MDS F2A 2.5cc
01-27-2015, 06:08 AM
#51
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You CAN increase the diam of aluminum/silicon piston by heating it to high temp. Then you have to drop it in very high heat state to cold water, prefarably salt water. It will "freeze" in expanded state. I give you here another hint on cold/hot massge: it is about tuned pipes or spun exhaust mufflers. If you have bad dent, don`t put any hard object in it to bend the dent out. Just fill with water almost full. close then the ends with paper towel plug and put in a freezer. When water becomes ice.it expands and the dent pops out, nicely and smoothly, without any bad marks. Then just polish it with aluminum polish and yo can sell the pipe as almost as new...
01-27-2015, 11:59 AM
#53
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As a trumpet player on the side (well, sitting or standing usually), I have watched a few "how do they make that?" videos showing thin wall brass tubing being formed around tight corners with a core of ice. Pretty cool technique, not exactly new either. Works for small diameter tubing.
01-27-2015, 01:13 PM
#55
I put this retro vintage muffler together with silver solder and a torch. I have a lil ding I need out then I may take it in to get chromed.
Made for a 15 size engine.
Made for a 15 size engine.
Last edited by Pond Skipper; 01-27-2015 at 06:26 PM.
01-27-2015, 06:21 PM
#57
Thank you CP, technically It has three header pipes to a muffler! 
The stinger was cut a tad long to adjust sound if all goes well I plan to knock off close to half.
The stinger was cut a tad long to adjust sound if all goes well I plan to knock off close to half.
Last edited by Pond Skipper; 01-27-2015 at 06:43 PM.
01-27-2015, 07:43 PM
#58
01-27-2015, 09:15 PM
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Real cool one!!My hint: make three plates between the engine and muffler with one hole only to choose the amount of "purr: Different sound with each different hole configuration !!!
01-27-2015, 09:43 PM
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Go all the way, make it a servo adjustable slide valve. You could accomplish the same thing with an old used cornet silver soldered to an exhaust header, and a servo on each valve. Might want to add a bilabial valve in there, you can go up the harmonic series as the throttle advances. There was an old raspberry type muffler wasn't there once?
01-28-2015, 01:51 AM
#61
Good idea's!!!
I should have went with 4 different size headers with butterfly valves free flopping inside the muffler tube to imitate a 4cyl sound. Steam punk would work lol would have to nix the chrome idea to keep it rustic. The engine makes good power the engineer worked for OS and took his years of efforts into the Magnum line.
I should have went with 4 different size headers with butterfly valves free flopping inside the muffler tube to imitate a 4cyl sound. Steam punk would work lol would have to nix the chrome idea to keep it rustic. The engine makes good power the engineer worked for OS and took his years of efforts into the Magnum line.
01-28-2015, 02:13 PM
#62
I have a whistle that looks like a good attempt at a muffler. I held it on, and it seemed no louder. It wasn't quieter, but it wasn't sealed either. It didn't seem like a great idea at the time. My Supertiger .75 muffler still has the dents in after freezing. So sad. I have a header and pipe for it, but was hoping to make this one nicer looking.
01-28-2015, 03:06 PM
#63
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For a pipe dent, I'd go see a guy who fixes brass instruments for schools - they are great at getting inside small diameter soft metal tubes and making them look half decent again. Trumpet lead pipes are only about .453" ID and they fix those. Just a thought.
01-28-2015, 06:43 PM
#64
Yea thinking I need to chrome the brass was to help add some ding resistance. The silver solder will handle the heat with ease on the .15 so who know was fun to make all the same.
ASpeed bummer it didn't work! Another trick heat up the dent area then spray with a air can for PC it come out coooold. The trick has had some successes depending on the shape of the ding.
ASpeed bummer it didn't work! Another trick heat up the dent area then spray with a air can for PC it come out coooold. The trick has had some successes depending on the shape of the ding.
01-28-2015, 07:23 PM
#66
If the muffler was firmly capped off on the ends with solid plates and tie wire to help the ice build more pressure, then that might work.
If there is a crease involved with the dent, then the aluminum would need to have that spot annealed.
I've got no actual experience doing any of this, but my advice is priced accordingly.
If there is a crease involved with the dent, then the aluminum would need to have that spot annealed.
I've got no actual experience doing any of this, but my advice is priced accordingly.
01-29-2015, 08:27 AM
#67
I could bend some 3/8" rod and ping it from the inside too, but it isn't important. Basic body work. I had heard at one time, that a grease gun can pump up a piece of aluminum tubing to make a pipe too, at least for a 1/2A size.
01-29-2015, 09:57 AM
#68
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Try a pressure washer:
https://www.youtube.com/watch?v=llhcATrmsBg
https://www.youtube.com/watch?v=bCsg5pQimWI
https://www.youtube.com/watch?v=llhcATrmsBg
https://www.youtube.com/watch?v=bCsg5pQimWI
01-29-2015, 11:38 AM
#70
Geez, now I lost half an afternoon watching youtube videos on getting dents out and hydroforming motorcycle exhausts. Interesting though. I actually felt like working on a plane for a change.
01-29-2015, 02:53 PM
#71
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Hi, I live in Helsinki/Finland.. That`s 150 kilometres to St Petersburg. We have , over the years had hundreds russian /soviet engines carried over here, especially after the fall of Soviet CCCP state. The engine in question is a product of "Sovied army aero club" produced in THOUSANDS. In Soviet time these were distribute from the central organization all over the russian state to various youth clubs. Every young member could get one if he wanted. In Baltic countries, especially guys have them lying around by hundreds, because they could, via various conections, get in their hands "real stuff" that means Rossis, Novarossis, Irvine 15 etc. There is really NO COMPARISON to them and the. MDS
A hot tip is that both this engine and the TRAXXAS 15 car engine are almost carbon copies internally to Rossi mark II. You can get very good P/C , rod and various other parts just to ordering them from your hobby shop. Just take the parts of MDS with you and measure you have the right version of Traxxas 15. But still, I just bid 2ea NOVAROSSI 15 Aero Speed engines in Ebay for F2A treiner use for about 150 dollar total (less hipping) I would use the MDS spinner assy, the pipe and the pipe silicon joint ring and simply toss everything else. Just not worth trying to figure it out, The crank is very badly finished, also tempering absolutely too soft-wears out fast. Most of the bearings rough, rodsimply too soft material, will break... The compression is way off, you have to machine the head to make the engine run near it`s pek. On top of everything, the timing is very high resonane timing so you end up having reasonable power in the region of 25.000- 35.000 rpm. Are you really going to have an engine/model combo in this rpm region and how are you planning to gt there without whiping the model very hard ? Toss it an use whatever else. ...
A hot tip is that both this engine and the TRAXXAS 15 car engine are almost carbon copies internally to Rossi mark II. You can get very good P/C , rod and various other parts just to ordering them from your hobby shop. Just take the parts of MDS with you and measure you have the right version of Traxxas 15. But still, I just bid 2ea NOVAROSSI 15 Aero Speed engines in Ebay for F2A treiner use for about 150 dollar total (less hipping) I would use the MDS spinner assy, the pipe and the pipe silicon joint ring and simply toss everything else. Just not worth trying to figure it out, The crank is very badly finished, also tempering absolutely too soft-wears out fast. Most of the bearings rough, rodsimply too soft material, will break... The compression is way off, you have to machine the head to make the engine run near it`s pek. On top of everything, the timing is very high resonane timing so you end up having reasonable power in the region of 25.000- 35.000 rpm. Are you really going to have an engine/model combo in this rpm region and how are you planning to gt there without whiping the model very hard ? Toss it an use whatever else. ...
ChrisM
'ffkiwi'
06-05-2015, 04:35 PM
#73
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Tonight I ran the MDS with a slightly older Profi F2A pipe with pressure tap, Hayes 3oz tank, CF bench prop. I expected to have to fiddle but it fired up immediately, needled easily - lots more pressure from this pipe - and staged easily. I had more needle to go but stopped at 30,500 rpm. What a sweet sound. The new and repaired rod seems to be holding up fine. Engine was not over hot and feels great after cooldown.
Needle behavior was smooth and predictable, the pipe pressure did a great job adjusting the fuel flow in step with rpm, no frantic needle cranking. This however is not as hyperactively timed an engine as more modern F2A engines, so I may yet see why pipe pressure seemed to be out of favor with the speed junkies I spoke to.
Might be time to finish the 24" SWR delta.
Needle behavior was smooth and predictable, the pipe pressure did a great job adjusting the fuel flow in step with rpm, no frantic needle cranking. This however is not as hyperactively timed an engine as more modern F2A engines, so I may yet see why pipe pressure seemed to be out of favor with the speed junkies I spoke to.
Might be time to finish the 24" SWR delta.
Last edited by MJD; 06-05-2015 at 04:41 PM.
06-05-2015, 08:33 PM
#74
It sounds like the potential is there, plus great parts support
Pipe pressure is absolutely dependent on the silicone pipe seal..so engine damage will result if the seal burps. There's other ways to roast engines though, so if pipe pressure works well...then great..!
The Nelson FAI .40 uses pipe pressure because it was found that it could keep up with fuel demand and a 13mm venturi. Venturi size is a tuning tool too..it goes hand in hand with the pressure source of your choosing.
Pipe pressure is absolutely dependent on the silicone pipe seal..so engine damage will result if the seal burps. There's other ways to roast engines though, so if pipe pressure works well...then great..!
The Nelson FAI .40 uses pipe pressure because it was found that it could keep up with fuel demand and a 13mm venturi. Venturi size is a tuning tool too..it goes hand in hand with the pressure source of your choosing.
06-05-2015, 09:49 PM
#75
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The seal is tight so far. I opened the stinger to 4.65mm from 4.2mm. This was recommended for the longer runs to reduce heat buildup a bit. Shortened a 6/32 pressure fitting, "tapped" a hole through the thin wall just ahead of the weld, and JB Welded the fitting in. An hour and a half in the oven at 175 and voila.
Prop is a 5.75" diameter Mike Hazel bench prop - patterned after a 5-3/4" long piece of wood with maybe a 3/8" x 3/4" cross section, and a crude diamond airfoil carved in, corners rounded. Sort of a heavy cooling fan with enough drag and crude "pitch" to load the engine lightly and blow some air over it, let it stage easily on the bench, but keep it under control.
10% Omega with a few % castor. Head button is the 10% "nitro" head I got with the Profi.
Prop is a 5.75" diameter Mike Hazel bench prop - patterned after a 5-3/4" long piece of wood with maybe a 3/8" x 3/4" cross section, and a crude diamond airfoil carved in, corners rounded. Sort of a heavy cooling fan with enough drag and crude "pitch" to load the engine lightly and blow some air over it, let it stage easily on the bench, but keep it under control.
10% Omega with a few % castor. Head button is the 10% "nitro" head I got with the Profi.
