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Mar 03, 2005, 09:25 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP

Micro Invent 22g 4-channel No-Cal Extra


I recently got these pictures of a new plane by Micro Invent, a no-cal Extra with full-house 4-channel actuator control. I need to get more details, but it seems the plane was built by Ivan or Robert at Micro Invent. The model made its first appearance at a model meeting in Prague on February 27th. It weighs 22g. The actuators are some new digital proportional actuators. I don't know what that means, or if they are like the ones we generally use, and the digital just means pulsed. The propulsion set is a red Super Slicks 7mm motor in a Gasparin gearbox with a 4:1 gear ratio. From my tests I'm sure the prop is a 5x3. A couple of these are on their way to me in trade for a bunch of SS motors. If a source for the 7mm motors can be found these gearboxes might make it to commercial reality. In one picture you can see the famous Stefan Gasparin holding this model.

As usual the Micro Invent guys do good stuff.

Please note that this plane is from Micro Invent. It is not from Gasparin. Please do not contact Gasparin with any questions. Contact Micro Invent.

Gordon
Last edited by Gordon Johnson; Mar 21, 2005 at 01:27 PM.
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Mar 03, 2005, 09:39 PM
Time wounds all heels.
mmm, 22g full house...and I was so proud of my 22g 2channel Moth, lol. I guess thats what talent and experience gets ya, huh? Sure looks great. Tell him I will buy a whole box of SS motors for one of those.
Mar 03, 2005, 09:59 PM
Micro Flyer, Big Poster
Pete P's Avatar
Wow!! That's Sweet!! Plus, I love those 7mm motors!!
Mar 03, 2005, 10:06 PM
Pro Bro #495
fwilly's Avatar
Any video? Whats the thrust to weight ratio?
Mar 03, 2005, 10:24 PM
Micro Flyer, Big Poster
Pete P's Avatar
Gordon- I'm going to try and call my links over the weekend, see if I can come across anything. If nothing, I can always put a tracking mechanism in a return :-P
Mar 03, 2005, 10:28 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP
You can get a idea of the thrust from my 7mm tests page. I did those tests so I could recommend a gear ratio to Stefan. The red motor at 4:1 and a GWS 5x3 prop develops 25g of thrust. Typically the CF props deliver about 10% less thrust, so probably about 22.5g. I'll know for sure when my gearboxes with the red motor arrive in a week or two. So, that makes 1:1 about for the thrust/weight ratio.

The purple motor would develop about 29g thrust, or about 26g with the CF prop at 4:1.

Stefan will sell the gearbox for 700 czk. I think that would mean you supply your own motor. He may grind down the shafts, so you would need to mail him your motor(s) for him to modify and install the pinion and then send back installed in your gearbox.

Gordon
Mar 04, 2005, 05:36 AM
Sticky Shepherd
Graham Stabler's Avatar
There seems to be a circuit board next to each actuator, they may be using a hall sensor to provide closed loop feedback hence the description.

Graham
Mar 04, 2005, 07:32 AM
Senior to who? Member
crossup's Avatar
Everyone is checking out the gear, Im impressed with the plane.. yet another must build but this is DEFINITELY my style
me:
3 years ago it was fly at under 3 oz...with servos
2 yeas ago it was fly at under 2 oz with servo
last year it was LRF and way under an oz with actuators
now its IMAC in my living room
Mar 04, 2005, 11:29 AM
Pro Bro #495
fwilly's Avatar
I guess its time to start stripping some balsa. I'm thinking micro Pitts Challenger.

Any idea how it was reinforced?
Mar 04, 2005, 11:43 AM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP
I've posted everything I know. All I got were these pictures, the weight, that they were digital proportional actuators, and that it was the 7mm motor in the gearbox. Sorry. I wish I knew more.

Gordon
Mar 04, 2005, 02:07 PM
TheyreComingToTakeMeAway!
derk's Avatar
Gordon did you notice its a twin motor drive? if you look closely at the 2nd one you can see the 2nd pinion gear. also in the one when hes holding it you can see the endbell and wires for it.
so how much better would it be with 2 motors?

Derrik
Mar 04, 2005, 02:43 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP
Derk,
I think they may have different propulsion systems on it in different pictures. It's hard to tell in the pictures, but if one of them is a dual motor system that would likely be his dual 6mm 4.5 ohm drive. They may have been testing both propulsion systems.

My answer to your question is every time I test a dual motor drive the result is the same. You can get better results from a single motor drive with a larger motor. I may be proved wrong on this, but I haven't found a case yet. A friend of mine worked very hard to try and get dual and tri 6mm 4.5 ohm drives to get better results than a M20-MV. He and I compare motor constant results, so he knows what he's doing. In the end he also concluded that he just could not get the results with a multi-motor drive that could beat the M20-MV solution when you take the entire propulsion set and battery pack weight and thrust all into account.

The reason I worked to get Gasparin to make a 7mm drive is my results from testing the 7mm motors indicated it was possible to make a lighter drive with a 7mm motor than with two 6mm motors, and it would develop more thrust and pull fewer amps. MicroInvent reccomends the dual 6mm drive for the Fokker DVII I got from them. Mine is sitting waiting for this 7mm drive as my tests indicated it was the better way to go. That's why I worked to convince Gasparin of this, I did not want to go the dual motor route. I think I convinced Gasparin too.

If you go to Gasparin's site he has test results for his dual 4.5 ohm 6mm drives. If you compare those to the 7mm test results on my site or in the 7mm thread you will see this.

As to a dual 7mm drive, it would weigh more. So, it would need to be compared to a larger motor, something that weighed about 5.4g. A N20 is about in this range. However, the N20's are generally not as good for our purposes as the M20's are. But, I'm pretty sure that a single blue motor 7mm drive would be a better choice than a dual red motor drive.

Gordon
Last edited by Gordon Johnson; Mar 04, 2005 at 02:51 PM.
Mar 21, 2005, 01:29 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP
It's time to bump this thread now that the Extra is shown on Micro Invent's web site under "new", but with no details. Please note that this plane is from Micro Invent. Contact them with any questions. Do NOT contact Gasparin with any questions. It's not his plane. And, at this point the plane is not a kit, or RTF, or ARC. It's a test bed plane for new equipment and may or may not make its way to being commercially available.

Gordon
Mar 21, 2005, 04:01 PM
Registered User
Span ?
Mar 21, 2005, 04:08 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP
Span is unknown. You can probably guess by looking at the pictures.

Gordon


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