Author Topic: New Electric Twin project back on track (Read 149838 times)

Larry Renger · « **Reply #250 on:** December 03, 2013, 08:31:43 AM »

I think that if you calculate the swept blade area for 4 8" props vs a single 14" prop, you will see why you need less total displacement. In addition, the smaller engines run at higher rpms, generally.

It calculates out that a 14" prop sweeps 147 sq.in. While four 8" props sweep 201 sq.in.

Keith Renecle · « **Reply #251 on:** December 03, 2013, 10:34:26 PM »

Thanks guys, I did realize that you can't simply add up the displacement, hence my question on how to work out what sort of power you need for multi-engine models. Larry's point on the prop swept blade area is also valid. In my next life I need to do an engineering degree! It will be interesting to see what motors, props and batteries Bob ends up with.

Keith R

Larry Renger · « **Reply #252 on:** December 03, 2013, 10:55:41 PM »

Another thing occurred to me, with a 14" prop the wash covers 14" of wing, with 4 8" props, it is 32", over double!

Tom Niebuhr · « **Reply #253 on:** December 04, 2013, 08:53:43 AM »

Bob,
Looking Good!

1) Why are the nacelle noses in two pieces and then ply plates over them?

2) I love the method of mounting a motor in the nacelle

3) The nose gear mounting looks great. I'll remember that for my McDonnell Banshee

4) The blue foam looked awful heavy, but it looks like the foam is hollowed out.

5) How are you going to finish it realizing that it only has to be sealed so it is protected from dirt?

Lauri Malila · « **Reply #254 on:** December 04, 2013, 09:58:21 AM »

That ship is powered by two 15's and is fitted with two 8.5-inch diameter props. It has effectively 17 inches of prop disk area..

Just being picky.. The disc area of 2 x 8,5" props equals disc area of one 12" prop.

Lauri

john e. holliday · « **Reply #255 on:** December 04, 2013, 11:00:42 AM »

This is beyond awesome. Is the Blue Foam Molding bucks or will they be glassed?

MarcusCordeiro · « **Reply #256 on:** December 04, 2013, 12:37:06 PM »

And then you get to see someone like Bob Hunt saying he's learned tons of stuff about building.
See the pics, and then start calculating how many eons it will take me to even come close...
Doc, i bet my b@lls it's for molding...
Hey Bob, you really make us look bad...

AWESOME!!!!

Marcus

Rodrigo Mansano · « **Reply #257 on:** December 04, 2013, 05:11:58 PM »

Bob, I think I had a intuition about the soprano thing....

Rodrigo Mansano
Brazil

David_Stack · « **Reply #258 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

Shawn Lenci · « **Reply #259 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 #260 on:** December 04, 2013, 09:40:28 PM »

Holy smokes Bob, my brain hurts!

PJ Rowland · « **Reply #261 on:** December 04, 2013, 11:28:58 PM »

So you built a second second wind test bed ?

wow...

Howard Rush · « **Reply #262 on:** December 05, 2013, 01:31:10 AM »

This airplane looks suspiciously like a trimotor.

Mike Ferguson · « **Reply #263 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.

john e. holliday · « **Reply #264 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 #265 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 #266 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 #267 on:** December 05, 2013, 05:24:58 PM »

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

Amazing Bob!

Marcus

Rodrigo Mansano · « **Reply #268 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 #269 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 #270 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 #271 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.

MarcusCordeiro · « **Reply #272 on:** December 07, 2013, 07:36:53 AM »

Yeah, never jump to conclusions...

Bob, you really tricked me...

Marcus

55chevr · « **Reply #273 on:** December 08, 2013, 08:16:02 PM »

Looks fast sitting still ...

Joe

M Spencer · « **Reply #274 on:** December 09, 2013, 06:27:37 AM »

Looks like it might do something .

Rodrigo Mansano · « **Reply #275 on:** December 09, 2013, 06:42:03 AM »

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

john e. holliday · « **Reply #276 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.

Avaiojet · « **Reply #277 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

Robby Hunt · « **Reply #278 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 #279 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 #280 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 ?

Crist Rigotti · « **Reply #281 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.

Crist Rigotti · « **Reply #282 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 #283 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.

ptg · « **Reply #284 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.

M Spencer · « **Reply #285 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 #286 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 #287 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 #288 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?

55chevr · « **Reply #289 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 #290 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.

Duke.Johnson · « **Reply #291 on:** January 11, 2014, 07:58:06 PM »

Thanks, I'll keep my eye on this thread

Larry Wong · « **Reply #292 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 #293 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

Larry Wong · « **Reply #294 on:** January 27, 2014, 08:49:45 AM »

Thanks I miss that part ,I guess water base paint would work ok.

Mike Ferguson · « **Reply #295 on:** February 14, 2014, 07:52:28 AM »

I blame Bob for the current Polar Vortex Snowpocalypse (TM) that's hit the Northeast.

Ever since you wrote that you were hoping to fly the twin testbed "in a week or so" in December, it's been nothing but snow, snow, snow ...

#kidding

Serious, hope you get to fly it soon, Bob ... and that good weather's around the corner.

Robby Hunt · « **Reply #296 on:** February 15, 2014, 10:01:29 AM »

Quote from: Mike Ferguson on February 14, 2014, 07:52:28 AM

I blame Bob for the current Polar Vortex Snowpocalypse (TM) that's hit the Northeast.

I blame all things vortex related on PJ.

wwwarbird · « **Reply #297 on:** March 25, 2014, 05:19:32 PM »

Any new news on the twin?

john e. holliday · « **Reply #298 on:** March 29, 2014, 08:31:07 AM »

I bet your foam supplier loves you> Great idea on the lining up the wing and fuse.

wwwarbird · « **Reply #299 on:** March 30, 2014, 08:45:36 PM »

Thanks for the update Bob, everything looks great. Waiting for some paint...

Author Topic: New Electric Twin project back on track (Read 149838 times)

Robby Hunt

Robby Hunt