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-   -   question about electric conversion on CG falcon III... (http://www.Wattflyer.com/forums/showthread.php?t=73529)

billp 04-09-2014 04:29 AM

question about electric conversion on CG falcon III...
 
y'all;
hello, im a newbie to rc planes.
i have a falconIII model plane that i finished converting to electric drive.
it was a kit i purchased over 20 years ago, and i finally got a chance to finish it this year.
the thing about the conversion, is that it bumped up the published flying weight from 4.5 lbs to 5 lbs, 12 oz.
the motor is an eflite power32, and the battery is a 4S, 3200mAh lipo.
the speed control is an eflite60 ESC.
now, i haven't flown the falconIII yet. i will be asking an experienced flyer at the flying club to take it up for a test flight.
however, before i do that, i would like to get any opinions from experienced flyers of the falconIII and falcon 56 airplanes, on the following question:

- is the current flying weight of my electric - converted falconIII
too heavy ???

thanx in advance, for your time.

billp

CHELLIE 04-09-2014 04:38 AM

Quote:

Originally Posted by billp (Post 944951)
y'all;
hello, im a newbie to rc planes.
i have a falconIII model plane that i finished converting to electric drive.
it was a kit i purchased over 20 years ago, and i finally got a chance to finish it this year.
the thing about the conversion, is that it bumped up the published flying weight from 4.5 lbs to 5 lbs, 12 oz.
the motor is an eflite power32, and the battery is a 4S, 3200mAh lipo.
the speed control is an eflite60 ESC.
now, i haven't flown the falconIII yet. i will be asking an experienced flyer at the flying club to take it up for a test flight.
however, before i do that, i would like to get any opinions from experienced flyers of the falconIII and falcon 56 airplanes, on the following question:

- is the current flying weight of my electric - converted falconIII
too heavy ???

thanx in advance, for your time.

billp


your good to go :D you have a big wing span and lots of Square Inches of surface.

http://www.carlgoldbergproducts.com/...ifications.gif
FALCON III Stock Number: GBGA0050 Kit Number: 50 Wingspan: 56" Wing Area: 558 Sq." Flying Weight: 4.5 lbs. Fuse Length: 47.5" Radio: 4-Channel Power: 2-stroke .35-.45 4-stroke .45-.65 INCIDENCE
(In Degrees) Wing: 0 Tail: 2 Engine: Right 2 Down 0 THROWS Aileron: 5/16-1/4" Elevator: 1/2" / 3/8" Rudder: 5/8" CENTER OF GRAVITY
Balance Point on fuse,
measured back from
wing leading edge 3-1/4" to 3-3/4"

billp 04-09-2014 04:44 AM

chellie, thank you for your reply.
im feeling better about the 1st test flight.
you have a great flying season for 2014 !!!!!
billp

CHELLIE 04-09-2014 04:59 AM

http://www.airfieldmodels.com/inform...ng_loading.htm


5.7 lbs x 2304 = 13132.8 Divided by 558 = 23.5 oz / FT

fhhuber 04-09-2014 05:07 AM

Falcons had an issue with the wings failing after a couple of years at the normal weight. I would look into reinforcing the main spar and dihedral bracing even if it hadn't come out heavier than as listed on the box.

billp 04-09-2014 05:15 AM

fhhuber;
i did not know that fact.
i did however, during the build, extended the fiberglass coverage (epoxy based) to cover the balsa sheeted center of the wing, both top and bottom sides, using light fiberglass cloth. i hope this helps in reinforcing the wing.
thank you for the heads up on this known weakness in the wing.
billp

kyleservicetech 04-09-2014 05:29 AM

Quote:

Originally Posted by billp (Post 944951)
y'all;
hello, im a newbie to rc planes.
i have a falconIII model plane that i finished converting to electric drive.
it was a kit i purchased over 20 years ago, and i finally got a chance to finish it this year.
the thing about the conversion, is that it bumped up the published flying weight from 4.5 lbs to 5 lbs, 12 oz.
the motor is an eflite power32, and the battery is a 4S, 3200mAh lipo.
the speed control is an eflite60 ESC.
now, i haven't flown the falconIII yet. i will be asking an experienced flyer at the flying club to take it up for a test flight.
however, before i do that, i would like to get any opinions from experienced flyers of the falconIII and falcon 56 airplanes, on the following question:

- is the current flying weight of my electric - converted falconIII
too heavy ???

thanx in advance, for your time.

billp

I've run your numbers through www.motocalc.com. Motocalc predicts that your motor will work well with a 12X6 APC-E prop on a 4S LiPo. Predicted power is 48 Amp, 670 Watts, with the motor turning that prop at about 9600 RPM. Motocalc predicts a climb out rate of 1600 feet per minute. This power system is running about 120 watts per pound of airplane. That is decent performance for this model.

It would be safe to run that motor with a 13X6 prop. But, don't do it unless you have access to one of those wattmeters, to make certain not to fry anything.

Five pounds, 12 ounces seems rather heavy for a Falcon 56. Have you weighed it with an accurate scale?

As for that Power 32, these electric power systems can have surprising power outputs, compared to a glow engine. The Power 32 motor has roughly the same horsepower as a glow four stroke 60 or 70 engine. I flew a Falcon 56 model back in the mid 1960's as glow power, using an Enya 35 Glow engine. It flew fairly well back then. Don't know about wing strength though, might be something to really take a close look at.

http://www.wattflyer.com/forums/showthread.php?t=73275

This guy is running a Power 60 motor and a 6S LiPo in his model, with a total weight of 7 pounds.
https://www.youtube.com/watch?v=nm1la-ChLF8

That's strange on that Power 60 Motor. Motocalc predicts this motor will only be running about 500 watts, with 80% efficiency. Planting a similar sized Hacker A50-12S motor with a 15X10 prop and a 5S LiPo will haul this model straight up at some 3000 feet per minute. And, probably tear the wings off. (I've got three Hacker A50-12S motors in my various models. Those models have about 65 inch wingspan, and are running about 8 pounds and 1300 Watts.)

billp 04-09-2014 05:37 AM

kyleservicetech;
wow, okay, i am running an apc 12" prop (12x8) so i hope the slight difference in pitch will not hinder performance too much.
i used my digital kitchen scale for the weighing of the plane, im pretty sure it can handle 6 lbs, so i think the weight is correct.
thank you for your link to motocalc, i need to check that out. its all quite fascinating !!!
billp

kyleservicetech 04-09-2014 06:01 AM

Quote:

Originally Posted by billp (Post 944961)
kyleservicetech;
wow, okay, i am running an apc 12" prop (12x8) so i hope the slight difference in pitch will not hinder performance too much.
i used my digital kitchen scale for the weighing of the plane, im pretty sure it can handle 6 lbs, so i think the weight is correct.
thank you for your link to motocalc, i need to check that out. its all quite fascinating !!!
billp

Yeah
A 12-8 prop will be pulling the model faster through the air. You might try picking up both the 12-6 and 12-8 props and compare them.

That motocalc program is free for 30 days, then $39. There are also a few free computer programs out there, but IMHO, none provides as much information on your model and how it will fly as the motocalc program.

fhhuber 04-09-2014 06:35 AM

I suspect that one of the reasons for the Falcon wings folding is the pilots flying them more aggressively than what they were really intended for. When it was designed people were thrilled to be able to (barely) loop from level flight. The more powerful engines that got put on, when available, allowed pulling higher G and thus applied more stress to the wings. The higher stresses applied repeatedly for years eventually cracked the dihedral brace or spar.

Yes, fiberglassing the wing joint at the sheeting will help spread some load from the spar to the sheeting. This can be very effective in some models. I haven't looked at the plans of a Falcon in a very long time so can't say if that would be enough for typical performance expectations of an advanced trainer today.

Realize that the plane may be capable of being overstressed in aerobatics... just don't push it too far and it should give you a lot of flying time.

The Power32 will handle the APC 12X8 just fine. It will push your 60 amp ESC close to or a bit beyond its 60 amp rating on 4S though. I burned up an E-Flite 60 amp ESC using the APC 12X8 with a Power 32. I'd recommend using the 12X6 instead.

CHELLIE 04-09-2014 09:10 AM

Quote:

Originally Posted by kyleservicetech (Post 944960)
I've run your numbers through www.motocalc.com. Motocalc predicts that your motor will work well with a 12X6 APC-E prop on a 4S LiPo. Predicted power is 48 Amp, 670 Watts, with the motor turning that prop at about 9600 RPM. Motocalc predicts a climb out rate of 1600 feet per minute. This power system is running about 120 watts per pound of airplane. That is decent performance for this model.

It would be safe to run that motor with a 13X6 prop. But, don't do it unless you have access to one of those wattmeters, to make certain not to fry anything.

Five pounds, 12 ounces seems rather heavy for a Falcon 56. Have you weighed it with an accurate scale?

As for that Power 32, these electric power systems can have surprising power outputs, compared to a glow engine. The Power 32 motor has roughly the same horsepower as a glow four stroke 60 or 70 engine. I flew a Falcon 56 model back in the mid 1960's as glow power, using an Enya 35 Glow engine. It flew fairly well back then. Don't know about wing strength though, might be something to really take a close look at.

http://www.wattflyer.com/forums/showthread.php?t=73275

This guy is running a Power 60 motor and a 6S LiPo in his model, with a total weight of 7 pounds.
https://www.youtube.com/watch?v=nm1la-ChLF8

That's strange on that Power 60 Motor. Motocalc predicts this motor will only be running about 500 watts, with 80% efficiency. Planting a similar sized Hacker A50-12S motor with a 15X10 prop and a 5S LiPo will haul this model straight up at some 3000 feet per minute. And, probably tear the wings off. (I've got three Hacker A50-12S motors in my various models. Those models have about 65 inch wingspan, and are running about 8 pounds and 1300 Watts.)

+1 :ws: Yes its a tad on the Heavy side, but not to worry, yes that power 32 is a Equivalent 60 size motor in reality, and will pull that plane with Authority :D E Flite motors are underrated, I get to do the Maiden Flight on it :D :D :D LOL , Ok, Just kidding :ws: Take care and have fun, Chellie

CHELLIE 04-09-2014 09:16 AM

Billp, There are a lot of E Power Gurus Here on this Forum, They will point you in the Right Direction, I have Learned a Lot from them, and that makes me Dangerous :Q :D :ws: Take care, Chellie

billp 04-10-2014 03:31 AM

okay, the xtra weight belongs to my orig choice of landing wheels...
 
y'all;
after reading the replies about my slight weight problem with the falcon, i removed my 5" balloon tires and voila... i shaved exactly 1 lb, and 3/8 oz off the weight of my plane. today, wed, i dropped by the LHS, and picked up a pair of 5" dave brown big flite wheels, which came in at 5 and 3/8 oz TOTAL; big change....
so, my flying weight is now, 5 lbs, and 1 oz.
the balloon tires i will keep for the time being, i may use them on another plane in the future.
thank you to all who had replied to my initial posting, it forced me to examine what i had done, to add that much more weight to my falconIII.
i had changed it from a tricycle to a tail dragger, and i also used an aluminum landing gear mount for the 2 wheels. so, in the end, i added an additional 9 oz to the ideal weight for the plane..... whew.....again, many thanx to all who had replied...!!!!!!!!
billp

kyleservicetech 04-10-2014 04:58 AM

Quote:

Originally Posted by billp (Post 945041)
y'all;
after reading the replies about my slight weight problem with the falcon, i removed my 5" balloon tires and voila... i shaved exactly 1 lb, and 3/8 oz off the weight of my plane. today, wed, i dropped by the LHS, and picked up a pair of 5" dave brown big flite wheels, which came in at 5 and 3/8 oz TOTAL; big change....
so, my flying weight is now, 5 lbs, and 1 oz.
the balloon tires i will keep for the time being, i may use them on another plane in the future.
thank you to all who had replied to my initial posting, it forced me to examine what i had done, to add that much more weight to my falconIII.
i had changed it from a tricycle to a tail dragger, and i also used an aluminum landing gear mount for the 2 wheels. so, in the end, i added an additional 9 oz to the ideal weight for the plane..... whew.....again, many thanx to all who had replied...!!!!!!!!
billp

OK

Shaving a pound of weight from your model makes a substantial difference in performance with that Power 32 motor setup. Motocalc predicts that the model will climb out at 45 degrees at some 1700 feet per minute. Your model is also running some 140 Watts per pound of airplane, which should make for a very nice flying model. Wouldn't be surprised it it would fly straight up for a considerable distance before running out of steam.

FYI, 140 watts per pound will NOT be under powered. At least for most people. :D :cool:

fhhuber 04-10-2014 04:09 PM

140 watts/lb is enough for mild 3D... it will hover and will accelerate vertically out of hover with the correct prop.

Plenty of power for anything the Falcon is capable of and more... easily capable of pulling the plane through maneuvers and pulling the wings off the airplane. You'll need to avoid attempting excessively aggressive aerobatics.

kyleservicetech 04-10-2014 10:57 PM

Quote:

Originally Posted by fhhuber (Post 945083)
140 watts/lb is enough for mild 3D... it will hover and will accelerate vertically out of hover with the correct prop.

Plenty of power for anything the Falcon is capable of and more... easily capable of pulling the plane through maneuvers and pulling the wings off the airplane. You'll need to avoid attempting excessively aggressive aerobatics.

I've got a Vyper 3D model that was picked up for free from a club member. Had to add wheels, radio, motor, ESC and stuff. This model has huge ailerons, rudder and elevator surfaces though.

Would the Falcon have enough aileron/rudder/elevator authority to allow safe 3D flying?

fhhuber 04-10-2014 11:17 PM

https://www.youtube.com/watch?v=VjAg7V08s2Y

Can't find the video I was looking for of someone hovering an Avistar using a .32 glow engine.

billp 04-28-2014 12:59 AM

one of the 3D flyers took the electric falconIII up today, apr. 27 ...
 
so, today, my falconIII finally flew, for the first time.
one of the experienced 3D flyers graciously took on the task of taking it up.
i changed my battery choice to a 4S - 3700 pack since i had 3 of these.
it also added abit more weight, to its current new weight of 5lbs, 8 ozs.
yes, i know its almost at its original weight with the balloon tires. so, i was abit concerned.
'm' took off from the runway, and it was airborne before travelling 30 feet.
he flew for about 5 mins... doing some regular full field eights, and some rolling climbouts, and straight climbouts. for a plane that is that heavy, i found it was kinda floating in the air at slow speed. yes, as you all pointed out, it is a slow plane. i was expecting it to be abit fast, but thank goodness, it is not. 'm' flew it fast, and slow, and it reacted the way he expected.
suffice it to say, even with its extra 1lb of weight, it flys quite well.
thank you to all who had replied to this thread, for all your help in getting my plane ready for its maiden flight.
i will be flying it in the next few weeks. can't wait for it.
it will be an interesting summer this year for sure !
billpong

kyleservicetech 04-28-2014 01:18 AM

Quote:

Originally Posted by billp (Post 946699)
so, today, my falconIII finally flew, for the first time.
one of the experienced 3D flyers graciously took on the task of taking it up.
i changed my battery choice to a 4S - 3700 pack since i had 3 of these.
it also added abit more weight, to its current new weight of 5lbs, 8 ozs.
yes, i know its almost at its original weight with the balloon tires. so, i was abit concerned.
'm' took off from the runway, and it was airborne before travelling 30 feet.
he flew for about 5 mins... doing some regular full field eights, and some rolling climbouts, and straight climbouts. for a plane that is that heavy, i found it was kinda floating in the air at slow speed. yes, as you all pointed out, it is a slow plane. i was expecting it to be abit fast, but thank goodness, it is not. 'm' flew it fast, and slow, and it reacted the way he expected.
suffice it to say, even with its extra 1lb of weight, it flys quite well.
thank you to all who had replied to this thread, for all your help in getting my plane ready for its maiden flight.
i will be flying it in the next few weeks. can't wait for it.
it will be an interesting summer this year for sure !
billpong

Compared to the mid 1980's most of those electric models we flew back then were really under powered. Those that I flew were "Launch" power systems for electrified sailplanes. The first half dozen electrified models I flew used motors from work that I rewound to get more power and RPM. It was a good day when one of those sailplanes got up to a few hundred feet before the rewound motor blew its commutator.

Move up to the current time, it is almost difficult to build an electrified model that IS underpowered, assuming the use of decent quality motors/esc's/battery systems.

How times have changed in the past few years with this electric powered model airplane stuff. :cool:

RV Winkle 04-30-2014 05:17 PM

so do we get a pic of the falcon?


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