Dynam C-188

[xviper]

Thanks, Harry. Another confirmation is always nice. 65mm it is. I'm flying mine with the 10.5x8x4 prop from the RocHobby Corsair. I just finished maidening my HobbyKing Tundra with the same prop. It flew great. Hoping the same for Dusty tomorrow.

[Harry]

Xviper, also see my posting #54 above. Spring loading the landing gear.

http://www.hobbysquawk.com/forum/rc-airplanes/propeller-airplanes/1183-dynam-c-188?p=40675#post40675

[Iowa54]

Thanks, Harry. Another confirmation is always nice. 65mm it is. I'm flying mine with the 10.5x8x4 prop from the RocHobby Corsair. I just finished maidening my HobbyKing Tundra with the same prop. It flew great. Hoping the same for Dusty tomorrow.

Let me/us know how that prop set up works and how you attached it, Sounds interesting

[Flygirl]

According to my research, internet and actual, 65mm from the leading edge is the magic number. I also use 2.2A Lipos, all the way forward, Dubro lite 3" wheels which is about 2x the weight of the original wheels, plus 3x 7gr (3x 1/4oz) weights on the nose, to get I slightly nose down balance. (NB: important to check the balance plane upside down with balance points close to the fuselage)

I did test fly the C188 "as is", "out of the box", but it was a struggle. It flew very mushy especially in the turns. I recommend that you thoroughly check the COG balance before flying.

I do not understand why some C188's are in balance without nose weights and some not? Unless the foam density varies or some models have different push rod thickness? I have found postings where some pilots went up as high as 1 1/2 oz on the nose.

Keep us updated!

I'm using the 4s 2500mah battery shoved all the way forward and did not use any nose weight...

[xviper]

Xviper, also see my posting #54 above. Spring loading the landing gear.

http://www.hobbysquawk.com/forum/rc-...0675#post40675

Roger that. I will do something similar to strengthen the strut. I'll fly it first just to see how weak it is.

[Harry]

I'm using the 4s 2500mah battery shoved all the way forward and did not use any nose weight...

That should be ok because the weight difference between 2200 and 2800 is about 66gr. Should more or less even out against the 21/ 28gr on the nose when using the lighter battery.

[xviper]

Let me/us know how that prop set up works and how you attached it, Sounds interesting

Besides the 1 piece 4-blade prop from the Roc Corsair, I needed a thick washer to act as a spacer between the motor face and the back of the spinner base (too close). I FoamTac'd some sandpaper discs on both sides of the washer so there wouldn't be any slippage when torquing the nut down. I'm using the yellow spinner and cone from a HobbyKing Durafly 1100mm P-51 Mustang. The back of the spinner back plate needs to have the 4 ribs ground down slightly so it would sit flush with the washer face. Then the prop goes on, then the stock washer and nut. As for the spinner cone, the only way to secure it was to put a dab of FoamTac into each recess of the backing plate, then I used 4 small strips of Blenderm between each blade to hold the cone in place. I'll post a video showing the prop, spinner and maiden tomorrow.
I flew the Tundra this morning with that prop and it worked extremely well. The plane flew well, with lots of power to even do a prop hang and pull vertically out of it. The sound was also very pleasing. The Tundra flies on 3s, so I suspect Dusty on 4s (lower KV) should be more than comparable.

[xviper]

Here's a pic of "Dusty". I've got it balanced at 65mm. The 2.2, 4s battery is almost centered on the stock velcro, perhaps 1" further aft. Of note is the 4-blade prop and the "non-stock" pilot.

[Harry]

Wow! With that prop it sure looks like a "mean machine".

[xviper]

I just remember "Dusty" from the movie "Planes". They gave him a 4-blader, retracts, tip tanks and wings from a P-51. I'll stop with this.

[Flygirl]

I just remember "Dusty" from the movie "Planes". They gave him a 4-blader, retracts, tip tanks and wings from a P-51. I'll stop with this.

LOL!!!!!!!! You're cracking me up ;) That would be a real Frankenplane!

[xviper]

Finally maidened it today. Perfect conditions - calm, sunny, warm. The 4-blade prop worked well and gave it plenty of punch. I'll have to try the stock prop one of these days just for comparison. Even though all the control surfaces looked level, it needed a lot of DOWN ELE to fly right. I think I need to move the battery further forward. Once trimmed, deploying flaps required virtually no ELE compensation. It just kept going straight. Does rolls, loops and inverted flight very competently.
I've compiled an edited video out of 3 videos taken with 2 different cameras. The first flight was the maiden and trimming flight. Although I've tried to edit out much of the clips where the plane was too far away to see, viewing in "full screen" is better.
PS. Meant to say that I didn't find the stock landing struts to be that weak, considering how lumpy and bumpy our field is.

[Flygirl]

Finally maidened it today. Perfect conditions - calm, sunny, warm. The 4-blade prop worked well and gave it plenty of punch. I'll have to try the stock prop one of these days just for comparison. Even though all the control surfaces looked level, it needed a lot of DOWN ELE to fly right. I think I need to move the battery further forward. Once trimmed, deploying flaps required virtually no ELE compensation. It just kept going straight. Does rolls, loops and inverted flight very competently.
I've compiled an edited video out of 3 videos taken with 2 different cameras. The first flight was the maiden and trimming flight. Although I've tried to edit out much of the clips where the plane was too far away to see, viewing in "full screen" is better.
PS. Meant to say that I didn't find the stock landing struts to be that weak, considering how lumpy and bumpy our field is.

Like it huh? I flew mine this evening after work too. The power was kind of surprising eh? Was for me too.... I'm pretty happy with the plane myself. :)

Vipe, why the one white prop blades?

[xviper]

why the one white prop blades?

I'm not sure. That's the way it comes on that Corsair. I guess the real Reno Racer was like that.

[2FewDaysAtFlyingField]

I'm not sure. That's the way it comes on that Corsair. I guess the real Reno Racer was like that.

The Race 57 Reno Super Corsair had a Prop Strike years ago and borrowed a white prop blade from another racer so it could finish the event. The look stuck and she has had one ever since.

[Flygirl]

The Race 57 Reno Super Corsair had a Prop Strike years ago and borrowed a white prop blade from another racer so it could finish the event. The look stuck and she has had one ever since.

Ha! So mystery solved! Thanks!

[Harry]

.... Even though all the control surfaces looked level, it needed a lot of DOWN ELE to fly right. .....

Nice video viper! I had similar experience with my maiden. Immediate down elevator trim was necessary. That made me re-check my COG more thoroughly which ended up to show tail heavy problem.

[Harry]

Finally got some nice flying weather yesterday and today. Did my final COG testing and with a 2200mAh LiPo (all the way forward), and 28gram (1 oz) weight in the nose, it flies very well.

But,... after about five flights, my landing gear is also loose. Looks like when one tightens the landing gear screws, the foam gets compressed somewhat, the plastic mounting being slightly below the foam level, then later the foam compression relaxing and the wiggling, will work the screws loose again.

Edit to add: After removing my landing gear and modifying the fuselage by glueing a square piece of thin wood to give the landing gear mounting area a more solid base, I couldn't tighten the screws again. End of long story, the nuts stripped! Had to open the foam from the electronics' bay side to replace the nuts. I can see why another member posted that he increased the size of the mounting screws. I can also understand postings where pilots said the the screws are to short. They are probably stripped? This plane really flies like a dream but the landing gear mounting can be an issue. After five reasonably acceptable landings, this should not have happened that easily.

[lupdike47]

I have the Dynam c-188 and can't say it has been trouble free. On the maiden flight it was tail heavy and while this made it difficult to fly on the first outing, I didn't crash it (but came close), but I didn't diagnose it correctly and it caused a crash on the second flight. I repaired it and added weights to the nose and it flew acceptably, but certainly not easily. I have learned you have to land it with some power or it will tip stall. It can also get squirrely in any wind at all. Recently I flew it into some turbulence trying to land it and got blown into a tree next to the runway on final approach. It came down hard on the nose, which broke the foam firewall behind the mounting plate. I repaired this, but when I flew it again, it snap rolled to the right on take-off. I know the nose is not the same as it was when it was new. The cowl no longer clears the back plate on the spinner assembly so I've had to cut out some semi-circles in the front of the cowl to get clearance. I'm thinking the thrust angle could also have been altered in the crash, but don't know what it should be. So if you know the correct angles, please advise. Incidentally, I also tried to get the mounting plate out when I was fixing the firewall but couldn't and in the process stripped the head of one the mounting screws, so now I have no idea how I'm going to get it out if I have to adjust the thrust angle, at least not without cutting off the whole front of the fuselage so that I can get a proper tool onto the stripped screw. Do you have any thoughts or advice? I've had this plane for a couple of years now, so maybe its time to move onto something else.

[xviper]

Any RC aircraft that has been crashed can and usually do exhibit some issues with flying again after repair and from the sounds of it, your crash was significant enough to bend stuff out of alignment and out of shape.. As for the angles, that's going to be hard to give you in terms of degrees, etc. It's different for every plane and hard to measure. For "Dusty" and other similar planes, there should almost always be a little down angle on the motor thrust line and a little to the left (for a standard spinning motor). Looking at plans for scratch built planes, I've seen numbers in the range of up to 3 degrees left and 3 degrees down to make the plane fly OK in a straight line. Dusty is a very floaty plane and can be flown very slowly but therein lies the problem. It can fly so slowly that it is deceiving to the eye and you can go too slow and have it stall. Best to keep the speed up till you get used to it and do your experimenting high up to know just how slow you can go.
On a side note, "Dusty" is not an expensive plane. If it were me, I'd fix it and fly it till you drill it into the ground and then salvage what you can for a future plane. Mine is also about 2 years old and I still enjoy flying it from time to time.