drac1

My Feedback: (4)

Hey Matt,

No not yet. I have the props, but been busy. I hope to get one balanced and try next week when I get home.

riot3d

Matt,

I've been flying with the 21x10.5 PN, a lot of prop for the 185. The engine can handle it but need to throttle up sooner, & be sure to have enough ventilation, especially on a hot day. I may shorten it to a 20.5x10.5 & give that a try.

There's a prototype 21.5x10.5 also.

Adrian

MTK

Hi Adrian, and thanks for the info. Are you saying that you no longer point the nose up, then throttle up like you used to do? That now the model gets slow enough to need throttle up before the corner?

The 20.5x10 PN should be doing a fine job on the 185, on moderate nitro. What exactly are the slightly bigger props supposed to deliver? A slower presentation possibly? Or something else?

riot3d

HI Matt,

My Aiolos is slightly over 5K dry, & weighs more with a full tank of 600cc fuel. In addition, I'm using the same throttle curve for both the 20.5" & 21" prop & believe the 21" is probably better suited for the cdi version. As stated, the motor will handle the prop, but just needed to throttle up slightly earlier in my case. However, I think I will try it again on my Acuracy which only weighs about 4,800 dry

However, I do like the higher pitch, it pulls just like a freight train. They do make a 21x10PN but I felt like I can use a bit more pitch, hence the reason why I wanted to try the 10.5 pitch. After I've a chance to try the 20.5x10.5 I'll report back.

Adrian

rcpattern

My Feedback: (45)

I've had a chance over the last couple of weeks to finally install and play with the ignition in my Galactik. So far very happy. I spent most of the year running straight glow with the 20.5X10, but I'm running the 21X10.5 at about 6750 with a consistent idle of around 1650. I can comfortably fly 2 P-17 sequences on the stock 600cc tank. Throttle response is excellent and very smooth. So far, very happy with the setup.

Arch

drac1

My Feedback: (4)

Less RPM, which would mean less noise would be one benefit.

drac1

My Feedback: (4)

I flew the 21 X 10.5PN this afternoon. In short - Perfect match for the 185cdi. The Valiant is just under 5kg's, so it isn't a light weight model either.

I used the exact same setup as for the 20.5 X 10PN. I didn't even have to adjust the mixtures, which probably means I was still a bit too rich on both.

Idle is a rock steady 1700, which is similar to the 20.5 X 10 but more stable. Throttle trim position is unchanged also. Top RPM was 7300 for the 20.5 X 10. The 21 X 10.5 killed 500 RPM and now sits at 6800. Noise at full throttle is noticeably less which is a result of the reduced revs. It's a much more pleasant throaty roar.

As far as flying, well, it just does it better than the 20.5 X 10. The plane tracks better and requires less throttle stick movement, which means a reduced work load. I pull into a vertical the same as with the 20.5 and feed on the power as usual. There's no need to throttle up earlier. The difference is I stop at around 5/8ths throttle and just leave it there. It doesn't slow down at all, just keeps pulling until it's time to push over or whatever. Throttle control for the figure 9 with 4 point roll up also uses the same technique. Basically set and forget. Down lines are more constant speed as well.

With the 20.5, I had to be more aware of throttle control coming down the back side of loops as the engine rpm would increase noticeably. With the 21 X 10.5 it doesn't do this.

This prop makes really good use of the mid range torque that the cdi produces.

I have a gut feeling that fuel consumption is less also. It's certainly no worse. Really looking forward to getting some more flights with it over the next few days.

apereira

This propeller was tested and the design was adjusted to the 185CDI, almost a year I think, so it should be perfect.

Just wanted to mention the engine reacts depending on the setting, I have my own setting which I really like, others fly leaner, so it is flexible enough to satisfy most users, but comparisons might not necessarily mean a set up is good or bad.

Regards

Alejandro

drac1

My Feedback: (4)

Correct Alejandro, testing went on for around a year and it was designed for the cdi.

A good set up is one that; reduces pilot work load, makes the plane easier to fly, gives constant speed and gives good fuel efficiency. This prop does all that.

I'm now going to order the 21 x 10 PN. From what I've heard it gives better breaking, so will be interesting to try.

apereira

I also think the 21x10 might be a better choice, I think I will try both next week.

Regards

drac1

My Feedback: (4)

It will also be interesting to try both these props on my bipe once it's finished.

riot3d

Have also tried the 21x10 on my non cdi but didn't like it at all, plenty of forward speed but lack the pull. So far, I think the 20.5x10 is the best for the non cdi, but I want to try the 20.5x10.5 as well.

Adrian

drac1

My Feedback: (4)

What RPM did you get with the 21 X 10?

How much nitro are you using?

drac1

My Feedback: (4)

Probably most likely find the 20.5 X 10.5 will lack in vertical as well. The glow doesn't have the mid range torque that the cdi has.

vatechguy3

My Feedback: (11)

any updates?

anyone tried 20% nitro?

or the zero version?

tony

MTK

Interesting Adrian.....The piped OS 33 hauls the 20.5x10.5 prop pretty well at just about 7k. But most importantly is its ability to produce good mid range performance, with very good verticals on an 11 1/2 # plane.

It sounds like about the only subtle difference is downlines. While the two stroke's down line is plenty slow, it sounds faster. The four stroke's downlines not only look slow, they sound slow.

Thanks for posting honest assessments without hyperbole.....

richard_kis

Hello all,
Does anyone have a tip on how to reseal that top plastic check valve (older DZ engines) after it comes loose? Or is the only solution to replace with a new part?
Thanks much,
Richard

apereira

That is a head replacement as it is a press fit , but I remember seeing in groups people securing it with JB Weld.

There’s also a special Loctite used to attach nipples and bearings, maybe that could work?

Regards

drac1

My Feedback: (4)

If it's the black plastic part, need to get a new check valve.
If it's the brass injector, need to get a new head.

Scott

richard_kis

Thank you. I tried to epoxy the check valve again (the previous attempt worked for about 15 flights) until the new valve arrives..
Richard