Author Topic: New Electric Twin project back on track (Read 116463 times)

David_Stack · « **Reply #350 on:** December 04, 2013, 06:23:21 PM »

Good Evening Bob;

You said that flotation foam 'carves like butter...' Curious, did you not try and hot-wire cut it? I would think you could fabricate bulkhead templates at the front and rear of the turtledeck (for example) and cut it out in short order. Does it not cut well?

No concerns about it not providing the necessary torsional stiffness that a molded balsa deck would (or is there additional structure in the fuselage to compensate for any structural rigidity lost due to the foam)?

r/
Dave

Bob Hunt · « **Reply #351 on:** December 04, 2013, 06:36:49 PM »

Hi Dave:

The Flotation Billet foam hot wire cuts extremely well also. Cutting compound curves with a hot wire is another story entirely...

This foam works so easily that I could virtually carve and sand the entire fuselage by hand in the time it would take me to make front and rear cutting templates for a straight taper block... These blocks have pronounced compound curves; especially the top block in the canopy area.

The flotation foam is extremely rigid when the coat of epoxy has been applied, and further bracing of the fuselage would probably not be necessary. Having written that, we did install cross-grain 1/16 balsa in alternating 45 degree patterns on both the top and the bottom of the fuselage crutch after the wing and tail were installed and the controls hooked up. That step made the fuselage extremely stiff, and the foam blocks just enhanced that rigidity. Trust me, this fuse will not flex or twist under load.

Later - Bob Hunt

Bob Hunt · « **Reply #352 on:** December 04, 2013, 07:32:04 PM »

The first photo here is a photo of the nacelle treatment. There are at this point two sets of nacelles. One has the thrust line on the centerline of the wing and the other has it 1/2 inch below the centerline of the wing. Yes, we remembered to make the prop clearance using the lower ones...

The other two photos show how the nacelles fit into the nacelle stubs that are permanently affixed to the wing.

Later - Bob Hunt

Shawn Lenci · « **Reply #353 on:** December 04, 2013, 08:58:52 PM »

Bob...Not sure those wheels are going to roll to well with all that wire hanging down.....

Shawn

wwwarbird · « **Reply #354 on:** December 04, 2013, 09:40:28 PM »

Holy smokes Bob, my brain hurts!

PJ Rowland · « **Reply #355 on:** December 04, 2013, 11:28:58 PM »

So you built a second second wind test bed ?

wow...

Howard Rush · « **Reply #356 on:** December 05, 2013, 01:31:10 AM »

This airplane looks suspiciously like a trimotor.

Bob Hunt · « **Reply #357 on:** December 05, 2013, 04:17:02 AM »

Howard: You are evil... I may have to adopt you.

Shawn: You are very observant; I'll look into that...

Still immensely enjoying the Jackson Browne concert DVD you sent me.

Wayne: I supply aspirins free of charge with my posts...

PJ: Wait until you see the proof of concept twin we are building to ensure that the testbed will work...

Bob

Mike Ferguson · « **Reply #358 on:** December 05, 2013, 04:44:18 AM »

Quote from: Bob Hunt on December 05, 2013, 04:17:02 AM

PJ: Wait until you see the proof of concept twin we are building to ensure that the testbed will work...

This is suddenly turning into stunt's version of the movie "Inception"!

Outstanding work as always, Bob.

Bob Hunt · « **Reply #359 on:** December 05, 2013, 04:55:21 AM »

Hi Mike: If only I had Leonardo DiCaprio's hair... $:-\$

How's your Crossfire project going?

LAter - Bob

john e. holliday · « **Reply #360 on:** December 05, 2013, 07:50:06 AM »

Hey Bob, I don't worry about hair any more as it seems the females like the bald look. Also don't have to worry about it blowing into my eyes while flying. By the way, you guys are geniuses. I like the removable motor mount.

Keith Renecle · « **Reply #361 on:** December 05, 2013, 08:59:13 AM »

Hi Bob,

Thanks for all of the finer details on the power package and props. I love the test-bed idea and the way you've constructed it. I'm really excited now to see the tests and of course the final twin project flying!

Keith R

Dan Bregar · « **Reply #362 on:** December 05, 2013, 05:21:24 PM »

Hi Bob

You used to be a very talented young man. Now your a very talented mature gentleman.

Thanks for sharing all that you do. You inspire lots of people

The Hunt Skunk Works is going strong as usual. You are the best.

Dan

MarcusCordeiro · « **Reply #363 on:** December 05, 2013, 05:24:58 PM »

Well, let's sing the soprano then...

Amazing Bob!

Marcus

Rodrigo Mansano · « **Reply #364 on:** December 05, 2013, 05:29:11 PM »

Marcus, when Bob told us that it was a test bed... i really thought that the blue stuff was not intended for moulding.... after that i almos saw some balls freeeeeeee but the soprano thing was the bestttttt

MarcusCordeiro · « **Reply #365 on:** December 06, 2013, 05:33:35 AM »

Quote from: Rodrigo Mansano on December 05, 2013, 05:29:11 PM

Marcus, when Bob told us that it was a test bed... i really thought that the blue stuff was not intended for moulding.... after that i almos saw some balls freeeeeeee but the soprano thing was the bestttttt

You better keep this story under wraps, or instead of balls, some wires will get cut, like the ones from the bzttery in a certain model???

Marcus

Rodrigo Mansano · « **Reply #366 on:** December 06, 2013, 06:34:54 AM »

Keep calm Marcus, I´ll keep it with me.... I don´t want my model batteries wire to be cut.......

john e. holliday · « **Reply #367 on:** December 06, 2013, 09:03:47 AM »

Now you've both done it. We need the rest of the story now.

Yes Bobby Hunt is a genius when it comes to stunt planes, but he listens a lot to other ideas. He has a lot of great friends to keep him on track. Can't thank Bobby enough for his contributions.

Bob Hunt · « **Reply #368 on:** December 06, 2013, 05:58:20 PM »

Hi Doc:

Marcus bet a couple of vital spherical body parts that the blue foam pieces depicted on the testbed twin were actually mold bucks and not actual "flying" parts. Well... he lost that bet; those are "flying" parts... I pointed that out to him in a subtle fashion, and his friend, Rodrigo, is making Marcus's life a bit miserable over his lost whimsical wager. All in fun, of course...

Thanks, Doc, for the very kind thoughts. I appreciate them, even though I have never felt anywhere near a genius. Just trying to make logical decisions and try as many new things as the time I have left on this orb allows. I am more than glad to share any findings that might help or inspire others. Call it "paying forward" of that which was given to me.

Later - Bob

MarcusCordeiro · « **Reply #369 on:** December 07, 2013, 07:36:53 AM »

Yeah, never jump to conclusions...

Bob, you really tricked me...

Marcus

Bob Hunt · « **Reply #370 on:** December 08, 2013, 07:51:49 PM »

Got a bit more done on the testbed twin this weekend. The motors are mounted (yeah, I know, big deal...), the retracts have been mounted and the struts sized and the wheels installed, the hatch holdowns have been installed and I painted on a simulated canopy to give this thing some shape.

If everything goes as planned - and the weather cooperates - we will fly this monster later in the week. Pretty cold and wet outside right now... $:-\$

Later - Bob Hunt

55chevr · « **Reply #371 on:** December 08, 2013, 08:16:02 PM »

Looks fast sitting still ...

Joe

Air Ministry . · « **Reply #372 on:** December 09, 2013, 06:27:37 AM »

Looks like it might do something .

Rodrigo Mansano · « **Reply #373 on:** December 09, 2013, 06:42:03 AM »

This "testbed" is much better lookint than my models! Congrats Bob, and good luck!

Bob Hunt · « **Reply #374 on:** December 09, 2013, 08:03:55 AM »

Thanks Joe, Matt, and Rodrigo!

This has been a fun project for Buddy Wieder and me. We've learned a lot already about how to make an electric powered twin, and I'm sure there is a ton of stuff yet to discover. As they say, "The longest journey begins with a single step."

Bob

john e. holliday · « **Reply #375 on:** December 09, 2013, 08:15:22 AM »

Looking at the pictures of the plane without paint using the different materials, I kind of like the color scheme that has come about. I know it has to fly great as two of the best are getting there heads together on this. I like it as it sets.

Bob Hunt · « **Reply #376 on:** December 09, 2013, 08:31:05 AM »

Hi Doc:

Yeah, it has a certain business-like look about it without a "real" finish. With a bit of thought, the carbon on the wing could be applied more neatly and yield a more pleasant "look." We started out with the idea of producing a very spartan-like ship that no one would ever see. It was to be a pure testbed, but as we got going on it, several new ideas popped up, and it just sort of evolved into what you see in the photos. It will make a great motor/timer/ESC/retract test machine, and hopefully it will fly well enough to give us some information as to what to keep and what to change on the actual competition twins, which are next to build.

I have the first twin (the subject of this thread...) in primer and it is almost fully sanded and ready for the ChromaSeal coat and then another sanding before the thin coat of color goes on. That one will for sure be ready for early spring test hops. Hopefully we'll also have the new twins ready for the season.

As my good friend, Dick Sarpolus would say, "Hey, Twins are fun!"

Later - Bob

Avaiojet · « **Reply #377 on:** December 09, 2013, 09:02:05 AM »

Bob,

Nice project! Great lines, good looking airplane!!

Spinners!?

You have two nice ones there.

Please, what size are they and where did you get them?

Charles

Bob Hunt · « **Reply #378 on:** December 09, 2013, 09:35:11 AM »

Hi Charles:

The spinners are Tru-Turn 1 1/2-inch diameter units with cuts in one cone for tractor props, and cuts in one for pusher props. This will allow me to try two different rotation schemes. I plan on purchasing another set of spinners just like the ones I have, and that will allow me to experiment with both props turning in the same direction, or in different directions and all the permutations available. I want to know once and for all what configuration is best for our purposes (or at least for my twin designs...).

Later - Bob

Robby Hunt · « **Reply #379 on:** December 09, 2013, 03:53:19 PM »

Quote from: Bob Hunt on December 08, 2013, 07:51:49 PM

If everything goes as planned - and the weather cooperates - we will fly this monster later in the week. Pretty cold and wet outside right now... $:-\$

Later - Bob Hunt

I may get to see the maiden voyage after all!

Tom Niebuhr · « **Reply #380 on:** December 10, 2013, 11:27:53 AM »

Bob,
Even the test bed makes the Tucker on the wall look like it is 200 years old. Your inputs are sure helping me myMcDonnell Banshee project.

Dan Bregar · « **Reply #381 on:** December 10, 2013, 05:35:33 PM »

Dear Mr. Hunt

Very, very cooool ! Lots & lots of potential to say the least.... We are all staying tuned for further reports. If it ever warms up you could fly it pretty soon, no ?

Bob Hunt · « **Reply #382 on:** December 10, 2013, 05:49:03 PM »

Dan: Yeah, it's almost ready to fly. I just have to run a few wires and do some test run-ups before heading for the field. I write a flight report here as soon as we fly it. There are a number of people getting in line here to get some handle time of this one. I predict that we will be seeing a lot of twin electric powered models in the near future. Heck, there are two more starting construction here this week in my shop alone!

Tom: That Tucker has been renamed. It's new moniker is "Frankentucker." It has a new electric nose and a new flap (the old one had a curl in it that was making trimming a nightmare. It's working way better now! Robby has taken custody of this ship and he's flying it very well indeed. He's due back from college for Christmas break later this week. Hopefully we'll get enough good weather to fly the twin and have him put a few patterns on Frankentucker.

Glad our experiments have helped on your Banshee project. Lots of new ground to break...

Later - Bob

Crist Rigotti · « **Reply #383 on:** December 10, 2013, 07:20:31 PM »

Wish I were closer to you so I could to get in line Bob. Watching real close. Of course a smaller ship would fit me better! Go get 'em Bob.

Glad to see Robby will be home for Christmas and get some handle time.

Bob Hunt · « **Reply #384 on:** December 10, 2013, 07:28:16 PM »

Hi Crist:

You are in luck; the next twin (after the ones Buddy and I just started building...) will be a classic 35-size ship with two smaller motors and no retracts. The really neat thing is the world of new designs that has been opened by twins. We have a couple of really slick new ones drawn and lots more in the idea stage.

Later - Bob

Crist Rigotti · « **Reply #385 on:** December 10, 2013, 07:38:22 PM »

Quote from: Bob Hunt on December 10, 2013, 07:28:16 PM

Hi Crist:

You are in luck; the next twin (after the ones Buddy and I just started building...) will be a classic 35-size ship with two smaller motors and no retracts. The really neat thing is the world of new designs that has been opened by twins. We have a couple of really slick new ones drawn and lots more in the idea stage.

Later - Bob

Wahoo!

jfv · « **Reply #386 on:** December 12, 2013, 10:51:11 AM »

Hi Bob:

I have been following this thread closely and am intrigued by the design and the methods of construction. While the idea of using this minimalistic construction for a test airframe is great, I believe that, as an unintended consequence, for those who might like to try their hand at designing or scratch building, the construction methods offer a really wonderful way for them to get started. In fact, I have been inspired by your Joe Nall Cadet minimalistic construction to design a new profile using a similar technique. Keep up the fine work.

Bob Hunt · « **Reply #387 on:** December 12, 2013, 02:06:24 PM »

Hi Jim:

"Unintended consequence?" Perhaps you meant, unintended benefit, or unintended bonus...?

I totally agree, and I'm well into the project of bringing the Joe Nall Cadet - and other beginner/intermediate designs to fruition as semi-kits that use the "Lost-Sheeting" method of building. It's light, quick and inexpensive!

Later - Bob

ptg · « **Reply #388 on:** December 12, 2013, 02:14:27 PM »

This is a 'sport flyers' dream construction. As you know I will soon do something similar for my (Ahem

) RC designs.

Air Ministry . · « **Reply #389 on:** December 13, 2013, 02:58:18 AM »

HOWS the WEATHER .

" You are in luck; the next twin (after the ones Buddy and I just started building...) will be a classic 35-size ship with two smaller motors and no retracts. "

are we allowed guesses .

?

55chevr · « **Reply #390 on:** December 13, 2013, 08:30:36 AM »

I have 2 young student pilots that would benefit from the JN Cadet ... These will build well especially with Bob Hunt's wing cores and electric power ... want a couple when they are available.

Joe

john e. holliday · « **Reply #391 on:** December 13, 2013, 08:48:53 AM »

Quote from: ptg on December 12, 2013, 02:14:27 PM

This is a 'sport flyers' dream construction. As you know I will soon do something similar for my (Ahem ) RC designs.

Egads, don't tell me you are going to the twiddly sticks of model planes?

Well I did play with them for a few years until I got bored and started flying CL more often.

wwwarbird · « **Reply #392 on:** January 09, 2014, 09:45:22 PM »

Quote from: Bob Hunt on December 08, 2013, 07:51:49 PM

If everything goes as planned - and the weather cooperates - we will fly this monster later in the week. Pretty cold and wet outside right now... $:-\$

Later - Bob Hunt

Well?

Bob Hunt · « **Reply #393 on:** January 10, 2014, 06:48:39 AM »

Well... It's still pretty cold and wet outside!

Bob

55chevr · « **Reply #394 on:** January 10, 2014, 09:33:49 AM »

Bob,

It is warm and wet inside at the job. The warming temperatures are thawing the frozen and cracked pipes in the sprinkler system.

Joe

Duke.Johnson · « **Reply #395 on:** January 10, 2014, 10:34:20 PM »

Hey Bob
Is this the Cadet you mentioned when we talked? I've never built a swept LE wing, might be beyond my building ability. It is a cool looking plane. My son and I were wondering when you might have the kits ready and how much they are going to cost.

Bob Hunt · « **Reply #396 on:** January 11, 2014, 10:33:38 AM »

Hi Duke:

There is no "building" really to be done on the wing; it's a foam core. Piece of cake! I'm hoping to find some time this month to finish the plans and get the semi-kit ready for market.

Later - Bob

Duke.Johnson · « **Reply #397 on:** January 11, 2014, 07:58:06 PM »

Thanks, I'll keep my eye on this thread

Larry Wong · « **Reply #398 on:** January 26, 2014, 08:59:58 PM »

Bob How or what do you use to apply the carbon matt. to the foam?

David_Stack · « **Reply #399 on:** January 27, 2014, 08:22:16 AM »

Good Morning Larry;

Back in post #354, Bob discusses the construction of the wing, what her terms his "Lost-Sheeting method"

Requoted here:

"We used the same technique to build the wing for this testbed model as we did for the Joe Nall Cadet models. We call this construction the "Lost-Sheeting method." There is no balsa sheeting on the wing. The wing is a solid foam core made from 1-pound density foam. There is a slot cut in the center of the wing cores to allow the leadouts to get to the tip and have some adjustment. There are slots cut into the top and the bottom of the wing at the high point to accept 1/2 x 1/8- inch basswood spars. The spars run the full span of the wing. There are several shear webs imbedded in the core between the spar slots to prevent the spars from "racking." That is the technical term for what the spars want to do on either side of the wing during maneuvering. In an inside maneuver the top spar in in compression and the bottom spar is in tension. If there were no webs between them, they would try to "clap hands" under stress. The webs prevent the spars from trying to move and hence impart a tremendous amount of strength. Enough not to break under maneuvering loads by themselves? Not quite. After the spars are glued into the slots and are firmly glued to the vertical grain shear webs, we apply .2 (two tenths ounce per square yard) carbon mat using water thinned Titebond wood glue. The carbon is first applied from the back of the spar on the top, around the leading edge and ends at the back of the spar on the bottom. A thin carbon strip reinforces the trailing edge area, and an additional piece strengthens the entire center section area."

r/
Dave

Author Topic: New Electric Twin project back on track (Read 116463 times)

Robby Hunt