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Old May 04, 2011, 01:49 AM
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scottd9990's Avatar
United States, NC, Charlotte
Joined Jun 2009
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stock 737 retracts

What's necessary to beef up the stock units?

S
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Old May 04, 2011, 08:41 AM
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Southern California
Joined Mar 2010
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Pulsery2k1 How is the painting coming along? I am anxious to see some progress.
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Old May 05, 2011, 12:01 AM
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Doug W's Avatar
United States, WA, Seattle
Joined Jul 2010
445 Posts
So does this 737 make me look fat?

I recall Ben_E saying to stay out of the 9+ weight range...question for the group (opinion on added lipo weight v flying time).

I've got all this wonderful high lift stuff- flaps will add a ton of lift for sure, and thus far, I am in at 6.7 pounds (I am not fully assembled, but it is all on the scale, minus lipos and vinyl on the fuse.)

Engine power is (2) 2W-20 HET, 6904 EDF, 75A ESC, so I have power to spare- I understand 700W-800W per side with this set up on 4S 5000 lipos.

The question is: Do I go with one or two 4S 5000 lipos?? At basically 1.5 pounds each, I'll be pushing 10 pounds AUW for takeoff, but at the same time, I'll have a ton lot of power and flaps (spar has been beefed up to with carbon too).

Do I go with one lipo and take off at 8.5 pounds AUW <or> go with two lipos and rotate at 10lbs?

Two lipos or one?
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Old May 05, 2011, 01:41 AM
Go FASST or go home...
Ben_E's Avatar
Bergen, Norway
Joined Nov 2002
3,133 Posts
Quote:
Originally Posted by Doug W View Post
I recall Ben_E saying to stay out of the 9+ weight range...question for the group (opinion on added lipo weight v flying time).

I've got all this wonderful high lift stuff- flaps will add a ton of lift for sure, and thus far, I am in at 6.7 pounds (I am not fully assembled, but it is all on the scale, minus lipos and vinyl on the fuse.)

Engine power is (2) 2W-20 HET, 6904 EDF, 75A ESC, so I have power to spare- I understand 700W-800W per side with this set up on 4S 5000 lipos.

The question is: Do I go with one or two 4S 5000 lipos?? At basically 1.5 pounds each, I'll be pushing 10 pounds AUW for takeoff, but at the same time, I'll have a ton lot of power and flaps (spar has been beefed up to with carbon too).

Do I go with one lipo and take off at 8.5 pounds AUW <or> go with two lipos and rotate at 10lbs?

Two lipos or one?
Now that I have flown my plane some more, and got a better feeling of it itīs easier to give you a better answer to your question.

My planeīs AUW is 4,3kg or about 9,5 pounds. My power setup is about the same as yours. After the first of the 2 flights this weekend I set the timer on 3 minutes, flew with good throttle management (cruise at less than half throttle) I landet after about 4 minutes and had consumed 4600mAh of my total 8000...

My wings are not as strong as yours, since you have strengthen them with carbon. I have added glass fibre tape on the underside, but they flex quite a bit, also when rotating. Too bad I havenīt got the pictures yet, because you will see it quite well on rotation.
Because of the wing flexing, the ailerons effectiveness is somewhat reduced. Itīs quite sluggish to fly. Not difficult but, itīs definitely not crisp.

My recommendation is to do your maiden with one 5000mAh pack, set the timer for 3 minutes, take off at WOT, reduce power immediately after getting altitude and get the feel of the plane. Then trim it and land. Fly the plane a few flights to get used to it and the add the second pack for longer flights.

If your wings are stiffer than mine I think it will handle the weight without any problem. With flaps you should be able to fly slower on landing, though itīs already quite slow without so itīs a no issue.

My concern with your weight is the landing gear... It just does not hold up a plane in this weight range. The 3 mm pins has to be changed with something stiffer (stainless steel) or modded to 4mm. On my first landing, (which was quite good) they start bending, and when they do they are gone. On the second landing, not that soft they bent again. I also have problems getting the gear to be straight in line, resulting in a plane that sideslips when rolling on the ground

Hope this helps!

Ben_E
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Old May 05, 2011, 09:29 AM
Ugly planes do not fly
_Sergey_'s Avatar
USA, GA, Alpharetta
Joined Mar 2007
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Doug, I have to agree with Ben. 5Ah is lots of energy. You should be able to have 3-4 minutes flights with one battery. As Ben says, install one (check CG) and take off at full throttle. Get altitude gradually reducing power while trimming the plane. Get the feel of the plane and land in 2.5-3 minutes. Recharge the battery and check how many mAh is charged back. Knowing mAh and time you can tell exactly how long you can fly off one battery with spare for missed approach. I am comfortable flying my plane with one 4Ah. The maiden was done with two 2.2Ah and after 3 minutes plenty of capacity left.
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Old May 05, 2011, 10:27 AM
Screw the wind, let's fly!
Naval Warfare's Avatar
Lawrenceville, Ga
Joined Feb 2008
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Quote:
Originally Posted by _Sergey_ View Post
Doug, I have to agree with Ben. 5Ah is lots of energy. You should be able to have 3-4 minutes flights with one battery. As Ben says, install one (check CG) and take off at full throttle. Get altitude gradually reducing power while trimming the plane. Get the feel of the plane and land in 2.5-3 minutes. Recharge the battery and check how many mAh is charged back. Knowing mAh and time you can tell exactly how long you can fly off one battery with spare for missed approach. I am comfortable flying my plane with one 4Ah. The maiden was done with two 2.2Ah and after 3 minutes plenty of capacity left.
Yer battery mayve been fine, but you sure looked drained
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Old May 05, 2011, 05:06 PM
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scottd9990's Avatar
United States, NC, Charlotte
Joined Jun 2009
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drained

I resemble that remark!!!!! . Sitting in Atlanta Airport on way home
From LA.
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Old May 06, 2011, 03:14 AM
Go FASST or go home...
Ben_E's Avatar
Bergen, Norway
Joined Nov 2002
3,133 Posts
Anyone else flying their 737? or getting ready for maiden this weekend?

Ben_E
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Old May 06, 2011, 05:32 AM
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Tampa, FL
Joined Aug 2010
68 Posts
Projected maiden in 2 weeks.

Question for you running on 4S: How much runway are you using in take-off?

My flying field has fairly smooth 300ft runway...packed dirt covered by landscaping material. Will this be enough?

Power system will be Cyclone 3700kv with 2 x 3000mAh 4S. No added weight to the plane except Qantas paint/sticker scheme.

Thanks
ren
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Old May 06, 2011, 06:04 AM
Go FASST or go home...
Ben_E's Avatar
Bergen, Norway
Joined Nov 2002
3,133 Posts
Quote:
Originally Posted by Whodatbflyin View Post
Projected maiden in 2 weeks.

Question for you running on 4S: How much runway are you using in take-off?

My flying field has fairly smooth 300ft runway...packed dirt covered by landscaping material. Will this be enough?

Power system will be Cyclone 3700kv with 2 x 3000mAh 4S. No added weight to the plane except Qantas paint/sticker scheme.

Thanks
ren
I think you should have space enough, since you should have at least 2x600W of power.

Ben_E
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Old May 06, 2011, 09:17 AM
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Doug W's Avatar
United States, WA, Seattle
Joined Jul 2010
445 Posts
Quote:
Originally Posted by Ben_E View Post
Anyone else flying their 737? or getting ready for maiden this weekend?

Ben_E
I'm probably still 3 weeks until maiden.
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Old May 06, 2011, 09:29 AM
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Highfly!'s Avatar
United States, CA, Cameron Park
Joined May 2007
1,259 Posts
Still screwing around with landing gear doors for the nose retracts. I am also concerned with what others are experiencing with the main gear so I will have to make up my mind soon whether I have the existing retracts upgraded or just have it replaced with e-flite gears.

This weekend the fuselage should be covered and custom decals applied. Looking for a maiden within 2 weeks.
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Old May 07, 2011, 08:28 PM
Ugly planes do not fly
_Sergey_'s Avatar
USA, GA, Alpharetta
Joined Mar 2007
1,689 Posts
How to connect two ESC in parallel

Hi Doug, sorry for a delay. Here are pictures on what to do with ESCs to make them work in parallel and also disable their BECs.

You just remove red wire pin from each ESC's connector, connect them to Y splitter and plug to the throttle port on the Rx. That's it.
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Old May 08, 2011, 01:03 AM
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Doug W's Avatar
United States, WA, Seattle
Joined Jul 2010
445 Posts
Thanks Sergey!

Quote:
Originally Posted by _Sergey_ View Post
Hi Doug, sorry for a delay. Here are pictures on what to do with ESCs to make them work in parallel and also disable their BECs.

You just remove red wire pin from each ESC's connector, connect them to Y splitter and plug to the throttle port on the Rx. That's it.
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Old May 08, 2011, 01:05 AM
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Doug W's Avatar
United States, WA, Seattle
Joined Jul 2010
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Quote:
Originally Posted by Doug W View Post
Thanks Sergey!
Oh yeah, and gimme a second, I've got a video for the group...
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