Author Topic: Perky speed (Read 15601 times)

bob whitney · « **on:** July 10, 2016, 10:15:02 PM »

i am running a .250 venturi with a pee tube on my nelson 15 , how big can i go and still get off the ground??

Paul Smith · « **Reply #1 on:** July 10, 2016, 10:32:53 PM »

What's a pee tube? Like a 1/2 spray bar?

Motorman · « **Reply #2 on:** July 11, 2016, 08:41:42 AM »

You'll have to bite the bullet and make .260, .270, .280 ect. Bob, just make a .275" I don't think you'll get more than that. My question is can you make up time at top end with a venturi that coughs the first lap.

MM

Paul Smith · « **Reply #3 on:** July 11, 2016, 09:10:20 AM »

At the moment Bob is the Top Dog at 114 MPH. I guess .250 with a pee tube worked OK for him.

Maybe the thing to do is tach runs on the ground to find max RPM, then see if it will get off the ground.

If you could go 120 MPH true airspeed, you could afford a 1-second acceleration and still average 116 MPH.

Jim Carter · « **Reply #4 on:** July 11, 2016, 09:46:34 AM »

I'm not shur' but you could lemme' have it and I'll see what I can do!! Granted I know nuttin' 'bout machine work but I do a purty' durn good job 'wit concrete!!

Motorman · « **Reply #5 on:** July 11, 2016, 10:54:46 AM »

I can fix that.

bob whitney · « **Reply #6 on:** July 11, 2016, 12:25:56 PM »

a pee tube is the tube that sticks into the center of the venturi instead of using the TD type venturi

if i have time i might make a .275 venturi and make a couple of smaller inserts to bring it back down without having to take the plane apart if need be

Motorman · « **Reply #7 on:** July 11, 2016, 02:20:14 PM »

I'm assuming the dump tube is 1/16th tubing. If you're going to make inserts I'd make the initial hole big so the inserts have some wall thickness and a notch to go over the dump tube to keep it in the choke for the Bernoulli effect. If you're using an early Nelson NVA (KKtype) you might want to check the diameter of the discharge hole and open it up for better fuel signal. Alignment of that hole with the dump tube is critical. As you go bigger on the venturi you come to a point where you have to open the NV to get it off the ground then it runs rich at top end.

MM

Jim Carter · « **Reply #8 on:** July 11, 2016, 06:35:50 PM »

Quote from: Motorman on July 11, 2016, 10:54:46 AM

I can fix that.

I actually sent it back to Fox a couple of years before they shut down and received a replacement for 50%. I had no problem accepting that deal. I believe Ms. Sharon commented something about they didn't have enough JB WELD ..... !

Paul Smith · « **Reply #9 on:** July 12, 2016, 06:48:50 AM »

The Fox 50% exchange amounted to selling direct at the usual wholesale price. For a while they would accept any broken engine in exchange.

Ken Burdick · « **Reply #10 on:** July 12, 2016, 09:29:31 AM »

wait....you've forgotten the disclaimer. "Plier marks"

Paul Smith · « **Reply #11 on:** July 12, 2016, 10:50:34 AM »

The plier marks referred to FREE warranty work.

Back then, a Fox 35 Stunt was a rich kid's upgrade from a McCoy. One engine for the price of three. And well worth it, considering Duke's quality control in the early 60's.

C.T. Schaefer · « **Reply #12 on:** July 12, 2016, 04:35:09 PM »

Due to the elevated speeds that are being attained this season in Perky, I am currently working on an NOS installation to boost up my Mk2 Rossi. Should be ready for next seasons air wars! TS

Paul Smith · « **Reply #13 on:** July 13, 2016, 07:13:10 AM »

The Schaefer Perky has always been the fastest perky Perky, as opposed to Perky-like all out speed planes with upside engines and space age materials.

bob whitney · « **Reply #14 on:** July 13, 2016, 08:49:43 AM »

until now

Ken Burdick · « **Reply #15 on:** July 22, 2016, 03:45:15 PM »

F2C rad racer does it again.......good on ya Bob. Perky is yours.(amongst other events)

Motorman · « **Reply #16 on:** August 14, 2016, 08:20:52 AM »

Ok, scrap box special coming up. What do you use for the crutch? I've got spruce, bass or hard balsa.

Should I try to build it light or, do these things tend to come out nose heavy?

How many rpm can a plastic spinner turn before it explodes?

MM

C.T. Schaefer · « **Reply #17 on:** August 14, 2016, 06:48:45 PM »

The kit is all balsa except for mounts and firewall. Dream up a better gear. Do a better elevator. Wire joiner? Might be a bit nose heavy with Nelson. Mine is 16oz with R Mk2 and Fox spinner. I would not trust plastic spinner at the 33,000 rpm that I wish my Rossi turned.

Motorman · « **Reply #18 on:** August 14, 2016, 10:36:36 PM »

I have a Rossi Mk2 abc with stock crank but it's dieselized with a nelson head. Sweet little motor. I guess I could convert it back to glow. Hard to find rear bearings for those.

That balsa block the wing sits in, how much do you hollow it out about 3/16" wall thickness?

Does your push rod come off the top or bottom of the wing?

Thanks,
MM

C.T. Schaefer · « **Reply #19 on:** August 15, 2016, 06:42:00 AM »

Leave a little meat under wing. I think pushrod is on the bottom. I have external lead outs. I built the Perky in order to use the Rossi which had not been out of the box for almost 30 years. It has really been a great motor but I think it is mostly tapped out. Hopefully over the winter a new project will take shape.

Paul Smith · « **Reply #20 on:** August 15, 2016, 07:18:57 AM »

Here's my deal:

I made a wood bottom like a speed pan and hold it together with 3 bolts. It's been working for eleven years now. The take-apart is handy for engine & tank changes.

I put the leadout outdoors under the wing. That way I can move them, too. It's not worth the trouble to hide 8" of wire.

My top has full length spruce sides, 1/8" x 1/2" sanded to the contour.

Motorman · « **Reply #21 on:** August 15, 2016, 09:44:50 AM »

Paul did your tether point end up ahead of the wing tip?

Thanks,
MM

Paul Smith · « **Reply #22 on:** August 15, 2016, 05:06:14 PM »

Yes.

I have several holes in a plywood plate and eventually worked up to the most forward. I think any leadouts within the wing are too far aft.

That's not a magnesium pan. Just painted wood.

Motorman · « **Reply #23 on:** August 15, 2016, 05:56:39 PM »

Were both lines in the front hole?

Does the landing gear have to be as long as the plans for the rules?

What is driving the back plate of your spinner?

Thanks,
MM

john e. holliday · « **Reply #24 on:** August 15, 2016, 08:21:09 PM »

What do the rules say?

Motorman · « **Reply #25 on:** August 15, 2016, 10:32:18 PM »

Model must be equipped with two wheels of 1 3/8” to 1 ½” Diameter.

MM

C.T. Schaefer · « **Reply #26 on:** August 16, 2016, 07:00:30 AM »

PS Don't forget tip weight. An ounce is not too much.

Motorman · « **Reply #27 on:** August 17, 2016, 12:29:53 PM »

What bellcranks are you guys using. Will a 2" Fox fit?

MM

Paul Smith · « **Reply #28 on:** August 17, 2016, 01:04:01 PM »

I use an old Fox 2" bellcrank. The lines go through two different holes. In my opinion, going from 2" to the same hole 8" away is too much stress.

The top & bottom assembly bolt is also the bellcrank bolt.

I use the Tru-Turn spinner system. Expensive, but solid.

Motorman · « **Reply #29 on:** August 17, 2016, 03:37:19 PM »

Tommy, just sunk in a tip weight, 30 grams before epoxy.

MM

Motorman · « **Reply #30 on:** August 27, 2016, 01:41:16 PM »

How much does a Perky weigh?

MM

Dan McEntee · « **Reply #31 on:** August 27, 2016, 04:14:11 PM »

Quote from: Motorman on August 27, 2016, 01:41:16 PM

How much does a Perky weigh?

MM

I'm not exactly certain, but I would hazard a guess that it would be what ever it says on your scale?
Type at you later,
Dan McEntee

C.T. Schaefer · « **Reply #32 on:** August 28, 2016, 07:09:46 AM »

Mine is a pound. Vigani's probably about the same with the Fora.

Jim Carter · « **Reply #33 on:** August 28, 2016, 08:32:53 AM »

My 01 plane with the OS .15 with muffler weighs in at 15.0 ounces while the 02 plane with a Fox .15 weighs in at 13.5 ounces with the Tatone muffler.

Paul Smith · « **Reply #34 on:** August 28, 2016, 12:47:18 PM »

Those are good weights for planes with light weight sport engines.

But the speed engines are 2-3 ounces heavier and require both tail weight and stronger structure. I think 16 to 18 ounces is realistic for a power Perky.

Carl Cisneros · « **Reply #35 on:** August 28, 2016, 06:32:17 PM »

What are some good props to use on the perky's?

Plan on using either a Cox Conquest 15 Racing, Rossi Mk1 RR 15 or Nova Rossi`15 RE motor in mine
when I build it this winter,
I will be making mine like Paul did his.

Carl

Motorman · « **Reply #36 on:** August 28, 2016, 08:22:18 PM »

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LX1687&P=7

MM

Carl Cisneros · « **Reply #37 on:** August 28, 2016, 08:53:27 PM »

thanks MM

Motorman · « **Reply #38 on:** August 29, 2016, 06:32:45 PM »

Progress has been made. Bellcrank is a Fox 2" cut down to 1-1/4" with buttons installed. That should cut the angle down on the rear lead out.

The spinner is from China and sold as the 1.5" miracle spinner on eBay, same weight as the true turn and not as pointy.

They also sell a carbon fiber spinner that's 1.750". I was thinking of cutting it down to 1-1/2" and making a magnesium back plate, how light would that be yo.

MM

Carl Cisneros · « **Reply #39 on:** September 04, 2016, 05:39:39 PM »

MM
is your wing a solid wing or did yousheet the kitted wing?

Also, what sizetank do I need to make for the plane?

Carl

bob whitney · « **Reply #40 on:** September 04, 2016, 07:31:51 PM »

My tanks are 1oz. my nelson gets about 25 laps. the rossi mk 2 runs for ever so I just short tank it

Motorman · « **Reply #41 on:** September 04, 2016, 11:07:34 PM »

Wing is 1/2" solid medium balsa. I wouldn't go any smaller than 25cc for the tank. Which Cox Conquest do you have?

MM

Paul Smith · « **Reply #42 on:** September 05, 2016, 07:15:22 AM »

Quote from: Carl Cisneros on August 28, 2016, 06:32:17 PM

What are some good props to use on the perky's?

Plan on using either a Cox Conquest 15 Racing, Rossi Mk1 RR 15 or Nova Rossi`15 RE motor in mine
when I build it this winter,
I will be making mine like Paul did his.

Carl

I'm not the fastest, but I believe in 4" pitch. 3" won't make the top speed and 5" under-revs the engine.

Starting with 6.6" diameter, I cut the prop until the RPM comes up to my target. The props look small but RPM is king.

Carl Cisneros · « **Reply #43 on:** September 05, 2016, 05:44:54 PM »

Thanks guys

I have a couple of the Cox ABC models. Both have the good rods a buddy of mine in So, Cal made up for me quite a while back.