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Nov 01, 2014, 08:34 PM
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70 ragtop's Avatar
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Thanks Ron
Right back at ya....still waiting to see light under those big F-18 wheels
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Nov 01, 2014, 09:57 PM
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A10pilot's Avatar
ragtop:
With regards to the F-14 and reworking the pivot mechanism, there are a couple of really good threads on RCU where some of the guys are modding their Fly Eagle F-14's. Take a look I the jet forums.

Ed
Nov 02, 2014, 06:48 PM
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70 ragtop's Avatar
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Stab pivot came out good, but once I took the blocks out from under the wingbox, wingbox tipped pretty good to the left. Need to get that sorted out.

Pulled one of the inlets out today. Needed to get a good look at the front on the plane, the duct, and do some thinking. Was able to get some good measurements.

While there is no doubt Dynamaxs worked in this plane, I really want to keep weight down, and thought the duct/FSA ratio a little small, still do. The inlet area is pretty consistent until the last few inches, where is balloons up to fit the Dynamax. Put three cuts in the inlet, and trial fit it to an old Viojet, and it looks pretty good

Inlet area is roughly 13.86 sq in

Not sure about these numbers, but I believe a Dynamax has a FSA of 15.96 sq in, ducts would be 87%

The Viojet, and the Jetfan 120 are almost the same. Believe the Viojet is 14.02 sq inches, an the Jetfan is 14.11 sq in. Duct FSA of 98.86% and 98.23% respectively. That is close enough for me

My plan is to tie the front of the plane together just like DCU/JM intended, by using the inlets to lock it all together. Inlets fit snug to the lower sides of fuse, and under the wingbox

Will resize the inlet duct to fit the JF 120. Will need to tape duct once it's back inside the plane, and slide it forward as it's glassed.
Wrap, the ducts, and add some extra carbon tape where duct passes under wingbox. Want to make that area nice and strong. May need to add a little wood to wing box to make up for smaller duct diameter, that's right around the area the duct ballooned up
Last edited by 70 ragtop; Nov 02, 2014 at 10:45 PM.
Nov 05, 2014, 12:15 AM
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So YOU got this kit! I was wondering who was going to get it, i was trying to come up with the cash, but decided to just put that money towards the big one in my garage.

In regards to the pivot bar, i would modify it slightly and do like Yellow does on their Big F18, its basically a hard balsa block with a hole in the middle and a slot for a rod that goes through the pivot. The whole thing is then epoxied into the stab and thd root capled with a balsa root block. Simple and effective!
My stab mechanism and pivot rod is Really over engineered with the 1/2" solid titanium pivot rod.

In regards to the fuse, you really dont need a whole bunch back there. If you got some 3/16" contest grade balsa and put a layer of 2oz glass on either side, you'll have what you need to stiffen it up. Just run some longerons down the corners of the tunnel on the bottom to the top fuse skin. Just be sure to swiss cheese it with some diagonal trusses like a bridge.

If i can ever get out from under this Pancake build and get the Ta152 done, ill be able to knock out the F14 fairly quickly.
Nov 05, 2014, 11:05 PM
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70 ragtop's Avatar
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Yup, it was me....wife can go another winter on old tires, kids don't need new shoes Price came way down, and I still broke my toy limit on this one

Your money is better spent finishing up your big F-14!
That's an amazing project, looking forward to seeing your next installments

Planning on trying depron, skinned with carbon. Will do some materials testing first, but if results are good, should fill the bill and be very strong and light.
One stiffener running up insides of each tunnel in beaver tail area, tying upper and lower skins, effectively turning one big open area, into three smaller four sided areas. Will extend rear hatch ply into a former to complete the box

Pieces are dimensionally small, but should really stiffen up the tail section. Will likely add a small former on the back side of stab pivot block that ties into rudder post. Vertical only has one small spar, rudder post does not extend inside fuse, nor connect to anything but the skin. See that being a problem, and was reported as such on Hawaii Jet site

I was thinking same thing on pivot blocks, only difference, there is no carbon between cores and skins like todays kits. Its like an old Yellow kit. Have become too addicted to carbon....can't live without it now....
Nov 06, 2014, 06:29 PM
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Found a little time to mess with ducts today. Decided to do two piece inlet duct, as I can fit the halves in thru the hatch. Otherwise, ducts need to be cut down the middle, rolled and slipped out the nozzle. Of coarse this means they need to be retaped in the plane....which would be a pain

I like the idea of the Jet Fan 90, but I also like the static thrust numbers for the 120. Have been searching thru threads, and quite a few of these flew on Dynamax, or 13-15lb turbines. The turbines had to have been 30#+ lbs. With a pair of 120s plane would be roughly 26# with 28-30 lbs thrust. JF90 would be 24-25 lbs with 22# thrust

No doubt the 90 has a higher Eflux, and the 120 has more volume of air, but I don't think this plane would need the much volume to push it around in a spirted fashion, it is not a big plane

I'm having trouble understanding once the plane is in the air, flying at say 100-110 MPH, which fan would be more efficient???

Anyways, left duct has a plug for the Jet Fan 90, right side just modifying old duct to fit 120, and moving fan forward a few inches
Last edited by 70 ragtop; Nov 07, 2014 at 12:53 AM.
Nov 06, 2014, 06:34 PM
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Based on what i saw with the Horten and a 30# airplane on JF90's, if it was me, i would go with 120's on 10S and use the weight difference in 12s and 10s lipos to add more capacity to a 10S setup.
Nov 06, 2014, 08:43 PM
Dont forget the velcro straps
corsair nut's Avatar
yeah i vote 120s
Nov 06, 2014, 09:37 PM
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gunradd's Avatar
you need to run each fan with the ducting on it then see if it makes since to use the bigger fan. You might be loosing allot with the bigger fan with small inlets.
Nov 06, 2014, 10:59 PM
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No way 120's this thing is just not big enough.... If it were mine I would put a pair of SM100 or tj100's in it. The TJ 100 in long ducting sounds pretty nice despite being a 4 blade rotor. In my A7 in sounded nice and flew great on 10s 4000. This jet is just not big enough for twin 120's!
Nov 07, 2014, 12:39 AM
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70 ragtop's Avatar
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No consensus here

This thing is a lot smaller than your Horten. It might look big in pictures, but it's not. It's just heavy due to being an F-14 (heavy gear, jack screw, pivot brackets, ect) I like your idea of running the 120s on 10S. Guessing 12ish lbs static using the 590s, less battery weight, less amps, still have lots of fan air volume, wonder how it would be on top end?

I agree that running both fans with full ducting would be a good exercise. In all honesty, its going to come down to the takeoff roll. If the 90s can accelerate it quickly on short grass, they're in, if they can't they're out

I guess I'm just stuck on the performance from the videos of the old Violett/JHH planes running the 90. CN's F-86, Rainer's F-86 and Aggressor, ect. When I look at the fans side by side, there a big difference

For an idea of scale, bench top is a 80x36 door panel, and that's a BVM F-16 next to it. You can see, it's not very big. The fan area looks big as Tomcats had fat engines to start with, but this plane was designed around the Dynamax. Actually has a custom mounting brackets because the stock Dynamax mount tabs wouldn't fit

After looking at overall size shots, let me know if you have the same thoughts??
Last edited by 70 ragtop; Nov 07, 2014 at 12:50 AM.
Nov 07, 2014, 12:50 AM
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skyhawk's Avatar
120's.

Especially if flying off grass. I said it before - this is a proven well preforming winner on the 127 fans. I have flown it before (did not build it - it was my friends) I can understand going to 120's. Maybe 110's - but 90's are going to be a high powered 3 min dog. A larger fan will do a job more efficiently every time.

Here's another thought...My Byron F-16 is 13 lbs RTF with 10s and a byrofan, By some of the reasoning here I could stick a Jetfan 90 in it (higher cell count and drop some weight from the powerplant) and come out about 1:1. There is no way a 90 would fly that kind of airframe.
Nov 07, 2014, 01:54 AM
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Im still going to say 120's. The horten was bigger, but it was also heavier. That airplane was a 4 minute and you better be on final approach to land. If you werent, 10 seconds later you were a 36lb glider with the glide ratio of a brick.
The 90's flew the thing, but the performance was sorely lacking, the most i could ever so was a sloppy wing over as it just didnt have the air volume to take it over a loop.

The Slightly reduced efflux of the 120's isnt going to be that big of a deal on the F14. That fuselage makes between 30-40% of the lift of the entire airframs. With the 120's you'll have the air volume to get off of grass.
While i dont doubt 90's with fly this, i dont doubt that the performance will be less than ideal either.


Plus look at it this way../. If you run 90's on 12s and the performance sucks or it doesnt get off the ground, you have no where else to go for more power Except a larger fan.
With 120's, if you run 8 or 10s, you have the option of increasing the power.


I have been trying to talk JHH into getting their 1/10 F14 into kittable stage, i think a semi composite version of that model would sell well.
Nov 07, 2014, 07:02 AM
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edf_rookie's Avatar
Quote:
Originally Posted by invertmast

I have been trying to talk JHH into getting their 1/10 F14 into kittable stage, i think a semi composite version of that model would sell well.
Keep taking to them That would definitely have me interested if they were to sell the 1/10 F14 in a kit. The skymaster one is really nice but just too much - something that could take a pair of 120mm edf's or a pair of P60's would be perfect.
Nov 07, 2014, 09:08 AM
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Quote:
Originally Posted by edf_rookie
Keep taking to them That would definitely have me interested if they were to sell the 1/10 F14 in a kit. The skymaster one is really nice but just too much - something that could take a pair of 120mm edf's or a pair of P60's would be perfect.
Yea, the problem isnt getting it to that stags, the problem is people who say "id buy one!" And never do. My experience's are, for every 10 people that say "id buy it", MAYBE one will actually follow through.


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