I saw that ages ago when it was posted on Youtube ...
His claim is based on a single shot GPS logger ... it records the HIGHEST speed attained during period switched on. His speeds are OUT OF DIVES speeds and therefore great for chat at the Bar ... but invalid for claims.
He also makes no runs to compensate for wind speed.
Doppler shows a different story to his claims .. it's ages ago when I checked it ...
Even Guinness is questionable in their rules for speed claims ...
I agree but 100mph is 100mph regardless of coming out of dive, downwind heading or whatever. Do these loggers use a pitot tube? Perfect conditions of no wind and a long, straight line level pass are not always possible. To the naked eye, and based on my own edf experience, it sure looked pretty fast. My EF-16 is slow by comparison. In fact, have yet to get any of my edf's over 100. Not even the new 4s Stinger. However, the pusher props like the 800mm Radjet and even the Jpowers Rare Bear on 4S can achieve those kind of speeds. The numbers will always be fudged slightly somewhat, right? Doppler radar has got to be the best measuring tool.
I agree but 100mph is 100mph regardless of coming out of dive, downwind heading or whatever.
In terms of whether model can stand it - yes. In terms of actual speed that model can sustain by own power - no.
Do these loggers use a pitot tube?
Depends which logger you are talking about ... GPS is satellite positioning same as you use for your car navigation / boat navigation etc.
Pitot tube is differential air-pressure. Two pressures are measured and compared ... static pressure and dynamic. The static pressure is bled in at the side of tube (tube is a double tube - one inside other) and the open centre tube faces direct into airflow. This centre tube then experiences an increased pressure due to the model moving fwd.
The comparison also removes compensation calculation for low or high pressure conditions and also temp.
Perfect conditions of no wind and a long, straight line level pass are not always possible. To the naked eye, and based on my own edf experience, it sure looked pretty fast. My EF-16 is slow by comparison. In fact, have yet to get any of my edf's over 100. Not even the new 4s Stinger. However, the pusher props like the 800mm Radjet and even the Jpowers Rare Bear on 4S can achieve those kind of speeds. The numbers will always be fudged slightly somewhat, right?
People love to quote as high as they can get ... hoping that others will not nit-pick !!
Doppler radar has got to be the best measuring tool.
Depends what you want and also how 'safe' you want to be.
Lets look at speed measurement : (Remember true model speed is what the model 'see's' in the airspace it is moving in).
GPS : Measures speed by comparing position change calculations usually over 1 .. 2 or more seconds - on full navigational sets, user can set the averaging to remove the jumps in speed / direction that arise from position jumping around. It has an error in speed that is based on a vertical component ... 3D fixes are needed to compute altitude change ... but often this is in error and speed displayed defaults to level path.
Speed is SoG ... Speed over Ground and is in error for any air movement such as WIND speed and DIRECTION - when considering actual model speed and requires exactly opposite runs to be able to average out to STILLl air speed.
Doppler : this basically gives similar end result to GPS in that it computes ground speed based on the Doppler Shift of sound waves from the model. Two runs have to be made opposing to negate air movement .. wind.
Radar : Uses time calculation of radar signal out and received back ..this being an ongoing send / receive giving ability to calculate speed ... it has same problem as GPS.. Doppler.. in that it measures SoG.
Pitot : This is the ONLY measuring system that ONE RUN without need for second opposite run can actually give accurate air-speed. Reason being that the model is moving within the moving air-mass and knows nothing about wind direction or speed. It see's the air as a mass to pass through.
The TRUE speed of a body through the air - is actually the AIRSPEED. Why ? The propeller or fan or jet or rocket is NOT a wheel creating movement on a fixed terrestrial matter. It is creating the movement within a moving mass of air. A prop that is designed to produce a speed of 100mph will do that ... but to you on the ground in 20mph wind will measure (GPS / Doppler / Radar Gun) as 120mph when flying WITH the wind, and 80mph when flying against the wind ... but model will be still flying at 100mph throughout, which the Pitot system will register as 100mph regardless..
I've tried to put it in simple terms .. My main profession before taking up the Oil Superintendency, was as a ships Navigating Officer.
GPS, Pitot, Doppler are subjects I had to study along with a lot of other stuff !!
(GPS as positional gear ... Pitot as through water speed indicators ... Doppler as docking indicators for large vessels to avoid damaging docks etc. and as speed indicators. Radar of course as can be imagined ... ).
Tested the Sapac T-45 the other day and all I can say is: Calamity ! LOL Stupid me.
I loaded what I thought was a CHL 4S 3300 40C lipo. Ran her down the runway and she just would not rotate. Then, later, as I was packing up, I noticed a 4S laying in the trunk of my car. Yep. I had actually loaded a 3S lipo. Duh !
So, I have not given up hope to get this bird airborne.
But note how close to COG his main wheels are ... when he taxies out at start - she very nearly tips on it's arse on the bumps ... TOO close to CoG for my liking. With that - liable to haul of too early.
I see that many people are running 5S and 6S in them ... that explains the insane speeds people claim on them.
I think it was intended to be a 3S machine but I wonder how anyone can get it airborne on a 3S without throwing it off a cliff. It does have a huge battery cabin though. I will have a 3300mah 4S 40C next time. 50 amp esc installed.
Parked on the ground without battery, she'll stand up on her mains in "wheelie" fashion. Lipo balancing is everything with this plane. I'm good with that.
Why I thought it was kind of a 90's style model? There's no good way to secure the canopy. I trashed their rubber band setup and am using Velcro. The canopy parts needed to be cut to size with the cheapo vacuum formed molded parts. PITA.
One aileron servo and one elevator servo. I jacked up the throws to 120% with the rod clevices attached to the inner most holes on the horns. Elevator is not too bad now but I'm hopeful there's enough throw in ailerons to make her turn.
The horns are mounted inward near the fuse and have to move an aileron that runs the full wingspan. That bending moment is a little strange.
Hey, for USD $45.00 ? My expectations were set in the right place. Just getting started. Will give a second attempt on Friday, weather permitting.
P.S. Did you hear about the BP/Conoco find in the Gulf of Mexico? 4900ft deep? Wow !