RE: BME Edge?
 

Which pull-pull setup should I get?

Dubro makes one for .91 and up, SWB, Airwild?

Thanks.

RE: BME Edge?
 

Well I got mine, put it together in a few days and have flown it... here are my comments.

Home runs: looks, after recovering very nice looking plane and solid too.

Hits: Good construction, well laid out, quality materials, very cool that hinge points were already done.

Strike outs: "Chinakote" covering, WAY heavier than advertised, hard to balance, hardware, wheels and tail wheel are junk

Overall - I really like the plane because it looks very nice and I think it is going to fly as it should once I get the balance issues worked out. It flies well, but whomever said they got their plane to 16 pounds had to be on something when they weighed it. NO WAY.

BUYER BEWARE... if you are expecting this plane to be 1.5 pounds lighter than a WH you will be disappointed. I weigh all my planes on a 3 point strain gauge, not a fish scale, so my weights are accurate to a few grams.

I like to build my planes very light and will do some radical things like cutting and buy some pricey CF stuff if needed to get it to where I think it needs to be. There is no reason this plane should not have been able to get under 16 pounds with the equipment I had selected, but that is a PIPE DREAM due to the tail group being excessively heavy. The layout of this plane is such that everything lies ahead of the CG, so removing weight by using items like CF gear, spinner, etc or not using redundant batteries, etc only shifts the CG further AFT.

My plane came in at very disappointing 17.5 pounds and balances at 6.0 inches (a full 1 inch aft of the max 5" in the manual). You will see in the pics below that everything is as far forward as possible and the tank is on the CG.

Honestly, the best CG point appears to be 5.1" for 33% MAC, and others here have said 5.25" works best. That means 6.6 oz more noseweight to shift the CG. I can pick up 2.5oz by using the Bolly Prop and 2 oz more by ditching the CF spinner for a cheezy aluminum one like the Dave Brown Ultimate. Even doing that I will still have to add 2.5 oz of lead... BS

Total weight = 18.1 pounds. STINKS.

I am considering taking a hole saw to the elevator and rudder surfaces and drill out some of the tail gear plate to get some weight out of the tail.. I have done this on Cardens in the past and have had great luck but I don't know how well built these surfaces are or how much I will weaken them. I also really don't want to recover the tail ... AGAIN.

Flight: So far I have two flights - the maiden and one more test flight. With the CG at 6" (just forward of the wing tube) it definitely flies tail heavy. Inverted it pulls up, vertical bank the tail falls. It drops a wing on slow approaches, but is predictable like my CAP so I just land it a little hot.

The engine is new, so I did not get too crazy. TR's were simple, as one would expect them to be with a tail heavy plane. I have flown many planes with CG further back than suggested and had no issues. Unfortunately, with the weight of this plane at 17.5# and the CG at 6 inches, it is touchy enough that I won't fly again until I fix it. I can fly it like this, but who knows what it would do in a dead stick, wind gust, etc. It should fly better and that is that.

The controls were touchy enough and landings hairy enough to make it a no-fly situation until I get the CG right.

I am afraid the CG needs to be between 5 and 5.30 max and at 6.0 is too tail heavy.

I will post any new news / flight info when I finally figure out how I am going to fix it. in the mean time .. here are some pics!

DP

This group shows the engine box.
Notice the fiberglass and screws. I also tied the firewall to the next former using 8-32 all thread, a proven very strong method to keep firewall
from flexing. I do this on all ARFs.

All batteries, regs and switches are as far forward as possible and I fabricated a lightweight choke bellcrank to save the weight of a choke servo.

RE: BME Edge?
 

Here is another set... radio layout, fuel tank, and pull pull setup.

RE: BME Edge?
 

Here is the stripped covering, with some of the recover in process...

RE: BME Edge?
 

Here is the final, finished version as flown.... love the way it looks now if I can only get the CG up a little without piling on more weight..


DP

RE: BME Edge?
 

desertpig - Thanks for posting up those great shots. I can see a couple of things you can do to move the weight forward so you don't need to add weight.
1) The flight batts can go further ahead, they look nice sitting there all velcroed in and all, but they don't need to be sitting that far back.
2) Why is the throttle servo that far back in the fuse? I would think a shorter, stiffer linkage would be more desirable that a long rod in a Sullivan sleeve.
3) I know the rudder pull-pull is done, but that servo can probably be moved ahead 2 inches. It looks like your mounting rails are made to be moved?

My setup is going to be very similar. I was thinking of ditching that tailwheel assy right from the get go.
Don't know when mine will arrive, but I hope mine can be finished at no more than 17lbs tops. I will be dissappointed if it gets heavier.

BTW, nice job on the re-finishing scheme.

Spar

RE: BME Edge?
 

Desert Pig,

First off... excellent work, meticulaous building and a great modded scheme... looks like it was designed that way.

Looking at your pics I do, however, see where some weight savings and balance issues could be adjusted.

Unfortunately it may be too late for you to do some orf them (or too much work).

I ALWAY assume a plane is going to be tailheavy and build accordingly. It's always much easier to balance a plane that's been built this way.

Here are some other helpful ideas...

Space the engine out as far as possible... this will mean moving the side cowl mount locations in front of the former and will rest the top of the cowl just lipping over that former and onto the hatch maybe 1/16"... this will move the engine forward 1/2" Might fudge an extra 1/8" of space between the cowl and spinner too. You can still do this... a little work... just add 1/2" blocks (or whatever you can squeeze) under the standoffs... then if you extend the cowl mount blocks and drill your existing cowl hoels into them you won't have to redrill hole in the cowl... just cover the 4 holes in the fuse where it used to attach.

I will be putting my ignition in front of the firewall along with the battery and regulator. This not only will help with their wieght forward of CG, but allow you to place other things close to the front of the plane as well. Might even build a "tounge plate" to push them out another couple inches. you can easily do this.

I won't be using redundant batteries, switches on a plane this size. You've added 1/4 lb. there.

Place the tank back up in the nose... instead of on CG.

And here's the single most tailweight savings... place the rudder servo where the throttle servo is... throttle servo more forward... perhaps just in front of the F1.

Can't see if that's a CF tailwheel, but that's what I'm going to use... definitely the stock tailwheel is too heavy (but not junk). That stock wheels I LOVE infact I ordered several pairs at several sizes due to their extreme lightweight... VERY dense foam that will seem to resist flattening but SEVERAL oz less than Dubro Treaded LiteWheels. If you used Dubro or Sullivan you added 2 oz plus...


To be honest... I can easily see where you might have picked up an extra pound in building and caused some nose weight to be needed. And an ARF can easily vary by 1/4 in wood density and glue/paint variance.

As I said, I'm not knocking your work... it's excellent... but you have made concessions with moving the tank back, using dual batteries/switches, replacing the tires, etc...

I had problems balancing the WH Edge too and that was with a 3/4 lb smoke system a good bit ahead of CG...

I think maybe both manufacturers moved the wing back 1"-1.5" in a future revision, there would be much less concern...

RE: BME Edge?
 

Maudib, Sparhawk - thanks for the feedback.... I am with you - I always build assuming the plane would be tail heavy, but I was not prepared for how tail heavy this one was going to be....
This is in fact the first plane I have ever had problems balancing and I have built / set up a lot of planes. My guess is someone was real heavy on the glue in the tail.

I agree the engine could have been spaced out a little more, but the pathetic manual did not include a firewall - to- thrust plate measurement so I set it for its max and adjusted the cowl accordingly. I could have moved the engine maybe 3/8 further forward using block spacers, but that increases vibration on the DA. It would be like adding 4 oz of weight to the moment though. I looked on all the posts before I set mine, but did not find the suggested 6 7/8 until AFTER I was done... [:@]

I don't like ignition modules in the cowl, there is a lot of heat and vibration with little airflow at the firewall, but I might have no choice here. I also like to keep my flight electronics further away from my ignition than it is now, but again, in this plane I am already within 4 inches, moving the ignition to the firewall should help.

The throttle servo is a 1oz mega mini, I had no room to move it forward due to the batteries in the way... it will make no diff where it is as long as its forward of CG. Moving it 2" more forward would only change the moment weight by 0.25 oz.. .not worth the trouble.

On all my planes I put the tank over CG, moving it forward will throw off trims during flight as the fuel load changes.. not good for running IMAC patterns.. in fact there is nothing worse than starting off with a nose heavy plane that handles better as fuel load gets lighter... but that's me. I actually have not seen any gas planes built with the tanks forward... I just remember the pain of the glow days nose heavy on take off..balanced on landing....

I used an Ohio Superstar medium tailwheel (2oz total wt) the Graphtech small tailwheel is 2.2oz, so its actually heavier and is not as strong

I know there is a debate about redundant batteries, etc. I chose Li-Ion, and one 2200 mah pack won't supply enough current to 5 hi torque digitals under a large 3D load. To satisfy my load requirements I needed a 4400 Mah Li-Ion or go to NiCad or NiMH , so I chose 2 redundant packs instead of 1 larger pack. My total weight with two packs is about the same as one 2400 Mah Ni-Mh and one superswitch.


About the wheels... I agree with you that the LOOKED very nice and were lightweight. I have several people here on RCU PM me letting me know they fall apart rather quickly especially if you run them on pavement or gravel (both plentiful here in the desert).. I had a wheel break on me once on a 40% bird... almost lost it on landing when it ground looped.. somehow I was able to give power and rudder to steer it away from the fence .. won't be taking that chance again. I never use the wheels that come with the planes.. I have had issues 100% of the time that I have...


I have the bird on the bench now. Since everything is velcro'd its easy to move things around... I doubt I will have to move too much to get it where it needs to be... shouldn't have to do it... but ...
I'll let you know how I made out..

DP

RE: BME Edge?
 

Ooopsss you've been misinformed....

the Graphtec tailwheel is .9 oz their 40% tailwheel is 2.2 oz.... :)

So you'd save an oz in the tail and what... maybe 3 or 4 in the nose? A quarter lb there alone...

The wheel get ate up on concrete huh? Wish these guys would be a bit more open instead of sending people PM's... I fly off grass and it's a non-issue even if they do... for me the are the sweetest tires available on the planet... :) Heck... for the weght savings, it would be worth buying a half dozen pair to replace when they get worn.

I agree with the tank on CG, BUT it's rarely designed that way by the manufacturer, and in this instance would put another 1 or more oz in the nose.

You didn't mention the rudder servo placement... again... likely to help alot on balance. I'm going to try and mount mine in front of the wing tube... perhaps as far foward as where your throttle servo... letting help the CG not hurt. Pushing the batteries to the side and vertical would open a lot of room for location the servos.

Between this and the tailwheel I think you could get your CG up to where you wanted it... especially if you move the ignition/battery to the front of the firewall...


Whle I know most of my suggestions were minor... they all add up... an oz here and an oz here add up quickly, especailly when electives like an extra 2 oz from batteries/switches, 2 oz in heavier wheels, 1/2 oz in the firewall reinforcement, 1/2 oz in the choke bellcrank setup.

Elections like placing the ignition & battery behind the firewall, tank on cg and it's related extra weight to get it mounted there, etc.... all play as to whether a plane that's hard to balance becomes impossible or not.

There's not that many 50x cc plabes out there just yet, and so far we're finding a good bit of them to be tailheavy... scale and the level of building strength needed to go from glow to gas may be making it harder.

So my thoughts are offered to help reduce weight and balance more conservatively.

I don't think think the BME is a poorly designed aircraft due to it's balance issues... nor do I believe it's impossible to balance. but it is good that you have shared these pics and your choices so that others can be aware of just how critical placement of engine & equipment and assembly of this particular airframe is in reference to acheiving balance.

I'm still hoping for 16 lbs... maybe that's crazy... I really wanted the 15.5 but even I can't seem to see it getting there... we'll see... but not til spring...

RE: BME Edge?
 

I'm in the process of moving stuff around now... I moved the ignition to the firewall, doubled up the batteries and mounted them on the other side inside firewall. Ditched some of the hardware and velcro.

BTW.. The graphtech website is a bit overly optimistic.... Yes, the gear leaf weighs .9 oz, but when you add the springs, screws and wheel, the weight is up to 1.88 oz.. That is exactly the same weight as the Ohio Superstar medium set.

The graphtech small gear set is very fragile, I broke it on my 1/4 scale cap and I am a very gentle lander. I won't use it again. On a plane this size I think it looks too small as well. Actually, the gear that came with it is about right, but it weighs 3.2 oz... way too heavy that far back..

The Graphtech medium gear is just right for this plane, has the correct scale, and with the supplied wheel and two springs weighs in at 2.66 oz I was going to switch the CF gear off my CA 31% because I thought it would be lighter.. its not.. so I stuck with the Ohio gear.. its very strong for its size.


Anyway, the advertised weights on a lot of stuff is not where it usually comes in at.. and I am used to that... its why I try to jam everything forward if possible. The layout of this plane does not make it real easy once the tank is in place unless, like you said mount the tank forward of CG.. I just can't bring myself to do that... I could go to a smaller tank too, that might give me some more room, but I like having the extra gas as sometimes I repeat patterns and lose track of time during practice...


It looks like I am going to be on a CG of 5.25" at 17.4 pounds ... respectable but no 3D monster.
I am hoping the Aerotech Velox I have on order will prove a lighter build.


I am sure this plane can be built lighter than I have built it. If I had it to do over here is what I would do:


1> Space engine off the firewall 7 inches or just enough to leave a 1/16" overlap over the second former, mount all ignition components on the firewall
2> Can the DuBro HD hardware.. its too heavy.. I'd go to Rocket City horns instead (nelson) I am sure that would be good for at least 1.5 ounce in the tail all that DuBro stuff is 10-32
3> Mount the rudder pull-pull as far forward as possible... like almost under the wing tube!
4> Mount a 20 oz squatty square tank, so that it will fit in front of the wing tube and still be very close to being on CG
5> Get out the dremel and get rid of some of wood around the butt end of the tail. It is way dense and thick... no need for all the wood there as it only holds the tail gear
6> Hole Saw several lightening holes in the elevators and rudder and recover
7> Install a CF wing tube and main gear, this alone should shave 7 oz +


I have already done the following:
CF Spinner
MenzS lightweight wood prop
Mini Digi on throttle
CF pushrods w/titanium ends on elevators
UltraLite main gear wheels
Ohio Superstar Lightweight tail gear assy

Unfortunately, without the first 7 items done, my efforts were wasted. It would be too much time and materials to rework the rudder pull pull and tank areas, so I have decided to settle on a 17.4 pound airplane that balances with everything jammed foward...

DP

RE: BME Edge?
 

DP glad you got it balanced. I think you will forget about the weight when you fly it with the correct cg. It really is a nice flying plane.

RE: BME Edge?
 

Thanks Eric... I absolutely love the way it looks and even when it was tail heavy it still flew pretty light... so I think you're right... I will like it...
I don't like to sound like I am whining about weight.. but the plane definitely is heavier than it needs to be out of the box... oh well... I'll shut up now and just enjoy it!!

Thanks for the pics and your setup info!! Everyone else too!!
As soon as the monsoon clears out of here (2" of rain in the desert in the past week...) I'll let you know how she flies !



DP

RE: BME Edge?
 

Well, I just received my BME Edge. The kit looks great! Initially, I tried to decide between some of the 28% ARF offerings that are available. I wanted an Edge because of the straight leading edge. The reports in this thread sounded positive. Since I wasn't crazy about scheme on the WH 28% Edge, I went with the BME Edge which looked more acceptable. I ordered right before DesertPig's new posts about the balance issues. In hindsight, I probably should have gone with the better known WH product. When it comes to ARF's you just don't know what you're getting, so a proven product shouldn't come up with new surprises.

Thanks to DP and everyone's suggestions, it sounds like I can work around the balance issue. I believe it's been noted that the engine firewall needs beefing up. DP's bolt at the top two formers looks like a good option. I have a BME 50 and it looks like I can mount it so the prop hub is 7" in front of the firewall.

A couple of questions, in earlier posts it was suggested to get the 3 degree offset on the firewall, you would move the right side 5mm. Since the firewall is 9 inches, I drew this out on a piece of paper with a protractor and it appears to be more like 10mm. I know my math skills aren't the greatest, so can anyone confirm this?

Also, is everyone using BME's suggested wing tube attachment method? Is it possible to use a bolt from inside the fuselage (similar to the Funtana 90 and others).

Thanks in advance.

RE: BME Edge?
 

ed -

I mounted the firewall FLAT with no thrust.. I then used washers and countersunk the standoffs to achieve the right amount of thrust... 3* is too much... 2* not enough. Its easier to be able to change the standoffs than it is to
change the firewall IMO.. also the reinforcement bolt won't line up as nice and a square box makes for a stronger firewall...

As far as the wing tube - bolt it in per the manual... it is a royal PITA to align if its loose!

You might also want to change the wing mounts... instead of simply tapping holes in the wing tube and using the supplied screws.. I ditched that setup. Instead, I used the wing tube to core some 1" thick soft balsa to make "end plugs" I then drilled 1/2" holes in the end plugs and glued in 1/2" round dowel hard points. I inserted and glued the plugs into the wing tube (after I drilled the holes in the tube from under the wing) then drilled the holes in the plugs through the existing holes in the wing tube... I tapped the holes with 8-32 threads and used a DuBro socket head screw to secure... rock solid.


PM if you need any suggestions... wish I had a virgin kit to start over on!!

DP

RE: BME Edge?
 

DP,

Thanks for your suggestion on the wing retentions mods. It certainly sounds better than just tapping into the wing tube from underneath the wing.

I was wondering if anyone tried to bolt thru the fuse side into the wing cord. Similar to this:

[link=http://www.rrcc.org/reviews/awedge540t/aw540t10.html]Wing Retention[/link]

Ed

RE: BME Edge?
 

Ed,

You could easily do that mod to this plane... What you need to make sure of is that the wing tube itself stays centered in the fuse... it's possible that the wingtube might slide further into one wing and perhaps enough that the opposite wing doesn't have sufficient support... I haven't checked mine yet...

Just check to make sure this isn't the case (it was with the lighter Wild Hare tubes).

Center the tube in the fuse and mark both sides... labeling them left and right... then remove the tube and stuff it in each wing half checking to see if it slides significantly further in on either side.... if there seems to be too much (maybe more than a 1/2" or so) then you can shorten the wing tube socket by taking a thick cardboard tube that's a little bigger than the socket, cutting it to length, then cutting a sliver from the circle making a "C"... pinch it together and insert in the wing socket and stuff it down with the wing tube.

RE: BME Edge?
 

I did that exact thing on my CA31%... I left the Edge alone as I my method using the wing tube mentioned above really worked well.. that and there was very little room to manuever around inside the Edge to be messing around with bolts inside the fuse...

DA makes some really nice anti-rotation / wing retainers... I will be using them on my next large project...

DP

RE: BME Edge?
 

hey guys, i just got a BME 30% Edge 540 on Christmas day(lucky me!!).. anyway, i have it all ready to fly less the engine. im going with a G-62. and hear this, the plane weighs only nine point zero seven(9.07) pounds without the engine!! so im gonna have a 14 pound plane with a G62 in it!!!!![8D][8D]:D:D

RE: BME Edge?
 

Well, you won't have a balance issue will ya... :)

RE: BME Edge?
 

Dont forget to put the wings on.

;)
Just kidding.

How so light? What servos and components are you using?


Congrats on the weight.

Rob

RE: BME Edge?
 

He's a troll... either that or he has HS-81's all around... ;)

RE: BME Edge?
 

heres what i have ON THE PLANE NOW..
Setup:
Engine- none
Servos- (4)Hitec 645's (1)JR 8611 (1)Fut 3004
Linkages- All CF with titanium ends (4 rods and 8 ends)
Expert and Cermark leads and reversers
Futaba 149DF reciever (PPM)
Both wings:D
all control surfaces(duh)[&:]
canopy hatch
Du-Bro 4-40 Pull-pull system
robart control horns
hangar 9 servo arms (4)1 inch singles (1)2 1/2 inch double
Du-Bro ball-swivell links(8)
all decals
and thats pretty much it.. o yeah, a two bottles of epoxy:D
all up weight(i weighed it a second time 2 minutes ago nine point zero six (9.06) pounds.. so we lost 1 tenth of a pound..shes been watching her carbs!:D

RE: BME Edge?
 

actually, i have metal geared servos!! i guess this balsa and ply was very light in this kit.. but im not complaining! i can't believe it came out to 9 pounds.. thats just magic fro 85" of wood. and this is built really strong!
BTW.. my original choice of engine was a Moki 2.10.. so even with that engine.. it would've been 12.5 pounds!
O.K. that's my shpiel.

RE: BME Edge?
 

First you forgot batteries...

Second, it's possible that your bare plane weighs 9.06 lbs... but even that would be a stretch...

My fuse, wings, wingtube, cowl, canopy, hatch, pants and stabs that are hinged, 2 Dubro HD control horns and a Dubro pull-pull horn all weigh right at 10 lbs...

That's no servos, no batteries, no receiver, no linkage, no wheels, no extensions...

Simply NO way yours weighs 9.06... but you can keep on thinking that if it gets you through the night... :)

RE: BME Edge?
 

i guess i did forget the battery, but it was too in the plane when i cheked it, a JR Extra 1800 Mah pack.. and ill send you a pic tomorow of the scale and how much it reads! i'm tellin ya, it weighs 9 pounds!!! i just triple checked it!