BeechTalk - BT - Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Diesel

Username Protected · **Posted:** 21 Oct 2020, 19:30

Username Protected wrote:

[Sept 4th]
He did do some static thrust measurements. He rigged it to the rear tire and measured force there and the force applied on the tires and then calculated to just over 800 lbs.

800 seems low for a 300+hp engine, and 175hp seems low for that engine- at least for the output he's trying to achieve out of it and the demonstrated takeoff performance on his televised takeoff runs.

Still, the numbers don't add up no matter which way you look at them.

We've already agreed in this thread that the engine installation badly needs a really good, experienced, resourceful, diesel engine tuner.

I think it could benefit from a good propeller guy too.

:scratch:

Just for comparison, some of the VAF guys get up to 800lbf static out of an O-360 with some reasonable prep and a good propeller. Different airplane, different engine and propeller, different cruise point, but it's a number. (The O-360 in a C172 gets more like 500-600.) It's not really an apples-to-apples comparison though, or apples-to-oranges, or apples-to-pomelos, or...

Username Protected · **Posted:** 21 Oct 2020, 19:52

Username Protected wrote:

Onlooker: Say, Pete, have you dynoed that engine?

Peter: No, but I compared it to a video of a 200hp SR20 that weighed 1000# less, at an airport 1000’ higher, with no knowledge of OAT, and got speeds that were within measurement error of that, so I figure I’m at about 300hp.

Never look for factual data when uneducated wild guesses are available.

Quote:

He did cover the wheel wells, but even there he added weight when he didn’t have to. Why use 200mph tape when you can use sheets of aluminum?

Seems to me that given Peter's affection for bailing wire+bubblegum fixes, I'm just surprised he didn't use duct tape.

Username Protected · **Posted:** 21 Oct 2020, 19:56

I am a fairly early deposit holder and I've been skeptical for some time, and still am, that I will ever own or fly a raptor.

But I received Peter's letter today, basically telling me to take my deposit back and he'd hold my place in line for me.

I know he's made plenty of mistakes and documented them. He's certainly not taken any of my advice about separating power plant and airframe and attacking separately. But he's been nothing but honest and beyond fair in his financial dealings with his deposit holders.

Several of you have made some pretty derogatory comments about his integrity and him attempting to make off with the deposits.

Now what do you have to say?

Username Protected · **Posted:** 21 Oct 2020, 20:01

Username Protected wrote:

Perhaps we should start a pool regarding the week he will have the 40TT completed?

Does that count include high speed taxi, and ground effect hops?

Username Protected · **Posted:** 21 Oct 2020, 21:13

Username Protected wrote:

Several of you have made some pretty derogatory comments about his integrity and him attempting to make off with the deposits.

Now what do you have to say?

It looks like I might be wrong and I hope I’m wrong.

I also hope this contraption doesn’t kill anyone.

I like being wrong when it comes to speculation of bad outcomes.

Username Protected · **Posted:** 21 Oct 2020, 21:18

Username Protected wrote:

Does that count include high speed taxi, and ground effect hops?

The 40 hours of Phase 1 testing is where one must establish the numbers for the Operating Limitations.
Best rate of climb
Best angle of climb
Best glide
Stall clean
Stall dirty
Yada
Yada

EAA now has test cards for homebuilders to walk through Phase 1 step-by-step.

Username Protected · **Posted:** 22 Oct 2020, 07:29

Username Protected wrote:

Several of you have made some pretty derogatory comments about his integrity and him attempting to make off with the deposits.

Now what do you have to say?

It appears that my comparisons of Jim Bede were wrong. But I stand by my comparison of Peter with “Zoom” Campbell and others with personality disorders.

Username Protected · **Posted:** 22 Oct 2020, 15:42

Username Protected wrote:

According to a post on HBA, a long while back the engine did get dynoed. The dyno said it made 175hp @3900 rpm. Peter’s explanation......the dyno is broken.

Any idea if the 175HP is with or without the belt drive?

Username Protected · **Posted:** 22 Oct 2020, 19:08

I’d say without.

Username Protected · **Posted:** 22 Oct 2020, 20:36

Username Protected wrote:

I’d say without.

That's from this 2017 video, but it just shows the setup, not any dyno results.

[youtube]https://youtu.be/lKsJZXBdNos[/youtube]

Username Protected · **Posted:** 22 Oct 2020, 20:54

Here's another 2017 video, where he concludes the dyno is broken, reading only about 160hp instead of 2x that. Peter mentions he'll try to find another dyno in the future.

Skip to 6:30 unless you want to hear all about the air-conditioner design.

[youtube]https://youtu.be/4wLB_mPSdfg[/youtube]

Username Protected · **Posted:** 22 Oct 2020, 21:07

And here, at the very end, you see how Peter concludes the power is 351 hp. This is based on a spreadsheet accounting for fuel flow and manifold pressure (not a force measurement).

[youtube]https://youtu.be/ZUygvsN0v6M[/youtube]

Username Protected · **Posted:** 22 Oct 2020, 21:23

I'm kinda surprised he hasn't rigged a poor man's dyno by placing a scale under each wheel, doing a high power turn, and deriving propeller torque from the difference between the left and right wheels. (Torque × rpm = horsepower). Point those wingtip cameras at the scale readouts and get real time data... it'd be fun to watch, even if it's not a very good idea.
:duck: