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08-28-2014, 10:38 AM
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This may have been discussed already, but if nitro is mainly used as an ignition advancer, couldn't that function be performed by the electronic ignition timing? Or does the nitro allow for even more advanced timing, and consequently, higher brake torque (not to mention cooling because of the endothermic reaction it creates).
When I ran the same combo on 30% O'Donnell Speed Blend, the RPM increased to 8850.
The 2 pulls were done back to back on the same day.
08-28-2014, 10:52 AM
I learned about using epoxy by accident when fuelproofing a firewall and getting it in the blindnut threads. Now, I use it on engine backplates, those blindnuts, and for the threaded muffler attach bolts. I mix it up normally and swab some in the threads and let it dry. Bolts will thread right in and stay put. No vibrating out anymore. The epoxy gets chewed up some when you thread in a bolt and holds. I think the advantage is that it gets screwed into boogers , has better mass in the threads, and just stays there holding the threads like thousands of little blobs. It doesn't harm anything.
The DC-10 got a bad PR rap. If you look they are still flying the crap out of them for freight, FedX, etc.
Okay, maybe a bare metal Connie looked pretty good like the all metal DC-3. I saw one of those a few years ago. The all metal finish B-25 is beautiful too.
I flew in a Constellation when I was about 8 years old. I saw Gen. Douglas MacArthur's Connie take off from a short field at Fort Rucker when the Army sold it to a private company in the late 1980's. It had sat outside at the museum for decades. I would see it outside my window every day when I was in flight school. Some mechanics got it barely flight worthy for a short hop for extended maintenance about 20 miles south. They dropped the chain link fence at the end of the runway but the 12' poles stayed in the ground. I was there at 6 am with a crowd to watch. The pilot ran up those engines and I wished he would just stay there and let me listen all morning. The runway was less than 2000' and he barely rumbled down it. It looked like a magic trick when he did a clean and jerk takeoff. He yanked back on the yoke and up came the nose and it jumped up in the air. The wheels and wings cleared the fence poles by mere feet. He didn't raise the gears and headed straight towards Dothan Airport staying at about 200'. What a sight and what a beautiful sound!
The DC-10 got a bad PR rap. If you look they are still flying the crap out of them for freight, FedX, etc.
Okay, maybe a bare metal Connie looked pretty good like the all metal DC-3. I saw one of those a few years ago. The all metal finish B-25 is beautiful too.
I flew in a Constellation when I was about 8 years old. I saw Gen. Douglas MacArthur's Connie take off from a short field at Fort Rucker when the Army sold it to a private company in the late 1980's. It had sat outside at the museum for decades. I would see it outside my window every day when I was in flight school. Some mechanics got it barely flight worthy for a short hop for extended maintenance about 20 miles south. They dropped the chain link fence at the end of the runway but the 12' poles stayed in the ground. I was there at 6 am with a crowd to watch. The pilot ran up those engines and I wished he would just stay there and let me listen all morning. The runway was less than 2000' and he barely rumbled down it. It looked like a magic trick when he did a clean and jerk takeoff. He yanked back on the yoke and up came the nose and it jumped up in the air. The wheels and wings cleared the fence poles by mere feet. He didn't raise the gears and headed straight towards Dothan Airport staying at about 200'. What a sight and what a beautiful sound!
08-28-2014, 11:59 AM
Getting higher output with higher nitro is expected. I just wonder if that same performance increase can be achieved with lower nitro but advancing the ignition timing. I suspect that the nitro helps with achieving the higher performance without causing excess heat like advancing the ignition timing would cause. The nitro content in combustion cools down the gasses (absorbs the combustion heat?), allowing for higher performance at lower temps.
Last edited by hsukaria; 08-28-2014 at 12:02 PM.
08-28-2014, 02:02 PM
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08-28-2014, 02:50 PM
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Sammy, what OS had a glo plug in the front? Only 4 stroke I've seen with a plug in the front is an Enya.
Old Fart, do you mean the Saito 30 or the SC 30 clone? The SC 30 clone will rev but not sustained and not for long hence the tag "grenade" Saito 30 is good for 12K for ever but not much more sensibly.
That car OS 26 is an interesting piece of work, bigger valves (marginal) stronger springs, ceramic piston etc and not at all cheap.
If you want you engines to go faster in the following order, use more nitro, use more viscous oil (like Cool power heli oil) better props and finally ceramic pistons etc. Props help and with the appropriate type you can even hear them unload as they get going in flight and pick up revs
Old Fart, do you mean the Saito 30 or the SC 30 clone? The SC 30 clone will rev but not sustained and not for long hence the tag "grenade" Saito 30 is good for 12K for ever but not much more sensibly.
That car OS 26 is an interesting piece of work, bigger valves (marginal) stronger springs, ceramic piston etc and not at all cheap.
If you want you engines to go faster in the following order, use more nitro, use more viscous oil (like Cool power heli oil) better props and finally ceramic pistons etc. Props help and with the appropriate type you can even hear them unload as they get going in flight and pick up revs
08-28-2014, 03:14 PM
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Hello Ernie,
Regarding epoxy as threadlocker, I've done it but not for model aircraft. We used it on coupling rings for large electrical connectors. The trick was to screw the connector all together until you only have one or two threads left. Then mix up a SMALL batch of epoxy. We would put a single drop on some threads using a toothpick (no lie!) and then finish screwing the connector together. The epoxy would spread out. That small dab was enough!
If you ever had to take the connector apart, you would use a heat gun to heat up the epoxy and soften it. Then clean it out before you re-assembled the connector. If you used more than I mentioned, you would NEVER get the connector apart without some type of damage due to the heat you 'd have to use, or to the wrenches you'd need to turn it.
It goes without saying that both mating threads were clean and free of grease and oil...
Just my $.02
Bob
Regarding epoxy as threadlocker, I've done it but not for model aircraft. We used it on coupling rings for large electrical connectors. The trick was to screw the connector all together until you only have one or two threads left. Then mix up a SMALL batch of epoxy. We would put a single drop on some threads using a toothpick (no lie!) and then finish screwing the connector together. The epoxy would spread out. That small dab was enough!
If you ever had to take the connector apart, you would use a heat gun to heat up the epoxy and soften it. Then clean it out before you re-assembled the connector. If you used more than I mentioned, you would NEVER get the connector apart without some type of damage due to the heat you 'd have to use, or to the wrenches you'd need to turn it.
It goes without saying that both mating threads were clean and free of grease and oil...
Just my $.02
Bob
08-28-2014, 03:28 PM
Sammy, what OS had a glo plug in the front? Only 4 stroke I've seen with a plug in the front is an Enya.
Old Fart, do you mean the Saito 30 or the SC 30 clone? The SC 30 clone will rev but not sustained and not for long hence the tag "grenade" Saito 30 is good for 12K for ever but not much more sensibly.
That car OS 26 is an interesting piece of work, bigger valves (marginal) stronger springs, ceramic piston etc and not at all cheap.
If you want you engines to go faster in the following order, use more nitro, use more viscous oil (like Cool power heli oil) better props and finally ceramic pistons etc. Props help and with the appropriate type you can even hear them unload as they get going in flight and pick up revs
Old Fart, do you mean the Saito 30 or the SC 30 clone? The SC 30 clone will rev but not sustained and not for long hence the tag "grenade" Saito 30 is good for 12K for ever but not much more sensibly.
That car OS 26 is an interesting piece of work, bigger valves (marginal) stronger springs, ceramic piston etc and not at all cheap.
If you want you engines to go faster in the following order, use more nitro, use more viscous oil (like Cool power heli oil) better props and finally ceramic pistons etc. Props help and with the appropriate type you can even hear them unload as they get going in flight and pick up revs
08-28-2014, 05:26 PM
I was just looming on the O.S. chat and found a photo of this engine. They are saying that is a Surpass .90 Engine. I.m running a 13X8-14X10 on both. I still like the Satio! Like t have a Satio tween for this Aerrws QB 260 l won. Also a tween in the Sboch! It has a WS of 67in, a 20cc plane. The Aw, has a WS of is 76 in, a 30cc plane. Would do some tradding of a low time DLE55 with Pitts muffler. Don't have a tween, the QB needs a ? 180 or bigger same with that Sbach.
08-28-2014, 08:40 PM
The original non-Surpass OS 90 had the pushrods and cam at the rear and plug in the front. Sold one quite a while ago as even the first Surpass had quite a lot more power.
The Saito 91 would still outperform an S2. Not sure of the latest version Surpass.
The Saito 91 would still outperform an S2. Not sure of the latest version Surpass.
08-28-2014, 08:51 PM
That's the one. Runs and has lots of power, just likes to bite when you remove the glow starter!
08-28-2014, 11:27 PM
Sammy, what OS had a glo plug in the front? Only 4 stroke I've seen with a plug in the front is an Enya.
Old Fart, do you mean the Saito 30 or the SC 30 clone? The SC 30 clone will rev but not sustained and not for long hence the tag "grenade" Saito 30 is good for 12K for ever but not much more sensibly.
That car OS 26 is an interesting piece of work, bigger valves (marginal) stronger springs, ceramic piston etc and not at all cheap.
If you want you engines to go faster in the following order, use more nitro, use more viscous oil (like Cool power heli oil) better props and finally ceramic pistons etc. Props help and with the appropriate type you can even hear them unload as they get going in flight and pick up revs
Old Fart, do you mean the Saito 30 or the SC 30 clone? The SC 30 clone will rev but not sustained and not for long hence the tag "grenade" Saito 30 is good for 12K for ever but not much more sensibly.
That car OS 26 is an interesting piece of work, bigger valves (marginal) stronger springs, ceramic piston etc and not at all cheap.
If you want you engines to go faster in the following order, use more nitro, use more viscous oil (like Cool power heli oil) better props and finally ceramic pistons etc. Props help and with the appropriate type you can even hear them unload as they get going in flight and pick up revs
ps trev if we drive over to the nats next year with a trailer i'll throw the duke on as well.Then we can do a lap over the mountain at bathurst,got a spare helmet? for our american cousins the downhill section off the mountain leading on to conrod straight is similar to the famous laguna seca corkscrew but steeper and much longer,it's a hoot.
08-29-2014, 03:45 AM
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Now, as to using epoxy as a thread locker, if you've ever used a metal rod to stir epoxy, you'll note that epoxy is slick on things it can't soak into. It will just slide off. (Even when set up/hard) So I don't see it being effective at holding anything metal.
08-29-2014, 04:38 AM
I was under the impression the rev limits on these engines had to do with valvetrain design and inertia. With those rather light single wind springs valves would have a tendency to float and bounce.
I would advise against using anything other than the rather poor 5-minute epoxy available at your corner store for fastener retention purposes. The bonding properties of epoxy include a structural element, created by the formation of long-chain molecules within the matrix. That formation takes time and can be increased by mixing in supplements with similar properties, (FLOX or AEROSIL). Unfortunately, most 5-minute epoxies like described never seems to hold up and are extremely brittle. This may be fine for holding a fastener, but what about the alloy parent metal? I would think removal of the fastener without adequate softening with heat would or could tear the threads out of the case if aggressive enough. And about heating: I would suspect the temps these epoxies would begin to soften and lose the intended properties would be reached during normal operation, hence the fasteners could come loose anyway
I find the level of discussion about keeping bolts tight surprising. I think in all 3 decades I personally can count the number of times this has happened ON MY OWN ENGINES on one hand. In a properly designed application a correctly torqued fastener should NOT come loose under normal circumstances.
Mind you, I have seen quite a lot of bolts come loose, but remember the prior statement in its entirety.
With Loctite available for pretty much any application, (with information widely available online) in small enough bottles to be cost effective, no reason I can think of to go with non purpose-designed compounds.
I would advise against using anything other than the rather poor 5-minute epoxy available at your corner store for fastener retention purposes. The bonding properties of epoxy include a structural element, created by the formation of long-chain molecules within the matrix. That formation takes time and can be increased by mixing in supplements with similar properties, (FLOX or AEROSIL). Unfortunately, most 5-minute epoxies like described never seems to hold up and are extremely brittle. This may be fine for holding a fastener, but what about the alloy parent metal? I would think removal of the fastener without adequate softening with heat would or could tear the threads out of the case if aggressive enough. And about heating: I would suspect the temps these epoxies would begin to soften and lose the intended properties would be reached during normal operation, hence the fasteners could come loose anyway
I find the level of discussion about keeping bolts tight surprising. I think in all 3 decades I personally can count the number of times this has happened ON MY OWN ENGINES on one hand. In a properly designed application a correctly torqued fastener should NOT come loose under normal circumstances.
Mind you, I have seen quite a lot of bolts come loose, but remember the prior statement in its entirety.
With Loctite available for pretty much any application, (with information widely available online) in small enough bottles to be cost effective, no reason I can think of to go with non purpose-designed compounds.
Last edited by Cougar429; 08-29-2014 at 04:42 AM.
08-29-2014, 04:46 AM
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Cougar, I never use 5 minute epoxy, I only have 30 minute and 3 hour and I only use Bob Smith adhesives. I should clarify that a little, I use SuperPhatic for ribs. You can build an LT 25 in it entirety using the SuperPhatic, even the firewall. As to using epoxy for bolts, I personally wouldn't trust it.
08-29-2014, 04:50 AM
Hobbsy, that was my point entirely. I would think using epoxy that does NOT have time to build adequate long-chain molecules the only option in that case. Anything with better structural qualities would be more difficult to work with or have more chance to damage the case threads during removal. And yes, there are structural adhesives that do a wonderful job of bonding to even smooth metal surfaces.
Again, in my last statement, with Loctite why use anything else?
Again, in my last statement, with Loctite why use anything else?
08-29-2014, 06:06 AM
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Thanks Cougar, as the old saying goes, you nailed it, my one time using Blue Locktite on exhaust threads was on an Enya .46MKII which I still own and it now has snaggle tooth looking exhaust threads because part of the threads came out with the exhaust pipe. Using Teflon Plumbers tape since that there has not been a problem.
08-29-2014, 06:30 AM
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Teflon tape is the thing for exhaust threads, but more important is the mounting configuration so that the weight of the muffler is not unscrewing the pipe. The old "oz of prevention" thing.
On inverted applications small/medium block singles the weight will tend tighten the threads if the muffler is angled sharply out the port side towards the rear while big blocks it will tend to loosen them if angled sharply to the port side. Big blocks work best W/the exhaust pointing down & to the rear while inverted.
Of course upright will be just the opposite while mounted W/the cylinder out the starboard side will favor all sizes W/exhausts angled to the starboard side.
This is true for the straight "tomato can" mufflers only. I hate the angled mufflers as they complicate mounting within the cowl.
However, 90° Adaptors can make for really tidy installation W/both the OEM tomato can or Turboheader mufflers.
On inverted applications small/medium block singles the weight will tend tighten the threads if the muffler is angled sharply out the port side towards the rear while big blocks it will tend to loosen them if angled sharply to the port side. Big blocks work best W/the exhaust pointing down & to the rear while inverted.
Of course upright will be just the opposite while mounted W/the cylinder out the starboard side will favor all sizes W/exhausts angled to the starboard side.
This is true for the straight "tomato can" mufflers only. I hate the angled mufflers as they complicate mounting within the cowl.
However, 90° Adaptors can make for really tidy installation W/both the OEM tomato can or Turboheader mufflers.
Last edited by SrTelemaster150; 08-29-2014 at 06:34 AM.
08-29-2014, 02:39 PM
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Old Fart, when Conrod Straight was straight I once went around with Brokky in the Monaro followings Moffat in the GT Falcon and seeing him get airborne at the vineyard followed by us doing the same thing and coming to a grinding halt which was followed by expletives best not repeated I came to understand Zen and the art of racing cars. The rear r/h axle was twisted like a pretzel caused by the impact of the rear whells spinning at who knows what RPM hitting the road. Not like that now and to think the kink was put in "to save lives" and killed the only "saloon car" driver ever the next year.
Nw back to topic. The OS units had better valve springs and better valve seat inserts (I don't know if they are standard) and ran high nitro. Did same thing with SC 30 4 stroke and it blew apart. Not interested in that line of action any more. Off to scale event now a w/end do Catch Ya.
Nw back to topic. The OS units had better valve springs and better valve seat inserts (I don't know if they are standard) and ran high nitro. Did same thing with SC 30 4 stroke and it blew apart. Not interested in that line of action any more. Off to scale event now a w/end do Catch Ya.
08-30-2014, 02:39 AM
What if barry is right .He and others say heat softens epoxy and that works for me too in the paint world which is my job.If the heat softens epoxy it would grip steel well.