PointMagu

My Feedback: (11)

I have this insane desire to abuse myself by building the barrel-bodied Grumman GulfhawkII, built for Al Williams.

Since the retracts are almost identical to the F4F Wildcat, perhaps someone has plans, drawings or ideas on fabricating the gear for this aircraft?

Thanks!
Don

All Day Dan

My Feedback: (5)

Don, Robart has s set for that plane. They are for a large size model and I don't know the scale. I was also too embarrassed to ask how much. Dan.

KD5DW

Model Airplane News has plans for the gear.
KD5DW

Dsegal

There is a construction article for fully detailed, retractable landing gear of the F4F Wildcat in the July, 2009 issue of Flying Models. The plan is number CD373. The construction article for the plane is in the August issue. That model has a 56" wingspan. The landing gear is an amazing piece of work.

colvinro

Hi Don, whatever you do; do not buy the Bob Karlsson Wildcat Plans from M.A.N.. I bought a set of these plans and the plans for the airplane and the landing gear plans SUCK! I am a Tool Maker and a Mechanical Designer and I assure you that it is nearly impossible to build a set of landing gears from these plans. The plans are poorly drawn, not drawn to scale and there are many missing dimensions. I have spent many hours trying to make sense of them and I have not had any luck. I have all the machines, welding and CAD tools I could ever need to make these landing gears and I would order them from one of the excellent companies that offer them first; before I invested the amount of time it would take to build them my self, from the Karlsson plans.

Rick

dragonbuilder

My Feedback: (1)

Does anyone know of plans for this plane?

Avaiojet

The Wildcat gear and the F3F-1 gear are different. To use Wildcat gear in a F3F-1 would ruin the look of the model.

I too have wanted to build a great Gulfhawk. I haven't, because there's no gear available.

I do have and drew myself, builders plans and parts drawn for a 72" model. I believe it's 1/5 scale?

I also have started building gear parts for a smaller model at 52". This would be the Pilot kit. I expect to have the gear parts cast.

I did inquire on RCU if anyone was interested in these parst. No interest.

larrymc1

All,
Comet models produced a kit of the Grumman Gulfhawk in 1937. I beleve that the W/S was 28.5". The plans are available for download at RCGroups, Vintage&Oldtimer plans, post#706. The plans are very detailed and all the print wood sheets are in the index. I have printed these out at 125% to give me a model of 35.625"W/S and am in the process of building this model. I have another Gulfhawk that I have built out of DOW foam that has functunal landing gear in it. The Comet plans show the L/G in detail but the measurements are all wrong if you want them to retract. If you are interested I can supply the measurements. My gear is built of brass tubing and sheet and weighs in at 3 oz. I use gears from Servo City to actulate the legs with a HS75BB 180 degree servo for drive. I have cycled them hundreds of time and have no failures.

NavyE6FE

I have the F3F on my to build list some day. Someone that might be able to fabricate the gear is, Sierra gear. There are a few people on another forum that have him build gear for custom giants. I don't know what his requirements are(pictures or drawings) to build a set of gear. I have many pictures of the gear and plane from the NMNA in Pensacola if anyone is interested.

Steve

Avaiojet

Larry,

I'd be interested in the operation of your gear. You must have spent plenty of time in the process of making them.

Photos?

cocobear

My Feedback: (2)

There has been about 6 sets made.This was our first. I am still flying number 2 after a year and a half. No failures.It is driven with plywood pulleys and fishing line instead of sprokets and chains.

http://www.rcgroups.com/forums/showt...&highlight=f3f

larrymc1

Avaiojet,
The operation of the gear is much like the real thing. Grumman used chain, sprocketts and a crank, I am using gears and a servo to the same effect. You have to figure out how much rotation in degrees you need to move and find the right ratio to work. I use a 5 gear set up on both of my units because it works for me. The latest set that I am still working on needed to move 140deg but I could only use a 30 tooth gear because of placement near the side of the fuse 360/30=12deg of movement per tooth. to get to 140' I would have to drive it 11.6 teeth. The servo is a HS75BB and turns 180deg so I will have to install a 24T gear on the servo to drive the 30T gears the required amount. It works out to 12T x 12deg =144deg of movement. It sounds complicated but really isent. The other 2 gears are used as spacers as they are only transfering the movement and keep the legs in time with each other. The hard part is getting the correct leingth of the gear legs and what you are going to use for hinges. I will try to get some pictures this weekend to post.

larrymc1

cocobear,
I am a great fan on what has been done with the molded depron F3F's and have followed the build and watched them fly in the videos. I would have purchased one of these if they had been offered to the public and saved myself a lot of work. The gears that I have been building will need to support upwards of 36oz as that what my best guess is for all up weight. The cowel for the 125% comet design is 5" and I will be swinging a 11" 3 bladed prop (picth to be determined) by an E-Flight 480. I am not the worlds greatest flier so they must be robust enough to handle rough landings when (not if) they happen.

Avaiojet

Larry,

Thanks for that info, I'm looking forward to seeing your work in photos.

Yes, gears do sound complicated, at least to me, but you seem to have it down pat. I'll probably be asking more questions.

Thanks again,

larrymc1

Here are a few pictures of my foam Gulfhawk W/operating landing gear. I havent loaded pictures yet I hope it works.

larrymc1

OK now that I know what to look for here are shots of the gear for the 1937 Comet Gulfhawk.

larrymc1

More pic's can only load 2 at a time files are large.

larrymc1

More pic's

larrymc1

I thought that I would share some pic's of the fuse also, here is the left side.

larrymc1

Right side with wing root being fitted. The left side has only the wheel cut out for now.

ps2727

Now that is some nice work! Simple and light.
Bravo!
Paul

cocobear

My Feedback: (2)

Very cool. Did you put a spring"shock" in the lower strut? If not, I highly recomend it. It will make your gear much more durable!

DJ

Avaiojet

Thanks for those photos. I appreciate your interest AND taking the time to really place some excelent photos of your great work!!

I'll be looking forward to seeing the completed gear installed in your model.

What is the span of that model AND the tire size?

Thanks again!!

LesUyeda

I like the construction:-))))))))

Les

CoosBayLumber

My Feedback: (1)

On the Gulfhawk, they used F2F wings and the fuselage from a F3F as I remember.


Wm.