RE: Experienced with the TWM P-51 GS?
 

Apparently the low top end RPM was just because of the morning moisture and the new engine. Now that it's dry and with a few more tanks of gas through it, it will hit 8160.

This engine is definitely going in my plane.

I made a recording. If it is decent, I will upload it.

RE: Experienced with the TWM P-51 GS?
 

The video is at [link]http://www.youtube.com/watch?v=UIbj7iwzaEQ[/link]

RE: Experienced with the TWM P-51 GS?
 

Here are the pictures from this test stand.

RE: Experienced with the TWM P-51 GS?
 

I sanded the "log" and put clear polyurethane on it. I made a 1/4" plywood plate to hold the ignition, ignition battery, switch, and mini-tachometer. The plate is also to hold the tuned pipe or canister mufflers when I test those.

There were several reasons for making this test stand. Portability. Dampening of vibration. Ability to support tuned pipes and canisters. These were the primary reasons. I also wanted to have plans that other people can use for making safe and effective test stands. I will be publishing the plans for this test stand base and I may even sell them.

I have a lot of web work to do today, so I doubt if I will get to test the GT33 with the tuned pipe. But I will get to it in the next couple of days.

That is my primary goal for this thread. The header that came with the [link=http://www.horizonhobby.com/products/silencer-system-complete-26gt-gt2-gx-EVO30944266E]Tuned Silencer[/link] is not an exact fit for the GT33, but I was able to file the bolt holes and make it fit. The pipe is also for a 26cc engine and not the 35cc pipe and may not be the best pipe. But the header that comes with the 35 pipe definitely won't work. Macs has a header that will soon be available for the DLE-30 that will be an exact fit for the GT33.

But my test stand is now ready and I will be able to do some good testing.

RE: Experienced with the TWM P-51 GS?
 

I received my Scratch and Dent P-51 Double Trouble on Friday. The flaws are minimal as they were on Barry's, but the planes aren't perfect. AirBorne has some more and at $200 plus shipping they are a deal. The main thing that is wrong is that some of the fiberglass parts that are covered are mildly distorted like the stab tips and the fuselage wing fillets. I posted a picture of the worst stab piece so you can see what mine looks like.

I got a second plane because I'm committed to P-51 Giant Scale Racing. James Barr has had some issues with his plane, but there are enough people that have had success with 30cc-35cc engines on them that I'm not worried. Keep an eye on the [link=http://www.abmshowcase.com/the_world_models/warbird/p51gs/video/default.aspx]P-51 Mustang G.S. - Video[/link] page. I'm just so busy and I'm taking my time on mine that I will get mine in the air when the time is right. I'm doing my yellow P-51 as BARDAHL Miss or BARDAHL II with the streamlined canopy.

Like I've been messing with the Melody MLD-35 until I got the O.S. GT-33. I had ordered parts for it including the Rcexl ignition. I ran the MLD-35 with the new ignition today and the engine is now a sweet running piece of machinery. Before it was getting up to 8130 rpm with the Xoar 18x8. Now it is getting up to 8250 and running as smooth as can be with no misfiring whatsoever. Idling down to 1800 with no problem. Shaking a little at that number, but idling smoothly at 2100. I'm not sure if I will put the MLD-35 or a DLE-30 in my Double Trouble.

I ran the O.S. GT-33 with the tuned pipe on my new test stand. I really like the test stand. It absorbs vibration and has just the right amount of flex in it. And the tuned pipe, even though it is the pipe for 26cc engines worked very well. It brought the engine up from 8160 to 8750 (with the Xoar 18x8) and is quieter. I think the 35cc pipe may do better and I look forward to trying the Xoar 18x10 to see how it works.

Sure, we could just put 55cc engines on the planes. But then they would get faster and faster. I want to push the limits of the speed creep early on. And I want to keep the speeds down to approximately 120-130 mph if possible.

RE: Experienced with the TWM P-51 GS?
 

Don are you going to try some Nitro in it ?  5% or even 10% or some 112 Oct racing gas?

RE: Experienced with the TWM P-51 GS?
 

I would rather have you burn up your motor than burn up mine. But, it is all good!!http://www.rcuniverse.com/forum/js/f...eeth_smile.gif

RE: Experienced with the TWM P-51 GS?
 

unless you have 16 to 1 compression, 112 octane gas will create less power. Nitro in a gas motor, did that too, burned the hell out of the piston and rings.

RE: Experienced with the TWM P-51 GS?
 

Well Skully, there are a lot of variables that have to be dealt wit. Main Jet size especially and if it is a cast piston no more than 10% nitro. Might even consider a couple of more % oil also.So, tell us what you did to burn up your motor? IMWTK!!

RE: Experienced with the TWM P-51 GS?
 

Sorry about the double post. I will say I am really excited about this new Class of P-51 GS Racing that RCPRO is forming. Skully any of your Texas guys interested??

RE: Experienced with the TWM P-51 GS?
 

Funny you should ask.

Yesterday I got two new 2.5 gallon Blitz containers from Lowes and I stopped by Ironhorse Motorcycles in Monroe and got 1 gallon of Sunoco Racing Fuel in each container. I mixed 4.5 ounces of Pennzoil Air Cooled oil for a 30:1 mix in one jug and ran it in the MLD-35. The people at the parts counter who filled the jugs couldn't tell me the octane rating. They said it was 114 or 118. They said they knew it was over 110. It was purple before I added the blue oil.

It seemed to add about 50-100 rpm to the MLD-35. It ran hotter and I did not try it in the GT-33. I may try later.

I had to open up the needles. Both the idle and the high speed to get it to run. I guess it is burning more fuel.

The MLD-35 is a useful mule for tinkering. The video with the Rcexl is at [link=http://www.youtube.com/watch?v=x_uemK5PGNg]MLD-35cc Gas Engine with Rcexl Ignition[/link]. That was with the premium 93 octane. It did actually run smoother on the racing fuel. The heat concerned me though.

David McAllister at Macs Pipes said he can make me a header for a tuned pipe on the MLD-35 using a Quadra 52 plate.

But he is going to have a header for the DLE-30 / GT33 soon and I may get a DLE-30 to put in my Double Trouble.

RE: Experienced with the TWM P-51 GS?
 

Not to be a smart ass,,

"Octane rating or octane number is a standard measure of the performance of a motor or aviation fuel. The higher the octane number, the more compression the fuel can withstand before detonating. In broad terms, fuels with a higher octane rating are used in high-compression engines that generally have higher performance. In contrast, fuels with low octane numbers (but high cetane numbers) are ideal for diesel engines. Use of gasolines with low octane numbers may lead to the problem of engine knocking."


http://en.wikipedia.org/wiki/Octane_rating

RE: Experienced with the TWM P-51 GS?
 

Yes jets, and type of piston play a role, AND we were dumping 1/2A fuel (25%) into a small 4 stroke motorcycle engine. It ran great for an hour or so, then it went South real fast.

Now for some fun.. What does Nitro do?

As for the GS P-51, I have no idea, I know we have some GS guys here in Texas, but never heard anything about P-51's.

RE: Experienced with the TWM P-51 GS?
 

Skully,

We are forming a new racing class referred to as P51GSR. You can see the rules at [link]http://www.rcpro.org/content/rcpro/p51gs/rules/default.aspx[/link] and check out the special deal on planes at [link=http://www.rcpro.org/content/rcpro/p51gs/default.aspx]RCPRO P-51 Giant Scale Racing[/link]. You can see more about the planes at [link=http://www.abmshowcase.com/the_world_models/warbird/p51gs/default.aspx]P-51 Mustang G.S.[/link].

AirBorne Models has some planes with minor flaws for sale as "Scratch and Dent" for $200 plus shipping. Barry and I got one each.

RE: Experienced with the TWM P-51 GS?
 

Here are pictures of the fuel. The first is the 93 octane with the Pennzoil. The second is the Sunoco Racing Fuel with the same ratio of Pennzoil.

RE: Experienced with the TWM P-51 GS?
 

Barry,

You haven't mentioned getting a fuel jug yet. I have a recommendation. Use the Blitz 2.5 gallon jugs you can get from Lowes. And use the the [link=http://www.pspmfg.com/FuelJugCap.html]Fuel Jug Cap in RED for the Blitz gasoline jug.[/link] from PSP. It is worth the price. I messed with a homemade top and it was a pain. The [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXJGS5&P=ML]Dubro Kwik Fill Fuel Pump[/link] comes with a nice little chain that you can put around the handle and a clip to attach the pump to the jug. It is a nice easy setup. You can detach the pump from the chain easily. It does come with tank fittings if you want to make your own top.

RE: Experienced with the TWM P-51 GS?
 

Don, I have a gas can on order from Hodges.  It will probably be painful compared to your really sharp looking tank but, That's the way it goes sometimes.

RE: Experienced with the TWM P-51 GS?
 

I'm putting Robart 701RS retracts in the BARDAHL Miss and I fitted one today. Had to cut 1" off the RoboStrut.

RE: Experienced with the TWM P-51 GS?
 

Great looking installation.  The Robart's are very nice.  <div>
</div><div>After I get stock gear set up with the servos I may get the Robart struts to help absorb the landing shocks.  Of course it I could guarantee a greaser every time I landed it would be an issue.:D </div>

RE: Experienced with the TWM P-51 GS?
 

Well it is my first experience with the Robart retracts and RoboStruts. So it will be interesting to say the least.

This whole P-51 GS thing is a big learning experience. I'm trying to take away and document as much as I can.

I made a video of the retract system and my initial install and it is at [link]http://www.youtube.com/watch?v=_2aFcKU-GFk[/link]

This is the [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXNCY1&P=7]Robart 701RS 85 Degree Spring Down RoboStrut Ready[/link] with the [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXES99&P=7]Robart Left Hand RoboStrut 3 3/4-4" Wheel 7/16"[/link] and [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXET00&P=7]Robart Right Hand RoboStrut 3 3/4-4" Wheel 7/16"[/link].

RE: Experienced with the TWM P-51 GS?
 

using the race gas will cause more heat...one way to handle that is add more timing, as race gas burns slower, lack of timing allows fuel to exit unburnt. removing measuring base cylinder gasket and substituting a thinner gasket will help as well. a colder plug can be added when you advance timing

RE: Experienced with the TWM P-51 GS?
 

you are better off just running the engines as they were designed on "pump gas". Your wasting money on the "race fuel" Do you have a "race engine" no you dont you have a stock normal engine. Running the "race fuel" in a stock engine will cause more carbon build up in the exhaust port and muffler and over time reduce your engines performance. Now you can buy some "race gas" in a much lower 92-93 octane rating but its still a higher price and not much gain.

Adding or removing shims is no longer a stock engine correct??? so are mods allowed in this class?

RE: Experienced with the TWM P-51 GS?
 

From [link]http://www.rcpro.org/content/rcpro/p51gs/rules/default.aspx[/link]

Engines will be gasoline burning 2 cycle 38cc displacement or less with reed valve induction.
Engines must have a spark plug and no glow plug conversions are allowed.
Engines may be modified except for addition of supercharging or turbocharging.
Engines may have aftermarket mufflers, tuned pipes, or velocity stacks.
Any size of prop may be used and props may be modified.
Any type of fuel system may be used.
Contestants must provide their own fuel which may only contain gasoline and oil.

RE: Experienced with the TWM P-51 GS?
 

Thanks for the insight Lorin.

I didn't think about the timing being a factor in the heat.

I went out to the garage where the engines are still on the stands and measured the Rcexl sensor on the MLD-35. It has at least 3/32"of movement available. I had tried to center the sensor quickly when I put it on the engine. I may have had it advanced some or retarded some.

By my calculations it has at least 8 degrees of adjustment without modifying the bracket.

RE: Experienced with the TWM P-51 GS?
 

I ran the MLD-35 on Saturday 6-30 and tried playing with the timing. I did not run the racing fuel as it was over 100 degrees and I was just too hot. I found that advancing the timing really changes the way the engine runs. With the timing advanced to the limits of the normal slots, the engine ran much better and the performance increased significantly. It got up to 8390 to 8400 from where it had been at 8250. When I brought the timing back to being centered on the range, it came back down to 8200-8250 and did not run as smoothly.

I needed to run the GT33 with the tuned pipe, which I did and I recorded video which will be posted shortly.

If I get time, I will put the MLD-35 back on the test stand and try the racing fuel with the advanced timing. I found out that the racing fuel is 114 octane. If I do test the racing fuel, I will do it with the Pennzoil and with a synthetic, and I will do it methodically with timing changes as the interplay seems significant and I don't want to just be shooting in the dark. Right now I have a lot of airplane prep and flying I need to do, so experimenting to get a limit bit of performance is not the highest on the priority list, but it is fun to play with.