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Old Nov 09, 2011, 06:27 PM
I fly wood.
Bob from MD's Avatar
United States, MD, Columbia
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Yes, the shop is clean, for now. I finished the remodel not too long ago and haven't gotten into many builds since then. Also, I did a clean up for the pictures. Not to worry, it will get back to its normal state before too long. I'll show you a picture of the mess in my office upstairs which is more the norm.

Bob
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Old Nov 09, 2011, 09:52 PM
MrE
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Quote:
Originally Posted by jpherit View Post
I would just like to add my experience with the single elevator on my Nostalgia legal winch towed Mirage.

The single elevator on the stock plane is more than adequate for most flying requirements. ...snip....Of course, it is your choice to change over to dual elevators and that is fine, but I just wonder if it is still a Mirage?
Another thing to consider on elevator authority is CG position. The further back you have it the better your elevator authority will be.

As for the question of "is it still a Mirage?", thats a good question. Just how many things, and which things, can you change before you go 'too far' and cant call a model by its original name?

Is adding a motor enough to cause you to stop calling it a Mirage? I think calling it a Mirage is fine but maybe E-Mirage would be better.

Certainly if you intend to compete in nostalgia or similar contests you are pretty limited on what you can do.

I have no desire to enter into that type of competition, so I feel free to "kit bash" to a large degree and still call it a Mirage.

I changed a whole lot of details on the fuse and tail feathers from adding the motor to enlarging and making small changes to the outline of the rudder and elevator, getting rid of the balance portion of the rudder, locating the rudder on the center line, dual elevators, making the rudder and elevator removable, no push rods, no tow hook etc.

On the other hand, my wing is more "stock" than yours is, but the carbon you added is invisible and 'legal'.

If our two models were sitting side by side I think that, other than the prop up front, most people would think they were the same model - unless they looked closely at the tail feathers.

On the Houston Hawk build Im about to do I intend to change even more of the "details".

Im starting from the original plans and will use most of the kit wing components and keep the wing planform and outlines the same, but a lot of the structural details will be different - from the spar to the wing span.

The fuse I feel more freedom to mess with as the Houston Hawk doesnt really have an original fuse any more. Its no longer available, so you have to do things at least slightly different on that. Im going to do them radically different though.

Still, I feel like I need to call it a Houston Hawk or some variation on that name just to give credit to the original designer, Jack Womack. Im not really scratch building, Im starting from his creation.

He did the hard part. All Im doing is fiddling with the details
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Old Nov 10, 2011, 09:29 PM
MrE
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I got my new Graupner CAM prop blades in today and managed to get the Mirage back together for some test flights.

I just finished crunching the numbers on several flights on 2S and 3S packs.

I am absolutely shocked to find that the APC folders perform better!!!!!!!

Not by much but there is a significant difference. the APC's were averaging right at 9 feet/min/watt and the Graupner CAM is averaging 8.5 ft/min/watt.

Im going to have to try this again and play some more with different climb angles. I just find it hard to believe the cheap APC's are better than the CAM.
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Last edited by MrE; Nov 10, 2011 at 09:49 PM.
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Old Nov 11, 2011, 12:15 AM
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granada don's Avatar
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Hi E

That is very interesting, last yr there was the thread on broken prop blades how do you feel about using the APC vr's the good stuff, as it can cost a lot bucks if you have a blade break off. I would rather spend more and not worry about failure.

G Don
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Old Nov 11, 2011, 01:36 AM
MrE
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Normally I agree with you Don.

The new graupner blades are the smoothest and quietest running of all the ones Ive tried so far.

The APC's are noisy and hard to balance, yet they are more efficient at climbing than the CAM prop.

Im definitely going to repeat the testing and play with climb angles some more. I may have just not found the best angle for the CAM prop.
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Old Nov 11, 2011, 07:07 AM
Herk
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Virginia USA
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MrE I'm kind of lost in EMP Cam and APC with diameters and pitches mentioned here and there - it's hard to follow all the pieces.

Please take a minute and give us a breakdown of brand diameter and pitch you are trying. If you mix in different pack voltages, please put them in the breakdown along with your power and performance readings. This is very interesting stuff. You have done a lot with it. Would be nice to have it tabulated for the record.

It would also be interesting to hear your reflections on the original low power concept of your first few posts
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Old Nov 11, 2011, 10:43 AM
soaring guy
USA, AZ, Mesa
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G Don

I have a Hyperion GS 2213/20 (no longer marketed) in a Skybench 2M Lil Bird.
Using a 10/6 CAM prop the wattage is right where the Hyperion stats say it should be. I have been impressed with the quality of the motor, Probably have well over 100 climb outs and no problems.

Bought a CAM unit for some ALES comps and I am trying to learn where the motor cut out will be so I don't do a 100 foot tail slide. Always something to work on.

Dee
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Old Nov 11, 2011, 10:10 PM
MrE
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Quote:
Originally Posted by HerkS View Post
MrE I'm kind of lost in EMP Cam and APC with diameters and pitches mentioned here and there - it's hard to follow all the pieces.

Please take a minute and give us a breakdown of brand diameter and pitch you are trying. If you mix in different pack voltages, please put them in the breakdown along with your power and performance readings. This is very interesting stuff. You have done a lot with it. Would be nice to have it tabulated for the record.

It would also be interesting to hear your reflections on the original low power concept of your first few posts
Lets try this for starters. I need some time to go back and find all the exact numbers, but I'll give you the end result for starters.

I'll just list the numbers that were all run on the Hacker A20-20L motor. The other motors I tried are no longer available. All the props have been tried on 2S 1600 and 3S 1100 25C Hyperion CX packs.

I guess I should list the static wattage for those guys who dont have access to loggers, but I need to go back and look that up.

The way Im comparing the props is to look at how many watts they use in the climb rather than static. Doesnt really matter what the static power is, its the watts while climbing that matter. IIRC most of these setups have been unloading about 15%-20% in the air.

APC folding props -10x6 and 11x8 - Averaged just over 9 feet/minute climb rate per watt of power IN THE AIR durring the climb. The highest I saw was about 9.5.


Next best:
Graupner CAM 11x6. It averaged about 8.5 with a hi around 8.8 ft/min/watt

Last place goes to the EMP folding props - 10x6 and 11x8 - averaged about 6.9 with a hi of 7.3 ft/min/watt. These guys are clearly the least efficient at climbing.

Over the weekend I will put together a better table or something with the actual wattage and climb numbers and rpm etc.
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Old Nov 11, 2011, 11:06 PM
MrE
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Quote:
Originally Posted by HerkS View Post
MrE I'm kind of lost in EMP Cam and APC with diameters and pitches mentioned here and there - it's hard to follow all the pieces.
...snip...
It would also be interesting to hear your reflections on the original low power concept of your first few posts
Forgot to answer your last question.

Let me get back to you on that... got to rush off to a kitten emergency...
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Old Nov 11, 2011, 11:26 PM
life long racing nut & modeler
granada don's Avatar
Granada Hills Ca.
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Hi E

I looked at the Hyperion spec's and it looks like i will have 100 Watts 39 Amps per lb using a 13-8 prop with a 14-8 it is 140 Watts 45 Amps per lb.

So i will go with the smaller prop and keep it on the mild side and not over tax the set up, looks like i will be able to get back up wind with the flat bottom wing and have a good climb rate too for a 60 oz plane.

G Don
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Old Jan 12, 2012, 11:49 PM
MrE
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Between weather and STUFF, I havent had a chance to get much flying in the last few months. I've flown in a couple of ALES contests but thats about it.

Im hoping to get out tomorrow and do some more prop testing. I still cant believe that those cheep APC folders are out performing the Graupner and Aeronaut props.

It occured to me that maybe the reason for the discrepancy was that I was running the tests on different days. Perhaps weather is effecting the results. I ran the APC tests on relatively warm days and the others of colder days. Those performance numbers Ive been coming up with are actually an over all performance number and not just a prop efficiency comparison. Motor efficiency plays a big part in those numbers.

So - if the weather will cooperate tomorrow, I plan to try to fly all three prop types back to back using the same packs on all and trying to fly as close as possible, the same flight profile.

Thats about the best I can think of to get some fair comparison numbers between the three props.

We will see....
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Old Jan 13, 2012, 12:07 AM
MrE
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Oh, by the way, in the last ALES contest I was averaging 27 seconds to get to 200 meters.

Thats on a total of right at 210 watts static on a 2 pound plane so about 105 watts per pound static. In the air it was averaging 90 watts per pound. Temps were in the 40's that day and moderate humidity levels, light wind.

Im climbing out at roughly 40 degree angle at a guess. When motor cut off occurs, the model is so far out and so hi, that its beyond the range where I have the ability to see it well enough to judge if its in lift or sink.

In other words, more power isnt going to do me any good. It might actually hurt!
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Last edited by MrE; Jan 13, 2012 at 12:12 AM.
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Old Jan 13, 2012, 01:14 AM
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Hi E

Years ago i used to build racing engines and test them on a dyno, and you would keep tract of the air temp - humidity etc and those numbers would make up a correction factor. that way whatever the weather was it did not matter as the factor would make it right no matter where you were in the land nite or day.

Write it all down and you can kinda figure it out after awhile. Just the facts mam.

G Don
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Old Jan 14, 2012, 10:38 PM
MrE
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I wish I had that constant already figured out Don

The weather didnt cooperate, so till next time....
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Old Jan 15, 2012, 12:22 PM
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I have always wanted to make an electric Mirage...El-Mirage?

I'm not to well versed in the electric side of things. So many power setups. It gets confusing. Is there a current Hyperion motor that will work well?

I had a customer back a few years ago increase the rib spacing on the tips to stretch the span and went to a V-Tail. He used it as a test bed for a telemetry system for a UAV.

Mark
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