Craig-RCU

Yes, the Kyosho F-86 does benifit from better designed ducting. The stock Kyosho F-86 has been clocked at 54 mph. With ducting and .15 CV-R engine I'm getting 82mph. Here is what I have done with the Kyosho F-86 http://www.geocities.com/cnhilgers/F86mods.html . I have also changed out the stock engine for the O.S. .15 CV-R car engine pictured at bottom.

Updated: Videos are outstripping geocities bandwidth. I'll post the new links soon.

The 82 mph speed in the video is close to the 90 mph exhaust velocities on the test stand. The exhuast outlet is at 100% FSA in these videos. If I narrow the outlet to 75% fsa I should theoreticly get exhaust airspeeds of 135 mph which would translate into 120 mph flight speeds in theory.

Actually, the performance with the stock engine was very similar in my fully ducted setup. The Kyosho fan may be too much for the CV-R to really shine. Although, the thrust to weight of the CV-R is 9.5 to one in the setup pictured below (CV-R weighs 5.75 oz with head fins cut down as shown) which is the same as an O.S. .91 installed in a BVM Viofan (1.5lb O.S. .91 produces 14lb thrust in the Viofan).

The CV-R and home made tuned pipe puts out 3.4 lbs thrust at 27.1k rpms on the test stand. Installed thrust is 75% of that or 2.6 lbs. The tuned pipe is 2 oz lighter than the stock engine's pipe and the CV-R does not have a pullstart so that saves another 2oz for an empty weight of 3.25 lbs as opposed to the stock setup's 3.5 lb empty weight.

The lesson here... efficient ducting really pays off.

Craig-RCU

Geocities apparently doesn't like large bandwidth web pages. I just posted this same thread on ezone and I've exceeded bandwidth already.

I'll find another place to post the videos. And list the alternate site here asap. Any ideas where I could post the videos would be helpful.

Thanks, Craig

Craig-RCU

OK., lets try this again with the videos.

Start up
http://www.usfamily.net/web/craighilgers/f86start.zip

Take off
http://www.usfamily.net/web/craighilgers/f86takeoff.zip

82mph pass
http://www.usfamily.net/web/craighilgers/f8682mph.zip

landing
http://www.usfamily.net/web/craighilgers/f86landing.zip

Terry Holston

My Feedback: (1)

Good job,Now how about a set of those ducts?

littlepiston

My Feedback: (12)

dam thats prety mo@#$@#@# FAST!!!!!!!!!!!!!!!!!!!!!!!
how ere gan i cat this ducting Craig i have been following your work for a wile now and finaly you have proof now let me have what ever you fed that little beast

Woketman

My Feedback: (6)

I have only seen one of these fly in person. It was at Superman '01 and it was anemic at best. This video shows easily ten times the performance. Great job Craig!

littlepiston

My Feedback: (12)

Kyosho fan or wemotec fan?

Craig-RCU

Thanks all for the kind words. The hard work has finally paid off. I'm really happy with the performance. I don't think I want to get into producing ducting though. Maybe if I show the video to Kyosho, they will want to buy the molds from me or something. I'll have to see what happens.

littlepiston,
All my flights with the Kyosho F-86 were with the Kyosho rotor since it tested slightly better static thrust on the stand. Fuel for all flights was Omega 30% high performance heli. The Midifan might produce better top speeds though since the hub is exactly the same diameter as the engine mount of the Kyosho shroud. The Wemotec just appears to be made for the Kyosho shroud and more aerodynamic than the Kyosho rotor if that makes any sence to you. I am very tired right now so, I'm not sure if I'm getting my thoughs across.

littlepiston

My Feedback: (12)

[ I don't think I want to get into producing ducting though.


all that convincing and yet you keep the seccret sheehs
come on man make me one

lov2flyrc

My Feedback: (24)

Nice work craig, you really have brought that slug alive!! If it performed that way out of the box they would be pressed to keep them on the shelf!

Congrats!
Todd

KevinBarr

My Feedback: (27)

Craig,

Great job. I can attest to seeing this plane first hand, it flies extremely well. I saw a Kyosho F-86 fly at Superman '01 and it was horrible.

The mods Craig did really give it DF performance...

Kevin Barr

Craig-RCU

littlepiston,
Sorry, producing ducting would be just too much like work and would ruin the fun of the hobby for me. I am more the R&D type rather than the production manager type. There should be enough pictures on my website to help you make your own ducting. If you have scratchbuilt your own aircraft from 3-views before it should be no problem. I'll take more pictures if anything is not clear enough.

Now that my Sabre has proven itself as a strong flyer, I can sacrifice a little static thrust and reduce the exhaust outlet some for greater speeds. I have an idea for a simple, variable exhaust outlet that I'm going to try next. Retracts are also a must for higher speeds. Robart and Greatplanes make some nice small retracts that I'd like to try.

Thanks, Todd and Kevin for the support.
I am going to send the videos to Kyosho's product improvement department. They didn't reply the first time I sent them the link to my still images web page. Maybe the videos will convince them of the benefits of my setup.

If Kyosho would produce a "Hop up package" or something that would keep their Sabre selling. It is definitely a good platform for better power setups. I think that Kyosho has found a nitche here with sub .25 size ducted fan models. Good .15 and .21 size d/f power plants (in the form of car engines) are available at half the price of .45 and .91 size d/f engines. As far as I understand, .45 size jets never got very popular because .45 D/F engines are not substancially cheaper than .91 size engines. So, why pay 90% the cost of a .91 size d/f engine and then not just go the extra 10%.

Good performing small ducted fan models can give the same ducted fan speed thrill that .91 size models give but at a fraction of the cost. Though you'll never take a Top Gun or Superman award away from a .91 size jet. My 3' long Sabre moving at 82 mph gives the same perception of speed that a 6' jet moving at 164mph gives. But, I'm probalby preaching to the chior here. Just my .02. With the cancellation of the Kyosho electric F-16 and the lackluster performance of the stock Kyosho F-86, I see the demise of small Kyosho jet models if somthing doesn't give. Such is life.

Daren Savage

My Feedback: (6)

Depending on the weight of your Sabre, you might look at Springaire's 600 series. Dan and I each have a set on our Flankers (5.75 lbs. RTF), and they work great. Top quality, all-aluminium units.

Daren

Craig-RCU

Daren,
Thanks, I will check those out. My Sabre is 3.25 lbs empty maybe around 3.6lbs with 6oz fuel. With that intake ducting I'm going to need a really low profile nose gear setup. The Robart and Greatplane nosegears are too tall to fit under the inlet ducting. I may have to scratch build the nosegear. Full scale F-16's have a similar nosegear problem, so I'd probably design the nosegear like an F-16's.

littlepiston

My Feedback: (12)

Craig
, i got my Kyosho back .!Woo Hoo! well who cares any way what altitude are you flying at? im at 3600, 3500?

Craig-RCU

littlepiston,
I'm at about 700' here in Minneapolis MN. Where did you get your Kyosho back from?

littlepiston

My Feedback: (12)

well my budy Larry seei osld it to this guy in siminole and the he traded it to larry and he tryed to sell it ,,,but Kyosho f86 sabre has a bad name right now,,, so it did not sell ,,,GOOD THING!!!! well i got it back WOOHOO!!!!

t33jetman

My Feedback: (1)

Craig,

I tip my hat off to you man, you knew you did a great job with the duct work to make you plane a reall performer.

Since you are not going to market the duct work and the company is not going to make it an upgrade kit unless it is profitable, it just won't happen.

The mods that you saw at Superman made it fly better than it was just straight out of the box( now that my motor is broken in, I will take on any other same plane with my mods any day) and the cost is nothing more than a small plastic sheet glued in for a thrust tube. I just flew it for the first time this year and it reall screams now.

To all that asked about the tail opening, please do not close it down to 21/2 in. this will not work for good take off power, trust me I just found out and changed it back to the old opening with the thrust tube now in place. cheap fix, for a simple go fly plane to warm up for your go fast plane.

RobH

I appologize for posting on such an old thread. I'm looking to couple an RC Nitro Car engine (.21 sized) to a ducted fan blade (not whole DF unit -- just the blade). I'm looking for a blade that won't EXPLODE if the engine gets up in the 35,000 ish RPM range.

I noticed the OS .15 CV-R is rated at a max of 31,000 rpm. If you're plane goes that fast, you must be turning that ducted fan blade pretty fast! Are you using the stock ducted fan blade? If not, what are you using?

I'd like to turn my old .21 buggy engine into a "blower engine" for a homemade hovercraft project.

This is my Ducted Fan blade thread in the "Jet" Forum, if anyone can help:

http://www.rcuniverse.com/forum/Moun...1339325/tm.htm

Thanks,
RobH

DMehalko

My Feedback: (42)

I had the same idea. I rally like the looks of that plane but hear it has no power.

Maybe I can buy the plane without the engine and put like a .21 car engine in it.


Has anyone done this?




David

mac1

Craig,

I have logged 10 flights on my Sabre, i have built it exactly as per the manual instructions and used 25% Nitro, i flew it with the rich setting initial to break the stock engine properly and it was not easy but no damage or stalls, after leaning the engine to it's optimum setting the Sabre flew like a dream, it is fast and the rolls and loops where great, no cheater holes at all just like the manual instructions.
I wanted intentionally to do that to see what kyosho are trying to prove, here in Dubai i believe i am the 2nd person to have flown the Sabre as it has a bad reputation, but after my display the other day at the Dubai R/C club the Sabre had lots of admirers.
I have fully read your modifications with the CVR engine, however i do not want to go that far with the Viofan from BVM or to even try to copy the design, i would like your opinion on the following:
My plan is to install the OS.15 CVR pull start car engine but change the heat sink head and carburetor with the stock engine and fit on the supplied ducted fan unit, i have compared the CC, Bore, Stroke, Weight, and mounting flange's between the stock engine and the CVR and to me it looks the transition can be made, the engine specifications are available at www.towerhobbies.com, although the certified replacement engine as per tower hobbies is the OS.15 CVX pull start which is only .18 BHP more than the stock engine where the CVR punches 1.2 BHP.
A: do you think the CVR will fit.
B: do you think the fan will take the power delivered by the CVR.
C: do you advise installing the CVX or the CVR provided i don't want to do any modifications on the fuselage. i.e. no cheater holes etc.

Thanks
Tarek

watt_the!

The following chart compares the benchmark rk720 with the kyosho rotor.

The os 15 cvr is included from dyno results obtained from nitro rc.com

the kyosho fan is 44% efficient. The rk720 is 58% efficient.

Even that being said, the kress fan will allow the os 15 to get to 24k or so, yielding nearly 3.8 lb.

this being compared to the 27.1k and 3.4lb obtained by the kyosho fan due to it's lower fan loading and lower efficiency.

watt_the!

i thought i'd add the sirio 0.15 to the fray.

this little powerhouse will take the rk720 to 28k+ and 5lb + thrust.

it'll take the kyosho fan to 30k for 4lb+ thrust.

watt_the!

please post the material specs for the fan you propose to use. Then it's just a matter of doing a stress/strain calc to determine whether the fan will fail. I highly doubt that it will explode. Even the softest nylon 6/6 wont explode unless you are doing 50k revs.

it'ss stretch though..which i would think would be your biggest concern. As soon as it stretches around the shaft, then you get slippage.

Polyamide (nylon /glass) is the way to go. it wont stretch as much and will spin higher without "exploding"..lol. (they dont explode).

you wont get any fan spinning faster than 33k anyway, which means that nothing's going to explode or even stretch. We've tested many and the biggest issue is correctly matching the power from the engine to the power absorbed by the fan.
For instance, the hyper 21 8 port is rated at 38k and 2.6 bhp. It wont go past 25k on the rk720 because the fan absorbs all of the available power from the hyper at 25k.

KLH0324

I recently had the chance to purchase an unassembled F-86F Sabre kit that didn't come with wings or ailerons. Does anyone know of a place I could purchase these items from? I have already sent Kyosho customer support an email asking the question. Thanks for any help.