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05-01-2003, 09:53 AM
#51
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Heh. . . now THAT is funny.
K_Hunt, a lot of people have a terrible misconception about an engines strength, or lack thereof.
Billet machined aluminum cases, such as those on DA engines and BME's are substantially stronger for the amount of metal in the casing compared to casting such as 3W's and ZDZ's. The metal is a better alloy, machined to much closer tolerances, and resists impact damage and breakage much better due to a lack of porosity.
Prop strikes are funny things. . I've bent 2 3W crankshafts and a DA150 crankshaft in low-rpm (under3000) prop strikes, bad enough that one of the 3W cranks had to be replaced and the other two requred straightening out the threaded stud on the front of the crank to get the alignment proper again. All three require new prop alignment nuts/pieces.
Conversely, I've had a few prop strikes with BME's. . never bent anything even though I've sheared off wooden props (hey stuff happens!!). The "Grand Poobah" of proof, however, is that I once lost elevator controls on a 38% 260 powered by a BME102 (early version). The plane came down through a 125' pine tree, and scattered debris for 200 yards. I had bark and wood imbedded in cylinder fins on the motor, the headers were bent, canisters ripped apart and both arms were ripped off the shafts on the carburetor. Needless to say the Tru Turn spinner did not survive. I took the motor home, cleaned it up, swapped on a carb from another BME, bolted it to a test stand with a new prop and standard mufflers, and ran it.. it was like the motor was never in a crash. Even the bell mount on the back survived unscathed. Total damage was one broken and one cracked cooling fin and the carburetor damage.
The point here being. . you can take the most robust and overly engineered powerplant on the planet and bend the crank with a prop strike. . . or you can send it's lightweight competition through a tree at 60 mph and it lives to fly again.
If you build the plane to survive a crash, it will never get off the ground!! By the same token, if you build an engine to withstand massive abuse it was never meant to go through, it will be too heavy for its intended purpose. To steal a quote from Willy Messerschmidt, about the ME-109 fighter from WW2. . "The plane was meant to FLY. . NOT to roll around on the ground. . "
K_Hunt, a lot of people have a terrible misconception about an engines strength, or lack thereof.
Billet machined aluminum cases, such as those on DA engines and BME's are substantially stronger for the amount of metal in the casing compared to casting such as 3W's and ZDZ's. The metal is a better alloy, machined to much closer tolerances, and resists impact damage and breakage much better due to a lack of porosity.
Prop strikes are funny things. . I've bent 2 3W crankshafts and a DA150 crankshaft in low-rpm (under3000) prop strikes, bad enough that one of the 3W cranks had to be replaced and the other two requred straightening out the threaded stud on the front of the crank to get the alignment proper again. All three require new prop alignment nuts/pieces.
Conversely, I've had a few prop strikes with BME's. . never bent anything even though I've sheared off wooden props (hey stuff happens!!). The "Grand Poobah" of proof, however, is that I once lost elevator controls on a 38% 260 powered by a BME102 (early version). The plane came down through a 125' pine tree, and scattered debris for 200 yards. I had bark and wood imbedded in cylinder fins on the motor, the headers were bent, canisters ripped apart and both arms were ripped off the shafts on the carburetor. Needless to say the Tru Turn spinner did not survive. I took the motor home, cleaned it up, swapped on a carb from another BME, bolted it to a test stand with a new prop and standard mufflers, and ran it.. it was like the motor was never in a crash. Even the bell mount on the back survived unscathed. Total damage was one broken and one cracked cooling fin and the carburetor damage.
The point here being. . you can take the most robust and overly engineered powerplant on the planet and bend the crank with a prop strike. . . or you can send it's lightweight competition through a tree at 60 mph and it lives to fly again.
If you build the plane to survive a crash, it will never get off the ground!! By the same token, if you build an engine to withstand massive abuse it was never meant to go through, it will be too heavy for its intended purpose. To steal a quote from Willy Messerschmidt, about the ME-109 fighter from WW2. . "The plane was meant to FLY. . NOT to roll around on the ground. . "
05-01-2003, 10:01 AM
#52
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Shill. . we better watch out. . at this rate "we'uns mekaniks is gonna take over dis hyeah hoby!"
Dem dad-blamed injunirs caint make NUTTIN raht duh fust tiem!!!
Dem dad-blamed injunirs caint make NUTTIN raht duh fust tiem!!!
05-01-2003, 01:04 PM
#53
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Without pointing fingers - The facts of singles vs twins and how the dynamic and static weights and weight distributions compare -- is no secret to me .
The design differences are pretty straightforward.
The reason I like singles --is that they are --to be blunt -- simple .
Simple to use and setup .
I have done lots of complex stuff- and frankly not very keen on it now gear drives - belt drives on multiple engines - etc., and I do have twins - which are great engines -I am doing a new plane now for a 160 twin -and a 210 twin and just setup a model for a customer with a DA100 twin -
These rotary valve 40/60/80 ZDZ singles tho, -really impress me -
As size goes up - the inertia from unbalance goes up - - I do understand that.
I also like small displacement 4 stroke glo singles -but above a certain size/ poweroutput - they are just too shaky.
The 80 is still an accectable size for a two stroke single and even with a pipe - still costs far less than any decent 100 twin -
Powerwise - this setup is comparable AND the ZDZ single and pipe is lighter - (than twin 100 cc engines I actually use)
I get no damage from the low end (3000rpm) out of balance period and the idle can be sorted out easily.
As for "stock muffler comparison ".
The so called stock in cowl devices are all aftermarket -for ZDZ engines
Carbs ?- the retrofits I have done were simply to put on stock Walbro carbs - and ZDZ now uses these.
comparisons -brand to brand are typically not really apples to apples.
What is a good exhaust for one engine is a looser on another - even within same brands.
One "100 " is less than and another 100 is more than 100 cc
yet no one rambles on about that.
A pipe on a ZDZ 80,setup right, gives a huge boost - yet retains smooth transition.
you can add pipes to some other brands and get only moderate boosts.and sometimes lousy transitions.
If I need to do a 100 twin -with small in cowl mufflers - I would --and I do use the DA100 twins -
As Dave Johnson notes " is is a simple setup ".
The power is very similar to the ZDZ on a good can setup . The edge goes to the DA
My customers -who have both setups (which I did for them) repeatedly comment on this .
Both very smooth, both very similar in power both reliable and smooth.
I don't comment on other brands as I not used enough of them to get a good comparison - OR I don't like care for em .
Personal preference.
It seems everyone has a right to that -- don't they?
The design differences are pretty straightforward.
The reason I like singles --is that they are --to be blunt -- simple .
Simple to use and setup .
I have done lots of complex stuff- and frankly not very keen on it now gear drives - belt drives on multiple engines - etc., and I do have twins - which are great engines -I am doing a new plane now for a 160 twin -and a 210 twin and just setup a model for a customer with a DA100 twin -
These rotary valve 40/60/80 ZDZ singles tho, -really impress me -
As size goes up - the inertia from unbalance goes up - - I do understand that.
I also like small displacement 4 stroke glo singles -but above a certain size/ poweroutput - they are just too shaky.
The 80 is still an accectable size for a two stroke single and even with a pipe - still costs far less than any decent 100 twin -
Powerwise - this setup is comparable AND the ZDZ single and pipe is lighter - (than twin 100 cc engines I actually use)
I get no damage from the low end (3000rpm) out of balance period and the idle can be sorted out easily.
As for "stock muffler comparison ".
The so called stock in cowl devices are all aftermarket -for ZDZ engines
Carbs ?- the retrofits I have done were simply to put on stock Walbro carbs - and ZDZ now uses these.
comparisons -brand to brand are typically not really apples to apples.
What is a good exhaust for one engine is a looser on another - even within same brands.
One "100 " is less than and another 100 is more than 100 cc
yet no one rambles on about that.
A pipe on a ZDZ 80,setup right, gives a huge boost - yet retains smooth transition.
you can add pipes to some other brands and get only moderate boosts.and sometimes lousy transitions.
If I need to do a 100 twin -with small in cowl mufflers - I would --and I do use the DA100 twins -
As Dave Johnson notes " is is a simple setup ".
The power is very similar to the ZDZ on a good can setup . The edge goes to the DA
My customers -who have both setups (which I did for them) repeatedly comment on this .
Both very smooth, both very similar in power both reliable and smooth.
I don't comment on other brands as I not used enough of them to get a good comparison - OR I don't like care for em .
Personal preference.
It seems everyone has a right to that -- don't they?
05-01-2003, 09:25 PM
#54
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Hey Kris I had a lite weight ,cost less engine. It dident even take a pine tree to bust it up. I will gladly pay 200 to 300 more for durability. You Guys can go ahead and keep being mechanics, I had 15 good years of dealership life. Framing new houses is more fun. Do you know whats lower than a mechanic? New car salesmen. LOL
Kent
Kent
05-01-2003, 10:09 PM
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Say Shill:
I understand your point about a level playing field comparison, but nobody told DA that their engine had to displace exactly 100cc. Since it isn't Nascar or CART, there are no restrictions for displacement. For airplanes, the important characteristics are minimum engine weight, maximum power, and good throttle response. If someone can build an engine with 25% more displacement and power than DA, but still has the same weight and you can fit it into a plane with around 1800 square inches of wing.....wouldn't that be a better engine?
Also, there is no need to get carried away in the effort to reduce engine weight. If the engine weighs several pounds less than the DA, most planes will require adding nose weight to achieve balance. There is a point of diminishing returns on light weight engines in this class.
To be honest about it, most people would have to admit that either the DA or 3W motors provide a vast excess of power for planes of up to 2000 square inches and 30+ lbs. More power is just for bragging rights at ths point.
The bottom line is that we have more good choices than we've ever had for engines to power planes in the 22-30 lb range.
I understand your point about a level playing field comparison, but nobody told DA that their engine had to displace exactly 100cc. Since it isn't Nascar or CART, there are no restrictions for displacement. For airplanes, the important characteristics are minimum engine weight, maximum power, and good throttle response. If someone can build an engine with 25% more displacement and power than DA, but still has the same weight and you can fit it into a plane with around 1800 square inches of wing.....wouldn't that be a better engine?
Also, there is no need to get carried away in the effort to reduce engine weight. If the engine weighs several pounds less than the DA, most planes will require adding nose weight to achieve balance. There is a point of diminishing returns on light weight engines in this class.
To be honest about it, most people would have to admit that either the DA or 3W motors provide a vast excess of power for planes of up to 2000 square inches and 30+ lbs. More power is just for bragging rights at ths point.
The bottom line is that we have more good choices than we've ever had for engines to power planes in the 22-30 lb range.
05-01-2003, 11:47 PM
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Diablo
you have stated it really well but a 100 on a 30 pound airplane is a dog in my opinion but I am flying a Troybuilt extra at 22 pounds 12 ounces so ???. Actually you have stated it real well whis I had said all that. I was just trying to get the point out that most all comparisons are not equal> I have not said anything bad about any engine. I Like the competition as you say it gives us more and better products to choose from. You are correct about the weight of an engine and adding balast to make up for the lack of weight in an engine. So I have to say you have said a lot in that post but I am willing to bet alot of people do can not rationalize some of it.
Steve Hill
PS I just get tired of hearing all the hipe about some engines over others. Especially about the ZDZ 80 it is a good motor just not as good as some people want you to believe.
you have stated it really well but a 100 on a 30 pound airplane is a dog in my opinion but I am flying a Troybuilt extra at 22 pounds 12 ounces so ???. Actually you have stated it real well whis I had said all that. I was just trying to get the point out that most all comparisons are not equal> I have not said anything bad about any engine. I Like the competition as you say it gives us more and better products to choose from. You are correct about the weight of an engine and adding balast to make up for the lack of weight in an engine. So I have to say you have said a lot in that post but I am willing to bet alot of people do can not rationalize some of it.
Steve Hill
PS I just get tired of hearing all the hipe about some engines over others. Especially about the ZDZ 80 it is a good motor just not as good as some people want you to believe.
05-01-2003, 11:49 PM
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Diablo, on the subject of engines being too light. . My BME/pipes powered Fiberclassics 330lx is still nose heavy, this with nothing forward of the CG exceptthe powerplant and exhaust, and the batteries and servo tray 6" behind the CG. The total weight of the BME/pipes setup is 8 ounces LESS than a DA100 with standard exhaust mufflers.
I installed new batteries which dropped the weight 12 oucnes, making the plane 26 lbs even, about the lightest it could be, yet it is still nose heavy enough that it will not waterfall and requires a good amount of forward stick when inverted. The BME is turning a 28-12 mejzlik in excess of 6300 rpm and rips a lot while flying. . I can't go to a larger prop due to ground clearance issues, guess I'll have to get a 3-blade for it now.
Sorry, this disproves the theory about an engine being "too light" for an airframe. With nothing forward of CG except motor a BME is still too heavy. . . imagine that. Sure wish I had the 1/2 pound lighter Xtreme in the plane to get it to balance properly.
I installed new batteries which dropped the weight 12 oucnes, making the plane 26 lbs even, about the lightest it could be, yet it is still nose heavy enough that it will not waterfall and requires a good amount of forward stick when inverted. The BME is turning a 28-12 mejzlik in excess of 6300 rpm and rips a lot while flying. . I can't go to a larger prop due to ground clearance issues, guess I'll have to get a 3-blade for it now.
Sorry, this disproves the theory about an engine being "too light" for an airframe. With nothing forward of CG except motor a BME is still too heavy. . . imagine that. Sure wish I had the 1/2 pound lighter Xtreme in the plane to get it to balance properly.
05-02-2003, 12:06 AM
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But Kris:
I have a buddy with the Fiberclassics Extra and a DA-100.
His weighs 24 lbs.
Trying to understand where the advantage is to yours with a BME.
I have a buddy with the Fiberclassics Extra and a DA-100.
His weighs 24 lbs.
Trying to understand where the advantage is to yours with a BME.
05-02-2003, 12:15 AM
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Obviously either he got a lighter weight base airframe than mine ( there ARE manufacturing irregularities and variances) or the scale is off. Heck. . maybe MY scale is off and its really something like 23.5 lbs. . . . .Remember, this BARE airframe started at 14 lbs. . . Porky by anyones standards, especially when Radiocraft ARF's are about 11-12 lbs bare,a nd they are a bigger plane.
In any case, the BME setup is lighter than the DA setup, yet the plane is nose heavy. . where is the advantage (for balance purposes) of the heavier DA now?? It gets me to wondering where your buddy put the servos and batteries, and how far aft they had to be to get a proper CG.
In any case, the BME setup is lighter than the DA setup, yet the plane is nose heavy. . where is the advantage (for balance purposes) of the heavier DA now?? It gets me to wondering where your buddy put the servos and batteries, and how far aft they had to be to get a proper CG.
05-02-2003, 12:40 AM
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Hey Kris:
I've got a calibrated scale, and if my buddy lets me, I'll re-weigh his plane. But, if I remember correctly, he weighed it at UPS or the Post office. Anyway, he's here on RCU as Eagle 4442. He's posted some construction photos here too.
I've got a calibrated scale, and if my buddy lets me, I'll re-weigh his plane. But, if I remember correctly, he weighed it at UPS or the Post office. Anyway, he's here on RCU as Eagle 4442. He's posted some construction photos here too.
05-02-2003, 12:52 AM
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good deal, Diablo. . accurate numbers are a good thing to have. I'll see if I can find a decent scale to get a weight on mine. . the Wally World fish scale might not be entirely accurate.
05-02-2003, 01:03 AM
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We calibrate all of our scales based on two, O Haus triple beam scales.
I just weighed the assembled airframe of my new scratch built Giles 202- -a little over 8 lbs -
I know tho that it will have the weight doubled when the zdz60&can and the radio and the covering, etc., are added
1550 squares 85x85" not exact scale - clipped wings and a slightly stretched fuselage - I use the H9 330 cowl and canopy - it looks very scale .
No carbon fibre - all balsa fuse reglar ol foam wings and tail group -
I just weighed the assembled airframe of my new scratch built Giles 202- -a little over 8 lbs -
I know tho that it will have the weight doubled when the zdz60&can and the radio and the covering, etc., are added
1550 squares 85x85" not exact scale - clipped wings and a slightly stretched fuselage - I use the H9 330 cowl and canopy - it looks very scale .
No carbon fibre - all balsa fuse reglar ol foam wings and tail group -
05-02-2003, 01:18 AM
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I use a Berkley digital fish scale (50 lb max) which was calibrated using 1 kilo weights. The 1 kilo weights were weighed on a lab balance (which itself is accurate to less than 0.1 gram). The lab balance is calibrated using a known 1.000 kilo weight traceable back to NIST.
The Berkley fish scale is accurate to within 0.3 lbs in the weight range up to 30 lbs. It reads .3 lbs heavier than actual weight. At lower weights, the error is smaller. I made a calibration chart, so I just look up the error for the measured weight and get the true weight.
I have tested the scale and found it always reads the same...no drift over time.
The Berkley fish scale is accurate to within 0.3 lbs in the weight range up to 30 lbs. It reads .3 lbs heavier than actual weight. At lower weights, the error is smaller. I made a calibration chart, so I just look up the error for the measured weight and get the true weight.
I have tested the scale and found it always reads the same...no drift over time.
05-05-2003, 02:31 AM
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Well here is a picture of my newest airplane it is the one I was talking about weighing under 20 pounds. It has the ZDZ 80 and dry weight ready to fly is 19.8 pounds it is a 35% Extra 260 we call the Texas 260 it will drop a few more ounces as soon as I get the lithium ion batterys. The hatch and top of the cowl spinner wheel pants tail wheel and landing gear are yellow kevlar and carbon all made here locally by the designer builder of the plane. He made all of the plugs and molds. The canopy is carbon fiber that is inset into the hatch during the layup process the bottom of the cowl is also carbon fiber. I will start a thread in giant scale for it tomorrow. Look for this plane at the Joe Nall next Week.
Steve Hill
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05-05-2003, 11:08 AM
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Very nice -260 -
The 80 single should be a super match for it -
We have used that engine in models weighing 18 lbs -with no problems of airframe fatigue -
It is still the best 100 twin on the market ---
The 80 single should be a super match for it -
We have used that engine in models weighing 18 lbs -with no problems of airframe fatigue -
It is still the best 100 twin on the market ---
05-07-2003, 09:01 PM
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Hello Diablo
The wing span I believe is 103 inches I am not sure on the fuse length I have not measured it. I am on a busy schedule trying to get ready to go to Joe Nall I am trying to finish up another one of these planes with a BME 100 in it to go to I will try to post more info on the plane this weekend. My brother and the builder of the planes are leaving friday morning for south carolina and I still have to finish covering a wing for the other plane. I will be flying out Tuesday nextweek. Hope to see some of you people there.
Steve Hill
The wing span I believe is 103 inches I am not sure on the fuse length I have not measured it. I am on a busy schedule trying to get ready to go to Joe Nall I am trying to finish up another one of these planes with a BME 100 in it to go to I will try to post more info on the plane this weekend. My brother and the builder of the planes are leaving friday morning for south carolina and I still have to finish covering a wing for the other plane. I will be flying out Tuesday nextweek. Hope to see some of you people there.
Steve Hill
