Nathan King

I am in the process of restoring an old MK Joker and have two questions:

1. Should I use retracts / how much will not having them negatively affect the flight performance? I am worried about weight (extra servo + linkages) since I've had to make some repairs. I have painstakingly kept all repairs as light and strong as possible, but as you know It's almost impossible to not have any weight gain.

2. The wooden engine mount has mounting holes 25mm (1" ) Center-to-Center Front-to-Rear and 2mm (2.05" ) Center-to-Center Side-to-Side. Any ideas on what engine was originally mounted (Webra .60?)? I will have to find an engine with equivalent mount dimensions since the mount is wood and permanently part of the nose structure.

She's really starting to look pretty again and I want to do her justice.

Thanks!

Deadstik

My Feedback: (8)

Nathan,

I'd definitely keep the retracts and the plane will just fly better and look better when the gear goes up. With the power available from today's engines, the small weight added will be much less than if you try to retrofit fixed gear. As far as what engine.. I suggest you look in a Tower catalog. Usually, they have all the mounting dimensions. That will probably give you an idea of where to start. Even though the plane does have a beam mounting system, you can always fill the holes with epoxy/cabosil and redrill to whatever engine you choose. Today, the manufacturers are putting bigger displacements in smaller packages.. so just see what will fit. Post a picture of your rebuild.. I'm sure others would like to see it. Good luck with your project, fly something unique instead of one just like everyone else has...

Dan
Carolina Custom Aircraft

Atlanta 60

My Feedback: (18)

Ooooh Ooooh...Photos please!!

I vote Retracts also!!

I don't have a beam mount Airframe yet...But I do have soft mounts on hand for the day that I build one...That is something you may consider...I'm a soft mount believer...Here is an example of Dave Brown's Soft Beam Mount:
http://www.dbproducts.com/store/vd4c.htm

I'm not sure how others feel about "Soft Mounts"..I haven't really seen that discussion abound here yet...But I personally soft mount/isolate all my engines on everything I build...

Good Luck with your re-build!! Please keep us posted!!

Have Fun...

Chuck

airbusdrvr

Question about Dave Brown's mount removed. Found the answer. Sorry.

s. wallace

My Feedback: (24)

Great flying model & worthy of a quality restoration! Your Joker likely used the MK beam type soft mount, you mat be able to find them in 60 size from Central Hobbies. They work fine on 60 size 2 strokes, personally I didn't have luck with MK mounts on 4 cycles.

What are you planning for power? Mine used an OS 61RF-P & it was plenty of go...YS 60-61 would be good too. I saw a few back in the day with Enya & OS 1.20 4 cycles- too heavy for their power (this was pre-YS times). Keep it 2 stroke, simple & light...and oh yeah..gotta have retracts!

Atlanta 60

My Feedback: (18)

I just measured my OS 61RF-P...It has the same hole pattern as you listed 1" x 2.05"...

Have Fun...

Chuck

Nathan King

I purchased this airframe at an auction for $55 I bought it as a fixer-upper, but when I peeled away the ancient covering I was in for a few surprises. Total cost for repairs so far: $0 (spare balsa and lots of free time). I seem to have secured a good deal since the kits go for $400.

The 61 RF-P seems like a good choice, It's just a matter of finding one.

Due to popular demand I have reluctantly uploaded pictures. It doesn't seem like much now, but I assure you it was far worse. The list of completed items is as follows:

1. Fuel damage to the nose area
2. Left horizontal stabilizer section completely severed
3. Right wing section almost completely severed toward the outside and damage almost halfway in next to the fuselage.
4.Three ribs needed to be completely remade.

I had to build a jig to make sure I did not build a warp into the stab or wing. On the pictures the right wing section appears to have a big white gouge, but that is just some discoloration. As you can see, the wing is fiberglassed in the center.

Instead of reinforcing the broken material, I have made sure to cut the old out and replace with new to keep the weight close to original.

I still have to remove a bit more leftover gummy covering and do final surface preparation for covering.

flywilly

My Feedback: (121)

Hey Nathan,
I've built 5 Jokers. 4 with retracts and the last (which was an ebay 'salvage' of a partially built kit) with fixed gear. Fixed gear or retracts make no difference in flight performance. Since you're rebuilding and it seems the Joker already had retracts I would keep them. I preferred mechanical retracts in tail draggers (MK gear). My Jokers have had progressively more power. The first had an OS .61RF ABC, but no pump until I retrofitted a Perry pump. The middle 3 had OS .61RF ABC-P engines and the last had a Hanno Special in it (with fixed gear and all monokote it weighed about 7.25 lbs and had great vertical performance). I'd like to build another one with fixed gear and a YS 110 4-stroke in it. Matt flew the Saphir (.60 sized) at the '89 WC with a YS 1.20 in it - very impressive performance.
Good luck and enjoy!!
Will B.

Atlanta 60

My Feedback: (18)

Excellant Nathan...Keep up the good work...And Keep us posted on how it goes!!

I look forward to seeing you get this Baby in the Air!!

Have Fun...

Chuck

Nathan King

flywilly,

I'm very pleased with the weight you quoted of 7.25 lbs. If everything goes according to plan mine will come out right in that ballpark. WOW, a YS 1.20? That must have been insane! I'm not going to go that crazy with power, I'll keep it how it was in the golden age of pattern.

I have decided to go with retracts. You just can't beat having that sleek beauty zooming past the flight line with nothing sticking out. Can't wait to see this thing leave the bounds of gravity!

propbuster

My Feedback: (1)

Nathan, keep up the good work, it's looking nice already!

Nathan King

Well, it will be ready to cover in about a week. [8D]

Thanks for the support, it's really keeping me motivated since this has been such a looooooong project. I'll keep you updated.

Nathan King

I just noticed something strange. This is probably a dumb question, but I don't have any experience with older engines. Were they smaller for the same displacement/carburetor lower? I am asking because it looks like if I keep the tank where it is the centerline of the fuel tank will be well above the carburetor with the engine inverted. Tank placement seems very high.

mmattockx

The 60's of this era all ran pumps, making the tank position irrelevant.


Mark

Nathan King

flywilly mentioned he didn't use a pump at first. I was wondering how that worked. I'm planning on using a pump though since not having one will just be more trouble.

But yes, that question looked stupid... [sm=red_smile.gif]

Nathan King

Looking better every day.......

Everyone I regularly talk to knows something is up because I can't wipe the huge smile off my face!

Atlanta 60

My Feedback: (18)

That Jokers Wild!!


Sorry...Bad I know....

Have Fun...

Chuck

Nathan King

Covering is coming a bit ahead of schedule. I wasn't planning on starting until next week, but I have had more time to work than I thought. It still looks a little plain because I don't have the lettering done yet. The repairs are invisible and the surface is glass smooth.

The wing will have "Joker" written on the left side of the wing along with my AMA # on the right. The underside will have black and red diamonds, hearts, spades, and clubs for orientation. All control surfaces will be red. The fuselage will have a white base with red on the top front up to the cockpit along with black stripes. The vertical stabilizer will have the original "MK" stickers that I was able to salvage off the old covering. I'm still on the hunt for a Max-61 RF ABC-P.

Nathan King

It's a beautiful weekend to burn off brain cells with resin. The fuselage is going well, although my arms may fall off from the sanding! [:@] It will be worth it. While a layer sets I put a black stripe and the "JOKER" text on the wing:



It was pretty embarrassing to go and buy clear nail polish! [sm=lol.gif] You are all probably thinking "BORING" but there will be some color, just be patient.

Razor-RCU

My Feedback: (50)

AWESOME!!

Atlanta 60

My Feedback: (18)

I Agree!!

Have Fun...

Chuck

Nathan King

I have two coats on and one to go. I had to sand off years of who knows what under the covering. The finish is pretty smooth, but it could use one more to cover the rest of the grain. After that it will be primer and paint. I work down to about 400 grit sandpaper and the result is glass. The picture is before sanding.

I guess I should explain why the cockpit was done before the finish. My first model was a Carl Goldberg Electra kit, and I did a ton of work detailing the cockpit. Due to my ignorance I used CA glue to put the canopy down. [:@] Instead of dealing with the fog I just painted the canopy a solid color. I now make an interior before painting the canopy for good luck! [sm=spinnyeyes.gif] It was futile to make it look nice anyway because after I covered it resembled a large prune! Plus I crashed it about a dozen times because I taught myself how to fly. Oh well, I got really good at repair very quickly. Enough of my rambling, bring on the picture!

s. wallace

My Feedback: (24)

Now that I get a clear look at the fuselage I see a mistake by the original builder-I'm sure you already realize this but the original builder butchered the wing fillets! He just glued on the pre-cut MK parts and made no attempt to carve them. You can carefully carve & sand them to the proper contour, and use expoxolite or similar if need be to help make the fillets flow smoothly to the wing joint.

There was a real art (and a good bit of work) with a balsa fuse pattern model to doing beautiful fillets, but they are well worth it with your restoration of this great older model. I'm sure if you check the build thread on the "Blue Angel" you'll see photos illustrating what I'm trying to say.

Nathan King

Yes, I recently noticed that. They never seemed quite right to me and after I saw a few pictures I knew it was wrong! There have been a few other things like this that I have fixed up already. The vertical stabilizer had a few issues, and where the vertical stab meets the fuselage is slightly butchered. I'm actually a bit afraid to touch them in fear of ruining it.

I would just build a brand new kit, but as a college student I don't have that kind of money!

Ahh yes, the Blue Angel build by 8178. I also enjoyed his Kwik Fly III build/restoration. That guy has WAY too much skill for one man and really drives me nuts. I feel like trashing all my models after I look at one of his threads. [:'(] I wonder if he'd let me be his apprentice.
He is truly an artist.

Nathan King

I have hit a snag. Some of the old balsa sheeting, especially on the rudder is quite brittle. I am probably going to have to resheet some of it. [sm=angry_smile.gif]