

Thermals,

Steve
 
Thanks for the reply, Steve. I looked at those, of course, but I was afraid the Rose-a-Roc might be too heavy for a 1/4A even with a piston. Pity about the Tiddly-wink - chad staging it with two micromaxx motors might actually be an option. As I was afraid, I will have to do some tinkering. Was just hoping that there might be a set of plans out there that I had missed.
 
The QCR kit I built and flew recently was a small section of BT-5 for the motor mount glued to a section of 10.5mm tube for the main body.
Blades were cut bent and glued instead of sanded to an airfoil, none of the plans on the NAR contest page show it, but it's a pretty easy way to get a good spin. Flown on the 1/4A3-3 without a piston, it was ejecting at apogee.

Looking at the plans on the NAR site, a scaled down rose-a-rock would be nice. Especially with a piston. Or replace the dowel and rotors with 10.5mm tube for something that looks like the QCR kit.

kj

HD IMG_7360.JPG
 
Build a 13mm Rotaroc, lightly (Peel tube if possible, use light balsa, don't dope it). See this link for a how-to-build page I added when I made up a few crude kits for some club members years ago.

https://georgesrockets.com/grp/CONTEST/Plans-C/Copter/CopterPlan/Rotaroc-A.html

Piston.

Enjoy.

Not NARAM-winning level of performance for 1/4A (unless you hit great lift) but pretty solid.

Say hi to Chad….

- George Gassaway

IMG_5366.JPG



Rotaroc_13mm_1.gif





Rotaroc_13mm_2.gif
 
Build a 13mm Rotaroc, lightly (Peel tube if possible, use light balsa, don't dope it). See this link for a how-to-build page I added when I made up a few crude kits for some club members years ago.

https://georgesrockets.com/grp/CONTEST/Plans-C/Copter/CopterPlan/Rotaroc-A.html

Piston.

Enjoy.

Not NARAM-winning level of performance for 1/4A (unless you hit great lift) but pretty solid.

Say hi to Chad….

- George Gassaway

Absolutely, George - Hope you guys are able to make it down to one of our regionals next spring! Didn't know if the rotaroc could be built light enough for 1/4A.
 
Absolutely, George - Hope you guys are able to make it down to one of our regionals next spring! Didn't know if the rotaroc could be built light enough for 1/4A.

George is absolutely Right! Been flying my 13mm rotaroc on 1/4A - A motors since the 1/4A 13mm motors came on the market.

Also designed a couple other 1/4A HD free Hub models over the years I really like this one. Building any of them... Light is KEY. Contest balsa and hollowing out NC helped on the Rota Roc.

041a1a1-sm_Rotaroc .25A-A 13mm  comp HD_02-01-90.jpg

041a1b_.25A-A 13mm HD Rotaroc (RotorsUp)_02-01-90_03-01-13.jpg

041b1a_.25A-A 13mm HD WonderWhirl (Rotorfins)_02-24-13.jpg

041b1b_.25A-A 13mm HD WonderWhirl (RotorfinsUp)_02-24-13.jpg

041b1c_.25A-A 13mm WonderWhirl T3 FreeHub Close_02-24-13.JPG

041b1d_.25A-A 13mm WonderWhirl T5 motor tube Close_02-24-13.JPG
 
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Absolutely, George - Hope you guys are able to make it down to one of our regionals next spring! Didn't know if the rotaroc could be built light enough for 1/4A.

Long ago when the 1/4A had a 2 sec delay, it was OK. Now, with the 3 sec delay, pretty much need to piston it or it'll be well on its way down at ejection

An alternative would be to make a "stubby" Rotaroc, shorten the body and blades by 4", for 8" long blades. Will boost a bit higher, but descent rate is faster, definitely not a good tradeoff for 1/2A or above.

- George
 
Long ago when the 1/4A had a 2 sec delay, it was OK. Now, with the 3 sec delay, pretty much need to piston it or it'll be well on its way down at ejection

An alternative would be to make a "stubby" Rotaroc, shorten the body and blades by 4", for 8" long blades. Will boost a bit higher, but descent rate is faster, definitely not a good tradeoff for 1/2A or above.

- George

For sure George:
At ECRM two years ago Glen Fev. flew away 2 modified Rota-rocs 13mm 1/4A HD models with 4- 1/2" x 8" rotors. I was surprised how well they rotated with 4 rotors.
 
For sure George:
At ECRM two years ago Glen Fev. flew away 2 modified Rota-rocs 13mm 1/4A HD models with 4- 1/2" x 8" rotors. I was surprised how well they rotated with 4 rotors.

Flying away two helicopters in a contest is one of the few ways I know of to become both ecstatic and suicidal at the same time. :y:
 
Flying away two helicopters in a contest is one of the few ways I know of to become both ecstatic and suicidal at the same time. :y:

Uh, yeah, unless it's multi-round and one flight got returned.

Or unless the contest has two copter events and you lose one per event (not great to lose models, but that often means winning the event. Last time I lost a copter model but did not win, the thing landed way up in a very tall tree, even the Launch Crue 50 foot pole, plus another 20 feet of poles taped to it, could not reach. 5 more feet to the left and it would have made it to the ground. Rule 10.4 applied for return technically, but we took 2nd because that was my top model and I did not have one that good for flight #2)

But for regular scoring, two flights total, return one or else, this is what POS* (but reliable) back-ups are for. I've often had two back-up types, one for sure return like a Tasmanian Devil or Tri-F-O. Some others, well, capable of a decent flight but if really windy I'm ready to tape (or even glue) spoilers to the top of the blades to kill the rotation rate so it does not perform very well.

Flying 1/2A Copter tomorrow. I have my top-level lightweight NARAM-level mini-Rotaroc, a thrown-together as club kit prototype for pics Rotaroc, a Tasmanian Devil, and a mini-gyro-disc copter. I do not plan to fly the top-level model, risking losing it, unless the competition puts up a really good score, will fly the thrown-together Rotaroc.

- George Gassaway

* POS = Piece Of SubParModeling (or something crappy like that)
 
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