Author Topic: Size Plane for a Brodak 40 (Read 4521 times)

phil c · « **on:** September 30, 2006, 07:29:42 AM »

Okay, I need some educated guesses. How big to make the plane.

I found "too big". The last Giles I built had a 64.5 in. span and 780 square inches. It flew just fine on B40, but a bit too slow. Typically 5.8 sec. laps on 60 ft lines, which is only viable in 2 mph breezes. When it is set to run where it likes, in its nice strong 4 cycle, the B40 just can't pull this big a plane fast enough. I'm guessing 650 sq. inches would cut the drag down enough to let it fly 5 sec laps.

RC Storick · « **Reply #1 on:** September 30, 2006, 07:35:55 AM »

Engine size does not regulate the speed of the plane. Prop pitch does. Of coarse you need enough power to pull the weight.

Dick Fowler · « **Reply #2 on:** September 30, 2006, 08:04:20 AM »

WOW Phil... your Brodaks have more punch than mine do! Must be the nitro!

Seriously, mine produces a bit more power than a strong reworked Fox .35. I don't think they have the punch of a .40 LA. I would guess 550 to maybe 600 sq. in. would be in the ballpark.

tom hampshire · « **Reply #3 on:** September 30, 2006, 09:20:37 AM »

Dick - There's a pretty sizable torque difference between the first and second version B40's. The porting changes to the third and fourth production batches make the current version happy on an 11/5, the first version like either an 11/4 or, best. a 10/5. Purchase date doesn't always tell which you have. The best way to tell is to pull the backplate and look for the eyebrow cuts in the piston skirt and sleeve base indicating the current version. The first version does not have them. I'd think the current version should work up to 625 square inches with good authority, the first version up to 600-610 or so. If you want to go bigger, up the tank size so you have enough fuel capacity to add nitro. Best, Tom Hampshire

Gordon Tarbell · « **Reply #4 on:** October 01, 2006, 08:56:51 AM »

Could you show pictures of these eyebrow cuts ? I would like to correctly identify mine.

tom hampshire · « **Reply #5 on:** October 01, 2006, 03:39:04 PM »

Grodon - Photo enclosed, I hope. I made an error when I said the second version sleeve had eyebrow cuts. Only my re-ported prtotype does, when Sergey made the production modifications he opted to simply shorten the sleeve base. No matter, the idea is to feed the bases of the bypass channels more easily. The cuts are the arc shaped recesses in the bottom of the piston, one under each wristpin hole, shown on the piston with a connecting rod in the photo. The piston without a rod is a first version, without the eyebrow cuts. Tom H

Alan Hahn · « **Reply #6 on:** October 01, 2006, 05:31:04 PM »

My B40 does just great on my P40 Arf (listed as 560 sq in).

peabody · « **Reply #7 on:** October 01, 2006, 06:05:44 PM »

I think that more important than wing area is frontal area, or even volume....

Dennis Moritz · « **Reply #8 on:** October 02, 2006, 08:02:03 AM »

Airfoil thickness? Also a factor. Right.

Ron King · « **Reply #9 on:** October 02, 2006, 10:04:59 AM »

My profile Cardinal (thick wing, 589 squares, 47 ounces) and my profile Roadrunner (medium wing, 610 squares, 45 ounces) both fly very well with the Brodak 40. I use 10 percent fuel and run the APC 11.5x4 "CL Stunt" prop.

My engines are a mixed bag of old and new -- and I cannot tell the difference when I'm flying. The engine runs very well.

My .02,

Ron

Steve Fitton · « **Reply #10 on:** October 02, 2006, 10:13:48 AM »

How many head shims are you guys using?? I'm running a block 3 motor with one extra .010 shim. I put the shim in because as the motor ran in it seemed to get harder and harder to needle. It has a slight tendency to flame out without warning as well, if you get it on the rich side...currently the motor resides on a 34 ounce Brodak Mauler with a TF Super M 11x4 prop.

Steve

Ron King · « **Reply #11 on:** October 02, 2006, 12:44:03 PM »

Quote from: Steve Fitton on October 02, 2006, 10:13:48 AM

How many head shims are you guys using?? I'm running a block 3 motor with one extra .010 shim. I put the shim in because as the motor ran in it seemed to get harder and harder to needle. It has a slight tendency to flame out without warning as well, if you get it on the rich side...currently the motor resides on a 34 ounce Brodak Mauler with a TF Super M 11x4 prop.

Steve

Steve,

I typically swap the Brodak gasket (.008) for an OS gasket (.016) and run 10 percent fuel. Your added .010 shim to the stock Brodak gasket is right in that same ballpark.

One of my engines had the same flame out tendency. I switched my usual Sig RC plug to an OS #8 glow plug and things are working better. The OS plug is used in our RC helicopters and we run them very rich.

Ron

phil c · « **Reply #12 on:** October 02, 2006, 03:06:13 PM »

Robert, the prop pitch only controls airspeed when the motor has excess power. If the motor is producing all the power it can, changing the prop pitch doesn't change the speed. I've tried.

thanks for the other ideas. I think I will go with 600 squares and 60 inches. I'm putting together a next gen plane for adventuresome sport flyers. I don't want to make it too touchy.

As far as frontal area, it really doesn't matter. I've done extensive testing. What matters is the total surface area of the plane. Wing thickness, airfoil shape, wing shape, etc. only contribute drag down in the 1-2% range. Every square inch, whether it's fuse, wing, or tail, contributes directly to drag and slows the plane down. I'm going to keep a nice, thick wing for strength and lift.

john e. holliday · « **Reply #13 on:** October 03, 2006, 08:44:14 AM »

Phil, I had my B-40 in the Brodak Olympic originally and was more than enough power point prop 11-4 with 10% Sig fuel and Fox Idle Bar plug. It is now in rebuilt/recovered Brodak Oriental. It has more than enough power, but, had to install a bigger fuel tank in order to get the run I like. And to the Brodak Mauler I have, it is flying the pattern with the new Brodak 25. I think it is a much better handling engine than the 40. Both great engines in my opinion. DOC Holliday

Steve Helmick · « **Reply #14 on:** November 14, 2006, 11:04:12 PM »

Quote from: tom hampshire on October 01, 2006, 03:39:04 PM

Grodon - Photo enclosed, I hope. I made an error when I said the second version sleeve had eyebrow cuts. Only my re-ported prtotype does, when Sergey made the production modifications he opted to simply shorten the sleeve base. No matter, the idea is to feed the bases of the bypass channels more easily. The cuts are the arc shaped recesses in the bottom of the piston, one under each wristpin hole, shown on the piston with a connecting rod in the photo. The piston without a rod is a first version, without the eyebrow cuts. Tom H

Is this the entire difference...piston notches, sleeve trimming and muffler outlet? How much should I cut off the bottom of the sleeve? Could you give dimensions for the notches in the piston? I'm a machinist and old speed flier, so I can do this just fine.

The one I have is from the first batch, NIB. I'd like to do any rework before I run it. It had the liner rotated a bit from aligning with the exhaust stack, as many of the first batch did...fixed that.

I've seen John Miller's B.40 powered Pathfinder fly...I was impressed with the engine. OTOH, I reckon it will probably be ok for an Oriental, as it is. What would you suggest?

Steve

tom hampshire · « **Reply #15 on:** November 15, 2006, 05:06:52 PM »

Steve - Hope my late reply gets to you in time. The sleeve timing was changed from 146/132 in the first version to 138/124 in the second version. IFFF you want to tackle this, feel free, but it involves a sleeve drop, either by turning the underside of the top flange down to lower the sleeve, or making a mounting fixture to hold the crankcase, mounting it in your 4 jaw, indicating it and then turning the top of the block down. Unless you really want to play with machine tools, its easier to simply buy a new p/c set. As to the bypass channels, you can cut the eyebrow reliefs in both the piston and sleeve by eye, and come out just fine.

One thing I'd suggest is that if you grind or mill sleeves for any reason, deburr the edges (and plating) with great care. If you do enough of them, sooner or later you'll miss a burr and scar the piston. The trick is to insert the piston rod first, from the bottom of the sleeve, so its upside down on the first trial fit. If you goof and scar it, you have now created an oil control channel on the bottom of the skirt, not ruined the assembly by scratching the compression band.

tom hampshire · « **Reply #16 on:** November 15, 2006, 05:11:19 PM »

Steve - the previous post was me. I somehow hit a send key before I got my name in. Are you real sure I qualify as a machinist? Tom Hampshire

Steve Helmick · « **Reply #17 on:** November 17, 2006, 11:39:34 PM »

Thanks for your information and advice. This project sounds like a lot more fun than the stainless steel parts I've been working on for the last week. The splinters are miserable in the fingers. I've printed out your post and will put it with the engine for use in the near future.

Steve

tom hampshire · « **Reply #18 on:** November 21, 2006, 12:35:46 PM »

Steve - One other thing... It's also better to change to a new p/c set because the sleeve taper was reduced to one thou from 60 microns, or about 2.25 thou. The lesser sleeve taper works better in a 2-4 run setup, as the temperature is much lower.

BTW, I think you are the guy who tipped us to roll taps in a previous post. Thank you! Tom H

Steve Helmick · « **Reply #19 on:** November 22, 2006, 10:39:50 PM »

Tom...you're welcome to the tip on roll taps! I had to tap a bunch of stainless parts today...blind holes. One roll tap did dozens and dozens of holes, and was still working like new. Still, some guys don't like 'em, and there are places where you don't want to use them. I use roll taps every time I possibly can, because they make a good snug thread, don't break, and I don't have to pick the chips out of the hole. You have a "PM".

Steve

Bill Hummel · « **Reply #20 on:** November 23, 2006, 07:35:20 PM »

Tom, Doc Holliday had it correct that the B.25 is an AWESOME engine! You guys really got this one "dead on". Absolutely friendly, nice power, super 4/2/4 run, very tolerant of props/plugs/fuel. Great work! Looking for the new B.40's to be along the same lines. Thanks for your efforts!

phil c · « **Reply #21 on:** November 23, 2006, 08:20:51 PM »

I started using thread rolling taps for aluminum motor mounts. It is the only way to go. Just make sure you experiment a bit with the pilot hole size and using some lube. Depending on how many holes you have to tap and how fast you want to go, the pilot hole can be pretty critical. I ended up drilling several pilot holes and working down in size to find the best combo to give a good thread with minimum torque. A couple thous oversize sure works easier than a couple under.

peabody · « **Reply #22 on:** November 24, 2006, 06:19:45 AM »

Phil...what size pilot for a 4-40?
Thanks

phil c · « **Reply #23 on:** November 24, 2006, 09:34:59 AM »

I've been using 0.098 for a 4-40. The 4-40 od is about .11. You really have to do some experimenting. different brands of taps will cut a little differently. The metal can make a difference. And esp. what you use for a lube and how fast you tap make a big difference. My lathe will go down to 112 rpm, and with the right combo of hole diameter and lube it will tap holes all day.

Steve Helmick · « **Reply #24 on:** December 05, 2006, 11:10:51 PM »

I use the chart, and aim for a 65% to 75% thread. I'll try and remember to print a copy of the chart and scan and post it for small sizes. I ALWAYS double drill or drill and ream the tap hole. By double drilling, with good lube and sharp drill, it'll be within +/- .001" of nominal. I use "stubby" Screw Machine drills as much as possible. Jobber length drills will make bigger holes. You also need to countersink the hole a bit more than normal for a roll tap, because it'll pull up a burr. Removing it after tapping isn't as good as doing it prior to. Old fashioned STP Oil Treatment will work pretty good for lube on roll taps, in about any material.

Steve

Edit: I added the scans, but couldn't read them, so deleted them. I can read the .jpg's, but not after posting them here. Not sure why. FWIW, I'd use a #39 drill for the 4-40 (as recommended), #33 for the 5-40, and .125" for a 6-32. To repeat: These are for Roll (Form) Taps, not conventional taps.

Paul Smith · « **Reply #25 on:** December 13, 2006, 04:37:15 AM »

How about a picture and source for these taps?

Paul Smith · « **Reply #26 on:** December 13, 2006, 04:45:21 AM »

Quote from: Steve Fitton on October 02, 2006, 10:13:48 AM

How many head shims are you guys using?? I'm running a block 3 motor with one extra .010 shim. I put the shim in because as the motor ran in it seemed to get harder and harder to needle. It has a slight tendency to flame out without warning as well, if you get it on the rich side...currently the motor resides on a 34 ounce Brodak Mauler with a TF Super M 11x4 prop.

Steve

I own just one Brodak 40. This is the first I've heard of "four versions". Haven't a clue which one it is.

At first, I thought I had a real winner. But now, it refuses to come up to a good RPM on a 10/6, doesn't needle well, and has the power of an average Fox 35 Stunt. I even went so far as to replace the heavy muffler with a tongue.

I bought this under the impression that it was a ready-to-use stunt engine, not a piece of raw material that needs work. I don't mind fiddling around with old combat engines and junk from ebay, but new stunt engine used for stunt should be ready to use.

As for airplane size, I go with something of the Flite Streak size, certainly not a ral stunter.

bruce malm · « **Reply #27 on:** December 13, 2006, 11:12:03 AM »

Have you been running the Tongue muffler all the time. I ran into the problem on a B40, and I have about 10 of them, that was giving me a lot of problems. I break them all in with about 20 2+ runs. This particular engine wouldn't needle and hold a setting with the tongue muffler(note: It ran fine during break in). After changing tanks, plugs, props, fuels, I still couldn't make it happy. I finally put the stock muffler on and it runs great and holds a needle setting. I talked to a lot of people and they clarified that some of the B40S need a lot more running to get fully broken in., 1>3 hrs.

This one was just overheating. When I get more time on it, I'll re-install the tongue muffler and increase the hole sizes or add holes to relieve any back pressure.
As Randy Smith has pointed out to me, the tongue mufflers are made to fit various engines and it is standard procedure to enlarge the holes or plug them off according to the aircraft its on. Weight, wing area, prop size, fuel etc.
Currently I use powermaster 10/22 and Fireball hot plugsand various props, 10-5>11-4, and will be trying some 3 blades.

Hope this helps and have a Merry Christmas.

Bruce

Paul Smith · « **Reply #28 on:** December 13, 2006, 01:31:25 PM »

Quote from: bruce malm on December 13, 2006, 11:12:03 AM

Have you been running the Tongue muffler all the time. I ran into the problem on a B40, and I have about 10 of them, that was giving me a lot of problems. I break them all in with about 20 2+ runs. This particular engine wouldn't needle and hold a setting with the tongue muffler(note: It ran fine during break in). After changing tanks, plugs, props, fuels, I still couldn't make it happy. I finally put the stock muffler on and it runs great and holds a needle setting. I talked to a lot of people and they clarified that some of the B40S need a lot more running to get fully broken in., 1>3 hrs.

This one was just overheating. When I get more time on it, I'll re-install the tongue muffler and increase the hole sizes or add holes to relieve any back pressure.
As Randy Smith has pointed out to me, the tongue mufflers are made to fit various engines and it is standard procedure to enlarge the holes or plug them off according to the aircraft its on. Weight, wing area, prop size, fuel etc.
Currently I use powermaster 10/22 and Fireball hot plugsand various props, 10-5>11-4, and will be trying some 3 blades.

Hope this helps and have a Merry Christmas.

Bruce

Are you saying the tongue muffler has too much or too little back pressure?

Or maybe just not right for the Brodak?

It seemed OK with no muffler at all.......

I've bought several tongues form the three usual suspects. All had way too many holes and almost no back pressure.

I'll continue to use the B40 as a sport engine.
Maybe it'll grow up to be a stunter some day.

I flew a G21/40 today,,,, 43 degrees and 19 MPH breeze,,, on nice Michigan day. Now that's a Stunt 40!.

bruce malm · « **Reply #29 on:** December 13, 2006, 05:33:23 PM »

Too much back pressure The engine pulls more of a load in the air. All mine ran perfectly during break-in using a 9x6. I didn't run into the problem until on the airplane, turning a 10x6 on GMA 10/22. After fooling around with all the other items, I put the stock muffler on it and it ran perfect. U-can test it on the ground doing the normal nose up to back to level test. As soon as I put the stock muffler on it would do a nice 2-4-2. Put the tongue muffler back on and wouldn't. Some of the B40's are tighter than others and will just take more run time to fully break in. I also have all 3 styles of tongue mufflers and they all acted pretty similar. I was educated that it was normal to adjust the hole size to , prop,engine, etc and In trying to find the problem I had opened up some holes and it would run very slightly better. Later when I flew with the stock muffler I didn't have the problem so I will run it until I get more time on it and then switch to the tongue muffler. I will always take a stock muffler with me so if I run into a problem on newer engines as its so easy to change, just as another trouble shooting item.
Hope this helps, it's just my experience with this particular B40.

PS you might try running a 9x6 on it and see how it acts. If it runs a smoother and needles better, it probably just needs more run-in time.
Bruce

Author Topic: Size Plane for a Brodak 40 (Read 4521 times)

Alan Hahn