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-   -   Mini F-16 vintage project consideration (https://www.rcuniverse.com/forum/1-2-1-8-airplanes-70/10872728-mini-f-16-vintage-project-consideration.html)

RickP 12-23-2011 05:31 AM

Mini F-16 vintage project consideration
 
1 Attachment(s)
Hey Guys,
You have been very helpful on an old thread I dug up and asked a few questions on. Obviously this project has become a little more to me than just a few casual questions, so I thought I should start a thread here. Your expertise on the 1/2 A stuff seems spot on.

Background - skip to the bottom if you want to get to the thread -

When I was 11 years old (1980) and budding RC enthusiast, I was learning to fly. I was riding my bicycle 7 miles to the LHS almost all the time. The 1980 AMA magazine featured a build article of a Mini F-16 1/2A ducted fan and I was enamored. I wanted to build and fly that thing so bad. Anyway the good people at the LHS kept steering me away from the Axifo RK-049 and over to the K&B .40's and Falcon 56's. Thankfully they did - I have been flying RC ever since. I would occasionally buy some sheet plywood thinking I could start making the duct and they would look at me through a crooked eye and ask what I was up to and I'd say nothing LOL. They knew and steered me right.

So in the last AMA issue they featured a small retro article on this airplane and I couldn't help but feeling as enamored as I was 20plus years ago. The reality of this project is that the technology is ancient, parts obsolete, and the plane probably didn't fly that well or have much power. Now the obvious answer is to just put an EDF in it, but if I'm going to do that I might as well just buy a foam one. It will probably be a fraction of the cost and fly so much better. I might just do that anyway too.

With all that said, the object of this undertaking, should I choose to do so, would be to make it 1/2A nitro ducted fan using the original plans. I'm not against hopping it up maybe say an .090 instead of a .049, current electronics and maybe building materials to shave some weight off (carbon fiber etc.), it needs to fly reasonably well so I can enjoy it.

The Thread - on to the issues -

To tackle this project I need to come up with a power plant. All the Nitro Ducted fan units are obsolete and hard to find. The Axiflo was one of the first and as such the ones which came later (Kamdam ect). performed much better. After a week or so of consideration I think the best course of action is to just build my own. After all those kits were not all that complicated and if you can find one now it’s going to be on the order of $120 without the motor. The problem is the FAN. I can't build that. I've got to find one somewhere. I found a guy who has several Axiflo .049 and .21 size fans, I'm going to try and scoop those up (see pic attached).

I have the plans and instructions for everything so I'm sure we can create something.

The next step is to tackle the power plant. Original engine was the Tee Dee .049, but I am thinking Tee Dee .090. However, I have no idea how that is going to work with the fan. maybe it works well with the .049 but surely just swapping in a .090 is likely going to need a different size FAN.

So please give me your questions and comments. Is this a waste of time? What do you think about the power plants? What motor should I use? NIB cox motors can be had, but is there a modern equivalent I should consider?

Once we get past these critical issues then the real fun stuff can start. For instance, the plans show a flat bottom wing. Really? Can we do better and make it go faster?....

Kind regards,
Rick

combatpigg 12-23-2011 06:06 AM

RE: Mini F-16 vintage project consideration
 
Flat bottom wings have served me well with 1/2A speed planes.
If the plane is small enough and clean enough, make the wing as thin as structural limits allow and you will find that the airfoil isn't rocket science.
The important thing is to make it smooth and flowing with no dips, ridges, etc..
Place the high point as far back as you like, just trust your eyes for what looks clean.

If you want full aerobatics, then go with something else..but for all out speed on 1/2A models, flat bottom airfoils that are 1/4" thick with an average chord of 5 or 6 inches work very well.

gkamysz 12-23-2011 08:42 AM

RE: Mini F-16 vintage project consideration
 

ORIGINAL: RickP

The next step is to tackle the power plant. Original engine was the Tee Dee .049, but I am thinking Tee Dee .090. However, I have no idea how that is going to work with the fan. maybe it works well with the .049 but surely just swapping in a .090 is likely going to need a different size FAN.

So please give me your questions and comments. Is this a waste of time? What do you think about the power plants? What motor should I use? NIB cox motors can be had, but is there a modern equivalent I should consider?

Once we get past these critical issues then the real fun stuff can start. For instance, the plans show a flat bottom wing. Really? Can we do better and make it go faster?....

A fan or prop with twice the power input will only turn 2^(1/3) or 26% faster. I don't know what the fan runs with a TD049, but if 26% faster is still within the RPM range of a TD .09 I'd go with it. The issues might be more finding an engine that can handle the RPM and make the power required. I'm not sure that a TD .09 makes twice the power of a TD.049. Since RPM will increase 26% the speed will also only increase this much. Compared to the .049 this should be very noticeable, but still relatively speaking slow.

I wouldn't worry about the wing. That is not going to be limiting your speed at all in this case. The airframe is not sleek, the fan is much oversize to the airframe. Speed will be limited by the thrust and velocity available from the fan.

If it flew in 1980 it will fly today. I'd save weight with lighter radio gear, but wouldn't change anything except the power plant. If the power plant gets heavy, you might have to reinforce things. Take it for what it is. It's a simple design and will not be fast. I have this plan and have thought about building it, but having looked at the numbers I've lost interest without redesigning it for a smaller optimized fan unit. That means drawing a new plan. I also have Ziroli's plan for an He-162 for the Axi-flo fan. That would be much easier to modify to a smaller fan, so chances are it would be built before anything else. Regardless, my list is so long it will be a while before any of that happens.

Greg

RickP 12-23-2011 01:44 PM

RE: Mini F-16 vintage project consideration
 
Okay Guys,
I am going to get my hands on those spare fans and see if I can make them work.

Now what about the size difference of the Tee Dee 049 and Tee Dee .090. is there any way I can get some drawings of those guys on the web so I can start to lay this out?

Kind regards,
Rick

Rubbernecker 12-23-2011 02:55 PM

RE: Mini F-16 vintage project consideration
 
Sent you a pm.

John

RickP 12-23-2011 04:55 PM

RE: Mini F-16 vintage project consideration
 
Are there any modern engines I should be considering?
RP

Tee Bee 12-23-2011 05:54 PM

RE: Mini F-16 vintage project consideration
 
I admire your effort and desire so far to revive an older design like this and breathe life into it. Yes, modern EDFs are more efficient, easier to deal with, and readily available but it's a hobby and you should enjoy it as you please. I definitely understand your desire to power it with a glow engine. Some of my favorite models to fly were built from 30 year old plans. They may not be as efficient as some of the modern stuff but that often matters little to me. Good luck with your project.

Jaspur_x 12-23-2011 05:56 PM

RE: Mini F-16 vintage project consideration
 
I say there is only 1 way to answer the question that you have had all these years is to finally build it. The modern radio equipment of todat will ensure that it is lighter which should only help the flight characteritics out.

I have always wanted to do a build like this but it remains on the back burner. I have tinkered around with a few small fans for the 020 sizes, but that was just tinkering around without spending any money on a variety of fans therefore poor results.

I am watching to see whst you come up with. My teedee 049 awaits some decent findings.

I think that the teedee09 was effective mostly due to swinging a larger prop than the 049,but the 049 actually was higher rpm`s than the 09 if I recall correctly. If you get a fan that would produce good thrust and a good fit for the model but the teedee049 is just not powerful enough to hit high rpm`s due to too much load imposed by the fan, try the 09 which handles a larger load.

combatpigg 12-23-2011 06:59 PM

RE: Mini F-16 vintage project consideration
 
The Fan Trainer with a Kustom Kraftsmanship modified TD .049 and a cut down 5x3 prop inside the shroud was able to fly reasonably well....but looked kind of cartoonish with the sound effects of a 25,000 rpm engine inside a plane that was going maybe 40 mph.

It was also a pain to engage the engine with any kind of a starter to crank the engine.

High rpm engines trade torque for high rpm horsepower. Electric motors don't need to, they can develope max torque right from the get go and still spool up into high rpms. This is one reason why it makes more sense to go electric here.

There isn't any substitute for cubic inches with ducted fan models. The bigger models with 1 cubic inch engines had performance that was almost worth the expense and effort that went into making them go.

Depending on your expectations, it might be best to sacrifice a cheap TD to one of these "Easy Bake Oven" projects than it would to spend a couple hundred bucks on a world class small displacement engine and then end up roasting it without seeing anything worth watching.

RickP 12-23-2011 09:11 PM

RE: Mini F-16 vintage project consideration
 


ORIGINAL: combatpigg
This is one reason why it makes more sense to go electric here.
Hello,
Well common sense would have left this topic in 1981. I am reliving a child hood experience here. I've got a EDF on order shortly here. This thread will require some grey matter ;)
RP

RickP 12-24-2011 02:12 PM

RE: Mini F-16 vintage project consideration
 
Is a Tee Dee .090 worth $150?
RP
PS that is NIB

combatpigg 12-24-2011 03:12 PM

RE: Mini F-16 vintage project consideration
 
Do a search on Cyclon engines, Foras, Rossis, Nelson .15s..Profis...

Even though high rpm model engines are gutless you should be able to remove blade area on EDF fans until the engine is revving where it should. It's always a juggling match between diameter, blade area, blade thickness and pitch. Plastic props can be shaved / scraped with an Xacto blade. High timed engines hit a wall if you slightly overload them...they all have an invisible line you can not cross with load.

DeviousDave 12-24-2011 11:02 PM

RE: Mini F-16 vintage project consideration
 


ORIGINAL: RickP

Are there any modern engines I should be considering?
RP

I'd be looking at a Norvel AME .061. It will fit where a TD will and makes a ton more power

Jaspur_x 12-25-2011 04:22 AM

RE: Mini F-16 vintage project consideration
 


ORIGINAL: RickP



ORIGINAL: combatpigg
This is one reason why it makes more sense to go electric here.
Hello,
Well common sense would have left this topic in 1981. I am reliving a child hood experience here. I've got a EDF on order shortly here. This thread will require some grey matter ;)
RP
Exactly!! And plz do a build thread on it for those of us curious about the same for all these years, even if you never go beyond the tinkering stage ; there is a "nostalgia" factor here that keeps the remaining kid in "us" going on the old ideas we never got to explore in our youth. Or just keep this thread rolling with your progress.

RickP 12-25-2011 07:18 PM

RE: Mini F-16 vintage project consideration
 


ORIGINAL: Jaspur_x



ORIGINAL: RickP



ORIGINAL: combatpigg
This is one reason why it makes more sense to go electric here.
Hello,
Well common sense would have left this topic in 1981. I am reliving a child hood experience here. I've got a EDF on order shortly here. This thread will require some grey matter ;)
RP
Exactly!! And plz do a build thread on it for those of us curious about the same for all these years, even if you never go beyond the tinkering stage ; there is a ''nostalgia'' factor here that keeps the remaining kid in ''us'' going on the old ideas we never got to explore in our youth. Or just keep this thread rolling with your progress.
Hello All,
Well in case you didn't notice - thread started here ;) you know you are helping me hone in on this thing. Some of my research has pointed me towards Picco .12's , but those are modern high performance RC car engines and I'd have to modify the head etc. I quickly started to loose interest. It's not about hi performance (although I would like superior performance for the time frame). I think it's about "nostalgia" as well. That being said I am loosing interest in anything beyond a Tee Dee .090 unfortunately. Something about those motors drawing me back. That's all I had when I started and I can still get them NIB. Go figure....

This is the thread so keep posted. The decision is coming quickly. If I can't do this with a vintage motor then i'm going to bail out. I can buy a foam edf and be done with it already. The journey is where the excitement is and I think if i can find a motor and fan combination I can decide on the decision will be made.

I am buying a bunch of vintage FANs from which I'll try to match up to an appropriate power plant. I do not work that fast so please bear with me. I'll keep you posted.
Kind regards,
Rick

Jaspur_x 12-25-2011 10:29 PM

RE: Mini F-16 vintage project consideration
 


congrats on your decisions,vintage,nostalgis is where I would consider the motivation to lie for this project. I always wanted one myself,and it hasremained "in the rear with the gear" file of projectsall these years.

there are plenty of DF units available for conversion from electric to glow. The pitch, length of the actual blades, and diameter all are considerations to get the optimal performance from a teedee049 or 09.
There may be a DF on the market that is more effecive than the originalthat was used back in theday for this type of project is what I am geting at. HobbyKing has a bunch i have been thinking of; a lot of them are available without the electric motor,unassembled at a low price.

I`m keeping posted for my future similar project build.

I tried a few diferent fans available for a smaller project as I posted previously. They were newer designs than this build,produced plenty of thrust considering,while they overloaded the 020`s,I just never got back to it once I used all the fans I had on hand.

but, I have teedee 049`s and will get a 09 if this works ot best in your build.

With the tiny radio gear,and the variety of DF`s available, a blast from the past like this is very possible,and could be much more effective thanback in the day for a decent flying plane that will bring much satisfaction of this old "someday" project.
I have too many on my list to do at the moment or i would be pitching in finding a decent powerplant. I may throw in helping find a decent fan for the teedee049next month;but don`t wait on me.</p>

RickP 12-27-2011 11:08 AM

RE: Mini F-16 vintage project consideration
 
I don't know now. I wish I could find some solid specifications on the Tee Dees. Does anyone know what the practical RPM range is for these motors? I was just surfing around and the RC Buggie / car motors are from 5K to 30K for about what I was going to spend on a new TD .090. Mainly you can get the OS .12 for around $160 http://www.osengines.com/engines/engine-specs.html

It would be real nice if could get a feel for the sizes of the .049 and .090 engines as I now have full size plans and can lay it out. If anyone can help with this I'd greatly appreciate it. I'd even consider buying dead engines if you have some parts laying around.
Kind regards,
Rick

gkamysz 12-27-2011 12:02 PM

RE: Mini F-16 vintage project consideration
 
I thought I had a scan of the RK-709 manual, but can't find it. The RK-709 was designed for the TD .09. I think it's the same diameter as the older Axi-flo .049.

RickP 12-27-2011 01:17 PM

RE: Mini F-16 vintage project consideration
 
Hi Greg,
I scored the plans and manual with plenty of pictures for the RK-049. So if they are that similar it should be a peice of cake. I found someone who has several fans of the 049 and 709 variety. I'm hoping I can get him to part with them soon then I can start thinking about how I am going to lay it out.

Looking at modern nitro motors I see the airplane engines do not rev much over 18K and I'm thinking that's all I'd get out of a Tee Dee anyway. I see that depending on use (nitro buggy engines) will operate up to 30K and if you really want to foot the bill at 2X the cost you can get up to 40K.

So I haven't decided yet, but this project is looking marginal at best using a Cox motor. More attractive using a modern .12, but I'm scared the fan might not hold up well. I have no data but I have to assume that the DF manufacturers in the 80's designed the impellers to be effective for RPM's at the time. I think bumping those fans up to a modern nitro might yeild better results then if I took a modern EDF fan and bumped it down to the nitro motor. Just have to hope that it won't grenade on me.

Still thinking...
Rick

gkamysz 12-27-2011 02:06 PM

RE: Mini F-16 vintage project consideration
 
RPM is one thing and power is another. An engine has a torque output curve and a fan or prop has a torque required curve. Matching the torque output of the engine near peak HP to the fan torque required curve is the trick. I found only one video on youtube of an RK-709. It looked OK. If I wanted to fly it I'd just build it with the Cox .09 and the 709 fan assuming it fits. Later If I thought I could do better and had interest I'd look at other options. When Violett did his fans he knew what he was doing. In the end he was essentially building his own engine to fit his fan.

Rick your F-16 going to be cool even with a puny TD.09, just be cause you'll have built and flown one while we've just dreamed about it.

Do the RK-049 papers have a power curve in them? I've looked them over at one point but can't remember.

RickP 12-28-2011 04:51 AM

RE: Mini F-16 vintage project consideration
 
1 Attachment(s)


Do the RK-049 papers have a power curve in them? I've looked them over at one point but can't remember.
LOL,
Greg, you have torque curves on the brain! Here's the plans. No, no torque curve :-(
RP

gkamysz 12-28-2011 09:23 AM

RE: Mini F-16 vintage project consideration
 

ORIGINAL: RickP
LOL,
Greg, you have torque curves on the brain! Here's the plans. No, no torque curve :-(
RP

Hi I'm Greg, and I'm an enginoholic (dynaholic?). It's also stuff I work with on a regular basis. I don't have any Kress stuff anymore. I designed and prototyped a 50mm EDF unit in 2000, but never put it into production. I'm working on a new spindle and fourth axis for my small milling machine. When that's done I hope to make a few EDF units. I'll see how things look after that.

jonastecknare 12-28-2011 12:39 PM

RE: Mini F-16 vintage project consideration
 
Thanks Rick! I have been looking for that one! I just might scratchbuild one of those! Thanks again.
Jonas

ORIGINAL: RickP



Do the RK-049 papers have a power curve in them? I've looked them over at one point but can't remember.
LOL,
Greg, you have torque curves on the brain! Here's the plans. No, no torque curve :-(
RP


RickP 12-28-2011 01:26 PM

RE: Mini F-16 vintage project consideration
 
Hey Guys,
I just purchased a bunch of stuff I found from a guy on Ebay. I got an .049 fan n shroud (make?? I donno) and several RK-709 Fans. There are also some RK-720 parts, but I figured I'd just take the whole package. I think he also has the plans / instructions for the RK-709. He seemed to have quite a bit of knowledge about this stuff from back in the day, so maybe he's a source I can continue to tap on.

My plan or thinking at the moment is to basically scratch build my fan using the RK-049 plans and RK-709 Fan rotor and Tee Dee .090. I have found several threads where people have flown this Mini F-16 and it was claimed be the best flying of the 3 popular models of the period. That is encuraging. Maybe tanking up with the .090 will give it just a little more flyability? I am banking on the fact that someone (Kress???) spent enough time matching the .090 to the fan used in the RK-709. Without the dyno's and test equipment this is the most reasonable decision I can make with regards to this build.

But get this. He was also suggesting to me that I go with one of these motors:

http://www.rcdeal.com/modules/stores...m.php?item=140

I could have bought three of them for the price of the fan parts I just bought. What do you guys think of this? 35K RPM can that be real?

Thanks for the support

Jon, No problem, but scratch building one of these is going to hard without the fan. maybe i can take some detailed measurements (CMM???) and we can talk about modifying them?

RickP

gkamysz 12-28-2011 05:48 PM

RE: Mini F-16 vintage project consideration
 
I do think that the RK-709 and the TD .09 will be great together. Kress also knew what he was doing with his fan designs, but the assembly and quality was quite as high as it could have been in my opinion.

Those P-Zero do turn 35kRPM and faster, but this is what I was getting at. How much torque does it make and what does the curve look like? I have a few of these Picco's, but haven't done anything yet. A few guys that ran them did get reasonable power, but cranks broke. http://www.rcuniverse.com/forum/m_83..._1/key_/tm.htm I think it's about 120 watts at 28kRPM, but with the RK-709 the engine would run much slower and make less power.


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