31
Open Forum / Re: Similar Terminology
« Last post by Steve Dwyer on Today at 06:33:29 AM »I've heard an expert say close one eye when caught trying to eclipse the sun with your model. Light adaptation can vary depending on the individual.
- June 30, 2025, 05:19:57 PM
Recent Posts
32
Open Forum / Re: ST 35 Combat's sleeve orientation
« Last post by Paul Smith on Today at 06:22:48 AM »Very true.
In all 2-stroke engines it is necessary to allow the hot compressed exhaust to leave the combustion chamber before the cool low pressure incoming charge can enter.
In all 2-stroke engines it is necessary to allow the hot compressed exhaust to leave the combustion chamber before the cool low pressure incoming charge can enter.
33
Paint and finishing / Re: Flight test before paint
« Last post by kevin king on Today at 05:56:46 AM »Any suggestions or cautions? It’s a Pinto / Norvel Big Mig combo with silkspan. Nitrate underneath and butyrate top coat now. Need to fly it before making it pretty.Usually the model is painted before you fly it. Good luck getting any paint to stick if you do go ahead with flying it before finishing it.
Thanks.
Dave Mo…
34
Open Forum / Re: ST 35 Combat's sleeve orientation
« Last post by kevin king on Today at 05:26:38 AM »Thanks Massimo! 
35
Classifieds / (8) Used Thunder Power ProLiteX 6-cell 2800 mAh Batteries
« Last post by Dennis Nunes on Today at 05:23:31 AM »For sale: 8 Used Thunder Power ProLiteX 6-cell 2800 mAh batteries with XT-60 connectors in good condition. $350.00 includes shipping. Sorry continental U.S. only.
Two of the batteries are the older lightweight packs. The other six are the newer packs.
Will accept PayPal (Friend/Family) or Zelle for payment.
Dennis
Two of the batteries are the older lightweight packs. The other six are the newer packs.
Will accept PayPal (Friend/Family) or Zelle for payment.
Dennis
36
Open Forum / Re: Li-on vs Li-po?
« Last post by Dennis Nunes on Today at 04:59:53 AM »It is not a trivial difference - I think Dennis and Jim saved something like 2 ounces and the gaps kept the cells much cooler.
Brett
As usual, Brett is correct. I was using Thunder Power ProLiteX 6-cell 2800 mAh batteries in my Circulas 61e. I have some of the older TP 6-cell battery that weigh 12.30 oz. Thunder Power's current 6-cell batteries weigh 13.00 oz. This is .7 oz heavier and .125" taller than the older packs. Some modelers, with tight clearances for their batteries, found out the hard way when they received the new TP batteries and would fit in their models.
My latest Li-Ion 6-cell battery packs that I've made weigh 10.70 oz. These packs use the Molicel INR-18650-P30B 3000 mAh cells. These packs are 2.30 oz. lighter and have more capacity than the TP packs, which is substantial. These packs, so far, have worked extreme well.
One clarification, Jim (Uncle Jimby) and Howard Rush have made 5-cell and 6-cell Li-Ion packs with end caps (no shrink wrap around the pack) that create space between each cell for cooling. I'm still making the "traditional" triangle shape 6-cell packs with shrink wrap (no spacing).
Dennis
ps: I have 8 Used Thunder Power ProLiteX 6-cell 2800 mAh batteries with XT-60 connectors in good condition for sale. See https://stunthanger.com/smf/classifieds-92/8-used-thunder-power-prolitex-6-cell-2800-mah-batteries/ for further information.
37
Open Forum / Re: Has anybody used one of these?
« Last post by Lauri Malila on Today at 03:39:59 AM »[quote author=Brett Buck
We have done it a few times and found nothing that surprised us. It might surprise others - because, for example, when your 4-2 engine breaks into a 2-stroke, it is down something like 200-500 RPM *slower* that level flight where it was 4-stroking, and in some cases it is blubbery rich and running 500 rpm *more* than level flight speed.
Brett
[/quote]
That’s absolutely not always the case, a well set Retro, Stalker or even ST will increase the RPM when it shifts to 2-stroke from 4-stroke. Usually about 200rpm. That has been tested many times.
I saw the same drop when experimenting with Schnuerle scavengings, it was more difficult to have a reliable & positive shift.
But with big engines it’s not a problem as there is power, and you’ll need the more constant ”2-stroke mode” during maneuvering, rather than a blubbery rich 4-stroke even when the 4-stroking is capable to deliver enough power.
I think the reasons are, that modern Schnuerle engines that are de-tuned for stunt, quickly loose their scavenging efficiency & stability when operated below the ideal power range. What determines the power and stability is mainly the scavenging & port cross area, and especially with big engines it is very difficult to design a schnuerle scavenging that suits our needs.
Another thing that has an enormous effect in 2-4 shift is the piston/cylinder fits & alloying. In general;
-Higher Si% in piston = more aggressive shift
-More cylider conicity = more aggressive shift
It’s quite complicated.
We have done it a few times and found nothing that surprised us. It might surprise others - because, for example, when your 4-2 engine breaks into a 2-stroke, it is down something like 200-500 RPM *slower* that level flight where it was 4-stroking, and in some cases it is blubbery rich and running 500 rpm *more* than level flight speed.
Brett
[/quote]
That’s absolutely not always the case, a well set Retro, Stalker or even ST will increase the RPM when it shifts to 2-stroke from 4-stroke. Usually about 200rpm. That has been tested many times.
I saw the same drop when experimenting with Schnuerle scavengings, it was more difficult to have a reliable & positive shift.
But with big engines it’s not a problem as there is power, and you’ll need the more constant ”2-stroke mode” during maneuvering, rather than a blubbery rich 4-stroke even when the 4-stroking is capable to deliver enough power.
I think the reasons are, that modern Schnuerle engines that are de-tuned for stunt, quickly loose their scavenging efficiency & stability when operated below the ideal power range. What determines the power and stability is mainly the scavenging & port cross area, and especially with big engines it is very difficult to design a schnuerle scavenging that suits our needs.
Another thing that has an enormous effect in 2-4 shift is the piston/cylinder fits & alloying. In general;
-Higher Si% in piston = more aggressive shift
-More cylider conicity = more aggressive shift
It’s quite complicated.
38
Open Forum / Re: ST 35 Combat's sleeve orientation
« Last post by Massimo Rimoldi on Today at 12:02:13 AM »Hello.
In all 2S engines the highest window is the exhaust one, the lowest one (or ones) is the transfer window.
In your case the single window is the exhaust, the two coupled ones are the transfer ports.
Massimo
In all 2S engines the highest window is the exhaust one, the lowest one (or ones) is the transfer window.
In your case the single window is the exhaust, the two coupled ones are the transfer ports.
Massimo
39
Open Forum / Re: Li-on vs Li-po?
« Last post by Brett Buck on Yesterday at 10:13:16 PM »Anybody that can feel 1 gram of tip weight in wind has to have a better battery box.
The way that went was Ted and I were wandering by the circle during a Howard practice flight, and I guessed that he needed about 2 grams, just casually eyeballing it. He added 3, then it started hinging the other way.
I had nothing to do with it, so I will let those involved show what they want to. It is not a trivial difference - I think Dennis and Jim saved something like 2 ounces and the gaps kept the cells much cooler.
Brett
40
Open Forum / Re: I painted my fuel can
« Last post by kevin king on Yesterday at 09:58:45 PM »MOTORHEAD!Thanks, glad you like it! 🤘😃🤘. Will upload some pictures soon.
I love your Lemmy scheme Vector. Very nice.