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Engine basics => Engine set up tips => Topic started by: Paul Taylor on January 04, 2011, 01:32:00 PM
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Subject says it all.
If you had your choice.
List pros and cons...
I hear it take more fuel to break in a Brodak engine?
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LA .46 gets my vote...easy break in...one flip starts every time....plenty of power...and I like the blue color !
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Paul,
If I had a CEO--> mw~ who told me I could only buy one more engine in this lifetime, it would be an LA46. That said, it's worth noting that the Brodak 40 weighs about the same as an OS20FP, and the LA46 weighs almost 40% more (all weights w/o muffler). Not a huge deal for flapped planes, but for flapless planes where weight makes a larger difference, it's worth considering. I have a Primary Force that is borderline overweight at 40 oz and flies nicely with lotsa power using a Brodak 40 (later more powerful version), but would be overweight with an LA46 and the chunk of tailweight which would be required to balance it. So it's a bit of an apples/oranges question IMO. I find both engines very friendly and adaptable. What plane do you have in mind? Or would you choose the plane to suit the engine?
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Heck, buy one of each. The mounting holes have identical spacing and cases are close in length. Both are comparable in price and great stunt engines. I'm inclined to go with the Brodak, but that's just me. I use both interchangeable on my Brodak P-51 profile...as well as 40 fp's and OS 35s'. 8)
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Maybe in a Vector?
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The 46 LA has more beans
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Maybe in a Vector?
I would go with the LA46 and do the popular trick of switching to the LA25 venturi and adding a couple of head shims. Front NVA.
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Subject says it all.
If you had your choice.
List pros and cons...
I hear it take more fuel to break in a Brodak engine?
Simply would depend on which plane it was going to be used in. From memory, when I weighted them, the B .40 was lighter.
Definitely would use EITHER over the .40LA.
Big Bear
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I'm into LA46s. Can be run sloppy sloppy rich in a Vector. I've done it. Engine is very controllable when run this way. Just a hair of a break where useful. Room for a 5 and a half ounce Brodak tank, if you slit F1 (or is it F2). You will need near this much fuel for the pattern when run this rich. LA46s are flexible. Can be run harder using less fuel. There's a recent thread discussing different run styles for LA46s. Take a look, if you decide to use this engine.
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....Room for a 5 and a half ounce Brodak tank, if you slit F1 (or is it F2). You will need near this much fuel for the pattern when run this rich....
Not with the smaller venturi, and you will still have tons of power as well as saving $ on fuel.
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I may be barking up the wrong tree here but I have concerns about the practice of adding head shims—especially OS shims.
I believe that ignition in our engines is a function of compression and the position of the glow plug.
If you look at the 0.724" stroke of the FP 35/40 and LA 40/46, 10° of crank rotation from TDC produces a stroke of only 0.0055". I think that means than adding head shims—especially the 0.016" OS factory pieces when just one at TDC has the effect of 17° of crank rotation—moves the glow plug away a substantial distance from TDC. I don't know what this does to the ignition timing but I suspect that it would reduce power substantially.
Any thoughts from the engine people?
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I would go with the LA46 and do the popular trick of switching to the LA25 venturi and adding a couple of head shims. Front NVA.
Well, there you have it. Same old "screw around with it until it finally works" story with the OS. Or "buy-N-fly" with the Brodak.
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Well, there you have it. Same old "screw around with it until it finally works" story with the OS. Or "buy-N-fly" with the Brodak.
LL~ LL~ LL~
Actually, the only thing I have ever heard that was "bad" about the OS .46 right out of the box, is the possibility of back plate leaks.
Or am I missing something?
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I am hooked on the Brodak .40.....if for no other reason than I like the 2-4 break...so call it a nostagia thing
but also it is ready out of the box...no back plate changes or needle changes. Both engines require a proper
break-in time to run their best. When properly broken in both engines start easily hot or cold.
Should anybody want to get rid or their Brodak engines I will gladly trade my remaining LA .25's and .46's.
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I am hooked on the Brodak .40.....if for no other reason than I like the 2-4 break...so call it a nostagia thing
but also it is ready out of the box...no back plate changes or needle changes. Both engines require a proper
break-in time to run their best. When properly broken in both engines start easily hot or cold.
Should anybody want to get rid or their Brodak engines I will gladly trade my remaining LA .25's and .46's.
HI David,
The B-.40 runs great. Ours are no problem! I like a 4-2 run myself. ;D I was just "shocked" by Clint's post. LL~
Big Bear
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LL~ LL~ LL~
Actually, the only thing I have ever heard that was "bad" about the OS .46 right out of the box, is the possibility of back plate leaks.
Or am I missing something?
Your missing , many feel the rear mount NVA is not as good as front mounted. I also see the motor is better when you get a NEW NVA and set it up inside the venturie.
Randy
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Your missing , many feel the rear mount NVA is not as good as front mounted. I also see the motor is better when you get a NEW NVA and set it up inside the venturie.
Randy
My bad, Randy! From the beginning I never considered running the "remote" NVA.
I do remember some rather poor reviews of the early Brodak .40s, which hasn't been mentioned due to an attempt at "politeness". If I am doing a "serious plane" that would use probably either of the 2 engines mentioned (a classic .35-.40 size airframe), it gets an Aero Tiger .36. Of course, "me" and "doing a serious plane", some would find "odd". ;D
Bill
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My experience with the early Brodak 40s wasn't bad, just not as much hosspower as the later versions. Considering the very light weight of the engine, the power/weight ratio of the earlys wasn't bad, just modest. I had an early on a 460 sq in somewhat porky 38 oz All Australian OTSer, and had very good, very predictable results with it.
I'm curious if it's possible to buy a later version p/l to drop in to an early case. Or maybe the crank timing is different too(?). Tom Hampshire, are you reading this thread?
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HI David,
The B-.40 runs great. Ours are no problem! I like a 4-2 run myself. ;D I was just "shocked" by Clint's post. LL~
Big Bear
Sorry 'bout that, Bill. I was just having flashbacks of the old OS FP days! LL~
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Ran both engines. Each one of them is targeted to different airframe sizes/weights. B40 fits in a niche where full-on stunt motors don't venture while LA46 tries to play in the domain of the "big boys". Both PA and RoJett lines of stunt engines, start with .40 size stunt motors that produce a LOT of power and are orders of magnitude better stunt engines.
LA46 is heavy, needs a lot of changes to make it work(venturis, shims, replace cracked plastic backplates with metal ones). No amount of tweaking can change the fact that LA46 is NOT timed for stunt.
B40 on the other hand is light(fox35 light), needs no mods or shims, just proper break-in. It's timed for stunt(4-2-4 style) and enough power to pull any model under 48oz with authority. It will not run in constant two cycle so don't try.
In summary, I think B40 works very well in the model weight/size range it was designed for while LA46 requires a lot of work and cannot compete with stunt engines in the same model weight/size range.
Steve
P.S. When picking a motor, make sure to take into account local motor expertise.
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Sorry 'bout that, Bill. I was just having flashbacks of the old OS FP days! LL~
Not the same at all. I know *exactly* what you are talking about, however.
I am not sure why everyone says they have to make a bunch of changes to the 46LA. Jimby got a couple for his Circle King and basically just bolted them into the airplane and they ran like Swiss watches. A lot stronger and more reliable than a Madewell 49, and *that* says "Made Well" right on the side of it!
Brett
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Your missing , many feel the rear mount NVA is not as good as front mounted. I also see the motor is better when you get a NEW NVA and set it up inside the venturie.
Randy
Also, many complains about 46LA out of round liners.
Martin
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Ran both engines. Each one of them is targeted to different airframe sizes/weights. B40 fits in a niche where full-on stunt motors don't venture while LA46 tries to play in the domain of the "big boys". Both PA and RoJett lines of stunt engines, start with .40 size stunt motors that produce a LOT of power and are orders of magnitude better stunt engines.
LA46 is heavy, needs a lot of changes to make it work(venturis, shims, replace cracked plastic backplates with metal ones). No amount of tweaking can change the fact that LA46 is NOT timed for stunt.
B40 on the other hand is light(fox35 light), needs no mods or shims, just proper break-in. It's timed for stunt(4-2-4 style) and enough power to pull any model under 48oz with authority. It will not run in constant two cycle so don't try.
In summary, I think B40 works very well in the model weight/size range it was designed for while LA46 requires a lot of work and cannot compete with stunt engines in the same model weight/size range.
Steve
P.S. When picking a motor, make sure to take into account local motor expertise.
The LA 46 weighs about the same as a G-21 .46, 250+ grams, hardly overweight. The biggest "problem" people have with them is trying to get too much out of them. Running it at its comfortable rpm- 11,000-12,000 it will be a very steady runner. But you're right about planes. The B-40 is comfortable in a Nobler size plane(the engine was designed as a Fox 35 replacement after all) while the LA 46 can pull bigger planes.
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The B-40 is comfortable in a Nobler size plane(the engine was designed as a Fox 35 replacement after all)
Actually, Brother Phil, the Double Star .40 was designed to be an EXACT Fox .35 replacement while I understood from Tom H that the B-40 was aimed at a drop in replacement for the OS .35S. But I know what you meant. LL~ LL~ LL~ LL~ H^^ n~ :##
Mongo
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I am a touch surprised about Stephen's LA46 put down. From what I have seen, the LA46 is hardly "orders of magnitude worse" than a dedicated stunt motor. Provided that you don't try to get the last ounce of power out of them, they run not far short of the expensive dedicated stunt motor, straight out the box. Lets face it a venturi and NVA are hardly a deal breaker.
As for the nasty plastic backplate, most of the damage is done by hamfisted overtightening by enthusiastic pilots. A little RTV is mostly all that is needed. If folk think that doing the above is a big deal, maybe they should go find some other hobby! Me, I shall stick to LA46s (and GP42s!) and use the cash I saved for something else!
Regards,
Andrew.
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I've had such good luck with my two LA46 engines, I'm waiting for an LA61 ! (or how about an LA75?)
Floyd
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Floyd,
How about the LA 65 (RC only, and HEAVY!)??
Jim
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I'd go for the .46LA. Give it a run or two in the plane, on the ground. If it follows the needle and doesn't do anything goofy, then fly it. In about 10 flights, you'll have a very good runner. That's a nice feature! It might take 50 flights to completely stabalize the fuel economy, but that's better than a couple of hours on the bench with a B.40. Plus, you can actually buy a .46LA-S, which is seldom the case with B.40's. Ditto for parts, OBTW.
The B.40 is a better fit for 500~550 sq. in planes, but for larger designs, the .46LA is wonderful. The B.40 seems to be considerably harder to start inverted, especially in cold weather. I sold all 3 of my B.40's, and occasionally pick up a NIB Magnum XLS .36...much like a .46LA, sorta! H^^ Steve
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Steve,
How is your Magnum XLS .36 for starting? Mine will start easy as pie for the first flight of the day, but then is a real bear for the rest of the day, either upright or inverted, without an electric starter. It has plenty of run time, well broken in.
Kim
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P.S. When picking a motor, make sure to take into account local motor expertise.
Yep, that one right there!
Its the reason I chose an MVVS 49, but anyway having a high visibility local flier use a particular type of engine can be very influential.
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Steve,
How is your Magnum XLS .36 for starting? Mine will start easy as pie for the first flight of the day, but then is a real bear for the rest of the day, either upright or inverted, without an electric starter. It has plenty of run time, well broken in.
Kim
HI Kim,
Not Steve, of course, but intrigued with your problem! Aaron has been running two different Magnum .36XLS and we have not had the problem with starting. We just get them "wet" by flipping with the finger over the venturi, and generally get one flip starts through out the day. ???
Bill
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Kim...I've got one XLS .36 inverted, but have only run it a half-dozen tanks at most. The one in the profile has maybe 15 gallons through it (I'm 2nd owner), and it's just amazing for starting...good strings of one-flip starts. This weekend, I just used the electric finger, since I hadn't started it in so long, and it had spent the Winter in a cold garage.
I don't know what you engine's problem is, but it needs to "gurgle" (quite wet) for all starts. Mind you, this drill is for my side mounted one, but I plug the muffler exit with my finger and pull it through 3 times, then thumb over the venturi and do same, then about 6 to 10 flips, listening for the gurgle. I run muffler pressure, of course. Put on the battery, feel for the bump, and signal the judges.... H^^ Steve
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Bill, Steve,
I solved the problem with the Magnum .36XLS (sorry for the hijack, Paul). The culprit, as so often is the case, was the nut holding the chicken stick. LL~ It turns out Steve was right--it wants to be wet, sloppy wet. Even with a nylon diffuser to hold fuel and produce fumes, the best way to prime seems to be flip it over (inverted engine), choke or prime it with the engine upright, then turn it back over and start it on it's wheels. Maybe with enough experience I will be able to learn to get it wet enough without flipping it over, which works fine for now.
Since I'm new to this engine, I'm curious what y'all are using for props and ground rpm. Currently I'm using a Thunder Tiger 11x4.5 at 10K, and getting 4.9 sec laps, a couple of tenths too fast. I suspect I probably need 1/2" less pitch.
Thanks.
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Bill, Steve,
I solved the problem with the Magnum .36XLS (sorry for the hijack, Paul). The culprit, as so often is the case, was the nut holding the chicken stick. LL~ It turns out Steve was right--it wants to be wet, sloppy wet. Even with a nylon diffuser to hold fuel and produce fumes, the best way to prime seems to be flip it over (inverted engine), choke or prime it with the engine upright, then turn it back over and start it on it's wheels. Maybe with enough experience I will be able to learn to get it wet enough without flipping it over, which works fine for now.
Since I'm new to this engine, I'm curious what y'all are using for props and ground rpm. Currently I'm using a Thunder Tiger 11x4.5 at 10K, and getting 4.9 sec laps, a couple of tenths too fast. I suspect I probably need 1/2" less pitch.
Thanks.
Hi Kim,
It DOES need to be wet! ;D
We have only used 4" pitch props. It varies as to diameter, but mainly an 11" 2 blade, or a 10" 3 blade. Haven't tried an APC yet, either. Diameter has been governed by prop clearance so far, mainly in Classic planes which were ground huggers. ;D Haven't tried the "Werwage 10 1/2 X 4 1/2 undercamber", but we use basically the same props we use on the Aero Tiger .36s. Aaron picks his own props (and the engines are basically "his")! LOL!!
I really cannot say about rpm, never tached them. :o
What length lines are you using? Aaron was actually able to fly his Ares at 5.4 with the Magnum on '62' eye to eye .015s. With a GOOD OS .32 previously, the slowest the airplane felt good at was 5.2. The Magnum was just that much stronger!
Big Bear
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Hi BB,
60' eye-to-eye. 5.4 would be living in the lap of luxury! The Vector is a bit oinky at just under 50 oz. I will be experimenting with line lenth and props to find the optimum. I do like to feel the plane solidly out there overhead.
Thanks.
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Hi BB,
60' eye-to-eye. 5.4 would be living in the lap of luxury! The Vector is a bit oinky at just under 50 oz. I will be experimenting with line lenth and props to find the optimum. I do like to feel the plane solidly out there overhead.
Thanks.
Hi Kim,
If the engine is running the way you want, then it just sounds like playing with props. Pitch, especially. All the good guys say the needle is to get the engine running right and the prop/line length is to get the plane at the right flying speed for your tastes. Maybe a slight oversimplification, but that general premise always seems to be the right one. ;D
Some tip weight and line LO adjustments can get the overhead tension right once you get the flying speed right. At 50 oz. it "might" have to fly a bit quick but, as you know, trimming can do tremendous things!
Bill
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Kim, the dreaded Fancherized Twister ("KISS"...the blue & white job...you've seen it several times) weighs around 48 oz. now, and I fly it on 59' eye to eye lines. I have never checked the lap time, because it feels just fine. The TT Cyclone works great for me, launching at 9,700.
One thing to think about, tho. I'm running the .46LA muffler, so it's relatively quiet. If you run the stock Magnum muffler, it will be ok, but a bit louder. If you're running a tongue muffler, well, you know. The thing is, that the quieter the engine/muffler, the slower it sounds, and the slower it feels. Sound is a tricky thing. Ever timed a racer, speed plane or combat model that was really howling...but you found wasn't going very fast when you put the stopwatch on it? Stunt is the same way. I used the LA muffler to balance the plane (almost). If it didn't need that much weight, I'd use one of Randy Aero's CNC Tube mufflers with a rubber ducky on it, even if I had to add some tail weight. H^^ Steve
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Hi Steve, BB,
I had taken a solemn oath never to use props made of black gold$$ (carbon fiber), but a friend let me try an 11 x 4" 3-blader yesterday, and eegad ~^ did the line tension improve up high. Time to whip out the poor, overworked credit card. Sigh. LL~
Am enjoying your posts, as always. H^^
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Hi Steve, BB,
I had taken a solemn oath never to use props made of black gold$$ (carbon fiber), but a friend let me try an 11 x 4" 3-blader yesterday, and eegad ~^ did the line tension improve up high. Time to whip out the poor, overworked credit card. Sigh. LL~
Am enjoying your posts, as always. H^^
They can be a real benefit in some cases. y1
Bill
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I had taken a solemn oath never to use props made of black gold$$ (carbon fiber), but a friend let me try an 11 x 4" 3-blader yesterday, and eegad ~^ did the line tension improve up high. Time to whip out the poor, overworked credit card. Sigh. LL~
I've never used CF prop with B40. A good friend of mine used a Bolly prop on B40 powered Nobler but found that 10.5x4.5 APC was just as good for a fraction of the cost. Later on, he switched to the Thunder Tiger prop which gave him the best performance overhead. I use the TT prop with B40 as well. Consider trying those props first.
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I've never used CF prop with B40. A good friend of mine used a Bolly prop on B40 powered Nobler but found that 10.5x4.5 APC was just as good for a fraction of the cost. Later on, he switched to the Thunder Tiger prop which gave him the best performance overhead. I use the TT prop with B40 as well. Consider trying those props first.
It was a Magnum .36XLS on a 50 oz. plane. I had tried those props and a couple of others. I suspect that prop choice as it relates to line tension gets pickier as weight goes up.
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You can really get into a lot of things when trying different props. Even a small pitch tweak on a CF prop can make a difference, and forget abut wood! LOL!! They can differ even when they are the same make and marked the same! LOL!!
Haven't tried the XOAR props yet, hear they are very good for wood along with the RSM props.
Of course, a 3 blade versus a 2 blade makes a difference, and on and on........... ;D
Big bear
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You can really get into a lot of things when trying different props. Even a small pitch tweak on a CF prop can make a difference, and forget abut wood! LOL!! They can differ even when they are the same make and marked the same! LOL!!
And once you get over the hump of crashing a lot, they actually are a decent value. Aside from one freak incident at Tucson a few weeks ago, I lose props only when I crash the airplane. I have been using the same 3 props for the last 5-6 years and have had them tweaked all over the place. You can do similar tweaks with wood props, but you have to use one prop per tweak. That can add up, both in cost and more importantly, time. It takes a few minutes to tweak a graphite or fiberglass prop, and it takes an hour-ish to put a similar tweak on a wood prop - because you have to start from scratch every time.
Brett
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And once you get over the hump of crashing a lot, they actually are a decent value. Aside from one freak incident at Tucson a few weeks ago, I lose props only when I crash the airplane. I have been using the same 3 props for the last 5-6 years and have had them tweaked all over the place. You can do similar tweaks with wood props, but you have to use one prop per tweak. That can add up, both in cost and more importantly, time. It takes a few minutes to tweak a graphite or fiberglass prop, and it takes an hour-ish to put a similar tweak on a wood prop - because you have to start from scratch every time.
Brett
I agree about the CF, etc., props. One you have them, they last forever barring incidents! I think I remember Ted mentioning that he tweaked them using real hot water. ??
Aaron once broke a three blade taking the plane out of the van, he caught it on something and unfortunately, it was the only one of that size we had with us. We always take them off the engines now once the flying is over! LOL!!
I use to sit around in the evening watching TV with the wife and sand/carve on wood props, just don't do that anymore.
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And once you get over the hump of crashing a lot, they actually are a decent value....
Brett
As a funny follow-up to this, my first CF prop lasted about 15 minutes. After the first flight last weekend, when I experienced the difference in line tension, I asked a friend with a very low crash frequency to fly it and give me his impressions and any trim suggestions. For some reason we haven't figured out, when down control was applied for the inverted wingover pullout, nothing (or very little) happened (speaking of freak accidents). The nose buried itself in soft, friendly mud thanks to early morning sprinkling of the field, shattering the prop, popping the landing gear mount off, but leaving the rest of the plane undamaged. "If she don't 'splode when she crashes..." etc. We checked the controls, but couldn't find anything wrong.
I'm taking this as a "reverse omen". My CF prop dues are now paid up for some time to come. However, with a possible undetected control system bind lurking for a second strike, common sense will also be used, and omens not depended upon.
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I agree about the CF, etc., props. One you have them, they last forever barring incidents! I think I remember Ted mentioning that he tweaked them using real hot water.
Oh, yeah, that's the only reliable way to actually get what you want. Mostly because you can control what part of the blade gets hot.
Brett
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HI Kim,
Between Aaron and myself, we have broken 5 CF props in almost 20 years of usage. We have kept the broken ones, and we have been very lucky! 4 from flying mishaps and one from a "van mishap"! LOL!!!!!!
Once I was told they were a "status symbol" LOL!!!!!!! I just think that they (and other "molded" props) are the way to go 99% of the time. They just have so many advantages over wood.
Bill
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I have to agree about CF prop longevity. I just didn't see much performance difference between a CF and TT props on B40 motor.
I have stopped using wood props when I stopped crashing. When I was learning to fly inverted, I bought a dozen props from tower hobbies and proceeded to break every single one of them. My record was 5 broken props in one field outing.
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I have to agree about CF prop longevity. I just didn't see much performance difference between a CF and TT props on B40 motor.
I have stopped using wood props when I stopped crashing. When I was learning to fly inverted, I bought a dozen props from tower hobbies and proceeded to break every single one of them. My record was 5 broken props in one field outing.
HI Steven,
I have never had a TT prop. They ARE molded though, right? If it is molded or CF seems to make little difference in some cases, but not being wood is a MAJOR difference in most cases.
Now, of course, Yuriy only uses wood, right? ;D
Bill
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Now, of course, Yuriy only uses wood, right?
One thing that struck me after playing around with Orestes engine for a few minutes is that the moment of inertia of the Yatsenko prop/spinner is tiny. The props are incredibly light and the spinner must not be much, either.
The engine is remarkably free through the bottom end of travel, too.
Brett
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HI Brett,
On the Yatsenko site, Yuriy goes into a bit about why he prefers wood. Just a thought thrown out to Steven since he is fluent in "Russian"! ;D
Bill
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I personally flew and setup a Yat. Shark with the stock wood props and then a light 13 inch CF prop, the plane performed much better with the CF prop in light winds and way better in heavy winds, It was also much more consistant in going thru manuavers with the CF prop, and you could feel the wood prop depitching and fluttering\buzzing (feel in the handle, and see the slowdown in corners) when the higher winds would really load it in turns, The CF prop didn't do this.
So ya pays your money and take what you get. I would have liked to have setup a CF prop with the larger diameter that the wood ones had, I would expect even more performance in less than ideal condidtions. I have done this with 1 Shark, but it didn't have the DR 60 in it
Regards
Randy
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Great thread; sorry I was off line for awhile and missed the beginning.
Yea, like most I have both, and have found that the B40 will not start inverted, or when hot, but does give a great 4-2-4 break. The LA46 really is a "one-flip" engine and gives very consistant runs, but is heavy. I've had no backplate issues and find the remote needle just fine; haven't tried anything different however.
As for props; the B40 spinning an RSM 10/6 gave great performance on a Super Chipmonk (51.5 oz). After reading a thread about the Vess props I tried a Vess 10/6. What a dissapointment. I had to run the B40 on a hard 2 stroke to get the same lap times; it was like the Vess couldn't bite into the air at all. I've since tried old Top Flite 10/6 (from the 60's) and found it's performance on par with the RSM . . . or is the performance of the RSM on par with the Top Flite?
If I could have only one . . . probably the LA46; then build slightly bigger airplanes . . . but I really like both.
Brian
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I personally flew and setup a Yat. Shark with the stock wood props and then a light 13 inch CF prop, the plane performed much better with the CF prop in light winds and way better in heavy winds, It was also much more consistant in going thru manuavers with the CF prop, and you could feel the wood prop depitching and fluttering\buzzing (feel in the handle, and see the slowdown in corners) when the higher winds would really load it in turns, The CF prop didn't do this.
So ya pays your money and take what you get. I would have liked to have setup a CF prop with the larger diameter that the wood ones had, I would expect even more performance in less than ideal condidtions. I have done this with 1 Shark, but it didn't have the DR 60 in it
Regards
Randy
HI Randy,
It would appear to "me" that a wood prop could not be as rigid as a CF prop, and would suffer more "flex" under varying loads. Maybe a wood prop "could be as stiff, but then it would have to weight more, or be of some wood that I am not familiar with. ;D
Is that correct?
Thanks!
Bill
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HI Randy,
It would appear to "me" that a wood prop could not be as rigid as a CF prop, and would suffer more "flex" under varying loads. Maybe a wood prop "could be as stiff, but then it would have to weight more, or be of some wood that I am not familiar with. ;D
Is that correct?
Thanks!
Bill
Correct Bill
That is the main reason people pay for a CF prop, They are very stiff and thin. The new RSM Props are great for wood props, some of the most stiff vs. thickness of most wood props I have seen lately
Randy
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" and have found that the B40 will not start inverted,"
Brian
Glad my inverted B40's haven't read this....... ;D
Jim
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" and have found that the B40 will not start inverted,"
Brian
Glad my inverted B40's haven't read this....... ;D
Jim
Besides putting blinders on your B40's, what's your technique/secret?
Brian
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Great thread; sorry I was off line for awhile and missed the beginning.
Yea, like most I have both, and have found that the B40 will not start inverted, or when hot, but does give a great 4-2-4 break. The LA46 really is a "one-flip" engine and gives very consistant runs, but is heavy. I've had no backplate issues and find the remote needle just fine; haven't tried anything different however.
As for props; the B40 spinning an RSM 10/6 gave great performance on a Super Chipmonk (51.5 oz). After reading a thread about the Vess props I tried a Vess 10/6. What a dissapointment. I had to run the B40 on a hard 2 stroke to get the same lap times; it was like the Vess couldn't bite into the air at all. I've since tried old Top Flite 10/6 (from the 60's) and found it's performance on par with the RSM . . . or is the performance of the RSM on par with the Top Flite?
If I could have only one . . . probably the LA46; then build slightly bigger airplanes . . . but I really like both.
Brian
Wood props can come with a lot less or a lot more pitch then it is marked. When I used them would have to buy many props to get the ones with the right pitch. At the end it was a good thing, because I end up with a set of props ranging from 5 to 8 in pitch that I could pick depending on wind and climate conditions. Some of the TopFlite 14x6 I measured had 8 pitch in one blade and 5.5 in the other. My 4S engine would run much better with a light wood prop than with a CF one, so I kept on buying wood props.
The reason is very simple, when the propeller cutting machine cuts the wood fibers that wood stick will warp in any direction.
The JXF props were the most accurate ones I tried, among TopFlite and Zinger.
Before you give up on the VESS prop, try to find out the real pitch of the prop you used and try a different one.
Martin
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Before you give up on the VESS prop, try to find out the real pitch of the prop you used and try a different one.
Martin
I've never measured prop pitch; is there a simple way, or somewhat inexpensive tool to do that?
Thanks, Brian
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I've never measured prop pitch; is there a simple way, or somewhat inexpensive tool to do that?
Thanks, Brian
hi Brian,
There was a simple to make, pretty accurate prop pitch gauge published in one of the magazines a few years ago. I hope someone here posts that for you.
I have had a Prather Pitch gauge for many years, so I didn't build one, myself. I don't "know" of an easy way to do it with out a "gauge"......
I have seen the Prather gauges on ebay, and I think some one has made them from time to time for sale. Randy Smith might still have some, I don't know.
If you are going to be "serious" about contest flying, I think you really need to find one. All props can be "off", which means you might have to go through a big bunch of them finding the "right" one if you don't have a gauge. And if you go to the CF props, only a couple of them are needed since you can easily repitch them with a gauge.
Big Bear
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Thanks Bill; I'll contact Randy to start the search.
While I will never be challenging the likes of Dave F, I do want to get better. My goal is to fly in advanced without embarrassing myself too much.
Brian
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Hi guys,
If you look on the ukie control site, he has a pitch gauge that ya can make. Check it out looks kinda cool. Darn I have to leave ya cause I just have to go and play in this darn 70 degree weather with the sun beating down. I guess some guys have all the luck????
Have a great day!!!!
Gary
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Anyone got a URL for Ukie Control Line?
Brian
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Anyone got a URL for Ukie Control Line?
Brian
Hi Brian,
On my computer I typed in Ukie Control Line in the Google box and ukie comes up. Open up the Ukie Home Page and click on workshop and there is several nice little items to check out. Give it a try and let me know how it works out for you. Sure was a nice day to play with our toys. Thanks for coming out to play, see ya Sunday.
Gary
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Brian,
No secrets; maybe just lucky!
I use 10/22 (50/50), metal uniflow (no exhsut pressure), stock muffler, various props and 2 layers of the thin part of panty hose material ever the venturi. We are about 250 ft. above sea level--if that matters, near Montgomery, AL.
When I fill the tank, I use a hand crank pump and make sure that I get a drip or three from the venturi as well as slight flow from the tank overflow. Then I choke with a finger 3 or 4 revolutions---make sure there is fuel on my finger after choking. Attach battery, pull thru until I get a bump--usually one or three blades, then flip. Usually one to three flip starts---if it seems a bit wet, I will back flip for starting.
Very seldom will the engine need more than a flip or three to start, with a hot battery. Usually use a Thunderbolt RC plug, but have had good results with the OS LC3 (car plug, but very hot according to OS heat chart).
Cheers,
Jim
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I built the Hooptee Pitch guage, neat project, works good..
http://stunthanger.com/smf/index.php?topic=11210.0
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I am a touch surprised about Stephen's LA46 put down. From what I have seen, the LA46 is hardly "orders of magnitude worse" than a dedicated stunt motor. Provided that you don't try to get the last ounce of power out of them, they run not far short of the expensive dedicated stunt motor, straight out the box. Lets face it a venturi and NVA are hardly a deal breaker.
As for the nasty plastic backplate, most of the damage is done by hamfisted overtightening by enthusiastic pilots. A little RTV is mostly all that is needed. If folk think that doing the above is a big deal, maybe they should go find some other hobby! Me, I shall stick to LA46s (and GP42s!) and use the cash I saved for something else!
Regards,
Andrew.
I put 242 Loctite (removeable type)on the backplate screws after I had them come loose soon after I started using the LA 46. Haven't had them come loose since then and it's been about 2 years. I have mine on a SIG Banshee with a 12-4 Master Airscrew. I could probably use a 12-3 to slow the plane down a bit. Great engine. Starts first or second flip and I rarely have to adjust the needle valve. Lots of power and it runs the same every time.