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Old Jun 20, 2004, 10:26 AM
Registered User
Belgium
Joined Jun 2004
344 Posts
Cool
Ralph Bradley's 7.75-inch MicroMite

Hi,

This is my first post on this forum. I have to say I'm impressed! I have been building small planes for almost a year in quite some isolation ... but I've found tons of info this forum already.

I build a micro mite (http://www.parmodels.com/Plans/Micro%20Mite.pdf) with a KP-00 geared motor recently (not yet flown). I was wondering if a direct drive DIDEL 4.5 ohm pager would also do the job?

Regards,
Johan
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Old Jun 20, 2004, 03:54 PM
Faroe Islands/Germany
epilot's Avatar
Joined Nov 2000
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I doubt it would work DD but geared and with a small cell (60mah) it should work.

Michael
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Old Jun 20, 2004, 04:06 PM
Sticky Shepherd
Graham Stabler's Avatar
Oxford/England
Joined May 2001
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I would build as the plan is drawn first, then try to experiment.

Graham
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Old Jun 20, 2004, 05:04 PM
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Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
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Johan, welcome to RC Groups.

I concur, build as specified the first time with the model. However, some limited direct drive static tests of the 4.5 ohm pager model are in the current Inside Story column (see the micro threads index). Note that DD static tests are less relevant, so you would still have some trial and error in the plane. Just read the article. It's all there.

Gordon
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Old Jun 20, 2004, 05:23 PM
Registered User
Belgium
Joined Jun 2004
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I tried to run the micro mite from a geared KP-00. Total weight of the plane is 18 grams. I had the impression the trust was not enough (plane crashed). I'm using the white propeller with 2 blades that comes with the KP-00. I've provided the same down thrust as on the plans ...

So, I was wondering if I needed to build it lighter (hence the DD pager motor) or do something else ...

Can it be that the angle of the main wing and the elevator is wrong?

Johan
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Old Jun 20, 2004, 05:45 PM
Sticky Shepherd
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Oxford/England
Joined May 2001
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The plan shows a direct drive KPOO, why not use that and try to get the weight the same as the model in the plan. You may not want as much downthrust with the geared motor.

There are many reasons that it might have crashed. One likely one is a slow launch.

Graham
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Old Jun 20, 2004, 06:12 PM
I'm Me Again!
Jerry Rose's Avatar
Joined Feb 2002
434 Posts
Just an observation ...

Quote:
Originally Posted by nanoflite
I'm using the white propeller with 2 blades that comes with the KP-00. Johan
The plan calls for a U-80 prop, cut down to 2 1/8 inch diameter. I don't think they are white ... and if not, you've deviated from plan quite a bit. That might make quiet a difference.
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Old Jun 20, 2004, 06:15 PM
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Belgium
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I wasn't aware the micro mite used a direct drive KP-00. I'll try to redo the fuselage with the direct drive version. I do however have the impression that my plane is bit nose-heavy, probably because of the extra weight of the gears...

One thing I don't quite understand is why I need less downtrust with a geared motor?

Thanks for the tips!

Johan
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Old Jun 21, 2004, 10:09 AM
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Brandon Mississippi/Independence Kentucky
Joined Oct 2000
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I'm afraid I can't offer any opinion on a model not built to the plan without seeing it first hand. If built to the plan it should fly as heavy as 20 grams (with the LV motor). Here are a few photos of the original that the plan was drawn from. The first shows the original equipment installation with a GWS 05 and a votage booster. It was rudder only at this time and in the flight pictures here. I replaced the votage booster and 05 motor with a LV M20 and eventually added a second actuator for elevator. First flights were at 16 grams. The final configuration weighed 17.5 grams with a 140 cell. I have included a picture of the model just after launch that shows the typical climb angle for this model as described by the plan.

Ralph
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Old Jun 21, 2004, 10:47 AM
Registered User
Belgium
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Thanks for the insight! I'm going to rebuild the micro mite and will try to follow the plan as close as possible (given the hard to find parts?) ...

Would a KP-00 motor do the job? Also, I wonder where I can get the U80 props in europe ...

Also, another question I have is about the angle of attack between elevator and wing. What is the correct setting? Also, where exactly is the CG? On the plans it is pointed at on the bottom of the fuselage, but I can get 2 points on the wing if I project the CG perpendicular to the wing cord or the fuselage ...

I've some photos here, maybe something obvious is wrong with the way i build it?

Also, let me say I'm impressed with your plans Ralph! Thank you very much for them!

Johan
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Old Jun 21, 2004, 12:58 PM
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Brandon Mississippi/Independence Kentucky
Joined Oct 2000
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Johan:

It looks like you did a very nice job on your Micro Mite (especially the tissue trim!). I'm sure once you try the direct drive it will fly. The KPOO motor is a LV M-20 so yes that will work fine. If you look at the picture of mine you will see that I have also used the GWS 1" X 2.5" prop cut down. There is information in the "Inside Story" archive that explaines how to trim the prop.
I never did measure the incidence angle. The plan was drawn from the actual templates that built the original model. As long as you reproduce the parts as drawn, you will have the correct angle set when you assemble the parts. For your first flight set the CG 5/8" back from the leading edge of the wing. The best location for your model may require some fine tuning once you start test flying. It's not unusual to have a little variation from one model to the next.

Ralph
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Old Jun 21, 2004, 01:09 PM
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USA, FL, Fort Lauderdale
Joined Feb 2002
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Johan,

I'll add a little something, with Ralph's approval of course. For a plane that size, particularly with control surfaces that small, I think you could get away with much smaller/lighter actuators. Michael (epilot) has posted much about the construction of small actuators, I would think something with #41 or #44 (USA AWG) wire and some 1/8" diam x 1/16" thick magnets would do the job at half the weight. My 2 cents.

Ralph, could you chime in on feasibility of BIRD style acts. on either one or both of the controls? They would really save weight, if it could still be balanced. (selfish question, this plane is high on my list).

Dave
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Old Jun 21, 2004, 02:26 PM
Faroe Islands/Germany
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I make 50ohm actuators using 0.05mm wire. With two 3x1mm magnets they weigh 0.38 grams and are plenty strong for a plane like the MiMi. Here is a picture of one. I might be going into limited production of these. It uses etched brass parts. Difficult to photograph because it is shiny. Adding biasing magnets would increase weight to around 0.4 grams.

Michael
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Old Jun 21, 2004, 02:29 PM
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Brandon Mississippi/Independence Kentucky
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Dave:

My 9" version of this model had rudder only via one tail mounted actuator. Tail mounted actuators would work but I suspect the weight savings would be more than offset by ballast on the nose. I don't think you would have enough room to move the battery (especially if you used a 60 cell) and receiver far enough forward to avoid having to add nose weight to compensate for the tail mounted actuators.
If you start with The Selman mini actuator kit and use 3MM magnets plus a relay wire coil you can produce a 0.4 gram actuator. Even if you use the stock mini's with smaller magnets the Micro Mite can handle it with no problem. That's really the point of the Micro Mite. It's an off the shelf deal that can fly in a little bit of wind.

Ralph
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Old Jun 21, 2004, 02:59 PM
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USA, FL, Fort Lauderdale
Joined Feb 2002
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Ralph,

Thanks, I thought I remembered one of your smaller mites with the bird act., but no sense saving weight with the bird actuators and having to add it back to the nose. Still, lighter remote acrs. would be a good weight savings.

Michael,

Looks like someone's been busy, I like the shiny brass, can I return mine?

Dave
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