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Mission Impossible? Putting a pattern plane on a diet?

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Old 08-23-2008, 03:54 PM
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Mastertech
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Default Mission Impossible? Putting a pattern plane on a diet?

I've been looking for an accurate scale to measure my airplanes and parts for sometime now. I'd been using a scale that would only go to 5 pounds in 1/4 oz increments. I looked on line and shopped the local area and finally settled on a 20 pound scale that would measure in 1/10th ounces. I found what I wanted at the local Staples.

So seeing is I have a new toy to play with I go to the mancave and set up to weigh my current plane.

The Object of my Affection.

[img][/img]


I set her cradle up on the scale and hit the "Tare" button to get back to zero.

I then placed my Proline in the cradle.

[img][/img]

And took a reading...........................

[img][/img]


YIKES !!!!!!!!!!!!!!!

IT'S OVER WEIGHT !!!!!!!!!!!!!

Oh what to do what to do??????????????????????

I knew there was nothing much to be done with the wing so I removed it and set it aside and reweighed the airplane.

[img][/img]


Ok, first thing to do was to remove the dead weight I'd installed playing with the trimming.

[img][/img]

That 3.1 oz of lead nearly got us under the limit.


Looking further,

[img][/img]

Dave Brown from Sullivan wheels same size.

[img][/img]

Even more,,,,,

[img][/img]


JR 1221 to a JR 921 Reciever

[img][/img]

Even more weight savings.

Removed the remote glow, I still like this unit as it gets my arm away from that 18" prop. If the weight goes down far enough this will go back on.

[img][/img]


When I built this airplane I had on hand a new 2300 5 cell nicad battery pack. What I didn't realise was I had installed this heavy weight into this airplane.

[img][/img]

Kind of heavy wouldn't you say?

Here's a 2100 Nihm 4 cell pack.

[img][/img]

I'm not going to use this pack as I'll probably go to a Li-Ion pack that weighs 3.9 oz. I'm going to assume at this point the regulator weighs one ounce giving me a net savings of about 2 oz.


Here's the problem, All of the weight I've removed so far has been in front of the CG where I need the weight. To get to the 170mm CG recommended by Akiba I need to add back the 6 oz of weight.

So after talking to a few guys I've decided to use a hopper tank at the firewall. I weighed 8oz of fuel and it is about 7.5 oz. So adding a tank that weighs 1 oz and the fuel it'll get back to where I need it.

to be continued.................................

Please feel free to add your own weight saving idea's.
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Old 08-23-2008, 05:58 PM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

I'm looking at the same aircraft, so this was no good news....
The CArf Impact also had a tendency to hit the wrong side of the scale. One trick I heard was to rebuild the rudder.
One drastic thing to do is of course to make new wings, stab and rudder, but that might be too much work..? Is this the all composite Extreme Comp. version?
Do you have pics of the interiour?

Weight saving options:
Light back plate on spinner (maybe even look for a CF Spinner?).
Single servo on elevator control w/pull-pull and MK belcrank
Carbon pushrods / Kevlar pull-pull system
Honeycomb/CP sandwich servo tray/tank foundation
Carbon canopy (and cut away unneccesary cocpit decking) http://home.online.no/~ofremmi/HowTo..._and_epoxy.htm

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Old 08-23-2008, 07:15 PM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

Thinn

This airplane was built by me with ZERO attention to weight. When I built the airplane it weighed 10 pounds 8-10 ounces, as best I could measure it anyway. Through the last year I've made additions and changes to the airplane and some minor repairs which led to the over weight condition. I used what I had on hand during the build, If you look at the materials I used everything is wrong. The battery is about 3 oz heavier than really needed (2200 5 cell Nicad). Somewhere along the line I changed the battery and picked up the wrong one. The lead I added during the trimming process was just to test. Those two items are nearly 1/2 a pound!

This airplane will be around 10-10, when I've gotten the diet completed, with currently used materials in the pattern world. The reason it's over weight at this point is all mine and not the air frame. I got it under max weight easily by changing a few items. If I wanted to take it to the extreme (Like the electric guys do) I could probably reduce the airframe another 1/2 pound. I doubt I'll bother going to that extreme. My target weight right now is 10-10 to 10-12.

Beyond that I don't really care.

This is an exercise in weight reduction. I've never paid attention to weight before, I just built and flew them.

I started with the big items and am working towards the small items. Why look for a few grams when you have full ounces you can just reach in and take out.

As far as cables and bell cranks for elevators I'll never use those again, I'll never use twin servo's in the tail again either.
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Old 08-23-2008, 09:44 PM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

Changing to the DEPS system will allow you get some weight out of the tail. It can be installed after the airframe is built as well. Go look at the ZEQUE thread from about two years ago. Troy installed one with the plane already built. Was actually pretty easy. I was there when he did it and it was done in the course of one evening.

Arch
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Old 08-23-2008, 10:30 PM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

I'm actually writing up something for the K-Factor right now about how I dropped my Nats bird from 11lbs 7.6ozs down to 10lbs 13ozs in 3 days....[sm=eek.gif] I hope someone will benefit from it.....
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Old 08-23-2008, 10:53 PM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

Hi Arch

I'm considerng that as well. My second Proline has twin servo's in the stab and they never stay the same. A set of servo pots in the first 30 flights doesn't bode well for that setup.. The Deps will take care of that. I'll look in that thread. Thanks
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Old 08-23-2008, 11:49 PM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

Ya before Nats My plane was about the almost same weight as Jeremy's. 11lb 5oz was mine. but Mike "the Magician"Hester was able to get rid of that 5 extra oz and then some
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Old 08-24-2008, 12:59 AM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

When you guys talk about weight limits and weighing a plane, is it flight ready, everything installed, but no fuel? I always thought people weighed the planes before the engine was put in, but I'm now assuming that's wrong.
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Old 08-24-2008, 01:59 AM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

Yes, the rule is 5kg ready to fly no fuel. Unfortunately for electric guys, full and empty weigh the same. Now fortunately for the electric guys, they can build lighter because the airframe doesn't have to stand up to the vibrations of a glow engine.
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Old 08-24-2008, 01:11 PM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

Hey Tim,

I just went through the Partner to get it under weight.

1. Had to change out the Duralite 2800 pack to a Thunderpower 1100 Lipoly pack it only weighs 2.0 OZ can easily get 5-6 flights.
2. Changed the wheels, yours look ok,..I went smaller.
3. Changed the tail wheel,..even smaller.
4. Went to smaller hardware,..wheel colars, etc.
5. Changed to micro/mini servo for throttle.
6. Went to a plastic spinner with a light back plate,..took the trueturn off.
7. Went to mini servos in the tail.
8. Changed all of my servos out to a compairable servos with less weight.
9. Smaller switch.
10. Cut small cut outs in the stab root rib,..cored out some foam and put a balsa plug in the cored area,..keep fuel out.

Went out of my comfort zone here,..seems to be just fine.

A dear good friend and mentor of mine and ours explained his philosophy of weight to me years ago. He said "If you take a pound of sugar, pour it out, spread it around you still have a pound of sugar,...so find ways to brush small amounts from the scale,..every grain no matter how small is weight loss",............end quote:Kirk Gray,..rest his soul.


The Partner needed some repair and paint when I recieved it,....it was over 11 pounds,..now it's 10lbs 10 OZ as of yestarday,...

If anyone on the post knows where the incidence of the wings should be set,..I'd be grateful for some info.

Anyway,..good luck Tim,..lets fly!

Bill Holsten
Dist2
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Old 08-24-2008, 05:34 PM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

You going up to Bill Mitchell's contest? I plan on going up Friday morning.

My Proline is under weight. Just changing the battery and removing the lead in the nose did that. I took almost 1/2 a pound off it with just those two things. I just came in from flying and I can tell the nose weight is gone. I had to add a few percent to the mixes and all is well again. The airplane still flies much better than I can guide it.

When you flew it, it weighed 10-10 and you noticed the slight push to the gear with rudder input, I've been playing around with it awhile now and never really knew how much weight I'd added to it.

I've been playing around with Byran Herbet's triangle trimming method and I can tell you he's 100% correct. During this process is where most of that extra weight came from. I was doing it the easy way by just adding dead weight to the nose.

I think by adding the header tank I can get all the mixes out of the airplane. Do I need to? Not really, I just see it as a challenge.

I still struggle with the wings level push/pull thingy too much at this point to worry about a slight push to the belly. In Advance we're not in knife edge enough to really worry about it IMHO. At some point you have to stop trimming and just fly the airplane.

Given the fact most pattern planes tend to come out tail heavy I wonder why the designers don't just move the wing back .5"-.75". I know that was the hot tip on the Eclipse. I've seen it done on a Genisis and a few others. Works well.

Tim
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Old 08-24-2008, 11:29 PM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

Ah, see that! Now we don't need to get rid of the 5Kg weight rule! LOL

Yup, that's how you do it - save 1/4 ounce 4 times and you've just taken a whole ounce off the plane. Easy.

You guys are using HUGE batteries. I fly my glow setups with two 730 mAh 2S LiPOs (dual regulator redundant system). If you figure worst case on a glow setup using 175mAh per flight (sequence) you can comfortably fly 4 rounds without re-charging. I only use about 100mAh for 2 Advanced sequences in practice.

Never, ever, under any circumstances add weight to your airplane!!! Ever! Get the point? If you need to "adjust" the CG, do so by moving components. The only time adding weight is acceptable is when it increases strength. Lead stick-on weights do not do that. You CAN use them temporarily while you're trimming but once you're satisfied with the feel, move stuff around to get the same CG as you had with the weights.

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Team Black Magic

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Old 08-25-2008, 07:23 AM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

Yes,...I will be attending the Winston-Salem contest,..I missed the first one this year. I have actually been practicing quite a bit lately and that's mostly trimming and moving weight around,..no mixing yet except for Throttle to elevator. I have concentrated mostly on the "F' program with a spotter/coach and it's working out well,..the "P" is working out good,..we'll see?

Glad you worked out the woe's on the Prolines. See you in Wiston!

Bill Holsten
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Old 08-25-2008, 11:18 PM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

Tim,
If you're looking for some really light wheels, give these a try:
http://www.hobby-lobby.com/wheels.htm
The Dave Brown wheels are OK, but they tend to go flat. The "LYT" ones from Hobby Lobby are much stiffer. I have a few sets that are over 2 years old - still going strong. I DO glue the tires to the wheels with Zap-A-Dap-A-Goo however.

Whatever happened to your "Notes to Self"? That was good stuff!

John Pavlick
Team Black Magic
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Old 08-26-2008, 06:58 AM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

Yes the Dave Browns do flatten, I normally store my planes on a rack but sometimes they stay in the trailer. I've found that if I remove the wheels and let them set a few days they return to near normal.

I've been working on a few more installments with OFB. Stay tuned for the next episode.
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Old 08-26-2008, 08:56 AM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

That's one heck of a man cave Tim [8D]

As Chris mentioned I had to shave some weight from his plane before the nats as well. It was the first full tilt 2 meter wood plane that his dad had ever painted and rigged, and he did a fantastic job. However without the experience, it left them a bit heavy. I went through and examined the plane and found that the only place I could remove more than an ouce was by changing the battery pack, and we needed 7-8 to be comfortable.

If you want to save weight on a large 2 meter plane, Bryan Hebert put it best a long time ago...get used to thinking in grams. because 28 grams make an ounce, and you have to take 4 here, 8 there, etc.

Example: Servo screws. they are tiny, how much could they weigh? Individually, not much. But how many of them are on a plane? 20? more? If you go to s maller size screw you may ony save 1 gram per screw, but multiplied by 24 or so, that's almost an ounce right there. Rudder cable rigging....linkages....control horns...trim every screw, downsize every nut. Every last one. get rid of those steel axles and wheel collars, that alone is 1.5 ounces heavier than central's aluminum jobs.

Look closely at everything. Could it be lighter? Usually yes. Not by much....so you have to get aggressive. the best way to accomplish this is when you originally build the plane, approach it like you know it's going to be 15 lbs and you're taking care of it up front. if you approach the entire plane this way, it's much more likely to be under the limit to begin with.

When it comes to balance, follow these simple rules:

1. remove weight
2. move weight
3. try #1 again
4. try #2 again
5. make certain #1 or #2 are out of the question
6. add weight

And when all else fails, especially if you're tail heavy, make a lighter rudder or set of stabs.

The scale is your pal...make friends with it early. it's your personal double naught spy, complete with iron hat. It will tell you everything you need to know, every step of the way. The biggest mistake is never using it until after you're ready to fly. by then it's too late.

Tim your header tank trick reminds me of something Nascar would do LOL but hey, I'm guilty of that one too. It's legal!

have fun...
-Mike
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Old 08-26-2008, 09:21 AM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?


ORIGINAL: jrpav1

Tim,
If you're looking for some really light wheels, give these a try:
http://www.hobby-lobby.com/wheels.htm
The Dave Brown wheels are OK, but they tend to go flat. The "LYT" ones from Hobby Lobby are much stiffer. I have a few sets that are over 2 years old - still going strong. I DO glue the tires to the wheels with Zap-A-Dap-A-Goo however.

Whatever happened to your "Notes to Self"? That was good stuff!

John Pavlick
Team Black Magic
Actually the Dubro Super Lites are the best way to go to save weight. Tried the HL LYT and find these better all around
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Old 08-27-2008, 12:45 AM
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Default RE: Mission Impossible? Putting a pattern plane on a diet?

Hi

I know that this questions also comes up a lot when dealing with electric plane setups. After assembling a few OXAI electric planes I found the general rule to be that if the dry weight of the plane (Fuselage, canopy, wings, stab, rudder,landing gear and spats) is more than 2350 grams before equipment is installed you will not make the weight limited without special attention.

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