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Old 11-16-2017, 12:54 AM
  #26  
Mark Powell
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Originally Posted by Ixtrim View Post
Pure Music :-)........
Unfortunately they sing very out of tune

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Old 11-16-2017, 01:41 AM
  #27  
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Originally Posted by Mark Powell View Post
Unfortunately they sing very out of tune

https://www.youtube.com/watch?v=Y5rGyP6SSYM
maybe... a Little bit :-)


feel free to Show us a model engine sounding closer to the real Thing than the 3zyl
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Old 11-16-2017, 02:31 AM
  #28  
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Originally Posted by Ixtrim View Post
maybe... a Little bit :-)


feel free to Show us a model engine sounding closer to the real Thing than the 3zyl
Actually I think that up to about '120' size (20 cc) a four-stroke single sounds more realistic. Because the number of firing strokes per second, thus the frequency, over its operational RPM range is closer (but slightly lower) to the frequency of a Merlin/Griffon over its operational RPM range.

But as the RPM decreases with size a four-stroke flat twin, which always has evenly spaced firing strokes is better than a single at larger sizes. Or a '360 degree' in-line twin (think 1960's British motorcycles) where the two pistons go up and down together but fire alternately, so again give evenly spaced firing strokes.

Four-stroke triples can't have even firing strokes so their sound frequency varies in an unrealistic 'rhythmic' manner, which explains their uneven (and thus unrealistic sounding) tickover/low speed operation and overall their sound frequency is too high.

A guy at our model site used to fly a Hawker Sea Fury with a 7 cylinder 250 cc Moki radial. That sounded very realistic in flight, but was too 'clattery' (mechanical noise) at low speed and tickover.

The Kolms are lovely engines but I would not put 'realistic sound' as one of their merits. Even the Rans light aircraft did not sound 'correct'.

Last edited by Mark Powell; 11-16-2017 at 02:43 AM.
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Old 11-16-2017, 02:41 AM
  #29  
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Originally Posted by Mark Powell View Post
Actually I think that up to about '120' size (20 cc) a four-stroke single sounds more realistic. Because the number of firing strokes per second, thus the frequency, over its operational RPM range is closer (but slightly lower) to the frequency of a Merlin/Griffon over its operational RPM range.

But as the RPM decreases with size a four-stroke flat twin, which always has evenly spaced firing strokes is better than a single at larger sizes. Or a '360 degree' in-line twin (think 1960's British motorcycles) where the two pistons go up and down together but fire alternately, so again give evenly spaced firing strokes.

Four-stroke triples can't have even firing strokes so their sound frequency varies in an unrealistic 'rhythmic' manner, which explains their uneven (and thus unrealistic sounding) tickover/low speed operation and overall their sound frequency is too high.

A guy at our model site used to fly a Hawker Sea Fury with a 7 cylinder 250 cc Moki radial. That sounded very realistic in flight, but was too 'clattery' (mechanical noise) at low speed and tickover.

The Kolms are lovely engines but I would not put 'realistic sound' as one of their merits.
Realistic Sound maybe not... but cool Sound :-)

My Hellcat has a Flat twin, check out the Video and tell me what you think. link is in my signature.

tom
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Old 11-16-2017, 04:16 AM
  #30  
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Originally Posted by Ixtrim View Post
Realistic Sound maybe not... but cool Sound :-)

My Hellcat has a Flat twin, check out the Video and tell me what you think. link is in my signature.

tom
That's very good - unlike the three cylinder engines the sound is not too high-pitched. And you are flying it very realistically too.

In the UK the Hellcat is rare as a model. It would make a nice change from all the Spitfires and Sea Furys we build
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Old 11-16-2017, 10:22 PM
  #31  
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Originally Posted by Mark Powell View Post
That's very good - unlike the three cylinder engines the sound is not too high-pitched. And you are flying it very realistically too.

In the UK the Hellcat is rare as a model. It would make a nice change from all the Spitfires and Sea Furys we build
thanks Mark!

Anyone else with a kolm-powered Plane here ?

Meanwhile i will Show you some Installation photos. think most of them i builded :-)
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Old 11-30-2017, 08:29 AM
  #32  
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Kolm Engine Tuning Made Simple...

I know that there are a lot of modelers out there with a lot of experience and some of this information may be redundant.

I have four Kolm engines and they all run flawlessly. For those struggling with Kolm engine tuning I hope this will help.

Kolm Engine Tuning Made Simple

The first thing to check after your engine install is for all of your carburetors to be in line via the linkage as it comes from the factory. This is a very important step that will save you a lot of time and frustration later. The carburetors being off can, and will, cause problems during the tuning process. Each carburetor should match from closed all the way to full throttle.
On your first attempt at starting the engine you want your needle settings to be L1 H1.5 (low needle setting) 1 turn out from the stop and the H (high needle setting) 1 ½ turns out from stop. When setting your needles back to the stop position be careful not to tighten them too tight at the closed position as you can damage the needle valve and seat on the Walbro carburetor. Just lightly closed is good. Remember counter clockwise richens / opens and clockwise leans / closes.
Tuning
If you open the throttle fairly quickly and the engine dies, the Low (L) mixture is too lean. To richen it, turn the (L) needles counter clockwise about 1/8th of a turn on all carburetors and try again. This may take several attempts: turn the low (L) mixture screw counter clockwise 1/8th turn each time.
If you go past the ideal setting when richening the Low (L) mixture when you increase the throttle smoothly the engine will not die but start to sound dirty or slightly rough running on the way up. If this is the case lean the low (L) needle ever so slightly ( 1/32nd or 1/16th ) until the engine performs as you want it.
The Kolm engine, like any engine, will be tuning upwards of 1000 rpm’s faster while flying and will be under less of a load. If at full throttle while flying, the engine sounds slightly dirty land and richen the (H) high needle valve by turning counter clockwise about 1/16th of a turn until the dirty sound stops. You should never have to richen the high (H) side more than 1 3/4 turns out.
Safety check. Some people are and some are not comfortable with this, but before you fly you should have two or three people lift the aircraft off the ground while running. You should then transition from idle to full throttle and have the people tilt the aircraft almost vertical to ensure that the engine maintains constant a PRM. If the engine dies this means that the high (H) side is definitely too lean and you need to richen the high (H) side. Start with 1 /16th of a turn.


*Remember when you take your aircraft to different parts of the country atmospheric conditions and altitude may have changed and you may have to re- tune*
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Old 01-28-2018, 10:46 PM
  #33  
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Good Morning:-)

had some testflights with the new BX250 yesterday. small video will follow!
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Old 01-29-2018, 10:23 PM
  #34  
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Here is a short Video :


Tom
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Old 01-30-2018, 07:25 AM
  #35  
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Hi Tom,

After testing, what air frame do you plan to put the BX250 in?
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Old 01-30-2018, 09:18 AM
  #36  
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Hm.
Cant say exactly at the moment. We have a 60% challenger where the Motor will fit perfekt. But there is also a 310-4 which needs a new place to work.

We will see
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Old 02-12-2018, 10:37 PM
  #37  
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Good morning!

i finished the engine installation on Voodoo... some small things to do before rll-out:
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Old 02-13-2018, 04:42 AM
  #38  
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Looks great Tom. I am looking forward to seeing the video of the Voodoo flying. I was curious, in the picture is that small bottle in front of the cowl by the support bracket tied to the engine vent to capture oil residue?

Rob
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Old 02-13-2018, 11:27 AM
  #39  
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Correct. Collects the outcoming oil from the crankcase.
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Old 02-13-2018, 06:23 PM
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Default Hempel 50% Pitts Kolm BX240

Tom Voodoo looks amazing. I also can't wait to see the maiden flight.Here are some Photos of my BX240 installation in the Hempel Pitts which you maidened for me. I have made some small modifications to the install and will add the photos.Some of the photos are oriented the wrong way. No matter what I tried I could not make them straight.
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Old 02-17-2018, 07:54 AM
  #41  
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I'm getting ready to install fuel tank for my Kolm IL-230. I wanted to ask a question on tank size for the engine. Others felt a 1500cc was good, I'm new with Kolm and wanted to get others insight. Do you think the 50oz (1500cc) is too much, or would a 32 oz (950cc) be right. I do fly a little hard and would like to get 8-10 minutes flight max. really no need for more than 10 minutes. Would a 32oz (950cc) give enough reserve fuel?
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Old 02-17-2018, 09:22 AM
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Originally Posted by rbgetz View Post
I'm getting ready to install fuel tank for my Kolm IL-230. I wanted to ask a question on tank size for the engine. Others felt a 1500cc was good, I'm new with Kolm and wanted to get others insight. Do you think the 50oz (1500cc) is too much, or would a 32 oz (950cc) be right. I do fly a little hard and would like to get 8-10 minutes flight max. really no need for more than 10 minutes. Would a 32oz (950cc) give enough reserve fuel?

Yes, a 950cc (32oz) is plenty for 10 minutes. I have a 32 oz in my Pitts and have half a tank left after 8 minutes.
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Old 02-18-2018, 07:44 AM
  #43  
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I agree with Simon. If 8 min are enough for you, 1000cc will be enough. I installed 750 ml on Voodoo for my Il150.

Tom
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Old 03-02-2018, 10:18 AM
  #44  
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Hello Tom,
Carb mod's are complete, ready for the test stand.
Thank you
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Old 03-03-2018, 09:37 PM
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Looks good ! Will work for sure. Same setup a I had on my bf109. Take care that the carbs are 💯 % synchronized. please keep us up to date !
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Old 03-03-2018, 09:43 PM
  #46  
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Voodoo I coming up better and better.
Installed the 4blade prop these days.
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Old 04-10-2018, 11:08 PM
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Had my Mustang out for its initial ground tests today and found out that after sitting for a while the engine needs alot of priming to get it going, this is quite normal as thngs dry up and tnd to stick when not used for a while.. but got it running eventually and testing some different prop pitch settings... I will be using about 16 inch pitch in this ramoser 26.6 inch 4 blade prop to get at least 4500 static on the ground..should give me around 5000 in the air..

now just to tidy up some loose ends and its getting closer to maiden....just in time for flying season

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Old 04-11-2018, 01:11 AM
  #48  
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awesome!
you will get much more RPM in flight. mine is 4900 on ground. going up to 6000+ in flight. can´t wait to see a video!!

Tom
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Old 04-11-2018, 06:30 AM
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Hey Tom,
just wondering where you got your pilot figure for your Voodoo? I have been looking for one to put in my CARF Galloping Ghost that is the right size. Thanks. Jon
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Old 04-11-2018, 07:42 AM
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Hey Jon, I'm looking for the same thing. I just reached out last week to these guys at Benchmark RC. He's making me a bust of a pilot for my Ghost. They'll make any size. I haven't received one yet, but very reasonably priced. I'd like to hear what Tom says as well, but as soon as I get it, I'll share a photo. Rob

https://mhartfab.wixsite.com/benchmark-rc/all-pilots
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