Light weight EDFs

[Quorneng]

I scratch build foam planes using thin foam sheet, usually 3 mm. The idea material if Depron but the real stuff is no longer made.
Where light weight building really pays is with EDFs. If you can build light enough than a much smaller and lighter EDF + battery will still give an appropriate performance. This concept also has benefits in scale builds as a scale inlet is now likely to be adequate without resorting to cheat holes!
This scale DH Venom demonstrated the principles involved.

It is definitely not a UMX with a span of 1130 mm (44.5") yet is uses just a 40 mm EDF. With a 1400mAh 4s it still only weighs 513g (18 oz). A side benefit of such a small EDF is the inlets are scale as is the exhaust nozzle. As I fly from a grass field it is an easy hand launch/belly land. Only foam there is no other reinforcing.
It is based on a Venom used by the Swiss Airforce aerobatic team. Yes a bit delicate but it flies superbly and if required at much reduced throttle too!

It glides pretty well too.

Another way of achieving a similar effect is airliners that use huge turbofans.
I established that such a plane did not need an EDF at all but would get sufficient thrust using a much lighter drone motor and a 5x4.5 four blade ducted prop!
My first attempt was an airbus A350. Again built from 3 mm sheet foam with printed nacelles and pylons.
Still a hand launch and belly land it despite being rather bigger it weighs little more than the Venom at 585g (20,6 oz) and it only need a1000mAh 4s!

Only a little balsa wood in the main spar everything else is foam.
It flies far better than I ever dared to hope.

 

[Tunedfrog]

Welcome in @Quorneng , impressive work and awesome flying. Thanks for sharing.

 

[Doom!]

I love seeing scratch built planes. It really sucked when Depron stopped being available. Welcome to the Forum.

 

[CertifiedMike]

I scratch build foam planes using thin foam sheet, usually 3 mm. The idea material if Depron but the real stuff is no longer made.
Where light weight building really pays is with EDFs. If you can build light enough than a much smaller and lighter EDF + battery will still give an appropriate performance. This concept also has benefits in scale builds as a scale inlet is now likely to be adequate without resorting to cheat holes!
This scale DH Venom demonstrated the principles involved.
View attachment 216879
It is definitely not a UMX with a span of 1130 mm (44.5") yet is uses just a 40 mm EDF. With a 1400mAh 4s it still only weighs 513g (18 oz). A side benefit of such a small EDF is the inlets are scale as is the exhaust nozzle. As I fly from a grass field it is an easy hand launch/belly land. Only foam there is no other reinforcing.
It is based on a Venom used by the Swiss Airforce aerobatic team. Yes a bit delicate but it flies superbly and if required at much reduced throttle too!

It glides pretty well too.

Another way of achieving a similar effect is airliners that use huge turbofans.
I established that such a plane did not need an EDF at all but would get sufficient thrust using a much lighter drone motor and a 5x4.5 four blade ducted prop!
My first attempt was an airbus A350. Again built from 3 mm sheet foam with printed nacelles and pylons.
Still a hand launch and belly land it despite being rather bigger it weighs little more than the Venom at 585g (20,6 oz) and it only need a1000mAh 4s!
View attachment 216882
Only a little balsa wood in the main spar everything else is foam.
It flies far better than I ever dared to hope.

Excellent flying machine you built!!! It looks very stable in the air! Beautiful plane!

 

[tudordewolf]

I dig the elegance of light weight rather than brute force. Anything will fly with a positive thrust-to-weight ratio, but optimizing a build is an art.

I recently finished a biplane which had a suggested battery of 1300-1800mah 3s and a ~520g flying weight. I was able to get it down to 395g on just a 500mah 3s by also changing the ESC, motor, and prop, and I'm much more excited for that than a brick with double its weight in thrust.

 

[Quorneng]

I scratch build foam planes using thin foam sheet, usually 3 mm. The idea material if Depron but the real stuff is no longer made.
Where light weight building really pays is with EDFs. If you can build light enough than a much smaller and lighter EDF + battery will still give an appropriate performance. This concept also has benefits in scale builds as a scale inlet is now likely to be adequate without resorting to cheat holes!
This scale DH Venom demonstrated the principles involved.
View attachment 216879
It is definitely not a UMX with a span of 1130 mm (44.5") yet is uses just a 40 mm EDF. With a 1400mAh 4s it still only weighs 513g (18 oz). A side benefit of such a small EDF is the inlets are scale as is the exhaust nozzle. As I fly from a grass field it is an easy hand launch/belly land. Only foam there is no other reinforcing.
It is based on a Venom used by the Swiss Airforce aerobatic team. Yes a bit delicate but it flies superbly and if required at much reduced throttle too!

It glides pretty well too.

Another way of achieving a similar effect is airliners that use huge turbofans.
I established that such a plane did not need an EDF at all but would get sufficient thrust using a much lighter drone motor and a 5x4.5 four blade ducted prop!
My first attempt was an airbus A350. Again built from 3 mm sheet foam with printed nacelles and pylons.
Still a hand launch and belly land it despite being rather bigger it weighs little more than the Venom at 585g (20,6 oz) and it only need a1000mAh 4s!
View attachment 216882
Only a little balsa wood in the main spar everything else is foam.
It flies far better than I ever dared to hope.

Probably the ultimate in "daft" lightweight building is my EDF Concorde/
I judged it could make do with four light weight and relatively low power 40mm EDFs. These EDFs could be mounted directly in the scale JET pipes.

Having gone to the trouble to have true scale size nacelles I felt the wing had to be scale too with all the twist and bends of the full size. I based it on this incredible photo taken at Heathrow.

A simple flat wing it is not!
Built almost entirely in 2mm Depron, yes it was available and no reinforcing anywhere!
As you can imagine it was not a rapid build.

Without undercarriage I judged it would be light enough, and thus fly slow enough, to be an easy hand launch. I was confident such a delta when close to the ground would readily "float" to an acceptable landing speed.

Just over 8 foot long bur with a span of just 3 ft!
It did take a while before the EDF and ESCs performed properly. It was also my first to use the much lighter solid magnet wire as the distances between the EDFs and ESCs was so great. Everything is powered by a single 3000mAh 2s.
it did eventually demonstrate everything I had hoped for. A simple "no panic" hand launch, excellent flight characteristics and a no damage flop landing.

It sounds impressive and even flies at something like scale speed. Concorde was speed limited to 350 knots at "airshow" altitudes.
I still have it but I just can't imagine I will ever do something similar again.

 

[Quorneng]

Although I don't normally buy RTFs or kits when I started serious RC about 20 years ago after the usual "career interruption" I knew little about how electric had progressed so I did indeed buy an RTF. An Art-Tech Wing Dragon 4 pusher.

Even back then it was a bit old technology (Brushed motor, NiMh batteries) but it was on offer cheap!
As I fly from a rather rough field it was always going to be a hand launch. Flight duration was not exactly long but to my surprise it did exactly what it said "on the box".
As a life long modeller it was not long before I started to think of ways to make it better.
First to go were the 9g servos and the stiff moulded hinges replaced by 3.7g micro servos with full length top tape hinges along with mechanical aileron differential so the rudder was no longer essential.

So 3x3.7g rather than 4x9g and with a much improved installation.
No U/C reduced drag and weight further so there was some modest improvement in performance.
The next big jump came from a built up Depron wing rather than the solid foam of the original.
To cut a long story short the 5th version was built like this with a balsa/Deprom/balsa spar.

Note the tapered spar flanges are actually held within the thickness of the wing skin.

By now it had an Emax 2815 brushless motor and a 1500mAd 3s LiPo.

My Wing Dragon was now 2/3 weight (16oz) with over 5 times the "cruise" endurance (30 minutes) as well as the power for serious aerobatics.
The wing was plenty strong enough to lift at least the original weight so I wondered how big a battery could be added and how long would it fly
By inserting a 5000mAh 2s I found out. A full 90 minutes and a rather stiff neck!

To discharge a 5000mAh battery in 90 minutes to say 85% means an average draw of about 2.2 amps and that covers everything.
Now if I designed a Wing Dragon version specifically for "Endurance " how long could a flight be?
Remember this was in 2009 when such a duration was unusual for a modest (40") plane. You can see where my passion for light weight construction started.
To be continued
.

 

[Quorneng]

Endurance
I reasoned that I I could get the minimum cruise amps to an average of 1 or even less I would be able to fly rhe plane for 5 hours using the 5000mAh battery.
As i did not like the concept of repeated long test flights I constructed a battery the size and weight of the 5000mAh but electrically only held a 1000mAh 2s with the rest made up of lead! The task was to improve the plane to the point that it would fly for 1 hour on the reduced battery then 5 hours would be possible with the full 5000maH one.
Still keeping to the 48" span limit the plane went though many iterations before eventually a flight of 61 minutes was achieved.
This is the final version.

A simple pylon pod and boom pusher with a broad chard wing. It uses a 20g Blue Wonder 1200kV motor driving a 9x4.5 prop. It weighs 436g (15.4oz) of which the 5000m/ah battery accounts for 210g! Perhaps its most unusual feature are its direct coupled aileron servos to avoid any external horn or linkage.

It does fly slowly, after all it is not intended to go anywhere, but at full power it still has quite an aerobatic performance.

It is doing all this with a battery that nearly equals its empty weight.

 

[CertifiedMike]

Endurance
I reasoned that I I could get the minimum cruise amps to an average of 1 or even less I would be able to fly rhe plane for 5 hours using the 5000mAh battery.
As i did not like the concept of repeated long test flights I constructed a battery the size and weight of the 5000mAh but electrically on held a 1000mAh 2s with the rest made up of lead! The task was to improve the plane to the point that it would fly for 1 hour then 5 hours would be possible with the full battery.
Still keeping to the 48" span limit the plane went though many iterations before eventually a flight of 61 minutes was achieved.
This is the final version.
View attachment 218395
A simple pylon pod and boom pusher with a broad chard wing. It uses a 20g Blue Wonder 1200kV motor driving a 9x4.5 prop. It weighs 436g (15.4oz) of which the 5000m/ah battery accounts for 210g! Perhaps its most unusual feature are its direct coupled aileron servos to avoid any external horn or linkage.
View attachment 218413
It does fly slowly, after all it is not intended to go anywhere, but at full power it still has quite an aerobatic performance.

It is doing all this with a battery that nearly equals its empty weight.

Reading that you could fly this plane for 5 hours made me laugh! FANTASTIC!!!
Maybe its because you are a good pilot but to me, this looks like its small and lightweight and slow enough for a beginner like myself to be able to learn with and hopefully not destroy with the inevitable crash landings it will receive!
I really like this plane and how it looked in the air.
Great job!

 

[Quorneng]

Yes it is relatively easy to fly mainly because it does everything slowly but to be honest I never flew it for 5 hours non stop. the longest single flight I made was just over 2 hours and it convinced me the limit of endurance was me not the plane!
I still have it but now fly it with some minor adjustment using a 3500mAh 2s. After all 3.5 hours is still plenty. I have taken it to some club open days and it does amuse onlookers when I fly repeatedly for most of a morning and don't change the battery.
It biggest weakness is it does need pretty calm weather.

 

[CertifiedMike]

Yes it is relatively easy to fly mainly because it does everything slowly but to be honest I never flew it for 5 hours non stop. the longest single flight I made was just over 2 hours and it convinced me the limit of endurance was me not the plane!
I still have it but now fly it with some minor adjustment using a 3500mAh 2s. After all 3.5 hours is still plenty. I have taken it to some club open days and it does amuse onlookers when I fly repeatedly for most of a morning and don't change the battery.
It biggest weakness is it does need pretty calm weather.

I think maybe it would be ok. I don't think I'd be too tempted to try and fly my plane until I had at least some chance of landing, not crashing in windy conditions.
3.5 hours... Awesome!!!
Maybe I can find a super slow glider to fly indoors for the winter...

 

[Doom!]

For me anything over 30 minutes is to long to be staring up at the sky.

 

[Quorneng]

Althoug the challenge to create super long flights was technically interesting my first love is designing and building scale planes usually with some uncommon technical feature. Not a common or garden F16 for me!
A vertical take off is a challenge particularly the transition to straight and level flight. Most have done this using drone technology. I do have a conventional drone and its ability to VTOL under cotrol is remarkable and very much down the sophistication of its electronics.
I wondered what might be possible with simple gyro assist rather than full stabilisation.
The next question was what scale plane? should it be based on. Right at the end of WWII Von Braun developed a V2 with wings called the A4b to increase its range by gliding.

.
A 1945 picture of full size A4b

A quick drawing suggested a 70mm EDF would fit in the tail and if given a set of big enough cheat holes might allow sufficient thrust if the rest of the body was light enough.
First a trial EDF and cheat holes.

A thrust test of the "all cheat hole" duct.

Convinced me that in principle the 70 mm AEO when over rated to 4s could provide a thrust to weight significantly in excess of 1:1.
As success was by no means guaranteed I decided to build a slightly small non VTO version using a 55mm EDF to test the aerodynamics of the airframe design and construction.

Note it has no ailerons but relies on elevons and rudderons for roll control.
I even built a simple profile chuck glider to establish a reasonable CG position.

With a Lemon gyro Rx set to "rate" only it flew pretty well although the use of rudderons as well as elevons proved un necessary meaning only a single servo would be required giving a useful weight saving.
The 27% bigger VTO version build in a similar way but no a process for the faint hearted.
Formers

Ring formers

The first planks

The fuselage centre section with the first four planks out of an eventual total of 28.

The completed VTO version on its take off stand.

Still Using the Lemon stab Rx in "rate only" mode the first VTO take off was very much an "all or nothing" event.

I was completely alone for the maiden. This picture was taken using a tripod and a time delay!
I need not have worried the take off was almost a non event! Even more important once altitude was reached which happened very quickly a throttle back and it flew and landed perfectly as a normal RC plane.

Note the motor torque is such that the V2 spirals as it climbs which actually helps to keep it pointing vertically.
Although the full power duration is very limited before something over heats (30 seconds?) it flies on such a reduced throttle once at altitude that flights of 6 minutes are possible including some simple aerobatics.
Light weight has considerable advantages.

 

[CertifiedMike]

It flies beautifully! Cool project!!!

 

[Hobbydude2]

Althoug the challenge to create super long flights was technically interesting my first love is designing and building scale planes usually with some uncommon technical feature. Not a common or garden F16 for me!
A vertical take off is a challenge particularly the transition to straight and level flight. Most have done this using drone technology. I do have a conventional drone and its ability to VTOL under cotrol is remarkable and very much down the sophistication of its electronics.
I wondered what might be possible with simple gyro assist rather than full stabilisation.
The next question was what scale plane? should it be based on. Right at the end of WWII Von Braun developed a V2 with wings called the A4b to increase its range by gliding.
View attachment 218561.
A 1945 picture of full size A4b
View attachment 218568
A quick drawing suggested a 70mm EDF would fit in the tail and if given a set of big enough cheat holes might allow sufficient thrust if the rest of the body was light enough.
First a trial EDF and cheat holes.
View attachment 218563
A thrust test of the "all cheat hole" duct.
View attachment 218565
Convinced me that in principle the 70 mm AEO when over rated to 4s could provide a thrust to weight significantly in excess of 1:1.
As success was by no means guaranteed I decided to build a slightly small non VTO version using a 55mm EDF to test the aerodynamics of the airframe design and construction.
View attachment 218570
Note it has no ailerons but relies on elevons and rudderons for roll control.
I even built a simple profile chuck glider to establish a reasonable CG position.
View attachment 218571
With a Lemon gyro Rx set to "rate" only it flew pretty well although the use of rudderons as well as elevons proved un necessary meaning only a single servo would be required giving a useful weight saving.
The 27% bigger VTO version build in a similar way but no a process for the faint hearted.
Formers

Ring formers
View attachment 218572
The first planks
View attachment 218573
The fuselage centre section with the first four planks out of an eventual total of 28.
View attachment 218574
The completed VTO version on its take off stand.
View attachment 218575
Still Using the Lemon stab Rx in "rate only" mode the first VTO take off was very much an "all or nothing" event.
View attachment 218576
I was completely alone for the maiden. This picture was taken using a tripod and a time delay!
I need not have worried the take off was almost a non event! Even more important once altitude was reached which happened very quickly a throttle back and it flew and landed perfectly as a normal RC plane.

Note the motor torque is such that the V2 spirals as it climbs which actually helps to keep it pointing vertically.
Although the full power duration is very limited before something over heats (30 seconds?) it flies on such a reduced throttle once at altitude that flights of 6 minutes are possible including some simple aerobatics.
Light weight has considerable advantages.

Ach du lieber! The British are now skeered!

 

[Quorneng]

Based on the principles I used for the Airbus A350 using a quad motor and multiblade prop for a big turbofan rather than a true EDF.

I decided to try something bigger and chose the huge AN124 Ruslan wich is considered the biggest plane to ever go into series production.
It only when you see it in relation to people do you see how big it is.

As the engine nacelles are printed having 4 rather than two would not be a problem but the huge and more complex fuselage shape suggested using printed fuselage formers and printed wing ribs as well.
As with the A350 the overall size of the plane was set by the 3" 4 blade props in the turbofan nacelles. The result gave a wing span of 2.25 m so a 3 piece wing would be needed.
The fuselage formers are huge, Printer bed limitations meant they had to be printed in sections and glued together.

As there were over 100 fuselage former parts this was not going to be a quick build.
The fuselage is built as a half shell over the plan and carefully clad in 3mm sheet foam.

Overall the fuselage construction gives an almost scale internal space.

Even some of the printed wing ribs had to be printed is parts. The set of ribs for half of the wing centre section which carries the 4 engine nacelles.

The LH wing with e nacelles in place.

First assembly giving an idea of its size.

The wing root proved thick enough to hold the batteries which meant the fuselage would be completely empty! On this basis I just had to make the scale nose section removeable so you could see inside.

One last problem was would the fuselage fit in my Renault Clio?

Just but it was a good thing that nose was removable.
Although big it is still light weighing just over a 1200 g so can be hand launched easily enough. To my delight it flies nicely and also realistically slowly!

Worth all the effort? Not really but satisfying none the less.

 

[CertifiedMike]

I am amazed that this is all built 'at home'. The construction is so cool!!! It looks very stable in your video. Fantastic job on a monster sized plane!!!

 

[Doom!]

You've done some killer builds.

 

[Quorneng]

I am amazed that this is all built 'at home'. The construction is so cool!!! It looks very stable in your video. Fantastic job on a monster sized plane!!!

More by luck than anything else I got the CG more or less right although I expect the design of the full size as a transport plane does have a fairly wide CG tolerance. In addition I did fit a Lemon stab Rx in "rate" mode which always "tames down" a planes reaction in flight. The video was only its second flight so I did not switch it off although later flights did demonstrate its gentle characteristics with the gyro switched off.
Just to complete the story it did have a serious accident when one wing outer panel worked loose and not surprisingly it spun in!

The benefit of printed formers meant rebuilding the fuselage was not a bad as it might have been so on the principle "if you have designed and built it you can repair it" it duly was with a slightly different paint scheme.

The reason the outer wing came off was due to it being just a push fit. On the rebuild a small locking screw was added to each wing panel to make sure it didn't happen again!

How do you hand launch such a big fuselage that you cannot possible hold in your hand?
The answer is "bowling ball" type finger holes on the under side!

It is also fortunate that although I am left handed I learned to fly right handed (mode 2) so it means I can launch with my "good" arm and fly all by myself.