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Outdoor Free Flight Forum => Free Flight Scale => Topic started by: Crabby on March 19, 2016, 03:31:46 PM



Title: Dick Howard Piper Navajo Chieftain
Post by: Crabby on March 19, 2016, 03:31:46 PM
I have an urge to do a multi and this thing has been bugging me for a long time...so I put the Spirit of St. Louis on hold since I don't relish the idea of building that engine especially. This thing is more or less two peanuts on a 24 in wing...at least that's the way I am approaching it...anybody feel free to chime in as I go... sorry I refer to my planes as "things". That's what they are. I am just laying the sticks in, I used my patented longeron roller method here to get that curve without incurring any stress. I also split my mag tape to hold all that in place. This is a great way to do fuse sides and make 'em identical...mean time saving my back because I work standing up. I like my magnet board a hell of a lot.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: strat-o on March 20, 2016, 12:37:11 AM
I'm interested in seeing your progress on this.  The engine nacelles are surprisingly long so no problems with short motor runs.  I don't recall seeing this wing design before, a cracked rib with an added balsa curve to the leading edge upper surface.  Kinda cool.

Marlin


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on March 20, 2016, 10:43:05 AM
Hi Marlin, thanks for stopping in...I am a cracked rib fan, I don't even have a good reason other than liking the way it looks...but there are some good reasons for it...


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Tim Horne on March 20, 2016, 01:18:29 PM
Hi Crabby, this one has been on my "to do" list for quite a while too. Looking forward to seeing how yours turns out and flies.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on March 20, 2016, 01:30:43 PM
OK Tim stick around and we'll see how the toast burns!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: FLYACE1946 on March 21, 2016, 12:38:49 PM
I will gladly watch also. Hope you are very happy with the results. Good design and an accomplished model designer. Thanks for sharing.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: strat-o on March 21, 2016, 11:26:11 PM
Hi Crabby, is there a write up on here somewhere describing your building board?  Intrigued by your magnetic spliney-looking things.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: flydean1 on March 24, 2016, 07:28:35 PM
Flew & taught "real" Navajos for 6 years at Flight Safety-Lakeland.  I regard it as sort of an old friend.  Ferried one to Riverside, CA, & had the gear collapse on one at Key West, FL.  Great plane.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on March 24, 2016, 09:07:11 PM
Hi Strato, Fly Dean & Fly Ace thanks guys for dropping in! Fly Ace this thing has been haunting me for years and now that I seem to have gotten over the "builders wall" I am going for the builds that I want to do...I don't have the time to do the stuff I don't want to do. I have long been a Dick Howard fan, and Strato, my building board was discussed ad-nauseum in my Dave Mitchell Hell Diver build, but as I go through this build, currently stalled due to life obligations, I will include the benefits and virtues as I go...Fly Dean, I saw a few of these things last week at the Tico Air Show, sitting there being pretty...I got really pumped to do the Howard model, and plan to use my Old buddy the Duco Guru's spinner prop concoction to the best of my ability... hang in fellas I am going to set up a fuse jig and get back on the horse as they say!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on March 26, 2016, 04:29:39 PM
OK meanwhile back at the bench....I am aware of an issue, check the cross-section from stations #4-8 if you don't have the plan you can download it here in the builders plan gallery. The sides are flat up to the windows then they bevel in a few degrees. I built the sides flat but there is a joint at that point so I made a jig inside a jig. I used 90 degree aluminum angle with a magnet shim down at the base. Now I can crack the joint before I put the cross-members in. Of course before I start glueing stuff together I have to roll the fuse sides to get a nice curve without incurring a stressed-out banana situation. Most guys reading this are bored because they are already black-belt ninja balsa butchers... if this is you please chime in!
If not, here is how I do things till instructed otherwise... Oh and Strato, one of the things I love about a magnetic building board....no &^%$#ing pins!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Glenn (gravitywell) Reach on March 26, 2016, 06:39:24 PM
Hi Crabby.  Watching this build with a lot of interest.  Question....how are the angle iron pieces held to the table?


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on March 26, 2016, 07:58:08 PM
Glenn its a vertical building board not a table...those angle aluminum members are held on with adhesive backed magnetic tape. I build standing up mostly to save on Advil  ::) ::)


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Glenn (gravitywell) Reach on March 26, 2016, 08:09:31 PM
I knew that it was a vertical board, that's why I thought it odd that they didn't fall off! LOL  Magnets on the bottom make sense.....Thanks Crabby. ;D


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Broken Strands on March 27, 2016, 02:46:29 AM
R, it's been a while, hope all is well!  I'll be following with interest too.

Got some info you might find useful.  For a few years we had a Grand Canyon tour operator based here at VGT.  Their fleet consisted mostly of standard, piston-powered Chieftains but they also had one turboprop version of the same plane.  I'd always thought the turbine engine version had longer engine nacelles but wasn't sure, the difference isn't obvious.  One day curiosity got the better of me so I got out the measuring tape.  The engine nacelles on the piston version are (surprisingly)two inches longer!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on March 27, 2016, 09:32:46 AM
Hello Broken Strands thanks for the pointer, I will think about that when I go to build the nacelles I was thinking about cheating anyway, but now I won't have to! Glenn I know you knew about my vert board I just wanted to take the opportunity to point that fact out to others. So many guys cut their building time because of neck strain. Of coarse you can make a board like mine without it being magnetic. I just hate pins after so many ass chewings by my Olde Man about pin holes in the work, plus mag tape assures me everything's gonna be straight and true, and I won't be paying Peter with Paul's dividends further down the pike!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: FLYACE1946 on March 27, 2016, 06:12:24 PM
What is the length  of the fuselage when the article in the magazine shows the wingspan to be 27 inches. Just curious.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on March 28, 2016, 09:28:46 AM
its 21.75, but my plan was scanned and reprinted from the magazine, and things are a little whack and I am having to correct as I go, or there may have been a mistake or two in the original dwg...not as likely...I would like to see that article as I don't have the mag anymore could you possibly post it or PM me? It would be much appreciated...Now some more pics...because of the way I did the sides I had to jig the thing upside down...I have a nice balsa stripper and after cutting a sheet of 1/16 the right width, I just stripped all those cross members...getting the glue to 'em was a pain but I did it without breaking anything...yet


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: FLYACE1946 on August 01, 2016, 01:40:40 PM
When I get to the point of joining the sides for the fuselage I will use a jig designed and built by Al Cleave. Stay tuned for photos but don't hold your breath. I think my Dick Howard designed F7F Tigercat will be first one up as it was recommended as a very good project.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on August 25, 2016, 09:25:51 AM
I am gonna roll the sides lightly to induce a slight curve before I join the sides at the tail posts.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Tyrannt on August 25, 2016, 02:35:19 PM
Hi Crabby. Great build. What are you going to roll the fuselage with.  I have seen you use this method with great results.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Sky9pilot on August 25, 2016, 03:52:28 PM
Plan can be found here:  Piper Navaho Chieftain  (http://www.hippocketaeronautics.com/hpa_plans/categories.php?cat_id=20&page=19) Just for those who might be looking for it.
This is a great looking build. I'm enjoying following it. 
Sky9pilot


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on August 25, 2016, 04:19:08 PM
Hi Tyrant, you can roll with any cylinder, I use a fat Xacto handle...but I regret to say care must be utilized to be sure one doesn't flatten the framework as I do from time to time. Go easy and select good hard stick!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on August 26, 2016, 09:23:49 AM
Tyrant you can't roll with ANY cylinder...use something like a .75-1.0 wooden dowel...For those who might attempt this build....resign to the fact that its a tedious toothpick trial. I lost interest and motivation somewhere during the fuse...
then I found out that I had neglected to double check the "footprint" for symmetry.... (as you will see this plan was stitched together about station #11.) no excuses.. I built a &^k%$#ing banana fuse! So, I had to resist the two hand crumble. I have matured some. I ripped off the framing past station #8, quit and came back the next day. Please redraw that footprint if you are gonna try this thing, and by all means strip your 1/16 from the same sheet. It all needs to be the same density. I carelessly chose 1/16 stick from my half-assed collection, and now it all different widths and densities, so now I am "paying Peter" for the rest of the build and will now probably have to fix-fudge the wing saddle! I thought as a builder I was waaay past this sophmore s$%%#@t! Ego be damned! nose to the grindstone! No whining! and a lesson learned for the umpteenth time! Monkeys learn faster! I'm Crabby


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on August 26, 2016, 10:16:34 AM
OK back to zero-zero... somewhat straight and square, but reminded to always maintain awareness and to apply the utmost respect for balsawood!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Modelace on August 26, 2016, 12:30:43 PM
Tyrant you can't roll with ANY cylinder...use something like a .75-1.0 wooden dowel...For those who might attempt this build....resign to the fact that its a tedious toothpick trial. I lost interest and motivation somewhere during the fuse...
then I found out that I had neglected to double check the "footprint" for symmetry.... (as you will see this plan was stitched together about station #11.) no excuses.. I built a &^k%$#ing banana fuse! So, I had to resist the two hand crumble. I have matured some. I ripped off the framing past station #8, quit and came back the next day. Please redraw that footprint if you are gonna try this thing, and by all means strip your 1/16 from the same sheet. It all needs to be the same density. I carelessly chose 1/16 stick from my half-assed collection, and now it all different widths and densities, so now I am "paying Peter" for the rest of the build and will now probably have to fix-fudge the wing saddle! I thought as a builder I was waaay past this sophmore s$%%#@t! Ego be damned! nose to the grindstone! No whining! and a lesson learned for the umpteenth time! Monkeys learn faster! I'm Crabby


Tsk, Tsk. Such anger for a (more or less) common mistake. :o If you don't have one, buy a caliper (Cheap at Harbor Freight) and measure those sticks before you glue. Also, hang them off the edge of a table (with only 1/2" of the sticks held to the table edge). USE THE ONES THAT SAG THE SAME!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on August 26, 2016, 02:54:30 PM
Sorry Guru, :-[ I guess I just don't get out too often. I have several calipers. I suffer from the curse of availability. Anyway, the beat goes on next up is to build the wing, but I am gonna mirror-image the left side and straighten things up a bit first.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: strat-o on August 26, 2016, 04:10:11 PM
Worry?  Nope, that's just the fuselage.  And no rubber in it so it's just for show anyway.  Just cover it and paint it like the Arizona state flag or something dazzley like that.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on August 28, 2016, 08:12:09 AM
Well, here is the final sad violin song on my Dick Howard stick box! But on the cheery side, its all straight, and I am feeling better thanks to Drs Guru and Strato for talking me off the ledge! now for the other two fuselages. Guru, gonna imitate your spinner routine and do Midkiff baked basswood popsickle sticks. I can eyeball the three blade drill locations as well as the next guy. But hold not thy breath, I'm going in for a heart operation tomorrow! If I make it back I will get on with this build tomorrow pm!



Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Modelace on August 28, 2016, 11:11:33 AM
To save some "eyeball" cut a piece of masking tape about 1/16" wide. Wrap it around your spinner at the correct diameter where the props are to be mounted.
Now cut the tape to the EXACT length (full circumference) while it is still on the spinner and peel it off. Divide the peeled tape into 3 equal parts and mark it with a pencil. Put it back in place and mark three EQUAL spots, exactly 120 degrees apart. Drill!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: FLYACE1946 on August 29, 2016, 09:47:36 AM
Crabby I hope to see you back on the project soon. Hope all is well with you after the heart operation.

Allen


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Ki44LvR on August 30, 2016, 08:40:53 AM
Crabby, looking very nice - great to see the fuselage coming together and looking forward to seeing the rest of the construction. I do hope that things went well with your op and that we'll see you back here soon.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: faif2d on August 30, 2016, 11:46:42 AM
Hope the surgery goes well and look forward to seeing the build!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: rgroener on August 31, 2016, 06:22:01 AM
Crabby, you are not alone, I did the same mistake on a plan which was stitched together....
The difference is, that I did not have your self control. I smashed it and built a new one. Your approach is much better :)
Popcorn is ready, I will follow you.

Roman


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on August 31, 2016, 08:38:24 AM
Fellows many thanks for the well-wishes! Yesterday I rec'd medicated stent #5 this one in the Obtuse marginal artery. Its was 80% blocked and took full air pressure angioplast to pop it open before the stent was inserted. I was able to watch the whole thing. I will not preach much here, but will say, that odd sensation in your chest and arms that you will shrug off is a major red flag to get your fat ass to the ER, while you have symptoms to diagnose! Most likely when the widow-maker comes, you will quietly slump over your building board, and your sad widow will have to take it from there! Eat right don't smoke, have at least a modicum of awareness of what goes down your pie-hole, and you will still have troubles, but your awareness will be keener. If you are a stress addict, find peace, grab it and never let go its your best bet! END OF SERMON.

OK I was going to build the wing next but since the nacelles are mounted to the top, and a major part of the wing construction, I opted to do them next... as has been said, they are actually 2 more fuselages. I am going to build them all at once and have set up jigs on my mag-board, carefully made 4 identical NS-1. I made my patterns from 10 mil polycarb. You can get as much as you need out of the dumpster behind your local sign shop. I have an unreliable notching tool that I use, see pic. I need to make a better one,... it used to be able to notch a stack of ribs straight and square. This thing is a mess. You will note NS-1 has a deep notch on its bottom...be sure that deep notch is on the money, for it slides onto the main wing spar, If those notches are sketch you will be playing the devil's fiddle to the dreary end. That notch keys on N-4. As an afterthought, I chose the hardest 1/16 sheet I had in the house and stripped my sticks and made NS-1's from it. These nacelles are the power-houses of this model and I won't be weighing them! They will be two light-weight brick $#it-houses!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on August 31, 2016, 11:40:51 AM
My building sessions are getting to be more about using a mag board as they are building a certain subject...After stripping some stick from the same hard sheet, I rolled them several times to induce a curve...being careful not to flatten too much them in the process. I then split some magnet and followed the top curve of the nacelle, lay in the strip and snugged the whole thing in tight...I double glue everything with Duco...I am looking around for a tube of 527. Duco is getting scarce in the stores...I know I can get it on-line but that is no fun for me.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Art356A on August 31, 2016, 02:37:38 PM
Ace Hardware has Duco

a.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: FLYACE1946 on August 31, 2016, 05:59:22 PM
527 is found at Michaels store.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: faif2d on August 31, 2016, 08:45:10 PM
527 is also in the Wal Mart crafts section.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on September 01, 2016, 04:12:18 AM
OK, I get it. "Go to all the obvious places" too bad I already thought of those. ::) There is a hole in the wall hobby shop here in Melbourne called Ernie's. Its a waaay back place with stuff only a human relic could relate to. But his prices in there are certainly up to date! I might bite the big one and pay him, now that I am beyond-principles with him. At least he's close to the Heart-Center! ::)


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Ki44LvR on September 01, 2016, 08:44:52 AM
Hi Crabby, glad that the operation went well and thanks for the update. Glad you are back at the workbench too. The Chieftain is coming along - looks like a lot of work but I bet it will look lovely in the air. Have to say I admire modelers that take on twins- I have enough problems just building a single! Perhaps one day I'll try one as I've always wanted a mossie!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on September 05, 2016, 09:48:36 AM
Hi Jeremy,
I will share a secret with you. I feel great kind of like an unclogged drain. I am milking this "convalescence" so I can get caught up with my Navajo and some Twilight Zone episodes. Here is where I stand with the Piper. I stopped on the wing and built the nacelles so I could be sure of the rib location. Other than that its just measure and cut, on and on. I found a couple tubes of Duco in Melbourne. A nice thing about this plane other than when its finished, is there are tons of good color references on the web and at the airports. I have sworn off tissue printing for the time being. This thing is gonna be all hands, fingers and thumbs. The pics tell the story. I hate stick-boxes but you have to appreciate the design once you weigh in.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on September 08, 2016, 09:52:16 AM
For the test fit I pulled the "three fuses" off the board and arranged 'em on the wing to effect a similarity of a Chieftain, not too bad. I found out I was all out of carving block so I ordered a 3 x 3 x 12 from an Amazon link... and got it in 2 days. So I will now focus on the nacelles, props and spinners. I am thinking about how to adapt my typical hidden free-wheeler for a three bladed prop. The spinners may be too narrow for that and I may do the brass tube affair all the way through...stay tuned. Never having done a twin I chose this one because it looked simple. Simple is one thing, easy is quite the other.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on September 09, 2016, 12:23:55 PM
here is what the rear of the nacelles should look like


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: strat-o on September 09, 2016, 01:04:26 PM
I like this one.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on September 12, 2016, 11:06:37 AM
There is a void in the plan concerning this area. There will be some light fiddling about coming up.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on November 02, 2016, 09:57:40 AM
Ok I am back to minding my own business, and working on the Navajo...I got tired of avoiding planes with spinners, and bought a new-old time drill press, and a new old-time table saw here in Palm Bay where the funeral and garage sale is the thing to do. So I am here spinning up a few spinners for the Navajo, the Heinkel, the Spitfire, and my Peck Mustang. I regret that I am a creature of spasm, and build in convulsions! I can see the end of the tunnel here though. I want to fly this thing at King Orange.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: tom arnold on November 02, 2016, 10:29:05 AM
Crabby you will love your drill press and will make up spinners by the baskets just for fun. However, I have found that hard-backed sanding sticks can, on many occasions, give you an oval shaped spinner as opposed to a nice round one. It does not happen all the time but seems to be dependent on the spot wood density and once it starts that hard-back sander quickly makes it worse with no remedy. It also may have something to do with the speed the work is run at. In my experience and as COUNTER-intuitive as it seems, a folded piece of sandpaper always does the job perfectly. I go 60# to 100# to 220# grit. Good luck in any case.

I was around when Dick Howard first brought out his Navajo to fly and in spite of it looking like a station wagon with wings (actually the real one was!), it was a terrific flyer. I think you will really enjoy it at the field.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on November 03, 2016, 01:20:47 AM
Tom yep you got that one right! The first one came out really well the second on was a flop!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on November 03, 2016, 09:54:21 AM
Tom, that was great advice. All is well now. I have always had spotty results with turned spinners, and never thought that it could be the sanding implement. Yeah, I go from course to fine and get a pretty good finish.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Glenn (gravitywell) Reach on November 03, 2016, 03:07:44 PM
I've had the same thing happen and actually gave up trying to turn a spinner!  I'm going to give the sanding paper method a try and hopefully get baqck to turning them, thanks for the tip. :)


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: USch on November 03, 2016, 05:31:48 PM
I turn my spinners with a, as you call it, hard sanding block.
I think that if the result is a not true, round spinner, then you apply to much pressure during sanding. As most of you, also my rough, balsa-plywood spinner block is not at all round, but is just hacked out of balsa sheet and glued together. So if you apply to much pressure you follow actually the original shape and you dont cut of the high points.
So especially at the beginning of sanding you should only rest the sanding block lightly against the turning block, not applying any pressure. In this way you cut off the high spots. Even in the following up to finish the shape I do never push hard against the spinner to not cut off the soft spots. Remember that balsa sand's more easy with the fibre and less so at 90°. In this case, if you push hard against the turning spinner, you will take off more material where the fibre is parallel to the sanding block and less when the fibre is perpendicular to it.

Just my 2 pence worth,
and I admire you guys building multi-engine rubber models  ::)

Urs


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on November 07, 2016, 04:55:49 PM
As you may well have gathered I am not in any particular rush to get this build done, and everything I do borders on obsession. This weeks obsession is the mandrel. I have a second-hand drillpress and have been making mandrels from 2" screws and washers and they all turned out really bad and my spinners really sucked! The thing is I have two complete dremels and the cut off bits are perfect for what I am doing. My regrets to Bob (Modelace)! I now have two perfect scale spinners but I really had to learn it myself! I really want to devise a good mandrel for my drill press though.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on November 10, 2016, 09:20:27 AM
Some slight progress, after getting over my mandrel/spinner obsession. This is a very simple build and can be knocked out a lot quicker than I am doing it. I glued my spinners to the nacelles and rouuuugggh sanded the cowls to blend in best I could. Here is where I will reinforce my motor peg holes and look for crooked spots etc. Never having attempted a twin, I will need to hear comments and such from those who have. I am going to go for the tube/dowel config for the motor peg, and am considering using my Crabbyized prop shaft motor clutch for the free-wheeler. At this point, Mike Midkiff's basswood pop sickle stick prop blades are in vogue in my brain. I have to watch my weight. Everything is getting hollowed out! Question: should I just go ahead and throw in the neg 3 degrees downthrust or wait and do it at the field?


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on November 10, 2016, 09:31:31 AM
Hi Urs.
You are so right about the grain direction when spinning balsa...So, I got the idea to glue my blocks together cross-grained then spun 'em with my dremel which is a lot faster than the drill press. Anyway the next time I do a spinner from a one-piece block I will start with the grain going base to point, and won't have to deal with perpendicular grain causing hard spots at 180 degrees! Thanks for the clarity there!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: USch on November 10, 2016, 10:29:13 AM
....from a one-piece block I will start with the grain going base to point, and won't have to deal with perpendicular grain.....

But then the spinner splits easier and the spinner is the first thing hitting....if ever  >:(
There's always a drawback, however you do it  ;)

Urs


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: tom arnold on November 10, 2016, 10:33:27 AM
Every model I have ever dragged to the field needed at least 3 degrees down so I always pat myself on the back if I have a little cranked in. I have never worried about side thrust on twins as I just give the right prop a bit more downthrust to stop a torque roll.

Sidethrust on twins is almost a needless complication. The right hand nacelle, because of the side-thrust-line offset, wants to drag the plane to the right, which does not help counter a torque roll. The right hand side-thrust prop blast does help in that it flows against the vertical stabilizer and acts like right rudder. The left hand nacelle side-thrust wants to push the plane's nose to the right which does act like a rudder against torque but the prop blast has no effect on the vertical tail. As a result, it is kind of delicate dance and you are not sure what is helping or not. The configuration of a twin even comes into play with a single vertical tail or twin tails as to what gets pushed around by what prop. The downthrust on the right engine gives you everything you want and is very predictable and precisely adjustable, or at least that is my experience.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on November 10, 2016, 12:36:07 PM
Tom am I hearing the the right nacelle only ought to have downthrust? Also I am getting two schools of info as to counter rotating props...Most guys seem to want to use counter-rotators, but others such as my Dad, have them both spinning same direction... how do you make a call on this?


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: tom arnold on November 10, 2016, 01:47:50 PM
Oops. Maybe I mispoke. Both nacelles should have downthrust adjustment and to control a torque roll, I give the right nacelle a bit more downthrust.

As far as counter-rotating props, I have heard 2 sides to the argument and I have done both.

1. FOR: By having counter-rotating props, you eliminate one of the biggest problems in trimming and that is the torque roll. Once you get your twin trimmed the way you want it to fly, you can crank in the winds until the motor is drooling lube and that baby will do nothing but climb. Disadvantages are that you have to make your props, remake them when they bust, make sure your Z-hooks go in opposite directions or the motor will climb off, and remember to wind in opposite directions.

2. AGAINST: Every other airplane you build and fly, you learn how to contend with torque and use it to guide the flight path. Why should a twin be any different? Torque is easily controlled by giving the right more downthrust. No worries about winding the wrong way, mixing up the Z-hooks, you don't have to fabricate your own props, and the store bought props are relatively easy to replace. Disadvantage is you have torque to contend with.

I have seen excellent modelers (Chris Starleaf, Tom Hallman, Dave Rees....) do both with twins and it does not seem to be an issue as to how easy the model is to trim or flight times. I did #1 for 20 years and made everyone of the mistakes noted numerous times! I finally went to #2 as I got tired of fabricating props and Peck props are relatively easy to repitch to anything I want. I also started building to a specific power-prop combo and would size my twins to match that combo rather than build the airplane first and then try to match a prop to it.

Both work and it is really just individual preference.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: ironmike on November 10, 2016, 02:59:12 PM
Actually I do contras because (in my experience)
contras otbd over the top seem to require less down thrust
than other power control methods. Inbd/outbd over the top
or same direction. Pick yer poison.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: ZK-AUD on November 10, 2016, 06:35:27 PM
If I could just go back to the oval spinners for a minute this is one of those phenomena that just ruin you whole life when it happens.  Once they go off round (due to the reasons already mentioned) that's generally it.  The process is similar to the enlargement of a pothole or corrugations in a road once it starts.

The problem is that if you imagine your drill press as a metal working lathe and your hand as the tool post, you have a situation where the tool post is going in and out with the work!

I have had much better success with making a profiled sanding block with the sandpaper taped to it with double-sided tape.  I use a big block as the greater mass keeps it flat and is easier to prevent movement.

Also pays to check the bearings on your drill press for side play!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: tom arnold on November 10, 2016, 11:39:15 PM
I forgot one other thing that has given me egg spinners in the past----the shaft or mandrel. I spin my spinner blanks on a Moto-tool and use a steel drill bit glued in the block of balsa as the mandrel. I used to use short lengths of steel rods around 1/8"diam and up and I found no matter what brand I used that eventually they would bend ever-so-slightly, sometimes not even enough to notice unless I rolled the shaft on a flat surface, and it messed up every spinner after that. I switched to actually gluing into the balsa blank the drill bits that I drilled the initial hole with. They are hardened steel and will never bend and after twisting and extracting from the finished spinner, I run them through a wire brush wheel on a grinder to whip the dried glue off and use them again. That may dull the drill bit but it spends it's life only going through balsa so it doesn't matter. They are cheap too.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Warhawk on November 14, 2016, 08:41:19 AM
I made a lathe out of a 7.2v Dremel to address the egg-shape and shaft bending problems.  I use several concentric pieces of brass going into a holder block that slides front and back, which holds the shaft steady.  Then it's a matter of sanding reasonably gently. . .   The nice thing is that I can remove the Dremel and use it elsewhere when I'm not turning round things like cowlings, wheels, and spinners.

Justin


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: BillE on November 14, 2016, 01:29:46 PM
Just a thought to add to the spinner discussion. I make wheels and spinners on a small metal-turning lathe and I have been woodturning for decades as a hobby.

What I have found is that to keep the object circular you need to keep the tool firmly against a fixed rest. If the tool is allowed to vibrate/wobble then the work starts to get a wavy finish, which in a small diameter would look oval. Once you have got these ripples it is quite hard to remove them - you have to take very light cuts of just the "crests" of the waves.

For turning balsa I use slim wooden sticks with abrasive paper glued onto them and keep the stick firmly resting on the tool rest. To test for circularity touch the top of the item lightly, as it is rotating, with a smooth piece of wood or metal to see if it rattles.

Obviously if you are using a drill press the whole process is on its side so the rest arrangement would have to be a vertical face and you would need to apply side force to keep the tool in contact with the rest because gravity is not helping you.

I hope this helps.
Bill


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on November 20, 2016, 03:55:01 PM
I stopped the airframe and got focused on my spinner/nose block situation. I am gonna use my Crabby freewheeler. Here are the pieces...I am gonna do contras...I bent an "S" and a "Z" hook and will have to mind my winding, when the time comes!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on November 21, 2016, 09:07:23 AM
I switched to actually gluing into the balsa blank the drill bits that I drilled the initial hole with. They are hardened steel and will never bend and after twisting and extracting from the finished spinner, I run them through a wire brush wheel on a grinder to whip the dried glue off and use them again. That may dull the drill bit but it spends it's life only going through balsa so it doesn't matter. They are cheap too.
Tom what glue are you using here?


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: tom arnold on November 21, 2016, 10:27:11 AM
I use thick CA and only on the shaft near the base of the spinner. To remove the shaft, I twist it carefully out with a pliers and a chunk of dried glue and balsa comes out with the shaft. However, there is plenty of an aligned  "hole" left in the spinner should I want to bush it with tubing or whatever.

 I usually drill completely through the spinner block and put a ramp style freewheeler at the tip mostly because I have a heck of time trying to align a smooth spinner on a prop shaft and prop. That's just my hamhanded shop work, I admit.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on November 29, 2016, 09:46:15 AM
Here's the nacelles...very simple things in comparison to Prospers Whirlwind, but I am looking into making them removable for winding. It just makes sense to me. The free wheelers are inside the spinners and consist of a half round brass tube that clutches the aluminum where the prop blades will be glue later. When the rubber relaxes the prop slides back to the bearing and free wheels. Minimal soldering involved.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on November 29, 2016, 09:55:36 AM
Just to be fair here's a look inside at what I do for freewheelers. It works well for me. Some guys cry easy gets harder every day, but I like to make mousetraps!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Prosper on December 01, 2016, 01:43:33 PM
Quote from: Crabby
Here's the nacelles... I am looking into making them removable for winding. It just makes sense to me.
It looks like a good candidate, Crabby. If I understand the plan, the nacelles slot onto the mainspar already, so you just need some extra anchors somewhere to take the place of glue. These nacelles look well-protected from landing shocks to me. The main engineering issues with detachable nacelles as far as I can see are whether they permit an equal freedom for the rubber motor and whether they can absorb landing shocks or pass landing shocks into the airframe as well as a glued-on nacelle would. The only other thing here is that the nacelle glued to the wing looks like it would add a lot to the wing strength itself, so the removable nacelle would have to cover this to or the outer wing might fold in a tip-strike. That's if I understand the plan. I reckon whatever pins or clips or slots you used for you anchors would cover this.

Regards,
Stephen.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on December 01, 2016, 03:04:21 PM
Stephen, Thanks for looking in, and you brought up a good point. The nacelles, now that I think of it are a major part of the structural integrity of this wing. Without it on board we have a leading edge, a spar and a trailing edge, doing the job alone. I am going to have to engineer some strength in there, A tip strike would send me back to the shop. But after seeing your Whirlwind I am stuck on the idea of removable nacelles. Some guys will say "build for the flight not the crash" I have to make a reasonable compromise.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on January 02, 2017, 10:34:47 AM
Well King Orange came and went and I was too busy in the Christmas window to play with this thing. This airplane was not ready obviously. So...I am still fiddling around and everytime touch it I break a $#@$%^ stick somewhere! Here are a few pics of another throw-together with the spinners on and the nose nice and pointy. I think the rudder and stab are next in line. Still pondering the removable nacelle question.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on September 25, 2017, 10:15:56 AM
Getting my guns loaded to try and finish this thing off. FlyAce I sent you a clear as mud description on how I did the spinners, Check out the last 20 or so posts to get a look at some pics. After the long period off I found my nacelles aren't exactly nesting onto the wings anymore, so I am gonna set that aside and get going on the rudder and stab. Of course I did the usual and didn't leave enough room in the rear of the fuse for stab adjustment, so I gotta open that gap. Covering the fuse, I am thinking about using 1/4 mil acetate then going over it with esaki. This will take care if the glasswork in the cabin area. I may do the wings this way too unless anyone has a gripe over it. I have to fly in the am here where the dew has its way with standard tissue covering.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: MKelly on September 25, 2017, 01:07:33 PM
Nice looking bones on this one, Crabby.  I appreciate the insights on your spinners and free-wheelers - I think this is the next technical area I need to work on to improve my modeling.  Looking forward to seeing your progress and hearing how your Piper flies.

Cheers,

Mike


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Don McLellan on September 25, 2017, 03:09:03 PM
Hi Crabby,

Great that you are back working on this model.  I too am looking forward to seeing your progress.

Don


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: strat-o on September 25, 2017, 04:02:11 PM
I'm interested in your covering choice.  How will you adhere it?  With Balsaloc/heat activated adhesive?  I assume it's heat shrinkable?

Marlin


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: flydean1 on September 25, 2017, 08:47:15 PM
Really looking forward to seeing this one fly.  I taught the Navajo for nearly 6 years.  It's really my favorite.  Sorta like a good old Ford Explorer.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: faif2d on September 25, 2017, 10:47:29 PM
I had good luck using a disk sander to remove material from a drill turned block.  The drill turns against the direction of the sanding disk.  I turned this rather slowly (variable speed drill) until the oversize block was smooth.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on September 27, 2017, 10:10:12 AM
Marlin, I have been long an Esaki guy and have no experience with mylar. My research reveals the use of a tacking iron to apply and shrink. The adhesive? I have read of a few different approaches. The forum is open to whoever wants to shed some clarity on this.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: strat-o on September 27, 2017, 02:07:03 PM
I found this reference and I think it's pretty great, BUT NOTE--It's describing mylar or polyester film: http://www.thebuildingboard.com/2012/05/tissue-over-mylar.html

It's a single "mile-long" paragraph describing several modelers experiences in how to do it right.  They use contact cement obtained at a fabric store.  One thing I think is cool is they say that tissue over mylar can weigh less than plain tissue due to requiring less coats of dope.  Personally, I never go beyond two coats so...YMMV.

It got me thinking about how one might cover in clear mylar and then use different color tissues to make a two-tone camouflage pattern without much overlap.  Also this approach would benefit me living in the hyper-humid environment that I do (Houston).

Ooh, ooh! one of my favorite models is the Ki-61 Tony.  One interesting color scheme is bare aluminum with green camo spots.  I bet it would be interesting to do chrome mylar for the base and tear up some camo spots out of O.D. tissue!



Sorry, returning the thread-killer mantle back to you, Crabby!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on September 27, 2017, 06:54:10 PM
Thanks strato... sorry I have stopped more threads with one dopey comment. You will never have to worry about being a Thread-Killer as long as I keep making irrelevancies on a regular basis. Thanks for the link however! I am gonna take my time on this. I am sick of seeing my models cartwheel their way to hell's torture gurney!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: fred on September 27, 2017, 10:27:30 PM

 a) I found that Balsa spinners can be a Pain to turn.
 Blu Foam works better/more faithfully.
 Now I turn spinner plugs out of Gelutong.  Very nice fine grained stuff. Using the table of my Drill press as a tool rest.. always... or eggs result, as noted often above
 Then I use the gelutong plugs to vacuform spinners in Styrene. Thickness of which is dependent on spinner depth. Light durable results.
 b) I use laminating film.. Often called Doculam ... 3000' x 12" rolls for only a few $ at a local supplies shop
 I have 1.2 mil and 1.7mil PET on hand. Dunno what that translates into in um But it seems as thinner than Tissue.
 Irons on, as it has an inbuilt adhesive, just like most Iron On films used in RC model building.
The stuff comes as milky white but heat turns it crystal clear (instant windows !)
It's surprisingly tough/puncture proof stuff.
 Takes paint... after a Vinegar wash down.
 Experiment ?
 


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: fred on September 28, 2017, 12:37:56 PM
Small addendum;
 Read that some have used plastic shop bags as handed out at Wally mart (crinkly plastic ones)
  Purple Glue stick on balsa frames then a covering iron to  apply the film and heat shrink it.
It forms beautifully to compound shapes.
Only issue seems that being a polyethylene variant, painting it is 'tricky'


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: rgroener on March 22, 2019, 01:28:53 AM
Crabby, any news on this project? I check from time to time to see if there is some progres, but unfortunately there is none. I am looking forward to see it finished and flying. Hope that you will post some good news of it.

Roman


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on May 11, 2019, 11:18:02 AM
Hi Roman! Thanks for checking in! Here hangs the Cheiftain. Sorry I missed your message! Its (as Don McLellan) says 90% finished and 90% to go. I just re-read the entire thread. Good gravy. I therefore apologize for getting everyone all excited then losing my mojo! They make viagra for a similar problem. I must say the Chieftain is starting to get my attention again, as is the Wildcat hanging next to it. I am going to look around for this Doculam fred is talking about. I am feeling comfortable with mylar covering and think its really fun and quick. I did find that floral paint adheres to mylar, but masking it for another color is sketchy, as it will pull the first coat off. Vinegar fred? I am glad I re read your post!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: rgroener on June 09, 2019, 11:08:47 AM
Crabby, good to hear that your interest in the Chieftain ist growing again.
Popcorn is ready to follow your next move in this build.

I printed out the plan in full size and looking at it from time to time. Your build could inspire me to start it too ;D

Roman


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: faif2d on June 09, 2019, 12:33:13 PM
Amazon has Doculam.  27" x 500 ft is $35 or something.  We used to use it for combat planes, worked good but the glue was not very fuel proof.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on June 09, 2019, 12:38:06 PM
Good am Roman,
Funny you should respond today. I was out on my morning walk and found this drone out on the curb for pick up turns out it has two sets of counter-rotating props...I began thinking of Matthew (Lemeul) and his Lancaster build over on SFA, (years back)  the build seemed to stall as soon as he couldn't find a set of counter-rotators on the market. But these would fit the bill. Unfortunately he seemed to had shelved the project. But they are 5 5/16" diameter which makes 'em perfect for the Cheiftain! They are very fine pitch and tapered some so maybe they wont work but I'll die trying! (Not really) I never thought to pick up any of the dead drones I see from time to time, but they are a good source for counter rotators!


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Dan Snow on June 09, 2019, 02:25:53 PM
I wonder if you could use heat and change the pitch on the blades?


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: Crabby on June 09, 2019, 05:13:38 PM
Dan no doubt there, but I am still gonna make a set of Mike Midkiff popsickle stick blades for this thing.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: FLYACE1946 on June 10, 2019, 12:35:47 PM
Please show us how those props turn out.


Title: Re: Dick Howard Piper Navajo Chieftain
Post by: rgroener on June 11, 2019, 01:38:54 AM
Crabby, good idea... I know these drones must be good for something ::)

In one of the early post you asked for the article. Not sure if you got it in the meantime... But if not, here it is at the bottom of the page:

https://outerzone.co.uk/plan_details.asp?ID=1326 (https://outerzone.co.uk/plan_details.asp?ID=1326)

I am nearly ready to start this ship by myself. This way, I could surf on the inspiration wave of your build 8)

Roman