Helio Cruise Speeds

[JamesCaird]

Hi All-  Could you guys chime in on the kind of Cruise speeds you find normal for your Helios? If you could, qualify your experience where pertinent with regard to what configuration you Helio is in:  Tail wheel?  Tri-gear of floats?

I found with a Helio 800 on tri-gear average loading 110kts in cruise but that includes a nosewheel/trigear.
On floats/amphibs I knocked off 10 kts for 100kts cruise.    I could go faster but you start pushng pretty steeply up the fuel burn curve.

Many thanks for responses. /  Cheers/  JC

[heliodriver]

My 391-B on 29 inch tires was in the range of 118 to 123 MPH at 2600 / 24.  The 395 I have now on 31 inch tires is about 135MPH at the same setting.  The 395 remarkably still goes 105 to 110 at the minimum reasonable setting of 2200 / 20.  It can cruise at 105 to 110MPH burning about 12.8 to 13 GPH.  I don't run down there that often but for a long range, fuel conservation mode it would serve me well.  It's also quiet and relaxing there.  A nice headspace.  If I want to fly the 395 at 135 MPH I'm pouring on the petrol at 17 GPH.

[dtreid]

My 391b at 2600 rpm/20" is 113mph

[paullapoint]

My 391b less than 3000 msl:
             115mph 2600/22 burning 11.6
             120mph 2600/24 burning 12.8
             125mph 2600/26 burning 14.8-was doing this on a recent trip to break in cylinders, don't usually run it this hard
                                                                                            Paul
                                                   

[farmerflyer]

Back in March 2015 I did a real test using gps ground speed averages, and I’ll paste what I posted then:  Bob...I was working from a poor memory. I was flying this morning and did a real check. The conditions are the same as my previous post with the addition of a 40F temp and a weight of 3/4 fuel plus pilot.
2600rpm @ 20" gets 118mph,
2600rpm @ 22" gets 125,
2750rpm @ 22" gets 133,
3200rpm @ 24" gets 139.
This is a little better!
Regards,
Richard Reid
This is a H395A with the GO435 at 5000’ asl, lightly loaded. Back then my ailerons were in perfect trail. I since rigged them 3/4” down and lost an honest 5mph but gained considerable lateral stability. Fuel burn at 20/2600 is 11.5 usgph.  Richard

[Louis]

d with a Helio 800 on tri-gear average loading 110kts in cruise but that includes a nosewheel/trigear.
On floats/amphibs I knocked off 10 kts for 100kts cruise.   

My 800 was tailwheel.  Around 114.  104 on amphibious.  So may ge this 4 k more than you was just an instrument error.  That was at 3000 ft, 20.5 gph.  And sometimes 21 gph. 

Installed Gami, tried LOP.  Didn,t get a lot of sucess because lacking the power on amphibious. 

Once i was able to do a long leg in the Caribeans at 18.5 on wheels, at 10000 feet.  LOP.  But i was nervous because i choose a straight leg of 5 hours over the water and the wind picked up in the face.  So i was playing a lot to lower the GPH, and calculating speed, range etc

The 800 that was modified with a cowling without landing lights by the gentleman who was making the aluminium legs was supposed to fly 15 k more.  Better cooling, better cowling, LOP feasible.    He did some work also on the 700 to have better cooling and speed. 

My 295 is STC with fuel injection.  I get about the same speed than the 800.  Maybe 5 k less for each configuration.  But the GPH is more around 12.5.   Tried it with Gami and LOP,  still no real success.  Not at the speed i want to keep.. 

Louis

[Louis]

Once at JAARS, i saw a Helio that was worked to have less drag.  A lot of work everywhere.  They even removed the eyebrow over the windshield.  If i remember well, the people at Jarrs were not convinced of the work involved vs the new speed

Louis

[andrewstolte]

I consistently fly a 400 mile trip at 6500 to 8500 feet and get 128KTS (147 mph) TAS, with a power setting of24/2600.  295 with 800x6 tires.

[JamesCaird]

Thank you, guys.  These numbers are mostly consistant with my own experience.  It seems early cruise speed expectations from Helio were a bit exagerated?
    For me with a nose wheel H800 I would at some speeds get a slow occillation/yaw which I thought was likely the nose wheel drag up front. 
    On that note I think I saw a photo of one of Louis's Helios with a ventral fin while on the amphibs. Cheers/  JC

[Louis]

    On that note I think I saw a photo of one of Louis's Helios with a ventral fin while on the amphibs. Cheers/  JC

Both my 800 and the 295 do have a ventral fin when on amphibs.  Not really to prevent that oscillation you experience, but for crosswind landings on a runway.  The 800 by the STC of the 4000 PK, and the 295 on wipline by test for the one time approval.  Without the ventral fin, landing with a crosswind on a runway was too diffulcult.  Once i had the nose up, there was more side surface in front of the CG than in the back.  So at a certain point, the nose of the aircraft was turning not toward the wind, but away from it.  Very strange to handle.  So i had to land fast and flat, without flaps, or put a ventral fin and land slow, with flaps, and easy. 

Water landing was not a problem since we manage almost every time to have the wind on the nose.

On floats, as you put the nose more up, more side surface of the floats moves in front of the CG.  Since the floats are already more thick in the front than in the back.  It is very rare to see a less than 50 years floats certification without a ventral fin.  There is sometimes small winglet on the stab, like it was approoved on Beavers, to remove the underfuselage fin.   That approval was good to remove oscillation at cruze speed, but didn't help at approach speed.  Beaver such equipped on floats spin to death at a rate of one per year.  One per year.  Thousands hours pilots.

The ones with underfuselage fin never spin to death.  Wipline, who know a lot about float flying, does ask for an underwing fin on the amphibious Beaver.

With a Helio, i am sure the interceptor would do the job of preventing a spin.

Louis


We can see in the video how the spins start:

https://www.youtube.com/watch?v=11ZzeZFnbn4

In this one, you can see how the wind from the right, was pushing the nose to the left.  Too much side surface in front of the CG at that angle:

https://www.youtube.com/watch?v=HqVvFMRnpIU

Crash report say it all:  a right wind gust who veered the nose to the left.  There is no way that can happen if you have sufficient side surface behind the CG.  Without a fin, on floats with a big angle, you end up with more side surface in front of the CG. 

The report:  https://www.baaa-acro.com/crash/crash-de-havilland-dhc-2-beaver-anchorage-0

This one is a hoax i think.  It was ordered to make this film.  But nevertheless it did not had any underfuselage fin.  Or winglet.  I don't thing it would had change something in this case:

https://www.youtube.com/watch?v=EzPSjBPAlMQ


When in a spin, it is the wind under the fuselage that will exit the spin.  So it does take an underfuselage fin for aircraft that does not have a part of their rudder under the stab.  Like the Beaver.  When they made the Oter, they did put a lot of the rudder surface below the stab.  Never heard of an Oter to spin to death.

Difference between the rudder of the Otter and the Beaver:

[Jason Stephens]

That first one at Lake Hood was one of our former instructors/towpilots.  Nice guy, good pilot.  At talked to him at length after the accident.  I'm glad he and his passengers survived.  Gusty day and it lifted off earlier than he expected and he was clearly too slow climbing through the turbulence coming over the buildings.  Maybe a lower fin would've helped but it was technique that got him I think more than anything.

[yukonranger]

d with a Helio 800 on tri-gear average loading 110kts in cruise but that includes a nosewheel/trigear.
On floats/amphibs I knocked off 10 kts for 100kts cruise.   

My 800 was tailwheel.  Around 114.  104 on amphibious.  So may ge this 4 k more than you was just an instrument error.  That was at 3000 ft, 20.5 gph.  And sometimes 21 gph. 

Installed Gami, tried LOP.  Didn,t get a lot of sucess because lacking the power on amphibious. 

Once i was able to do a long leg in the Caribeans at 18.5 on wheels, at 10000 feet.  LOP.  But i was nervous because i choose a straight leg of 5 hours over the water and the wind picked up in the face.  So i was playing a lot to lower the GPH, and calculating speed, range etc

The 800 that was modified with a cowling without landing lights by the gentleman who was making the aluminium legs was supposed to fly 15 k more.  Better cooling, better cowling, LOP feasible.    He did some work also on the 700 to have better cooling and speed. 

My 295 is STC with fuel injection.  I get about the same speed than the 800.  Maybe 5 k less for each configuration.  But the GPH is more around 12.5.   Tried it with Gami and LOP,  still no real success.  Not at the speed i want to keep.. 

Louis

Louis, do you notice any increased performance with the FI STC?  I assume it has a larger throttle plate and hence more MP.  The cylinder to cylinder mixture distribution should be better also but is a performance improvemt actually noticeable?

Thanks

Mike

[JamesCaird]

Thanks, guys, again.  This is alot of useful info.

And, Louis, thanks for the ventral fin background.  A little thread drift but we certainly enjoy the input from so much accumulated experience with these Helios.

On the last video clip of the Beaver flipping in the lake-  That was for a film called "The Mother Lode" a generally  poor movie but it had some good Beaver Flying in the first half around BC, I think.  I have played that clip many times before trying to  figure out how they did that crash, model? remote control?  I have been in the movie business some myself and when you see that crash landing shot and then the closeups of the Beaver floating upside down I want to know how they did that!  Anyway- looks like they crashed a real Beaver but not a spin in. That clip must be a "must see" in the Beaver world.

Many thanks/  JC

[Kevin Dunn]

Louis,

Just to comment on the JAARS Helio with the speed mods. I was there in December and they have removed the mod and gone back to the factory configuration on that 295. Didn't help that much, and I talked to one of their guys a few years ago who said he thought it caused some weird airflow issues with the vertical. Regardless, not enough speed gain to justify the expense/weight of the mod.

Kevin

[JamesCaird]

Kevin-  Which JAARS speed mod are you describing?  The eyebrow (center wing leading edge on fuselage)? / JC