I know this is an extremely generic/probably unanswerable question but here it goes:

My only giant scale is a H9 Yak 54 w/ a DLE 55 on a Xoar 23x8. I've always wondered how fast it is at full throttle, straight and level. I know it's not a speed plane, nor do I really care how fast it is just something I've been curious about.

Also what about 150-200cc 3D/IMAC planes? It's tough to judge when the airframes get bigger/farther away.

And no, my next question is not going to be how much do they cost or how high can they go...

I would guess around 70mph is about average?..........?

That's kind of what I was thinking, seems like 70ish is about accurate.

My Aeroworks Yak 54 with a DA 50 and a Vess 22B was clocked at 85 mph. A friend has a small radar gun and we were checking different airframes. My 30cc MSX-R with an an 18 x 8 was clocked at 106 mph. A friends AW 85 cc Yak with a Mejlik Carbon prop went 108 mph.

It all depends on the airframe/engine/prop combination and the day (cool or hot weather)

I have flown some planes with a test model of the spektrum telemetry unit and a dx18 and 70mph straight and level is about right for a 50cc. 35-40% planes easily exceed 100mph straight and level set up for 3d. With higher pitch props they are faster of course. The bigger planes can appear slower but are actually travelling quite a bit faster.

I have a House of Balsa FW190 on an e-flight 480 3s system and does right at 100mph,clocked. And I use it to gauge against other planes. Was told by the big warbird guys it just looks fast cause it is small. Then I went up and got in formation with them and found I was actually a little faster than they were. Yeh just looks fast.

There are some problems with using hand held "lidar" to clock rc planes so I would take those numbers with a grain of salt. They can be manipulated by the angle the plane is flying at and also if the plane is not traveling in a straight line(zig zag or up and down)A speedo that is actually inside the plane is going to be more consistant.

Originally Posted by husker

There are some problems with using hand held "lidar" to clock rc planes so I would take those numbers with a grain of salt. They can be manipulated by the angle the plane is flying at and also if the plane is not traveling in a straight line(zig zag or up and down)A speedo that is actually inside the plane is going to be more consistant.

I agree with what you've stated. When we did the clockings, we made passes at no more that 10 to 15 feet above the ground, straight and level and made repeated runs to back up the data........even with all that said, there is still room for error.

Originally Posted by husker

There are some problems with using hand held "lidar" to clock rc planes so I would take those numbers with a grain of salt. They can be manipulated by the angle the plane is flying at and also if the plane is not traveling in a straight line(zig zag or up and down)A speedo that is actually inside the plane is going to be more consistant.

Yes you are correct so my numbers are an average of about 25 fly bys. Don't understand why my guy kept moving out of my way?

Originally Posted by vmceachern

Yes you are correct so my numbers are an average of about 25 fly bys. Don't understand why my guy kept moving out of my way?

Exactly.....The guy taking the readings always stood behind the pilot .......no faith, I guess. It was still fun to get an idea of what speeds we were approaching .

Originally Posted by vmceachern

Yes you are correct so my numbers are an average of about 25 fly bys. Don't understand why my guy kept moving out of my way?

I'm not saying you are wrong...your numbers seem pretty close to what I have observed as well.

Some turbine guys here fly at a full scale airport in a small town nearby and they had a local sheriff/friend park his car on the runway as they did some fast passes right over it...sounded like a good idea at the time.

Another time at our field a guy brought a handheld lidar and wanted to clock some planes...he happened to be in a electric wheelchair...Luckily after the first attempt he decided it was a bad idea.

My XFC race plane turns ~140 mph straight and level at our local field over a couple hundred feet with timed runs.

My 30 inch foamy was clocked at 32 degrees BTDC with a timing light. It has a Boss 426 flathead Windsor Hemi inline 6 radial outrunner wedge.

Honest Officer, I wasn't speeding, and you couldn't know because you didn't average 25 runs and measure the cosine of the line of sight and and I was changing lanes and ....

Here, sign your ticket.

Originally Posted by CatalinaWOW

Honest Officer, I wasn't speeding, and you couldn't know because you didn't average 25 runs and measure the cosine of the line of sight and and I was changing lanes and ....

Here, sign your ticket.

Exactly!