RE: Gruman Ag-Cat  
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RE: Gruman Ag-Cat - 12/28/2007 8:11:04 PM   
outacontrol41


 

Posts: 1265
Joined: 11/27/2004
From: Girdletree, MD, USA
Status: offline 		Good workmanship...very impressive.

(in reply to mac49)
       Post #: 76

RE: Gruman Ag-Cat - 12/29/2007 7:13:57 AM   
anothercrashpilot


 

Posts: 124
Joined: 3/30/2007
From: Porterville, CA, USA
Status: offline 		........ .....VERY NICE INDEED ! ! ! .........I HOPE you get to spend MORE time on it and keep posting results ! ! ........... ........... The COLD evenings here and the Holidays have kept me away from mine ! . ............So we'll have to see if I can do something with it this weekend !................I still have not found time to get out the " set-up " disc for our camera so I can get this computer programed for it ,to get some PICTURES posted here already ! ! ............. ..................................................

(in reply to mac49)
       Post #: 77

RE: Gruman Ag-Cat - 12/29/2007 7:36:42 AM   
anothercrashpilot


 

Posts: 124
Joined: 3/30/2007
From: Porterville, CA, USA
Status: offline
quote:

ORIGINAL: D.R.BOWERS

Hi, Mac 49
I just started reading a book on large scale aircraft and I realized that when I asked about balsa construction I hadn’t thought about the stress a big engine will put on a plane. Anyway thank you for the reply to my question. Hope you had a holiday season.


Good flying.
Dale


I'm building mine closer to PLANs and with BIGGER Balsa ! ........And since I hope an 80cc will be big enough , I'm sheeting the Frame sides with 1/16 plywood from one end to the other . hoping to help with frame twist ! ..And then I'll be sheeting the whole Body with 1/16 and 1/8 Balsa ! ................Up front I'm using alot of 1/4 and 3/8 plywood to help tie the engine and landing gear together and into the frame ! ! ! ! ... I'm sheeting the ridged parts of the Tail surface with 1/16 plywood and the moving surfaces with balsa ,But this is adding Alot of Weight ! ! .......................I will also be Sheeting the WINGS ..................................

(in reply to D.R.BOWERS)
       Post #: 78

RE: Gruman Ag-Cat - 12/29/2007 7:40:44 AM   
outacontrol41


 

Posts: 1265
Joined: 11/27/2004
From: Girdletree, MD, USA
Status: offline
quote:

ORIGINAL: mac49

Well, I'm working on a 33% scale based on Floyd Fitzgeralds plans from Model Builder. It is constructed from pine, fir, door skins, and 1/4" plywood underlayment. It is a bit heavy but I plan to attach a large single cylinder gas conversion to it and need the mass to dampen the vibrations. (138cc snowblower, low rpm, big prop.) I'm also using some of the construction methods I borrowed from my EAA magazines. Currently it sits at 14 lb. I'll try to keep it under 45. Landing gear is being manufactured by TNT from 5/16" T6061. A pair of ribbed mountain board wheels will be used. With my work schedule I should be done in 2009. I intended to cover at least as much of it with fabric as Floyd did. Got to save some weight. It will be stand-off scale until I get control of the weight issue.

Mac49.



Looks like the building methods you're using are much different from the original plans....

(in reply to mac49)
       Post #: 79

RE: Gruman Ag-Cat - 12/29/2007 3:01:52 PM   
outacontrol41


 

Posts: 1265
Joined: 11/27/2004
From: Girdletree, MD, USA
Status: offline 		ACP.......Well, sheet! That's a lot of sheeting!!! You may need 100cc.

< Message edited by outacontrol41 -- 12/29/2007 3:03:07 PM >

(in reply to outacontrol41)
       Post #: 80

RE: Gruman Ag-Cat - 12/29/2007 3:12:38 PM   
RedTwilight



Posts: 215
Joined: 1/15/2006
From: Hurdle Mills, NC, USA
Status: offline 		ACP- Why not cover the tail surfaces with fabric like the full scale version? And sheet the rest of it. Still alot of sheeting.

_____________________________

Parkzone P-51, Hangar 9 P-51 PTS
'96 Mustang Cobra 330hp

(in reply to outacontrol41)
       Post #: 81

RE: Gruman Ag-Cat - 12/29/2007 7:17:52 PM   
bofrcr


 

Posts: 132
Joined: 5/8/2004
From: clyde, OH, USA
Status: offline 		Hello Guys! In going through this thread,, it brings to mind a local aplicator that had/has a grumman ag cat. When I was farming,, we'd contract him on a regular basis for appling pesticides and fungicides by air,,when he came out to spray our fields,, it was like having your own private airshow! He knew I was involved with models,and I'd flown a number of times at there airfield,,too Just something for you guys to think about,, all spray planes have the bottom of the spray tank open like a big clamshell,, so in an emergency,, they hit the "panic button",(mounted on the joy stick) and dump the entire load in a fraction of a second! at airshows that was always a favorite thing,, kinda looked like a forest fire plane! (at airshows,, they'd use colored water) and if anybody's interested,, the color of the product sprayed,, would be either yellow,, or light blue As I remember,, it's quite expensive to have your fields sprayed by air,, about $7-8 an acre,, vs $3-4 by ground application anyway,, any of you guys gonna have it spray? oh,,by the way,, the term,, "crop duster" is way out of date,, hasn't been and dry material used in almost 45-50 years ok,, good luck!

(in reply to RedTwilight)
       Post #: 82

RE: Gruman Ag-Cat - 12/30/2007 9:13:19 AM   
anothercrashpilot


 

Posts: 124
Joined: 3/30/2007
From: Porterville, CA, USA
Status: offline 		....I'm sure I'll be RE-THINKING the sheeting/covering as I go ! ? ! ..............Since the Plans were Enlarged and a Bigger engine used , I was more concerned with the strength of the whole thing and wanted to BEEF it up ! ............... And as I mentioned earlier on I wanted to build it like a Tank ,But was afraid it might weigh like one ! ! ............The TAIL group "IS" ridged with just the Bigger balsa sticks ,And I've only got Ply on the Horizontal Stabilizer , And that has probably more than doubled it's weight ! ...........YES, I DO need to get out a SCALE ! ! ......................Even the FUSE is sturdy without any Sheeting ,and I have'nt even finished framing it ! ! ...........ANYHOW, I'm using this as more of a TEST BED to try out Ideas so "IF" I ever get my KIT , I'll be able to DO-IT- UP- RIGHT ! ! ! ! .......................................................BTW ,Worked all day on every thing else around the house so no progress to report .....

(in reply to RedTwilight)
       Post #: 83

RE: Gruman Ag-Cat - 12/30/2007 4:38:17 PM   
mac49


 

Posts: 42
Joined: 6/6/2002
From: BREMERTON, WA, USA
Status: offline 		Outofcontrol41 - I'm using modified light aircraft building techniques that I saw in the EAA books that I have. It calls for using plywood gussets and wood triangle inserts to support the structural joints. I cut my own sticks and decided on using 3/8" pine that I selected at the local home building center. I look for linear grain, 20 or greater rings per inch, and light weight and I check every time in there. You have to look at a lot of two by fours to find one good one. I make a lot of sawdust using my table saw. (I use a 7 1/4" carbide finishing saw blade from a battery operated circular saw.) I'd use a lot more spruce if it was carried locally. The only place I can get it without having to order it by mail is at Edensaw in Port Townsend WA. Great stuff, but $10.50 per board foot. They sell if for masts and spars. The other sticks are proportional to their use; mostly quarter inch. If I was using aviation grade plywood I'd be using material about half as thick and it would still be considerably stronger; budget constraints. I've used his outline and beefed up his structure to come-in-line with my seat of the pants engineering. I'm mostly familiar with Naval Engineering.

mac49

(in reply to outacontrol41)
       Post #: 84

RE: Gruman Ag-Cat - 12/30/2007 8:21:15 PM   
outacontrol41


 

Posts: 1265
Joined: 11/27/2004
From: Girdletree, MD, USA
Status: offline 		MAC49, No matter the engineering, really, as long as the final outlines are true to scale and you keep it light as possible you'll have it licked...and...it looks like you're off to a fine start. Will you be selling this plane or keeping it to add to your fleet permanently? If you're keeping it, then build me one after you're done.

(in reply to mac49)
       Post #: 85

RE: Gruman Ag-Cat - 12/31/2007 5:47:39 AM   
mac49


 

Posts: 42
Joined: 6/6/2002
From: BREMERTON, WA, USA
Status: offline 		Outofconrol41 - This one is going to be a keeper. You never know what might be under the tree some year; DA-150. I'd loan you my plans but they'er drawn out on that four by eight sheet of plywood that I'm building on. I manually draw my plans on 3/4" plywood to the scale I intend to work at as my work surface so I can nail cleats to it. USPS and UPS would only ship it as an oversize package via freight even though it only weighs 55lbs.

I've got a number of others started that can be seen in the background of one of the photos. One that is even closer to completion is a 33% Taylorcraft E-2 that I am building from Paul Matt's scale drawings. I'm also working on a 50% British Nieuport Nighthawk (Joseph Neito), a 33% Fokker DVIII (Air Age WWI Drawings), and others. I get distracted sometimes and go off on a tangent trying some new idea. (Ok, so there is also a Bristol Fighter and a Fairchild FC-1 too. They need to be more thought given to them.)

The Grumman Ag-Cat kinda looks like a Grumman F3F, which is one of my favorite fighters. The retracts make a 33% a bit heavy. (I have this thing about large scale.) I have the five-view drawings for the Boeing Model 95 Mailplane that I'd also like to build in 33%, and the Douglas M-2/4 Mailplane (Paul Matts), and the DH-4-M2 Mailplane (William Wylam), and ..... Building for others would really be hard, I get pretty attached to my creations. I don't even have enough time for myself. I need to retire and build a hanger. Spouse and college aged kids have other ideas though.

mac49

(in reply to outacontrol41)
       Post #: 86

RE: Gruman Ag-Cat - 12/31/2007 7:59:23 AM   
outacontrol41


 

Posts: 1265
Joined: 11/27/2004
From: Girdletree, MD, USA
Status: offline 		Wasn't 100% serious...just wanted to see what you'd say )write(....but I'm also going to build the Agcat, too but according to the original plans. That's really more my size range. I am, however, very impressed with the workload you put on yourself and what you're able to accomplish. I have actually only recently gotten into building but I don't find it that hard to do as long as I've got the plans and I build them to correct scale indended by the designer. I appreciate you taking the time to post your photos of your Agcat project....It's going to look and fly great when you're done.
Have you thought about a spray/dust system for your plane or are you going to wait and see the final weight before you decide?

(in reply to mac49)
       Post #: 87

RE: Gruman Ag-Cat - 1/1/2008 6:55:18 AM   
mac49


 

Posts: 42
Joined: 6/6/2002
From: BREMERTON, WA, USA
Status: offline 		Outofcontrol41 - Weight is going to be an issue. I'm considering a spray rig or water drop. I like the waterdrop the best. I started mocking up one of the wings today and it was coming out a bit heavy. I'm either going to have to get the forstner bits out and start it on a diet or go back and rethink the structure. The built up spar I decided on is the problem. I'd like each finished panel to weigh in around 48 oz or less. I did the same thing on the tail also, made it too robust. I redid the structure and saved about half the weight. That's the nice thing about designing and cutting my own parts. I'm also learning for the next project. The wing really looks neat laying out on the work surface, but that great big spar, it just doesn't look right. It's way to strong. Something in 3/8" or 5/16" with a 1/16" plywood web is really all that is needed. The forstners can eliminate any other excess. I think I'll let my Dremal Router do a little more weight control on the plywood doublers.

Floyd's Ag-Cat is a real nice size; doesn't take a moving van to move it either. There's a lot of engines in the 2 to 3 cubic inch range that would give it scale like performance. When I was a kid back in the 60's and 70's and worked on a dairy in Idaho, I use to watch the crop dusters do their nocturnal dances over the seed fields. (Got to take care of the pollinators.) It would take some pretty good skill to fly an RC plane the way they flew them. A crop duster could really put on a show.

Floyd's plans are pretty reasonable but I think he left some of the decisions up to the builder. I think you'll enjoy it. On the landing gear, I turned mine over to a commercial out fit because I wasn't sure I wanted to tackle bending the 2 inch wide by 5/16 inch thick bar I decided I needed. I didn't think I could get the bends at the correct locations on the opposite sides. I'm hoping they do.

Post a few pictures as you build. I'm sure you'll be out flying while I'm still getting mine together. (I'll be working on the E-2 once in awhile also.)

PS - HAPPY NEW YEAR!

mac49

A quick update: I'm going to go with the lower wings using the 1/2 X 1/2 spar. I'll use only one side with the web. One of the concepts I was going to explore with this model was using as much product from the local home center as possible; see if I can keep the cost of such a large project within reason. I will get the router and forstner bits out and eliminate unnecessary weight. The upper wing pannels will be built using 3/8 X 3/8 spars with door skin web on one side. It may turn out to be a lot closer to 50 than 45 lbs. The DA 150 is less than 10 lbs and near 16 1/2 hp. That will be really tempting down the road.

I checked out my perspective conversion engine again this morning. I believe I'll be using it as the basis for the other cylinders for the dummy radial engine; it looks pretty convencing. May through in a few brass tubes to give it some pushrod character.

The Holiday Season is at an end and I go back to the office tomorrow. It's been years since I've had this length off at home to build. I'll be grabbing time as I can now. I've got a number of lengthy trips coming up. I'll post my progress.

mac49

< Message edited by mac49 -- 1/1/2008 11:17:05 PM >

(in reply to outacontrol41)