18" Rubber-Powered Contra-Rotating Koolhoven FK-55 - New Flights

Three flights by the 18" rubber-powered Koolhoven FK-55 by Tom Hallman at Wawayanda, NY on 8.3.21. The model has contra-rotating props via a Contra-Rotating Prop Drive unit (CRPD) designed by Keith Sterner, however the units are not longer being produced. Model is loosely based on this 1937 plan & article from Model Airplane News: www.hallmanstudio.com/Koolhove...
Music via motionarray.com.
The unit is more closely shown about 25 seconds in on this film: • 18" Rubber-Powered Con...
Filmed by Tom Hallman & Peter Kaiteris with a Canon PowerShot SX20-IS, iPhone 11 Pro, and a Nikon D3400 70-300mm.
***Interview with Tom Hallman by John McAvoy on his Free Flight Fanatic podcast:
freeflightfanatic.libsyn.com/...
Flying Aces Club merchandise: www.cafepress.com/flyingacesclub
Center of Gravity merchandise: www.cafepress.com/centergravity
For more info on free-flight rubber-powered models, check these websites:
www.easybuiltmodels.com/
www.volareproducts.com/BUY/
www.flyingacesclub.com
outerzone.co.uk/index.asp
National Free Flight Society - freeflight.org/
Mike Stuart's Flying Scale Models - www.ffscale.co.uk/
www.freeflightsupplies.co.uk/...

[@mpojr]

l been flying model airplanes for 50 years mostly rc ,,,but with that said all models have one thing in common they will seek out the ditch or a sign that could be 400yards away seen it happen to many times.saw one fly through a porta john once luckly nobody was in it ;l enjoy your channel Tom you are a good builder and flyer

[@demietrilazarakis283]

For the Love of aeromodeling! Who knew you could do counter rotating props on a rubber powered plane? Amazing

[@malavshah5997]

Second that !

[@josephwolf1]

There is nothing more relaxing then watching your videos. When I think of perfection I think of your models and your skills. Thank you for shearing your knowledge and flights. Happy landings.

[@williamrobinson7435]

Wonderful! The power evident at 1600 turns was amazing.. I reckon the best pulling ratio in the early flight is about at that level. Lovely plane, thanks for posting!

[@jehoiakimelidoronila5450]

Amazing... simply amazing. At least the design lives on in the form of that. One of my many goals in life is to recreate an actual k.v.55, but with a modern twist. If the philippine aviation industry here were that interested.

[@davidfranklin5270]

Another great happy uplifting moment to start my day. I am always inspired by your skill in construction, trimming, dedication and contribution to rubber powered freeflight modeling.

[@sailr]

I have the greatest respect for you rubber flyers. Your patience is way beyond mine. I have thought about building a rubber bird but know I would be greatly frustrated by all the fiddly stuff getting it to fly right.

[@walk4718]

That final flight, so exciting. Counter rotating systems have always been fascinating. Excellent job modeling this in such a compact unit

[@jeffwalther3935]

There it is again, the peerless art of rbpff, ART enhanced by science and technology in the use of counterrotating ff propulsion delivered an altogether identical experience I/we got seeing that gorgeous all-red airplane fly and ONLY in the classic childrens' short film "The Red Balloon"; in my estimation, the most heartwarming literary and performing artistic creation for children ever filmed about a relationship between an innocent child, oppressed and overwhelmed by more powerful mobs of cruel and sadistic (normal kids) middle-school bullies, is rescued in the nick of time by something JUST as innocent, natural and wonderful and otherworldly as the hero-child; a red toy ally just as different and alien to such a cold cruel world - here, an all red Koolhoven FK-55 somehow, almost as magically as can be - for real though, (psychologically really) shows itself to be our ever-present, reliable, wonderful rescuer - in all its simplicity, quite surprisingly and unexpectedly the final aircraft thing becomes a work of art. Further it was a labor of art, of love, of passion, like all artistic enterprise is. There's so much to freeflight, it is remarkably multi-faceted and phenomenal for so many reasons.

[@noclu4u384]

The old Dutch design has had its cobwebs dusted off . Very cool .

[@user-vp3sm9ci9w]

What a lovely glide at the end! Loved the music.

[@maxfliart]

Thx, Klaus. I've always enjoyed flying this model.

[@snort455]

maybe the most beautiful video I've seen on youtube

[@Hallo-Hallo]

Beautiful as always! Thanks! 👍😃

[@chattonlad9382]

That ditch is a magnet :-)

[@bryanwilhelm8341]

Tom: I t has been a delight to see and meet you at FAC events. Now you share your skills and techniques. I am so very grateful to meet and learn of your methods. Thank you BW

[@johnthemainguy9059]

Whew! Pretty close. Thanks for making me smile though. Lovely video, as usual.

[@snort455]

wonderful. its art and tecnology!

[@zebbocaster]

Beauty in motion.

[@ddrover2243]

Superb....nice job on the model....and the video...thanks!

[@paulsoler8986]

You make it look so easy! Fantastic!

[@flyingcloud4757]

Beautiful Tom

[@safa_abdul_rehman]

Very nice sir Happy modelling

[@glenncarter2126]

Incredible job👍

[@marcoaurelio-or9ku]

Maravilhoso! Verdadeira obra de arte! O aeromodelo, o vôo, as imagens, a música... tudo!

[@maxfliart]

Muito Obrigado!

[@randall4411]

Man that flies great ! Thanks for a great video .

[@awkward-stranger]

I didn't know such things existed! WOW Thank you

[@Rabbo4U]

My respect! Amazing plane.

[@patriciosilva1969]

Wow! Could you please describe the mechanism of the contrarotating prop?

[@maxfliart]

The unit is more closely shown about 25 seconds in on this film: kzbin.info/www/bejne/jafZoIuYoJ6Ceqs It works via the design of two prop shafts anchored into a series of stacked gears. One is a .032" wire, which goes thru the second shaft, which is a brass tube. The props are CA'd to these shafts. The designer had trouble in the past couple of years acquiring his stock to make more, so unfortunately they are no longer available. It's a beautiful system that runs very smoothly.

[@thesleuthinvestor2251]

Bravo!

[@fernandocarloszariz8845]

Tom. Este trabajo es increible!! Te felicito por la dedicacion, impresionante el vuelo!!! Fantastic video and work Tom!!! Saludos Fernando Zariz🇦🇷

[@SomeGuyInSandy]

There's the blast tube! Sweet flyer!

[@johnpp]

I've got a 1933 Model Aircraft Magazine with a plan for a scale MC72, with contra rotating props. Too far gone to get around to making it.

[@marianmm7034]

Veľmi pekné!

[@maxfliart]

Ďakujem mnohokrát.

[@mybluebelly]

Nice.

[@billsomrak]

I bet that CRPD sounds like an old Singer sewing machine when its in the air ... ha ha. I thought for sure it was going to get drenched on that last flight ... glad that wasn't so. Really a beautiful model. Thanks for sharing. Cheers.

[@maxfliart]

Yes it has quite a vroom vroom noise at launch. Love it.

[@silversurfer96790]

Incredibly 😍

[@sideshowbob5237]

There's some outstanding stuff on this channel. And what mean-minded person could possibly give this a thumbs-down. Explain yourself sir!

[@thomasnewton9818]

That's cool 😎 👍

[@robertpartsmade5832]

Poetry in motion …… Regards Partsmade 🇬🇧

[@ericboehm9457]

Amazing. I wish I could find one of those gear boxes. I drew up a Westland Wyvern years ago and I have yet to build it.

[@maxfliart]

I've had my eyes on a Short Sturgeon for awhile. Be wild to have a contra twin.

[@rogerbyarlay2985]

Eric - In Don Ross's second book 'Flying Models - Rubber, CO2, Electric, and Micro Radio Control', Chapter 10 - 'Gears and "WARP" Drives' Don writes about gearing and counter rotating systems. In that chapter Don writes that Roy Tiller showed him a system using Lego differentials. The Lego Item # that Don has listed in the book is Lego's Item #5229 "Gears and Differential". I did some searching online and found a number of different differential 'Lego' parts and purchased a couple of different ones (purchased both items from AliExpress). One of them I picked up is basically the #5229 set of gears (MOC Technical 29pcs Differential gear box kit) that I was planning on using with a project I was going to build later (Douglas A2D SkyShark). Although you can get just the differential I wanted to see if any of the other parts could be used. I have this set of parts in hand and they look very promising for counter rotating props. The cage is about 1-1/8" dia on the large end and 3/4" dia on the other. It is about 7/8' in length. The other one I ordered looks a little more compact. It is the 'MOC Ferrari Daytona SP3 High-Tech Gear Differential'. Since I do not have that one yet I don't know the size (it is currently in transit). Hopefully it will be a little more compact and will work. You might want to look into something like this for your Westland Wyvern.

[@Romin.777]

Marvelous :))

[@masteronone2079]

I have a theory that, irrigation ditches, sprinklers and (Particularly in my case) wire fences cause disturbances in the gravitational field suck balsa toward them.

[@maxfliart]

Yes. It's all very well documented, world-wide. Go figure.

[@aeromodeller1]

Trees do suck. They evapotranspirate water. Water vapor is less dense than air. The damp air rises, pulling air in from the sides. My planes seemed to be always seeking out the tallest trees to land in. Some kind of curse? Then I realized that when the are circling down from a height, the tallest trees are the first they will encounter.

[@Tadrjbs]

You are a pro Tom. There is a lot on Balsa Builders about tissue application troubles (what to use, won't shrink, etc.). I know you have videos of your covering process. I find and direct to your vids...Moses

[@riazhassan6570]

Wow! Beautiful. Would be interested to see how the contra-rotating mechanism works inside the nose block

[@maxfliart]

Check the link in the description for a closer view.

[@riazhassan6570]

@@maxfliart Thanks. Will do

[@richardbrowne1217]

What the heck happened? That model went way, way, way up in the sky! That was a long beautiful flight. Caught you and I by surprize!

[@erichanderson1491]

Free flight model planes can and do ride upward drafts of air commonly called thermals, that's probably what happened in the video. .

[@richardbrowne1217]

@@erichanderson1491 True.

[@billkuhl442]

I just cannot get over 19.45 grams without rubber., would expect the prop unit to weigh half of that. Very impressive like everything you do.

[@rickmidkiff9990]

Holy Crap

[@nealeunruh9409]

I second that

[@jacksnavely559]

Hey nice JOB all round 👍👍 I have an article on counter rotation prop drive for rubber and it's dated 1928. Has so.e other neat ideas in it also - Science and Mechanics

[@maxfliart]

Cool! Have u tried building it? The plan from '37 also showed a design, but it involved balsa tubes, and felt a bit clunky. I'm sure it wasn't all that efficient.

[@barkebaat]

Contra-rotating props on a rubber-powered model ? Since I cannot for the life of me imagine how that is possible, as far as I'm concerned it does not exist and this video does not exist. I have not seen it with my own eyes and that's why my headache is subsiding. Ahhhhh..... much better. Oh ! Look ! A video of kittens chasing tin foil :0

[@maxfliart]

Haha

[@guamflyer1]

Sure is Pretty....

[@bobeileen1]

....................and, it will be flying in heaven.......

[@aviatorsandastronauts]

Great meeting you at Geneseo this month. Love your videos! What is a source for blast tubes?

[@maxfliart]

Thx. I've used rocket body tubes, and also found some clear plastic tubes in various sizes via George B. at Volare. Not sure if he posts them on the website, listed in the film description.

[@aeromodeller1]

Aaahhh! Ditched in the ditch! Luckily no water. You sure that was a thermal? I think with that number of turns, that plane can get up that high all by itself.

[@maxfliart]

It's a funny bird. Sometimes at max winds, she flounders about at only 50' or so. I think there's a lot to be said about her position during flight, and if she's flying on the props, with the nose up just a bit too much. Or it could be the level of efficiency of the gears, if dust is holding them back a bit, or even the batch of rubber. But when she gets up as she did on the last flight, it felt like everything was in alignment. Then once the rubber faded, and she reached the sprinklers, she came down fast. Not surprised, since those props don't free-wheel, so it's Drag City.

[@prep0wer]

Contra rotating props create 25% power loss but also you can use ultra thin props because you have far less thrust bending.

[@jameswilliams1636]

👍🏻

[@michaelwhinnery164]

She scoots right along.

[@rickhall4318]

Tom, once again I was feeling defeated and you have my inventive juices flowing once more. Any chance I could get from you a drawing or more pictures of CRPD that you have? I need to finish something to get out of this terrible funk I'm in! Help me brother!

[@maxfliart]

Hi Rick. Hope that F/F is what u need right now. The CRPD unit is more closely shown about 25 seconds in on the film posted in the description above. It works via the design of two prop shafts anchored into a series of stacked gears. One is a .032" wire, which goes thru the second shaft, which is a brass tube. The props are CA'd to these shafts. The designer had trouble in the past couple of years acquiring his stock to make more, so unfortunately they are no longer available. It's a beautiful system that runs very smoothly.

[@modelleg]

Near to the Bugatti

[@randall4411]

Man that flies great ! Thanks for a great video .