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Old Sep 10, 2008, 11:25 PM
Team 30 Micro EDF
Mike Taylor's Avatar
Camarillo, California
Joined Apr 2002
4,516 Posts
Maybe you could plot your airfoil large enough to contain the radio, and just make the fuselage a lifting body. If you've got cross-section, you might as well use it...

That's a wicked looking wing. Good luck tomorrow!
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Old Sep 11, 2008, 06:30 AM
Registered User
Sydney, Australia
Joined Aug 2008
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Quote:
Originally Posted by Mike Taylor
Maybe you could plot your airfoil large enough to contain the radio

Yep, thats exactly what I was thinking of Mike for a second version, just a carbon boom for fuselage with small battery pod and the PZ Brick in the wing with some light fiber-glass skin around it, should be able to bury about 4.5 to 5mm in a 6.35mm thick wing.
That should be nearly enough as the entire brick is about 8mm over the horns.
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Old Sep 11, 2008, 11:32 AM
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micro_builder's Avatar
United States, TX, Fort Worth
Joined Jan 2005
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Thanks, Mike/Charos. I hadn't thought about sticking the RX in the wing and using the pod as a lifting body, but I like the sound of it. A new wing would indeed be needed, as even my bigger 19" wing is only about 6mm tall at the root, but something like the nose of an SR-71 comes to mind for the pod. Actually thats not a bad idea for a 30-40 inch DLG either.

Either way, she flys! Murphys Law is still out to get me, as the 50mah I burried in the pod was nearly dead (ok, that was my fault ), it rained all last night, and its not exactly calm outside right now, but I gave old Murphy a smile and chucked it anyway. It pretty much flew out of my hand, and went through the wind amazingly well, any of my other planes probably would've been thrown to the ground, but this one cut right through with ease. Finally, a windy day flyer! Its charging right now, and its supposed to clear up a bit later today so it'll get another go-round soon.

I whipped this one up last night mostly just to make use of the PZ rx and the smaller wing, but I'm glad I did it. If this one with all its drag flys this well, the 19" version, which should turn out lighter than this one, should work great. Now if only Kyosho would hurry up with their Cherokee, i could have ailerons too. I'll try to get some video or pictures today of some flying.

Nick
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Old Sep 11, 2008, 02:54 PM
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United States, TX, Fort Worth
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And now I know, don't smile at Murphy! Don't know what happened, but I just released the magic smoke from the PZ brick. *sigh*
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Old Oct 02, 2008, 07:45 PM
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United States, TX, Fort Worth
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This project is not dead, just been on hold. But, I got one step closer today with finally making a couple pod halves that actually look like pod halves (what a concept!). These are the 4th attempt at making a fuse pod, far from perfect, but far better than the first 3 tries.

I took the PZ RX out of the smaller glider to see what I fried on it, and it looks like the motor controller or the FET itself burnt out pretty badly on the elevator servo. Could still use it as a R/T system i think.

Nick
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Old Oct 05, 2008, 06:27 AM
explore!...
Kristian k's Avatar
Slovakia
Joined Jul 2008
199 Posts
would be nice if you would post a vid when youre done. I am close to taking the electronics out of my parkzone cessna because I crashed so many times trying to do stupid things that Im thinking of making a glider out of it.
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Old Oct 07, 2008, 04:59 PM
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United States, TX, Fort Worth
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Video for sure!

The airframe is now complete, and comes in at 10.8 grams. I figured a simple way to make swapping wings quick and easy, basically just plug in a wing and go. There's just enough room to run two CF push rods down the tail boom, keeping them out of the airflow, and the full flying elevator looks small, but its quite rigid. I put the hinge point a bit ahead of the elevators centerline, should make work for the servo a little easier. My AUW might just end up on the 16-17g range I was shooting for.

Still gotta get the PZ RX.

Nick
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Old Oct 07, 2008, 07:04 PM
TheyreComingToTakeMeAway!
derk's Avatar
USA, ID, Coeur D'Alene
Joined Dec 2003
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wow that looks awesome Nick! is that one also skinned with durobatics?
it looks just as if you shrunk a larger one down, great work.
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Old Oct 08, 2008, 06:42 AM
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Sydney, Australia
Joined Aug 2008
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Top work Nick

My version has not progressed further (Got sidetracked ).

Like you I am also using carbon push-rods inside the boom.

Nice looking fuse pod - the AUW of yours is way below what im targeting even if I do manage a MK2.
My MK2 would be about the 25-30g range.

Be shore to keep us all updated of your progress - Micro HLG is fascinating and challenging.
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Old Oct 08, 2008, 07:01 AM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
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Nick,
Very nice work. Your molded pod is excellent.

Gordon
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Old Oct 09, 2008, 09:49 AM
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Thanks guys.

Derrik, yep, this wing is skinned with durobatics as well. Its less than a half gram heavier than the tissue covered wing I did, and so far the entire plane weighs about 2 grams less than the first version with the balsa pod and tissue wing.

Charos, I think you'll be ok with a 25-30g range, Mikes 22" gliders had weights from the mid 30s to low 40s, and I think MITKid's little SAL was around 30g too. My AUW will climb when I go to a differant wing - I'm sanding out some solid foam ones today...heavy wind wings.

Thanks, Gordon. I've gotta give thanks to Graham Stabler for the pod, it was his Homebrew CF Props thread that gave me the basic idea of how to go about molding. I'll probably make a 2nd upper half of the pod, this one is just a hair too big on the bottom edge...not a great fit.

Nick
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Old Oct 09, 2008, 11:30 AM
Team 30 Micro EDF
Mike Taylor's Avatar
Camarillo, California
Joined Apr 2002
4,516 Posts
One observation on weight - the lighter of my two 22" gliders flies slower (lighter loading, undercambered wing) than the heavier one, but the heavier one can be thrown higher due to its greater momentum and near-same drag. Both have about the same dead-air duration.

Lighter is better for flying in low-lift, low-wind conditions. Most of what I do with them revolves around working slope lift over tree lines and local slopes, and it is nice to have a choice of a a high wind or low wind model.
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Old Oct 09, 2008, 05:20 PM
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Quote:
Originally Posted by Mike Taylor
One observation on weight .......but the heavier one can be thrown higher due to its greater momentum and near-same drag. Both have about the same dead-air duration.
Mike, from my general understanding height gain without sacrificing dead-air duration is the main key. Thermals generally stabilise at some arbitrary distance off the ground.

In order to gain the maximum chance in HLG of snagging one its generally better to design for a higher launch height.

Also a higher average cruise speed provides a shorter duration in sink between area's of lift.

Real sailplanes carry ballast to attempt to cater for all conditions - perhaps a nice lead weight added to our Micro HLG ejected at apogee would serve the same purpose.

The above is my understanding of the general situation, of course I could be wrong.
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Old Oct 09, 2008, 11:39 PM
Team 30 Micro EDF
Mike Taylor's Avatar
Camarillo, California
Joined Apr 2002
4,516 Posts
Charos,

Yes, that is correct. We used to add metal slugs to ballast slope and thermal soarers to match the conditions. The same is also true of indoor HLGs; lighter ones are used for low ceilings, heavier ones for high ceilings.

Since the drag during launch is primarily due to parasitic drag (air flow over the model not directly producing lift), assuming the same frontal area, launch height can be reasonably correlated to mass. You can throw a golf ball a lot farther than you can a ping-pong ball, even if they are close to the same size. Thrown upwards, the golf ball would have better 'duration' as well.

Once at height, the glider's glide angle is a function of its airfoil's L/D ratio. Here, the calculations get rather cloudy, but the suggestion is that a heavier glider goes farther faster. What is vague is whether the sink-rate (altitude lost per unit of time) changes dramatically or not, but the chance of reaching a thermal large enough to circle in are greatly increased.

Thermals start AT the ground (or at least in the surface's boundary layer), but they expand and spread as they move upward. How high you need to be to work lift is pretty much dependent on how tight you can turn the model.

Actually, what strikes me th e oddest is that I, who have been rabid about weight reduction in micros for all these years, find myself arguing in favor of a heavier model

SFA has a pretty large 'glider' sub-forum that has lots of threads/posts that deal with the question of what is the 'right' weight. http://www.smallflyingarts.com/cgi-b...?board=Gliders
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Old Oct 10, 2008, 03:32 AM
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Sydney, Australia
Joined Aug 2008
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General thought seems to be approx 70-90g for the TLG free flight gliders and
approx 25-40g for the HLG free flight gliders.

With upper weight limitations creeping in at or under 50g AUW for the Vapor DSM2 brick perhaps the ideal design would be a smaller lighter Catapult Launched Glider.

I know the design of mine in 2001 was used to great effect as a free flight Catapult Glider but at 35g with battery and brick its probably a little overweight.

Just kicking around thoughts on potential avenues to drive down.
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