Warbirdguy

I got one built, flown, but had a bad landing that damaged the nose. Been repaired but needs paint. I have pictures of it if you like. Id make you a great deal on it I was thinking of converting it to turbine myself, but have too many other projects to complete.

A little history on Cressline models. They sold out to some guys using Flight Tech name. They contacted me to do some epoxy glass fuse and parts and update the molds to the F5 and F20 to pull a one piece fuse. I did so and made a few parts for them and never could seem to satisfy them lol. So sent their stuff back and they soon went belly up. I brokered a deal with them with some guys out of Chattanooga and they ended up selling to Jetmart in Ga where the molds are today.

The F20 I have was a demo jet built by jetmart.

They are great flying jet with a fairly thick airfoil that gives plenty of lift.

Good luck with the build, Ill be watching it progress.

WBG

ron Sweeney

Referring to the pictures of your engine set up the silicone OS 'D' ring fitted to the exhaust has a very short life span, The tuned pipe appears to be a very noisy version, and can I see a torque rod linkage to the aileron? No criticism intended merely some observations. Nearly all Byrofan installations employed an inverted engine there is just a slightly increased risk of engine flooding. I think I might start on mine next you have started an itch.

Ram-bro

My Feedback: (101)

with all this talk about D/Fs...maybe one of the big jet events can set aside for an hr or 2 a D/Fs only( non-electric) time slot and bring back some of the old events.........just a thought

Hinckley Bill

My Feedback: (569)

The first "jet" I purchased was a F-20 produced by World Engineering - aka Ralph Saldivar (the design would later be sold to Knights of the Air)......it was delivered in a huge box by a freight company. They rang the doorbell to my apartment and my wife was stunned to see it come through the door, almost touching the 8 1/2' ceiling! It's 94 inches long and the fuse was ONE PIECE!

I never got the chance to build it but it sits waiting in my basement.......perhaps an EDF conversion?

reaaz

Mr Sweeney.. hi

I got the new engine, new fan & Noisy pipe in a deal.. so its good to have the extra unit waiting for.... the second jet lol! Or maybe an twin ducted fan avonds F15
Otherwise I have another unit with JMP system 2 pipe & coupling that should be longer lasting & will be the main setup. How long do the system 2 couplings hold up?

ron Sweeney

Hi Reaaz, The JMP coupler is by far the longest lasting in my opinion and the pipe is comparatively quiet. I don't know whether the couplers are still available. This system also seems to provide a better cushion since the pipes are vulnerable to fracture at the neck if they are mounted rather than hung from the duct. The exhaust adapter has a habit of coming loose and chattering the two mounting screws. The fix is to de-grease the engine and exhaust adapter faces and bond them and the two mounting screws tightly with epoxy. My most recent D/F models were a Mig 29 twin,sold a Sukhoi 27 twin converted to turbine, and a 30 year old JMP Phantom twin also converted to turbine, and they all flew off a grass strip. I am currently building a BVM Maverick and was going to go the d/f route but changed my mind a couple of months ago and converted it to turbine.
Oh by the way de-grease and loctite all the engine screws, especially the throttle barrel retaining screw Ron.

tlj125

My Feedback: (1)

My experience is very similar to Ron's. I would get about 30-75 flights on an engine/pipe set-up before it would destroy itself. I used the OS 91, Ramtech fan, JMP quite pipe. The problem with short life was mostly leaning out the engine too much. Hard to find just the right spot. Just a little rich and the plane would fly much slower. Too lean and the engine would lock-up. Usually the rod broke. A few times the pipe would fall out of the plane while in the air. Looked like a bomb drop. Vibration was tough on the pipes and couplers. And of course all the fasteners on the engine and fan. Even with red loctite. Nothing I ever tried would last for long. I enjoyed it though. It was the best thing going at the time. Anyone who showed up at the field with a ducted fan was the center of attention. Everyone wanted to see them fly.

Terry

reaaz

Hey Warbird guy, Would you share some of the pics of your F20.. It looks good in that pic.
Do you have pics of the underside.. landing gear etc?

Here are most of the components in Kit & template sheet with wing plan, You can see the Looong torque rod for aileron Control, Black rolled fiberglass sheet for duct, Intake duct, stock material, hardware pack, foam cut stabilizer with blocks for embedding shaft for control..etc..

Note the postion of the wheel well, Its too far foward & also wheel well should be in the fuse itself.. I intend to locate it behind the spar... It will probably make takeoff a heck of a chore though

Terry, Never mind that they are a bit cranky, getting one of these Nitro fans Jobs going is still just too tempting to leave alone! lol

reaaz

Got the e6000 Glue from Micheals... Setting some Polyester fuse to Ply test peices to see how it peforms before I start gluing the engine bearer blocks together.
I am still concerned about the glue to be used in this fuse, seems the debate is a hot topic

http://www.rcuniverse.com/forum/m_10...m.htm#11092100

Warbirdguy

Ill get it down in the next couple days and get some better pics of it top and bottom.

I got a bvm fan with the bvm .82 and pipe and a complete thrust tube assy from a BVM Maverick that I was going to use in it. Im moving away from jets so all is up on the table to leave here lol.

WBG

reaaz

Looking foward to seeing more pics of your F20 Warbirdguy.... What are you looking to sell by the way???

In the meantime I have decided on a Epoxy for main load bearing structures.. Its the System Three T-88... good for Polyester composite bonds as Spec sheet states a lap sheer load of 2800Lbs in a Polyester bond.. Its also a rather thick Epoxy (really good for gap fillling) & starts setting up in an Hour.. full cure in 24hrs or so

1. First up was gluing in the spars to Fuse at the same time I added in custom curved Ribs (instead of bulkhead as shown in the plans) This rib will transfer load from spar to fuse shell
& has a much higher contact area than The bulkhead & is lighter!

2. Once that set.. I added 1/2 X 3/8 gear rail to spar to strengthen spar at the fan cutout area

3. With spar secured, I made the engine Bear plate assemblies

4. Now, it simply a matter of snugging down the Dynamax Fan unit Lip over the Intake ducting lip
then Clamping the Enginer bearers to the Dynamax bolting tab & test fitting/sanding the Bearer plate faces till they conform to fuse shell

5. Glued in the bearer plate to fuse with the T-88 with Fan unit snugged down & with the Bearer plates clamped to The Dynamax tab
So once it had set up, I now have a Fan unit that will slide right into place in perfect alignment with Ducting lip

Note that engine is being mounted upside down & that there will be no upper hatch!

A10FLYR

My Feedback: (1)

I believe you should re-engineer the motor mounts. A 1/2 or 3/4 ccircle former should be part of the motor mount! Anyone else agree?

grbaker

My Feedback: (29)

+1

All of the DFs I built had the fan mount glued to the fuse side and at least one fuse former. Since you don't have a former to glue to, I would fabricate at least a half former under your existing fan mounts and tie the mounts together.

reaaz

Interesting in that I was thinking if such former's were necessary to keep the Fuse side from buckling/vibrating with power on. I can easily add a half former under the rear bearing plate
to help stiffen the fuse sidewall. At least the front of the former ties in to the curved vertical rib.

Or is the issue, the strength of the bearing plate itself?

In the meantime, going to Start to figure out/finish the Intake scoops

Warbirdguy

Guys, sorry for not posting pics of mine. Im kinda under the weather.

In reguards to the fan mount. I had designed and built a fan mount simular to the BVM design. I made two formers , front and rear, to carry a mounting beam between them that was removable. The fan then mounted onto that beam with some vibration bushings. When I get to feeling better, Ill get the F20 out and get some shots and some pictures of the fan mounting system I designed to fit this F20.

Your build looks great so far

WBG

Warbirdguy

Here you go reaaz.

There is also a servo installed on the rudder. Looks like a futaba, small, probably high tourque. It looks new from what I can see but I cant see the top of the servo to get numbers.

I checked the weight on it also. 8.5 lbs.

Im not going to finish it. I was going to strip it down and do a military color, but just dont have time.

I bought a set of spring air retracts for it, and I have a KBV 82 in BVM fan and BVM puffer pipe. Also a BVM tailpipe from a Maverick that I would let it all go in a package deal. I dont want to sell the retracts unless they go with the jet. I have another project they will fit.

Also, included in the pictures, is that engine cradle I built to fit the F20. That has to be installed in a new build as its being built. As you can see, it takes all the stress off the fuse sides and put it directly to the formers.

Anyways, enjoy the pictures.

WBG

reaaz

Great Pictures... Your Plane is still in great shape, Just lay a little bit of glasscloth inside the nose, Sand & refinish nose area & its done! Might be tempted to take it later off your hands
if no other wants it later. but quite a nice finished jet for anyone wanting a rare Cressline F20

Like your anti vibe Setup... Wondering how I can incorperate such into mine...Will think about it. Also I see you have the gear in correct position, behind the spar on the wing.
How did it takeoff? Would you recommend putting my landing gear behind the spar

So today I've begun the intakes.. traced out, cut & glued the airsplitter from 1/16 ply in the kit, waiting for it to dry & will continue the inlet construction tommorow

Warbirdguy

I dont know how it flew. It did fly however, cause it was Jet Marts demo jet. The patch is already made inside the fuse. Just finish work to complete.

I layed several fusalages up for Flight tech, the people who obtained the molds from Cressline. I had all the plans and when I made the anti vibration setup, it was to fit the provided former locations. So you can either attach to a completed model and cut the side mounts away from the fuse side, or build it in during building. They are also built to demsnions of using saddle tanks. The caps on the tanks fit into the two holes in the front former and the main body of the tanks set between the fan and fuse.

The landing gear location was done by Jet Mart, so I dont know how they work out.

It has flaps but not sure if I would use them with a full flying stab. Ive been told they disturb the air flowing over the stabs and can cause a stall on landing. That may be what happened to this one. I was told it took damage on landing.

If I dont sell it, Ill just hang it back up and one day, when Im bored and nothing to do, I may stick this engine, fan, pipe, thrust tube in, radio, retracts and go give it a whirl

I would almost sell someone the fan, engine, pipe, thrust tube and retracts and give them the jet. Shipping this thing is where things get pricey lol. I would love to see it fly again myself. Even if it werent by me.

Anyways, good luck with your build.

I can tell you this, on the ones I layed up for Flight tech, they had carbon fiber reinforcements where the fan mounts attached to the inside of the fuse. That was one place they said they had issues with fuse cracking. That was also the reason why I engineered the alternate fan mount system. But, they went belly up before that could be incoorporated. I also made a mold from the cocpit area where I had intended to make a canopy frame. Its roughly made and needs edges trimed to size and frame lines etched in. Just relects collected for future use... just like me lol.

WBG

Skybouncer

My Feedback: (3)

Hi Guys, I will see if I can fill in a few of the blanks for you. The F-20 was underpowered with a Ramtec fan and K&B .82 in it.
It flew OK just needed more power scotty! It fell victim to what happened to hundrends of DFs back in the day.
Engine quits at the wrong time and place and you have to make a off feild landing, It was a good landing but it was really rough
terrain and a big ditch had something to do with it.
Had plans too but I never got around to putting a turbine in it.
I want to do another one someday and convert it to EDF, I have converted my BD5 to EDF and Its awesome with the power that im
getting now over the IC engines and my bet would be that the F-20 would be too.
Im going EDF all the way so I got a F-14 building right now.
The nitro stuff was very cool back in the day but im moving on to EDF, Got a bunch of IC DF stuff that I need to get rid of as soon as I get the time to round it all up and put it in a box for a one lot price.
Ronnie

Bob_B

My Feedback: (11)

Ronnie would love to see you produce the f20 &bd5 again.

Warbirdguy

Hey Ronnie! Good to see your still around

I talked to Steve back in the summer and Docyates. We all were asking about you. You going to Perry this year?

I agree with the assesment of the engine choice for the F20. I figured the BVM setup I had would be a notch up from the ramtec. But, I really wanted to slilp a tubine in this thing I just dont have the time.

You still have any molds for sale? PM me if you do.

Have a great Turkey day. Hope to chat with you soon.

WBG ....Jamie

Skybouncer

My Feedback: (3)

Hi Bob, I still produce a very limited # of kits as I have the time, I think I got a BD5 on the shelf but I havent done anything with the F-20 for some time.

Hey Jamie, I never left! LOL, been doing this stuff for 40 years, cant get rid of it man, got epoxy in my bloodstream i guess, LOL
Im in the shop almost everday working on or building something, Just finished a 3 month contracted mold project and got a couple of molds left to do for it in the future. Once it done them Im going to finished the EDF F-14 and then jump on the A-6 hard and finish it up, its been a long long project but I want it finished now.
I may be at Perry this year, its hard to sell any jet stuff there, you got to give it away, but if I got some stuff to give away ill be there LOL, I mainly go there to buy bulk supplies.
See ya

Warbirdguy

Great to hear from you Ronnie.

I know what you mean bout working every day. I need to be but this darn sinus stuff is bout to kill me and the wife. I sold my C47 molds and ready to move on to something else. Thinking of some 120 sized warbirds. Been thinking of a 100" panther jet. Just not sure I want to get back into anything large. Have a friend up here that can build a plug, but just alot of work and Im old :P Maybe even as old as you lol.

Your right about Perry. I thought about just taking the wife down this time, walk around for a day and see if there are any deals, then head out the next morning for the coast or NC.

Anyways, take care and hope you had a great Turkey day.

Jamie

Ram-bro

My Feedback: (101)

warbirdguy, whatever happened to this build?

reaaz

Hey Ram-bo, Sorry I put the jets in storage a while ago as someone moved into my rc room (taken over)
good news since then is I moved house 2 months ago with lotss more room & everything is back home & have been eyeing that F20 to finish it up. Got a second unused dynamax unit & a second Os 91.. hopefullI can start at some point this year. will continue on this thread once