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Hi-Performance and Sailplanes RC hotliners, electric pylon racers, F5B, F5D, sailplanes and gliders

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Old 12-06-2012, 09:32 PM   #1
dheaton
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So I have a question for all you flyers out there. Have you ever flown in thermals when taking off from 7600 feet. That is the elevation I live at and it is real hard to find anything.
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Old 12-07-2012, 12:12 AM   #2
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Ive been close = about 6500-7000 flying near Lake Tahoe, California. I had more trouble with trees than poor lift

Higher altitudes do mean the air is thinner, so lift is less to some degree. You should still be able to climb in a good one though.

Where are you flying?

I think I need a signature.
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Old 12-07-2012, 01:34 AM   #3
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Just about 5 miles from my home is a dirt runway that doesn't get used very much so I fly (try) there. I used to live in Vegas and had no problems finding thermals there but here is a different story. I think I may have to go to electric for everything. I have several gas models but they scare me so I think I will stick to that. Lots to learn though.


Originally Posted by Larry3215 View Post
Ive been close = about 6500-7000 flying near Lake Tahoe, California. I had more trouble with trees than poor lift

Higher altitudes do mean the air is thinner, so lift is less to some degree. You should still be able to climb in a good one though.

Where are you flying?
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Old 01-03-2013, 07:24 PM   #4
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Sounds like you are an experienced thermal pilot so I am not going to offer any tips on thermal soaring.

What are your wind conditions?

At that elevation I get the impression you are in a mountanous are high plateau area. Are there any suitable slope soaring sites? Your profile does not indicate where you live.

Slope soaring may be a good alternative if you have no success with thermals.

How Slope Soaring Works
http://users.iafrica.com/s/st/stevemac/afc/ssoar.html

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http://www.shallowsky.com/planes/weasel/slopetips.html

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Old 01-04-2013, 01:15 AM   #5
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I don't know how experienced I am with thermals but I have flown in them and have had some fairly long flights. That was in Vegas with 100 degree temps.
I live in the mountains of Utah and where I live I really have not been able to find a suitable slope with which I would be able to soar. I could do it but if I made a mistake I would loose the plane all together because I would not be able to retreive it.
I used to slope soar with a few foames that I built and that was fun but if I crashed (when) I was able to walk down the hill and pick up the plane. That was in a different location in Utah called Cedar City.



Originally Posted by AEAJR View Post
Sounds like you are an experienced thermal pilot so I am not going to offer any tips on thermal soaring.

What are your wind conditions?

At that elevation I get the impression you are in a mountanous are high plateau area. Are there any suitable slope soaring sites? Your profile does not indicate where you live.

Slope soaring may be a good alternative if you have no success with thermals.

How Slope Soaring Works
http://users.iafrica.com/s/st/stevemac/afc/ssoar.html

Slope soaring Tips for Beginners
http://www.shallowsky.com/planes/weasel/slopetips.html
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Old 01-04-2013, 01:18 AM   #6
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Originally Posted by dheaton View Post
I don't know how experienced I am with thermals but I have flown in them and have had some fairly long flights. That was in Vegas with 100 degree temps.
I live in the mountains of Utah and where I live I really have not been able to find a suitable slope with which I would be able to soar. I could do it but if I made a mistake I would loose the plane all together because I would not be able to retreive it.
I used to slope soar with a few foames that I built and that was fun but if I crashed (when) I was able to walk down the hill and pick up the plane. That was in a different location in Utah called Cedar City.
Where are you at in Utah? It actually has one of the best slope sites IN THE WORLD maybe even the universe.

Point of the Mountain.

Mike
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Old 01-04-2013, 01:29 AM   #7
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Ya the point of the mountain is awesome. I live about 5 hours southeast of there in a little town called Boulder. It is in the mountains at 7600 feet and a population of 180 people.
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Old 01-04-2013, 02:09 AM   #8
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Never heard of it and I lived in Utah for almost 12 year. Now you have me google mapping.
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Old 01-04-2013, 02:19 AM   #9
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Where do you live?
That is funny because Before I moved here I had never heard of it as well. It is right near Capitol Reef on HWY 12. It is a very beautiful location. I have been here for about 20 years now.


Originally Posted by rcers View Post
Never heard of it and I lived in Utah for almost 12 year. Now you have me google mapping.
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Old 01-04-2013, 02:22 AM   #10
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What kinds of prop nuts do you guys use. I see there are ones with colletts and ones with little set screws. I purchased one from the hobby store that is a collett one but had no idea which is better. Kind of worried about it coming off.
Plane is almost ready to fly. I need to determine the CG point. It is not listed in the plans or manual that came with the plan. It is over 20 years old. Any thoughts on CG?
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Old 01-04-2013, 02:38 AM   #11
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Originally Posted by dheaton View Post
Where do you live?
That is funny because Before I moved here I had never heard of it as well. It is right near Capitol Reef on HWY 12. It is a very beautiful location. I have been here for about 20 years now.
Provo for school and SLC for 7 years.

I like the collet type FAR better than set screws. I have had had collet type prop adapters at well over 1,000 watts. Tighten them properly and they are fine.

For CG start with 25% mean chord and should should be plenty nose heavy. Is the wing and tail standard on the plane? (That matters too...)

Mike
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Old 01-04-2013, 02:57 AM   #12
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I have a daughter that lives in Provo.
Dumb question but what do you mean by 25% mean. Can you be more specific?
The kit is an electric Scout with 48" wing span. As far as standard goes I have no idea what that means. I have been talking to some people about this plane and setting it up here http://www.wattflyer.com/forums/show...d=1#post894603
Any help is appreciated.


Originally Posted by rcers View Post
Provo for school and SLC for 7 years.

I like the collet type FAR better than set screws. I have had had collet type prop adapters at well over 1,000 watts. Tighten them properly and they are fine.

For CG start with 25% mean chord and should should be plenty nose heavy. Is the wing and tail standard on the plane? (That matters too...)

Mike
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Old 01-04-2013, 05:52 PM   #13
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Originally Posted by dheaton View Post
I have a daughter that lives in Provo.
Dumb question but what do you mean by 25% mean. Can you be more specific?
The kit is an electric Scout with 48" wing span. As far as standard goes I have no idea what that means. I have been talking to some people about this plane and setting it up here http://www.wattflyer.com/forums/show...d=1#post894603
Any help is appreciated.
Divide the wing in 4 sections (25%) from the front to back. So if the chord of the wing is 8" the CG at 25% is 2" from the leading edge. You can move it back slowly from there.

Most planes are about 28-32% MAC (mean aerodynamic chord).



But I can save you a bit of time - on that plane just start on the spar.

Mike
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Old 01-04-2013, 05:57 PM   #14
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Thanks Mike
Wow, if that is the CG then it is even more tail heavy than I thought. This kit called for a .05 can motor which is much heaver so that is part of the tail weight issue. I hate to add weight to the front but I may have to.


Originally Posted by rcers View Post
Divide the wing in 4 sections (25%) from the front to back. So if the chord of the wing is 8" the CG at 25% is 2" from the leading edge. You can move it back slowly from there.

Most planes are about 28-32% MAC (mean aerodynamic chord).



But I can save you a bit of time - on that plane just start on the spar.

Mike
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Old 01-04-2013, 06:24 PM   #15
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Originally Posted by dheaton View Post
Thanks Mike
Wow, if that is the CG then it is even more tail heavy than I thought. This kit called for a .05 can motor which is much heaver so that is part of the tail weight issue. I hate to add weight to the front but I may have to.

Can you move your electronics forward more? do you have it flight ready and checking the CG with battery and everything installed ready to fly?
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Old 01-04-2013, 07:01 PM   #16
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It is pretty close to flight ready, I just have to make a tail dragging system. The plans called for putting the servos close to the back of the wing opening and I could move them I guess although they are very light weight. I put the battery right up front were the (called for) motor was supposed to go and it is still tail heavy.

Originally Posted by BBCorvette18 View Post
Can you move your electronics forward more? do you have it flight ready and checking the CG with battery and everything installed ready to fly?
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Old 01-04-2013, 10:14 PM   #17
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dheaton
How far back does it currently balance? (as a % of the wing chord)
As Mike says 25% is a good safe starting point.
30% might be possible but undertaking the first flight with the CofG at this position would be risky.
Over 30% back is most likely to end in a crash!
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Old 01-04-2013, 11:11 PM   #18
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The wing is 8 3/8 wide and it ballances 3 3/8 from the leading edge. The main spar is 1/4" thick is starts at 2 3/4 from leading edge and ends at 3"
Does that make sense?


Originally Posted by quorneng View Post
dheaton
How far back does it currently balance? (as a % of the wing chord)
As Mike says 25% is a good safe starting point.
30% might be possible but undertaking the first flight with the CofG at this position would be risky.
Over 30% back is most likely to end in a crash!
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Old 01-05-2013, 11:10 AM   #19
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Balancing 3 3/8 (3.375) back on a wing 8 3/8 (8.375) wide is

3.375/8.375 * 100 = 40,3%

Unless the wing has significant sweep back I would not even attempt to fly with the CofG in that position.
If you cant move anything forward then add weight right at the front to get much closer to 25% or 2.1" (2 1/8) back from the leading edge.

Hope that helps.
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Old 01-05-2013, 03:11 PM   #20
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I agree that starting on the main spar or about 30% back from the leading edge at the root would be good. However, I think I flew my Sagitta 600 at 36% back from the leading edge. And I had a slope glider that balanced at 38%.

These are conventional wing glides. I am not sure how one finds the design CG for a flying wing.

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Old 01-06-2013, 06:34 AM   #21
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What is the best weight to have to add to the plane? Fishing sinkers?
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Old 01-06-2013, 06:54 AM   #22
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I think it would depend how much you need to add but I would go with the tire weight tape things. Should be able to get them secure and and as far away from the cg point as possible so you can add the least amount of weight possible to achieve the proper cg
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Old 01-06-2013, 01:13 PM   #23
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I use fishing weights. Or the stick on weights like these:

http://www3.towerhobbies.com/cgi-bin...?&I=LXK204&P=7

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Old 01-06-2013, 01:36 PM   #24
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Ya I think I may even have some of those.



Originally Posted by rcers View Post
I use fishing weights. Or the stick on weights like these:

http://www3.towerhobbies.com/cgi-bin...?&I=LXK204&P=7

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Old 01-06-2013, 03:13 PM   #25
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Depends on how much you need to add.

I use coins, stick on weights or sometimes I use lead shot and epoxy to form a custom size and shape weight if the need is large enough.

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