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Old Dec 25, 2012, 09:14 PM
Y=C+I+G
cmdl's Avatar
United States, CA, Rosemead
Joined Jan 2012
9,039 Posts
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Originally Posted by Chompwat View Post
All set up and working well! What a beautiful looking plane, that front cowl area is awesome!
Any thoughts on rates please.
i maidened mine on low rates and after a week (flew about 6 flights in first week) flew on high rates.
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Old Dec 26, 2012, 05:59 AM
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Wregie's Avatar
United Kingdom, Middlesbrough
Joined Aug 2011
59 Posts
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Originally Posted by Chompwat View Post
No, I have resisted the temptation so far as my boy wants to learn to fly, and I think I have enough skill learned now for him to buddy box from me.
Once he gets the hang of it I may get the knife out!
Only mod so far is 2.75" wheels for ROG take offs from grass.
I went the same route as you and coped with the t-28 with no problems. It is definitely trickier to land. I found I had to hold it to blend off plenty of speed before the flare or it would balloon.

I ordered a new wing for the SuperCub. I cut out the centre bit to lose the dihedral and shorten it. Added ailerons and a carbon rod. Up front I stuck an eflight power 10. SuperCub on steroids. Unlimited vertical with a crazy roll rate. I would definitely recommend these mods.

I wouldn't go to the field without either the T-28 or the SuperCub

Good luck and go fly
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Old Dec 26, 2012, 10:13 AM
Look ma, no hands!
1Pilgrim's Avatar
United States, WI, Sheboygan
Joined Aug 2011
1,252 Posts
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Originally Posted by Wregie View Post
I wouldn't go to the field without either the T-28 or the SuperCub

Good luck and go fly
For me that's an oxymoron - you obviously haven't seen me fly!

Except for the "skis or floats" crowd outdoor flying is over 'til April in these parts. Looking forward to seeing how the T-28 handles the Dubro 2.5" wheels and 3-bladed prop! I'm also eager to experiment with different cg locations - I'll post the method my "real aircraft" builder and flier son taught me for finding the actual cg.
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Old Dec 26, 2012, 12:18 PM
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1Pilgrim's Avatar
United States, WI, Sheboygan
Joined Aug 2011
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Finding the actual cg on the T-28

Procedure for finding the actual center of gravity
1. Place the aircraft on a flat, level, markable surface with all accessories (batteries, cameras, etc.) in flight position.
2. Draw a line on the markable surface long enough to pass under the spinner and between the main landing gear - the "center line".
4. Draw another line perpendicular to the center line where the main gear will be placed - the "main gear line"
5. Chock the main wheels so their hubs are centered over the main gear line; center the nose wheel (or tail wheel) on the center line.
6. Draw a point below the center of the nose wheel (or tail wheel) - the "nose/tail wheel point".
7. Draw a line through the nose/tail wheel point perpendicular to the center line - the "nose/tail wheel line"
8. Use a tee- or right-angle ruler to draw a point on the center line directly under the end of the spinner - the "datum point".
9. Draw a line through the datum point perpendicular to the center line - the "datum line".
10. Measure the distance between the datum line and the main gear ine to the nearest 1/32" - the "main gear arm".
11. Measure the distance between the datum line and the nose/tail wheel line to the nearest 1/32" - the "nose/tail wheel arm".
12. Weigh the aircraft at each wheel to the nearest 0.1 g.
NOTE: As the scale is placed under each wheel, block up the other wheels to the height of the scale.
13. Multiply each arm by the corresponding weight to obtain the moment at each wheel.
14. Add up the weights and moments and divide the Total Moment by the Total Weight to obtain the actual "Center of Gravity" in inches.

In this example the location of the actual center of gravity is measured aft from the end of the spinner.
Using the point at the end of the spinner for the datum is purely arbitrary - any point on the center line away from the wheel lines will work.
Using a convenient datum point somewhere on the aircraft makes it easier to visualize and locate the actual cg

Compare the actual cg to the mfr's recommended nominal cg for the T-28 (2.5" aft from the leading edge to the thickest part of the wing - pretty standard for this type of aircraft). I found out that the actual cg as almost 3/4" ahead of the maximum chord on my plane; that explains why I had to use so much elevator trim to get it to fly level!

I drew my lines on a piece of poster board and am keeping it so I can easily recalculate the actual cg any time. This helps me see the effect of moving things around and/or changing the weight of the airplane, especially the battery. I'll be shifting the battery aft 1/8" at a time until the actual cg lines up with the maximum chord, test flying the plane after each change just to be safe!

You can easily adjust the actual cg forward or backward to change the flight characteristics on purpose or by accident.
Proceed with caution: adjusting the actual cg too far from the recommended location will render the aircraft unflyable!!!
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Old Dec 26, 2012, 07:54 PM
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1Pilgrim's Avatar
United States, WI, Sheboygan
Joined Aug 2011
1,252 Posts
Moving the stock 1100 mAh battery back an inch only moved the cg back about 1/4". Does this seem reasonable?
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Old Dec 26, 2012, 10:07 PM
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cmdl's Avatar
United States, CA, Rosemead
Joined Jan 2012
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i thought the stock battery is an 1800
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Old Dec 26, 2012, 10:23 PM
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1Pilgrim's Avatar
United States, WI, Sheboygan
Joined Aug 2011
1,252 Posts
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Originally Posted by cmdl View Post
i thought the stock battery is an 1800
DOH! My bad - I do have the 1800mAh loaded up. Question remains - would moving the battery back an inch move the cg back a quarter inch? It looks about right but I don't have a lot of experience with the T-28.
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Old Dec 26, 2012, 10:41 PM
Joined Nov 2011
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Originally Posted by 1Pilgrim View Post
DOH! My bad - I do have the 1800mAh loaded up. Question remains - would moving the battery back an inch move the cg back a quarter inch? It looks about right but I don't have a lot of experience with the T-28.
You do have an interesting technique for locating the CG though. Using the same scale and a little math you can figure out exactly how much any given component would change the CG if it were to be moved or removed.
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Old Dec 26, 2012, 11:08 PM
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1Pilgrim's Avatar
United States, WI, Sheboygan
Joined Aug 2011
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Originally Posted by Logan4169 View Post
You do have an interesting technique for locating the CG though. Using the same scale and a little math you can figure out exactly how much any given component would change the CG if it were to be moved or removed.
My son says that he has to figure weight and balance down to the last iota on his sport plane - the safe cg range is only 4"! The "hang test" balancing technique typically used in rc land is neither practical nor accurate when applied to full scale aircraft!

Can you explain how to calculate the change in CG when the battery is moved? It's easy enough to just shift the battery, re-weigh the airplane at each axle and plug the new weights into my spreadsheet to precisely locate the new CG but I'd like to see how you do it.

These are my measurements and calculations


Left Main Wheel Wt = 364.1 grams, Arm = 12.344 inches, Moment = 4494.36 inch grams

Right Main Wheel Wt = 355.3 grams, Arm = 12.344 inches, Moment = 4385.73 inch grams

Nose/Tail Wheel Wt = 218.2 grams, Arm = 4.625 inches, Moment = 1009.18 inch grams

Total Wt = 937.6 grams, Arm = 20.597 inches, Moment = 9889.27 inch grams

CG = 9889.27 inch grams divided by 937.6 grams = 10.547 inches aft of spinner
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Old Dec 26, 2012, 11:20 PM
wjs
William
United States, MI, Brighton
Joined Oct 2012
1,966 Posts
Quote:
Originally Posted by 1Pilgrim View Post
DOH! My bad - I do have the 1800mAh loaded up. Question remains - would moving the battery back an inch move the cg back a quarter inch? It looks about right but I don't have a lot of experience with the T-28.
Sounds about right. However, depending on plane, cg moves and tipping is not linear. Moving it back a 1/4 may be a slight tip forward. Another 1/8 may be full down and way too much.
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Old Dec 26, 2012, 11:45 PM
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1Pilgrim's Avatar
United States, WI, Sheboygan
Joined Aug 2011
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Originally Posted by wjs View Post
Sounds about right. However, depending on plane, cg moves and tipping is not linear. Moving it back a 1/4 may be a slight tip forward. Another 1/8 may be full down and way too much.
Ooh, that's right - my calculation only applies if the plane is flying straight and level. I'd better leave the calculated cg far enough forward so I don't get into trouble when pitching up. Thanks!
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Old Dec 26, 2012, 11:47 PM
Stitching 'em back together!
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United States, MO, Lee's Summit
Joined Jun 2012
492 Posts
Hi T-28 pilots,

I am currently flying a P-47 and have been since summer. Recently I was able to try a T-28 and really enjoyed flying it. That got me playing with it on my sim (Phoenix) and I find that I am a lot more confident and willing to try more while flying it. So now I am really considering getting one. There are a few others I am looking at adding to my fleet but this one keeps bringing me back to the "add to cart" section on Horizon.

So am I just having a crush on this plane because I had one really fun flight or is it really as fun to fly as the Sim makes it out to be? Should I consider something else? Maybe the SE5a or an ultra micro perhaps?

Please don't get me wrong I really like the P-47 but I want to add something to my fleet and at this time would like something a bit slower and fun to push the envelope with. I can honestly say I have not found the edge with my jug yet as it can far out perform me.
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Old Dec 26, 2012, 11:54 PM
Look ma, no hands!
1Pilgrim's Avatar
United States, WI, Sheboygan
Joined Aug 2011
1,252 Posts
Quote:
Originally Posted by stitch1 View Post
Hi T-28 pilots,

I am currently flying a P-47 and have been since summer. Recently I was able to try a T-28 and really enjoyed flying it. That got me playing with it on my sim (Phoenix) and I find that I am a lot more confident and willing to try more while flying it. So now I am really considering getting one. There are a few others I am looking at adding to my fleet but this one keeps bringing me back to the "add to cart" section on Horizon.

So am I just having a crush on this plane because I had one really fun flight or is it really as fun to fly as the Sim makes it out to be? Should I consider something else? Maybe the SE5a or an ultra micro perhaps?

Please don't get me wrong I really like the P-47 but I want to add something to my fleet and at this time would like something a bit slower and fun to push the envelope with. I can honestly say I have not found the edge with my jug yet as it can far out perform me.
It really is all of that!
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Old Dec 26, 2012, 11:58 PM
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cmdl's Avatar
United States, CA, Rosemead
Joined Jan 2012
9,039 Posts
Quote:
Originally Posted by stitch1 View Post
Hi T-28 pilots,

I am currently flying a P-47 and have been since summer. Recently I was able to try a T-28 and really enjoyed flying it. That got me playing with it on my sim (Phoenix) and I find that I am a lot more confident and willing to try more while flying it. So now I am really considering getting one. There are a few others I am looking at adding to my fleet but this one keeps bringing me back to the "add to cart" section on Horizon.

So am I just having a crush on this plane because I had one really fun flight or is it really as fun to fly as the Sim makes it out to be? Should I consider something else? Maybe the SE5a or an ultra micro perhaps?

Please don't get me wrong I really like the P-47 but I want to add something to my fleet and at this time would like something a bit slower and fun to push the envelope with. I can honestly say I have not found the edge with my jug yet as it can far out perform me.
the t-28 is a lot of fun to fly, specially to push the envelope. on my flights i fly my spit first and its a lot more fun to take it easy with the t-28 right after. she handles loops, rolls, inverted flying very well at low and high speeds.
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Old Dec 27, 2012, 12:00 AM
We got some flyin' to do!
Justwingit's Avatar
United States, CA, Fort Irwin
Joined Apr 2012
5,213 Posts
Get one stitch and Just Fly!

I'm telling you, flying this thing never gets old....Carlos (PittSpecial) has been flying the same one for over six years...! A very durable and fun model that will surely continue to grow with you for years to come. Uses the same prop and batteries as the P-47 if I'm not mistaken, so that's an added bonus

It goes with me every time I go to the field...
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